Testing Ultracool Atmospheres with Mass Benchmarks

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.; Liu, Michael C.

2011-08-01

After years of patient orbital monitoring, there is now a sample of ~10 very low-mass stars and brown dwarfs with precise (~5%) dynamical masses. These binaries represent the gold standard for testing substellar theoretical models. Work to date has identified problems with the model-predicted broad-band colors, effective temperatures, and possibly even luminosity evolution with age. However, our ability to test models is currently limited by how well the individual components of these highly prized binaries are characterized. To solve this problem, we propose to obtain narrow-band imaging with Keck/OSIRIS LGS to measure resolved SEDs for this first sizable sample of ultracool binaries with well-determined dynamical masses. This multi- band photometry will enable us to precisely estimate spectral types and effective temperatures of individual binary components, providing the strongest constraints to date on widely used evolutionary and atmospheric models. Our proposed Keck observations are much less daunting in comparison to the years of orbital monitoring needed to yield dynamical masses, but these data are equally vital for robust tests of theory. (Note: Our proposed time is intended to replace the 1 night awarded by NOAO to carry out this program in 2010B, which was completely lost due to weather.)

Hot subdwarfs in (eclipsing) binaries with brown dwarf or low-mass main-sequence companions

NASA Astrophysics Data System (ADS)

Schaffenroth, Veronika; Geier, Stephan; Heber, Uli

2014-09-01

The formation of hot subdwarf stars (sdBs), which are core helium-burning stars located on the extended horizontal branch, is not yet understood. Many of the known hot subdwarf stars reside in close binary systems with short orbital periods of between a few hours and a few days, with either M-star or white-dwarf companions. Common-envelope ejection is the most probable formation channel. Among these, eclipsing systems are of special importance because it is possible to constrain the parameters of both components tightly by combining spectroscopic and light-curve analyses. They are called HW Virginis systems. Soker (1998) proposed that planetary or brown-dwarf companions could cause the mass loss necessary to form an sdB. Substellar objects with masses greater than >10 M_J were predicted to survive the common-envelope phase and end up in a close orbit around the stellar remnant, while planets with lower masses would entirely evaporate. This raises the question if planets can affect stellar evolution. Here we report on newly discovered eclipsing or not eclipsing hot subdwarf binaries with brown-dwarf or low-mass main-sequence companions and their spectral and photometric analysis to determine the fundamental parameters of both components.

The Scorched Atmosphere of a Low Mass Star

NASA Astrophysics Data System (ADS)

Hines, Dean; Schmidt, Gary

2006-05-01

The recent detection of mid-IR emission from the brown dwarf companion to the white dwarf GD1400 (Farihi & Christopher 2005) demonstrates the power of IRAC for characterizing low-mass companions to white dwarf (WD) stars. Compared with GD1400, the close binary system SDSS121209.31+013627.7 (hereafter SDSS1212) is potentially a far more significant target in this effort. SDSS1212 consists of a magnetic WD plus a low-mass companion in a very close (tidally-locked) orbit (a ~ 0.6 Rsun, P ~ 90 mins). The companion shows the effects of irradiation of its atmosphere by the WD, and the tidal lock (and inclination) ensures that we view the illuminated and far-side hemispheres during each orbit. Ground-based, J-band upper limits constrain the companion to be a late-type brown dwarf (L5 or later). Thus, SDSS1212 is an ideal system for studying the atmosphere of a sub-stellar object heated by a strong continuum. Indeed, the total irradiating flux at ~1 Rsun from a T ~ 10,000K WD is comparable to that at r ~ 0.1 AU from a sun-like main sequence star, and SDSS1212 is the only WD + brown dwarf binary whose orbital period is known. Given its importance for the characterization of planetary atmosphere and binary star evolution, we propose to carry out phase-resolved 3.6?8 micron imaging of the SDSS1212 system with the dual goals of: 1) characterizing the orbit-averaged photometric properties of the low-mass companion, and thus discerning its placement within the ever-expanding zoo of substellar objects; and 2) measuring what is expected to be a modulation of up to 0.4 mag in the net mid-IR brightness of the binary, thereby providing an empirical point of comparison for current theoretical efforts to predict the response of "hot Jupiters" to irradiation by their parent stars. Coupled with the exquisite photometric stability of IRAC and the benign environment of Spitzer, this unique target offers an exceptional opportunity to study the effects of irradiation from host stars on their substellar companions.

An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 M⊙ giant star HIP 67537

NASA Astrophysics Data System (ADS)

Jones, M. I.; Brahm, R.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Melo, C. H. F.; Vos, J.; Rojo, P.

2017-06-01

We report the discovery of a substellar companion around the giant star HIP 67537. Based on precision radial velocity measurements from CHIRON and FEROS high-resolution spectroscopic data, we derived the following orbital elements for HIP 67537 b: mb sin I = 11.1+0.4-1.1Mjup, a =4.9+0.14-0.13 AU and e = 0.59+0.05-0.02 . Considering random inclination angles, this object has ≳65% probability to be above the theoretical deuterium-burning limit, thus it is one of the few known objects in the planet to brown-dwarf (BD) transition region. In addition, we analyzed the Hipparcos astrometric data of this star, from which we derived a minimum inclination angle for the companion of 2 deg. This value corresponds to an upper mass limit of 0.3 M⊙, therefore the probability that HIP 67537 b is stellar in nature is ≲7%. The large mass of the host star and the high orbital eccentricity makes HIP 67537 b a very interesting and rare substellar object. This is the second candidate companion in the brown dwarf desert detected in the sample of intermediate-mass stars targeted by the EXoPlanets aRound Evolved StarS (EXPRESS) radial velocity program, which corresponds to a detection fraction of f = +2.0-0.5 %. This value is larger than the fraction observed in solar-type stars, providing new observational evidence of an enhanced formation efficiency of massive substellar companions in massive disks. Finally, we speculate about different formation channels for this object. Based on observations collected at La Silla - Paranal Observatory under programs ID's 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345 and through the Chilean Telescope Time under programs ID's CN-12A-073, CN-12B-047, CN-13A-111, CN-2013B-51, CN-2014A-52, CN-15A-48, CN-15B-25 and CN-16A-13.

ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simón-Díaz, S.; Caballero, J. A.; Apellániz, J. Maíz

2015-02-01

We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus other available information onmore » photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the σ Ori Aa, Ab pair. We provided indirect arguments indicating that σ Ori B is a fast-rotating early B dwarf. The FASTWIND+BONNSAI analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while σ Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the σ Orionis cluster, at 3 ± 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the σ Orionis cluster, the interpretation of the strong X-ray emission detected for σ Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects.« less

A SUBSTELLAR COMPANION TO THE WHITE DWARF-RED DWARF ECLIPSING BINARY NN Ser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, S.-B.; Dai, Z.-B.; Liao, W.-P.

2009-11-20

NN Ser is a short-period (P = 3.12 hr) close binary containing a very hot white dwarf primary with a mass of 0.535 M{sub sun} and a fully convective secondary with a mass of 0.111 M{sub sun}. The changes in the orbital period of the eclipsing binary were analyzed based on our five newly determined eclipse times together with those compiled from the literature. A small-amplitude (0fd00031) cyclic period variation with a period of 7.56 years was discovered to be superimposed on a possible long-term decrease. The periodic change was plausibly explained as the light-travel time effect via the presencemore » of a tertiary companion. The mass of the tertiary companion is determined to be M{sub 3}sin i' = 0.0107(+-0.0017) M{sub sun} when a total mass of 0.646 M{sub sun} for NN Ser is adopted. For orbital inclinations i' >= 49.{sup 0}56, the mass of the tertiary component was calculated to be M {sub 3} <= 0.014 M{sub sun}; thus it would be an extrasolar planet. The third body is orbiting the white dwarf-red dwarf eclipsing binary at a distance shorter than 3.29 AU. Since the observed decrease rate of the orbital period is about two orders larger than that caused by gravitational radiation, it can be plausibly interpreted by magnetic braking of the fully convective component, which is driving this binary to evolve into a normal cataclysmic variable.« less

A SUBSTELLAR COMMON PROPER-MOTION COMPANION TO THE PLEIAD H II 1348

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geissler, Kerstin; Metchev, Stanimir A.; Pham, Alfonse

2012-02-10

We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1.''1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptivemore » optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 {+-} 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.« less

The occurrence of planets and other substellar bodies around white dwarfs using K2

NASA Astrophysics Data System (ADS)

van Sluijs, L.; Van Eylen, V.

2018-03-01

The majority of stars both host planetary systems and evolve into a white dwarf (WD). To understand their post-main-sequence planetary system evolution, we present a search for transiting/eclipsing planets and other substellar bodies (SBs) around WDs using a sample of 1148 WDs observed by K2. Using transit injections, we estimate the completeness of our search. We place constraints on the occurrence of planets and SBs around WDs as a function of planet radius and orbital period. For short-period (P < 40 d) small objects, from asteroid-sized to 1.5 R⊕, these are the strongest constraints known to date. We further constrain the occurrence of hot Jupiters ( < 1.5 per cent), habitable zone Earth-sized planets ( < 28 per cent), and disintegrating short-period planets ( ˜ 12 per cent). We blindly recovered all previously known eclipsing objects, providing confidence in our analysis, and make all light curves publicly available.

ALMA Measurements of Circumstellar Material in the GQ Lup System

NASA Astrophysics Data System (ADS)

Wilner, David J.; MacGregor, Meredith A.; Czekala, Ian; Andrews, Sean M.; Dai, Yu Sophia; Herczeg, Gregory; Kratter, Kaitlin M.; Kraus, Adam L.; Ricci, Luca; Testi, Leonardo

2017-01-01

We present ALMA observations of the GQ Lup system, a young Sun-like star with a substellar mass companion in a wide-separation orbit. These observations of 870 micron continuum and CO J=3-2 line emission with beam 0.3 arcsec (45 AU) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The 3 sigma upper limit on the 870 micron flux density of < 0.15 mJy implies an upper limit on the GQ Lup b disk mass of about 0.04 solar masses for standard assumptions about optically thin dust emission. Given the non-detection of a circumplanetary disk around GQ Lup b, and other similar systems observed by ALMA, we discuss implications for formation mechanisms of wide-separation substellar companions.

The Thermal Phase Curve Offset on Tidally and Nontidally Locked Exoplanets: A Shallow Water Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penn, James; Vallis, Geoffrey K, E-mail: jp492@exeter.ac.uk, E-mail: g.vallis@exeter.ac.uk

2017-06-20

Using a shallow water model with time-dependent forcing, we show that the peak of an exoplanet thermal phase curve is, in general, offset from the secondary eclipse when the planet is rotating. That is, the planetary hot spot is offset from the point of maximal heating (the substellar point) and may lead or lag the forcing; the extent and sign of the offset are functions of both the rotation rate and orbital period of the planet. We also find that the system reaches a steady state in the reference frame of the moving forcing. The model is an extension ofmore » the well-studied Matsuno–Gill model into a full spherical geometry and with a planetary-scale translating forcing representing the insolation received on an exoplanet from a host star. The speed of the gravity waves in the model is shown to be a key metric in evaluating the phase curve offset. If the velocity of the substellar point (relative to the planet’s surface) exceeds that of the gravity waves, then the hot spot will lag the substellar point, as might be expected by consideration of forced gravity wave dynamics. However, when the substellar point is moving slower than the internal wave speed of the system, the hottest point may lead the passage of the forcing. We provide an interpretation of this result by consideration of the Rossby and Kelvin wave dynamics, as well as, in the very slowly rotating case, a one-dimensional model that yields an analytic solution. Finally, we consider the inverse problem of constraining planetary rotation rate from an observed phase curve.« less

A direct imaging search for close stellar and sub-stellar companions to young nearby stars

NASA Astrophysics Data System (ADS)

Vogt, N.; Mugrauer, M.; Neuhäuser, R.; Schmidt, T. O. B.; Contreras-Quijada, A.; Schmidt, J. G.

2015-01-01

A total of 28 young nearby stars (ages {≤ 60} Myr) have been observed in the K_s-band with the adaptive optics imager Naos-Conica of the Very Large Telescope at the Paranal Observatory in Chile. Among the targets are ten visual binaries and one triple system at distances between 10 and 130 pc, all previously known. During a first observing epoch a total of 20 faint stellar or sub-stellar companion-candidates were detected around seven of the targets. These fields, as well as most of the stellar binaries, were re-observed with the same instrument during a second epoch, about one year later. We present the astrometric observations of all binaries. Their analysis revealed that all stellar binaries are co-moving. In two cases (HD 119022 AB and FG Aqr B/C) indications for significant orbital motions were found. However, all sub-stellar companion candidates turned out to be non-moving background objects except PZ Tel which is part of this project but whose results were published elsewhere. Detection limits were determined for all targets, and limiting masses were derived adopting three different age values; they turn out to be less than 10 Jupiter masses in most cases, well below the brown dwarf mass range. The fraction of stellar multiplicity and of the sub-stellar companion occurrence in the star forming regions in Chamaeleon are compared to the statistics of our search, and possible reasons for the observed differences are discussed. Based on observations made with ESO telescopes at Paranal Observatory under programme IDs 083.C-0150(B), 084.C-0364(A), 084.C-0364(B), 084.C-0364(C), 086.C-0600(A) and 086.C-0600(B).

News From The Erebos Project

NASA Astrophysics Data System (ADS)

Schaffenroth, Veronika; Barlow, Brad; Geier, Stephan; Vučković, Maja; Kilkenny, Dave; Schaffenroth, Johannes

2017-12-01

Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs have been discovered orbiting hot subdwarf stars at very short orbital periods of 0.065 - 0.096 d. More than 8% of the close hot subdwarf binaries might have sub-stellar companions. This shows that such companions can significantly affect late stellar evolution and that sdB binaries are ideal objects to study this influence. Thirty-eight new eclipsing sdB binary systems with cool low-mass companions and periods from 0.05 to 0.5 d were discovered based on their light curves by the OGLE project. In the recently published catalog of eclipsing binaries in the Galactic bulge, we discovered 75 more systems. We want to use this unique and homogeneously selected sample to derive the mass distribution of the companions, constrain the fraction of sub-stellar companions and determine the minimum mass needed to strip off the red-giant envelope. We are especially interested in testing models that predict hot Jupiter planets as possible companions. Therefore, we started the EREBOS (Eclipsing Reflection Effect Binaries from the OGLE Survey) project, which aims at analyzing those new HW Vir systems based on a spectroscopic and photometric follow up. For this we were granted an ESO Large Program for ESO-VLT/FORS2. Here we give an update on the the current status of the project and present some preliminary results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geier, S.; Schaffenroth, V.; Drechsel, H.

Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The enormous mass loss required to remove the hydrogen envelope of the red-giant progenitor almost entirely can be explained by common envelope ejection. A rare subclass of these binaries are the eclipsing HW Vir binaries where the sdB is orbited by a dwarf M star. Here, we report the discovery of an HW Vir system in the course ofmore » the MUCHFUSS project. A most likely substellar object ({approx_equal}0.068 M{sub sun}) was found to orbit the hot subdwarf J08205+0008 with a period of 0.096 days. Since the eclipses are total, the system parameters are very well constrained. J08205+0008 has the lowest unambiguously measured companion mass yet found in a subdwarf B binary. This implies that the most likely substellar companion has not only survived the engulfment by the red-giant envelope, but also triggered its ejection and enabled the sdB star to form. The system provides evidence that brown dwarfs may indeed be able to significantly affect late stellar evolution.« less

Mapping the Shores of the Brown Dwarf Desert. III. Young Moving Groups

NASA Astrophysics Data System (ADS)

Evans, T. M.; Ireland, M. J.; Kraus, A. L.; Martinache, F.; Stewart, P.; Tuthill, P. G.; Lacour, S.; Carpenter, J. M.; Hillenbrand, L. A.

2012-01-01

We present the results of an aperture-masking interferometry survey for substellar companions around 67 members of the young (~8-200 Myr) nearby (~5-86 pc) AB Doradus, β Pictoris, Hercules-Lyra, TW Hya, and Tucana-Horologium stellar associations. Observations were made at near-infrared wavelengths between 1.2 and 3.8 μm using the adaptive optics facilities of the Keck II, Very Large Telescope UT4, and Palomar Hale Telescopes. Typical contrast ratios of ~100-200 were achieved at angular separations between ~40 and 320 mas, with our survey being 100% complete for companions with masses below ~0.25 M ⊙ across this range. We report the discovery of a 0.52 ± 0.09 M ⊙ companion to HIP 14807, as well as the detections and orbits of previously known stellar companions to HD 16760, HD 113449, and HD 160934. We show that the companion to HD 16760 is in a face-on orbit, resulting in an upward revision of its mass from M 2sin i ~ 14 M J to M 2 = 0.28 ± 0.04 M ⊙. No substellar companions were detected around any of our sample members, despite our ability to detect companions with masses below 80 M J for 50 of our targets: of these, our sensitivity extended down to 40 M J around 30 targets, with a subset of 22 subject to the still more stringent limit of 20 M J. A statistical analysis of our non-detection of substellar companions allows us to place constraints on their frequency around ~0.2-1.5 M ⊙ stars. In particular, considering companion mass distributions that have been proposed in the literature, we obtain an upper limit estimate of ~9%-11% for the frequency of 20-80 M J companions between 3 and 30 AU at 95% confidence, assuming that their semimajor axes are distributed according to d {N}/da \\propto a^{-1} in this range.

McDonald Observatory Planetary Search - A high precision stellar radial velocity survey for other planetary systems

NASA Technical Reports Server (NTRS)

Cochran, William D.; Hatzes, Artie P.

1993-01-01

The McDonald Observatory Planetary Search program surveyed a sample of 33 nearby F, G, and K stars since September 1987 to search for substellar companion objects. Measurements of stellar radial velocity variations to a precision of better than 10 m/s were performed as routine observations to detect Jovian planets in orbit around solar type stars. Results confirm the detection of a companion object to HD114762.

THE EVOLUTION OF CIRCUMPLANETARY DISKS AROUND PLANETS IN WIDE ORBITS: IMPLICATIONS FOR FORMATION THEORY, OBSERVATIONS, AND MOON SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shabram, Megan; Boley, Aaron C.

2013-04-10

Using radiation hydrodynamics simulations, we explore the evolution of circumplanetary disks around wide-orbit proto-gas giants. At large distances from the star ({approx}100 AU), gravitational instability followed by disk fragmentation can form low-mass substellar companions (massive gas giants and/or brown dwarfs) that are likely to host large disks. We examine the initial evolution of these subdisks and their role in regulating the growth of their substellar companions, as well as explore consequences of their interactions with circumstellar material. We find that subdisks that form in the context of GIs evolve quickly from a very massive state. Long-term accretion rates from themore » subdisk onto the proto-gas giant reach {approx}0.3 Jupiter masses kyr{sup -1}. We also find consistency with previous simulations, demonstrating that subdisks are truncated at {approx}1/3 of the companion's Hill radius and are thick, with (h/r) of {approx}> 0.2. The thickness of subdisks draws to question the use of thin-disk approximations for understanding the behavior of subdisks, and the morphology of subdisks has implications for the formation and extent of satellite systems. These subdisks create heating events in otherwise cold regions of the circumstellar disk and serve as planet formation beacons that can be detected by instruments such as ALMA.« less

The `DODO' survey - I. Limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa2)

NASA Astrophysics Data System (ADS)

Burleigh, M. R.; Clarke, F. J.; Hogan, E.; Brinkworth, C. S.; Bergeron, P.; Dufour, P.; Dobbie, P. D.; Levan, A. J.; Hodgkin, S. T.; Hoard, D. W.; Wachter, S.

2008-05-01

We report limits in the planetary-mass regime for companions around the nearest single white dwarf to the Sun, van Maanen's star (vMa2), from deep J-band imaging with Gemini North and Spitzer Infrared Array Camera (IRAC) mid-IR photometry. We find no resolved common proper motion companions to vMa2 at separations from 3 to 45 arcsec, at a limiting magnitude of J ~ 23. Assuming a total age for the system of 4.1 +/- 1Gyr, and utilizing the latest evolutionary models for substellar objects, this limit is equivalent to companion masses >7 +/- 1MJup(Teff ~ 300K). Taking into account the likely orbital evolution of very low mass companions in the post-main-sequence phase, these J-band observations effectively survey orbits around the white dwarf progenitor from 3 to 50au. There is no flux excess detected in any of the complimentary Spitzer IRAC mid-IR filters. We fit a white dwarf model atmosphere to the optical BVRI, JHK and IRAC photometry. The best solution gives Teff = 6030 +/- 240K, logg = 8.10 +/- 0.04 and, hence, M = 0.633 +/- 0.022Msolar. We then place a 3σ upper limit of 10 +/- 2MJup on the mass of any unresolved companion in the 4.5μm band.

PLANETS AROUND LOW-MASS STARS (PALMS). V. AGE-DATING LOW-MASS COMPANIONS TO MEMBERS AND INTERLOPERS OF YOUNG MOVING GROUPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowler, Brendan P.; Montet, Benjamin T.; Riddle, Reed

2015-06-10

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7–M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8–120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (∼10–100 M{sub Jup}) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each systemmore » to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892–0929121 C (40–60 M{sub Jup}) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ∼40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229–2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the Pleiades.« less

MUCHFUSS: Status and Highlights

NASA Astrophysics Data System (ADS)

Geier, S.; Kupfer, T.; Barlow, B.; Schaffenroth, V.; Fürst, F.; Heuser, C.; Ziegerer, E.; Heber, U.; Marsh, T.; Maxted, P.; Östensen, R.; O'Toole, S.; Gänsicke, B.; Napiwotzki, R.

2014-04-01

The MUCHFUSS project aims at finding sdBs with massive compact companions. Here we report on the current status of our spectroscopic and photometric follow-up campaigns and present some highlight results. We derive orbital solutions of seven new sdB binaries and estimate the fraction of close substellar companions to sdBs. Finally, we present an ultracompact sdB+WD binary as possible progenitor of a thermonuclear supernova and connect it to the only known hypervelocity subdwarf star, which might be the donor remnant of such an event.

IRAS 16253–2429: THE FIRST PROTO-BROWN DWARF BINARY CANDIDATE IDENTIFIED THROUGH THE DYNAMICS OF JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsieh, Tien-Hao; Lai, Shih-Ping; Belloche, Arnaud

2016-07-20

The formation mechanism of brown dwarfs (BDs) is one of the long-standing problems in star formation because the typical Jeans mass in molecular clouds is too large to form these substellar objects. To answer this question, it is crucial to study a BD in the embedded phase. IRAS 16253–2429 is classified as a very low-luminosity object (VeLLO) with an internal luminosity of <0.1 L {sub ⊙}. VeLLOs are believed to be very low-mass protostars or even proto-BDs. We observed the jet/outflow driven by IRAS 16253–2429 in CO (2–1), (6–5), and (7–6) using the IRAM 30 m and Atacama Pathfinder Experimentmore » telescopes and the Submillimeter Array (SMA) in order to study its dynamical features and physical properties. Our SMA map reveals two protostellar jets, indicating the existence of a proto-binary system as implied by the precessing jet detected in H{sub 2} emission. We detect a wiggling pattern in the position–velocity diagrams along the jet axes, which is likely due to the binary orbital motion. Based on this information, we derive the current mass of the binary as ∼0.032 M{sub ⊙}. Given the low envelope mass, IRAS 16253–2429 will form a binary that probably consist of one or two BDs. Furthermore, we found that the outflow force as well as the mass accretion rate are very low based on the multi-transition CO observations, which suggests that the final masses of the binary components are at the stellar/substellar boundary. Since IRAS 16253 is located in an isolated environment, we suggest that BDs can form through fragmentation and collapse, similar to low-mass stars.« less

Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling

NASA Astrophysics Data System (ADS)

Nilsson, R.; Veicht, A.; Giorla Godfrey, P. A.; Rice, E. L.; Aguilar, J.; Pueyo, L.; Roberts, L. C., Jr.; Oppenheimer, R.; Brenner, D.; Luszcz-Cook, S. H.; Bacchus, E.; Beichman, C.; Burruss, R.; Cady, E.; Dekany, R.; Fergus, R.; Hillenbrand, L.; Hinkley, S.; King, D.; Lockhart, T.; Parry, I. R.; Sivaramakrishnan, A.; Soummer, R.; Vasisht, G.; Zhai, C.; Zimmerman, N. T.

2017-03-01

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲30 au, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion’s physical characteristics, we acquired the first low-resolution (R ˜ 50) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory’s 5 m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the Y, J, and H bands (˜952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with χ 2 minimization suggesting a best fit for spectral type T7.0 ± 1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature T eff = 741 ± 25 K and surface gravity {log}g=4.3+/- 0.5 dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date.

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

NASA Astrophysics Data System (ADS)

Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; de Wit, Julien; Burdanov, Artem; Van Grootel, Valérie; Burgasser, Adam J.; Triaud, Amaury H. M. J.; Opitom, Cyrielle; Demory, Brice-Olivier; Sahu, Devendra K.; Bardalez Gagliuffi, Daniella; Magain, Pierre; Queloz, Didier

2016-05-01

Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun. Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks, there should be a large but hitherto undetected population of terrestrial planets orbiting them—ranging from metal-rich Mercury-sized planets to more hospitable volatile-rich Earth-sized planets. Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star. Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system.

Temperate Earth-sized planets transiting a nearby ultracool dwarf star.

PubMed

Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M; Delrez, Laetitia; de Wit, Julien; Burdanov, Artem; Van Grootel, Valérie; Burgasser, Adam J; Triaud, Amaury H M J; Opitom, Cyrielle; Demory, Brice-Olivier; Sahu, Devendra K; Bardalez Gagliuffi, Daniella; Magain, Pierre; Queloz, Didier

2016-05-12

Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as 'ultracool dwarfs'. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun. Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks, there should be a large but hitherto undetected population of terrestrial planets orbiting them--ranging from metal-rich Mercury-sized planets to more hospitable volatile-rich Earth-sized planets. Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star. Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system.

MAPPING THE SHORES OF THE BROWN DWARF DESERT. III. YOUNG MOVING GROUPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, T. M.; Ireland, M. J.; Stewart, P.

2012-01-10

We present the results of an aperture-masking interferometry survey for substellar companions around 67 members of the young ({approx}8-200 Myr) nearby ({approx}5-86 pc) AB Doradus, {beta} Pictoris, Hercules-Lyra, TW Hya, and Tucana-Horologium stellar associations. Observations were made at near-infrared wavelengths between 1.2 and 3.8 {mu}m using the adaptive optics facilities of the Keck II, Very Large Telescope UT4, and Palomar Hale Telescopes. Typical contrast ratios of {approx}100-200 were achieved at angular separations between {approx}40 and 320 mas, with our survey being 100% complete for companions with masses below {approx}0.25 M{sub Sun} across this range. We report the discovery of amore » 0.52 {+-} 0.09 M{sub Sun} companion to HIP 14807, as well as the detections and orbits of previously known stellar companions to HD 16760, HD 113449, and HD 160934. We show that the companion to HD 16760 is in a face-on orbit, resulting in an upward revision of its mass from M{sub 2}sin i {approx} 14 M{sub J} to M{sub 2} = 0.28 {+-} 0.04 M{sub Sun }. No substellar companions were detected around any of our sample members, despite our ability to detect companions with masses below 80 M{sub J} for 50 of our targets: of these, our sensitivity extended down to 40 M{sub J} around 30 targets, with a subset of 22 subject to the still more stringent limit of 20 M{sub J}. A statistical analysis of our non-detection of substellar companions allows us to place constraints on their frequency around {approx}0.2-1.5 M{sub Sun} stars. In particular, considering companion mass distributions that have been proposed in the literature, we obtain an upper limit estimate of {approx}9%-11% for the frequency of 20-80 M{sub J} companions between 3 and 30 AU at 95% confidence, assuming that their semimajor axes are distributed according to dN/da{proportional_to}a{sup -1} in this range.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burgasser, Adam J.; Luk, Christopher; Bardalez Gagliuffi, Daniella

We report the identification of the M9 dwarf SDSS J000649.16-085246.3 as a spectral binary and radial velocity (RV) variable with components straddling the hydrogen-burning mass limit. Low-resolution near-infrared spectroscopy reveals spectral features indicative of a T dwarf companion, and spectral template fitting yields component types of M8.5 {+-} 0.5 and T5 {+-} 1. High-resolution near-infrared spectroscopy with Keck/NIRSPEC reveals pronounced RV variations with a semi-amplitude of 8.2 {+-} 0.4 km s{sup -1}. From these we determine an orbital period of 147.6 {+-} 1.5 days and eccentricity of 0.10 {+-} 0.07, making SDSS J0006-0852AB the third tightest very low mass binarymore » known. This system is also found to have a common proper motion companion, the inactive M7 dwarf LP 704-48, at a projected separation of 820 {+-} 120 AU. The lack of H{alpha} emission in both M dwarf components indicates that this system is relatively old, as confirmed by evolutionary model analysis of the tight binary. LP 704-48/SDSS J0006-0852AB is the lowest-mass confirmed triple identified to date, and one of only seven candidate and confirmed triples with total masses below 0.3 M{sub Sun} currently known. We show that current star and brown dwarf formation models cannot produce triple systems like LP 704-48/SDSS J0006-0852AB, and we rule out Kozai-Lidov perturbations and tidal circularization as a viable mechanism to shrink the inner orbit. The similarities between this system and the recently uncovered low-mass eclipsing triples NLTT 41135AB/41136 and LHS 6343ABC suggest that substellar tertiaries may be common in wide M dwarf pairs.« less

Moderate Resolution Spectroscopy of Substellar Companion Kappa Andromeda B

NASA Astrophysics Data System (ADS)

Wilcomb, Kielan; Konopacky, Quinn; Barman, Travis; Brown, Jessie; Brock, Laci; Macintosh, Bruce; Ruffio, Jean-Baptiste; Marois, Christian

2018-01-01

Recent direct imaging of exoplanets has revealed a population of Jupiter-like objects that orbit at large separations (~10-100 AU) from their host stars. These planets, with masses of ~2-14 MJup and temperatures of ~500-2000 K, remain a problem for the two main planet formation models—core accretion and gravitational instability. OSIRIS observations of directly imaged planets have expanded our understanding of their atmospheres, alluded to their formation, and uncovered individual molecular lines. Here, we present OSIRIS K band spectra of the “super-Jupiter,” Kappa Andromeda b. Kappa Andromeda b has a lower mass limit at the deuterium burning limit, but also has an uncertain age which may indicate the source is a higher mass brown dwarf. The spectra reveal resolved molecular lines from water and CO. We will present atmospheric properties of this object derived from comparison to PHOENIX atmosphere models, and measure a best fit C/O ratio for the source. We will compare our results to atmospheric properties of other brown dwarfs and gas giant planets in an effort to improve our knowledge of intricate atmospheres of young, substellar objects.

Limits on Line Bisector Variability for Stars with Extrasolar Planets

NASA Technical Reports Server (NTRS)

Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman, T.; Barden, S.; Deming, D.; Livingston, W. C.; Pilachowski, C.

2000-01-01

We present an analysis of high-resolution synoptic spectra of ten F- and G-type stars, seven of which exhibit periodic radial velocity variations due to the presence of one or more substellar companions. We searched for subtle periodic variations in photospheric line asymmetry, as characterized by line bisectors. In principle, periodic variations in line asymmetry observed at lower spectral resolution could mimic the radial velocity signature of a companion, but we find no significant evidence of such behavior in our data. Observations were obtained from 1998 March to 1999 February using the National Solar Observatory (NSO) 1.52-m McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction with the solar-stellar spectrograph, achieving a resolving power of 1.2x10(exp5). To characterize line asymmetry, we first measured line bisectors for the unblended Fe I photospheric line at 625.26 nm. To improve sensitivity to small fluctuations, we then combined points in each bisector to form a velocity displacement with respect to the line core. We searched for periodic variations in this displacement, finding no substantial difference between stars with substellar companions and those without reported companions. We find no correlation between bisector velocity displacement and the known orbital phase of substellar companions around our target stars. Simulations of a periodic signal with noise levels that mimic our measurement errors suggest that we can exclude bisector variations with amplitudes greater than about 20 m/s. These results support the conclusion that extrasolar planets best explain the observed periodic variations in radial velocity.

On Lithium-rich Red Giants. I. Engulfment of Substellar Companions

NASA Astrophysics Data System (ADS)

Aguilera-Gómez, Claudia; Chanamé, Julio; Pinsonneault, Marc H.; Carlberg, Joleen K.

2016-10-01

A small fraction of red giants are known to be lithium (Li) rich, in contradiction with expectations from stellar evolutionary theory. A possible explanation for these atypical giants is the engulfment of an Li-rich planet or brown dwarf by the star. In this work, we model the evolution of Li abundance in canonical red giants including the accretion of a substellar mass companion. We consider a wide range of stellar and companion masses, Li abundances, stellar metallicities, and planetary orbital periods. Based on our calculations, companions with masses lower than 15 {M}J dissolve in the convective envelope and can induce Li enrichment in regimes where extra mixing does not operate. Our models indicate that the accretion of a substellar companion can explain abundances up to A(Li) ≈ 2.2, setting an upper limit for Li-rich giants formed by this mechanism. Giants with higher abundances need another mechanism to be explained. For reasonable planetary distributions, we predict the Li abundance distribution of low-mass giants undergoing planet engulfment, finding that between 1% and 3% of them should have {{A}}({Li})≥slant 1.5. We show that depending on the stellar mass range, this traditional definition of Li-rich giants is misleading, as isolated massive stars would be considered anomalous while giants engulfing a companion would be set aside, flagged as normal. We explore the detectability of companion engulfment, finding that planets with masses higher than ∼ 7 {M}J produce a distinct signature, and that descendants of stars originating in the Li dip and low-luminosity red giants are ideal tests of this channel.

The Orbit of the L Dwarf + T Dwarf Spectral Binary SDSS J080531.84+481233.0

NASA Astrophysics Data System (ADS)

Burgasser, Adam J.; Blake, Cullen H.; Gelino, Christopher R.; Sahlmann, Johannes; Bardalez Gagliuffi, Daniella

2016-08-01

SDSS J080531.84+481233.0 is a closely separated, very-low-mass (VLM) binary identified through combined-light spectroscopy and confirmed as an astrometric variable. Here we report four years of radial velocity monitoring observations of the system that reveal significant and periodic variability, confirming the binary nature of the source. We infer an orbital period of 2.02 ± 0.03 years, a semimajor axis of 0.76{}-0.06+0.05 au, and an eccenticity of 0.46 ± 0.05, consistent with the amplitude of astrometric variability and prior attempts to resolve the system. Folding in constraints based on the spectral types of the components (L4 ± 0.7 and T5.5 ± 1.1), corresponding effective temperatures, and brown dwarf evolutionary models, we further constrain the orbital inclination of this system to be nearly edge-on (90° ± 19°), and deduce a large system mass ratio (M 2/M 1 = {0.86}-0.12+0.10), substellar components (M 1 = {0.057}-0.014+0.016 M ⊙, M 2 = {0.048}-0.010+0.008 M ⊙), and a relatively old system age (minimum age = {4.0}-1.2+1.9 Gyr). The measured projected rotational velocity of the primary ({V}{rot}\\sin I = 34.1 ± 0.7 km s-1) implies that this inactive source is a rapid rotator (period ≲ 3 hr) and a viable system for testing spin-orbit alignment in VLM multiples. Robust model-independent constraints on the component masses may be possible through measurement of the reflex motion of the secondary at wavelengths in which it contributes a greater proportion of the combined luminence, while the system may also be resolvable through sparse-aperature mask interferometry with adaptive optics. The combination of well-determined component atmospheric properties and masses near and/or below the hydrogen minimum mass make SDSS J0805+4812AB an important system for future tests of brown dwarf evolutionary models. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Low mass companions to nearby stars: Spectral classification and its relation to the stellar/substellar break

NASA Technical Reports Server (NTRS)

Kirkpatrick, J. Davy; Mccarthy, Donald W., Jr.

1994-01-01

The relationship between mass and spectral class for main-sequence stars has never been obtained for dwarfs cooler than M6; currently, the true nature of objects classified as M7, M8, M9, or later (be they stellar or substellar) is not known. In this paper, spectral types for the components in five low mass binary systems are estimated based on previously published infrared speckle measurements, red/infrared photometry, and parallax data, together with newly acquired high signal-to-noise composite spectra of the systems and revised magnitude difference relations for M dwarfs. For two of these binaries, the secondary has a smaller mass (less than 0.09 solar mass) than any object having a dynamically measured mass and a known spectral type, thus extending the spectral class/mass relation to lower masses than has previously been possible. Data from the higher mass components (0.09 solar mass less than M less than 0.40 solar mass) are consistent with earlier results; the two lowest mass objects -- though having mass errors which could place them on either side of the M dwarf/brown dwarf dividing line (Mass is about 0.08 solar mass) -- are found to have spectral types no cooler than M6.5 V. An extrapolation of the updated spectral class/mass relation to the hydrogen-burning limit suggests that objects of type M7 and later may be substellar. Direct confirmation of this awaits the discovery of a close, very late-type binary for which dynamical masses can be measured.

A SEMI-ANALYTICAL MODEL OF VISIBLE-WAVELENGTH PHASE CURVES OF EXOPLANETS AND APPLICATIONS TO KEPLER- 7 B AND KEPLER- 10 B

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Renyu; Demory, Brice-Olivier; Seager, Sara

2015-03-20

Kepler has detected numerous exoplanet transits by measuring stellar light in a single visible-wavelength band. In addition to detection, the precise photometry provides phase curves of exoplanets, which can be used to study the dynamic processes on these planets. However, the interpretation of these observations can be complicated by the fact that visible-wavelength phase curves can represent both thermal emission and scattering from the planets. Here we present a semi-analytical model framework that can be applied to study Kepler and future visible-wavelength phase curve observations of exoplanets. The model efficiently computes reflection and thermal emission components for both rocky andmore » gaseous planets, considering both homogeneous and inhomogeneous surfaces or atmospheres. We analyze the phase curves of the gaseous planet Kepler- 7 b and the rocky planet Kepler- 10 b using the model. In general, we find that a hot exoplanet’s visible-wavelength phase curve having a significant phase offset can usually be explained by two classes of solutions: one class requires a thermal hot spot shifted to one side of the substellar point, and the other class requires reflective clouds concentrated on the same side of the substellar point. Particularly for Kepler- 7 b, reflective clouds located on the west side of the substellar point can best explain its phase curve. The reflectivity of the clear part of the atmosphere should be less than 7% and that of the cloudy part should be greater than 80%, and the cloud boundary should be located at 11° ± 3° to the west of the substellar point. We suggest single-band photometry surveys could yield valuable information on exoplanet atmospheres and surfaces.« less

Photometric Properties for Selected Algol-type Binaries. VIII. The Triple Systems DI Peg and AF Gem Revisited

NASA Astrophysics Data System (ADS)

Yang, Yuan-Gui; Yang, Ying; Li, Shu-Zheng

2014-06-01

New extensive photometry for two triple binary stars, DI Peg and AF Gem, was performed from 2012 October to 2013 January, with two small telescopes at Xinglong station (XLs) of NAOC. From new multi-color observations and previously published ones in literature, the photometric models were (re)deduced using the updated Wilson-Devinney code. The results indicated that the low third lights exist in two classic Algol-type binaries, whose fill-out factors for the more massive components are fp = 78.2(± 0.4)% for DI Peg, and fp = 69.0(± 0.3)% for AF Gem, respectively. Through analyzing the O-C curves, the orbital periods for two binaries change in the complicated mode. The period of DI Peg possibly appears to show two light-time orbits, whose modulated periods are P 3 = 54.6(± 0.5) yr and P 4 = 23.0(± 0.6) yr, respectively. The inferred minimum masses for the inner and outer sub-stellar companions are M in = 0.095 M ⊙ and M out = 0.170 M ⊙, respectively. Therefore, DI Peg may be a quadruple star. The orbital period of AF Gem appears to show a continuous period decrease or a cyclic variation; the latter may be preferable. The cyclic oscillation, with a period of 120.3(± 2.5) yr, may be attributed to the light-time effect due to the third body. This kind of additional companion may extract angular momentum from the central system, which may play a key role in the evolution of the binary.

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits. IV. Gravitational instability rarely forms wide, giant planets

NASA Astrophysics Data System (ADS)

Vigan, A.; Bonavita, M.; Biller, B.; Forgan, D.; Rice, K.; Chauvin, G.; Desidera, S.; Meunier, J.-C.; Delorme, P.; Schlieder, J. E.; Bonnefoy, M.; Carson, J.; Covino, E.; Hagelberg, J.; Henning, T.; Janson, M.; Lagrange, A.-M.; Quanz, S. P.; Zurlo, A.; Beuzit, J.-L.; Boccaletti, A.; Buenzli, E.; Feldt, M.; Girard, J. H. V.; Gratton, R.; Kasper, M.; Le Coroller, H.; Mesa, D.; Messina, S.; Meyer, M.; Montagnier, G.; Mordasini, C.; Mouillet, D.; Moutou, C.; Reggiani, M.; Segransan, D.; Thalmann, C.

2017-06-01

Understanding the formation and evolution of giant planets (≥1 MJup) at wide orbital separation (≥5 AU) is one of the goals of direct imaging. Over the past 15 yr, many surveys have placed strong constraints on the occurrence rate of wide-orbit giants, mostly based on non-detections, but very few have tried to make a direct link with planet formation theories. In the present work, we combine the results of our previously published VLT/NaCo large program with the results of 12 past imaging surveys to constitute a statistical sample of 199 FGK stars within 100 pc, including three stars with sub-stellar companions. Using Monte Carlo simulations and assuming linear flat distributions for the mass and semi-major axis of planets, we estimate the sub-stellar companion frequency to be within 0.75-5.70% at the 68% confidence level (CL) within 20-300 AU and 0.5-75 MJup, which is compatible with previously published results. We also compare our results with the predictions of state-of-the-art population synthesis models based on the gravitational instability (GI) formation scenario with and without scattering. We estimate that in both the scattered and non-scattered populations, we would be able to detect more than 30% of companions in the 1-75 MJup range (95% CL). With the threesub-stellar detections in our sample, we estimate the fraction of stars that host a planetary system formed by GI to be within 1.0-8.6% (95% CL). We also conclude that even though GI is not common, it predicts a mass distribution of wide-orbit massive companions that is much closer to what is observed than what the core accretion scenario predicts. Finally, we associate the present paper with the release of the Direct Imaging Virtual Archive (DIVA), a public database that aims at gathering the results of past, present, and future direct imaging surveys. Based on observations collected at the European Southern Observatory, Chile (ESO Large Program 184.C-0157 and Open Time 089.C-0137A and 090.C-0252A).

Characterizing a New Candidate Benchmark Brown Dwarf Companion in the β Pic Moving Group

NASA Astrophysics Data System (ADS)

Phillips, Caprice; Bowler, Brendan; Liu, Michael C.; Mace, Gregory N.; Sokal, Kimberly R.

2018-01-01

Benchmark brown dwarfs are objects that have at least two measured fundamental quantities such as luminosity and age, and therefore can be used to test substellar atmospheric and evolutionary models. Nearby, young, loose associations such as the β Pic moving group represent some of the best regions in which to identify intermediate-age benchmark brown dwarfs due to their well-constrained ages and metallicities. We present a spectroscopic study of a new companion at the hydrogen-burning limit orbiting a low-mass star at a separation of 9″ (650 AU) in the 23 Myr old β Pic moving group. The medium-resolution near-infrared spectrum of this companion from IRTF/SpeX shows clear signs of low surface gravity and yields an index-based spectral type of M6±1 with a VL-G gravity on the Allers & Liu classification system. Currently, there are four known brown dwarf and giant planet companions in the β Pic moving group: HR 7329 B, PZ Tel B, β Pic b, and 51 Eri b. Depending on its exact age and accretion history, this new object may represent the third brown dwarf companion and fifth substellar companion in this association.

Planets Around Low-mass Stars (PALMS). V. Age-dating Low-mass Companions to Members and Interlopers of Young Moving Groups

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Shkolnik, Evgenya L.; Liu, Michael C.; Schlieder, Joshua E.; Mann, Andrew W.; Dupuy, Trent J.; Hinkley, Sasha; Crepp, Justin R.; Johnson, John Asher; Howard, Andrew W.; Flagg, Laura; Weinberger, Alycia J.; Aller, Kimberly M.; Allers, Katelyn N.; Best, William M. J.; Kotson, Michael C.; Montet, Benjamin T.; Herczeg, Gregory J.; Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Nielsen, Eric L.; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.

2015-06-01

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (˜10-100 MJup) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892-0929121 C (40-60 MJup) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ˜40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229-2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the Pleiades. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Program 090.A-9010(A)).

The Orbital Ephemeris of the Classical Nova RR Pictoris: Presence of a Third Body?

NASA Astrophysics Data System (ADS)

Vogt, N.; Schreiber, M. R.; Hambsch, F.-J.; Retamales, G.; Tappert, C.; Schmidtobreick, L.; Fuentes-Morales, I.

2017-01-01

The ex-nova RR Pic presents a periodic hump in its light curve which is considered to refer to its orbital period. By analyzing all available epochs of these hump maxima in the literature and then combining them with those from new light curves obtained in 2013 and 2014, we establish an unique cycle count scheme valid during the past 50 years and derive an ephemeris with the orbital period 0.145025959(15) days. The O—C diagram of this linear ephemeris reveals systematic deviations that could have different causes. One of them could be a light-travel-time effect caused by the presence of a hypothetical third body near the star/brown dwarf mass limit, with an orbital period of the order of 70 years. We also examine the difficulty of the problematic of detecting substellar or planetary companions of close red-dwarf white-dwarf binaries (including cataclysmic variables) and discuss other possible mechanisms responsible for the observed deviations in O—C. For RR Pic, we propose strategies to solve this question by new observations.

Testing Ultracool Models with Precise Luminosities and Masses

NASA Astrophysics Data System (ADS)

Dupuy, Trent; Cushing, Michael; Liu, Michael; Burningham, Ben; Leggett, Sandy; Albert, Loic; Delorme, Philippe

2011-05-01

After years of patient orbital monitoring, there is a growing sample of brown dwarfs with well-determined dynamical masses, representing the gold standard for testing substellar models. A key element of our model tests to date has been the use of integrated-light photometry to provide accurate total luminosity measurements for these binaries. However, some of the ultracool binaries with the most promising orbit motion for yielding dynamical in the masses lack the mid-infrared photometry needed to constrain their SEDs. This is especially crucial for the latest type binaries (spectral types >T5) that will probe the coldest temperature regimes previously untested with dynamical masses. We propose to use IRAC to obtain the needed mid-infrared photometry for a sample of binaries that are part of our ongoing orbital monitoring program with Keck laser guide star adaptive optics. The observational effort needed to characterize these binaries' luminosities using Spitzer is much less daunting in than the years of orbital monitoring needed to measure precise dynamical masses, but it is equally vital for robust tests of theory.

A Substellar Companion to Pleiades HII 3441

NASA Technical Reports Server (NTRS)

Konishi, Mihoko; Matsuo, Taro; Yamamoto, Kodai; Samland, Matthias; Sudo, Jun; Shibai, Hiroshi; Itoh, Yoichi; Fukagawa, Misato; Sumi, Takhiro; Kudo, Tomoyuki;

Tidal Interaction among Red Giants Close Binary Systems in APOGEE Database

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Majewski, Steven R.; Troup, Nicholas William; Weinberg, Nevin N.

2017-01-01

Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), the tidal evolution of binaries containing a red giant branch (RGB) star with a stellar or substellar companion was investigated. The tide raised by the companion in the RGB star leads to exchange of angular momentum between the orbit and the stellar spin, causing the orbit to contract. The tidal dissipation rate is computed using turbulent viscosity acting on the equilibrium tidal flow, where careful attention is paid to the effects of reduced viscosity for close-in companions. Evolutionary models for the RGB stars, from the zero-age main sequence to the present, were acquired from the MESA code. "Standard" turbulent viscosity gives rise to such a large orbital decay that many observed systems have decay times much shorter than the RGB evolution time. Several theories for "reduced" turbulent viscosity are investigated, and reduce the number of systems with uncomfortably short decay times.

The young, tight, and low-mass binary TWA22AB: a new calibrator for evolutionary models?. Orbit, spectral types, and temperature

NASA Astrophysics Data System (ADS)

Bonnefoy, M.; Chauvin, G.; Dumas, C.; Lagrange, A.-M.; Beust, H.; Desort, M.; Teixeira, R.; Ducourant, C.; Beuzit, J.-L.; Song, I.

2009-11-01

Context: Tight binaries discovered in young, nearby associations are ideal targets for providing dynamical mass measurements to test the physics of evolutionary models at young ages and very low masses. Aims: We report the binarity of TWA22 for the first time. We aim at monitoring the orbit of this young and tight system to determine its total dynamical mass using an accurate distance determination. We also intend to characterize the physical properties (luminosity, effective temperature, and surface gravity) of each component based on near-infrared photometric and spectroscopic observations. Methods: We used the adaptive-optics assisted imager NACO to resolve the components, to monitor the complete orbit and to obtain the relative near-infrared photometry of TWA22 AB. The adaptive-optics assisted integral field spectrometer SINFONI was also used to obtain medium-resolution (Rλ=1500-2000) spectra in JHK bands. Comparison with empirical and synthetic librairies were necessary for deriving the spectral type, the effective temperature, and the surface gravity for each component of the system. Results: Based on an accurate trigonometric distance (17.5 ± 0.2 pc) determination, we infer a total dynamical mass of 220 ± 21 MJup for the system. From the complete set of spectra, we find an effective temperature T_eff=2900+200-200 K for TWA22 A and T_eff=2900+200-100 K for TWA22 B and surface gravities between 4.0 and 5.5 dex. From our photometry and an M6 ± 1 spectral type for both components, we find luminosities of log(L/L⊙) = -2.11 ± 0.13 dex and log(L/L⊙) = -2.30 ± 0.16 dex for TWA22 A and B, respectively. By comparing these parameters with evolutionary models, we question the age and the multiplicity of this system. We also discuss a possible underestimation of the mass predicted by evolutionary models for young stars close to the substellar boundary. Based on service-mode observations (072.C-0644, 073.C-0469, 075.C-0521, 076.C-0554, 078.C-0510, 080.C-0581) collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norris, Jackson M.; Wright, Jason T.; Mahadevan, Suvrath

It has been argued that a substellar companion may significantly influence the evolution of the progenitors of subdwarf B (sdB) stars. Recently, the bright sdB star HD 149382 has been claimed to host a substellar (possibly planetary) companion with a period of 2.391 days. This has important implications for the evolution of the progenitors of sdB stars as well as the source of the UV excess seen in elliptical galaxies. In order to verify this putative companion, we made 10 radial velocity measurements of HD 149382 over 17 days with the High Resolution Spectrograph at the Hobby-Eberly Telescope. Our datamore » conclusively demonstrate that the putative substellar companion does not exist, and they exclude the presence of almost any substellar companion with P < 28 days and Msin i {approx}> 1 M{sub Jup}.« less

Photometric properties for selected algol-type binaries. VIII. The triple systems DI Peg and AF Gem revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yuan-Gui; Li, Shu-Zheng; Yang, Ying, E-mail: yygcn@163.com, E-mail: yangyg@chnu.edu.cn, E-mail: yangy818@yeah.net

2014-06-01

New extensive photometry for two triple binary stars, DI Peg and AF Gem, was performed from 2012 October to 2013 January, with two small telescopes at Xinglong station (XLs) of NAOC. From new multi-color observations and previously published ones in literature, the photometric models were (re)deduced using the updated Wilson-Devinney code. The results indicated that the low third lights exist in two classic Algol-type binaries, whose fill-out factors for the more massive components are f{sub p} = 78.2(± 0.4)% for DI Peg, and f{sub p} = 69.0(± 0.3)% for AF Gem, respectively. Through analyzing the O–C curves, the orbital periodsmore » for two binaries change in the complicated mode. The period of DI Peg possibly appears to show two light-time orbits, whose modulated periods are P {sub 3} = 54.6(± 0.5) yr and P {sub 4} = 23.0(± 0.6) yr, respectively. The inferred minimum masses for the inner and outer sub-stellar companions are M {sub in} = 0.095 M {sub ☉} and M {sub out} = 0.170 M {sub ☉}, respectively. Therefore, DI Peg may be a quadruple star. The orbital period of AF Gem appears to show a continuous period decrease or a cyclic variation; the latter may be preferable. The cyclic oscillation, with a period of 120.3(± 2.5) yr, may be attributed to the light-time effect due to the third body. This kind of additional companion may extract angular momentum from the central system, which may play a key role in the evolution of the binary.« less

DISCOVERY OF A HIGHLY UNEQUAL-MASS BINARY T DWARF WITH KECK LASER GUIDE STAR ADAPTIVE OPTICS: A COEVALITY TEST OF SUBSTELLAR THEORETICAL MODELS AND EFFECTIVE TEMPERATURES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Michael C.; Dupuy, Trent J.; Leggett, S. K., E-mail: mliu@ifa.hawaii.ed

Highly unequal-mass ratio binaries are rare among field brown dwarfs, with the mass ratio distribution of the known census described by q {sup (4.9{+-}0.7)}. However, such systems enable a unique test of the joint accuracy of evolutionary and atmospheric models, under the constraint of coevality for the individual components (the 'isochrone test'). We carry out this test using two of the most extreme field substellar binaries currently known, the T1 + T6 {epsilon} Ind Bab binary and a newly discovered 0.''14 T2.0 + T7.5 binary, 2MASS J12095613-1004008AB, identified with Keck laser guide star adaptive optics. The latter is the mostmore » extreme tight binary resolved to date (q {approx} 0.5). Based on the locations of the binary components on the Hertzsprung-Russell (H-R) diagram, current models successfully indicate that these two systems are coeval, with internal age differences of log(age) = -0.8 {+-} 1.3(-1.0{sup +1.2}{sub -1.3}) dex and 0.5{sup +0.4}{sub -0.3}(0.3{sup +0.3}{sub -0.4}) dex for 2MASS J1209-1004AB and {epsilon} Ind Bab, respectively, as inferred from the Lyon (Tucson) models. However, the total mass of {epsilon} Ind Bab derived from the H-R diagram ({approx} 80 M{sub Jup} using the Lyon models) is strongly discrepant with the reported dynamical mass. This problem, which is independent of the assumed age of the {epsilon} Ind Bab system, can be explained by a {approx} 50-100 K systematic error in the model atmosphere fitting, indicating slightly warmer temperatures for both components; bringing the mass determinations from the H-R diagram and the visual orbit into consistency leads to an inferred age of {approx} 6 Gyr for {epsilon} Ind Bab, older than previously assumed. Overall, the two T dwarf binaries studied here, along with recent results from T dwarfs in age and mass benchmark systems, yield evidence for small ({approx}100 K) errors in the evolutionary models and/or model atmospheres, but not significantly larger. Future parallax, resolved spectroscopy, and dynamical mass measurements for 2MASS J1209-1004AB will enable a more stringent application of the isochrone test. Finally, the binary nature of this object reduces its utility as the primary T3 near-IR spectral typing standard; we suggest SDSS J1206+2813 as a replacement.« less

The Unevenly Distributed Nearest Brown Dwarfs

NASA Astrophysics Data System (ADS)

Bihain, Gabriel; Scholz, Ralf-Dieter

2016-08-01

To address the questions of how many brown dwarfs there are in the Milky Way, how do these objects relate to star formation, and whether the brown dwarf formation rate was different in the past, the star-to-brown dwarf number ratio can be considered. While main sequence stars are well known components of the solar neighborhood, lower mass, substellar objects increasingly add to the census of the nearest objects. The sky projection of the known objects at <6.5 pc shows that stars present a uniform distribution and brown dwarfs a non-uniform distribution, with about four times more brown dwarfs behind than ahead of the Sun relative to the direction of rotation of the Galaxy. Assuming that substellar objects distribute uniformly, their observed configuration has a probability of 0.1 %. The helio- and geocentricity of the configuration suggests that it probably results from an observational bias, which if compensated for by future discoveries, would bring the star-to-brown dwarf ratio in agreement with the average ratio found in star forming regions.

Very Low-mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

NASA Astrophysics Data System (ADS)

Ma, Bo; Ge, Jian; Wolszczan, Alex; Muterspaugh, Matthew W.; Lee, Brian; Henry, Gregory W.; Schneider, Donald P.; Martín, Eduardo L.; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W.; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; Nicolaci da Costa, Luiz; Jiang, Peng; Martinez Fiorenzano, A. F.; González Hernández, Jonay I.; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C.; Wan, Xiaoke; Wang, Ji; Wisniewski, John P.; Zhao, Bo; Zucker, Shay

2016-11-01

We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using the Exoplanet Tracker at the Kitt Peak National Observatory, the High Resolution Spectrograph at the Hobby Eberley telescope, the “Classic” spectrograph at the Automatic Spectroscopic Telescope at the Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period BD in this binary. HD 87646 is a close binary with a separation of ˜22 au between the two stars, estimated using the Hipparcos catalog and our newly acquired AO image from PALAO on the 200 inch Hale Telescope at Palomar. The primary star in the binary, HD 87646A, has {T}{eff} = 5770 ± 80 K, log g = 4.1 ± 0.1, and [Fe/H] = -0.17 ± 0.08. The derived minimum masses of the two substellar companions of HD 87646A are 12.4 ± 0.7 {M}{Jup} and 57.0 ± 3.7 {M}{Jup}. The periods are 13.481 ± 0.001 days and 674 ± 4 days and the measured eccentricities are 0.05 ± 0.02 and 0.50 ± 0.02 respectively. Our dynamical simulations show that the system is stable if the binary orbit has a large semimajor axis and a low eccentricity, which can be verified with future astrometry observations.

Discovery of a Very Low Mass Triple with Late-M and T Dwarf Components: LP 704-48/SDSS J0006-0852AB

NASA Astrophysics Data System (ADS)

Burgasser, Adam J.; Luk, Christopher; Dhital, Saurav; Bardalez Gagliuffi, Daniella; Nicholls, Christine P.; Prato, L.; West, Andrew A.; Lépine, Sébastien

2012-10-01

We report the identification of the M9 dwarf SDSS J000649.16-085246.3 as a spectral binary and radial velocity (RV) variable with components straddling the hydrogen-burning mass limit. Low-resolution near-infrared spectroscopy reveals spectral features indicative of a T dwarf companion, and spectral template fitting yields component types of M8.5 ± 0.5 and T5 ± 1. High-resolution near-infrared spectroscopy with Keck/NIRSPEC reveals pronounced RV variations with a semi-amplitude of 8.2 ± 0.4 km s-1. From these we determine an orbital period of 147.6 ± 1.5 days and eccentricity of 0.10 ± 0.07, making SDSS J0006-0852AB the third tightest very low mass binary known. This system is also found to have a common proper motion companion, the inactive M7 dwarf LP 704-48, at a projected separation of 820 ± 120 AU. The lack of Hα emission in both M dwarf components indicates that this system is relatively old, as confirmed by evolutionary model analysis of the tight binary. LP 704-48/SDSS J0006-0852AB is the lowest-mass confirmed triple identified to date, and one of only seven candidate and confirmed triples with total masses below 0.3 M ⊙ currently known. We show that current star and brown dwarf formation models cannot produce triple systems like LP 704-48/SDSS J0006-0852AB, and we rule out Kozai-Lidov perturbations and tidal circularization as a viable mechanism to shrink the inner orbit. The similarities between this system and the recently uncovered low-mass eclipsing triples NLTT 41135AB/41136 and LHS 6343ABC suggest that substellar tertiaries may be common in wide M dwarf pairs. Portions of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The GAPS Programme with HARPS-N at TNG. XV. A substellar companion around a K giant star identified with quasi-simultaneous HARPS-N and GIANO measurements

NASA Astrophysics Data System (ADS)

González-Álvarez, E.; Affer, L.; Micela, G.; Maldonado, J.; Carleo, I.; Damasso, M.; D'Orazi, V.; Lanza, A. F.; Biazzo, K.; Poretti, E.; Gratton, R.; Sozzetti, A.; Desidera, S.; Sanna, N.; Harutyunyan, A.; Massi, F.; Oliva, E.; Claudi, R.; Cosentino, R.; Covino, E.; Maggio, A.; Masiero, S.; Molinari, E.; Pagano, I.; Piotto, G.; Smareglia, R.; Benatti, S.; Bonomo, A. S.; Borsa, F.; Esposito, M.; Giacobbe, P.; Malavolta, L.; Martinez-Fiorenzano, A.; Nascimbeni, V.; Pedani, M.; Rainer, M.; Scandariato, G.

2017-10-01

Context. Identification of planetary companions of giant stars is made difficult because of the astrophysical noise, that may produce radial velocity variations similar to those induced by a companion. On the other hand any stellar signal is wavelength dependent, while signals due to a companion are achromatic. Aims: Our goal is to determine the origin of the Doppler periodic variations observed in the thick disk K giant star TYC 4282-605-1 by HARPS-N at the Telescopio Nazionale Galileo (TNG) and verify if they can be due to the presence of a substellar companion. Methods: Several methods have been used to exclude the stellar origin of the observed signal including detailed analysis of activity indicators and bisector and the analysis of the photometric light curve. Finally we have conducted an observational campaign to monitor the near infrared (NIR) radial velocity with GIANO at the TNG in order to verify whether the NIR amplitude variations are comparable with those observed in the visible. Results: Both optical and NIR radial velocities show consistent variations with a period at 101 days and similar amplitude, pointing to the presence of a companion orbiting the target. The main orbital properties obtained for our giant star with a derived mass of M = 0.97 ± 0.03M⊙ are MPsini = 10.78 ± 0.12MJ; P = 101.54 ± 0.05 days; e = 0.28 ± 0.01 and a = 0.422 ± 0.009 AU. The chemical analysis shows a significant enrichment in the abundance of Na I, Mg I, Al I and Si I while the rest of analyzed elements are consistent with the solar value demonstrating that the chemical composition corresponds with an old K giant (age = 10.1 Gyr) belonging to local thick disk. Conclusions: We conclude that the substellar companion hypothesis for this K giant is the best explanation for the observed periodic radial velocity variation. This study also shows the high potential of multi-wavelength radial velocity observations for the validation of planet candidates. Based on observations collected at the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the frame of the programme Global Architecture of Planetary Systems (GAPS).

Digging for substellar objects in the stellar graveyard

NASA Astrophysics Data System (ADS)

Debes, John H., IV

2005-11-01

White dwarfs, the endpoint of stellar evolution for stars with mass < 8 [Special characters omitted.] , possess several attributes favorable for studying planet and brown dwarf formation around stars with primordial masses 1 [Special characters omitted.] . This thesis explores the consequences of post-main-sequence evolution on the dynamics of a planetary system and the observational signatures that arise from such evolution. These signatures are then specifically tested with a direct imaging survey of nearby white dwarfs. Finally, new techniques for high contrast imaging are discussed and placed in the context of further searches for planets and brown dwarfs in the stellar graveyard. While planets closer than ~ 5 AU will most likely not survive the post-main sequence evolution of its parent star, any planet with semimajor axis > 5 AU will survive, and its semimajor axis will increase as the central star loses mass. The stability of adjacent orbits to mutual planet-planet perturbations depends on the ratio of the planet mass to the central star's mass, and I demonstrate that some planets in previously stable orbits around a star undergoing mass loss will become unstable. If pollution of a white dwarf's atmosphere is caused by relic planetary systems, any white dwarf with photospheric absorption due to metals can be searched for substellar companions. Hydrogen white dwarfs with metal absorption, so called DAZ white dwarfs, are hard to explain by simple ISM accretion, and present an opportunity to test the observational signatures of unstable planetary systems. Additionally, field white dwarfs can be searched for substellar companions as well. The search for planetary companions to stars requires further development of high contrast imaging techniques. This thesis studies Gaussian aperture pupil masks (GAPMs) which in theory can achieve the contrast requisite for directly imaging an extrasolar planet around a nearby solar type star. I outline the process of designing, fabricating, and testing a GAPM for use on current telescopes and specifically the Penn State near-IR Imager and Spectrograph (PIRIS) at the Mt. Wilson 100" telescope. I find that observations with a prototype are quite successful, achieving a contrast similar to a traditional Lyot coronagraph without blocking any light from a central object and useful for finding faint companions to nearby young solar analogues. In the lab I can reproduce the expected PSF reasonably well and with a single aperture design which achieves ~ 4 x 10 -5 contrast at 10l/ D . I find that small inaccuracies in the mask fabrication process and insufficient correction of the atmosphere contribute the most degradation to contrast at these levels. (Abstract shortened by UMI.)

A SUBSTELLAR COMPANION TO THE DUSTY PLEIADES STAR HD 23514

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, David R.; Zuckerman, B.; Marois, Christian

2012-03-20

With adaptive optics imaging at Keck observatory, we have discovered a substellar companion to the F6 Pleiades star HD 23514, one of the dustiest main-sequence stars known to date (L{sub IR}/L{sub *} {approx} 2%). This is one of the first brown dwarfs discovered as a companion to a star in the Pleiades. The 0.06 M{sub Sun} late-M secondary has a projected separation of {approx}360 AU. The scarcity of substellar companions to stellar primaries in the Pleiades combined with the extremely dusty environment make this a unique system to study.

Exploring the brown dwarf desert: new substellar companions from the SDSS-III MARVELS survey

NASA Astrophysics Data System (ADS)

Grieves, Nolan; Ge, Jian; Thomas, Neil; Ma, Bo; Sithajan, Sirinrat; Ghezzi, Luan; Kimock, Ben; Willis, Kevin; De Lee, Nathan; Lee, Brian; Fleming, Scott W.; Agol, Eric; Troup, Nicholas; Paegert, Martin; Schneider, Donald P.; Stassun, Keivan; Varosi, Frank; Zhao, Bo; Jian, Liu; Li, Rui; Porto de Mello, Gustavo F.; Bizyaev, Dmitry; Pan, Kaike; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Santiago, Basílio X.; da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; del Peloso, E. F.

2017-06-01

Planet searches using the radial velocity technique show a paucity of companions to solar-type stars within ˜5 au in the mass range of ˜10-80 MJup. This deficit, known as the brown dwarf desert, currently has no conclusive explanation. New substellar companions in this region help assess the reality of the desert and provide insight to the formation and evolution of these objects. Here, we present 10 new brown dwarf and 2 low-mass stellar companion candidates around solar-type stars from the Multi-object APO Radial Velocity Exoplanet Large-Area Survey (MARVELS) of the Sloan Digital Sky Survey III. These companions were selected from processed MARVELS data using the latest University of Florida Two Dimensional pipeline, which shows significant improvement and reduction of systematic errors over previous pipelines. The 10 brown dwarf companions range in mass from ˜13 to 76 MJup and have orbital radii of less than 1 au. The two stellar companions have minimum masses of ˜98 and 100 MJup. The host stars of the MARVELS brown dwarf sample have a mean metallicity of [Fe/H] = 0.03 ± 0.08 dex. Given our stellar sample we estimate the brown dwarf occurrence rate around solar-type stars with periods less than ˜300 d to be ˜0.56 per cent.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, S.-B.; Zhu, L.-Y.; Liao, W.-P.

HS 0705+6700 is a short-period (P = 2.3 hr), close binary containing a hot sdB-type primary and a fully convective secondary. We have monitored this eclipsing binary for more than two years and as a result, 32 times of light minimum were obtained. Based on our new eclipse times together with these compiled from the literature, it is discovered that the observed-calculated curve of HS 0705+6700 shows a cyclic variation with a period of 7.15 years and a semiamplitude of 92.4 s. The periodic change was analyzed for the light-travel time effect that may be due to the presence ofmore » a tertiary companion. The mass of the third body is determined to be M {sub 3}sin i' = 0.0377({+-}0.0043) M {sub sun} when a total mass of 0.617 M {sub sun} for HS 0705+6700 is adopted. For orbital inclinations i' {>=} 32.{sup 0}8, the mass of the tertiary component would be below the stable hydrogen-burning limit of M {sub 3} {approx} 0.072 M {sub sun}, and thus it would be a brown dwarf. The third body is orbiting the sdB-type binary at a distance shorter than 3.6 AU. HS 0705+6700 was formed through the evolution of a common envelope after the primary becomes a red giant. The detection of a substellar companion in HS 0705+6700 system at this distance from the binary could give some constraints on stellar evolution in such systems and the interactions between red giants and their companions.« less

The Exoplanet Simple Orbit Fitting Toolbox (ExoSOFT): An Open-source Tool for Efficient Fitting of Astrometric and Radial Velocity Data

NASA Astrophysics Data System (ADS)

Mede, Kyle; Brandt, Timothy D.

2017-03-01

We present the Exoplanet Simple Orbit Fitting Toolbox (ExoSOFT), a new, open-source suite to fit the orbital elements of planetary or stellar-mass companions to any combination of radial velocity and astrometric data. To explore the parameter space of Keplerian models, ExoSOFT may be operated with its own multistage sampling approach or interfaced with third-party tools such as emcee. In addition, ExoSOFT is packaged with a collection of post-processing tools to analyze and summarize the results. Although only a few systems have been observed with both radial velocity and direct imaging techniques, this number will increase, thanks to upcoming spacecraft and ground-based surveys. Providing both forms of data enables simultaneous fitting that can help break degeneracies in the orbital elements that arise when only one data type is available. The dynamical mass estimates this approach can produce are important when investigating the formation mechanisms and subsequent evolution of substellar companions. ExoSOFT was verified through fitting to artificial data and was implemented using the Python and Cython programming languages; it is available for public download at https://github.com/kylemede/ExoSOFT under GNU General Public License v3.

MUCHFUSS - Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS

NASA Astrophysics Data System (ADS)

Geier, S.; Schaffenroth, V.; Hirsch, H.; Tillich, A.; Heber, U.; Maxted, P. F. L.; Østensen, R. H.; Barlow, B. N.; O'Toole, S. J.; Kupfer, T.; Marsh, T.; Gänsicke, B.; Napiwotzki, R.; Cordes, O.; Müller, S.; Classen, L.; Ziegerer, E.; Drechsel, H.

2012-06-01

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (white dwarfs with masses M>1.0 M⊙, neutron stars or black holes). The existence of such systems is predicted by binary evolution calculations and some candidate systems have been found. We identified ≃1100 hot subdwarf stars from the Sloan Digital Sky Survey (SDSS). Stars with high velocities have been reobserved and individual SDSS spectra have been analysed. About 70 radial velocity variable subdwarfs have been selected as good candidates for follow-up time resolved spectroscopy to derive orbital parameters and photometric follow-up to search for features like eclipses in the light curves. Up to now we found nine close binary sdBs with short orbital periods ranging from ≃0.07 d to 1.5 d. Two of them are eclipsing binaries with companions that are most likely of substellar nature.

Testing the Formation Mechanism of Sub-Stellar Objects in Lupus (A SOLA Team Study)

NASA Astrophysics Data System (ADS)

De Gregorio-Monsalvo, Itziar; Lopez, C.; Takahashi, S.; Santamaria-Miranda

2017-06-01

The international SOLA team (Soul of Lupus with ALMA) has identified a set of pre- and proto-stellar candidates in Lupus 1 and 3 of substellar nature using 1.1mm ASTE/AzTEC maps and our optical to submillimeter database. We have observed with ALMA the most promising pre- and proto-brown dwarfs candidates. Our aims are to provide insights on how substellar objects form and evolve, from the equivalent to the pre-stellar cores to the Class II stage in the low mass regime of star formation. Our sample comprises 33 pre-stellar objects, 7 Class 0 and I objects, and 22 Class II objects.

Finding the elusive substellar members of young moving groups

NASA Astrophysics Data System (ADS)

Aller, Kimberly Mei

Young moving groups (YMGs) consist of coeval, comoving stars, with ages between 10-100Myrs, that have migrated from their origins after formation. They provide a valuable link between ongoing star formation in molecular clouds (˜1Myr) and old field stars (≥1Gyr). However, previous searches based on optical surveys such as Hipparcos and the Palomar Sky Survey were insensitive to these very faint cool dwarfs. More recent surveys with GALEX have begun to reveal the nearby (<25 pc) low-mass members (≥ 0.1 M solar massses) but the cool, substellar members have remained elusive. We have increased the search volume by a factor of ˜10 using a novel combination of photometry and proper motions from Pan-STARRS, WISE, and 2MASS in order to uncover the missing substellar members down to ≥ 00.1 M solar massses (at 10Myr). We have obtained NIR low-resolution spectroscopy and confirmed the youth of 65 new ultracool dwarf YMG candidates. We also obtained high-resolution NIR spectroscopy to determine radial velocities for our young brown dwarfs. With our RVs and PS1 parallaxes, we have nearly doubled the number of confirmed bona fide substellar YMG members, which are also brown dwarf age benchmarks. Our new young brown dwarfs empirically define the substellar spectral evolution with age and provide us with a snapshot of brown dwarf evolution. Finally, our resulting young brown dwarfs will be valuable targets for future surveys of brown dwarf binarity and young exoplanet characterization.

Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering

NASA Astrophysics Data System (ADS)

Stark, C. R.; Diver, D. A.

2018-04-01

Context. In contemporary sub-stellar model atmospheres, dust growth occurs through neutral gas-phase surface chemistry. Recently, there has been a growing body of theoretical and observational evidence suggesting that ionisation processes can also occur. As a result, atmospheres are populated by regions composed of plasma, gas and dust, and the consequent influence of plasma processes on dust evolution is enhanced. Aim. This paper aims to introduce a new model of dust growth and destruction in sub-stellar atmospheres via plasma deposition and plasma sputtering. Methods: Using example sub-stellar atmospheres from DRIFT-PHOENIX, we have compared plasma deposition and sputtering timescales to those from neutral gas-phase surface chemistry to ascertain their regimes of influence. We calculated the plasma sputtering yield and discuss the circumstances where plasma sputtering dominates over deposition. Results: Within the highest dust density cloud regions, plasma deposition and sputtering dominates over neutral gas-phase surface chemistry if the degree of ionisation is ≳10-4. Loosely bound grains with surface binding energies of the order of 0.1-1 eV are susceptible to destruction through plasma sputtering for feasible degrees of ionisation and electron temperatures; whereas, strong crystalline grains with binding energies of the order 10 eV are resistant to sputtering. Conclusions: The mathematical framework outlined sets the foundation for the inclusion of plasma deposition and plasma sputtering in global dust cloud formation models of sub-stellar atmospheres.

The MUCHFUSS photometric campaign

NASA Astrophysics Data System (ADS)

Schaffenroth, V.; Geier, S.; Heber, U.; Gerber, R.; Schneider, D.; Ziegerer, E.; Cordes, O.

2018-06-01

Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which have lost almost all of their hydrogen envelope. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool companions like late-type stars or brown dwarfs are detectable via characteristic light-curve variations like reflection effects and often also eclipses. To search for such objects, we obtained multi-band light curves of 26 close sdO/B binary candidates from the MUCHFUSS project with the BUSCA instrument. We discovered a new eclipsing reflection effect system (P = 0.168938 d) with a low-mass M dwarf companion (0.116 M⊙). Three more reflection effect binaries found in the course of the campaign have already been published; two of them are eclipsing systems, and in one system only showing the reflection effect but no eclipses, the sdB primary is found to be pulsating. Amongst the targets without reflection effect a new long-period sdB pulsator was discovered and irregular light variations were found in two sdO stars. The found light variations allowed us to constrain the fraction of reflection effect binaries and the substellar companion fraction around sdB stars. The minimum fraction of reflection effect systems amongst the close sdB binaries might be greater than 15% and the fraction of close substellar companions in sdB binaries may be as high as 8.0%. This would result in a close substellar companion fraction to sdB stars of about 3%. This fraction is much higher than the fraction of brown dwarfs around possible progenitor systems, which are solar-type stars with substellar companions around 1 AU, as well as close binary white dwarfs with brown dwarf companions. This might suggest that common envelope interactions with substellar objects are preferentially followed by a hot subdwarf phase.

VERY LOW MASS STELLAR AND SUBSTELLAR COMPANIONS TO SOLAR-LIKE STARS FROM MARVELS. I. A LOW-MASS RATIO STELLAR COMPANION TO TYC 4110-01037-1 IN A 79 DAY ORBIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wisniewski, John P.; Agol, Eric; Barnes, Rory

TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and short orbital period are atypical among binary systems with solar-like (T{sub eff} {approx}< 6000 K) primary stars. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged ({approx}<5 Gyr) solar-like star having a mass of 1.07 {+-} 0.08 M{sub Sun} and radius of 0.99 {+-} 0.18 R{sub Sun }. We analyze 32 radial velocity (RV) measurements from the SDSS-III MARVELS survey as well as 6 supporting RV measurements from the SARG spectrograph on the 3.6 m Telescopio Nazionale Galileo telescope obtained over a period of {approx}2more » years. The best Keplerian orbital fit parameters were found to have a period of 78.994 {+-} 0.012 days, an eccentricity of 0.1095 {+-} 0.0023, and a semi-amplitude of 4199 {+-} 11 m s{sup -1}. We determine the minimum companion mass (if sin i = 1) to be 97.7 {+-} 5.8 M{sub Jup}. The system's companion to host star mass ratio, {>=}0.087 {+-} 0.003, places it at the lowest end of observed values for short period stellar companions to solar-like (T{sub eff} {approx}< 6000 K) stars. One possible way to create such a system would be if a triple-component stellar multiple broke up into a short period, low q binary during the cluster dispersal phase of its lifetime. A candidate tertiary body has been identified in the system via single-epoch, high contrast imagery. If this object is confirmed to be comoving, we estimate it would be a dM4 star. We present these results in the context of our larger-scale effort to constrain the statistics of low-mass stellar and brown dwarf companions to FGK-type stars via the MARVELS survey.« less

Exploring Substellar Evolution with the Coldest Brown Dwarfs

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.

2017-01-01

The coldest brown dwarfs are our best analogs to extrasolar gas-giant planets, representing the lowest mass products of star formation. Our view of such objects has been transformed over the last few years as new observations have revealed that the solar neighborhood is populated by much colder objects than previously recognized. At the center of efforts to discover and characterize these coldest substellar objects have been observations from NASA missions (WISE, Spitzer, HST) and the Keck Telescopes. I will review the tremendous progress made in this field over just the last few years thanks to major community efforts to overcome observational challenges in obtaining spectroscopy, photometry, and astrometry of these infrared-faint, optically invisible objects. Spectra from HST and Keck were key in establishing the much anticipated "Y" spectral type, extending the classic stellar classification scheme to atmospheres as cool as 300-400 K. Parallaxes and photometry from Spitzer and Keck have provided absolute fluxes, enabling robust temperature determinations and critical tests of model atmopheres. High-resolution imaging with Keck laser guide star adaptive optics (LGS AO) has been the most prolific resource for revealing tight companions among the coldest brown dwarfs. In fact, with continued orbit monitoring with Keck LGS AO and HST, these binary systems will ultimately provide dynamical masses that will allow the strongest tests of models and reveal if the coldest brown dwarfs are indeed "planetary mass" (less than about 13 Jupiter masses) as is currently thought.

Getting to know the nearest stars: Intermittent radio bursts from Ross 614

NASA Astrophysics Data System (ADS)

Winterhalter, Daniel; Knapp, Mary; Bastian, Tim

2017-04-01

Radio observations have been used as a search tool for exoplanets since before the confirmed discovery of the first extrasolar planet. To date, there have been no definitive detections of exoplanets in the radio regime. We are engaged in an ongoing blind radio survey of the nearest star systems for exoplanetary radio emission. The goal of this survey is to obtain meaningful upper limits on radio emission from (or modulated by) sub-stellar companions of the nearest stars. Nearby stars are strongly preferred because they suffer the least from the dilution of potential radio signals by distance. Targets are selected by distance and observability (both LOFAR and VLA) only. Other properties of target stars, such as stellar type, are not considered to avoid biasing the search. Five survey targets, Procyon, GJ 1111, GJ 725, Ross 614, and UGPSJ072227.51, have been observed with the VLA telescope L- and S-band receivers. P-band observations are ongoing. Of particular interest are, at this time, our observation of the Ross 614 System. Ross 614 is an M-dwarf binary system at a distance of about 13 Ly, with an orbital period of 16.6 years. The binary companions are classified as flare stars because strong radio emission has been detected from the location of the system in previous work. Analyses are in progress to determine if the intermittent burst are similar to solar-type burst, and/or if there is any evidence for emissions from sub-stellar companions.

Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Gao, Peter; Marley, Mark S.; Ackerman, Andrew S.

2018-03-01

Condensation clouds in substellar atmospheres have been widely inferred from spectra and photometric variability. Up until now, their horizontally averaged vertical distribution and mean particle size have been largely characterized using models, one of which is the eddy diffusion–sedimentation model from Ackerman and Marley that relies on a sedimentation efficiency parameter, f sed, to determine the vertical extent of clouds in the atmosphere. However, the physical processes controlling the vertical structure of clouds in substellar atmospheres are not well understood. In this work, we derive trends in f sed across a large range of eddy diffusivities (K zz ), gravities, material properties, and cloud formation pathways by fitting cloud distributions calculated by a more detailed cloud microphysics model. We find that f sed is dependent on K zz , but not gravity, when K zz is held constant. f sed is most sensitive to the nucleation rate of cloud particles, as determined by material properties like surface energy and molecular weight. High surface energy materials form fewer, larger cloud particles, leading to large f sed (>1), and vice versa for materials with low surface energy. For cloud formation via heterogeneous nucleation, f sed is sensitive to the condensation nuclei flux and radius, connecting cloud formation in substellar atmospheres to the objects’ formation environments and other atmospheric aerosols. These insights could lead to improved cloud models that help us better understand substellar atmospheres. For example, we demonstrate that f sed could increase with increasing cloud base depth in an atmosphere, shedding light on the nature of the brown dwarf L/T transition.

Spectral comparison of directly imaged, young substellar companions using integral field spectroscopy - construction of an empiric log g sequence

NASA Astrophysics Data System (ADS)

Schmidt, T.; Neuhaüser, R.; Seifahrt, A.

2010-10-01

About 15 substellar companions with large separations (>∼50 AU) to their young primary stars and brown dwarfs are confirmed by both common proper motion and late-M / early-L type spectra. The origin and early evolution of these objects is still under debate. While often these substellar companions are regarded as brown dwarfs, they could possibly also be massive planets, the mass estimates are very uncertain so far. They are companions to primary stars or brown dwarfs in young associations and star forming regions like the TW Hya association, Upper Scorpius, Taurus, Beta Pic moving group, TucHor association, Lupus, Ophiuchus, and Chamaeleon, hence their ages and distances are well known, in contrast to free-floating brown dwarfs. An empirical classification is not possible, because a spectral sequence that is taking the lower gravity into account, is not existing. This problem leads to an apparent mismatch between spectra of old field type objects and young low-mass companions at the same effective temperature, hampering a determination of temperature and surface gravity independent from models. Now that about 15 such substellar candidates are found in associations of different ages, 1 - 35 Myrs, it is possible to study their spectra in comparison to each other using the advantage of light concentration by an adaptive optics system with their primary as guide star. Therefore we have begun the construction of an empirical log g sequence from beginning to observe all these substellar companions homogeneously using the AO-assisted integral field spectrograph SINFONI at VLT (ESO).

Spectroscopic and Photometric Analysis of the HW Vir Star PTF1 J011339.09+225739.1

NASA Astrophysics Data System (ADS)

Wolz, Maximilian; Kupfer, Thomas; Drechsel, Horst; Heber, Ulrich; Irrgang, Andreas; Hermes, J. J.; Bloemen, Steven; Levitan, David; Dhillon, Vik; Marsh, TomR.

2018-05-01

HW Vir systems are rare eclipsing binary systems including a subdwarf B star (sdB) with a faint companion, mostly M-dwarfs. Up to now, 19 HW Vir systems have been published, three of them with substellar companions. We report the spectroscopic as well as photometric observation of the eclipsing sdB binary PTF1 J011339.09+225739.1 (PTF1 J0113) in a close (a=0.722 ± 0.023 R⊙), short period (P = 0.0933731(3)d) orbit. A quantitative spectral analysis of the sdB yields Te.=29280 ± 720 K, log(g)=5.77 ± 0.09 dex, and log(y)=-2.32 ± 0.12. The circular orbital velocity of the sdB of K1=74.2 ± 1.7 km s-1 is derived from the radial velocity curve. Except for the strong reflection effect, no other light contribution of the companion could be detected. The light curves - recorded with ULTRACAM - were analyzed using the Wilson-Devinney code. We find an inclination angle of i=79.88 ± 0.18∘. Because our first attempts to determine q failed, we calculated large grids of synthetic lightcurves for several mass ratios. Because of degeneracy, good solutions for different mass ratios were found - the one at q = 0.24 is consistent with the sdB's canonical mass (MsdB = 0.47 M⊙). Accordingly, the mass of the companion is M2=0.112 ± 0.003 M⊙. The radii of the two components were also derived: RsdB=0.178 ± 0.006 R⊙ and R2 = 0.158 ± 0.009 R⊙. Thus, the results for the secondary are consistent with an M-dwarf as secondary

Reconnaissance of the HR 8799 Exosolar System. II. Astrometry and Orbital Motion

NASA Astrophysics Data System (ADS)

Pueyo, L.; Soummer, R.; Hoffmann, J.; Oppenheimer, R.; Graham, J. R.; Zimmerman, N.; Zhai, C.; Wallace, J. K.; Vescelus, F.; Veicht, A.; Vasisht, G.; Truong, T.; Sivaramakrishnan, A.; Shao, M.; Roberts, L. C., Jr.; Roberts, J. E.; Rice, E.; Parry, I. R.; Nilsson, R.; Lockhart, T.; Ligon, E. R.; King, D.; Hinkley, S.; Hillenbrand, L.; Hale, D.; Dekany, R.; Crepp, J. R.; Cady, E.; Burruss, R.; Brenner, D.; Beichman, C.; Baranec, C.

2015-04-01

We present an analysis of the orbital motion of the four substellar objects orbiting HR 8799. Our study relies on the published astrometric history of this system augmented with an epoch obtained with the Project 1640 coronagraph with an integral field spectrograph (IFS) installed at the Palomar Hale telescope. We first focus on the intricacies associated with astrometric estimation using the combination of an extreme adaptive optics system (PALM-3000), a coronagraph, and an IFS. We introduce two new algorithms. The first one retrieves the stellar focal plane position when the star is occulted by a coronagraphic stop. The second one yields precise astrometric and spectrophotometric estimates of faint point sources even when they are initially buried in the speckle noise. The second part of our paper is devoted to studying orbital motion in this system. In order to complement the orbital architectures discussed in the literature, we determine an ensemble of likely Keplerian orbits for HR 8799bcde, using a Bayesian analysis with maximally vague priors regarding the overall configuration of the system. Although the astrometric history is currently too scarce to formally rule out coplanarity, HR 8799d appears to be misaligned with respect to the most likely planes of HR 8799bce orbits. This misalignment is sufficient to question the strictly coplanar assumption made by various authors when identifying a Laplace resonance as a potential architecture. Finally, we establish a high likelihood that HR 8799de have dynamical masses below 13 MJup, using a loose dynamical survival argument based on geometric close encounters. We illustrate how future dynamical analyses will further constrain dynamical masses in the entire system.

Fragment Production and Survival in Irradiated Disks: A Comprehensive Cooling Criterion

NASA Astrophysics Data System (ADS)

Kratter, Kaitlin M.; Murray-Clay, Ruth A.

2011-10-01

Accretion disks that become gravitationally unstable can fragment into stellar or substellar companions. The formation and survival of these fragments depends on the precarious balance between self-gravity, internal pressure, tidal shearing, and rotation. Disk fragmentation depends on two key factors: (1) whether the disk can get to the fragmentation boundary of Q = 1 and (2) whether fragments can survive for many orbital periods. Previous work suggests that to reach Q = 1, and have fragments survive, a disk must cool on an orbital timescale. Here we show that disks heated primarily by external irradiation always satisfy the standard cooling time criterion. Thus, even though irradiation heats disks and makes them more stable in general, once they reach the fragmentation boundary, they fragment more easily. We derive a new cooling criterion that determines fragment survival and calculate a pressure-modified Hill radius, which sets the maximum size of pressure-supported objects in a Keplerian disk. We conclude that fragmentation in protostellar disks might occur at slightly smaller radii than previously thought and recommend tests for future simulations that will better predict the outcome of fragmentation in real disks.

A brown dwarf mass donor in an accreting binary.

PubMed

Littlefair, S P; Dhillon, V S; Marsh, T R; Gänsicke, Boris T; Southworth, John; Watson, C A

2006-12-08

A long-standing and unverified prediction of binary star evolution theory is the existence of a population of white dwarfs accreting from substellar donor stars. Such systems ought to be common, but the difficulty of finding them, combined with the challenge of detecting the donor against the light from accretion, means that no donor star to date has a measured mass below the hydrogen burning limit. We applied a technique that allowed us to reliably measure the mass of the unseen donor star in eclipsing systems. We were able to identify a brown dwarf donor star, with a mass of 0.052 +/- 0.002 solar mass. The relatively high mass of the donor star for its orbital period suggests that current evolutionary models may underestimate the radii of brown dwarfs.

Spectroscopic binaries in the Solar Twin Planet Search program: from substellar-mass to M dwarf companions

NASA Astrophysics Data System (ADS)

dos Santos, Leonardo A.; Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Spina, Lorenzo; Alves-Brito, Alan; Dreizler, Stefan; Ramírez, Iván; Asplund, Martin

2017-12-01

Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do not obey this relation, often by displaying enhanced rotational rates and activity. In the Solar Twin Planet Search program, we observed several solar twin binaries, and found a multiplicity fraction of 42 per cent ± 6 per cent in the whole sample; moreover, at least three of these binaries (HIP 19911, HIP 67620 and HIP 103983) clearly exhibit the aforementioned anomalies. We investigated the configuration of the binaries in the program, and discovered new companions for HIP 6407, HIP 54582, HIP 62039 and HIP 30037, of which the latter is orbited by a 0.06 M⊙ brown dwarf in a 1 m long orbit. We report the orbital parameters of the systems with well-sampled orbits and, in addition, the lower limits of parameters for the companions that only display a curvature in their radial velocities. For the linear trend binaries, we report an estimate of the masses of their companions when their observed separation is available, and a minimum mass otherwise. We conclude that solar twin binaries with low-mass stellar companions at moderate orbital periods do not display signs of a distinct rotational evolution when compared to single stars. We confirm that the three peculiar stars are double-lined binaries, and that their companions are polluting their spectra, which explains the observed anomalies.

Discovery of a Highly Unequal-mass Binary T Dwarf with Keck Laser Guide Star Adaptive Optics: A Coevality Test of Substellar Theoretical Models and Effective Temperatures

NASA Astrophysics Data System (ADS)

Liu, Michael C.; Dupuy, Trent J.; Leggett, S. K.

2010-10-01

Highly unequal-mass ratio binaries are rare among field brown dwarfs, with the mass ratio distribution of the known census described by q (4.9±0.7). However, such systems enable a unique test of the joint accuracy of evolutionary and atmospheric models, under the constraint of coevality for the individual components (the "isochrone test"). We carry out this test using two of the most extreme field substellar binaries currently known, the T1 + T6 epsilon Ind Bab binary and a newly discovered 0farcs14 T2.0 + T7.5 binary, 2MASS J12095613-1004008AB, identified with Keck laser guide star adaptive optics. The latter is the most extreme tight binary resolved to date (q ≈ 0.5). Based on the locations of the binary components on the Hertzsprung-Russell (H-R) diagram, current models successfully indicate that these two systems are coeval, with internal age differences of log(age) = -0.8 ± 1.3(-1.0+1.2 -1.3) dex and 0.5+0.4 -0.3(0.3+0.3 -0.4) dex for 2MASS J1209-1004AB and epsilon Ind Bab, respectively, as inferred from the Lyon (Tucson) models. However, the total mass of epsilon Ind Bab derived from the H-R diagram (≈ 80 M Jup using the Lyon models) is strongly discrepant with the reported dynamical mass. This problem, which is independent of the assumed age of the epsilon Ind Bab system, can be explained by a ≈ 50-100 K systematic error in the model atmosphere fitting, indicating slightly warmer temperatures for both components; bringing the mass determinations from the H-R diagram and the visual orbit into consistency leads to an inferred age of ≈ 6 Gyr for epsilon Ind Bab, older than previously assumed. Overall, the two T dwarf binaries studied here, along with recent results from T dwarfs in age and mass benchmark systems, yield evidence for small (≈100 K) errors in the evolutionary models and/or model atmospheres, but not significantly larger. Future parallax, resolved spectroscopy, and dynamical mass measurements for 2MASS J1209-1004AB will enable a more stringent application of the isochrone test. Finally, the binary nature of this object reduces its utility as the primary T3 near-IR spectral typing standard; we suggest SDSS J1206+2813 as a replacement. Most of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

STUDYING ATMOSPHERE-DOMINATED HOT JUPITER KEPLER PHASE CURVES: EVIDENCE THAT INHOMOGENEOUS ATMOSPHERIC REFLECTION IS COMMON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shporer, Avi; Hu, Renyu

2015-10-15

We identify three Kepler transiting planets, Kepler-7b, Kepler-12b, and Kepler-41b, whose orbital phase-folded light curves are dominated by planetary atmospheric processes including thermal emission and reflected light, while the impact of non-atmospheric (i.e., gravitational) processes, including beaming (Doppler boosting) and tidal ellipsoidal distortion, is negligible. Therefore, those systems allow a direct view of their atmospheres without being hampered by the approximations used in the inclusion of both atmospheric and non-atmospheric processes when modeling the phase-curve shape. We present here the analysis of Kepler-12b and Kepler-41b atmosphere based on their Kepler phase curve, while the analysis of Kepler-7b was already presentedmore » elsewhere. The model we used efficiently computes reflection and thermal emission contributions to the phase curve, including inhomogeneous atmospheric reflection due to longitudinally varying cloud coverage. We confirm Kepler-12b and Kepler-41b show a westward phase shift between the brightest region on the planetary surface and the substellar point, similar to Kepler-7b. We find that reflective clouds located on the west side of the substellar point can explain the phase shift. The existence of inhomogeneous atmospheric reflection in all three of our targets, selected due to their atmosphere-dominated Kepler phase curve, suggests this phenomenon is common. Therefore, it is also likely to be present in planetary phase curves that do not allow a direct view of the planetary atmosphere as they contain additional orbital processes. We discuss the implications of a bright-spot shift on the analysis of phase curves where both atmospheric and gravitational processes appear, including the mass discrepancy seen in some cases between the companion’s mass derived from the beaming and ellipsoidal photometric amplitudes. Finally, we discuss the potential detection of non-transiting but otherwise similar planets, whose mass is too small to show a gravitational photometric signal, but their atmosphere is reflective enough to show detectable phase modulations.« less

ALMA Measurements of Circumstellar Material in the GQ Lup System

NASA Astrophysics Data System (ADS)

MacGregor, Meredith A.; Wilner, David J.; Czekala, Ian; Andrews, Sean M.; Dai, Y. Sophia; Herczeg, Gregory J.; Kratter, Kaitlin M.; Kraus, Adam L.; Ricci, Luca; Testi, Leonardo

2017-01-01

We present Atacama Large Millimeter/submillimeter Array observations of the GQ Lup system, a young Sun-like star with a substellar-mass companion in a wide-separation orbit. These observations of 870 μm continuum and CO J = 3-2 line emission with beam size ˜0.″3 (˜45 au) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with an FWHM of 59 ± 12 au, while the gas has a larger extent with a characteristic radius of 46.5 ± 1.8 au. By forward-modeling the velocity field of the circumprimary disk based on the CO emission, we constrain the mass of GQ Lup A to be M* = (1.03 ± 0.05) ∗ (d/156 pc) M⊙, where d is a known distance, and determine that we view the disk at an inclination angle of 60.°5 ± 0.°5 and a position angle of 346° ± 1°. The 3σ upper limit on the 870 μm flux density of any circumplanetary disk associated with GQ Lup b of <0.15 mJy implies an upper limit on the dust disk mass of <0.04 M⊕ for standard assumptions about optically thin emission. We discuss proposed mechanisms for the formation of wide-separation substellar companions given the non-detection of circumplanetary disks around GQ Lup b and other similar systems.

An X-shooter survey of star forming regions: Low-mass stars and sub-stellar objects

NASA Astrophysics Data System (ADS)

Alcalá, J. M.; Stelzer, B.; Covino, E.; Cupani, G.; Natta, A.; Randich, S.; Rigliaco, E.; Spezzi, L.; Testi, L.; Bacciotti, F.; Bonito, R.; Covino, S.; Flaccomio, E.; Frasca, A.; Gandolfi, D.; Leone, F.; Micela, G.; Nisini, B.; Whelan, E.

2011-03-01

We present preliminary results of our X-shooter survey in star forming regions. In this contribution we focus on sub-samples of young stellar and sub-stellar objects (YSOs) in the Lupus star forming region and in the TW Hya association. We show that the X-shooter spectra are suitable for conducting several parallel studies such as YSO + disk fundamental parameters, accretion and outflow activity in the very low-mass (VLM) and sub-stellar regimes, as well as magnetic activity in young VLM YSOs, and Li abundance determinations. The capabilities of X-shooter in terms of wide spectral coverage, resolution and limiting magnitudes, allow us to assess simultaneously the accretion/outflow, magnetic activity, and disk diagnostics, from the UV and optical to the near-IR, avoiding ambiguities due to possible YSO variability. Based on observations collected at the European Southern Observatory, Chile, under Programmes 084.C-0269 and 085.C-0238.

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

PubMed Central

Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; de Wit, Julien; Burdanov, Artem; Van Grootel, Valérie; Burgasser, Adam; Triaud, Amaury H. M. J.; Opitom, Cyrielle; Demory, Brice-Olivier; Sahu, Devendra K.; Bardalez Gagliuffi, Daniella; Magain, Pierre; Queloz, Didier

2017-01-01

Stellar-like objects with effective temperatures of 2700K and below are referred to as “ultracool dwarfs”1. This heterogeneous group includes both extremely low-mass stars and brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15% of the stellar-like objects in the vicinity of the Sun2. Based on the small masses and sizes of their protoplanetary disks3,4, core-accretion theory for ultracool dwarfs predicts a large, but heretofore undetected population of close-in terrestrial planets5, ranging from metal-rich Mercury-sized planets6 to more hospitable volatile-rich Earth-sized planets7. Here we report the discovery of three short-period Earth-sized planets transiting an ultracool dwarf star 12 parsecs away using data collected by the TRAPPIST8 telescope as part of an ongoing prototype transit survey9. The inner two planets receive four and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star10. Eleven orbits remain possible for the third planet based on our data, the most likely resulting in an irradiation significantly smaller than Earth's. The infrared brightness of the host star combined with its Jupiter-like size offer the possibility of thoroughly characterizing the components of this nearby planetary system. PMID:27135924

New Evidence for a Substellar Luminosity Problem: Dynamical Mass for the Brown Dwarf Binary Gl 417BC

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.; Liu, Michael C.; Ireland, Michael J.

2014-08-01

We present new evidence for a problem with cooling rates predicted by substellar evolutionary models that implies that model-derived masses in the literature for brown dwarfs and directly imaged planets may be too high. Based on our dynamical mass for Gl 417BC (L4.5+L6) and a gyrochronology system age from its young, solar-type host star, commonly used models predict luminosities 0.2-0.4 dex lower than we observe. This corroborates a similar luminosity-age discrepancy identified in our previous work on the L4+L4 binary HD 130948BC, which coincidentally has nearly identical component masses (≈50-55 M Jup) and age (≈800 Myr) as Gl 417BC. Such a luminosity offset would cause systematic errors of 15%-25% in model-derived masses at this age. After comparing different models, including cloudless models that should not be appropriate for mid-L dwarfs like Gl 417BC and HD 130948BC but actually match their luminosities better, we speculate the observed overluminosity could be caused by opacity holes (i.e., patchy clouds) in these objects. Moreover, from hybrid substellar evolutionary models that account for cloud disappearance, we infer the corresponding phase of overluminosity may extend from a few hundred million years up to a few gigayears and cause masses to be overestimated by up to 25%, even well after clouds disappear from view entirely. Thus, the range of ages and spectral types affected by this potential systematic shift in luminosity evolution would encompass most known directly imaged gas-giants and field brown dwarfs. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Multi-wavelength Observations of Accreting Compact Objects

NASA Astrophysics Data System (ADS)

Hernandez Santisteban, Juan Venancio

2016-11-01

The study of compact binaries invokes core astrophysical concepts ranging from stellar and sub-stellar atmospheres and interiors, stellar and binary evolution to physics of accretion. All of these systems are hosts to a compact object a white dwarf, neutron star or black hole ???? which produces a wide variety of exotic and energetic phenomena across the full electromagnetic spectrum. In this thesis, I will make use of multi-wavelength observations ranging from far-ultraviolet to nearinfrared in order to investigate two main topics: a) the late evolution of cataclysmic variables, and b) the accreting state of transitional millisecond pulsars. Firstly, I analyse the Very Large Telescope X-Shooter time-resolved spectroscopy of the short orbital period cataclysmic variable, SDSS J1433+1011, in Chapter 2. The wide wavelength coverage allowed me to perform a detailed characterisation of the system, as well as a direct mass measurement of the brown dwarf companion. I show that the donor in SDSS J1433+1011 successfully transitioned from the stellar to sub-stellar regime, as predicted by evolutionary models. Further light-curve modelling allowed me to show that a low albedo as well as a low heat circulation efficiency is present in the atmosphere of the sub-stellar donor. In Chapter 3, I analyse data from large synoptic surveys, such as SDSS and PTF, to search for the predicted population of dead cataclysmic variables. Following the non-detection of dead CVs, I was able to estimate the space density (?0 < 2?10????5 pc????3) of this hidden population via a Monte Carlo simulation of the Galactic CV population. In Chapter 4, I present Hubble Space Telescope ultraviolet observations of the transitional millisecond pulsar PSR J1023+0038, during its latest accretion state. In combination with optical and near-infrared data, I show that a standard accretion disc does not reach the magnetosphere of the neutron star. Instead, the overall spectrum is consistent with a truncated disc at ? 2:3 ? 109 cm away from the compact object. Furthermore, the ultraviolet data shares remarkable similarities with the only accreting white dwarf in a propeller regime, AE Aqr. Finally, I summarise my results in Chapter 5 and provide future lines of research in accreting compact binaries based on this work.

Substellar objects in nearby young clusters (SONYC). VIII. Substellar population in Lupus 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mužić, Koraljka; Scholz, Alexander; Geers, Vincent C.

2014-04-20

SONYC—Substellar Objects in Nearby Young Clusters—is a survey program to investigate the frequency and properties of substellar objects in nearby star-forming regions. We present a new imaging and spectroscopic survey conducted in the young (∼1 Myr), nearby (∼200 pc) star-forming region Lupus 3. Deep optical and near-infrared images were obtained with MOSAIC-II and NEWFIRM at the CTIO 4 m telescope, covering ∼1.4 deg{sup 2} on the sky. The i-band completeness limit of 20.3 mag is equivalent to 0.009-0.02 M {sub ☉}, for A{sub V} ≤ 5. Photometry and 11-12 yr baseline proper motions were used to select candidate low-mass membersmore » of Lupus 3. We performed a spectroscopic follow-up of 123 candidates, using VIMOS at the Very Large Telescope, and we identify 7 probable members, among which 4 have spectral type later than M6.0 and T {sub eff} ≤ 3000 K, i.e., are probably substellar in nature. Two of the new probable members of Lupus 3 appear underluminous for their spectral class and exhibit emission line spectrum with strong H{sub α} or forbidden lines associated with active accretion. We derive a relation between the spectral type and effective temperature: T {sub eff} = (4120 ± 175) – (172 ± 26) × SpT, where SpT refers to the M spectral subtype between 1 and 9. Combining our results with the previous works on Lupus 3, we show that the spectral type distribution is consistent with that in other star-forming regions, as well as the derived star-to-brown dwarf ratio of 2.0-3.3. We compile a census of all spectroscopically confirmed low-mass members with spectral type M0 or later.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yun; Kouwenhoven, M. B. N.; Stamatellos, D.

The origin of very low-mass hydrogen-burning stars, brown dwarfs (BDs), and planetary-mass objects (PMOs) at the low-mass end of the initial mass function is not yet fully understood. Gravitational fragmentation of circumstellar disks provides a possible mechanism for the formation of such low-mass objects. The kinematic and binary properties of very low-mass objects formed through disk fragmentation at early times (<10 Myr) were discussed in our previous paper. In this paper we extend the analysis by following the long-term evolution of disk-fragmented systems up to an age of 10 Gyr, covering the ages of the stellar and substellar populations inmore » the Galactic field. We find that the systems continue to decay, although the rates at which companions escape or collide with each other are substantially lower than during the first 10 Myr, and that dynamical evolution is limited beyond 1 Gyr. By t = 10 Gyr, about one third of the host stars are single, and more than half have only one companion left. Most of the other systems have two companions left that orbit their host star in widely separated orbits. A small fraction of companions have formed binaries that orbit the host star in a hierarchical triple configuration. The majority of such double-companion systems have internal orbits that are retrograde with respect to their orbits around their host stars. Our simulations allow a comparison between the predicted outcomes of disk fragmentation with the observed low-mass hydrogen-burning stars, BDs, and PMOs in the solar neighborhood. Imaging and radial velocity surveys for faint binary companions among nearby stars are necessary for verification or rejection of the formation mechanism proposed in this paper.« less

A HST/WFC3 Search for Substellar Companions in the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Strampelli, Giovanni Maria; Aguilar, Jonathan; Aparicio, Antonio; Piotto, Giampaolo; Pueyo, Laurent; Robberto, Massimo

2018-01-01

We present new results relative to the population of substellar binaries in the Orion Nebula Cluster. We reprocessed HST/WFC3 data using an analysis technique developed to detect close companions in the wings of the stellar PSFs, based on the PyKLIP implementation of the KLIP PSF subtraction algorithm. Starting from a sample of ~1200 stars selected over the range J=11-15 mag, we were able to uncover ~80 candidate companions in the magnitude range J=16-23 mag. We use the presence of the 1.4 micron H2O absorption feature in the companion photosphere to discriminate 32 bona-fide substellar candidates from a population of reddened background objects. We derive an estimate of the companion mass assuming a 2Myr isochrone and the reddening of their primary. With 8 stellar companions, 19 brown dwarfs and 5 planetary mass objects, our study provide us with an unbiased sample of companions at the low-mass end of the IMF, probing the transition from binary to planetary systems.

The carbonate-silicate cycle and CO2/climate feedbacks on tidally locked terrestrial planets.

PubMed

Edson, Adam R; Kasting, James F; Pollard, David; Lee, Sukyoung; Bannon, Peter R

2012-06-01

Atmospheric gaseous constituents play an important role in determining the surface temperatures and habitability of a planet. Using a global climate model and a parameterization of the carbonate-silicate cycle, we explored the effect of the location of the substellar point on the atmospheric CO(2) concentration and temperatures of a tidally locked terrestrial planet, using the present Earth continental distribution as an example. We found that the substellar point's location relative to the continents is an important factor in determining weathering and the equilibrium atmospheric CO(2) level. Placing the substellar point over the Atlantic Ocean results in an atmospheric CO(2) concentration of 7 ppmv and a global mean surface air temperature of 247 K, making ∼30% of the planet's surface habitable, whereas placing it over the Pacific Ocean results in a CO(2) concentration of 60,311 ppmv and a global temperature of 282 K, making ∼55% of the surface habitable.

A Test of Pre-Main-Sequence Evolutionary Models across the Stellar/Substellar Boundary Based on Spectra of the Young Quadruple GG Tauri

NASA Astrophysics Data System (ADS)

White, Russel J.; Ghez, A. M.; Reid, I. Neill; Schultz, Greg

1999-08-01

We present spatially separated optical spectra of the components of the young hierarchical quadruple GG Tau. Spectra of GG Tau Aa and Ab (separation 0.25"~35 AU) were obtained with the Faint Object Spectrograph on board the Hubble Space Telescope. Spectra of GG Tau Ba and Bb (separation 1.48"~207 AU) were obtained with both the HIRES and the LRIS spectrographs on the W. M. Keck telescopes. The components of this minicluster, which span a wide range in spectral type (K7-M7), are used to test both evolutionary models and the temperature scale for very young, low-mass stars under the assumption of coeval formation. Of the evolutionary models tested, those of Baraffe et al. yield the most consistent ages when combined with a temperature scale intermediate between that of dwarfs and giants. The version of the Baraffe et al. models computed with a mixing length nearly twice the pressure scale height is of particular interest, as it predicts masses for GG Tau Aa and Ab that are in agreement with their dynamical mass estimate. Using this evolutionary model and a coeval (at 1.5 Myr) temperature scale, we find that the coldest component of the GG Tau system, GG Tau Bb, is substellar with a mass of 0.044+/-0.006 Msolar. This brown dwarf companion is especially intriguing as it shows signatures of accretion, although this accretion is not likely to alter its mass significantly. GG Tau Bb is currently the lowest mass, spectroscopically confirmed companion to a T Tauri star, and is one of the coldest, lowest mass T Tauri objects in the Taurus-Auriga star-forming region. Based partly on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

The Orion Nebula Cluster as a Paradigm of Star Formation

NASA Astrophysics Data System (ADS)

Robberto, Massimo

2014-10-01

We propose a 52-orbit Treasury Program to investigate two fundamental questions of star formation: a) the low-mass tail of the IMF, down to a few Jupiter masses; b) the dynamical evolution of clusters, as revealed by stellar proper motions. We target the Orion Nebula Cluster (ONC) using WFC3 and ACS in coordinated parallel mode to perform a synoptic survey in the 1.345micron H2O feature and Ic broad-band. Our main objectives are: 1) to discover and classify ~500 brown dwarfs and planetary-mass objects in the field, extending the IMF down to lowest masses formed by gravitational collapse. Using the latest generation of high contrast image processing we will also search for faint companions, reaching down to sub-arcsecond separations and 1E-4 flux ratios. 2) to derive high precision (~0.2km/s) relative proper motions of low-mass stars and substellar objects (about 1000 sources total), leveraging on first epoch data obtained by our previous HST Treasury Program about 10 years ago. These data will unveil the cluster dynamics: velocity dispersion vs. mass, substructures, and the fraction of escaping sources. Only HST can access the IR H2O absorption feature sensitive to the effective temperature of substellar objects, while providing the exceptionally stable PSF needed for the detection of faint companions, and the identical ACS platform for our second epoch proper-motion survey. This program will provide the definitive HST legacy dataset on the ONC. Our High-Level Science Products will be mined by the community, both statistically to constrain competing theories of star formation, and to study in depth the multitude of exotic sources harboured by the cluster.

Line Bisector Variations in Stars with Extrasolar Planets

NASA Astrophysics Data System (ADS)

Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman, T.

1999-12-01

We present the results from a high-resolution, synoptic spectroscopic program of observation of ten F- and G-type stars, seven of which exhibit periodic radial velocity variations attributed to the presence of one or more substellar companions. The observations were obtained from 1998 March to 1999 February using the 1.52-m NSO McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction with the solar-stellar spectrograph. The spectra were acquired with a resolving power of approximately 1.2 x 105. The line bisector was then derived from unblended photospheric features. In particular, we define the velocity displacement of the spectral line bisector and determine the bisector amplitude for the Fe I absorption line at 625.26 nm in order to search for variations in the line asymmetry over time. Such variations could mimic Doppler shifts in observations with lower spectral resolution. Examination of the bisector velocity displacement over the time span of our observations reveals no substantial difference between stars with planetary companions and those without reported companions. We find no correlation between the bisector variations and the orbital phase of a substellar companion in any of our target stars. Simulations of a periodic signal with noise levels based on our measurement errors suggest that we can exclude bisector variations with amplitudes greater than about 20 m s-1. These results support the conclusion that extrasolar planets best explain the observed periodic variations in radial velocity. This work was supported by a NASA grant to the NOAO under the auspices of the Origins of Solar Systems Program. MP gratefully acknowledges support from the NSF-sponsored Research Experience for Undergraduates (REU) program at the NOAO. The NOAO is operated by AURA, Inc., under a cooperative agreement with the NSF.

A possible brown dwarf companion to Gliese 569

NASA Technical Reports Server (NTRS)

Forrest, W. J.; Shure, Mark; Skrutskie, M. F.

1988-01-01

A faint cool companion to Gliese 569, discovered during an IR imaging survey of nearby stars, may be the lowest-mass stellar object yet found. The companion is somewhat cooler in its 1.65-3.75-micron energy distribution than the coolest known main-sequence stars, indicating a low mass. Despite its lower temperature, it is more luminous than similar extremely low-mass stars, suggesting that it is either a young low-mass star evolving toward the main sequence or a cooling substellar brown dwarf. The primary star has emission lines and a low space velocity and exhibits flaring, all of which imply youth for this system. Observations of Gliese 569 and its companion over a period of 2 yr confirm the common proper motion expected of a true binary. The 5-arcsec apparent separation (50 AU) implies an orbital period of roughly 500 yr, which will permit an eventual direct determination of the mass of the companion.

A Palette of Climates for Gliese 581g

NASA Astrophysics Data System (ADS)

Pierrehumbert, R. T.

2011-01-01

We consider a range of possible climates for the habitable-zone planet candidate, Gliese 581g, contingent on a plausible set of hypothetical atmospheres and assuming the planet to be tide locked. The two most habitable states we find are (1) a nearly airless Super-Europa with thin ice at the substellar point and (2) an "Eyeball Earth" which is mostly frozen but supports a substantial stable pool of open water centered on the substellar point. We discuss the prospects for observational determination of what kind of climate 581g actually supports.

Filaments in Lupus I

NASA Astrophysics Data System (ADS)

Takahashi, Satoko; Rodon, J.; De Gregorio-Monsalvo, I.; Plunkett, A.

2017-06-01

The mechanisms behind the formation of sub-stellar mass sources are key to determine the populations at the low-mass end of the stellar distribution. Here, we present mapping observations toward the Lupus I cloud in C18O(2-1) and 13CO(2-1) obtained with APEX. We have identified a few velocity-coherent filaments. Each contains several substellar mass sources that are also identified in the 1.1mm continuum data (see also SOLA catalogue presentation). We will discuss the velocity structure, fragmentation properties of the identified filaments, and the nature of the detected sources.

A PALETTE OF CLIMATES FOR GLIESE 581g

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierrehumbert, R. T., E-mail: rtp1@geosci.uchicago.edu

2011-01-01

We consider a range of possible climates for the habitable-zone planet candidate, Gliese 581g, contingent on a plausible set of hypothetical atmospheres and assuming the planet to be tide locked. The two most habitable states we find are (1) a nearly airless Super-Europa with thin ice at the substellar point and (2) an 'Eyeball Earth' which is mostly frozen but supports a substantial stable pool of open water centered on the substellar point. We discuss the prospects for observational determination of what kind of climate 581g actually supports.

CHANGING PHASES OF ALIEN WORLDS: PROBING ATMOSPHERES OF KEPLER PLANETS WITH HIGH-PRECISION PHOTOMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esteves, Lisa J.; Mooij, Ernst J. W. De; Jayawardhana, Ray, E-mail: esteves@astro.utoronto.ca, E-mail: demooij@astro.utoronto.ca, E-mail: rayjay@yorku.ca

We present a comprehensive analysis of planetary phase variations, including possible planetary light offsets, using eighteen quarters of data from the Kepler space telescope. Our analysis found fourteen systems with significant detections in each of the phase curve components: planet’s phase function, secondary eclipse, Doppler boosting, and ellipsoidal variations. We model the full phase curve simultaneously, including primary and secondary transits, and derive albedos, day- and night-side temperatures and planet masses. Most planets manifest low optical geometric albedos (< 0.25), with the exception of Kepler-10b, Kepler-91b, and KOI-13b. We find that KOI-13b, with a small eccentricity of 0.0006 ± 0.0001,more » is the only planet for which an eccentric orbit is favored. We detect a third harmonic for HAT-P-7b for the first time, and confirm the third harmonic for KOI-13b reported in Esteves et al.: both could be due to their spin–orbit misalignments. For six planets, we report a planetary brightness peak offset from the substellar point: of those, the hottest two (Kepler-76b and HAT-P-7b) exhibit pre-eclipse shifts or on the evening-side, while the cooler four (Kepler-7b, Kepler-8b, Kepler-12b, and Kepler-41b) peak post-eclipse or on the morning-side. Our findings dramatically increase the number of Kepler planets with detected planetary light offsets, and provide the first evidence in the Kepler data for a correlation between the peak offset direction and the planet’s temperature. Such a correlation could arise if thermal emission dominates light from hotter planets that harbor hot spots shifted toward the evening-side, as theoretically predicted, while reflected light dominates cooler planets with clouds on the planet’s morning-side.« less

Update on ONC's Substellar IMF: A Second Peak in the Brown Dwarf Regime

NASA Astrophysics Data System (ADS)

Drass, Holger; Bayo, A.; Chini, R.; Haas, M.

2017-06-01

The Orion Nebular Cluster (ONC) has become the prototype cluster for studying the Initial Mass Function (IMF). In a deep JHK survey of the ONC with HAWK-I we detected a large population of 900 Brown Dwarfs and Planetary Mass Object candidates presenting a pronounced second peak in the substellar IMF. One of the most obvious issues of this result is the verification of cluster membership. The analysis so far was mainly based on statistical consideration. In this presentation I will show the results from using different high-resolution extinction map to determine the ONC membership.

Confirmation and characterization of young planetary companions hidden in the HST NICMOS archive

NASA Astrophysics Data System (ADS)

Pueyo, Laurent

2013-10-01

We propose to conduct WFC3 high contrast observations of six faint planetary candidates orbiting young {1 to 100 Myrs} stars identified in archival HST NICMOS coronagraphic data as part of our team's program AR-12652. Such rare objects are of the utmost importance to comparative exo-planetology as their physical properties reflect the initial conditions of still poorly constrained planetary formation mechanisms. Moreover directly imaged systems are precious artifacts in the expanding exo-planetary treasure trove as they are readily available for spectroscopic characterization. Our statistical analysis, which combines population synthesis models and empirical inspections of the entire NICMOS field of view for all sources observed in coronaraphic mode, almost guarantees that one of these six faint candidates is associated with its putative host star. We will conduct our observation in four near infrared filter, F125W, F160W to establish the baseline luminosity of our candidates and in F127M and F139M in order to probe the depth their water absorption features, characteristic of substellar /exo-planetary like atmospheres. Because of the youth of our targets, this program, which only requires a modest 12 HST orbits, will almost certainly identify and image a young or adolescent exo-planet.

Towards high accuracy tests on the substellar IMF in young clusters. A survey in NGC 2024.

NASA Astrophysics Data System (ADS)

Da Rio, Nicola

2017-08-01

Measuring the Initial Mass Function in young clusters, and testing its universality, is a fundamental benchmark to constrain the physical processes and theoretical models of star formation. The shape and universality of the stellar IMF are well known. Our observational characterization of the substellar IMF, on the other hand, remains more uncertain, along with its possible environmental variations. Because of this, the physical processes that play a role in the formation of brown dwarfs are not fully constrained. In Cycle 22 we were awarded HST time to carry out the deepest spectro-photometric census of BDs in a young cluster: the Orion Nebula Cluster. Through deep WFC3/IR narrow band imaging, we are able to obtain Teff and A_V down to 15Mjup. Preliminary analysis limited to a portion of the total field of view allows us to classify several hundreds BDs, place them in the HRD and obtain, for an extinction limited sample, the complete and consistent IMF down to planetary masses. The substellar slope is consistent with the Galactic IMF but a rapid drop is found at the H-burning limit. We propose to carry out a nearly identical survey with HST in a younger, less massive nearby cluster: NGC2024 in the Flame Nebula. This will allow us to derive the complete census of the young population down to planetary masses, derive the IMF, enabling a consistent comparison with the results in the ONC. We will specifically look for statistically significant IMF variations with environmental properties (cluster mass, density) and investigate primordial mass segregation in the substellar regime. These results will significantly help to constrain the mechanisms involved in BD formation.

A companion on the planet/brown dwarf mass boundary on a wide orbit discovered by gravitational microlensing

NASA Astrophysics Data System (ADS)

Poleski, R.; Udalski, A.; Bond, I. A.; Beaulieu, J. P.; Clanton, C.; Gaudi, S.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, Szymon; Skowron, J.; Wyrzykowski, Ł.; Ulaczyk, K.; Bennett, D. P.; Sumi, T.; Suzuki, D.; Rattenbury, N. J.; Koshimoto, N.; Abe, F.; Asakura, Y.; Barry, R. K.; Bhattacharya, A.; Donachie, M.; Evans, P.; Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Ranc, C.; Saito, To.; Sharan, A.; Sullivan, D. J.; Tristram, P. J.; Yamada, T.; Yamada, T.; Yonehara, A.; Batista, V.; Marquette, J. B.

2017-08-01

We present the discovery of a substellar companion to the primary host lens in the microlensing event MOA-2012-BLG-006. The companion-to-host mass ratio is 0.016, corresponding to a companion mass of ≈8 MJup(M∗/ 0.5 M⊙). Thus, the companion is either a high-mass giant planet or a low-mass brown dwarf, depending on the mass of the primary M∗. The companion signal was separated from the peak of the primary event by a time that was as much as four times longer than the event timescale. We therefore infer a relatively large projected separation of the companion from its host of ≈10 au(M∗/ 0.5 M⊙)1 / 2 for a wide range (3-7 kpc) of host star distances from the Earth. We also challenge a previous claim of a planetary companion to the lens star in microlensing event OGLE-2002-BLG-045.

The Optical Gravitational Lensing Experiment. Additional Planetary and Low-Luminosity Object Transits from the OGLE 2001 and 2002 Observational Campaigns

NASA Astrophysics Data System (ADS)

Udalski, A.; Pietrzynski, G.; Szymanski, M.; Kubiak, M.; Zebrun, K.; Soszynski, I.; Szewczyk, O.; Wyrzykowski, L.

2003-06-01

The photometric data collected by OGLE-III during the 2001 and 2002 observational campaigns aiming at detection of planetary or low-luminosity object transits were corrected for small scale systematic effects using the data pipeline by Kruszewski and Semeniuk and searched again for low amplitude transits. Sixteen new objects with small transiting companions, additional to previously found samples, were discovered. Most of them are small amplitude cases which remained undetected in the original data. Several new objects seem to be very promising candidates for systems containing substellar objects: extrasolar planets or brown dwarfs. Those include OGLE-TR-122, OGLE-TR-125, OGLE-TR-130, OGLE-TR-131 and a few others. Those objects are particularly worth spectroscopic follow-up observations for radial velocity measurements and mass determination. With well known photometric orbit only a few RV measurements should allow to confirm their actual status. All photometric data of presented objects are available to the astronomical community from the OGLE Internet archive.

New binaries among UV-selected, hot subdwarf stars and population properties

NASA Astrophysics Data System (ADS)

Kawka, A.; Vennes, S.; O'Toole, S.; Németh, P.; Burton, D.; Kotze, E.; Buckley, D. A. H.

2015-07-01

We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ˜0.17 to 3 d. One new system, GALEX J2205-3141, shows reflection on an M dwarf companion. Three other objects show significant short-period variations, but their orbital parameters could not be constrained. Two systems comprising a hot subdwarf paired with a bright main-sequence/giant companion display short-period photometric variations possibly due to irradiation or stellar activity and are also short-period candidates. All except two candidates were drawn from a selection of subluminous stars in the Galaxy Evolution Explorer ultraviolet sky survey. Our new identifications also include a low-mass subdwarf B star and likely progenitor of a low-mass white dwarf (GALEX J0805-1058) paired with an unseen, possibly substellar, companion. The mass functions of the newly identified binaries imply minimum secondary masses ranging from 0.03 to 0.39 M⊙. Photometric time series suggest that, apart from GALEX J0805-1058 and J2205-3141, the companions are most likely white dwarfs. We update the binary population statistics: close to 40 per cent of hot subdwarfs have a companion. Also, we found that the secondary mass distribution shows a low-mass peak attributed to late-type dwarfs, and a higher mass peak and tail distribution attributed to white dwarfs and a few spectroscopic composites. Also, we found that the population kinematics imply an old age and include a few likely halo population members.

On Mapping Exoplanet Atmospheres with High-dispersion Spectro-polarimetry: Some Model Predictions

NASA Astrophysics Data System (ADS)

García Muñoz, A.

2018-02-01

Planets reflect and linearly polarize the radiation that they receive from their host stars. The emergent polarization is sensitive to aspects of the planet’s atmosphere such as the gas composition and the occurrence of condensates and their optical properties. Extracting this information will represent a major step in the characterization of exoplanets. The numerical simulations presented here show that the polarization of a spatially unresolved exoplanet may be detected by cross-correlating high-dispersion linear polarization and intensity (brightness) spectra of the planet–star system. The Doppler shift of the planet-reflected starlight facilitates the separation of this signal from the polarization introduced by the interstellar medium and the terrestrial atmosphere. The selection of the orbital phases and wavelengths at which to study the planet is critical. An optimal choice, however, will partly depend on information about the atmosphere that is a priori unknown. We elaborate on the cases of close-in giant exoplanets with non-uniform cloud coverage, an outcome of recent surveys of brightness phase curves from space, and for which the hemispheres east and west of the substellar point will produce different polarizations. With integration times of the order of hours at a 10 m telescope, the technique might distinguish among some proposed asymmetric cloud scenarios with fractional polarizations of 10 parts per million for one such planet orbiting a V-mag = 5.5 host star. Future 30–40 m telescopes equipped with high-dispersion spectro-polarimeters will be able to investigate the linear polarization of smaller planets orbiting fainter stars and look for molecular features in their polarization spectra.

Knowing Our Neighbors: Fundamental Properties of Nearby Stars

NASA Astrophysics Data System (ADS)

Bartlett, Jennifer L.; Ianna, P. A.; Henry, T. J.; Begam, M. C.; Jao, W.; Subasavage, J. P., Jr.; Nearby Stars, Research Consortium on

2007-12-01

Although the stars within 25 pc of the Sun constitute the one stellar sample that we can aspire to know thoroughly, we continue identifying objects closer than 10 pc. We know even less about local substellar populations, especially planets. The Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI) is observing 31 late-type, red dwarfs selected for my thesis as part of a larger effort to complete the nearby star census. Preliminary parallaxes substantiate distances less than 25 pc for at least 28 stars. Of these, LP 991-84, LHS 6167, and LP 876-10 may lie within 10 pc. Preliminary proper motions for all but three stars exceed 0.2” yr-1. One recently established neighbor, LP 869-26, also appears to be a new binary. Associated VRI photometry and spectroscopy are in progress as well. Many of these stars are potential targets for astrometric planet searches, such as the Space Interferometry Mission (SIM). In addition to confirming solar neighborhood membership, astrometry can discover brown dwarfs and planets. Time-series analyses of residuals to the UVa Southern Parallax Program (SPP) observations are contributing to frequency and distribution data for nearby substellar objects. In particular, LHS 288 displays an intriguing signal, which might be caused by a very low-mass companion. Twelve other SPP stars demonstrate no significant perturbations. Finally, re-analyzing the Leander McCormick Observatory photographic plates of Barnard's Star failed to detect any planets orbiting it. This study of more than 900 exposures was sensitive to bodies of 2.2 Jupiter masses or more. NSF grants AST 98-20711 and 05-07711, GSU, NASA-SIM, Litton Marine Systems, UVa, Hampden-Sydney College, US Naval Observatory, and the Levinson Fund of the Peninsula Community Foundation supported this research. The ANU Research School of Astronomy & Astrophysics allocated observing time generously. CTIOPI was an NOAO Survey Program and continues as part of the SMARTS Consortium.

A hot Saturn on an eccentric orbit around the giant star K2-132

NASA Astrophysics Data System (ADS)

Jones, M. I.; Brahm, R.; Espinoza, N.; Jordán, A.; Rojas, F.; Rabus, M.; Drass, H.; Zapata, A.; Soto, M. G.; Jenkins, J. S.; Vučković, M.; Ciceri, S.; Sarkis, P.

2018-06-01

Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P ≲ 10 days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017, AJ, 154, 254). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff = 4878 ± 70 K, log g = 3.289 ± 0.004, and [Fe/H] = -0.11 ± 0.05 dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P = 9.1708 ± 0.0025 d, e = 0.290 ± 0.049, Mp = 0.495 ± 0.007 MJ and Rp = 1.089 ± 0.006 RJ. This is the fifth known planet orbiting any giant star with a < 0.1, and the most eccentric one among them, making K2-132 b a very interesting object. Tables of the photometry and of the radial velocities are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/613/A76

DECam Survey for Substellar and Low-mass Stellar Members of Sco-Cen

NASA Astrophysics Data System (ADS)

Mamajek, Eric E.; Moolekamp, Fred; James, David; Luhman, Kevin; Pecaut, Mark; Metchev, Stanimir A.; Denbo, Sara; Bell, Cameron P. M.

2017-01-01

We present the results of a DECam imaging survey for low-mass stellar and substellar objects in the nearby Sco-Cen OB association. The DECam survey was taken in izY bands in 2013 and 2015 and covered $\\sim$87 deg$^2$ in the two nearest and oldest subgroups, Upper Cen-Lup ($\\sim$142 pc) and Lower Cen-Cru ($\\sim$118 pc; both with mean ages $\\sim$16 Myr). Using color-magnitude and proper motion selection, we identify 391 candidate Sco-Cen members with masses ranging from near the D-burning limit of $\\sim$13 M$_{Jup}$, through the H-burning limit, up to $\\sim$0.4 M$_\\odot$. Our initial spectroscopic follow-up with the ARCoIRIS and COSMOS spectrographs for 19 objects have yielded young M dwarfs showing signatures of low surface-gravity. Our survey yields the first constraints on the substellar and low-mass initial mass function and disk fraction in the two oldest Sco-Cen subgroups, and will yield a large sample of young, low-surface gravity M and L-type objects of constrained age, distance, and chemical composition. We acknowledge support from NSF award AST-1313029 and the REU Site in Physics and Astrophysics at the University of Rochester supported by NSF award PHY-1156339.

Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars

NASA Astrophysics Data System (ADS)

Jones, M. I.; Jenkins, J. S.; Brahm, R.; Wittenmyer, R. A.; Olivares E., F.; Melo, C. H. F.; Rojo, P.; Jordán, A.; Drass, H.; Butler, R. P.; Wang, L.

2016-05-01

Context. Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets. In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. Aims: During the past six years we have conducted a radial velocity follow-up program of 166 giant stars to detect substellar companions and to characterize their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. Methods: We took multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we computed precision radial velocities and derived atmospheric and physical parameters. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we detected the presence of several substellar companions. Results: We present four new planetary systems around the giant stars HIP 8541, HIP 74890, HIP 84056, and HIP 95124. Additionally, we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7+15.5-5.9% around stars with [Fe/H] ~ 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆ ~ 1.0 and 2.1 M⊙, with a maximum of f = 13.0+10.1-4.2% at M⋆ = 2.1 M⊙. Conclusions: We conclude that giant planets are preferentially formed around metal-rich stars. In addition, we conclude that they are more efficiently formed around more massive stars, in the stellar mass range of ~1.0-2.1 M⊙. These observational results confirm previous findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model. Based on observations collected at La Silla - Paranal Observatory under programs IDs 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345 and through the Chilean Telescope Time under programs IDs CN 12A-073, CN 12B-047, CN 13A-111, CN 13B-51, CN 14A-52, CN-15A-48, and CN-15B-25.

HABEBEE: habitability of eyeball-exo-Earths.

PubMed

Angerhausen, Daniel; Sapers, Haley; Citron, Robert; Bergantini, Alexandre; Lutz, Stefanie; Queiroz, Luciano Lopes; da Rosa Alexandre, Marcelo; Araujo, Ana Carolina Vieira

2013-03-01

Extrasolar Earth and super-Earth planets orbiting within the habitable zone of M dwarf host stars may play a significant role in the discovery of habitable environments beyond Earth. Spectroscopic characterization of these exoplanets with respect to habitability requires the determination of habitability parameters with respect to remote sensing. The habitable zone of dwarf stars is located in close proximity to the host star, such that exoplanets orbiting within this zone will likely be tidally locked. On terrestrial planets with an icy shell, this may produce a liquid water ocean at the substellar point, one particular "Eyeball Earth" state. In this research proposal, HABEBEE: exploring the HABitability of Eyeball-Exo-Earths, we define the parameters necessary to achieve a stable icy Eyeball Earth capable of supporting life. Astronomical and geochemical research will define parameters needed to simulate potentially habitable environments on an icy Eyeball Earth planet. Biological requirements will be based on detailed studies of microbial communities within Earth analog environments. Using the interdisciplinary results of both the physical and biological teams, we will set up a simulation chamber to expose a cold- and UV-tolerant microbial community to the theoretically derived Eyeball Earth climate states, simulating the composition, atmosphere, physical parameters, and stellar irradiation. Combining the results of both studies will enable us to derive observable parameters as well as target decision guidance and feasibility analysis for upcoming astronomical platforms.

Direct imaging and new technologies to search for substellar companions around MGs cool dwarfs

NASA Astrophysics Data System (ADS)

Gálvez-Ortiz, M. C.; Clarke, J. R. A.; Pinfield, D. J.; Folkes, S. L.; Jenkins, J. S.; García Pérez, A. E.; Burningham, B.; Day-Jones, A. C.; Jones, H. R. A.

2011-07-01

We describe here our project based in a search for sub-stellar companions (brown dwarfs and exo-planets) around young ultra-cool dwarfs (UCDs) and characterise their properties. We will use current and future technology (high contrast imaging, high-precision Doppler determinations) from the ground and space (VLT, ELT and JWST), to find companions to young objects. Members of young moving groups (MGs) have clear advantages in this field. We compiled a catalogue of young UCD objects and studied their membership to five known young moving groups: Local Association (Pleiades moving group, 20-150 Myr), Ursa Mayor group (Sirius supercluster, 300 Myr), Hyades supercluster (600 Myr), IC 2391 supercluster (35 Myr) and Castor moving group (200 Myr). To assess them as members we used different kinematic and spectroscopic criteria.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan

2013-05-15

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R {approx}< 30, 000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin i {approx} 50 M{sub Jup}) to a solar-type primary. At least three properties of this system allow it to masquerade as a singlemore » star with a very-low-mass companion: its large eccentricity (e {approx} 0.8), its relatively long period (P {approx} 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega} {approx} 189 Degree-Sign ). As a result of these properties, for {approx}95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e {approx} 0.3). Only during the {approx}5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of {approx}15 km s{sup -1} reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.« less

DISCOVERY OF A LOW-MASS COMPANION AROUND HR 3549

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mawet, D.; David, T.; Bottom, M.

2015-10-01

We report the discovery of a low-mass companion to HR 3549, an A0V star surrounded by a debris disk with a warm excess detected by WISE at 22 μm (10σ significance). We imaged HR 3549 B in the L band with NAOS-CONICA, the adaptive optics infrared camera of the Very Large Telescope, in January 2013 and confirmed its common proper motion in 2015 January. The companion is at a projected separation of ≃80 AU and position angle of ≃157°, so it is orbiting well beyond the warm disk inner edge of r > 10 AU. Our age estimate for thismore » system corresponds to a companion mass in the range 15–80 M{sub J}, spanning the brown dwarf regime, and so HR 3549 B is another recent addition to the growing list of brown dwarf desert objects with extreme mass ratios. The simultaneous presence of a warm disk and a brown dwarf around HR 3549 provides interesting empirical constraints on models of the formation of substellar companions.« less

SCExAO and GPI Y JH band photometry and integral field spectroscopy of the young brown dwarf companion to HD 1160

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Eugenio Victor; Currie, Thayne; Guyon, Olivier

Here, we present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957–1.120 μm) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5more » $${}_{-0.5}^{+1.0}$$, where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000–3100 K, a surface gravity of log g = 4–4.5, a radius of 1.55 ± 0.10 R J, and a luminosity of log L/L ⊙ = –2.76 ± 0.05. Neither the primary's Hertzspring–Russell diagram position nor atmospheric modeling of HD 1160 B show evidence for a subsolar metallicity. Interpretation of the HD 1160 B spectroscopy depends on which stellar system components are used to estimate the age. Considering HD 1160 A, B and C jointly, we derive an age of 80–125 Myr, implying that HD 1160 B straddles the hydrogen-burning limit (70–90 M J). If we consider HD 1160 A alone, younger ages (20–125 Myr) and a brown dwarf-like mass (35–90 M J) are possible. Interferometric measurements of the primary, a precise Gaia parallax, and moderate-resolution spectroscopy can better constrain the system's age and how HD 1160 B fits within the context of (sub)stellar evolution.« less

SCExAO and GPI Y JH band photometry and integral field spectroscopy of the young brown dwarf companion to HD 1160

DOE PAGES

Garcia, Eugenio Victor; Currie, Thayne; Guyon, Olivier; ...

2017-01-10

Here, we present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957–1.120 μm) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5more » $${}_{-0.5}^{+1.0}$$, where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000–3100 K, a surface gravity of log g = 4–4.5, a radius of 1.55 ± 0.10 R J, and a luminosity of log L/L ⊙ = –2.76 ± 0.05. Neither the primary's Hertzspring–Russell diagram position nor atmospheric modeling of HD 1160 B show evidence for a subsolar metallicity. Interpretation of the HD 1160 B spectroscopy depends on which stellar system components are used to estimate the age. Considering HD 1160 A, B and C jointly, we derive an age of 80–125 Myr, implying that HD 1160 B straddles the hydrogen-burning limit (70–90 M J). If we consider HD 1160 A alone, younger ages (20–125 Myr) and a brown dwarf-like mass (35–90 M J) are possible. Interferometric measurements of the primary, a precise Gaia parallax, and moderate-resolution spectroscopy can better constrain the system's age and how HD 1160 B fits within the context of (sub)stellar evolution.« less

No Snowball on Habitable Tidally Locked Planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Checlair, Jade; Abbot, Dorian S.; Menou, Kristen, E-mail: jadecheclair@uchicago.edu

The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of globalmore » glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.« less

IMAGES: An IMage Archive Generated for Exoplanet Surveys

NASA Astrophysics Data System (ADS)

Tanner, A.

2010-10-01

In the past few years, there have been a menagerie of high contrast imaging surveys which have resulted in the detection of the first brown dwarfs orbiting main sequence stars and the first directly imaged exo-planetary systems. While these discoveries are scientifically rewarding, they are rare and the majority of the images collected during these surveys show single target stars. In addition, while papers will report the number of companion non-detections down to a sensitivity limit at a specific distance from the star, the corresponding images are rarely made available to the public. To date, such data exists for over a thousand stars. Thus, we are creating IMAGES, the IMage Archive Generated for Exoplanet Searches, as a repository for high contrast images gathered from published direct imaging sub-stellar and exoplanet companion surveys. This database will serve many purposes such as 1) facilitating common proper motion confirmation for candidate companions, 2) reducing the number of redundant observations of non-detection fields, 3) providing multiplicity precursor information to better select targets for future exoplanet missions, 4) providing stringent limits on the companion fraction of stars for a wide range of age, spectral type and star formation environment, and 5) provide multi-epoch images of stars with known companions for orbital monitoring. This database will be open to the public and will be searchable and sortable and will be extremely useful for future direct imaging programs such as GPI and SPHERE as well as future planet search programs such as JWST and SIM.

A Jupiter-mass planet around the K0 giant HD 208897

NASA Astrophysics Data System (ADS)

Yılmaz, M.; Sato, B.; Bikmaev, I.; Selam, S. O.; Izumiura, H.; Keskin, V.; Kambe, E.; Melnikov, S. S.; Galeev, A.; Özavcı, İ.; Irtuganov, E. N.; Zhuchkov, R. Ya.

2017-11-01

For over 10 years, we have carried out a precise radial velocity (RV) survey to find substellar companions around evolved G, K-type stars to extend our knowledge of planet formation and evolution. We performed high precision RV measurements for the giant star HD 208897 using an iodine (I2) absorption cell. The measurements were made at TÜBİTAK National Observatory (TUG; RTT150) and Okayama Astrophysical Observatory (OAO). For the origin of the periodic variation seen in the RV data of the star, we adopted a Keplerian motion caused by an unseen companion. We found that the star hosts a planet with a minimum mass of m2sini = 1.40 MJ, which is relatively low compared to those of known planets orbiting evolved intermediate-mass stars. The planet is in a nearly circular orbit with a period of P = 353 days at about 1 AU distance from the host star. The star is metal rich and located at the early phase of ascent along the red giant branch. The photometric observations of the star at Ankara University Kreiken Observatory (AUKR) and the Hipparcos photometry show no sign of variation with periods associated with the RV variation. Neither bisector velocity analysis nor analysis of the Ca II and Hα lines shows any correlation with the RV measurements. This work was supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK), the project number of 114F099.

A map of the day-night contrast of the extrasolar planet HD 189733b.

PubMed

Knutson, Heather A; Charbonneau, David; Allen, Lori E; Fortney, Jonathan J; Agol, Eric; Cowan, Nicolas B; Showman, Adam P; Cooper, Curtis S; Megeath, S Thomas

2007-05-10

'Hot Jupiter' extrasolar planets are expected to be tidally locked because they are close (<0.05 astronomical units, where 1 au is the average Sun-Earth distance) to their parent stars, resulting in permanent daysides and nightsides. By observing systems where the planet and star periodically eclipse each other, several groups have been able to estimate the temperatures of the daysides of these planets. A key question is whether the atmosphere is able to transport the energy incident upon the dayside to the nightside, which will determine the temperature at different points on the planet's surface. Here we report observations of HD 189733, the closest of these eclipsing planetary systems, over half an orbital period, from which we can construct a 'map' of the distribution of temperatures. We detected the increase in brightness as the dayside of the planet rotated into view. We estimate a minimum brightness temperature of 973 +/- 33 K and a maximum brightness temperature of 1,212 +/- 11 K at a wavelength of 8 mum, indicating that energy from the irradiated dayside is efficiently redistributed throughout the atmosphere, in contrast to a recent claim for another hot Jupiter. Our data indicate that the peak hemisphere-integrated brightness occurs 16 +/- 6 degrees before opposition, corresponding to a hotspot shifted east of the substellar point. The secondary eclipse (when the planet moves behind the star) occurs 120 +/- 24 s later than predicted, which may indicate a slightly eccentric orbit.

No Snowball on Habitable Tidally Locked Planets

NASA Astrophysics Data System (ADS)

Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

2017-08-01

The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

VizieR Online Data Catalog: Spectroscopy of very low mass objects (Patience+, 2012)

NASA Astrophysics Data System (ADS)

Patience, J.; King, R. R.; De Rosa, R. J.; Vigan, A.; Witte, S.; Rice, E.; Helling, C.; Hauschildt, P.

2012-09-01

With a uniform VLT SINFONI data set of nine targets, we have developed an empirical grid of J, H, K spectra of the atmospheres of objects estimated to have very low substellar masses of ~5-20MJup and young ages ranging from ~1-50Myr. Most of the targets are companions, objects which are especially valuable for comparison with atmosphere and evolutionary models, as they present rare cases in which the age is accurately known from the primary. Based on the youth of the sample, all objects are expected to have low surface gravity, and this study investigates the critical early phases of the evolution of substellar objects. The spectra are compared with grids of five different theoretical atmosphere models. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************

New spectro-photometric characterization of the substellar object HR 2562 B using SPHERE

NASA Astrophysics Data System (ADS)

Mesa, D.; Baudino, J.-L.; Charnay, B.; D'Orazi, V.; Desidera, S.; Boccaletti, A.; Gratton, R.; Bonnefoy, M.; Delorme, P.; Langlois, M.; Vigan, A.; Zurlo, A.; Maire, A.-L.; Janson, M.; Antichi, J.; Baruffolo, A.; Bruno, P.; Cascone, E.; Chauvin, G.; Claudi, R. U.; De Caprio, V.; Fantinel, D.; Farisato, G.; Feldt, M.; Giro, E.; Hagelberg, J.; Incorvaia, S.; Lagadec, E.; Lagrange, A.-M.; Lazzoni, C.; Lessio, L.; Salasnich, B.; Scuderi, S.; Sissa, E.; Turatto, M.

2018-05-01

Aims: HR 2562 is an F5V star located at 33 pc from the Sun hosting a substellar companion that was discovered using the Gemini planet imager (GPI) instrument. The main objective of the present paper is to provide an extensive characterization of the substellar companion, by deriving its fundamental properties. Methods: We observed HR 2562 with the near-infrared branch composed by the integral field spectrograph (IFS) and the infrared dual band spectrograph (IRDIS) of the spectro-polarimetric high-contrast exoplanet research (SPHERE) instrument at the very large telescope (VLT). During our observations IFS was operating in the Y J band, while IRDIS was observing with the H broadband filter. The data were reduced with the dedicated SPHERE GTO pipeline, which is custom designed for this instrument. On the reduced images, we then applied the post-processing procedures that are specifically prepared to subtract the speckle noise. Results: The companion is clearly detected in both IRDIS and IFS datasets. We obtained photometry in three different spectral bands. The comparison with template spectra allowed us to derive a spectral type of T2-T3 for the companion. Using both evolutionary and atmospheric models we inferred the main physical parameters of the companion obtaining a mass of 32 ± 14 MJup, Teff = 1100 ± 200 K, and log g = 4.75 ± 0.41. Based on observations made with European Southern Observatory (ESO) telescopes at Paranal Observatory in Chile, under program ID 198.C-0209(D).

The structure of motion in a 4-component galaxy mass model

NASA Astrophysics Data System (ADS)

Caranicolas, N. D.

1996-03-01

We use a composite galaxy model consisting of a disk-halo, bulge, nucleus and dark-halo components in order to investigate the motion of stars in ther-z plane. It is observed that high angular momentum stars move in regular orbits. The majority of orbits are box orbits. There are also banana-like orbits. For a given value of energy, only a fraction of the low angular momentum stars — those going near the nucleus — show chaotic motion while the rest move in regular orbits. Again one observes the above two kinds of orbits. In addition to the above one can also see orbits with the characteristics of the 2/3 and 3/4 resonance. It is also shown that, in the absence of the bulge component, the area of chaotic motion in the surface of section increases, significantly. This suggests that a larger number of low angular momentum stars are in chaotic orbits in galaxies with massive nuclei and no bulge components.

Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object

NASA Astrophysics Data System (ADS)

Zhang, Z. H.; Homeier, D.; Pinfield, D. J.; Lodieu, N.; Jones, H. R. A.; Allard, F.; Pavlenko, Ya. V.

2017-06-01

SDSS J010448.46+153501.8 has previously been classified as an sdM9.5 subdwarf. However, its very blue J - K colour (-0.15 ± 0.17) suggests a much lower metallicity compared to normal sdM9.5 subdwarfs. Here, we re-classify this object as a usdL1.5 subdwarf based on a new optical and near-infrared spectrum obtained with X-shooter on the Very Large Telescope. Spectral fitting with BT-Settl models leads to Teff = 2450 ± 150 K, [Fe/H] = -2.4 ± 0.2 and log g = 5.5 ± 0.25. We estimate a mass for SDSS J010448.46+153501.8 of 0.086 ± 0.0015 M⊙ which is just below the hydrogen-burning minimum mass at [Fe/H] = -2.4 (˜0.088 M⊙) according to evolutionary models. Our analysis thus shows SDSS J010448.46+153501.8 to be the most metal-poor and highest mass substellar object known to-date. We found that SDSS J010448.46+153501.8 is joined by another five known L subdwarfs (2MASS J05325346+8246465, 2MASS J06164006-6407194, SDSS J125637.16-022452.2, ULAS J151913.03-000030.0 and 2MASS J16262034+3925190) in a 'halo brown dwarf transition zone' in the Teff-[Fe/H] plane, which represents a narrow mass range in which unsteady nuclear fusion occurs. This halo brown dwarf transition zone forms a 'substellar subdwarf gap' for mid L to early T types.

Companions and Environments of Low-Mass Stars: From Star-Forming Regions to the Field

NASA Astrophysics Data System (ADS)

Ward-Duong, Kimberly; Patience, Jenny; De Rosa, Robert J.; Bulger, Joanna; Rajan, Abhijith; Goodwin, Simon; Parker, Richard J.; McCarthy, Donald W.; Kulesa, Craig; van der Plas, Gerrit; Menard, Francois; Pinte, Christophe; Jackson, Alan Patrick; Bryden, Geoffrey; Turner, Neal J.; Harvey, Paul M.; Hales, Antonio

2017-01-01

We present results from two studies probing the multiplicity and environmental properties of low-mass stars: (1) The MinMs (M-dwarfs in Multiples) Survey, a large, volume-limited survey of 245 field M-dwarfs within 15 pc, and (2) the TBOSS (Taurus Boundary of Stellar/Substellar) Survey, an ongoing study of disk properties for the lowest-mass members within the Taurus star-forming region. The MinMs Survey provides new measurements of the companion star fraction, separation distribution, and mass ratio distribution for the nearest K7-M6 dwarfs, utilizing a combination of high-resolution adaptive optics imaging and digitized widefield archival plates to cover an unprecedented separation range of ~1-10,000 AU. Within these data, we also identify companions below the stellar/brown dwarf boundary, enabling characterization of the substellar companion population to low-mass field stars. For the much younger population in Taurus, we present results from ALMA Band 7 continuum observations of low-mass stellar and substellar Class II objects, spanning spectral types from M4-M7.75. The sub-millimeter detections of these disks provide key estimates of the dust mass in small grains, which is then assessed within the context of region age, environment, and viability for planet formation. This young population also includes a number of interesting young binary systems. Covering both young (1-2 Myr) and old (>5 Gyr) populations of low-mass stars, the results from these studies provide benchmark measurements on the population statistics of low-mass field stars, and on the early protoplanetary environments of their younger M-star counterparts.

An investigation of a super-Earth exoplanet with a greenhouse-gas atmosphere using a general circulation model

NASA Astrophysics Data System (ADS)

Zalucha, Angela M.; Michaels, Timothy I.; Madhusudhan, Nikku

2013-11-01

We use the Massachusetts Institute of Technology general circulation model (GCM) dynamical core, in conjunction with a Newtonian relaxation scheme that relaxes to a gray, analytical solution of the radiative transfer equation, to simulate a tidally locked, synchronously orbiting super-Earth exoplanet. This hypothetical exoplanet is simulated under the following main assumptions: (1) the size, mass, and orbital characteristics of GJ 1214b (Charbonneau, D. [2009]. Nature 462, 891-894), (2) a greenhouse-gas dominated atmosphere, (3), the gas properties of water vapor, and (4) a surface. We have performed a parameter sweep over global mean surface pressure (0.1, 1, 10, and 100 bar) and global mean surface albedo (0.1, 0.4, and 0.7). Given assumption (1) above, the period of rotation of this exoplanet is 1.58 Earth-days, which we classify as the rapidly rotating regime. Our parameter sweep differs from Heng and Vogt (Heng, K., Vogt, S.S. [2011]. Mon. Not. R. Astron. Soc. 415, 2145-2157), who performed their study in the slowly rotating regime and using Held and Suarez (Held, I.M., Suarez, M.J. [1994]. Bull. Am. Meteorol. Soc. 75 (10), 1825-1830) thermal forcing. This type of thermal forcing is a prescribed function, not related to any radiative transfer, used to benchmark Earth’s atmosphere. An equatorial, westerly, superrotating jet is a robust feature in our GCM results. This equatorial jet is westerly at all longitudes. At high latitudes, the flow is easterly. The zonal winds do show a change with global mean surface pressure. As global mean surface pressure increases, the speed of the equatorial jet decreases between 9 and 15 h local time (substellar point is located at 12 h local time). The latitudinal extent of the equatorial jet increases on the nightside. For the two greatest initial surface pressure cases, an increasingly westerly component of flow develops at middle to high latitudes between 11 and 18 h local time. On the nightside, the easterly flow in the midlatitudes also increases in speed as global mean surface pressure increases. Furthermore, the zonal wind speed in the equatorial and midlatitude jets decreases with increasing surface albedo. Also, the latitudinal width of the equatorial jet decreases as surface albedo increases.

Roles of NN-interaction components in shell-structure evolution

NASA Astrophysics Data System (ADS)

Umeya, Atsushi; Muto, Kazuo

2016-11-01

Since the importance of the monopole interaction was first emphasized in 1960s, roles of monopole strengths of two-body nucleon-nucleon interaction in shell structure have been discussed. Through the monopole strengths, we study the roles in shell-structure evolution, starting from explicit forms of the interaction. For the tensor component of the interaction, we show the derivation of the relation, (2j> + 1)Vjj> + (2j< + 1)Vjj< = 0, with a detailed manipulation. We show that one-body spin-orbit term appears in the multipole expansion of two-body spin-orbit interaction. Only the spin-orbit components can affect the spin-orbit energy splitting between spin-orbit partners, when the spin-orbit partner orbits are fully occupied.

Rotation of Giant Stars

NASA Astrophysics Data System (ADS)

Kissin, Yevgeni; Thompson, Christopher

2015-07-01

The internal rotation of post-main sequence stars is investigated, in response to the convective pumping of angular momentum toward the stellar core, combined with a tight magnetic coupling between core and envelope. The spin evolution is calculated using model stars of initial mass 1, 1.5, and 5 {M}⊙ , taking into account mass loss on the giant branches. We also include the deposition of orbital angular momentum from a sub-stellar companion, as influenced by tidal drag along with the excitation of orbital eccentricity by a fluctuating gravitational quadrupole moment. A range of angular velocity profiles {{Ω }}(r) is considered in the envelope, extending from solid rotation to constant specific angular momentum. We focus on the backreaction of the Coriolis force, and the threshold for dynamo action in the inner envelope. Quantitative agreement with measurements of core rotation in subgiants and post-He core flash stars by Kepler is obtained with a two-layer angular velocity profile: uniform specific angular momentum where the Coriolis parameter {Co}\\equiv {{Ω }}{τ }{con}≲ 1 (here {τ }{con} is the convective time), and {{Ω }}(r)\\propto {r}-1 where {Co}≳ 1. The inner profile is interpreted in terms of a balance between the Coriolis force and angular pressure gradients driven by radially extended convective plumes. Inward angular momentum pumping reduces the surface rotation of subgiants, and the need for a rejuvenated magnetic wind torque. The co-evolution of internal magnetic fields and rotation is considered in Kissin & Thompson, along with the breaking of the rotational coupling between core and envelope due to heavy mass loss.

The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f.

PubMed

Shields, Aomawa L; Barnes, Rory; Agol, Eric; Charnay, Benjamin; Bitz, Cecilia; Meadows, Victoria S

2016-06-01

As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013 ), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of orbital and atmospheric properties that permit surface liquid water on Kepler-62f. Extrasolar planets-Habitability-Planetary environments. Astrobiology 16, 443-464.

The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f

PubMed Central

Barnes, Rory; Agol, Eric; Charnay, Benjamin; Bitz, Cecilia; Meadows, Victoria S.

2016-01-01

Abstract As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of orbital and atmospheric properties that permit surface liquid water on Kepler-62f. Key Words: Extrasolar planets—Habitability—Planetary environments. Astrobiology 16, 443–464. PMID:27176715

Particle orbits in model current sheet with a nonzero B(y) component

NASA Technical Reports Server (NTRS)

Zhu, Zhongwei; Parks, George

1993-01-01

The problem of charged particle motions in magnetotaillike model current sheets is revisited with the inclusion of a nonzero dawn-dusk magnetic field component. Three cases are examined considering both trapped and escaped orbits. The results show that a nonzero B(y) component disturbs the particle orbits by destroying orbit symmetry in the phase space about the z = 0 plane. It also changes the bounce frequency of particle orbits. The presence of B(y) thus modifies the Speiser orbits, particularly near the ejection phase. The process of ejected particle such as ejection direction, ejection velocity, and pitch angles are shown to depend on the sign of the charge.

Imaging Protoplanets: Observing Transition Disks with Non-Redundant Masking

NASA Astrophysics Data System (ADS)

Sallum, Stephanie

2017-01-01

Transition disks - protoplanetary disks with inner, solar system sized clearings - may be shaped by young planets. Directly imaging protoplanets in these objects requires high contrast and resolution, making them promising targets for future extremely large telescopes. The interferometric technique of non-redundant masking (NRM) is well suited for these observations, enabling companion detection for contrasts of 1:100 - 1:1000 at or within the diffraction limit. My dissertation focuses on searching for and characterizing companions in transition disk clearings using NRM. I will briefly describe the technique and present spatially resolved observations of the T Cha and LkCa 15 transition disks. Both of these objects hosted posited substellar companions. However multi-epoch T Cha datasets cannot be explained by planets orbiting in the disk plane. Conversely, LkCa 15 data taken with the Large Binocular Telescope (LBT) in single-aperture mode reveal the presence of multiple forming planets. The dual aperture LBT will provide triple the angular resolution of these observations, dramatically increasing the phase space for exoplanet detection. I will also present new results from the dual-aperture LBT, with similar resolution to that expected for next generation facilities like GMT.

Race to the Top: Transiting Brown Dwarfs and Hot Jupiters

NASA Astrophysics Data System (ADS)

Beatty, Thomas G.

2015-12-01

There are currently twelve known transiting brown dwarfs, nine of which orbit single main-sequence stars. These systems give us one of the only ways in which we may directly measure the masses and radii brown dwarfs, which in turn provides strong constraints on theoretical models of brown dwarf interiors and atmospheres. In addition, the transiting brown dwarfs allow us to forge a link between our understanding of transiting hot Jupiters, and our understanding of the field brown dwarf population. Comparing the two gives us a unique avenue to explore the role and interaction of surface gravity and stellar irradiation in the atmospheres of sub-stellar objects. It also allows us to leverage the detailed spectroscopic information we have for field brown dwarfs to interpret the broadband colors of hot Jupiters. This provides us with insight into the L/T transition in brown dwarfs, and the atmospheric chemistry changes that occur in hot Jupiter atmospheres as they cool. I will discuss recent observational results, with a particular focus on the transiting brown dwarf KELT-1b, and suggest how more of these important systems may be discovered in the future.

ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Nikole K.; Showman, Adam P.; Knutson, Heather A.

2013-04-01

We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands of the Spitzer Space Telescope. The 3.6 and 4.5 {mu}m data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 {mu}m that robustly maps position-dependent flux variations. Wemore » find that the peak in planetary flux occurs at 4.39 {+-} 0.28, 5.84 {+-} 0.39, and 4.68 {+-} 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% {+-} 0.0089%, 0.1162% {+-} 0.0080%, and 0.1888% {+-} 0.0072% in the 3.6, 4.5, and 8.0 {mu}m bands, respectively. Our measured secondary eclipse depths of 0.0996% {+-} 0.0072%, 0.1031% {+-} 0.0061%, 0.071%{sub -0.013%}{sup +0.029,} and 0.1392% {+-} 0.0095% in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 {+-} 0.00048) and argument of periapse ({omega} = 188. Degree-Sign 09 {+-} 0. Degree-Sign 39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long-term linear trend in the radial velocity data. This trend suggests the presence of another substellar companion in the HAT-P-2 system, which could have caused HAT-P-2b to migrate inward to its present-day orbit via the Kozai mechanism.« less

Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2017-08-01

We propose to obtain WFC3/IR imaging of the very coolest brown dwarfs (T < 800 K) to search for substellar and planetary-mass companions to these objects. Companions discovered by this program would likely be analogues of the 250 K brown dwarf WISE 0855 and would provide vital benchmark objects for theoretical models, closing the gap in mass and temperature between brown dwarfs and planets. Finding such an object as a member of a binary system would be even more valuable as it would allow for the measurement of dynamical masses. We recently placed the first constraints to date on the binary frequency for brown dwarfs with spectral types >T8. This program will triple our current sample size, a requirement in order to confirm our current results and compare substellar binary properties for various spectral type and age populations. The WFC3/IR plate will allow us to probe near equal-mass binaries down to separations of 0.2 (2-3 AU for the typical distances of our targets). True cool companions should show strong absorption around 1.4 um as a result of the deep water absorption band observed at that wavelength in substellar spectra. We therefore propose observations in the WFC3 F127M and F139M filters which will allow us to robustly identify bona fide candidates and distinguish them from background stars based on this spectral feature. Most of our targets lack suitable NGS AO guide stars or LGS AO tip-tilt stars to be observed with ground-based telescopes, and the 1.4 um water band is often unobservable from the ground due to telluric water absorption. WFC3 on HST is thus the only instrument suitable for these observations.

CHARACTERIZING THE BROWN DWARF FORMATION CHANNELS FROM THE INITIAL MASS FUNCTION AND BINARY-STAR DYNAMICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thies, Ingo; Pflamm-Altenburg, Jan; Kroupa, Pavel

2015-02-10

The stellar initial mass function (IMF) is a key property of stellar populations. There is growing evidence that the classical star-formation mechanism by the direct cloud fragmentation process has difficulties reproducing the observed abundance and binary properties of brown dwarfs and very-low-mass stars. In particular, recent analytical derivations of the stellar IMF exhibit a deficit of brown dwarfs compared to observational data. Here we derive the residual mass function of brown dwarfs as an empirical measure of the brown dwarf deficiency in recent star-formation models with respect to observations and show that it is compatible with the substellar part ofmore » the Thies-Kroupa IMF and the mass function obtained by numerical simulations. We conclude that the existing models may be further improved by including a substellar correction term that accounts for additional formation channels like disk or filament fragmentation. The term ''peripheral fragmentation'' is introduced here for such additional formation channels. In addition, we present an updated analytical model of stellar and substellar binarity. The resulting binary fraction and the dynamically evolved companion mass-ratio distribution are in good agreement with observational data on stellar and very-low-mass binaries in the Galactic field, in clusters, and in dynamically unprocessed groups of stars if all stars form as binaries with stellar companions. Cautionary notes are given on the proper analysis of mass functions and the companion mass-ratio distribution and the interpretation of the results. The existence of accretion disks around young brown dwarfs does not imply that these form just like stars in direct fragmentation.« less

Geothermal heating enhances atmospheric asymmetries on synchronously rotating planets

NASA Astrophysics Data System (ADS)

Haqq-Misra, Jacob; Kopparapu, Ravi Kumar

2015-01-01

Earth-like planets within the liquid water habitable zone of M-type stars may evolve into synchronous rotators. On these planets, the substellar hemisphere experiences perpetual daylight while the opposing antistellar hemisphere experiences perpetual darkness. Because the night-side hemisphere has no direct source of energy, the air over this side of the planet is prone to freeze out and deposit on the surface, which could result in atmospheric collapse. However, general circulation models (GCMs) have shown that atmospheric dynamics can counteract this problem and provide sufficient energy transport to the antistellar side. Here, we use an idealized GCM to consider the impact of geothermal heating on the habitability of synchronously rotating planets. Geothermal heating may be expected due to tidal interactions with the host star, and the effects of geothermal heating provide additional habitable surface area and may help to induce melting of ice on the antistellar hemisphere. We also explore the persistence of atmospheric asymmetries between the Northern and Southern hemispheres, and we find that the direction of the meridional circulation (for rapidly rotating planets) or the direction of zonal wind (for slowly rotating planets) reverses on either side of the substellar point. We show that the zonal circulation approaches a theoretical state similar to a Walker circulation only for slowly rotating planets, while rapidly rotating planets show a zonal circulation with the opposite direction. We find that a cross-polar circulation is present in all cases and provides an additional mechanism of mass and energy transport from the substellar to antistellar point. Characterization of the atmospheres of synchronously rotating planets should include consideration of hemispheric differences in meridional circulation and examination of transport due to cross-polar flow.

A Pan-STARRS1 Proper-Motion Survey for Young Brown Dwarfs in the Nearest Star-Forming Regions and a Reddening-Free Classification Method for Ultracool Dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene; Aller, Kimberly

2018-01-01

Young brown dwarfs are of prime importance to investigate the universality of the initial mass function (IMF). Based on photometry and proper motions from the Pan-STARRS1 (PS1) 3π survey, we are conducting the widest and deepest brown dwarf survey in the nearby star-forming regions, Taurus–Auriga (Taurus) and Upper Scorpius (USco). Our work is the first to measure proper motions, a robust proxy of membership, for brown dwarf candidates in Taurus and USco over such a large area and long time baseline (≈ 15 year) with such high precision (≈ 4 mas yr-1). Since extinction complicates spectral classification, we have developed a new approach to quantitatively determine reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≈ 100–5 MJup), using low-resolution near-infrared spectra. So far, our IRTF/SpeX spectroscopic follow-up has increased the substellar and planetary-mass census of Taurus by ≈ 50% and almost doubled the substellar census of USco, constituting the largest single increases of brown dwarfs and free-floating planets found in both regions to date. Most notably, our new discoveries reveal an older (> 10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. In addition, the mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes. Upon completion, our survey will establish the most complete substellar and planetary-mass census in both Taurus and USco associations, make a significant addition to the low-mass IMF in both regions, and deliver more comprehensive pictures of star formation histories.

Deficit of Wide Binaries in the η Chamaeleontis Young Cluster

NASA Astrophysics Data System (ADS)

Brandeker, Alexis; Jayawardhana, Ray; Khavari, Parandis; Haisch, Karl E., Jr.; Mardones, Diego

2006-12-01

We have carried out a sensitive high-resolution imaging survey of stars in the young (6-8 Myr), nearby (97 pc) compact cluster around η Chamaeleontis to search for stellar and substellar companions. Our data were obtained using the NACO adaptive optics system on the ESO Very Large Telescope (VLT). Given its youth and proximity, any substellar companions are expected to be luminous, especially in the near-infrared, and thus easier to detect next to their parent stars. Here, we present VLT NACO adaptive optics imaging with companion detection limits for 17 η Cha cluster members, and follow-up VLT ISAAC near-infrared spectroscopy for companion candidates. The widest binary detected is ~0.2", corresponding to the projected separation 20 AU, despite our survey being sensitive down to substellar companions outside 0.3", and planetary-mass objects outside 0.5". This implies that the stellar companion probability outside 0.3" and the brown dwarf companion probability outside 0.5" are less than 0.16 with 95% confidence. We compare the wide binary frequency of η Cha to that of the similarly aged TW Hydrae association and estimate the statistical likelihood that the wide binary probability is equal in both groups to be less than 2×10-4. Even though the η Cha cluster is relatively dense, stellar encounters in its present configuration cannot account for the relative deficit of wide binaries. We thus conclude that the difference in wide binary probability in these two groups provides strong evidence for multiplicity properties being dependent on environment. In two appendices we derive the projected separation probability distribution for binaries, used to constrain physical separations from observed projected separations, and summarize statistical tools useful for multiplicity studies.

Orbital decomposition of CALIFA spiral galaxies

NASA Astrophysics Data System (ADS)

Zhu, Ling; van den Bosch, Remco; van de Ven, Glenn; Lyubenova, Mariya; Falcón-Barroso, Jesús; Meidt, Sharon E.; Martig, Marie; Shen, Juntai; Li, Zhao-Yu; Yildirim, Akin; Walcher, C. Jakob; Sanchez, Sebastian F.

2018-01-01

Schwarzschild orbit-based dynamical models are widely used to uncover the internal dynamics of early-type galaxies and globular clusters. Here we present for the first time the Schwarzschild models of late-type galaxies: an SBb galaxy NGC 4210 and an S0 galaxy NGC 6278 from the Calar Alto Legacy Integral Field Area (CALIFA) survey. The mass profiles within 2Re are constrained well with 1σ statistical error of ∼ 10 per cent. The luminous and dark mass can be disentangled with uncertainties of ∼20 and ∼ 50 per cent, respectively. From Re to 2Re, the dark matter fraction increases from 14 ± 10 to 18 ± 10 per cent for NGC 4210 and from 15 ± 10 to 30 ± 20 per cent for NGC 6278. The velocity anisotropy profiles of both σr/σt and σz/σR are well constrained. The inferred internal orbital distributions reveal clear substructures. The orbits are naturally separated into three components: a cold component with near circular orbits; a hot component with near radial orbits and a warm component in between. The photometrically identified exponential discs are predominantly made up of cold orbits only beyond ∼1Re, while they are constructed mainly with the warm orbits inside. Our dynamical hot components are concentrated in the inner regions, similar to the photometrically identified bulges. The reliability of the results, especially the orbit distribution, is verified by applying the model to mock data.

The discovery of the peculiar L dwarf ULAS J222711-004547

NASA Astrophysics Data System (ADS)

Marocco, F.; Day-Jones, A. C.; Jones, H. R. A.; Pinfield, D. J.; Burningham, B.; Zhang, Z. H.

We present the discovery of a very peculiar L dwarf from the UKIDSS Large Area Survey (LAS), ULAS J222711-004547. Its very red infrared colours (MKO J-K = 2.79) make it the reddest brown dwarf discovered so far. The object was discovered as part of a large spectroscopic campaign aimed at constraining the sub-stellar birth rate. We obtained a moderate resolution spectrum of this target using the echelle spectrograph XSHOOTER on VLT/UT2, and classified it as L7pec, confirming its very red nature. We show that applying a simple de-reddening curve to the spectrum of ULAS J222711-004547, this becomes very similar to the spectrum of a L7 spectroscopic standard. Therefore we conclude that the reddening of the spectrum is mostly due to an excess of dust in the photosphere of the object. This new discovery joins the list of unusually red L dwarfs, whose nature is not yet fully understood, and poses a new important challenge to atmospheric modeling of substellar objects.

Precise Ages for the Benchmark Brown Dwarfs HD 19467 B and HD 4747 B

NASA Astrophysics Data System (ADS)

Wood, Charlotte; Boyajian, Tabetha; Crepp, Justin; von Braun, Kaspar; Brewer, John; Schaefer, Gail; Adams, Arthur; White, Tim

2018-01-01

Large uncertainty in the age of brown dwarfs, stemming from a mass-age degeneracy, makes it difficult to constrain substellar evolutionary models. To break the degeneracy, we need ''benchmark" brown dwarfs (found in binary systems) whose ages can be determined independent of their masses. HD~19467~B and HD~4747~B are two benchmark brown dwarfs detected through the TRENDS (TaRgeting bENchmark objects with Doppler Spectroscopy) high-contrast imaging program for which we have dynamical mass measurements. To constrain their ages independently through isochronal analysis, we measured the radii of the host stars with interferometry using the Center for High Angular Resolution Astronomy (CHARA) Array. Assuming the brown dwarfs have the same ages as their host stars, we use these results to distinguish between several substellar evolutionary models. In this poster, we present new age estimates for HD~19467 and HD~4747 that are more accurate and precise and show our preliminary comparisons to cooling models.

Morphology and kinematics of orbital components in CALIFA galaxies across the Hubble sequence

NASA Astrophysics Data System (ADS)

Zhu, Ling; van de Ven, Glenn; Méndez-Abreu, Jairo; Obreja, Aura

2018-06-01

Based on the stellar orbit distribution derived from orbit-superposition Schwarzschild models, we decompose each of 250 representative present-day galaxies into four orbital components: cold with strong rotation, warm with weak rotation, hot with dominant random motion and counter-rotating (CR). We rebuild the surface brightness (Σ) of each orbital component and we present in figures and tables a quantification of their morphologies using the Sersic index n, concentration C = log {(Σ _{0.1R_e}/Σ _{R_e})} and intrinsic flattening qRe and qRmax, with Re the half-light-radius and Rmax the CALIFA data coverage. We find that: (1) kinematic hotter components are generally more concentrated and rounder than colder components, and (2) all components become more concentrated and thicker/rounder in more massive galaxies; they change from disk-like in low mass late-type galaxies to bulge-like in high-mass early type galaxies. Our findings suggest that Sersic n is not a good discriminator between rotating bulges and non-rotating bulges. The luminosity fraction of cold orbits fcold is well correlated with the photometrically-decomposed disk fraction fdisk as f_{cold} = 0.14 + 0.23f_{disk}. Similarly, the hot orbit fraction fhot is correlated with the bulge fraction fbulge as f_{hot} = 0.19 + 0.31f_{bulge}. The warm orbits mainly contribute to disks in low-mass late-type galaxies, and to bulges in high-mass early-type galaxies. The cold, warm, and hot components generally follow the same morphology (ɛ = 1 - qRmax) versus kinematics (σ _z^2/\\overline{V_{tot}^2}) relation as the thin disk, thick disk/pseudo bulge, and classical bulge identified from cosmological simulations.

A substellar-mass protostar and its outflow of IRAS 15398–3359 revealed by subarcsecond-resolution observations of H{sub 2}CO and CCH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oya, Yoko; Sakai, Nami; Watanabe, Yoshimasa

2014-11-10

Subarcsecond (0.''5) images of H{sub 2}CO and CCH line emission have been obtained in the 0.8 mm band toward the low-mass protostar IRAS 15398–3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about 20°, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast to previous suggestions of a more pole-onmore » geometry. The centrally concentrated component is interpreted by use of a model of the infalling rotating envelope with the estimated inclination angle and the mass of the protostar is estimated to be less than 0.09 M {sub ☉}. Higher spatial resolution data are needed to infer the presence of a rotationally supported disk for this source, hinted at by a weak high-velocity H{sub 2}CO emission associated with the protostar.« less

A deep staring campaign in the σ Orionis cluster. Variability in substellar members

NASA Astrophysics Data System (ADS)

Elliott, P.; Scholz, A.; Jayawardhana, R.; Eislöffel, J.; Hébrard, E. M.

2017-12-01

Context. The young star cluster near σ Orionis is one of the primary environments to study the properties of young brown dwarfs down to masses comparable to those of giant planets. Aims: Deep optical imaging is used to study time-domain properties of young brown dwarfs over typical rotational timescales and to search for new substellar and planetary-mass cluster members. Methods: We used the Visible Multi Object Spectrograph (VIMOS) at the Very Large Telescope (VLT) to monitor a 24'× 16' field in the I-band. We stared at the same area over a total integration time of 21 h, spanning three observing nights. Using the individual images from this run we investigated the photometric time series of nine substellar cluster members with masses from 10 to 60 MJup. The deep stacked image shows cluster members down to ≈5 MJup. We searched for new planetary-mass objects by combining our deep I-band photometry with public J-band magnitudes and by examining the nearby environment of known very low mass members for possible companions. Results: We find two brown dwarfs, with significantly variable, aperiodic light curves, both with masses around 50 MJup, one of which was previously unknown to be variable. The physical mechanism responsible for the observed variability is likely to be different for the two objects. The variability of the first object, a single-lined spectroscopic binary, is most likely linked to its accretion disc; the second may be caused by variable extinction by large grains. We find five new candidate members from the colour-magnitude diagram and three from a search for companions within 2000 au. We rule all eight sources out as potential members based on non-stellar shape and/or infrared colours. The I-band photometry is made available as a public dataset. Conclusions: We present two variable brown dwarfs. One is consistent with ongoing accretion, the other exhibits apparent transient variability without the presence of an accretion disc. Our analysis confirms the existing census of substellar cluster members down to ≈7 MJup. The zero result from our companion search agrees with the low occurrence rate of wide companions to brown dwarfs found in other works. Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 078.C-0042.Full Table B.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A66

Substellar fragmentation in self-gravitating fluids with a major phase transition

NASA Astrophysics Data System (ADS)

Füglistaler, A.; Pfenniger, D.

2015-06-01

Context. The observation of various ices in cold molecular clouds, the existence of ubiquitous substellar, cold H2 globules in planetary nebulae and supernova remnants, or the mere existence of comets suggest that the physics of very cold interstellar gas might be much richer than usually envisioned. At the extreme of low temperatures (≲10 K), H2 itself is subject to a phase transition crossing the entire cosmic gas density scale. Aims: This well-known, laboratory-based fact motivates us to study the ideal case of a cold neutral gaseous medium in interstellar conditions for which the bulk of the mass, instead of trace elements, is subject to a gas-liquid or gas-solid phase transition. Methods: On the one hand, the equilibrium of general non-ideal fluids is studied using the virial theorem and linear stability analysis. On the other hand, the non-linear dynamics is studied using computer simulations to characterize the expected formation of solid bodies analogous to comets. The simulations are run with a state-of-the-art molecular dynamics code (LAMMPS) using the Lennard-Jones inter-molecular potential. The long-range gravitational forces can be taken into account together with short-range molecular forces with finite limited computational resources, using super-molecules, provided the right scaling is followed. Results: The concept of super-molecule, where the phase transition conditions are preserved by the proper choice of the particle parameters, is tested with computer simulations, allowing us to correctly satisfy the Jeans instability criterion for one-phase fluids. The simulations show that fluids presenting a phase transition are gravitationally unstable as well, independent of the strength of the gravitational potential, producing two distinct kinds of substellar bodies, those dominated by gravity (planetoids) and those dominated by molecular attractive force (comets). Conclusions: Observations, formal analysis, and computer simulations suggest the possibility of the formation of substellar H2 clumps in cold molecular clouds due to the combination of phase transition and gravity. Fluids presenting a phase transition are gravitationally unstable, independent of the strength of the gravitational potential. Arbitrarily small H2 clumps may form even at relatively high temperatures up to 400-600 K, according to virial analysis. The combination of phase transition and gravity may be relevant for a wider range of astrophysical situations, such as proto-planetary disks. Figures 33-44 are available in electronic form at http://www.aanda.org

Orbits: Computer simulation

NASA Technical Reports Server (NTRS)

Muszynska, A.

1985-01-01

In rotating machinery dynamics an orbit (Lissajous curve) represents the dynamic path of the shaft centerline motion during shaft rotation and resulting precession. The orbit can be observed with an oscilloscope connected to XY promixity probes. The orbits can also be simulated by a computer. The software for HP computer simulates orbits for two cases: (1) Symmetric orbit with four frequency components with different radial amplitudes and relative phase angles; and (2) Nonsymmetric orbit with two frequency components with two different vertical/horizontal amplitudes and two different relative phase angles. Each orbit carries a Keyphasor mark (one-per-turn reference). The frequencies, amplitudes, and phase angles, as well as number of time steps for orbit computation, have to be chosen and introduced to the computer by the user. The orbit graphs can be observed on the computer screen.

The Phases Differential Astrometry Data Archive. 5. Candidate Substellar Companions to Binary Systems

DTIC Science & Technology

2010-12-01

Mathematics and Astronomy , 105-24, California Institute of Technology, Pasadena, CA 91125, USA 5 Nicolaus Copernicus Astronomical Center, Polish Academy...Blind Test with support from NASA contract NAS7-03001 (JPL 1336910). PHASES is funded in part by the California Institute of Technol- ogy Astronomy

MARVELS-1: A Face-on Double-lined Binary Star Masquerading as a Resonant Planetary System and Consideration of Rare False Positives in Radial Velocity Planet Searches

NASA Astrophysics Data System (ADS)

Wright, Jason T.; Roy, Arpita; Mahadevan, Suvrath; Wang, Sharon X.; Ford, Eric B.; Payne, Matt; Lee, Brian L.; Wang, Ji; Crepp, Justin R.; Gaudi, B. Scott; Eastman, Jason; Pepper, Joshua; Ge, Jian; Fleming, Scott W.; Ghezzi, Luan; González-Hernández, Jonay I.; Cargile, Phillip; Stassun, Keivan G.; Wisniewski, John; Dutra-Ferreira, Leticia; Porto de Mello, Gustavo F.; Maia, Márcio A. G.; Nicolaci da Costa, Luiz; Ogando, Ricardo L. C.; Santiago, Basilio X.; Schneider, Donald P.; Hearty, Fred R.

2013-06-01

We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a ~6 day orbit. We find significant (~100 m s-1) residuals to the best-fit model for the companion, and these residuals are naïvely consistent with an interior giant planet with a P = 1.965 days in a nearly perfect 3:1 period commensurability (|Pb /Pc - 3| < 10-4). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ~100 m s-1 residuals are an artifact of spectral contamination from a stellar companion contributing ~15%-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected RV companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.

GPI Spectroscopy of the Mass, Age, and Metallicity Benchmark Brown Dwarf HD 4747 B

NASA Astrophysics Data System (ADS)

Crepp, Justin R.; Principe, David A.; Wolff, Schuyler; Giorla Godfrey, Paige A.; Rice, Emily L.; Cieza, Lucas; Pueyo, Laurent; Bechter, Eric B.; Gonzales, Erica J.

2018-02-01

The physical properties of brown dwarf companions found to orbit nearby, solar-type stars can be benchmarked against independent measures of their mass, age, chemical composition, and other parameters, offering insights into the evolution of substellar objects. The TRENDS high-contrast imaging survey has recently discovered a (mass/age/metallicity) benchmark brown dwarf orbiting the nearby (d = 18.69 ± 0.19 pc), G8V/K0V star HD 4747. We have acquired follow-up spectroscopic measurements of HD 4747 B using the Gemini Planet Imager to study its spectral type, effective temperature, surface gravity, and cloud properties. Observations obtained in the H-band and K 1-band recover the companion and reveal that it is near the L/T transition (T1 ± 2). Fitting atmospheric models to the companion spectrum, we find strong evidence for the presence of clouds. However, spectral models cannot satisfactorily fit the complete data set: while the shape of the spectrum can be well-matched in individual filters, a joint fit across the full passband results in discrepancies that are a consequence of the inherent color of the brown dwarf. We also find a 2σ tension in the companion mass, age, and surface gravity when comparing to evolutionary models. These results highlight the importance of using benchmark objects to study “secondary effects” such as metallicity, non-equilibrium chemistry, cloud parameters, electron conduction, non-adiabatic cooling, and other subtleties affecting emergent spectra. As a new L/T transition benchmark, HD 4747 B warrants further investigation into the modeling of cloud physics using higher resolution spectroscopy across a broader range of wavelengths, polarimetric observations, and continued Doppler radial velocity and astrometric monitoring.

SEARCHING FOR SCATTERERS: HIGH-CONTRAST IMAGING OF YOUNG STARS HOSTING WIDE-SEPARATION PLANETARY-MASS COMPANIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryan, Marta L.; Mawet, Dimitri; Bowler, Brendan P.

2016-08-20

We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed planetary-mass companions (PMCs) on wide orbits (>50 au). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other massive bodies at smaller separations. The typical sensitivity for this survey is Δ K ∼ 12.5 at 1″. We identify eight candidate companions,more » whose masses would reach as low as one Jupiter mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M {sub Jup} bodies in these systems down to 15–50 au that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions’ eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with masses between 5 and 15 M {sub Jup} outside of 40 au in systems with PMCs is 54%.« less

Confirmation of the binary status of Chamaeleon Hα 2 - a very young low-mass binary in Chamaeleon

NASA Astrophysics Data System (ADS)

Schmidt, T. O. B.; Neuhäuser, R.; Vogt, N.; Seifahrt, A.; Roell, T.; Bedalov, A.

2008-06-01

Context: Neuhäuser & Comerón (1998, Science, 282, 83; 1999, A&A, 350, 612) presented direct imaging evidence, as well as first spectra, of several young stellar and sub-stellar M6- to M8-type objects in the Cha I dark cloud. One of these objects is Cha Hα 2, classified as brown dwarf candidate in several publications and suggested as possible binary in Neuhäuser et al. (2002, A&A, 384, 999). Aims: We have searched around Cha Hα 2 for close and faint companions with adaptive optics imaging. Methods: Two epochs of direct imaging data were taken with the Very Large Telescope (VLT) Adaptive Optics instrument NACO in February 2006 and March 2007 in Ks-band together with a Hipparcos binary for astrometric calibration. Moreover, we took a J-band image in March 2007 to get color information. We retrieved an earlier image from 2005 from the European Southern Observatory (ESO) Science Archive Facility, increasing the available time coverage. After confirmation of common proper motion, we deduce physical parameters of the objects by spectroscopy, like temperature and mass. Results: We find Cha Hα 2 to be a very close binary of 0.16 arcsec separation, having a flux ratio of 0.91, thus having almost equal brightness and indistinguishable spectral types within the errors. We show that the two tentative components of Cha Hα 2 form a common proper motion pair, and that neither component is a non-moving background object. We even find evidence for orbital motion. A combined spectrum of both stars spanning optical and near-infrared parts of the spectral energy distribution yields a temperature of 3000 ± 100 K, corresponding to a spectral type of M6 ± 1 and a surface gravity of log{g} = 4.0+0.75-0.5, both from a comparison with GAIA model atmospheres. Furthermore, we obtained an optical extinction of AV ≃ 4.3 mag from this comparison. Conclusions: We derive masses of 0.110 M⊙ (≥0.070 M⊙) and 0.124 M⊙ (≥0.077 M⊙) for the two components of Cha Hα 2, i.e., probably low-mass stars, but one component could possibly be a brown dwarf. Based on observations made with ESO telescopes at the Paranal Observatory under programme IDs 076.C-0292A, 076.C-0339B, 078.C-0535A, at the La Silla Observatory under programme ID 065.L-0144B, the Hubble Space Telescope under programme ID GO-8716 and on observations made with the European Southern Observatory telescopes obtained from the ESO/ST-ECF Science Archive Facility. Color version of Fig. [see full textsee full text] is only available in electronic form at http://www.aanda.org

Long-term orbital period behaviour of low mass ratio contact binaries GR Vir and FP Boo

NASA Astrophysics Data System (ADS)

Ćetinkaya, Halil; Soydugan, Faruk

2017-02-01

In this study, we investigated orbital period variations of two low mass ratio contact binaries GR Vir and FP Boo based on published minima times. From the O-C analysis, it was found that FP Boo indicates orbital period decrease while the period of GR Vir is increasing. Mass transfer process was used to explain increase and decrease in the orbital periods. In the O-C diagrams of both systems periodic variations also exist. Cyclic changes can be explained as being the result of a light-travel time effect via a third component around the eclipsing binaries. In order to interpret of cyclic orbital period changes for GR Vir, which has late-type components, possible magnetic activity cycles of the components have been also considered.

Separate Spectra of the Components of the Low-mass Binary L722-22

NASA Astrophysics Data System (ADS)

Chance, D.; Hershey, J.

1996-12-01

Separate spectra have been acquired of the components of the low-mass binary L722-22A,B. Using the Hubble Space Telescope Faint Object Spectrograph in the same manner described in BAAS 27,1341 for Ross 614A,B a small aperture was placed on each star, excluding the light from the other. L722-22 was discovered to be a binary by Ianna (1988, AJ 95,1226) from a small photographic photocentric orbit found in parallax observations. The ground-based work indicated L722-22B might have a mass in the brown-dwarf range, at 0.06 M_⊙ which motivated the FOS observations. However, current HST astrometric work indicates L722-22B is at the 0.1 M_⊙ level (Taff, Hershey Space Telescope Astrometry Team 75th Meeting Report, Apr 1996). Ground based CCD spectra of M dwarf standards have been provided to us by J. Davy Kirkpatrick in the 6300 to 8500 Angstroms range. Apart from the telluric lines the FOS spectra interpolate very closely into the ground-based series across this spectral range. A classification program has been written which defines a series of spectral interval ratios, does fits for the indices of the standards as a function of spectral subtype across the M3 to M7 range of standards, and inverts the fits for the four unknown spectra of Ross 614A,B and L722-22A,B. The internal formal error of the mean from the series of indices is a small fraction of a spectral subtype. The spectral types of L722-22A and B are found to be earlier by about 3/4 of a spectral subtype than Ross 614A and B, respectively. The HST astrometry and spectroscopy yield points for these 4 binary members which lie in a very narrow locus in the mass-spectral type plane and imply that single stars of types dM6 and later, have masses less than 0.08 M_⊙, presumably substellar. Support for this work was provided by NASA through grant number 06048 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

A demonstration of high precision GPS orbit determination for geodetic applications

NASA Technical Reports Server (NTRS)

Lichten, S. M.; Border, J. S.

1987-01-01

High precision orbit determination of Global Positioning System (GPS) satellites is a key requirement for GPS-based precise geodetic measurements and precise low-earth orbiter tracking, currently under study at JPL. Different strategies for orbit determination have been explored at JPL with data from a 1985 GPS field experiment. The most successful strategy uses multi-day arcs for orbit determination and includes fine tuning of spacecraft solar pressure coefficients and station zenith tropospheric delays using the GPS data. Average rms orbit repeatability values for 5 of the GPS satellites are 1.0, 1.2, and 1.7 m in altitude, cross-track, and down-track componenets when two independent 5-day fits are compared. Orbit predictions up to 24 hours outside the multi-day arcs agree within 4 m of independent solutions obtained with well tracked satellites in the prediction interval. Baseline repeatability improves with multi-day as compared to single-day arc orbit solutions. When tropospheric delay fluctuations are modeled with process noise, significant additional improvement in baseline repeatability is achieved. For a 246-km baseline, with 6-day arc solutions for GPS orbits, baseline repeatability is 2 parts in 100 million (0.4-0.6 cm) for east, north, and length components and 8 parts in 100 million for the vertical component. For 1314 and 1509 km baselines with the same orbits, baseline repeatability is 2 parts in 100 million for the north components (2-3 cm) and 4 parts in 100 million or better for east, length, and vertical components.

SOAR Adaptive Optics Observations of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Briceno, Cesar

2018-01-01

I present results from recent studies of nearby star-forming regions using the SOAR 4.1m telescope Ground-layer Adaptive Optics system.Using narrow-band Hα and [SII] imaging we discovered a spectacular extended Herbig-Haro jet powered by a 26 MJup young brown dwarf located in the vicinity of the σ Orionis cluster. The collimated structure of multiple knots spans 0.26 pc, making it a scaled down version of the parsec-length jets seen in T Tauri stars, and the first substellar analog of an HH jet system.In the ε Chamaeleon stellar group we carried out an Adaptive Optics-aided speckle imaging study of 47 members and candidate members, to characterize the multiplicity of this, one of the nearest groups of young (~3-5 Myr) stars. We resolved 10 new binary pairs, 5 previously know binaries and two triple systems. We find a companion frequency of 0.010±0.04 per decade of separation, in the 4 to 300 AU separation range, a result comparable to main sequence dwarfs in the field. However, the more massive association members, with B and A spectral types, all have companions in this separation range. Finally, we provide new constraints on the orbital elements of the ε Cha triple system.

Orbit and Dynamical Mass of the Late-T Dwarf GL 758 B

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Dupuy, Trent J.; Endl, Michael; Cochran, William D.; MacQueen, Phillip J.; Fulton, Benjamin J.; Petigura, Erik A.; Howard, Andrew W.; Hirsch, Lea; Kratter, Kaitlin M.; Crepp, Justin R.; Biller, Beth A.; Johnson, Marshall C.; Wittenmyer, Robert A.

2018-04-01

Gl 758 B is a late-T dwarf orbiting a metal-rich Sun-like star at a projected separation of ρ ≈ 1.″6 (25 au). We present four epochs of astrometry of this system with NIRC2 at Keck Observatory spanning 2010 to 2017 together with 630 radial velocities (RVs) of the host star acquired over the past two decades from McDonald Observatory, Keck Observatory, and the Automated Planet Finder at Lick Observatory. The RVs reveal that Gl 758 is accelerating with an evolving rate that varies between 2 and 5 m s‑1 yr‑1, consistent with the expected influence of the imaged companion Gl 758 B. A joint fit of the RVs and astrometry yields a dynamical mass of {42}-7+19 M Jup for the companion with a robust lower limit of 30.5 M Jup at the 4-σ level. Gl 758 B is on an eccentric orbit (e = 0.26–0.67 at 95% confidence) with a semimajor axis of a = {21.1}-1.3+2.7 au and an orbital period of P = {96}-9+21 yr, which takes it within ≈9 au from its host star at periastron passage. Substellar evolutionary models generally underpredict the mass of Gl 758 B for nominal ages of 1–6 Gyr that have previously been adopted for the host star. This discrepancy can be reconciled if the system is older—which is consistent with activity indicators and recent isochrone fitting of the host star—or alternatively if the models are systematically overluminous by ≈0.1–0.2 dex. Gl 758 B is currently the lowest-mass directly imaged companion inducing a measured acceleration on its host star. In the future, bridging RVs and high-contrast imaging with the next generation of extremely large telescopes and space-based facilities will open the door to the first dynamical mass measurements of imaged exoplanets. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Coronagraphic Imaging with HST and STIS

NASA Technical Reports Server (NTRS)

Grady, C. A.; Proffitt, C.; Malumuth, E.; Woodgate, B. E.; Gull, T. R.; Bowers, C. W.; Heap, S. R.; Kimble, R. A.; Lindler, D.; Plait, P.

2002-01-01

Revealing faint circumstellar nebulosity and faint stellar or substellar companions to bright stars typically requires use of techniques for rejecting the direct, scattered, and diffracted light of the star. One such technique is Lyot coronagraphy. We summarize the performance of the white-light coronagraphic capability of the Space Telescope Imaging spectrograph, on board the Hubble Space Telescope.

T dwarfs all the way to 550 K?

NASA Astrophysics Data System (ADS)

Burningham, Ben; Pinfield, D. J.; Leggett, S. K.; Tamura, M.; Lucas, P. W.; Homeier, D.

2009-02-01

We highlight recent results from the UKIDSS Large Area Survey (LAS) including a T dwarf with an estimated Teff = 550-600 K and new constraints on the substellar mass function in the field. We also define the T9 subtype as an extension to the T spectral sequence defined by Burgasser et al. (2006).

Convective dynamics and chemical disequilibrium in the atmospheres of substellar objects

NASA Astrophysics Data System (ADS)

Bordwell, Baylee; Brown, Benjamin P.; Oishi, Jeffrey S.

2017-11-01

The thousands of substellar objects now known provide a unique opportunity to test our understanding of atmospheric dynamics across a range of environments. The chemical timescales of certain species transition from being much shorter than the dynamical timescales to being much longer than them at a point in the atmosphere known as the quench point. This transition leads to a state of dynamical disequilibrium, the effects of which can be used to probe the atmospheric dynamics of these objects. Unfortunately, due to computational constraints, models that inform the interpretation of these observations are run at dynamical parameters which are far from realistic values. In this study, we explore the behavior of a disequilibrium chemical process with increasingly realistic planetary conditions, to quantify the effects of the approximations used in current models. We simulate convection in 2-D, plane-parallel, polytropically-stratified atmospheres, into which we add reactive passive tracers that explore disequilibrium behavior. We find that as we increase the Rayleigh number, and thus achieve more realistic planetary conditions, the behavior of these tracers does not conform to the classical predictions of disequilibrium chemistry.

Astrophysics of brown dwarfs; Proceedings of the Workshop, George Mason University, Fairfax, VA, Oct. 14, 15, 1985

NASA Technical Reports Server (NTRS)

Kafatos, Minas C. (Editor); Harrington, Robert S. (Editor); Maran, Stephen P. (Editor)

1986-01-01

Various reports on theoretical and observational studies of brown dwarfs (BDs) are presented. The topics considered include: astrometric detection of BDs, search for substellar companions to nearby stars using IR imaging, constraints on BD mass function from optical and IR searches, properties of stellar objects near the main sequence mass limit, search for low-mass stellar companions with the HF precision velocity technique, dynamical search for substellar objects, search for BDs in the IRAS data base, deep CCD survey for low mass stars in the disk and halo, the Berkeley search for a faint solar companion, the luminosity function for late M stars, astronomic search for IR dwarfs, and the role of the Space Telescope in the detection of BDs. Also addressed are: theoretical significance of BDs, evolution of super-Jupiters, compositional indicators in IR spectra of BDs, evolution of BDs and the evolutionary status of VB8B, the position of BDs on universal diagrams, theoretical determination of the minimum protostellar mass, Population II BDs and dark halos.

Mid infrared observations of Van Maanen 2: no substellar companion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farihi, J; Becklin, E; Macintosh, B

2004-11-03

The results of a comprehensive infrared imaging search for the putative 0.06 M{sub {circle_dot}} astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 {micro}m reveal a diffraction limited core of 0.09 inch and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50 M{sub J} brown dwarf would be only 1 magnitude fainter than van Maanen 2 at this wavelength and the astrometric analysis suggested a separation of 0.2 inch. In the case of a chance alignment along the line of sight, a 0.4 mag excessmore » should be measured. An independent photometric observation at the same wavelength reveals no excess. In addition, there exist published ISO observations of van Maanen 2 at 6.8 {micro}m and 15.0 {micro}m which are consistent with photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are correct, there is no substellar companion with T{sub eff} {approx}> 500 K.« less

Dwarfs on a Low-Carbon Diet: Modelling the Chemically Peculiar Secondaries of CVs

NASA Astrophysics Data System (ADS)

Homeier, D.; Harrison, T. E.; Barman, T. S.; Howell, S. B.

2003-12-01

Secondary stars of cataclysmic variables show a variety of abundance anomalies that might be caused by deposition of CNO-processed material. We have calculated PHOENIX stellar atmosphere models for late-type stellar and substellar companions using chemical equilibrium compositions for a range of carbon-depleted and/or oxygen-enriched elemental abundances. We present comparisons of our models with medium-resolution IR spectra of CV secondaries, including the possibly substellar secondary of the EF Eridani system. LTE models of the K-band spectrum are consistent with a Teff in the brown dwarf range and show that the complete lack of CH4 and CO absorption features in this object requires a [C/Fe] ratio more than 2 dex below the solar value. We compare our models to temperature estimates from light curve analyses and present a first irradiated model of the secondary, that takes into account the effect of the impinging flux from the white dwarf primary. This project has been supported by grants from the National Science Foundation and the NASA NStars program.

The Mass-Luminosity Relation in the L/T Transition: Individual Dynamical Masses for the New J-band Flux Reversal Binary SDSSJ105213.51+442255.7AB

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.; Liu, Michael C.; Leggett, S. K.; Ireland, Michael J.; Chiu, Kuenley; Golimowski, David A.

2015-05-01

We have discovered that SDSS J105213.51+442255.7 (T0.5 ± 1.0) is a binary in Keck laser guide star adaptive optics imaging, displaying a large J- to K-band flux reversal ({Δ }J=-0.45+/- 0.09 mag, {Δ }K=0.52+/- 0.05 mag). We determine a total dynamical mass from Keck orbital monitoring (88 ± 5 {{M}Jup}) and a mass ratio by measuring the photocenter orbit from CFHT/WIRCam absolute astrometry ({{M}B}/{{M}A}=0.78+/- 0.07). Combining these provides the first individual dynamical masses for any field L or T dwarfs, 49 ± 3 {{M}Jup} for the L6.5±1.5 primary and 39 ± 3 {{M}Jup} for the T1.5±1.0 secondary. Such a low mass ratio for a nearly equal luminosity binary implies a shallow mass-luminosity relation over the L/T transition ({Δ }log {{L}bol}/{Δ }log M=0.6-0.8+0.6). This provides the first observational support that cloud dispersal plays a significant role in the luminosity evolution of substellar objects. Fully cloudy models fail our coevality test for this binary, giving ages for the two components that disagree by 0.2 dex (2.0σ). In contrast, our observed masses and luminosities can be reproduced at a single age by “hybrid” evolutionary tracks where a smooth change from a cloudy to cloudless photosphere around 1300 K causes slowing of luminosity evolution. Remarkably, such models also match our observed JHK flux ratios and colors well. Overall, it seems that the distinguishing features SDSS J1052+4422AB, like a J-band flux reversal and high-amplitude variability, are normal for a field L/T binary caught during the process of cloud dispersal, given that the age (1.11-0.20+0.17 Gyr) and surface gravity (log g = 5.0-5.2) of SDSS J1052+4422AB are typical for field ultracool dwarfs. Based on data obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, at the Canada-France-Hawaii Telescope, which is operated by the National Research Council of Canada, the Institute National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

V773 Cas, QS Aql, AND BR Ind: ECLIPSING BINARIES AS PARTS OF MULTIPLE SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zasche, P.; Juryšek, J.; Nemravová, J.

2017-01-01

Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similarmore » G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit.« less

Constraining Substellar Magnetic Dynamos using Brown Dwarf Radio Aurorae

NASA Astrophysics Data System (ADS)

Kao, Melodie Minyu

Brown dwarfs share characteristics with both low-mass stars and gas giant planets, making them useful laboratories for studying physics occurring in objects throughout this low mass and temperature range. Of particular interest in this dissertation is the nature of the engine driving their magnetic fields. Fully convective magnetic dynamos can operate in low mass stars, brown dwarfs, gas giant planets, and even fluid metal cores in small rocky planets. Objects in this wide mass range are capable of hosting strong magnetic fields, which shape much of the evolution of planets and stars: strong fields can protect planetary atmospheres from evaporating, generate optical and infrared emission that masquerade as clouds in the atmospheres of other worlds, and affect planet formation mechanisms. Thus, implications from understanding convective dynamo mechanisms also extend to exoplanet habitability. How the convective dynamos driving these fields operate remains an important open problem. While we have extensive data to inform models of magnetic dynamo mechanisms in higher mass stars like our Sun, the coolest and lowest-mass objects that probe the substellar-planetary boundary do not possess the internal structures necessary to drive solar-type dynamos. A number of models examining fully convective dynamo mechanisms have been proposed but they remain unconstrained by magnetic field measurements in the lowest end of the substellar mass and temperature space. Detections of highly circularly polarized pulsed radio emission provide our only window into magnetic field measurements for objects in the ultracool brown dwarf regime, but these detections are very rare; until this dissertation, only one attempt out of 60 had been successful. The work presented in this dissertation seeks to address this problem and examines radio emission from late L, T, and Y spectral type brown dwarfs spanning 1-6 times the surface temperature of Earth and explores implications for fully convective magnetic dynamo models.

Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin–orbit interactions: Prediction of spin–orbit coupling and on-site energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patra, Moumita; Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in

In the present work we investigate the behavior of all three components of persistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba and Dresselhaus spin–orbit interactions. Analogous to persistent charge current in a conducting ring where electrons gain a Berry phase in presence of magnetic flux, spin Berry phase is associated during the motion of electrons in presence of a spin–orbit field which is responsible for the generation of spin current. The interplay between two spin–orbit fields along with quasi-periodic Fibonacci sequence on persistent spin current is described elaborately, and from our analysis, we can estimate the strengthmore » of any one of two spin–orbit couplings together with on-site energy, provided the other is known. - Highlights: • Determination of Rashba and Dresselhaus spin–orbit fields is discussed. • Characteristics of all three components of spin current are explored. • Possibility of estimating on-site energy is given. • Results can be generalized to any lattice models.« less

The TWA 3 Young Triple System: Orbits, Disks, Evolution

NASA Astrophysics Data System (ADS)

Kellogg, Kendra; Prato, L.; Torres, Guillermo; Schaefer, G. H.; Avilez, I.; Ruíz-Rodríguez, D.; Wasserman, L. H.; Bonanos, Alceste Z.; Guenther, E. W.; Neuhäuser, R.; Levine, S. E.; Bosh, A. S.; Morzinski, Katie M.; Close, Laird; Bailey, Vanessa; Hinz, Phil; Males, Jared R.

2017-08-01

We have characterized the spectroscopic orbit of the TWA 3A binary and provide preliminary families of probable solutions for the TWA 3A visual orbit, as well as for the wide TWA 3A-B orbit. TWA 3 is a hierarchical triple located at 34 pc in the ˜10 Myr old TW Hya association. The wide component separation is 1.″55 the close pair was first identified as a possible binary almost 20 years ago. We initially identified the 35-day period orbital solution using high-resolution infrared spectroscopy that angularly resolved the A and B components. We then refined the preliminary orbit by combining the infrared data with a reanalysis of our high-resolution optical spectroscopy. The orbital period from the combined spectroscopic solution is ˜35 days, the eccentricity is ˜0.63, and the mass ratio is ˜0.84 although this high mass ratio would suggest that optical spectroscopy alone should be sufficient to identify the orbital solution, the presence of the tertiary B component likely introduced confusion in the blended optical spectra. Using millimeter imaging from the literature, we also estimate the inclinations of the stellar orbital planes with respect to the TWA 3A circumbinary disk inclination and find that all three planes are likely misaligned by at least ˜30°. The TWA 3A spectroscopic binary components have spectral types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as a triple, is bound, and that its properties were shaped by dynamical interactions between the inclined orbits and disk.

The TWA 3 Young Triple System: Orbits, Disks, Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kellogg, Kendra; Prato, L.; Avilez, I.

2017-08-01

We have characterized the spectroscopic orbit of the TWA 3A binary and provide preliminary families of probable solutions for the TWA 3A visual orbit, as well as for the wide TWA 3A–B orbit. TWA 3 is a hierarchical triple located at 34 pc in the ∼10 Myr old TW Hya association. The wide component separation is 1.″55; the close pair was first identified as a possible binary almost 20 years ago. We initially identified the 35-day period orbital solution using high-resolution infrared spectroscopy that angularly resolved the A and B components. We then refined the preliminary orbit by combining themore » infrared data with a reanalysis of our high-resolution optical spectroscopy. The orbital period from the combined spectroscopic solution is ∼35 days, the eccentricity is ∼0.63, and the mass ratio is ∼0.84; although this high mass ratio would suggest that optical spectroscopy alone should be sufficient to identify the orbital solution, the presence of the tertiary B component likely introduced confusion in the blended optical spectra. Using millimeter imaging from the literature, we also estimate the inclinations of the stellar orbital planes with respect to the TWA 3A circumbinary disk inclination and find that all three planes are likely misaligned by at least ∼30°. The TWA 3A spectroscopic binary components have spectral types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as a triple, is bound, and that its properties were shaped by dynamical interactions between the inclined orbits and disk.« less

The performance of components in the Skylab refrigeration system

NASA Technical Reports Server (NTRS)

Daniher, C. E., Jr.

1975-01-01

The on-orbit performance of the Skylab refrigeration system components is presented. Flight anomalies are analyzed and performance of the newly developed components is described. Nine months of orbit data proved the practicality of the leak-free coolant system design. Flight proven application of a thermal capacitor and development test results of the first all-mechanical, low temperature mixing valve represent a significant advance in single-phase, low temperature coolant loop design. System flight data suggest that additional instrumentation and fluid filters could have prevented system orbit performance anomalies.

V342 Andromedae B is an eccentric-orbit eclipsing binary

NASA Astrophysics Data System (ADS)

Dimitrov, W.; Kamiński, K.; Lehmann, H.; Ligęza, P.; Fagas, M.; Bagińska, P.; Kwiatkowski, T.; Bąkowska, K.; Kowalczyk, A.; Polińska, M.; Bartczak, P.; Przybyszewska, A.; Kruszewski, A.; Kurzawa, K.; Schwarzenberg-Czerny, A.

2015-03-01

We present a photometric and spectroscopic study of the visual binary V342 Andromedae. Visual components of the system have angular separations of 3 arcseconds. We obtained two spectroscopic data sets. An examination of both the A and B component spectra reveals that the B component is a spectroscopic binary with an eccentric orbit. The orbital period, taken from the Hipparcos Catalog, agrees with the orbital period of the B component measured spectroscopically. We also collected a new set of photometric measurements. The argument of periastron is close to 270° and the orbit eccentricity is not seen in our photometric data. About five years after the first spectroscopic observations, a new set of spectroscopic data was obtained. We analysed the apsidal motion, but we did not find any significant changes in the orbital orientation. A Wilson-Devinney model was calculated based on the photometric and the radial velocity curves. The result shows two very similar stars with masses M1 = 1.27 ± 0.01 M⊙, M2 = 1.28 ± 0.01 M⊙, respectively. The radii are R1 = 1.21 ± 0.01 R⊙, R2 = 1.25 ± 0.01 R⊙, respectively. Radial velocity measurements of component A, the most luminous star in the system, reveal no significant periodic variations. We calculated the time of the eclipsing binary orbit's circularization, which is about two orders of magnitude shorter than the estimated age of the system. The discrepancies in the age estimation can be explained by the Kozai effect induced by the visual component A. The atmospheric parameters and the chemical abundances for the eclipsing pair, as well as the LSD profiles for both visual components, were calculated from two high-resolution, well-exposed spectra obtained on the 2-m class telescope. Based on spectroscopy obtained at the David Dunlap Observatory, University of Toronto, Canada, Poznań Spectroscopic Telescope 1, Poland and Thüringer Landessternwarte, Tautenburg, Germany.

Baryonic dark matter

NASA Technical Reports Server (NTRS)

Silk, Joseph

1991-01-01

Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

Analytical energy gradient for the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Zou, Wenli; Filatov, Michael; Cremer, Dieter

2015-06-01

The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown that bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg2 and Cn2, which are due to the admixture of more bonding character to the highest occupied spinors.

The UKIRT Infrared Deep Sky Survey (UKIDSS)

NASA Astrophysics Data System (ADS)

Lawrence, A.; Warren, S. J.; Almaini, O.; Edge, A. C.; Hambly, N. C.; Jameson, R. F.; Lucas, P.; Casali, M.; Adamson, A.; Dye, S.; Emerson, J. P.; Foucaud, S.; Hewett, P.; Hirst, P.; Hodgkin, S. T.; Irwin, M. J.; Lodieu, N.; McMahon, R. G.; Simpson, C.; Smail, I.; Mortlock, D.; Folger, M.

2007-08-01

We describe the goals, design, implementation, and initial progress of the UKIRT Infrared Deep Sky Survey (UKIDSS), a seven-year sky survey which began in 2005 May. UKIDSS is being carried out using the UKIRT Wide Field Camera (WFCAM), which has the largest étendue of any infrared astronomical instrument to date. It is a portfolio of five survey components covering various combinations of the filter set ZYJHK and H2. The Large Area Survey, the Galactic Clusters Survey, and the Galactic Plane Survey cover approximately 7000deg2 to a depth of K ~ 18; the Deep Extragalactic Survey covers 35deg2 to K ~ 21, and the Ultra Deep Survey covers 0.77deg2 to K ~ 23. Summed together UKIDSS is 12 times larger in effective volume than the 2MASS survey. The prime aim of UKIDSS is to provide a long-term astronomical legacy data base; the design is, however, driven by a series of specific goals - for example, to find the nearest and faintest substellar objects, to discover Population II brown dwarfs, if they exist, to determine the substellar mass function, to break the z = 7 quasar barrier; to determine the epoch of re-ionization, to measure the growth of structure from z = 3 to the present day, to determine the epoch of spheroid formation, and to map the Milky Way through the dust, to several kpc. The survey data are being uniformly processed. Images and catalogues are being made available through a fully queryable user interface - the WFCAM Science Archive (http://surveys.roe.ac.uk/wsa). The data are being released in stages. The data are immediately public to astronomers in all ESO member states, and available to the world after 18 months. Before the formal survey began, UKIRT and the UKIDSS consortia collaborated in obtaining and analysing a series of small science verification (SV) projects to complete the commissioning of the camera. We show some results from these SV projects in order to demonstrate the likely power of the eventual complete survey. Finally, using the data from the First Data Release, we assess how well UKIDSS is meeting its design targets so far.

New neighbours. III. 21 new companions to nearby dwarfs, discovered with adaptive optics

NASA Astrophysics Data System (ADS)

Beuzit, J.-L.; Ségransan, D.; Forveille, T.; Udry, S.; Delfosse, X.; Mayor, M.; Perrier, C.; Hainaut, M.-C.; Roddier, C.; Roddier, F.; Martín, E. L.

2004-10-01

We present some results of a CFHT adaptive optics search for companions to nearby dwarfs. We identify 21 new components in solar neighbourhood systems, of which 13 were found while surveying a volume-limited sample of M dwarfs within 12 pc. We are obtaining complete observations for this subsample, to derive unbiased multiplicity statistics for the very-low-mass disk population. Additionally, we resolve for the first time 6 known spectroscopic or astrometric binaries, for a total of 27 newly resolved companions. A significant fraction of the new binaries has favourable parameters for accurate mass determinations. The newly resolved companion of Gl 120.1C was thought to have a spectroscopic minimum mass in the brown-dwarf range (Duquennoy & Mayor \\cite{duquennoy91}), and it contributed to the statistical evidence that a few percent of solar-type stars might have close-in brown-dwarf companions. We find that Gl 120.1C actually is an unrecognised double-lined spectroscopic pair. Its radial-velocity amplitude had therefore been strongly underestimated by Duquennoy & Mayor (\\cite{duquennoy91}), and it does not truly belong to their sample of single-lined systems with minimum spectroscopic mass below the substellar limit. We also present the first direct detection of Gl 494B, an astrometric brown-dwarf candidate. Its luminosity straddles the substellar limit, and it is a brown dwarf if its age is less than ˜300 Myr. A few more years of observations will ascertain its mass and status from first principles. Based on observations made at Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Benchmark cool companions: ages and abundances for the PZ Telescopii system

NASA Astrophysics Data System (ADS)

Jenkins, J. S.; Pavlenko, Y. V.; Ivanyuk, O.; Gallardo, J.; Jones, M. I.; Day-Jones, A. C.; Jones, H. R. A.; Ruiz, M. T.; Pinfield, D. J.; Yakovina, L.

2012-03-01

We present new ages and abundance measurements for the pre-main-sequence star PZ Telescopii (more commonly known as PZ Tel). PZ Tel was recently found to host a young and low-mass companion. Such companions, whether they are brown dwarfs or planetary systems, can attain benchmark status by detailed study of the properties of the primary, and then evolutionary and bulk characteristics can be inferred for the companion. Using Fibre-fed Extended Range Optical Spectrograph spectra, we have measured atomic abundances (e.g. Fe and Li) and chromospheric activity for PZ Tel and used these to obtain the metallicity and age estimates for the companion. We have also determined the age independently using the latest evolutionary models. We find PZ Tel A to be a rapidly rotating (v sin i= 73 ± 5 km s-1), approximately solar metallicity star [log N(Fe) =-4.37 ± 0.06 dex or [Fe/H] = 0.05 ± 0.20 dex]. We measure a non-local thermodynamic equilibrium lithium abundance of log N(Li) = 3.1 ± 0.1 dex, which from depletion models gives rise to an age of 7? Myr for the system. Our measured chromospheric activity (? of -4.12) returns an age of 26 ± 2 Myr, as does fitting pre-main-sequence evolutionary tracks (τevol= 22 ± 3 Myr), both of these are in disagreement with the lithium age. We speculate on reasons for this difference and introduce new models for lithium depletion that incorporate both rotation and magnetic field effects. We also synthesize solar, metal-poor and metal-rich substellar evolutionary models to better determine the bulk properties of PZ Tel B, showing that PZ Tel B is probably more massive than previous estimates, meaning the companion is not a giant exoplanet, even though a planetary-like formation origin can go some way to describing the distribution of benchmark binaries currently known. We show how PZ Tel B compares to other currently known age and metallicity benchmark systems and try to empirically test the effects of dust opacity as a function of metallicity on the near-infrared colours of brown dwarfs. Current models suggest that in the near-infrared observations are more sensitive to low-mass companions orbiting more metal rich stars. We also look for trends between infrared photometry and metallicity amongst a growing population of substellar benchmark objects, and identify the need for more data in mass-age-metallicity parameter space.

NEW EXTINCTION AND MASS ESTIMATES FROM OPTICAL PHOTOMETRY OF THE VERY LOW MASS BROWN DWARF COMPANION CT CHAMAELEONTIS B WITH THE MAGELLAN AO SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ya-Lin; Close, Laird M.; Males, Jared R.

We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and Y{sub S}. With our new photometry and T {sub eff} ∼ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has A{sub V} = 3.4 ± 1.1 mag, and a mass of 14-24 M{sub J} according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates thatmore » the companion has significant Hα emission and a mass accretion rate ∼6 × 10{sup –10} M {sub ☉} yr{sup –1}, similar to some substellar companions. Proper motion analysis shows that another point source within 2'' of CT Cha A is not physical. This paper demonstrates how visible wavelength adaptive optics photometry (r', i', z', Y{sub S}) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions.« less

The Class of Jsolated Stars and Luminous Planetary Nebulae in old stellar populations

NASA Astrophysics Data System (ADS)

Sabach, Efrat; Soker, Noam

2018-06-01

We suggest that stars whose angular momentum (J) does not increase by a companion, star or planet, along their post-main sequence evolution have much lower mass loss rates along their giant branches. Their classification to a separate group can bring insight on their late evolution stages. We here term these Jsolated stars. We argue that the mass loss rate of Jsolated stars is poorly determined because the mass loss rate expressions on the giant branches are empirically based on samples containing stars that experience strong binary interaction, with stellar or sub-stellar companions, e.g., planetary nebula (PN) progenitors. We use our earlier claim for a low mass loss rate of asymptotic giant branch (AGB) stars that are not spun-up by a stellar or substellar companion to show that we can account for the enigmatic finding that the brightest PNe in old stellar populations reach the same luminosity as the brightest PNe in young populations. It is quite likely that the best solution to the existence of bright PNe in old stellar populations is the combination of higher AGB luminosities, as obtained in some new stellar models, and the lower mass loss rates invoked here.

New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Close, Laird M.; Males, Jared R.; Barman, Travis S.; Morzinski, Katie M.; Follette, Katherine B.; Bailey, Vanessa; Rodigas, Timothy J.; Hinz, Philip; Puglisi, Alfio; Xompero, Marco; Briguglio, Runa

2015-03-01

We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and YS . With our new photometry and T eff ~ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has AV = 3.4 ± 1.1 mag, and a mass of 14-24 MJ according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates that the companion has significant Hα emission and a mass accretion rate ~6 × 10-10 M ⊙ yr-1, similar to some substellar companions. Proper motion analysis shows that another point source within 2'' of CT Cha A is not physical. This paper demonstrates how visible wavelength adaptive optics photometry (r', i', z', YS ) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions. This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

The first X-ray emitting brown dwarf.

NASA Astrophysics Data System (ADS)

Comerón, F.; Neuhäuser, R.; Kaas, A. A.

1998-12-01

The increasing number of brown dwarfs discovered in the last few years is rapidly opening the possibilities of studying a wide range of their properties and the ways in which these depend on essential parameters, such as the mass, the age, the rotation, or the environment. One of these properties is the magnetic field, which in principle should be expected to be important in fully convective objects such as brown dwarfs. The chromospheric X-ray emission, widely observed in M-type dwarfs (Neuhäuser 1997), has its origin in this magnetic activity. As such, it offers an observational tool to probe the interior of these objects, the mechanisms for the generation and maintenance of their magnetic fields, and the way in which the magnetic activity is affected by the basic parameters of the object. The detection of X-ray emission from brown dwarfs is thus of great importance to extend our understanding of the properties of stellar magnetic fields to the substellar domain, as well as to ascertain to what extent a small, substellar mass, and the consequent lack of a permanent nuclear energy source, can have an impact in the production and the evolution of a magnetic field.

ORBITS OF FOUR YOUNG TRIPLE-LINED MULTIPLE SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei, E-mail: atokovinin@ctio.noao.edu

2016-07-01

Each of the nearby triple systems HIP 7601, 13498, 23824, and 113597 (HD 10800, 18198, 35877, 217379) consist of solar-type dwarfs with comparable masses, where all three components are resolved spectrally, while the outer pairs are resolved both visually and spectrally. These stars are relatively young (between 100 and 600 Myr) and chromospherically active (X-ray sources), although they rotate slowly. I determine the spectroscopic orbits of the inner subsystems (periods 19.4, 14.1, 5.6, 20.3 days) and the orbits of the outer systems (periods 1.75, 51, 27, 500 years, respectively). For HIP 7601 and 13498, the combined spectro-interferometric outer orbits producemore » direct measurement of the masses of all of the components, allowing for a comparison with stellar models. The 6708 Å lithium line is present and its strength is measured in each component individually by subtracting the contributions of the other components. The inner and outer orbits of HIP 7601 are nearly circular, likely co-planar, and have a modest period ratio of 1:33. This study contributes to the characterization of hierarchical multiplicity in the solar neighborhood and provides data for testing stellar evolutionary models and chronology.« less

NEW PRECISION ORBITS OF BRIGHT DOUBLE-LINED SPECTROSCOPIC BINARIES. V. THE AM STARS HD 434 AND 41 SEXTANTIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fekel, Francis C.; Williamson, Michael H., E-mail: fekel@evans.tsuniv.ed

We have detected the secondary component in two previously known spectroscopic binaries, HD 434 and 41 Sex, and for the first time determined double-lined orbits for them. Despite the relatively long period of 34.26 days and a moderate eccentricity of 0.32, combined with the components' rotationally broadened lines, measurement of the primary and secondary radial velocities of HD 434 has enabled us to obtain significantly improved orbital elements. While the 41 Sex system has a much shorter period of 6.167 days and a circular orbit, the estimated V mag difference of 3.2 between its components also makes this a challengingmore » system. The new orbital dimensions (a{sub 1} sin i and a{sub 2} sin i) and minimum masses (m{sub 1} sin{sup 3} i and m{sub 2} sin{sup 3} i) of HD 434 have accuracies of 0.8% or better, while the same quantities for 41 Sex are good to 0.5% or better. Both components of HD 434 are Am stars while the Am star primary of 41 Sex has a late-F or early-G companion. All four stars are on the main sequence. The two components of HD 434 are rotating much faster than their predicted pseudosynchronous velocities, while both components of 41 Sex are synchronously rotating. For the primary of 41 Sex, the spectrum line depth changes noted by Sreedhar Rao et al. were not detected.« less

Space shuttle phase B wind tunnel model and test information. Volume 2: Orbiter configuration

NASA Technical Reports Server (NTRS)

Glynn, J. L.; Poucher, D. E.

1988-01-01

Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a data base and are available for applying to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Data Base is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retro-glide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configuration types include booster and orbiter components in various stacked and tandem combinations.

A Representative Shuttle Environmental Control System

NASA Technical Reports Server (NTRS)

Brose, H. F.; Stanley, M. D.; Leblanc, J. C.

1977-01-01

The Representative Shuttle Environmental Control System (RSECS) provides a ground test bed to be used in the early accumulation of component and system operating data, the evaluation of potential system improvements, and possibly the analysis of Shuttle Orbiter test and flight anomalies. Selected components are being subjected to long term tests to determine endurance and corrosion resistance capability prior to Orbiter vehicle experience. Component and system level tests in several cases are being used to support flight certification of Orbiter hardware. These activities are conducted as a development program to allow for timeliness, flexibility, and cost effectiveness not possible in a program burdened by flight documentation and monitoring constraints.

Composite material application for liquid rocket engines

NASA Technical Reports Server (NTRS)

Heubner, S. W.

1982-01-01

With increasing emphasis on improving engine thrust-to-weight ratios to provide improved payload capabilities, weight reductions achievable by the use of composites have become attractive. Of primary significance is the weight reduction offered by composites, although high temperature properties and cost reduction were also considered. The potential for application of composites to components of Earth-to-orbit hydrocarbon engines and orbit-to-orbit LOX/H2 engines was assessed. The components most likely to benefit from the application of composites were identified, as were the critical technology areas where developed would be required. Recommendations were made and a program outlined for the design, fabrication, and demonstration of specific engine components.

IC 5181: An S0 Galaxy with Ionized Gas on Polar Orbits

NASA Astrophysics Data System (ADS)

Pizzella, A.; Morelli, L.; Corsini, E. M.; Dalla Bontá, E.; Cesetti, M.

2014-05-01

The nearby S0 galaxy IC 5181 is studied to address the origin of the ionized gas component that orbits the galaxy on polar orbit. We perform detailed photometric and spectroscopic observations measuring the surface brightness distribution of the stars (I band), ionized gas of IC 5181 (Hα narrow band), the ionized-gas and stellar kinematics along both the major and minor axis, and the corresponding line strengths of the Lick indices. We conclude that the galaxy hosts a geometrically and kinematically decoupled component of ionized gas. It is elongated along the galaxy minor axis and in orthogonal rotation with respect to the galaxy disk. The result is suggesting that the gas component is not related to the stars having an external origin. The gas was accreted by IC 5181 on polar orbits from the surrounding environment.

Analytical energy gradient for the two-component normalized elimination of the small component method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Wenli; Filatov, Michael; Cremer, Dieter, E-mail: dcremer@smu.edu

2015-06-07

The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown thatmore » bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg{sub 2} and Cn{sub 2}, which are due to the admixture of more bonding character to the highest occupied spinors.« less

STRONG DEPENDENCE OF THE INNER EDGE OF THE HABITABLE ZONE ON PLANETARY ROTATION RATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jun; Abbot, Dorian S.; Boué, Gwenaël

2014-05-20

Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for determining the mean planetary climate. Here we investigate this idea using a three-dimensional general circulation model with a sophisticated cloud scheme. We find that slowly rotating planets (like Venus) can maintain an Earth-like climate at nearly twice the stellar flux as rapidly rotating planets (like Earth). This suggests that many exoplanets previously believed to be too hot may actually be habitable, depending on their rotationmore » rate. The explanation for this behavior is that slowly rotating planets have a weak Coriolis force and long daytime illumination, which promotes strong convergence and convection in the substellar region. This produces a large area of optically thick clouds, which greatly increases the planetary albedo. In contrast, on rapidly rotating planets a much narrower belt of clouds form in the deep tropics, leading to a relatively low albedo. A particularly striking example of the importance of rotation rate suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time.« less

Competition of supermassive black holes and galactic spheroids in the destruction of globular clusters

NASA Technical Reports Server (NTRS)

Charlton, Jane C.; Laguna, Pablo

1995-01-01

The globular clusters that we observe in galaxies may be only a fraction of the initial population. Among the evolutionary influences on the population is the destruction of globular clusters by tidal forces as the cluster moves through the field of influence of a disk, a bulge, and/or a putative nuclear component (black hole). We have conducted a series of N-body simulations of globular clusters on bound and marginally bound orbits through poetentials that include black hole and speroidal components. The degree of concentration of the spheroidal component can have a considerable impact on the extent to which a globular cluster is disrupted. If half the mass of a 10(exp 10) solar mass spheroid is concentrated within 800 pc, then only black holes with masses greater than 10(exp 9) solar mass can have a significant tidal influence over that already exerted by the bulge. However, if the matter in the spheroidal component is not so strongly concentrated toward the center of the galaxy, a more modest central black hole (down to 10(exp 8) solar mass) could have a dominant influence on the globular cluster distribution, particularly if many of the clusters were initially on highly radial orbits. Our simulations show that the stars that are stripped from a globular cluster follow orbits with roughly the same eccentricity as the initial cluster orbit, spreading out along the orbit like a 'string of pearls.' Since only clusters on close to radial orbits will suffer substantial disruption, the population of stripped stars will be on orbits of high eccentricity.

Knowing our neighbors: Fundamental properties of nearby stars

NASA Astrophysics Data System (ADS)

Bartlett, Jennifer Lynn

The stars within 25 parsecs (pc) of our Sun constitute the one stellar sample that we aspire to know thoroughly, but we still have not even identified all of the stars within 10 pc. We have still less knowledge of the nearby substellar population, especially the planets. The four studies described herein expand our knowledge of the solar neighborhood. First, a re-analysis of the Leander McCormick Observatory photographic plates of Barnard's Star failed to detect any planets orbiting it, and this study would have detected planets with 2.2 Jupiter masses or greater. In addition, its parallax, proper motion, and secular acceleration were measured with results comparable with those from more modern equipment. Second, increased information about nearby planets was sought through time series analyses of astrometric residuals to stars observed by the University of Virginia Southern Parallax Program. Of these, LHS 288 displays an intriguing signal, which might be caused by a very low mass companion. Twelve other stars demonstrate no astrometric perturbations. While astrometry could reveal the presence of unseen companions, distances from trigonometric parallaxes define the solar neighborhood and identify its inhabitants. Preliminary parallaxes for 43 potential nearby stars being observed by the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI) confirmed 28 stars as being within 25 pc, including three stars---LP 991-84, LHS 6167, and LP 876-10---that probably lie within 10 pc. Three more stars lie near the 25-pc boundary and their final parallaxes may qualify them as nearby. One recently established neighbor, LP 869-26, is a potential binary. For many stars in this third sample, preliminary photometry ( V, R, and I bands), spectroscopy, and proper motions are also available. Despite the continuing importance of ground-based parallax measurements, few active programs remain. The final project tested the recently installed infrared camera on the 31-inch (0.8-meter) telescope at Fan Mountain Observatory for astrometric stability. A parallax program would be feasible there and could provide much needed distances for brown dwarfs and very low mass stars. Through this and similar efforts, we are establishing the foundations for understanding our Milky Way Galaxy, including its component stars and populations.

Calculations of electric dipole moments and static dipole polarizabilities based on the two-component normalized elimination of the small component method.

PubMed

Yoshizawa, Terutaka; Zou, Wenli; Cremer, Dieter

2016-11-14

The analytical energy gradient and Hessian of the two-component Normalized Elimination of the Small Component (2c-NESC) method with regard to the components of the electric field are derived and used to calculate spin-orbit coupling (SOC) corrected dipole moments and dipole polarizabilities of molecules, which contain elements with high atomic number. Calculated 2c-NESC dipole moments and isotropic polarizabilities agree well with the corresponding four-component-Dirac Hartree-Fock or density functional theory values. SOC corrections for the electrical properties are in general small, but become relevant for the accurate prediction of these properties when the molecules in question contain sixth and/or seventh period elements (e.g., the SO effect for At 2 is about 10% of the 2c-NESC polarizability). The 2c-NESC changes in the electric molecular properties are rationalized in terms of spin-orbit splitting and SOC-induced mixing of frontier orbitals with the same j = l + s quantum numbers.

Calculations of electric dipole moments and static dipole polarizabilities based on the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Yoshizawa, Terutaka; Zou, Wenli; Cremer, Dieter

2016-11-01

The analytical energy gradient and Hessian of the two-component Normalized Elimination of the Small Component (2c-NESC) method with regard to the components of the electric field are derived and used to calculate spin-orbit coupling (SOC) corrected dipole moments and dipole polarizabilities of molecules, which contain elements with high atomic number. Calculated 2c-NESC dipole moments and isotropic polarizabilities agree well with the corresponding four-component-Dirac Hartree-Fock or density functional theory values. SOC corrections for the electrical properties are in general small, but become relevant for the accurate prediction of these properties when the molecules in question contain sixth and/or seventh period elements (e.g., the SO effect for At2 is about 10% of the 2c-NESC polarizability). The 2c-NESC changes in the electric molecular properties are rationalized in terms of spin-orbit splitting and SOC-induced mixing of frontier orbitals with the same j = l + s quantum numbers.

Astronaut tool development: An orbital replaceable unit-portable handhold

NASA Technical Reports Server (NTRS)

Redmon, John W., Jr.

1989-01-01

A tool to be used during astronaut Extra-Vehicular Activity (EVA) replacement of spent or defective electrical/electronic component boxes is described. The generation of requirements and design philosophies are detailed, as well as specifics relating to mechanical development, interface verifications, testing, and astronaut feedback. Findings are presented in the form of: (1) a design which is universally applicable to spacecraft component replacement, and (2) guidelines that the designer of orbital replacement units might incorporate to enhance spacecraft on-orbit maintainability and EVA mission safety.

The spectroscopic orbit of Capella revisited

NASA Astrophysics Data System (ADS)

Weber, M.; Strassmeier, K. G.

2011-07-01

Context. Capella is among the few binary stars with two evolved giant components. The hotter component is a chromospherically active star within the Hertzsprung gap, while the cooler star is possibly helium-core burning. Aims: The known inclination of the orbital plane from astrometry in combination with precise radial velocities will allow very accurate masses to be determined for the individual Capella stars. This will constrain their evolutionary stage and possibly the role of the active star's magnetic field on the dynamical evolution of the binary system. Methods: We obtained a total of 438 high-resolution échelle spectra during the years 2007-2010 and used the measured velocities to recompute the orbital elements. Our double-lined orbital solution yields average residuals of 64 m s-1 for the cool component and 297 m s-1 for the more rapidly rotating hotter component. Results: The semi-amplitude of the cool component is smaller by 0.045 km s-1 than the orbit determination of Torres et al. from data taken during 1996-1999 but more precise by a factor of 5.5, while for the hotter component it is larger by 0.580 km s-1 and more precise by a factor of 3.6. This corresponds to masses of 2.573 ± 0.009 M⊙ and 2.488 ± 0.008 M⊙ for the cool and hot component, respectively. Their relative errors of 0.34% and 0.30% are about half of the values given in Torres et al. for a combined literature-data solution but with absolute values different by 4% and 2% for the two components, respectively. The mass ratio of the system is therefore q = MA/MB = 0.9673 ± 0.0020. Conclusions: Our orbit is the most precise and also likely to be the most accurate ever obtained for Capella. Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC.Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A89

Ground-Based Astrometry 2010-2020

DTIC Science & Technology

2010-01-01

The two most compelling questions to be addressed are (1) What is the composition of the stellar and substellar population near the Sun? and (2) What ...of the intellectual and financial investments made for what some have called “The Decade of Astrometry.” The most important recommendation is to...measurements in astronomy is the trigonometric parallax, which forms the fundamental rung in the astronomical distance ladder. Advances in

Brown dwarfs: at last filling the gap between stars and planets.

PubMed

Zuckerman, B

2000-02-01

Until the mid-1990s a person could not point to any celestial object and say with assurance that "here is a brown dwarf." Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems.

The Impact of Clouds and Hazes in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan J.; Marley, Mark S.

2016-01-01

The formation of clouds significantly alters the spectra of cool substellar atmospheres from terrestrial planets to brown dwarfs. In cool planets like Earth and Jupiter, volatile species like water and ammonia condense to form ice clouds. In hot planets and brown dwarfs, iron and silicates instead condense, forming dusty clouds. Irradiated methane-rich planets may have substantial hydrocarbon hazes. During my thesis, I have studied the impact of clouds and hazes in a variety of substellar objects. First, I present results for cool brown dwarfs including clouds previously neglected in model atmospheres. Model spectra that include sulfide and salt clouds can match the spectra of T dwarf atmospheres; water ice clouds will alter the spectra of the newest and coldest brown dwarfs, the Y dwarfs. These sulfide/salt and ice clouds potentially drive spectroscopic variability in these cool objects, and this variability should be distinguishable from variability caused by hot spots.Next, I present results for small, cool exoplanets between the size of Earth and Neptune, so-called super Earths. They likely have sulfide and salt clouds and also have photochemical hazes caused by stellar irradiation. Vast resources have been dedicated to characterizing the handful of super Earths accessible to current telescopes, yet of the planets smaller than Neptune studied to date, all have radii in the near-infrared consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. Very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. I show that despite these challenges, there are promising avenues for understanding this class of small planets: by observing the thermal emission and reflectivity of small planets, we can break the degeneracies and better constrain the atmospheric compositions. These observations may provide rich diagnostics of molecules and clouds in small planets, in contrast to the limited success to date.

A survey for low-mass stellar and substellar members of the Hyades open cluster

NASA Astrophysics Data System (ADS)

Melnikov, Stanislav; Eislöffel, Jochen

2018-03-01

Context. Unlike young open clusters (with ages < 250 Myr), the Hyades cluster (age 600 Myr) has a clear deficit of very low-mass stars (VLM) and brown dwarfs (BD). Since this open cluster has a low stellar density and covers several tens of square degrees on the sky, extended surveys are required to improve the statistics of the VLM/BD objects in the cluster. Aim. We search for new VLM stars and BD candidates in the Hyades cluster to improve the present-day cluster mass function down to substellar masses. Methods: An imaging survey of the Hyades with a completeness limit of 21.m5 in the R band and 20.m5 in the I band was carried out with the 2k × 2k CCD Schmidt camera at the 2 m Alfred Jensch Telescope in Tautenburg. We performed a photometric selection of the cluster member candidates by combining results of our survey with 2MASS JHKs photometry Results: We present a photometric and proper motion survey covering 23.4 deg2 in the Hyades cluster core region. Using optical/IR colour-magnitude diagrams, we identify 66 photometric cluster member candidates in the magnitude range 14.m7 < I < 20.m5. The proper motion measurements are based on several all-sky surveys with an epoch difference of 60-70 yr for the bright objects. The proper motions allowed us to discriminate the cluster members from field objects and resulted in 14 proper motion members of the Hyades. We rediscover Hy 6 as a proper motion member and classify it as a substellar object candidate (BD) based on the comparison of the observed colour-magnitude diagram with theoretical model isochrones. Conclusions: With our results, the mass function of the Hyades continues to be shallow below 0.15 M⊙ indicating that the Hyades have probably lost their lowest mass members by means of dynamical evolution. We conclude that the Hyades core represents the "VLM/BD desert" and that most of the substeller objects may have already left the volume of the cluster.

A Survey for Circumstellar Disks around Young Substellar Objects

NASA Astrophysics Data System (ADS)

Liu, Michael C.; Najita, Joan; Tokunaga, Alan T.

2003-03-01

We have completed the first systematic survey for disks around spectroscopically identified young brown dwarfs and very low mass stars. For a sample of 38 very cool objects in IC 348 and Taurus, we have obtained L'-band (3.8 μm) imaging with sufficient sensitivity to detect objects with and without disks. The sample should be free of selection biases for our purposes. Our targets span spectral types from M6 to M9.5, corresponding to masses of ~15-100 MJup and ages of <~5 Myr, based on current models. None appear to be binaries at 0.4" resolution (55-120 AU). Using the objects' measured spectral types and extinctions, we find that most of our sample (77%+/-15%) possess intrinsic IR excesses, indicative of circum(sub)stellar disks. Because the excesses are modest, conventional analyses using only IR colors would have missed most of the sources with excesses. Such analyses inevitably underestimate the disk fraction and will be less reliable for young brown dwarfs than for T Tauri stars. The observed IR excesses are correlated with Hα emission, consistent with a common accretion disk origin. In the same star-forming regions, we find that disks around brown dwarfs and T Tauri stars are contemporaneous; assuming coevality, this demonstrates that the inner regions of substellar disks are at least as long-lived as stellar disks and evolve slowly for the first ~3 Myr. The disk frequency appears to be independent of mass. However, some objects in our sample, including the very coolest (lowest mass) ones, lack IR excesses and may be diskless. The observed excesses can be explained by disk reprocessing of starlight alone; the implied accretion rates are at least an order of magnitude below typical values for classical T Tauri stars. The observed distribution of IR excesses suggests inner disk holes with radii of >~2R*, consistent with the idea that such holes arise from disk-magnetosphere interactions. Altogether, the frequency and properties of young circumstellar disks appear to be similar from the stellar regime down to the substellar and planetary-mass regime. This provides prima facie evidence of a common origin for most stars and brown dwarfs.

Orbital engineering of nickelates in three-component heterostructures

NASA Astrophysics Data System (ADS)

Disa, Ankit; Kumah, Divine; Malashevich, Andrei; Chen, Hanghui; Ismail-Beigi, Sohrab; Walker, Fred; Ahn, Charles; Specht, Eliot; Arena, Dario

2015-03-01

The orbital configuration of complex oxides dictates the emergence of a wide range of properties, including metal-insulator transitions, interfacial magnetism, and high-temperature superconductivity. In this work, we experimentally demonstrate a novel method for achieving large and tunable orbital polarizations in nickelates. The technique is based on leveraging three-component, atomically layered superlattices to yield a combination of inversion symmetry breaking, charge transfer, and polar distortions. In the system we studied, composed of LaTiO3/LaNiO3/LaAlO3, we use synchrotron x-ray diffraction and spectroscopy to characterize these properties and show that they lead to fully broken orbital degeneracy in the nickelate layer consistent with a single-band Fermi surface. Furthermore, we show that this system is widely tunable and enables quasi-continuous orbital control unachievable by conventional strain and confinement-based approaches. This technique provides an experimentally realizable route for accessing and studying novel orbitally dependent quantum phenomena.

The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes

NASA Technical Reports Server (NTRS)

Armstrong, J. T.; Hummel, C. A.; Quirrenbach, A.; Buscher, D. F.; Mozurkewich, D.; Vivekanand, M.; Simon, R. S.; Denison, C. S.; Johnston, K. J.; Pan, X.-P.

1992-01-01

The orbit of the double-lined spectroscopic binary Phi Cygni, the distance to the system, and the masses and absolute magnitudes of its components are presented via measurements with the Mar III Optical Interferometer. On the basis of a reexamination of the spectroscopic data of Rach & Herbig (1961), the values and uncertainties are adopted for the period and the projected semimajor axes from the present fit to the spectroscopic data and the values of the remaining elements from the present fit to the Mark III data. The elements of the true orbit are derived, and the masses and absolute magnitudes of the components, and the distance to the system are calculated.

A Search for Planets and Brown Dwarfs around Post Main Sequence Stars

NASA Astrophysics Data System (ADS)

Otani, Tomomi; Oswalt, Terry D.

2016-06-01

The most promising current theory for the origin of subdwarf B (sdB) stars is that they were formed during binary star evolution. This project was conducted to test this hypothesis by searching for companions around six sdB pulsators using the Observed-minus-Calculated (O-C) method. A star’s position in space will wobble due to the gravitational forces of any companion. If it is emitting a periodic signal, the orbital motion of the star around the system’s center of mass causes periodic changes in the light pulse arrival times. O-C diagrams for six sdB pulsators were constructed from several years’ observations, providing useful limits on suspected companions’ minimum masses and semimajor axes. The results were constrained by “period vs. amplitude” and “mass vs. semimajor axis” models to quantify companion masses and semimajor axes that are consistent with the observational data, if any. Two of our targets, V391 Peg and HS0702+6043, are noted in previous publications to have substellar companions. These were used to validate the method used in this research. The results of this study yielded the same masses and semimajor axes for these two stars as the published values, within the uncertainties. Another of the targets, EC20117-4014, is noted in the literature as a binary system containing an sdB and F5V star, however the orbital period and separation were unknown. The new data obtained in this study contain the signal of a companion candidate with a period of 158.01 days. Several possible mass and semimajor axis combinations for the companion are consistent with the observations. One of the other targets in this study displayed preliminary evidence for a companion that will require further observation. Though still a small sample, these results suggest that planets often survive the post-main-sequence evolution of their parent stars.

Is orbital volume associated with eyeball and visual cortex volume in humans?

PubMed

Pearce, Eiluned; Bridge, Holly

2013-01-01

In humans orbital volume increases linearly with absolute latitude. Scaling across mammals between visual system components suggests that these larger orbits should translate into larger eyes and visual cortices in high latitude humans. Larger eyes at high latitudes may be required to maintain adequate visual acuity and enhance visual sensitivity under lower light levels. To test the assumption that orbital volume can accurately index eyeball and visual cortex volumes specifically in humans. Structural Magnetic Resonance Imaging (MRI) techniques are employed to measure eye and orbit (n = 88) and brain and visual cortex (n = 99) volumes in living humans. Facial dimensions and foramen magnum area (a proxy for body mass) were also measured. A significant positive linear relationship was found between (i) orbital and eyeball volumes, (ii) eyeball and visual cortex grey matter volumes and (iii) different visual cortical areas, independently of overall brain volume. In humans the components of the visual system scale from orbit to eye to visual cortex volume independently of overall brain size. These findings indicate that orbit volume can index eye and visual cortex volume in humans, suggesting that larger high latitude orbits do translate into larger visual cortices.

Is orbital volume associated with eyeball and visual cortex volume in humans?

PubMed Central

Pearce, Eiluned; Bridge, Holly

2013-01-01

Background In humans orbital volume increases linearly with absolute latitude. Scaling across mammals between visual system components suggests that these larger orbits should translate into larger eyes and visual cortices in high latitude humans. Larger eyes at high latitudes may be required to maintain adequate visual acuity and enhance visual sensitivity under lower light levels. Aim To test the assumption that orbital volume can accurately index eyeball and visual cortex volumes specifically in humans. Subjects & Methods Structural Magnetic Resonance Imaging (MRI) techniques are employed to measure eye and orbit (N=88), and brain and visual cortex (N=99) volumes in living humans. Facial dimensions and foramen magnum area (a proxy for body mass) were also measured. Results A significant positive linear relationship was found between (i) orbital and eyeball volumes, (ii) eyeball and visual cortex grey matter volumes, (iii) different visual cortical areas, independently of overall brain volume. Conclusion In humans the components of the visual system scale from orbit to eye to visual cortex volume independently of overall brain size. These findings indicate that orbit volume can index eye and visual cortex volume in humans, suggesting that larger high latitude orbits do translate into larger visual cortices. PMID:23879766

Pressure loads and aerodynamic force information for the -89A space shuttle orbiter configuration, volume 2

NASA Technical Reports Server (NTRS)

Mennell, R. C.

1973-01-01

Experimental aerodynamic investigations were conducted in a low speed wind tunnel on an 0.0405 scale representation of the 89A light weight Space Shuttle Orbiter to obtain pressure loads data in the presence of the ground for orbiter structural strength analysis. The model and the facility are described, and data reduction is outlined. Tables are included for data set/run number collation, data set/component collation, model component description, and pressure tap locations by series number. Tabulated force and pressure source data are presented.

The Orbit and Distance of WR140

NASA Astrophysics Data System (ADS)

Dougherty, S. M.; Trenton, V.; Beasley, A. J.

2011-01-01

A campaign of 35 epochs of milli-arcsecond resolution VLBA observations of the archetype colliding-wind WR+O star binary system WR 140 show the wind-collision region (WCR) as a bow-shaped arc of emission that rotates as the highly eccentric orbit progresses. The observations comprise 21 epochs from the 1993-2001 orbit, discussed by Dougherty et al. (2005), and 14 epochs from the 2001-2009 orbit, and span orbital phase 0.43 to 0.95. Assuming the WCR is symmetric about the line-of-centres of the two stars and ``points'' at the WR star, this rotation shows the O star moving from SE to E of the WR star between these orbital phases. Using IR interferometry observations from IOTA that resolve both stellar components at phase 0.297 in conjunction with orbital parameters derived from radial velocity variations, the VLBA observations constrain the inclination of the orbit plane as 120°±4°, the longitude of the ascending node as 352°±2°, and the orbit semi-major axis as 9.0±0.1 mas. This leads to a distance estimate to WR 140 of 1.81±0.08 kpc. Further refinements of the orbit and distance await more IR interferometric observations of the stellar components directly.

Meteoroid/Orbital Debris Shield Engineering Development Practice and Procedure

NASA Technical Reports Server (NTRS)

Zwitter, James G.; Adams, Marc A.

2011-01-01

A document describes a series of models created for the determination of the probability of survival of critical spacecraft components from particle strike damage caused by hypervelocity impact of meteoroids and/or orbital debris. These models were integrated with both shield design and hypervelocity impact testing to develop adequate protection of said components to meet mission survivability requirements.

On-orbit spacecraft reliability

NASA Technical Reports Server (NTRS)

Bloomquist, C.; Demars, D.; Graham, W.; Henmi, P.

1978-01-01

Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

Brown dwarfs: At last filling the gap between stars and planets

PubMed Central

Zuckerman, Ben

2000-01-01

Until the mid-1990s a person could not point to any celestial object and say with assurance that “here is a brown dwarf.” Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems. PMID:10655468

Environmental testing to prevent on-orbit TDRS failures

NASA Technical Reports Server (NTRS)

Cutler, Robert M.

1994-01-01

Can improved environmental testing prevent on-orbit component failures such as those experienced in the Tracking and Data Relay Satellite (TDRS) constellation? TDRS communications have been available to user spacecraft continuously for over 11 years, during which the five TDRS's placed in orbit have demonstrated their redundancies and robustness by surviving 26 component failures. Nevertheless, additional environmental testing prior to launch could prevent the occurrence of some types of failures, and could help to maintain communication services. Specific testing challenges involve traveling wave tube assemblies (TWTA's) whose lives may decrease with on-off cycling, and heaters that are subject to thermal cycles. The development of test conditions and procedures should account for known thermal variations. Testing may also have the potential to prevent failures in which components such as diplexers have had their lives dramatically shortened because of particle migration in a weightless environment. Reliability modeling could be used to select additional components that could benefit from special testing, but experience shows that this approach has serious limitations. Through knowledge of on-orbit experience, and with advances in testing, communication satellite programs might avoid the occurrence of some types of failures, and extend future spacecraft longevity beyond the current TDRS design life of ten years. However, determining which components to test, and how must testing to do, remain problematical.

Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Z. H.; Pinfield, D. J.; Gálvez-Ortiz, M. C.; Homeier, D.; Burgasser, A. J.; Lodieu, N.; Martín, E. L.; Osorio, M. R. Zapatero; Allard, F.; Jones, H. R. A.; Smart, R. L.; Martí, B. López; Burningham, B.; Rebolo, R.

2018-05-01

We report the discovery of an esdL3 subdwarf, ULAS J020858.62+020657.0 and a usdL4.5 subdwarf, ULAS J230711.01+014447.1. They were identified as L subdwarfs by optical spectra obtained with the Gran Telescopio Canarias, and followed up by optical to near infrared spectroscopy with the Very Large Telescope. We also obtained an optical to near infrared spectrum of a previously known L subdwarf, ULAS J135058.85+081506.8, and re-classified it as a usdL3 subdwarf. These three objects all have typical halo kinematics. They have Teff around 2050-2250 K, -1.8 ≤ [Fe/H] ≤-1.5, and mass around 0.0822-0.0833 M⊙, according to model spectral fitting and evolutionary models. These sources are likely halo transitional brown dwarfs with unsteady hydrogen fusions, as their masses are just below the hydrogen-burning minimum mass, which is ˜ 0.0845 M⊙ at [Fe/H] = -1.6 and ˜ 0.0855 M⊙ at [Fe/H] = -1.8. Including these, there are now nine objects in the `halo brown dwarf transition zone', which is a `substellar subdwarf gap' spans a wide temperature range within a narrow mass range of the substellar population.

Evidence that the Planetary Candidate CVSO30c is a Background Star from Optical, Seeing-limited Data

NASA Astrophysics Data System (ADS)

Lee, Chien-Hsiu; Chiang, Po-Shih

2018-01-01

We report serendipitous optical imaging of CVSO30c, an exoplanet candidate associated with the pre-main-sequence T Tauri star CVSO30 that resides in the 25 Ori stellar cluster. We perform PSF modeling on our seeing-limited optical image to remove the lights from the host star (CVSO30), allowing us to extract photometry of CVSO30c to be g = 23.2 ± 0.2 (statistic) ± 0.1 (systematic) and r = 21.5 ± 0.1 (statistic) ± 0.1 (systematic) magnitudes, respectively. This is 170 and 80 times too bright in the g and r bands, respectively, if CVSO30c were an L0 substellar object as suggested by previous studies. The optical/infrared colors of CVSO30c are indicative of a stellar, not substellar object, while the object’s color–magnitude diagram position is strikingly inconsistent with expected values for a low-mass member of 25 Ori. Broadband photometry for CVSO30c is instead better fit by contaminants such as a background K3 giant or M subdwarf. Our study demonstrates that optical seeing-limited data can help clarify the nature of candidate wide separation planet-mass companions in young star-forming regions.

Direct imaging of an ultracool substellar companion to the exoplanet host star HD 4113 A

NASA Astrophysics Data System (ADS)

Cheetham, A.; Ségransan, D.; Peretti, S.; Delisle, J.-B.; Hagelberg, J.; Beuzit, J.-L.; Forveille, T.; Marmier, M.; Udry, S.; Wildi, F.

2018-06-01

Using high-contrast imaging with the SPHERE instrument at the Very Large Telescope (VLT), we report the first images of a cold brown dwarf companion to the exoplanet host star HD 4113A. The brown dwarf HD 4113C is part of a complex dynamical system consisting of a giant planet, a stellar host, and a known wide M-dwarf companion. Its separation of 535 ± 3 mas and H-band contrast of 13.35 ± 0.10 mag correspond to a projected separation of 22 AU and an isochronal mass estimate of 36 ± 5 MJ based on COND models. The companion shows strong methane absorption, and through fitting an atmosphere model, we estimate a surface gravity of logg = 5 and an effective temperature of 500-600 K. A comparison of its spectrum with observed T dwarfs indicates a late-T spectral type, with a T9 object providing the best match. By combining the observed astrometry from the imaging data with 27 years of radial velocities, we use orbital fitting to constrain its orbital and physical parameters, as well as update those of the planet HD 4113A b, discovered by previous radial velocity measurements. The data suggest a dynamical mass of 66-4+5 MJ and moderate eccentricity of 0.44-0.07+0.08 for the brown dwarf. This mass estimate appears to contradict the isochronal estimate and that of objects with similar temperatures, which may be caused by the newly detected object being an unresolved binary brown dwarf system or the presence of an additional object in the system. Through dynamical simulations, we show that the planet may undergo strong Lidov-Kozai cycles, raising the possibility that it formed on a quasi-circular orbit and gained its currently observed high eccentricity (e 0.9) through interactions with the brown dwarf. Follow-up observations combining radial velocities, direct imaging, and Gaia astrometry will be crucial to precisely constrain the dynamical mass of the brown dwarf and allow for an in-depth comparison with evolutionary and atmosphere models. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 097.C-0893(A), 077.C-0293(A), 279.C-5052(A), 081.C-0653(A) and 091.C-0721(B).

Orbital period changes in RW CrA, DX Vel and V0646 Cen

NASA Astrophysics Data System (ADS)

Volkov, I. M.; Chochol, D.; Grygar, J.; Mašek, M.; Juryšek, J.

2017-06-01

We aim to determine the absolute parameters of the components of southern Algol-type binaries with deep eclipses RW CrA, DX Vel, V0646 Cen and interpret their orbital period changes. The data analysis is based on a high quality Walraven photoelectric photometry, obtained in the 1960-70s, our recent CCD photometry, ASAS (Pojmanski, 2002), and Hipparcos (Perryman et al., 1997) photometry of the objects. Their light curves were analyzed using the PHOEBE program with fixed effective temperatures of the primary components, found from disentangling the Walraven (B-U) and (V-B) colour indices. We found the absolute parameters of the components of all three objects. All reliable observed times of minimum light were used to construct and analyze the Eclipse Time Variation (ETV) diagrams. We interpreted the ETV diagrams of the detached binary RW CrA and the semi-detached binary DX Vel by a LIght-Time Effect (LITE), estimated parameters of their orbits and masses of their third bodies. We suggest a long term variation of the inclination angle of both eclipsing binaries, caused by a non-coplanar orientation of their third body orbits. We interpreted the detected orbital period increase in the semi-detached binary V0646 Cen by a mass transfer from the less to more massive component with the rate M⊙ = 6.08×10-9 M⊙/yr.

On protection of Freedom's solar dynamic radiator from the orbital debris environment. Part 1: Preliminary analyses and testing

NASA Technical Reports Server (NTRS)

Rhatigan, Jennifer L.; Christiansen, Eric L.; Fleming, Michael L.

1990-01-01

A great deal of experimentation and analysis was performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration was found to depend upon mission specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. An approach is described which was developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented. Plans for further analyses and testing are discussed. These efforts are expected to lead to a radiator design which will perform to requirements over the expected lifetime.

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician moves a switch. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

NASA Image and Video Library

2003-08-27

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician moves a switch. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician turns on a switch. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

NASA Image and Video Library

2003-08-27

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician turns on a switch. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

Space shuttle phase B wind tunnel model and test information. Volume 3: Launch configuration

NASA Technical Reports Server (NTRS)

Glynn, J. L.; Poucher, D. E.

1988-01-01

Archived wind tunnel data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel data acquired in the Phase B development have been compiled into a data base and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include booster, orbiter and launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbital configuration types include straight and delta wings, lifting body, drop tanks and double delta wings. This is Volume 3 (Part 2) of the report -- Launch Configuration -- which includes booster and orbiter components in various stacked and tandem combinations.

Compositional variation in the Hadley Apennine region

NASA Technical Reports Server (NTRS)

Clark, P. E.; Hawke, B. R.

1982-01-01

Orbital geochemical data in the Hadley Apennine region are related to typical rock compositions and used in determining the distribution of soils derived from the rock types found in this region. Orbital XRF Mg/Si and Al/Si intensities are the orbital data that are used primarily. These data are corrected for spurious interorbit variation using a modification of a previously developed method. The corrected values are than converted to % MgO and % Al2O3, respectively, from theoretical considerations, and as such are compared with similar concentrations for typical lunar rocks and soils of the Apollo 15 landing site. The relationship of the XRF values to Fe, Ti, and Th concentrations, derived from gamma-ray observations, is also considered. It is established that the orbital geochemistry data for this region are consistent with the presence of a mixture of ANT suite and Fra Mauro basalt components frequently dominated by a KREEP basalt component toward the west and by a mafic pyroclastic component toward the east.

A Weak Bar Potential and Massive Core in the Seyfert 2 Galaxy NGC 3079: CO(1--0) observations using the Nobeyama Millimeter Array

NASA Astrophysics Data System (ADS)

Koda, J.; Sofue, Y.; Kohno, K.; Okumura, S. K.; Irwin, Judith A.

We present our recent 12CO (1-0) observations in the central molecular disk of the Hα/radio lobe galaxy NGC 3079 with the Nobeyama Millimeter Array. We show four kinematically distinct components in the observed molecular disk: a main disk, spiral arms, a nuclear disk and a nuclear core. We discuss their possible origins using a simple orbit-analysis model in a weak bar potential. We show that three of the four components are well-understood by typical gaseous orbits in a weak bar, such as gaseous x1- and x2-orbits. The main disk and spiral arms are well-understood as the gaseous x1-orbits and their associated crowding, respectively. The nuclear disk is naturally explained by the x2-orbits. However, the nuclear core, showing a high velocity of about 200kmps at a radius of about 100pc, cannot be explained by those gaseous orbits in a bar. Furthermore, no other orbits, derived by bars, cannot be responsible for the nuclear core. Thus we discuss that this component should be attributed to a central massive core with a dynamical mass of about 109Msun within the central 100pc radius. This mass is three orders of magnitude more massive than that of a central black hole in this galaxy. More detailed descriptions are presented in Koda et al. (2002).

Component-Level Electronic-Assembly Repair (CLEAR) Analysis of the Problem Reporting and Corrective Action (PRACA) Database of the International Space Station On-Orbit Electrical Systems

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.; Bradish, Martin A.; Juergens, Jeffrey R.; Lewis, Michael J.

2011-01-01

The NASA Constellation Program is investigating and developing technologies to support human exploration of the Moon and Mars. The Component-Level Electronic-Assembly Repair (CLEAR) task is part of the Supportability Project managed by the Exploration Technology Development Program. CLEAR is aimed at enabling a flight crew to diagnose and repair electronic circuits in space yet minimize logistics spares, equipment, and crew time and training. For insight into actual space repair needs, in early 2008 the project examined the operational experience of the International Space Station (ISS) program. CLEAR examined the ISS on-orbit Problem Reporting and Corrective Action database for electrical and electronic system problems. The ISS has higher than predicted reliability yet, as expected, it has persistent problems. A goal was to identify which on-orbit electrical problems could be resolved by a component-level replacement. A further goal was to identify problems that could benefit from the additional diagnostic and test capability that a component-level repair capability could provide. The study indicated that many problems stem from a small set of root causes that also represent distinct component problems. The study also determined that there are certain recurring problems where the current telemetry instrumentation and built-in tests are unable to completely resolve the problem. As a result, the root cause is listed as unknown. Overall, roughly 42 percent of on-orbit electrical problems on ISS could be addressed with a component-level repair. Furthermore, 63 percent of on-orbit electrical problems on ISS could benefit from additional external diagnostic and test capability. These results indicate that in situ component-level repair in combination with diagnostic and test capability can be expected to increase system availability and reduce logistics. The CLEAR approach can increase the flight crew s ability to act decisively to resolve problems while reducing dependency on Earth-supplied logistics for future Constellation Program missions.

Dynamical investigations of the multiple stars

NASA Astrophysics Data System (ADS)

Kiyaeva, Olga V.; Zhuchkov, Roman Ya.

2017-11-01

Two multiple stars - the quadruple star - Bootis (ADS 9173) and the triple star T Taury were investigated. The visual double star - Bootiswas studied on the basis of the Pulkovo 26-inch refractor observations 1982-2013. An invisible satellite of the component A was discovered due to long-term uniform series of observations. Its orbital period is 20 ± 2 years. The known invisible satellite of the component B with near 5 years period was confirmed due to high precision CCD observations. The astrometric orbits of the both components were calculated. The orbits of inner and outer pairs of the pre-main sequence binary T Taury were calculated on the basis of high precision observations by the VLT and on the Keck II Telescope. This weakly hierarchical triple system is stable with probability more than 70%.

Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs

NASA Astrophysics Data System (ADS)

Mason, Brian D.; Hartkopf, William I.; Tokovinin, Andrei

2010-09-01

First orbits are presented for 3 interferometric pairs and revised solutions for 15 others, based in part on first results from a recently initiated program of speckle interferometric observations of neglected southern binaries. Eight of these systems contain additional components, with multiplicity ranging up to 6.

Solaris: Orbital station: Automatic laboratory for outer space rendezvous and operations

NASA Technical Reports Server (NTRS)

Runavot, J. J.

1981-01-01

The preliminary design for a modular orbital space station (unmanned) is outlined. The three main components are a support module, an experiment module, and an orbital transport vehicle. The major types of missions (assembly, materials processing, and Earth observation) that could be performed are discussed.

Iron monocyanide (FeCN): Spin-orbit and vibronic interactions in low-lying electronic states

NASA Astrophysics Data System (ADS)

Jerosimić, Stanka V.; Milovanović, Milan Z.

2018-04-01

The spin-orbit eigenvalues of low-energy quartet and sextet spatially degenerate electronic states of FeCN are reported, together with the combined effect of vibronic and spin-orbit interaction in the lowest-lying 14Δ and 16Δ states of FeCN, by using perturbational and variational method. Spin-orbit constants (ASO) have been calculated in the basis of: (a) two components of each degenerate state, (b) four components of 14Δ and 14Π (16Δ and 16Π) states, and (c) ten components of 16Δ, 16Π, 16Σ+, 14Δ, 14Π, and 14Σ+ states. The present calculations predict the values of ASO= -77 cm-1 for 16Δ and ASO= -108 cm-1 for 14Δ state in the lowest-energy spin-orbit manifolds of each state. The major perturbing state for the 14Δ state is the 14Π state (16Π for the sextet 16Δ). As expected, based on extremely small splitting and shallowness of the bending potential energy curves for the lowest-lying 4,6Δ states, the present study indicate that the vibronic coupling does not create significant splitting of the bending levels, but the influence of anharmonicity in the bending mode is more pronounced. However, the spin-orbit fine structure dominantly influences the spectra of this species.

A complete solution for GP-B's gyroscopic precession by retarded gravitational theory

NASA Astrophysics Data System (ADS)

Tang, Keyun

Mainstream physicists generally believe that Mercury’s Perihelion precession and GP-B’ gyroscopic precession are two of the strongest evidences supporting Einstein’ curved spacetime and general relativity. However, most classical literatures and textbooks (e.g. Ohanain: Gravitation and Spacetime) paint an incorrect picture of Mercury’s orbit anomaly, namely Mercury’s perihelion precessed 43 arc-seconds per century; a correct picture should be that Mercury rotated 43 arc-seconds per century more than along Newtonian theoretical orbit. The essence of Le Verrier’s and Newcomb’s observation and analysis is that the angular speed of Mercury is slightly faster than the Newtonian theoretical value. The complete explanation to Mercury’s orbit anomaly should include two factors, perihelion precession is one of two factors, in addition, the change of orbital radius will also cause a change of angular speed, which is another component of Mercury's orbital anomaly. If Schwarzschild metric is correct, then the solution of the Schwarzschild orbit equation must contain three non-ignorable items. The first corresponds to Newtonian ellipse; the second is a nonlinear perturbation with increasing amplitude, which causes the precession of orbit perihelion; this is just one part of the angular speed anomaly of Mercury; the third part is a linear perturbation, corresponding to a similar figure of the Newton's ellipse, but with a minimal radius; this makes no contribution to the perihelion precession of the Schwarzschild orbit, but makes the Schwarzschild orbital radius slightly smaller, leading to a slight increase in Mercury’s angular speed. All classical literatures of general relativity ignored this last factor, which is a gross oversight. If you correctly take all three factors into consideration, the final result is that the difference between the angles rotated along Schwarzschild’s orbit and the angle rotated along Newton’s orbit for one hundred years should be more than 130.5 arc-seconds; this means that Le Verrier’s observation on Mercury’s orbital anomaly can not be explained correctly by the Schwarzschild metric. In contrast, Mercury’s angular speed anomaly can be explained satisfactorily by the radial induction component and angular component of retarded gravitation. From the perspective of energy, the additional radial component of retarded gravitation makes the radius of Mercury’s orbit slightly smaller, i.e. some potential energy is lost. And the angular component of retarded gravitation changes the Mercury's angular momentum; this proves that the changes of Mercury’s orbit and angular speed are the results of gravitational radiation. I have found that there are similar errors in the explanation on the gyroscopic precession of GP-B, i.e. physicists only consider the contribution of the nonlinear perturbation terms and never consider the contribution of linear perturbation terms. For the precession of GP-B, the complete Schwarzschild’s solution should be about 19.8 arc-seconds per year; it is far more than the experimental results of 6.602 arc-seconds per year. I have calculated the gyroscopic precession of GP-B due to retarded gravitation, the result is 6.607 arc-seconds per year; this matches well with the experimental results. These successful explanations for both anomalies of Mercury’s orbit and the gyroscopic precession of GP -B shows that Retarded Gravitation is indeed a sound gravitational theory, and that spacetime is in fact flat, and gravity travels at the speed of light. Both Mercury’s angular speed anomaly and GP - B gyro precession were the result of the gravitational radiation!

The Gemini NICI Planet-finding Campaign: Discovery of a Substellar L Dwarf Companion to the Nearby Young M Dwarf CD-35 2722

NASA Astrophysics Data System (ADS)

Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Clarke, Fraser; Nielsen, Eric L.; Close, Laird M.; Hayward, Thomas L.; Mamajek, Eric E.; Cushing, Michael; Dupuy, Trent; Tecza, Matthias; Thatte, Niranjan; Chun, Mark; Ftaclas, Christ; Hartung, Markus; Reid, I. Neill; Shkolnik, Evgenya L.; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; de Gouveia Dal Pino, Elisabethe; Gregorio-Hetem, Jane; Ida, Shigeru; Kuchner, Marc; Lin, Douglas N. C.; Toomey, Douglas W.

2011-03-01

We present the discovery of a wide (67 AU) substellar companion to the nearby (21 pc) young solar-metallicity M1 dwarf CD-35 2722, a member of the ≈100 Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD-35 2722 B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4±1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD-35 2722 B agree especially well the dusty field L4.5 dwarf 2MASS J22244381-0158521, while the near-IR colors and absolute magnitudes match those of the 5 Myr old L4 planetary-mass companion, 1RXS J160929.1-210524 b. Overall, CD-35 2722 B appears to be an intermediate-age benchmark for L dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T eff= 1700-1900 K and log(g)= 4.5 ± 0.5. The spectra also show that the radial velocities of components A and B agree to within ±10 km s-1, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722 B, we derive a mass of 31 ± 8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared with field objects, in contrast to the underluminosity of young late-L and early-T dwarfs. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Tidal evolution of close binary asteroid systems

NASA Astrophysics Data System (ADS)

Taylor, Patrick A.; Margot, Jean-Luc

2010-12-01

We provide a generalized discussion of tidal evolution to arbitrary order in the expansion of the gravitational potential between two spherical bodies of any mass ratio. To accurately reproduce the tidal evolution of a system at separations less than 5 times the radius of the larger primary component, the tidal potential due to the presence of a smaller secondary component is expanded in terms of Legendre polynomials to arbitrary order rather than truncated at leading order as is typically done in studies of well-separated system like the Earth and Moon. The equations of tidal evolution including tidal torques, the changes in spin rates of the components, and the change in semimajor axis (orbital separation) are then derived for binary asteroid systems with circular and equatorial mutual orbits. Accounting for higher-order terms in the tidal potential serves to speed up the tidal evolution of the system leading to underestimates in the time rates of change of the spin rates, semimajor axis, and mean motion in the mutual orbit if such corrections are ignored. Special attention is given to the effect of close orbits on the calculation of material properties of the components, in terms of the rigidity and tidal dissipation function, based on the tidal evolution of the system. It is found that accurate determinations of the physical parameters of the system, e.g., densities, sizes, and current separation, are typically more important than accounting for higher-order terms in the potential when calculating material properties. In the scope of the long-term tidal evolution of the semimajor axis and the component spin rates, correcting for close orbits is a small effect, but for an instantaneous rate of change in spin rate, semimajor axis, or mean motion, the close-orbit correction can be on the order of tens of percent. This work has possible implications for the determination of the Roche limit and for spin-state alteration during close flybys.

The early-type multiple system QZ Carinae

NASA Astrophysics Data System (ADS)

Mayer, P.; Lorenz, R.; Drechsel, H.; Abseim, A.

2001-02-01

We present an analysis of the early-type quadruple system QZ Car, consisting of an eclipsing and a non-eclipsing binary. The spectroscopic investigation is based on new high dispersion echelle and CAT/CES spectra of H and He lines. The elements for the orbit of the non-eclipsing pair could be refined. Lines of the brighter component of the eclipsing binary were detected in near-quadrature spectra, while signatures of the fainter component could be identified in only few spectra. Lines of the primary component of the non-eclipsing pair and of both components of the eclipsing pair were found to be variable in position and strength; in particular, the He ii 4686 emission line of the brighter eclipsing component is strongly variable. An ephemeris for the eclipsing binary QZ Car valid at present was derived Prim. Min. = hel. JD 2448687.16 + 5fd9991 * E. The relative orbit of the two binary constituents of the multiple system is discussed. In contrast to earlier investigations we found radial velocity changes of the systemic velocities of both binaries, which were used - together with an O-C analysis of the expected light-time effect - to derive approximate parameters of the mutual orbit of the two pairs. It is shown that this orbit and the distance to QZ Car can be further refined by minima timing and interferometry. Based on observations collected at the European Southern Observatory, La Silla, Chile.

MSFC Skylab Orbital Workshop, volume 3. [design and development of waste disposal system

NASA Technical Reports Server (NTRS)

1974-01-01

The waste management system for the Skylab Orbital Workshop is discussed. The general requirements of the system are presented. Illustrations of the components of the system are provided. Data concerning maximum expected performance capabilities are developed. The results of performance tests on the system components are reported. Emphasis is placed on the human factors engineering aspects of the system.

Libration of arguments of circumbinary-planet orbits at resonance

NASA Astrophysics Data System (ADS)

Schubart, Joachim

2017-06-01

The paper refers to fictitious resonant orbits of planet type that surround both components of a binary system. In case of 16 studied examples a suitable choice of the starting values leads to a process of libration of special angular arguments and to an evolution with an at least temporary stay of the planet in the resonant orbit. The ratio of the periods of revolution of the binary and a planet is equal to 1:5. Eight orbits depend on the ratio 1:5 of the masses of the binary components, but two other ratios appear as well. The basis of this study is the planar, elliptic or circular restricted problem of three bodies, but remarks at the end of the text refer to a four-body problem.

Two white dwarfs in ultrashort binaries with detached, eclipsing, likely sub-stellar companions detected by K2

NASA Astrophysics Data System (ADS)

Parsons, S. G.; Hermes, J. J.; Marsh, T. R.; Gänsicke, B. T.; Tremblay, P.-E.; Littlefair, S. P.; Sahman, D. I.; Ashley, R. P.; Green, M.; Rattanasoon, S.; Dhillon, V. S.; Burleigh, M. R.; Casewell, S. L.; Buckley, D. A. H.; Braker, I. P.; Irawati, P.; Dennihy, E.; Rodríguez-Gil, P.; Winget, D. E.; Winget, K. I.; Bell, Keaton J.; Kilic, Mukremin

2017-10-01

Using data from the extended Kepler mission in K2 Campaign 10, we identify two eclipsing binaries containing white dwarfs with cool companions that have extremely short orbital periods of only 71.2 min (SDSS J1205-0242, a.k.a. EPIC 201283111) and 72.5 min (SDSS J1231+0041, a.k.a. EPIC 248368963). Despite their short periods, both systems are detached with small, low-mass companions, in one case a brown dwarf and in the other case either a brown dwarf or a low-mass star. We present follow-up photometry and spectroscopy of both binaries, as well as phase-resolved spectroscopy of the brighter system, and use these data to place preliminary estimates on the physical and binary parameters. SDSS J1205-0242 is composed of a 0.39 ± 0.02 M⊙ helium-core white dwarf that is totally eclipsed by a 0.049 ± 0.006 M⊙ (51 ± 6MJ) brown-dwarf companion, while SDSS J1231+0041 is composed of a 0.56 ± 0.07 M⊙ white dwarf that is partially eclipsed by a companion of mass ≲0.095 M⊙. In the case of SDSS J1205-0242, we look at the combined constraints from common-envelope evolution and brown-dwarf models; the system is compatible with similar constraints from other post-common-envelope binaries, given the current parameter uncertainties, but has potential for future refinement.

Parametric Mass Reliability Study

NASA Technical Reports Server (NTRS)

Holt, James P.

2014-01-01

The International Space Station (ISS) systems are designed based upon having redundant systems with replaceable orbital replacement units (ORUs). These ORUs are designed to be swapped out fairly quickly, but some are very large, and some are made up of many components. When an ORU fails, it is replaced on orbit with a spare; the failed unit is sometimes returned to Earth to be serviced and re-launched. Such a system is not feasible for a 500+ day long-duration mission beyond low Earth orbit. The components that make up these ORUs have mixed reliabilities. Components that make up the most mass-such as computer housings, pump casings, and the silicon board of PCBs-typically are the most reliable. Meanwhile components that tend to fail the earliest-such as seals or gaskets-typically have a small mass. To better understand the problem, my project is to create a parametric model that relates both the mass of ORUs to reliability, as well as the mass of ORU subcomponents to reliability.

Analysis of dewar and transfer line cooldown in Superfluid Helium On-Orbit Transfer Flight Experiment (SHOOT)

NASA Technical Reports Server (NTRS)

Ng, Y. S.; Lee, J. H.

1989-01-01

The Superfluid Helium On-Orbit Transfer Flight Experiment (SHOOT) is designed to demonstrate the techniques and components required for orbital superfluid (He II) replenishment of observatories and satellites. One of the tasks planned in the experiment is to cool a warm cryogen tank and a warm transfer line to liquid helium temperature. A math model, based on single-phase vapor flow heat transfer, has been developed to predict the cooldown time, component temperature histories, and helium consumption rate, for various initial conditions of the components and for the thermomechanical pump heater powers of 2 W and 0.5 W. This paper discusses the model and the analytical results, which can be used for planning the experiment operations and determining the pump heater power required for the cooldown operation.

Electron correlation by polarization of interacting densities

NASA Astrophysics Data System (ADS)

Whitten, Jerry L.

2017-02-01

Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize dynamically, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus r12-1. A method of avoiding redundancy is described. Applications to atoms, negative ions, and molecules representing different types of bonding and spin states are discussed.

SD-4060OCPLT4 program, user's guide

NASA Technical Reports Server (NTRS)

Glazer, J.

1973-01-01

A brief description of the Orbit Comparison Plot (OCPLT4) program is presented, along with user information and a source program listing. In addition to correcting several errors that existed in the original program, this program incorporates the following new features: (1) For any satellite whose observations are processed by the Definitive Orbit Determination System (DODS), the orbital uncertainty estimates (OUE) can be obtained via appropriate card input with no major modification to the program. (2) All satellite-related information (e.g., plotter scales, cutoff limits, plotting frequencies) is user controlled via card input. (3) Not all components of OUE must be obtained. The user has the option of obtaining only the radial component if there is no need for the other two components. (4) The altitude and time graph formats are controlled by the user and are not stored for specific satellites.

Early phases in the stellar and substellar formation and evolution. Infrared and submillimeter data in the Barnard 30 dark cloud

NASA Astrophysics Data System (ADS)

Barrado, D.; de Gregorio Monsalvo, I.; Huélamo, N.; Morales-Calderón, M.; Bayo, A.; Palau, A.; Ruiz, M. T.; Rivière-Marichalar, P.; Bouy, H.; Morata, Ó.; Stauffer, J. R.; Eiroa, C.; Noriega-Crespo, A.

2018-04-01

Aims: The early evolutionary stage of brown dwarfs (BDs) is not very well characterized, especially during the embedded phase. Our goal is to gain insight into the dominant formation mechanism of very low-mass objects and BDs. Methods: We have conducted deep observations at 870 μm obtained with the LABOCA bolometer at the APEX telescope in order to identify young submillimeter (submm) sources in the Barnard 30 dark cloud. We have complemented these data with multi-wavelength observations from the optical to the far-IR and compiled complete spectral energy distributions in order to identify the counterparts, characterize the sources and to assess their membership to the association and stellar or substellar status based on the available photometric information. Results: We have identified 34 submm sources and a substantial number of possible and probable Barnard 30 members within each individual APEX/LABOCA beam. They can be classified into three distinct groups. First, 15 of these 34 have a clear optical or IR counterpart to the submm peak and nine of them are potential proto-BD candidates. Moreover, a substantial number of them could be multiple systems. A second group of 13 sources comprises candidate members with significant infrared excesses located away from the central submm emission. All of them include BD candidates, some displaying IR excess, but their association with submm emission is unclear. In addition, we have found six starless cores and, based on the total dust mass estimate, three might be pre-substellar (or pre-BDs) cores. Finally, the complete characterization of our APEX/LABOCA sources, focusing on those detected at 24 and/or 70 μm, indicates that in our sample of 34 submm sources there are, at least: two WTTs, four CTTs, five young stellar objects, eight proto-BD candidates (with another three dubious cases), and one very low luminosity objects. Conclusions: Our findings provide additional evidence concerning the BD formation mechanism, which seems to be a downsized version of the stellar formation. Tables 3-7 and reduced images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/vol/page

ARTIST CONCEPT - CUTAWAY VIEW SKYLAB 1 ORBITAL WORKSHOP (OWS)

NASA Image and Video Library

1973-05-23

S73-23919 (May 1973) --- An artist's concept illustrating a cutaway view of the Skylab 1 Orbital Workshop (OWS). The OWS is one of the five major components of the Skylab 1 space station cluster which was launched by a Saturn V on May 14, 1973 into Earth orbit. Photo credit: NASA

Artist Concept - Illustration Cutaway View - Skylab (SL)-1 Orbital Workshop (OWS)

NASA Image and Video Library

1973-05-23

S73-23918 (May 1973) --- An artist's concept illustrating a cutaway view of the Skylab 1 Orbital Workshop (OWS). The OWS is one of the five major components of the Skylab 1 space station cluster which was launched by a Saturn V on May 14, 1973 into Earth orbit. Photo credit: NASA

International Space Station: Meteoroid/Orbital Debris Survivability and Vulnerability

NASA Technical Reports Server (NTRS)

Graves, Russell

2000-01-01

This slide presentation reviews the surviability and vulnerability of the International Space Station (ISS) from the threat posed by meteoroid and orbital debris. The topics include: (1) Space station natural and induced environments (2) Meteoroid and orbital debris threat definition (3) Requirement definition (4) Assessment methods (5) Shield development and (6) Component vulnerability

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician (left) looks at the circuit breaker lights in the cabin. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

NASA Image and Video Library

2003-08-27

KENNEDY SPACE CENTER, FLA. - During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician (left) looks at the circuit breaker lights in the cabin. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

Improved definition of crustal magnetic anomalies for MAGSAT data

NASA Technical Reports Server (NTRS)

Brown, R. D.; Frawley, J. F.; Davis, W. M.; Ray, R. D.; Didwall, E.; Regan, R. D. (Principal Investigator)

1982-01-01

The routine correction of MAGSAT vector magnetometer data for external field effects such as the ring current and the daily variation by filtering long wavelength harmonics from the data is described. Separation of fields due to low altitude sources from those caused by high altitude sources is affected by means of dual harmonic expansions in the solution of Dirichlet's problem. This regression/harmonic filter procedure is applied on an orbit by orbit basis, and initial tests on MAGSAT data from orbit 1176 show reduction in external field residuals by 24.33 nT RMS in the horizontal component, and 10.95 nT RMS in the radial component.

Space shuttle phase B wind tunnel model and test information. Volume 1: Booster configuration

NASA Technical Reports Server (NTRS)

Glynn, J. L.; Poucher, D. E.

1988-01-01

Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. This is Volume 1 (Part 2) of the report -- Booster Configuration.

Space shuttle phase B wind tunnel model and test information. Volume 1: Booster configuration

NASA Technical Reports Server (NTRS)

Glynn, J. L.; Poucher, D. E.

1988-01-01

Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. This is Volume 1 (Part 1) of the report -- Booster Configuration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei, E-mail: atokovinin@ctio.noao.edu

Seven spectroscopic orbits in nearby solar-type multiple stars are presented. The primary of the chromospherically active star HIP 9642 is a 4.8 day double-lined pair; the outer 420 year visual orbit is updated, but remains poorly constrained. HIP 12780 is a quadruple system consisting of the resolved 6.7 year pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days. HIP 28790 is a young quintuple system composed of two close binaries, Aa,Ab and Ba,Bb, with periods of 221 and 13 days, respectively, and a singlemore » distant component C. Its subsystem Ba,Bb is peculiar, having a spectroscopic mass ratio of 0.89 but a magnitude difference of ∼2.2 mag. HIP 64478 also contains five stars: the A-component is a 29 year visual pair with a previously known 4 day twin subsystem, while the B-component is a contact binary with a period of 5.8 hr, seen nearly pole-on.« less

Space shuttle phase B wind tunnel model and test information. Volume 3: Launch configuration

NASA Technical Reports Server (NTRS)

Glynn, J. L.; Poucher, D. E.

1988-01-01

Archived wind tunnel test data are available for flyback booster or other alternate recoverable configuration as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle, including contractor data for an extensive variety of configurations with an array of wing and body planforms. The test data have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration. Basic components include booster, orbiter, and launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configurations include straight and delta wings, lifting body, drop tanks and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. The digital database consists of 220 files containing basic tunnel data. Database structure is documented in a series of reports which include configuration sketches for the various planforms tested. This is Volume 3 -- launch configurations.

Application of Eddy Current Techniques for Orbiter Reinforced Carbon-Carbon Structural Health Monitoring

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Simpson, John

2005-01-01

The development and application of advanced nondestructive evaluation techniques for the Reinforced Carbon-Carbon (RCC) components of the Space Shuttle Orbiter Leading Edge Structural Subsystem (LESS) was identified as a crucial step toward returning the shuttle fleet to service. In order to help meet this requirement, eddy current techniques have been developed for application to RCC components. Eddy current technology has been found to be particularly useful for measuring the protective coating thickness over the reinforced carbon-carbon and for the identification of near surface cracking and voids in the RCC matrix. Testing has been performed on as manufactured and flown RCC components with both actual and fabricated defects representing impact and oxidation damage. Encouraging initial results have led to the development of two separate eddy current systems for in-situ RCC inspections in the orbiter processing facility. Each of these systems has undergone blind validation testing on a full scale leading edge panel, and recently transitioned to Kennedy Space Center to be applied as a part of a comprehensive RCC inspection strategy to be performed in the orbiter processing facility after each shuttle flight.

Compact Resolved Ejecta in the Nearest Tidal Disruption Event

NASA Astrophysics Data System (ADS)

Perlman, Eric S.; Meyer, Eileen T.; Wang, Q. Daniel; Yuan, Qiang; Henriksen, Richard; Irwin, Judith; Krause, Marita; Wiegert, Theresa; Murphy, Eric J.; Heald, George; Dettmar, Ralf-Jürgen

2017-06-01

Tidal disruption events (TDEs) occur when a star or substellar object passes close enough to a galaxy’s supermassive black hole to be disrupted by tidal forces. NGC 4845 (d = 17 Mpc) was host to a TDE, IGR J12580+0134, detected in 2010 November. Its proximity offers us a unique close-up of the TDE and its aftermath. We discuss new Very Long Baseline Array (VLBA) and Karl G. Jansky Very Large Array observations, which show that the radio flux from the active nucleus created by the TDE has decayed in a manner consistent with predictions from a jet-circumnuclear medium interaction model. This model explains the source’s broadband spectral evolution, which shows a spectral peak that has moved from the submillimeter (at the end of 2010) to GHz radio frequencies (in 2011-2013) to < 1 {GHz} in 2015. The milliarcsecond-scale core is circularly polarized at 1.5 GHz but not at 5 GHz, consistent with the model. The VLBA images show a complex structure at 1.5 GHz that includes an east-west extension that is ˜40 mas (3 pc) long, as well as a resolved component that is 52 mas (4.1 pc) northwest of the flat-spectrum core, which is all that can be seen at 5 GHz. If ejected in 2010, the northwest component must have had v=0.96c over five years. However, this is unlikely, as our model suggests strong deceleration to speeds < 0.5c within months and a much smaller, sub-parsec size. In this interpretation, the northwest component could have either a non-nuclear origin or be from an earlier event.

Geographically correlated errors observed from a laser-based short-arc technique

NASA Astrophysics Data System (ADS)

Bonnefond, P.; Exertier, P.; Barlier, F.

1999-07-01

The laser-based short-arc technique has been developed in order to avoid local errors which affect the dynamical orbit computation, such as those due to mismodeling in the geopotential. It is based on a geometric method and consists in fitting short arcs (about 4000 km), issued from a global orbit, with satellite laser ranging tracking measurements from a ground station network. Ninety-two TOPEX/Poseidon (T/P) cycles of laser-based short-arc orbits have then been compared to JGM-2 and JGM-3 T/P orbits computed by the Precise Orbit Determination (POD) teams (Service d'Orbitographie Doris/Centre National d'Etudes Spatiales and Goddard Space Flight Center/NASA) over two areas: (1) the Mediterranean area and (2) a part of the Pacific (including California and Hawaii) called hereafter the U.S. area. Geographically correlated orbit errors in these areas are clearly evidenced: for example, -2.6 cm and +0.7 cm for the Mediterranean and U.S. areas, respectively, relative to JGM-3 orbits. However, geographically correlated errors (GCE) which are commonly linked to errors in the gravity model, can also be due to systematic errors in the reference frame and/or to biases in the tracking measurements. The short-arc technique being very sensitive to such error sources, our analysis however demonstrates that the induced geographical systematic effects are at the level of 1-2 cm on the radial orbit component. Results are also compared with those obtained with the GPS-based reduced dynamic technique. The time-dependent part of GCE has also been studied. Over 6 years of T/P data, coherent signals in the radial component of T/P Precise Orbit Ephemeris (POE) are clearly evidenced with a time period of about 6 months. In addition, impact of time varying-error sources coming from the reference frame and the tracking data accuracy has been analyzed, showing a possible linear trend of about 0.5-1 mm/yr in the radial component of T/P POE.

New White Dwarf-Brown Dwarf Binaries

NASA Astrophysics Data System (ADS)

Casewell, S. L.; Geier, S.; Lodieu, N.

2017-03-01

We present follow-up spectroscopy to 12 candidate white dwarf-brown dwarf binaries. We have confirmed that 8 objects do indeed have a white dwarf primary (7 DA, 1 DB) and two are hot subdwarfs. We have determined the Teff and log g for the white dwarfs and subdwarfs, and when combining these values with a model spectrum and the photometry, we have 3 probable white dwarf-substellar binaries with spectral types between M6 and L6.

From Stars to Super-Planets: The Low-Mass IMF in the Young Cluster IC348

NASA Technical Reports Server (NTRS)

Najita, Joan R.; Tiede, Glenn P.; Carr, John S.

2000-01-01

We investigate the low-mass population of the young cluster IC348 down to the deuterium-burning limit, a fiducial boundary between brown dwarf and planetary mass objects, using a new and innovative method for the spectral classification of late-type objects. Using photometric indices, constructed from HST/NICMOS narrow-band imaging, that measure the strength of the 1.9 micron water band, we determine the spectral type and reddening for every M-type star in the field, thereby separating cluster members from the interloper population. Due to the efficiency of our spectral classification technique, our study is complete from approximately 0.7 solar mass to 0.015 solar mass. The mass function derived for the cluster in this interval, dN/d log M alpha M(sup 0.5), is similar to that obtained for the Pleiades, but appears significantly more abundant in brown dwarfs than the mass function for companions to nearby sun-like stars. This provides compelling observational evidence for different formation and evolutionary histories for substellar objects formed in isolation vs. as companions. Because our determination of the IMF is complete to very low masses, we can place interesting constraints on the role of physical processes such as fragmentation in the star and planet formation process and the fraction of dark matter in the Galactic halo that resides in substellar objects.

The VAST Survey - IV. A wide brown dwarf companion to the A3V star ζ Delphini

NASA Astrophysics Data System (ADS)

De Rosa, R. J.; Patience, J.; Ward-Duong, K.; Vigan, A.; Marois, C.; Song, I.; Macintosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Lai, O.; McCarthy, D. W.; Kulesa, C.

2014-12-01

We report the discovery of a wide comoving substellar companion to the nearby (D = 67.5 ± 1.1 pc) A3V star ζ Delphini based on imaging and follow-up spectroscopic observations obtained during the course of our Volume-limited A-Star (VAST) multiplicity survey. ζ Del was observed over a five-year baseline with adaptive optics, revealing the presence of a previously unresolved companion with a proper motion consistent with that of the A-type primary. The age of the ζ Del system was estimated as 525 ± 125 Myr based on the position of the primary on the colour-magnitude and temperature-luminosity diagrams. Using intermediate-resolution near-infrared spectroscopy, the spectrum of ζ Del B is shown to be consistent with a mid-L dwarf (L5 ± 2), at a temperature of 1650 ± 200 K. Combining the measured near-infrared magnitude of ζ Del B with the estimated temperature leads to a model-dependent mass estimate of 50 ± 15 MJup, corresponding to a mass ratio of q = 0.019 ± 0.006. At a projected separation of 910 ± 14 au, ζ Del B is among the most widely separated and extreme-mass ratio substellar companions to a main-sequence star resolved to date, providing a rare empirical constraint of the formation of low-mass ratio companions at extremely wide separations.

The sub-stellar birth rate from UKIDSS

NASA Astrophysics Data System (ADS)

Day-Jones, A. C.; Marocco, F.; Pinfield, D. J.; Zhang, Z. H.; Burningham, B.; Deacon, N.; Ruiz, M. T.; Gallardo, J.; Jones, H. R. A.; Lucas, P. W. L.; Jenkins, J. S.; Gomes, J.; Folkes, S. L.; Clarke, J. R. A.

2013-04-01

We present a new sample of mid-L to mid-T dwarfs with effective temperatures of 1100-1700 K selected from the UKIDSS Large Area Survey (LAS) and confirmed with infrared spectra from X-shooter/Very Large Telescope. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our programme, covering 495 square degrees of sky, complete to J = 18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of masses 0.10-0.03 M⊙ and ages 1-10 Gyr. We find that the more extreme birth rates (e.g. a halo type form) can likely be excluded as the true form of the birth rate. In addition, we find that although there is substantial scatter we find a preference for a mass function, with a power-law index α in the range -1 < α < 0 that is consistent (within the errors) with the studies of late T dwarfs.

Why Compositional Convection Cannot Explain Substellar Objects’ Sharp Spectral-type Transitions

NASA Astrophysics Data System (ADS)

Leconte, Jérémy

2018-02-01

As brown dwarfs and young giant planets cool down, they are known to experience various chemical transitions—for example, from {CO} rich L-dwarfs to methane rich T-dwarfs. Those chemical transitions are accompanied by spectral transitions with sharpness that cannot be explained by chemistry alone. In a series of articles, Tremblin et al. proposed that some of the yet-unexplained features associated with these transitions could be explained by a reduction of the thermal gradient near the photosphere. To explain, in turn, this more isothermal profile, they invoke the presence of an instability analogous to fingering convection—compositional convection—triggered by the change in mean molecular weight of the gas due to the chemical transitions mentioned above. In this Letter, we use existing arguments to demonstrate that any turbulent transport, if present, would in fact increase the thermal gradient. This misinterpretation comes from the fact that turbulence mixes/homogenizes entropy (potential temperature) instead of temperature. So, while increasing transport, turbulence in an initially stratified atmosphere actually carries energy downward, whether it is due to fingering or any other type of compositional convection. These processes therefore cannot explain the features observed along the aforementioned transitions by reducing the thermal gradient in the atmosphere of substellar objects. Understanding the microphysical and dynamical properties of clouds at these transitions thus probably remains our best way forward.

Protostellar Disk Instabilities and the Formation of Substellar Companions

NASA Astrophysics Data System (ADS)

Pickett, Brian K.; Durisen, Richard H.; Cassen, Patrick; Mejia, Annie C.

2000-09-01

Recent numerical simulations of self-gravitating protostellar disks have suggested that gravitational instabilities can lead to the production of substellar companions. In these simulations, the disk is typically assumed to be locally isothermal; i.e., the initial, axisymmetric temperature in the disk remains everywhere unchanged. Such an idealized condition implies extremely efficient cooling for outwardly moving parcels of gas. While we have seen disk disruption in our own locally isothermal simulations of a small, massive protostellar disk, no long-lived companions formed as a result of the instabilities. Instead, thermal and tidal effects and the complex interactions of the disk material prevented permanent condensations from forming, despite the vigorous growth of spiral instabilities. In order to compare our results more directly with those of other authors, we here present three-dimensional evolutions of an older, larger, but less massive protostellar disk. We show that potentially long-lived condensations form only for the extreme of local isothermality, and then only when severe restrictions are placed on the natural tendency of the protostellar disk to expand in response to gravitational instabilities. A more realistic adiabatic evolution leads to vertical and radial expansion of the disk but no clump formation. We conclude that isothermal disk calculations cannot demonstrate companion formation by disk fragmentation but only suggest it at best. It will be necessary in future numerical work on this problem to treat the disk thermodynamics more realistically.

The VLBI time delay function for synchronous orbits

NASA Technical Reports Server (NTRS)

Rosenbaum, B.

1972-01-01

The VLBI is a satellite tracking technique that to date was applied largely to the tracking of synchronous orbits. These orbits are favorable for VLBI in that the remote satellite range allows continuous viewing from widely separated stations. The primary observable, geometric time delay is the time difference for signal propagation between satellite and baseline terminals. Extraordinary accuracy in angular position data on the satellite can be obtained by observation from baselines of continental dimensions. In satellite tracking though the common objective is to derive orbital elements. A question arises as to how the baseline vector bears on the accuracy of determining the elements. Our approach to this question is to derive an analytic expression for the time delay function in terms of Kepler elements and station coordinates. The analysis, which is for simplicity based on elliptic motion, shows that the resolution for the inclination of the orbital plane depends on the magnitude of the baseline polar component and the resolution for in-plane elements depends on the magnitude of a projected equatorial baseline component.

Artist's drawing of internal arrangement of orbiting Apollo and Soyuz crafts

NASA Technical Reports Server (NTRS)

1974-01-01

Artist's drawing illustrating the internal arrangement of orbiting the Apollo and Soyuz spacecraft in Earth orbit in a docked configuration. The three American Apollo crewmen and the two Soviet Soyuz crewmen will transfer to each other's spacecraft during the July Apollo Soyuz Test Project (ASTP) mission. The four ASTP visible components are, left to right, the Apollo Command Module, the Docking Module, the Soyuz Orbital Module and the Soyuz Descent Vehicle.

Tracking spin-axis orbital alignment in selected binary systems: the Torun Rossiter-McLaughlin effect survey

NASA Astrophysics Data System (ADS)

Sybilski, P.; Pawłaszek, R. K.; Sybilska, A.; Konacki, M.; Hełminiak, K. G.; Kozłowski, S. K.; Ratajczak, M.

2018-07-01

We have obtained high-resolution spectra of four eclipsing binary systems (FM Leo, NN Del, V963 Cen and AI Phe) with the view to gaining an insight into the relative orientations of their stellar spin axes and orbital axes. The so-called Rossiter-McLaughlin (RM) effect, i.e. the fact that the broadening and the amount of blue or redshift in the spectra during an eclipse depends on the tilt of the spin axis of the background star, has the potential of reconciling observations and theoretical models if such a tilt is found. We analyse the RM effect by disentangling the spectra, removing the front component and measuring the remaining, distorted lines with a broadening function (BF) obtained from single-value decomposition (SVD), weighting by the intensity centre of the BF in the eclipse. All but one of our objects show no significant misalignment, suggesting that aligned systems are dominant. We provide stellar as well as orbital parameters for our systems. With five measured spin-orbit angles, we increase significantly (from 9 to 14) the number of stars for which it has been measured. The spin-orbit angle β calculated for AI Phe's secondary component shows a misalignment of 87±17°. NN Del, with a large separation of components and a long dynamical time-scale for circularization and synchronization, is an example of a close to primordial spin-orbit angle measurement.

Is This Speck of Light an Exoplanet?

NASA Astrophysics Data System (ADS)

2004-09-01

VLT Images and Spectra of Intriguing Object near Young Brown Dwarf [1] Summary Is this newly discovered feeble point of light the long-sought bona-fide image of an exoplanet? A research paper by an international team of astronomers [2] provides sound arguments in favour, but the definitive answer is now awaiting further observations. On several occasions during the past years, astronomical images revealed faint objects, seen near much brighter stars. Some of these have been thought to be those of orbiting exoplanets, but after further study, none of them could stand up to the real test. Some turned out to be faint stellar companions, others were entirely unrelated background stars. This one may well be different. In April of this year, the team of European and American astronomers detected a faint and very red point of light very near (at 0.8 arcsec angular distance) a brown-dwarf object, designated 2MASSWJ1207334-393254. Also known as "2M1207", this is a "failed star", i.e. a body too small for major nuclear fusion processes to have ignited in its interior and now producing energy by contraction. It is a member of the TW Hydrae stellar association located at a distance of about 230 light-years. The discovery was made with the adaptive-optics supported NACO facility [3] at the 8.2-m VLT Yepun telescope at the ESO Paranal Observatory (Chile). The feeble object is more than 100 times fainter than 2M1207 and its near-infrared spectrum was obtained with great efforts in June 2004 by NACO, at the technical limit of the powerful facility. This spectrum shows the signatures of water molecules and confirms that the object must be comparatively small and light. None of the available observations contradict that it may be an exoplanet in orbit around 2M1207. Taking into account the infrared colours and the spectral data, evolutionary model calculations point to a 5 jupiter-mass planet in orbit around 2M1207. Still, they do not yet allow a clear-cut decision about the real nature of this intriguing object. Thus, the astronomers refer to it as a "Giant Planet Candidate Companion (GPCC)" [4]. Observations will now be made to ascertain whether the motion in the sky of GPCC is compatible with that of a planet orbiting 2M1207. This should become evident within 1-2 years at the most. PR Photo 26a/04: NACO image of the brown dwarf object 2M1207 and GPCC PR Photo 26b/04: Near-infrared spectrum of the brown dwarf object 2M1207 and GPCC PR Photo 26c/04: Comparison between the possible 2M1207 system and the solar system Just a speck of light ESO PR Photo 26a/04 ESO PR Photo 26a/04 The Brown Dwarf Object 2M1207 and GPCC [Preview - JPEG: 400 x 471 pix - 65k] [Normal - JPEG: 800 x 942 pix - 158k] Caption: ESO PR Photo 26a/04 is a composite image of the brown dwarf object 2M1207 (centre) and the fainter object seen near it, at an angular distance of 778 milliarcsec. Designated "Giant Planet Candidate Companion" by the discoverers, it may represent the first image of an exoplanet. Further observations, in particular of its motion in the sky relative to 2M1207 are needed to ascertain its true nature. The photo is based on three near-infrared exposures (in the H, K and L' wavebands) with the NACO adaptive-optics facility at the 8.2-m VLT Yepun telescope at the ESO Paranal Observatory. Since 1998, a team of European and American astronomers [2] is studying the environment of young, nearby "stellar associations", i.e., large conglomerates of mostly young stars and the dust and gas clouds from which they were recently formed. The stars in these associations are ideal targets for the direct imaging of sub-stellar companions (planets or brown dwarf objects). The leader of the team, ESO astronomer Gael Chauvin notes that "whatever their nature, sub-stellar objects are much hotter and brighter when young - tens of millions of years - and therefore can be more easily detected than older objects of similar mass". The team especially focused on the study of the TW Hydrae Association. It is located in the direction of the constellation Hydra (The Water-Snake) deep down in the southern sky, at a distance of about 230 light-years. For this, they used the NACO facility [3] at the 8.2-m VLT Yepun telescope, one of the four giant telescopes at the ESO Paranal Observatory in northern Chile. The instrument's adaptive optics (AO) overcome the distortion induced by atmospheric turbulence, producing extremely sharp near-infrared images. The infrared wavefront sensor was an essential component of the AO system for the success of these observations. This unique instrument senses the deformation of the near-infrared image, i.e. in a wavelength region where objects like 2M1207 (see below) are much brighter than in the visible range. The TW Hydrae Association contains a star with an orbiting brown dwarf companion, approximately 20 times the mass of Jupiter, and four stars surrounded by dusty proto-planetary disks. Brown dwarf objects are "failed stars", i.e. bodies too small for nuclear processes to have ignited in their interior and now producing energy by contraction. They emit almost no visible light. Like the Sun and the giant planets in the solar system, they are composed mainly of hydrogen gas, perhaps with swirling cloud belts. On a series of exposures made through different optical filters, the astronomers discovered a tiny red speck of light, only 0.8 arcsec from the TW Hydrae Association brown-dwarf object 2MASSWJ1207334-393254, or just "2M1207", cf. PR Photo 26a/04. The feeble image is more than 100 times fainter than that of 2M1207. "If these images had been obtained without adaptive optics, that object would not have been seen," says Gael Chauvin. Christophe Dumas, another member of the team, is enthusiastic: "The thrill of seeing this faint source of light in real-time on the instrument display was unbelievable. Although it is surely much bigger than a terrestrial-size object, it is a strange feeling that it may indeed be the first planetary system beyond our own ever imaged." Exoplanet or Brown Dwarf? ESO PR Photo 26b/04 ESO PR Photo 26b/04 The Brown Dwarf Object 2M1207 and GPCC [Preview - JPEG: 400 x 486 pix - 102k] [Normal - JPEG: 800 x 912 pix - 234k] Caption: ESO PR Photo 26b/04 shows near-infrared H-band spectra of the brown dwarf object 2M1207 and the fainter "GPCC" object seen near it, obtained with the NACO facility at the 8.2-m VLT Yepun telescope. In the upper part, the spectrum of 2M1207 (fully drawn blue curve) is compared with that of another substellar object (T513; dashed line); in the lower, the (somewhat noisy) spectrum of GPCC (fully drawn red curve) is compared with two substellar objects of different types (2M0301 and SDSS0539). The spectrum of GPCC is clearly very similar to these, confirming the substellar nature of this body. The broad dips at the left and the right are clear signatures of water in the (atmospheres of the) objects. What is the nature of this faint object [4]? Could it be an exoplanet in orbit around that young brown dwarf object at a projected distance of about 8,250 million km (about twice the distance between the Sun and Neptune)? "If the candidate companion of 2M1207 is really a planet, this would be the first time that a gravitationally bound exoplanet has been imaged around a star or a brown dwarf" says Benjamin Zuckerman of UCLA, a member of the team and also of NASA's Astrobiology Institute. Using high-angular-resolution spectroscopy with the NACO facility, the team has confirmed the substellar status of this object - now referred to as the "Giant Planet Candidate Companion (GPCC)" - by identifying broad water-band absorptions in its atmosphere, cf. PR Photo 26b/04. The spectrum of a young and hot planet - as the GPCC may well be - will have strong similarities with an older and more massive object such as a brown dwarf. However, when it cools down after a few tens of millions of years, such an object will show the spectral signatures of a giant gaseous planet like those in our own solar system. Although the spectrum of GPCC is quite "noisy" because of its faintness, the team was able to assign to it a spectral characterization that excludes a possible contamination by extra-galactic objects or late-type cool stars with abnormal infrared excess, located beyond the brown dwarf. After a very careful study of all options, the team found that, although this is statistically very improbable, the possibility that this object could be an older and more massive, foreground or background, cool brown dwarf cannot be completely excluded. The related detailed analysis is available in the resulting research paper that has been accepted for publication in the European journal Astronomy & Astrophysics (see below). Implications The brown dwarf 2M1207 has approximately 25 times the mass of Jupiter and is thus about 42 times lighter than the Sun. As a member of the TW Hydrae Association, it is about eight million years old. Because our solar system is 4,600 million years old, there is no way to directly measure how the Earth and other planets formed during the first tens of millions of years following the formation of the Sun. But, if astronomers can study the vicinity of young stars which are now only tens of millions of years old, then by witnessing a variety of planetary systems that are now forming, they will be able to understand much more accurately our own distant origins. Anne-Marie Lagrange, a member of the team from the Grenoble Observatory (France), looks towards the future: "Our discovery represents a first step towards opening a whole new field in astrophysics: the imaging and spectroscopic study of planetary systems. Such studies will enable astronomers to characterize the physical structure and chemical composition of giant and, eventually, terrestrial-like planets." Follow-up observations ESO PR Photo 26c/04 ESO PR Photo 26c/04 Comparison between the solar and 2M1207 systems [Preview - JPEG: 400 x 190 pix - 38k] [Normal - JPEG: 800 x 397 pix - 86k] [HiRes - JPEG: 2000 x 948 pix - 326k] Caption: ESO PR Photo 26c/04 shows for illustration a comparison between the solar system and the brown dwarf object 2M1207 system with its possible planet at 55 AU distance. The sizes of the objects are drawn to the same scale, but the distances have been strongly compressed. Taking into account the infrared colours and the spectral data available for GPCC, evolutionary model calculations point to a 5 jupiter-mass planet, about 55 times more distant from 2M1207 than the Earth is from the Sun (55 AU). The surface temperature appears to be about 10 times hotter than Jupiter, about 1000 °C; this is easily explained by the amount of energy that must be liberated during the current rate of contraction of this young object (indeed, the much older giant planet Jupiter is still producing energy in its interior). The astronomers will now continue their research to confirm or deny whether they have in fact discovered an exoplanet. Over the next few years, they expect to establish beyond doubt whether the object is indeed a planet in orbit around the brown dwarf 2M1207 by watching how the two objects move through space and to learn whether or not they move together. They will also measure the brightness of the GPCC at multiple wavelengths and more spectral observations may be attempted. There is no doubt that future programmes to image exoplanets around nearby stars, either from the ground with extremely large telescopes equipped with specially designed adaptive optics, or from space with special planet-finder telescopes, will greatly profit from current technological achievements. More information The results presented in this ESO Press Release are based on a research paper ("A Giant Planet Candidate near a Young Brown Dwarf" by G. Chauvin et al.) that has been accepted for publication and will appear in the leading research journal "Astronomy and Astrophysics" on September 23, 2004 (Vol. 425, Issue 2, page L29). A preprint is available here and also as astro-ph0409323. Notes [1]: This press release is issued simultaneously by ESO and CNRS (in French). [2]: The team consists of Gael Chauvin and Christophe Dumas (ESO-Chile), Anne-Marie Lagrange and Jean-Luc Beuzit (LAOG, Grenoble, France), Benjamin Zuckerman and Inseok Song (UCLA, Los Angeles, USA), David Mouillet (LAOMP, Tarbes, France) and Patrick Lowrance (IPAC, Pasadena, USA). The American members of the team acknowledge funding in part by NASA's Astrobiology Institute. [3]: The NACO facility (from NAOS/Nasmyth Adaptive Optics System and CONICA/Near-Infrared Imager and Spectrograph) at the 8.2-m VLT Yepun telescope on Paranal offers the capability to produce diffraction-limited near-infrared images of astronomical objects. It senses the radiation in this wavelength region with the N90C10 dichroic; 90 percent of the flux is transmitted to the wavefront sensor and 10 percent to the near-infrared camera CONICA. This mode is particularly useful for sharp imaging of red and very-low-mass stellar or substellar objects. The adaptive optics corrector (NAOS) was built, under an ESO contract, by Office National d'Etudes et de Recherches Aérospatiales (ONERA), Laboratoire d'Astrophysique de Grenoble (LAOG) and the LESIA and GEPI laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. [4]: What is the difference between a small brown dwarf and an exoplanet ? The border line between the two is still being investigated but it appears that a brown dwarf object is formed in the same way as stars, i.e. by contraction in an interstellar cloud while planets are formed within stable circumstellar disks via collision/accretion of planetesimals or disk instabilities. This implies that brown dwarfs are formed faster (less than 1 million years) than planets (~10 million years). Another way of separating the two kinds of objects is by mass (as this is also done between brown dwarfs and stars): (giant) planets are lighter than about 13 jupiter-masses (the critical mass needed to ignite deuterium fusion), brown dwarfs are heavier. Unfortunately, the first definition cannot be used in practice, e.g., when detecting a faint companion as in the present case, since the observations do not provide information about the way the object was formed. On the contrary, the above mass criterion is useful in the sense that spectroscopy and astrometry of a faint object, together with the appropriate evolutionary models, may reveal the mass and hence the nature of the object.

Flipping-shuttle oscillations of bright one- and two-dimensional solitons in spin-orbit-coupled Bose-Einstein condensates with Rabi mixing

NASA Astrophysics Data System (ADS)

Sakaguchi, Hidetsugu; Malomed, Boris A.

2017-10-01

We analyze the possibility of macroscopic quantum effects in the form of coupled structural oscillations and shuttle motion of bright two-component spin-orbit-coupled striped (one-dimensional, 1D) and semivortex (two-dimensional, 2D) matter-wave solitons, under the action of linear mixing (Rabi coupling) between the components. In 1D, the intrinsic oscillations manifest themselves as flippings between spatially even and odd components of striped solitons, while in 2D the system features periodic transitions between zero-vorticity and vortical components of semivortex solitons. The consideration is performed by means of a combination of analytical and numerical methods.

New observations and new models of spin-orbit coupling in binary asteroids

NASA Astrophysics Data System (ADS)

Margot, Jean-Luc; Naidu, Shantanu

2015-08-01

The YORP-induced rotational fission hypothesis is the leading candidate for explaining the formation of binaries, triples, and pairs among small (<20 km) asteroids (e.g., Margot et al, Asteroids IV, subm., 2015). Various evolutionary paths following rotational fission have been suggested, but many important questions remain about the evolutionary mechanisms and timescales. We test hypotheses about the evolution of binary asteroids by obtaining precise descriptions of the orbits and components of binary systems with radar and by examining the system dynamics with detailed numerical simulations. Predictions for component spin states and orbital precession rates can then be compared to observables in our data sets or in other data sets to elucidate the states of various systems and their likely evolutionary paths.Accurate simulations require knowledge of the masses, shapes, and spin states of individual binary components. Because radar observations can provide exquisite data sets spanning days with spatial resolutions at the decameter level, we can invert for the component shapes and measure spin states. We can also solve for the mutual orbit by fitting the observed separations between components. In addition, the superb (10e-7--10e-8) fractional uncertainties in range allow us to measure the reflex motions directly, allowing masses of individual components to be determined.We use recently published observations of the binary 2000 DP107 (Naidu et al. AJ, subm., 2015) and that of other systems to simulate the dynamics of components in well-characterized binary systems (Naidu and Margot, AJ 149, 80, 2015). We model the coupled spin and orbital motions of two rigid, ellipsoidal bodies under the influence of their mutual gravitational potential. We use surface of section plots to map the possible spin configurations of the satellites. For asynchronous satellites, the analysis reveals large regions of phase space where the spin state of the satellite is chaotic. The presence of chaotic regions may substantially increase spin synchronization timescales, delay BYORP-type evolution, extend the lifetime of binaries, and explain the observed fraction of asynchronous binaries.

One-step methods for the prediction of orbital motion, taking its periodic components into account

NASA Astrophysics Data System (ADS)

Lavrov, K. N.

1988-03-01

The paper examines the design and analysis of the properties of implicit one-step integration methods which use the trigonometric approximation of ordinary differential equations containing periodic components. With reference to an orbital-motion prediction example, it is shown that the proposed schemes are more efficient in terms of computer memory than Everhart's (1974) approach. The results obtained make it possible to improve Everhart's method.

Observations and light curve solutions of three ultrashort-period W UMa binaries

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana P.; Michel, Raul; Popov, Velimir A.; Deras, Dan

2018-07-01

Photometric observations in V, Rc and Ic bands of the ultrashort-period W UMa binaries 1SWASP J044132.96+440613.7, 1SWASP J052926.88+461147.5 and NSVS 2175434 are presented. The results from the modeling and analysis of our observations reveal that: (i) All targets undergo total eclipses and their photometric mass ratios should be accepted with confidence; (ii) All stellar components are late-type dwarfs; (iii) The temperature difference of target components does not exceed 150 K; (iv) All targets have overcontact configurations with fill-out factor around 0.24; (v) The orbit of NSVS 2175434 is slightly eccentric which is unusual for such an ultrashort-period binary; (vi) The orbital periods of all targets were improved. Masses, radii and luminosities of the stellar components were estimated by the empirical relation "period, orbital axis" for short- and ultrashort-period binaries.

Light curve solutions of the eclipsing eccentric binaries KIC 8111622, KIC 10518735, KIC 8196180 and their out-of-eclipse variability

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana P.; Vasileva, Doroteya L.

2018-02-01

We determined the orbits and stellar parameters of three eccentric eclipsing binaries by light curve solutions of their Kepler data. KIC 8111622 and KIC 10518735 undergo total eclipses while KIC 8196180 reveals partial eclipses. The target components are G and K stars, excluding the primary of KIC 8196180 which is early F star. KIC 8196180 reveals well-visible tidally-induced feature at periastron, i.e. it is an eclipsing heartbeat star. The characteristics of the observed periastron feature (shape, width and amplitude) confirm the theoretical predictions. There are additional out-of-eclipse variations of KIC 8196180 with the orbital period which may be explained by spot activity of synchronously rotating component. Besides worse visible periastron feature KIC 811162 exhibits small-amplitude light variations whose period is around 2.3 times shorter than the orbital one. These oscillations were attributed to spot(s) on asynchronously rotating component.

A three-dimensional solution for the orbit of Capella

NASA Astrophysics Data System (ADS)

Barlow, D. J.; Fekel, F. C.; Scarfe, C. D.

1993-05-01

We have combined new radial velocities of both components of Capella, obtained at McDonald and Kitt Peak, with those recently published by Batten et al. (1991), and with interferometric observations, to derive a new 3D orbit of the Capella system. Our results agree well with those of Bagnuolo and Hartkopf (1989), and yield masses accurate to +/- 3 percent. The cooler component, which is the fainter star visually but the more luminous one bolometrically, is the more massive. The mass ratio differs from unity by more than four times its uncertainty, and this lends strong support to the hypothesis that the cool component has begun to consume its core helium. If so, it may be possible to reconcile, qualitatively at least, the orbit's circularity and the stars' rotational velocities with theories of synchronization and circularization, such as that of the Tassouls (1992).

A three-dimensional solution for the orbit of Capella

NASA Technical Reports Server (NTRS)

Barlow, D. J.; Fekel, F. C.; Scarfe, C. D.

1993-01-01

We have combined new radial velocities of both components of Capella, obtained at McDonald and Kitt Peak, with those recently published by Batten et al. (1991), and with interferometric observations, to derive a new 3D orbit of the Capella system. Our results agree well with those of Bagnuolo and Hartkopf (1989), and yield masses accurate to +/- 3 percent. The cooler component, which is the fainter star visually but the more luminous one bolometrically, is the more massive. The mass ratio differs from unity by more than four times its uncertainty, and this lends strong support to the hypothesis that the cool component has begun to consume its core helium. If so, it may be possible to reconcile, qualitatively at least, the orbit's circularity and the stars' rotational velocities with theories of synchronization and circularization, such as that of the Tassouls (1992).

The Pure Rotational Spectrum of KO

NASA Astrophysics Data System (ADS)

Burton, Mark; Russ, Benjamin; Sheridan, Phillip M.; Bucchino, Matthew; Ziurys, Lucy M.

2017-06-01

The pure rotational spectrum of potassium monoxide (KO) has been recorded using millimeter-wave direct absorption spectroscopy. KO was synthesized by the reaction of potassium vapor, produced in a Broida-type oven, with nitrous oxide. No DC discharge was necessary. Eleven rotational transitions belonging to the ^{2}Π_{3/2} spin-orbit component have been measured and have been fit successfully to a case (c) Hamiltonian. Rotational and lambda-doubling constants for this spin-orbit component have been determined. It has been suggested that the ground electronic state of KO is either ^{2}Π (as for LiO and NaO) or ^{2}Σ (as for RbO and CsO), both of which lie close in energy. Recent computational studies favor a ^{2}Σ ground state. Further measurements of the rotational transitions of the ^{2}Π_{1/2} spin-orbit component and the ^{2}Σ state are currently in progress, as well as the potassium hyperfine structure.

GOATS - Orbitology Component

NASA Technical Reports Server (NTRS)

Haber, Benjamin M.; Green, Joseph J.

2010-01-01

The GOATS Orbitology Component software was developed to specifically address the concerns presented by orbit analysis tools that are often written as stand-alone applications. These applications do not easily interface with standard JPL first-principles analysis tools, and have a steep learning curve due to their complicated nature. This toolset is written as a series of MATLAB functions, allowing seamless integration into existing JPL optical systems engineering modeling and analysis modules. The functions are completely open, and allow for advanced users to delve into and modify the underlying physics being modeled. Additionally, this software module fills an analysis gap, allowing for quick, high-level mission analysis trades without the need for detailed and complicated orbit analysis using commercial stand-alone tools. This software consists of a series of MATLAB functions to provide for geometric orbit-related analysis. This includes propagation of orbits to varying levels of generalization. In the simplest case, geosynchronous orbits can be modeled by specifying a subset of three orbit elements. The next case is a circular orbit, which can be specified by a subset of four orbit elements. The most general case is an arbitrary elliptical orbit specified by all six orbit elements. These orbits are all solved geometrically, under the basic problem of an object in circular (or elliptical) orbit around a rotating spheroid. The orbit functions output time series ground tracks, which serve as the basis for more detailed orbit analysis. This software module also includes functions to track the positions of the Sun, Moon, and arbitrary celestial bodies specified by right ascension and declination. Also included are functions to calculate line-of-sight geometries to ground-based targets, angular rotations and decompositions, and other line-of-site calculations. The toolset allows for the rapid execution of orbit trade studies at the level of detail required for the early stage of mission concept development.

A dynamical study of the multiple system 17 Cygni ABFG

NASA Astrophysics Data System (ADS)

Romanenko, L. G.

2017-03-01

Adynamical study of the relative motions of the components of the inner pairs AB (ADS 12913) and FG (ADS 12889) of the quadruple heirarchical system 17 Cygni (WDS 19464+3344) is presented, as well as analysis of themotions of the outer pair AB-FG. The study is based on CCD observations obtained on the 26-inch refractor of the Pulkovo Observatory (2003-2013), position observations from the WDS catalog, Hipparcos parallaxes, and radial velocities of the components from literature data. A family of orbits for 17 Cyg AB is obtained for the first time, and has a most probable period of 6200 yrs. The apparent motion parameters (AMP) method is used, since the entire visible arc of the orbit over 1832-2013 is only 4°. The AMP method is also used to calculate the orbit of the 17 Cyg FG pair, which has a period of 238 yrs, yielding results in good agreement with the orbits derived in other studies. The ephemerides of the obtained AMP orbits, the position data for the AF pair from the WDS catalog (11 positions during 1893-2002), and Pulkovo CCD observations for 2007-2013 are used to calculate the apparent motion parameters of AB-FG outer pair, as well as a family of close-to-parabolic orbits with periods of 3.7 million years ormore. All the orbits (for both the inner and the outer pairs) are steeply inclined to theGalactic plane. Monte Carlo simulations are used to compute the probability that the outer pair is gravitationally bound, which is 47%. The similarity of the proper motions and radial velocities of all the components provides evidence that they all belong to a single stellar stream. Data from the CNS3 catalog are used to compose a list of candidate members of this stream.

The geocentric particulate distribution: Cometary, asteroidal, or space debris?

NASA Technical Reports Server (NTRS)

Mcdonnell, J. A. M.; Ratcliff, P. R.

1992-01-01

Definition of the Low Earth Orbit (LEO) particulate environment has been refined considerably with the analysis of data from NASA's Long Duration Exposure Facility (LDEF). Measurements of the impact rates from particulates ranging from sub-micron to millimetres in dimension and, especially, information on their directionality has permitted new scrunity of the sources of the particulates. Modelling of the dynamics of both bound (Earth orbital) and unbound (hyperbolic interplanetary) particulates intercepting LDEF's faces leads to the conclusion that the source is dominantly interplanetary for particle dimensions of greater than some 5 microns diameter; however the anisotropy below this dimension demands lower velocities and is compatible with an orbital component. Characteristics of the LDEF interplanetary component are compatible with familiar meteoroid sources and deep space measurements. Understanding of the orbital component which exceeds the interplanetary flux by a factor of 4 is less clear; although the very small particulates in orbit have been associated with space debris (Lawrance and Brownlee, 1986) this data conflicts with other measurements (McDonnell, Carey and Dixon, 1984) at the same epoch. By analysis of trajectories approaching the Earth and its atmosphere, we have shown that a significant contribution could be captured by aerocapture, i.e., atmospheric drag, from either asteroidal or cometary sources; such enhancement is unlikely however to provide the temporal and spatial fluctuations observed by the LDEF Interplanetary Dust Experiment (Mullholland et al. 1992). A further new mechanism is also examined, that of aerofragmentation capture, where an atmospheric grazing trajectory, which would not normally lead to capture, leads to fragmentation by thermal or mechanical shock; the microparticulates thus created can be injected in large numbers, but only into short-lifetime orbits. The concentration in one particular orbit plane, could explain the temporal fluctuations seen on LDEF; space debris could also explain the phenomenon.

Use of Orbital Conformer to Improve Speech in Patients with Confluent Maxillectomy and Orbital Defects

PubMed Central

Colebeck, Amanda C.; Kase, Michael T.; Nichols, Cindy B.; Golden, Marjorie; Huryn, Joseph M.

2016-01-01

The basic objective in prosthetic restoration of confluent maxillary and orbital defects is to achieve a comfortable, cosmetically acceptable prosthesis that restores speech, deglutition, and mastication. It is a challenging task complicated by the size and shape of the defects. The maxillary obturator prosthesis often satisfies the objective of adequate deglutition; however, orbital defects that are not obturated in the medial septal or posterior walls allow air to escape, negatively impacting phonation. This article describes a technique to achieve favorable prosthetic rehabilitation in a patient with a maxillectomy and ipsilateral orbital exenteration. The prosthetic components include maxillary obturator, orbital conformer, and orbital prosthesis connected using rigid magnetic attachments. PMID:25953143

An Astronomical Glossary.

DTIC Science & Technology

1980-02-12

planet across the limb of the Sun at the end of a transit. Elements of an Orbit - See orbital elements . Elevation - The height of a point on the...That component of libration due to variations in the geometric position of the Earth relative to the Moon. 71 ś" Orbital Elements - The quantities which...completely describe the size, shape, and orientation of an object’s orbit as well as its location in it. The classical set consists of the semi-major

Spacecraft Pointing and Position Control,

DTIC Science & Technology

1981-11-01

GEOSTATIONARY ELEMENTS As the classical set of Keplerian elements (a,e,i,a,Q, M ) is inappropriate for geosta- tionary orbits because the angular...instead of E., the set E + AE (34) - a - -LP(t 0 is obtained. Since the orbital element vector has to be computed for each measurement time, a simple orbit ...depends on the stiffness terms effected by kinematic coupling with the orbit rate 0o and the set gain K The x-component of the disturbance torque, this

High-Temperature Rocket Engine

NASA Technical Reports Server (NTRS)

Schneider, Steven J.; Rosenberg, Sanders D.; Chazen, Melvin L.

1994-01-01

Two rocket engines that operate at temperature of 2,500 K designed to provide thrust for station-keeping adjustments of geosynchronous satellites, for raising and lowering orbits, and for changing orbital planes. Also useful as final propulsion stages of launch vehicles delivering small satellites to low orbits around Earth. With further development, engines used on planetary exploration missions for orbital maneuvers. High-temperature technology of engines adaptable to gas-turbine combustors, ramjets, scramjets, and hot components of many energy-conversion systems.

Using a Multiobjective Approach to Balance Mission and Network Goals within a Delay Tolerant Network Topology

DTIC Science & Technology

2009-03-01

incorporating autonomous actions, but none appear to incorporate a cognitive aspect used to balance multiple objectives as is the focus of this work. There...routing algorithm) and/or mission type decision (orbit path change). In this component, the pseudo- cognitive aspect is implemented within the...orbit change behavior doesn’t know which orbit to choose. This is where the cognitive aspect takes over. Since the orbit change behavior doesn’t

An update on the OpenOrbiter I Mission and its paradigm's benefits for the defense, homeland security and intelligence communities

NASA Astrophysics Data System (ADS)

Straub, Jeremy

2017-05-01

The OpenOrbiter I spacecraft is the culmination of significant work on reducing the cost levels of a CubeSat-class spacecraft. By redesigning the spacecraft from the ground up, down to the component level, to use readily available electronic and physical components, the cost of CubeSat construction has been significantly reduced. This paper provides an overview of the OpenOrbiter I mission, to date. It then focuses on the benefits that can be provided by the lower-cost, low-risk spacecraft. The paper discusses the prospective utility of this mission paradigm for the defense, homeland security and intelligence communities.

Binary Plutinos

NASA Astrophysics Data System (ADS)

Noll, Keith S.

2015-08-01

The Pluto-Charon binary was the first trans-neptunian binary to be identified in 1978. Pluto-Charon is a true binary with both components orbiting a barycenter located between them. The Pluto system is also the first, and to date only, known binary with a satellite system consisting of four small satellites in near-resonant orbits around the common center of mass. Seven other Plutinos, objects in 3:2 mean motion resonance with Neptune, have orbital companions including 2004 KB19 reported here for the first time. Compared to the Cold Classical population, the Plutinos differ in the frequency of binaries, the relative sizes of the components, and their inclination distribution. These differences point to distinct dynamical histories and binary formation processes encountered by Plutinos.

THE CANADA-FRANCE ECLIPTIC PLANE SURVEY-L3 DATA RELEASE: THE ORBITAL STRUCTURE OF THE KUIPER BELT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kavelaars, J. J.; Jones, R. L.; Murray, I.

2009-06-15

We report the orbital distribution of the trans-Neptunian comets discovered during the first discovery year of the Canada-France Ecliptic Plane Survey (CFEPS). CFEPS is a Kuiper Belt object survey based on observations acquired by the Very Wide component of the Canada-France-Hawaii Telescope Legacy Survey (LS-VW). The first year's detections consist of 73 Kuiper Belt objects, 55 of which have now been tracked for three years or more, providing precise orbits. Although this sample size is small compared to the world-wide inventory, because we have an absolutely calibrated and extremely well-characterized survey (with known pointing history) we are able to de-biasmore » our observed population and make unbiased statements about the intrinsic orbital distribution of the Kuiper Belt. By applying the (publically available) CFEPS Survey Simulator to models of the true orbital distribution and comparing the resulting simulated detections to the actual detections made by the survey, we are able to rule out several hypothesized Kuiper Belt object orbit distributions. We find that the main classical belt's so-called 'cold' component is confined in semimajor axis (a) and eccentricity (e) compared to the more extended 'hot' component; the cold component is confined to lower e and does not stretch all the way out to the 2:1 resonance but rather depletes quickly beyond a = 45 AU. For the cold main classical belt population we find a robust population estimate of N(H{sub g} < 10) = 50 {+-} 5 x 10{sup 3} and find that the hot component of the main classical belt represents {approx}60% of the total population. The inner classical belt (sunward of the 3:2 mean-motion resonance) has a population of roughly 2000 trans-Neptunian objects with absolute magnitudes H{sub g} < 10, and may not share the inclination distribution of the main classical belt. We also find that the plutino population lacks a cold low-inclination component, and so, the population is somewhat larger than recent estimates; our analysis shows a plutino population of N(H{sub g} < 10){approx} 25{sup +25} {sub -12} x 10{sup 3}compared to our estimate of the size of main classical Kuiper Belt population of N(H{sub g} < 10) {approx} (126{sup +50} {sub -46}) x 10{sup 3}.« less

The spectroscopic orbits and the geometrical configuration of the symbiotic binary AR Pavonis

NASA Astrophysics Data System (ADS)

Quiroga, C.; Mikołajewska, J.; Brandi, E.; Ferrer, O.; García, L.

2002-05-01

We analyze optical and near infrared spectra of intermediate and high resolution of the eclipsing symbiotic system AR Pavonis. We have obtained the radial velocity curves for the red and the hot component from the M-giant absorption lines and from the wings of Hα , Hβ and He II lambda 4686 emission profiles, respectively. From the orbital elements we have derived the masses, Mg=2.5 Msun and Mh=1.0 Msun, for the red giant and the hot component, respectively. We also present and discuss radial velocity patterns in the blue cF absorption spectrum as well as various emission lines. In particular, we confirm that the blue absorption lines are associated with the hot component. The radial velocity curve of the blue absorption system, however, does not track the hot companion's orbital motion in a straightforward way, and its departures from an expected circular orbit are particularly strong when the hot component is active. We suggest that the cF-type absorption system is formed in material streaming from the giant presumably in a region where the stream encounters an accretion disk or an extended envelope around the hot component. The broad emission wings originate from the inner accretion disk or the envelope around the hot star. We also suggest that the central absorption in H profiles is formed in a neutral portion of the cool giant's wind which is strongly concentrated towards the orbital plane. The nebula in AR Pav seems to be bounded by significant amount of neutral material in the orbital plane. The forbidden emission lines are probably formed in low density ionized regions extended in polar directions and/or the wind-wind interaction zone. Based on observations taken at Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación and the National Universities of La Plata, Córdoba and San Juan.

A proposed search on the solar neighborhood for substellar objects

NASA Technical Reports Server (NTRS)

Reynolds, R. T.; Walker, R. G.; Tarter, J. C.

1980-01-01

The Infrared Astronomical Satellite (IRAS) program will produce an extremely sensitive all-sky survey over the wavelength region 8 to 120 microns when the mission is flown in 1982. These data will provide a novel opportunity to detect planetary-sized objects having masses smaller than 0.08 solar masses in or near the solar system. The improved detection limit of the IRAS will greatly increase the volume of space searched for such objects, as compared with previous optical and infrared studies.

Masses of the components of SB2 binaries observed with Gaia - IV. Accurate SB2 orbits for 14 binaries and masses of three binaries*

NASA Astrophysics Data System (ADS)

Kiefer, F.; Halbwachs, J.-L.; Lebreton, Y.; Soubiran, C.; Arenou, F.; Pourbaix, D.; Famaey, B.; Guillout, P.; Ibata, R.; Mazeh, T.

2018-02-01

The orbital motion of non-contact double-lined spectroscopic binaries (SB2s), with periods of a few tens of days to several years, holds unique, accurate information on individual stellar masses, which only long-term monitoring can unlock. The combination of radial velocity measurements from high-resolution spectrographs and astrometric measurements from high-precision interferometers allows the derivation of SB2 component masses down to the percent precision. Since 2010, we have observed a large sample of SB2s with the SOPHIE spectrograph at the Observatoire de Haute-Provence, aiming at the derivation of orbital elements with sufficient accuracy to obtain masses of components with relative errors as low as 1 per cent when the astrometric measurements of the Gaia satellite are taken into account. In this paper, we present the results from 6 yr of observations of 14 SB2 systems with periods ranging from 33 to 4185 days. Using the TODMOR algorithm, we computed radial velocities from the spectra and then derived the orbital elements of these binary systems. The minimum masses of the 28 stellar components are then obtained with an average sample accuracy of 1.0 ± 0.2 per cent. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 61100, HIP 95995 and HIP 101382 with relative errors for components (A,B) of, respectively, (2.0, 1.7) per cent, (3.7, 3.7) per cent and (0.2, 0.1) per cent. Using the CESAM2K stellar evolution code, we constrained the initial He abundance, age and metallicity for HIP 61100 and HIP 95995.

KEPLER ECLIPSING BINARIES WITH STELLAR COMPANIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gies, D. R.; Matson, R. A.; Guo, Z.

2015-12-15

Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars amongmore » this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.« less

Transport and Use of a Centaur Second Stage in Space

NASA Technical Reports Server (NTRS)

Strong, James M.; Morgowicz, Bernard; Drucker, Eric; Tompkins, Paul D.; Kennedy, Brian; Barber, Robert D,; Luzod, Louie T.; Kennedy, Brian Michael; Luzod, Louie T.

2010-01-01

As nations continue to explore space, the desire to reduce costs will continue to grow. As a method of cost reduction, transporting and/or use of launch system components as integral components of missions may become more commonplace in the future. There have been numerous scenarios written for using launch vehicle components (primarily space shuttle used external tanks) as part of flight missions or future habitats. Future studies for possible uses of launch vehicle upper stages might include asteroid diverter using gravity orbital perturbation, orbiting station component, raw material at an outpost, and kinetic impactor. The LCROSS (Lunar CRater Observation and Sensing Satellite) mission was conceived as a low-cost means of determining whether water exists at the polar regions of the moon. Manifested as a secondary payload with the LRO (Lunar Reconnaissance Orbiter) spacecraft aboard an Atlas V launch vehicle, LCROSS guided its spent Centaur Earth Departure Upper Stage (EDUS) into the lunar crater Cabeu's, as a kinetic impactor. This paper describes some of the challenges that the LCROSS project encountered in planning, designing, launching with and carrying the Centaur upper stage to the moon.

X-34 Main Propulsion System-Selected Subsystem Analyses

NASA Technical Reports Server (NTRS)

Brown, T. M.; McDonald, J. P.; Knight, K. C.; Champion, R. H., Jr.

1998-01-01

The X-34 hypersonic flight vehicle is currently under development by Orbital Sciences Corporation (Orbital). The Main Propulsion System (MPS) has been designed around the liquid propellant Fastrac rocket engine currently under development at NASA Marshall Space Flight Center. This paper presents selected analyses of MPS subsystems and components. Topics include the integration of component and system level modeling of the LOX dump subsystem and a simple terminal bubble velocity analysis conducted to guide propellant feed line design.

Breit interaction contribution to parity violating potentials in chiral molecules containing light nuclei.

PubMed

Berger, Robert

2008-10-21

The importance of the Breit interaction for an accurate prediction of parity violating energy differences between enantiomers is studied within electroweak quantum chemical frameworks. Besides two-electron orbit-orbit and spin-spin coupling contributions, the Breit interaction gives rise to the spin-other-orbit coupling term of the Breit-Pauli Hamiltonian. The present numerical study demonstrates that neglect of this latter term leads in hydrogen peroxide (H(2)O(2)) to relative deviations in the parity violating potential (V(pv)) by about 10%, whereas further relativistic corrections accounted for within a four-component Dirac-Hartree-Fock-Coulomb (DHFC) framework remain smaller, below 5%. Thus, the main source of discrepancy between previous one-component based (coupled perturbed) Hartree-Fock (HF) and four-component Dirac-Hartree-Fock results for parity violating potentials in H(2)O(2) is the neglect of the Breit contribution in DHFC. In heavier homologs of hydrogen peroxide the relative contribution of the spin-other-orbit coupling term to V(pv) decreases with increasing nuclear charge, whereas other relativistic effects become increasingly important. As shown for the H(2)X(2) (X = O,S,Se,Te,Po) series of molecules and for CHBrClF, to a good approximation these other relativistic influences on V(pv) can be accounted for in one-component based HF calculations with the help of relativistic enhancement factors proposed earlier in the theory of atomic parity violation.

Thermospheric mass density model error variance as a function of time scale

NASA Astrophysics Data System (ADS)

Emmert, J. T.; Sutton, E. K.

2017-12-01

In the increasingly crowded low-Earth orbit environment, accurate estimation of orbit prediction uncertainties is essential for collision avoidance. Poor characterization of such uncertainty can result in unnecessary and costly avoidance maneuvers (false positives) or disregard of a collision risk (false negatives). Atmospheric drag is a major source of orbit prediction uncertainty, and is particularly challenging to account for because it exerts a cumulative influence on orbital trajectories and is therefore not amenable to representation by a single uncertainty parameter. To address this challenge, we examine the variance of measured accelerometer-derived and orbit-derived mass densities with respect to predictions by thermospheric empirical models, using the data-minus-model variance as a proxy for model uncertainty. Our analysis focuses mainly on the power spectrum of the residuals, and we construct an empirical model of the variance as a function of time scale (from 1 hour to 10 years), altitude, and solar activity. We find that the power spectral density approximately follows a power-law process but with an enhancement near the 27-day solar rotation period. The residual variance increases monotonically with altitude between 250 and 550 km. There are two components to the variance dependence on solar activity: one component is 180 degrees out of phase (largest variance at solar minimum), and the other component lags 2 years behind solar maximum (largest variance in the descending phase of the solar cycle).

New Precision Orbits of Bright Double-Lined Spectroscopic Binaries. III. HD 82191, ω Draconis, and 108 Herculis

NASA Astrophysics Data System (ADS)

Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H.

2009-04-01

We have determined improved spectroscopic orbits for three double-lined binaries, HD 82191 (Am), ω Dra (F5 V), and 108 Her (Am), using radial velocities from the 2.1 m telescope at McDonald Observatory, the coudé feed telescope at Kitt Peak National Observatory, and 2 m telescope at Fairborn Observatory. The orbital periods range from 5.28 to 9.01 days, and all three systems have circular orbits. The new orbital dimensions (a 1 sin i and a 2 sin i) and minimum masses (m 1 sin3 i and m 2 sin3 i) have accuracies of 0.2% or better. Our improved results confirm the large minimum masses of HD 82191 and also agree with the values previously found for ω Dra. However, for the components of 108 Her our minimum masses are about 20% larger than the previous best values. We conclude that both components of HD 82191 as well as the primary of 108 Her are Am stars. However, the A9 secondary of 108 Her has normal abundances. We estimate spectral types of F4 dwarf and G0 dwarf for the components of ω Dra. The primaries of the three binaries are synchronously rotating as is the secondary of 108 Her. The secondaries of HD 82191 and ω Dra are possibly synchronously rotating.

Performance Analysis of Beidou-2/Beidou-3e Combined Solution with Emphasis on Precise Orbit Determination and Precise Point Positioning

PubMed Central

Xu, Xiaolong; Li, Min; Li, Wenwen; Liu, Jingnan

2018-01-01

In 2015, the plan for global coverage by the Chinese BeiDou Navigation Satellite System was launched. Five global BeiDou experimental satellites (BeiDou-3e) are in orbit for testing. To analyze the performances of precise orbit determination (POD) and precise point positioning (PPP) of onboard BeiDou satellites, about two months of data from 24 tracking stations were used. According to quality analysis of BeiDou-2/BeiDou-3e data, there is no satellite-induced code bias in BeiDou-3e satellites, which has been found in BeiDou-2 satellites. This phenomenon indicates that the quality issues of pseudorange data in BeiDou satellites have been solved well. POD results indicate that the BeiDou-3e orbit precision is comparable to that of BeiDou-2 satellites. The ambiguity fixed solution improved the orbit consistency of inclined geosynchronous orbit satellites in along-track and cross-track directions, but had little effect in the radial direction. Satellite laser ranging of BeiDou-3e medium Earth orbit satellites (MEOs) achieved a standard deviation of about 4 cm. Differences in clock offset series after the removal of reference clock in overlapping arcs were used to assess clock quality, and standard deviation of clock offset could reach 0.18 ns on average, which was in agreement with the orbit precision. For static PPP, when BeiDou-3e satellites were included, the positioning performance for horizontal components was improved slightly. For kinematic PPP, when global positioning satellites (GPS) were combined with BeiDou-2 and BeiDou-3e satellites, the convergence time was 13.5 min with a precision of 2–3 cm for horizontal components, and 3–4 cm for the vertical component. PMID:29304000

The effect of symmetry on the U L3 NEXAFS of octahedral coordinated uranium(vi)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagus, Paul S.; Nelin, Connie J.; Ilton, Eugene S.

2017-03-21

We describe a detailed theoretical analysis of how distortions from ideal cubic or Oh symmetry affect the shape, in particular the width, of the U L3-edge NEXAFS for U(VI) in octahedral coordination. The full-width-half-maximum (FWHM) of the L3-edge white line decreases with increasing distortion from Oh symmetry due to the mixing of symmetry broken t2g and eg components of the excited state U(6d) orbitals. The mixing is allowed because of spin-orbit splitting of the ligand field split 6d orbitals. Especially for higher distortions, it is possible to identify a mixing between one of the t2g and one of the egmore » components, allowed in the double group representation when the spin-orbit interaction is taken into account. This mixing strongly reduces the ligand field splitting, which, in turn, leads to a narrowing of the U L3 white line. However, the effect of this mixing is partially offset by an increase in the covalent anti-bonding character of the highest energy spin-orbit split eg orbital. At higher distortions, mixing overwhelms the increasing anti-bonding character of this orbital which leads to an accelerated decrease in the FWHM with increasing distortion. Additional evidence for the effect of mixing of t2g and eg components is that the FWHM of the white line narrows whether the two axial U-O bond distances shorten or lengthen. Our ab initio theory uses relativistic wavefunctions for cluster models of the structures; empirical or semi-empirical parameters were not used to adjust prediction to experiment. A major advantage is that it provides a transparent approach for determining how the character and extent of the covalent mixing of the relevant U and O orbitals affect the U L3-edge white line.« less

X-37 C-Sic CMC Control Surface Components Development [Status of the NASA/Boeing/USAF Orbital Vehicle and Related Efforts

NASA Technical Reports Server (NTRS)

Valentine, Peter G; Rivers, H. Kevin; Chen, Victor L.

2004-01-01

Carbon/Silicon-Carbide (C-Sic) ceramic matrix composite (CMC) flaperon and ruddervator control surface components are being developed for the X-37 Orbital Vehicle (OV). The results of the prior NASA LaRC led work, aimed at developing C-Sic flaperon and ruddervator components for the X-37, will be reviewed. The status of several on-going and/or planned NASA, USAF, and Boeing programs that will support the development of control surface components for the X-37 OV will also be reviewed. The overall design and development philosophy being employed to assemble a team(s) to develop both: (a) C-Sic hot structure control surface components for the X-37 OV, and (b) carbon-carbon (C-C) hot structure components (a risk-reduction backup option for the OV), will be presented.

Impact of clouds in the JWST and LUVOIR simulated transmission spectra of TRAPPIST-1 planets in the habitable zone

NASA Astrophysics Data System (ADS)

Fauchez, Thomas; Turbet, Martin; Mandell, Avi; Kopparapu, Ravi Kumar; Arney, Giada; Domagal-Goldman, Shawn

2018-06-01

M-dwarfs are the most common type of stars in our galaxy. Ultra-cool dwarfs (T < 2700 K) are a sub-stellar class of late M-dwarfs and represent nearly ~ 15% of astronomical objects in the stellar neighborhood of the Sun. Their smaller size than regular M-dwarfs allows easier detection of rocky exoplanets in close orbits, and this potential was recently realized by the discovery of the TRAPPIST-1 system. Located about 12 pc away, TRAPPIST-1 has seven known planets, and it is one of the most promising rocky-planet systems for follow-up observations due to the depths of the transit signals. Transit-timing variation (TTVs) measurements of the TRAPPIST-1 planets suggest terrestrial or volatile-rich composition. Also, it has been found that three planets (TRAPPIST-1 e, f and g) are in the Habitable Zone (HZ) where surface temperatures would allow surface water to exist. These planets will be prime targets for atmospheric characterization with JWST owing to their relative proximity to Earth and frequent planetary transits.Atmospheric properties are major components of planet habitability. However, the detectability of gaseous features on rocky planets in the HZ may be severely impacted by the presence of clouds and/or hazes in their atmosphere. We have already seen this phenomenon in the “flat” transit transmission spectra of larger exoplanets such as GJ 1214b, WASP-31b, WASP-12b and HATP-12b.In this work, we use the LMDG global climate model to simulate several possibilities of atmospheres for TRAPPIST-1 e, f and 1g: 1) Archean Earth, 2) modern Earth and 3) CO2-dominated atmospheres. We also calculate synthetic transit spectra using the GSFC Planetary Spectrum Generator (PSG), and determine the number of transits needed to observe key spectral features for both JWST and future telescopes (ARIEL, LUVOIR, HabEx). We will identify differences in the spectra of cloudy vs non-cloudy, and determine how much information on spatial variability in atmosphere characteristics can be extracted from time-resolved transit and eclipse mapping. A particular attention will be given to the impact of the atmospheric variability when adding transit spectra, and how this may affect atmospheric parameter retrievals.

HD 143 418 - An Interacting Binary with a Subsynchronously Rotating Primary

NASA Astrophysics Data System (ADS)

Mikulášek, Z.; Zverko, J.; Žižňovský, J.; Krtička, J.; Iliev, I. Kh.; Kudryavtsev, D. O.; Gráf, T.; Zejda, M.

2010-12-01

HD 143418 is a non-eclipsing double-lined close binary with orbital period Porb=2.282520 d. The photometrically and spectroscopically dominant primary component is a normal A5V star in the middle of its stay on the main sequence with extremely slow, subsynchronous rotation (Prot being about 14 days!). Its photometric monitoring since 1982 revealed orbitally modulated variations with changing form and amplitude. The advanced principal component analysis (APCA) disentangling extract-ed a steady part of light curves obviously caused by the ellipticity of the primary. Seasonal components of the light curves may be related to an expected incidence of circumstellar matter ejected from the tidally spinning up primary component. A possible scenario of the synchronisation process is also briefly discussed.

Angular momentum exchange in white dwarf binaries accreting through direct impact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sepinsky, J. F.; Kalogera, V., E-mail: jeremy.sepinsky@scranton.edu, E-mail: vicky@northwestern.edu

We examine the exchange of angular momentum between the component spins and the orbit in semi-detached double white dwarf binaries undergoing mass transfer through direct impact of the transfer stream. We approximate the stream as a series of discrete massive particles ejected in the ballistic limit at the inner Lagrangian point of the donor toward the accretor. This work improves upon similar earlier studies in a number of ways. First, we self-consistently calculate the total angular momentum of the orbit at all times. This includes changes in the orbital angular momentum during the ballistic trajectory of the ejected mass, asmore » well as changes during the ejection/accretion due to the radial component of the particle's velocity. Second, we calculate the particle's ballistic trajectory for each system, which allows us to determine the precise position and velocity of the particle upon accretion. We can then include specific information about the radius of the accretor as well as the angle of impact. Finally, we ensure that the total angular momentum is conserved, which requires the donor star spin to vary self-consistently. With these improvements, we calculate the angular momentum change of the orbit and each binary component across the entire parameter space of direct impact double white dwarf binary systems. We find a significant decrease in the amount of angular momentum removed from the orbit during mass transfer, as well as cases where this process increases the angular momentum of the orbit at the expense of the spin angular momentum of the donor. We conclude that, unlike earlier claims in the literature, mass transfer through direct impact need not destabilize the binary and that the quantity and sign of the orbital angular momentum transfer depends on the binary properties, particularly the masses of the double white dwarf binary component stars. This stabilization may significantly impact the population synthesis calculations of the expected numbers of events/systems for which double white dwarfs may be a progenitor, e.g., Type Ia supernovae, Type.Ia supernovae, and AM CVn.« less

Synchronous orbit power technology needs

NASA Technical Reports Server (NTRS)

Slifer, L. W., Jr.; Billerbeck, W. J.

1979-01-01

The needs are defined for future geosynchronous orbit spacecraft power subsystem components, including power generation, energy storage, and power processing. A review of the rapid expansion of the satellite communications field provides a basis for projection into the future. Three projected models, a mission model, an orbit transfer vehicle model, and a mass model for power subsystem components are used to define power requirements and mass limitations for future spacecraft. Based upon these three models, the power subsystems for a 10 kw, 10 year life, dedicated spacecraft and for a 20 kw, 20 year life, multi-mission platform are analyzed in further detail to establish power density requirements for the generation, storage and processing components of power subsystems as related to orbit transfer vehicle capabilities. Comparison of these requirements to state of the art design values shows that major improvements, by a factor of 2 or more, are needed to accomplish the near term missions. However, with the advent of large transfer vehicles, these requirements are significantly reduced, leaving the long lifetime requirement, associated with reliability and/or refurbishment, as the primary development need. A few technology advances, currently under development, are noted with regard to their impacts on future capability.

Analysis of the multiple system with chemically peculiar component φ Draconis

NASA Astrophysics Data System (ADS)

Liška, J.

2016-09-01

The star ϕ Dra comprises a spectroscopic binary and a third star that together form a visual triple system. It is one of the brightest chemically peculiar stars of the upper main sequence. Despite these facts, no comprehensive study of its multiplicity has been performed yet. In this work, we present a detailed analysis of the triple system based on available measurements. We use radial velocities taken from four sources in the literature in a re-analysis of the inner spectroscopic binary (Aab). An incorrect value of the orbital period of the inner system Aab about 27 d was accepted in literature more than 40 yr. A new solution of orbit with the 128-d period was determined. Relative position measurements of the outer visual binary system (AB) from Washington Double Star Catalog were compared with known orbital models. Furthermore, it was shown that astrometric motion in system AB is well described by the model of Andrade with a 308-yr orbital period. Parameters of A and B components were utilized to estimate individual brightness for all components and their masses from evolutionary tracks. Although we found several facts which support the gravitational bond between them, unbound solution cannot be fully excluded yet.

Discovery Orbiter Major Modifications

NASA Image and Video Library

2003-08-27

During power-up of the orbiter Discovery in the Orbiter Processing Facility, a technician moves a circuit reset on the cockpit console. Discovery has been undergoing Orbiter Major Modifications in the past year, ranging from wiring, control panels and black boxes to gaseous and fluid systems tubing and components. These systems were deserviced, disassembled, inspected, modified, reassembled, checked out and reserviced, as were most other systems onboard. The work includes the installation of the Multifunction Electronic Display Subsystem (MEDS) - a state-of-the-art “glass cockpit.”

Cutaway view of the Command/Service modules of Apollo 10 lunar orbit mission

NASA Image and Video Library

1969-05-19

S69-34072 (May 1969) --- Artist's drawing illustrating a cutaway view of the Command and Service Modules of the Apollo 10 lunar orbit mission. Arrows point to various components and features of the CSM.

Chromospherically Active Stars. XXV. HD 144110=EV Draconis, a Double-lined Dwarf Binary

NASA Astrophysics Data System (ADS)

Fekel, Francis C.; Henry, Gregory W.; Lewis, Ceteka

2005-08-01

New spectroscopic and photometric observations of HD 144110 have been used to obtain an improved orbital element solution and determine some basic properties of the system. This chromospherically active, double-lined spectroscopic binary has an orbital period of 1.6714012 days and a circular orbit. We classify the components as G5 V and K0 V and suggest that they are slightly metal-rich. The photometric observations indicate that the rotation of HD 144110 is synchronous with the orbital period. Despite the short orbital period, no evidence of eclipses is seen in our photometry.

Performance Characteristics For The Orbiter Camera Payload System's Large Format Camera (LFC)

NASA Astrophysics Data System (ADS)

MoIIberg, Bernard H.

1981-11-01

The Orbiter Camera Payload System, the OCPS, is an integrated photographic system which is carried into Earth orbit as a payload in the Shuttle Orbiter vehicle's cargo bay. The major component of the OCPS is a Large Format Camera (LFC) which is a precision wide-angle cartographic instrument that is capable of produc-ing high resolution stereophotography of great geometric fidelity in multiple base to height ratios. The primary design objective for the LFC was to maximize all system performance characteristics while maintaining a high level of reliability compatible with rocket launch conditions and the on-orbit environment.

The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin-Orbit Misalignment

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Kraus, Adam L.; Bryan, Marta L.; Knutson, Heather A.; Brogi, Matteo; Rizzuto, Aaron C.; Mace, Gregory N.; Vanderburg, Andrew; Liu, Michael C.; Hillenbrand, Lynne A.; Cieza, Lucas A.

2017-10-01

ROXs 12 (2MASS J16262803-2526477) is a young star hosting a directly imaged companion near the deuterium-burning limit. We present a suite of spectroscopic, imaging, and time-series observations to characterize the physical and environmental properties of this system. Moderate-resolution near-infrared spectroscopy of ROXs 12 B from Gemini-North/NIFS and Keck/OSIRIS reveals signatures of low surface gravity including weak alkali absorption lines and a triangular H-band pseudocontinuum shape. No signs of Paβ emission are evident. As a population, however, we find that about half (46% ± 14%) of young (≲15 Myr) companions with masses ≲20 M Jup possess actively accreting subdisks detected via Paβ line emission, which represents a lower limit on the prevalence of circumplanetary disks in general, as some are expected to be in a quiescent phase of accretion. The bolometric luminosity of the companion and age of the host star ({6}-2+4 Myr) imply a mass of 17.5 ± 1.5 M Jup for ROXs 12 B based on hot-start evolutionary models. We identify a wide (5100 au) tertiary companion to this system, 2MASS J16262774-2527247, that is heavily accreting and exhibits stochastic variability in its K2 light curve. By combining v sin I * measurements with rotation periods from K2, we constrain the line-of-sight inclinations of ROXs 12 A and 2MASS J16262774-2527247 and find that they are misaligned by {{60}-11+7}^\\circ . In addition, the orbital axis of ROXs 12 B is likely misaligned from the spin axis of its host star, ROXs 12 A, suggesting that ROXs 12 B formed akin to fragmenting binary stars or in an equatorial disk that was torqued by the wide stellar tertiary. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The SOPHIE search for northern extrasolar planets. X. Detection and characterization of giant planets by the dozen

NASA Astrophysics Data System (ADS)

Hébrard, G.; Arnold, L.; Forveille, T.; Correia, A. C. M.; Laskar, J.; Bonfils, X.; Boisse, I.; Díaz, R. F.; Hagelberg, J.; Sahlmann, J.; Santos, N. C.; Astudillo-Defru, N.; Borgniet, S.; Bouchy, F.; Bourrier, V.; Courcol, B.; Delfosse, X.; Deleuil, M.; Demangeon, O.; Ehrenreich, D.; Gregorio, J.; Jovanovic, N.; Labrevoir, O.; Lagrange, A.-M.; Lovis, C.; Lozi, J.; Moutou, C.; Montagnier, G.; Pepe, F.; Rey, J.; Santerne, A.; Ségransan, D.; Udry, S.; Vanhuysse, M.; Vigan, A.; Wilson, P. A.

2016-04-01

We present new radial velocity measurements of eight stars that were secured with the spectrograph SOPHIE at the 193 cm telescope of the Haute-Provence Observatory. The measurements allow detecting and characterizing new giant extrasolar planets. The host stars are dwarfs of spectral types between F5 and K0 and magnitudes of between 6.7 and 9.6; the planets have minimum masses Mp sin I of between 0.4 to 3.8 MJup and orbitalperiods of several days to several months. The data allow only single planets to be discovered around the first six stars (HD 143105, HIP 109600, HD 35759, HIP 109384, HD 220842, and HD 12484), but one of them shows the signature of an additional substellar companion in the system. The seventh star, HIP 65407, allows the discovery of two giant planets that orbit just outside the 12:5 resonance in weak mutual interaction. The last star, HD 141399, was already known to host a four-planet system; our additional data and analyses allow new constraints to be set on it. We present Keplerian orbits of all systems, together with dynamical analyses of the two multi-planet systems. HD 143105 is one of the brightest stars known to host a hot Jupiter, which could allow numerous follow-up studies to be conducted even though this is not a transiting system. The giant planets HIP 109600b, HIP 109384b, and HD 141399c are located in the habitable zone of their host star. Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (programs 07A.PNP.CONS to 15A.PNP.CONS).Full version of the SOPHIE measurements (Table 1) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A145

Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

NASA Astrophysics Data System (ADS)

Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G.

2011-04-01

Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3 d. Here we report the discovery of a low mass companion (M2 > 0.14 M⊙) orbiting the sdB star and central star of a planetary nebula EGB 5 with an orbital period of 16.5 d at a minimum separation of 23 R⊙. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB 5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes No. 167.H-0407(A) and 71.D-0383(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Some of the data used in this work were obtained at the William Herschel Telescope (WHT) operated by the Isaac Newton Group of Telescopes (ING).

Spectroscopic orbits of nearby solar-type dwarfs - II.

NASA Astrophysics Data System (ADS)

Gorynya, N. A.; Tokovinin, A.

2018-03-01

Several nearby solar-type dwarfs with variable radial velocity were monitored to find their spectroscopic orbits. First orbital elements of 15 binaries (HIP 12144, 17895, 27970, 32329, 38636, 39072, 40479, 43004, 73700, 79234, 84696, 92140, 88656, 104514, and 112222) are determined. The previously known orbits of HIP 5276, 21443, 28678, and 41214 are confirmed and updated. The orbital periods range from 2 d to 4 yr. There are eight hierarchical systems with additional distant companions among those 19 stars. The outer visual orbit of the triple system HIP 17895 is updated and the masses of all its components are estimated. We provide radial velocities of another 16 Hipparcos stars without orbital solutions, some of those with long periods or false claims of variability.

Trajectory design for Saturnian Ocean Worlds orbiters using multidimensional Poincaré maps

NASA Astrophysics Data System (ADS)

Davis, Diane Craig; Phillips, Sean M.; McCarthy, Brian P.

2018-02-01

Missions based on low-energy orbits in the vicinity of planetary moons, such as Titan or Enceladus, involve significant end-to-end trajectory design challenges due to the gravitational effects of the distant larger primary. To address these challenges, the current investigation focuses on the visualization and use of multidimensional Poincaré maps to perform preliminary design of orbits with significant out-of-plane components, including orbits that provide polar coverage. Poincaré maps facilitate the identification of families of solutions to a given orbit problem and provide the ability to easily respond to changing inputs and requirements. A visual-based design process highlights a variety of trajectory options near Saturn's ocean worlds, including both moon-centered orbits and libration point orbits.

The spectroscopic binary system Gl 375. I. Orbital parameters and chromospheric activity

NASA Astrophysics Data System (ADS)

Díaz, R. F.; González, J. F.; Cincunegui, C.; Mauas, P. J. D.

2007-11-01

Aims:We study the spectroscopic binary system Gl 375 to characterise its orbit and the spectral types and chromospheric activity levels of the components. Methods: We employed medium-resolution echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory CASLEO and photometric observations obtained from the ASAS database. Results: We have separated the composite spectra into those corresponding to both components. The separated spectra allow us to confirm that the spectral types of both components are similar (dMe3.5) and to obtain precise measurements of the orbital period (P = 1.87844 days), minimum masses (M_1 sin3 i = 0.35 {M}_⊙ and M_2 sin3 i =0.33 {M}_⊙), and other orbital parameters. The photometric observations exhibit a sinusoidal variation with the same period as the orbital period. We interpreted this as signs of active regions carried along with rotation in a tidally synchronised system, and studied the evolution of the amplitude of the modulation on longer timescales. Together with the mean magnitude, the modulation exhibits a roughly cyclic variation with a period of around 800 days. This periodicity is also found in the flux of the Ca II K lines of both components, which seem to be in phase. Conclusions: The periodic changes in the three observables are interpreted as a sign of a stellar activity cycle. Both components appear to be in phase, which implies that they are magnetically connected. The measured cycle of ≈2.2 years (≈800 days) is consistent with previous determinations of activity cycles in similar stars. The authors are visiting astronomers of the Complejo Astronómico El Leoncito, operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials.

PubMed

Chattopadhyaya, Surya; Nath, Abhijit; Das, Kalyan Kumar

2014-04-24

Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study. Copyright © 2014 Elsevier B.V. All rights reserved.

Vehicle for Space Transfer and Recovery (VSTAR), volume 1

NASA Technical Reports Server (NTRS)

1988-01-01

The Vehicle Space Transfer and Recovery (VSTAR) system is designed as a manned orbital transfer vehicle (MOTV) with the primary mission of Satellite Launch and Repair (SLR). VSTAR will provide for economic use of high altitude spaceflight for both the public and private sector. VSTAR components will be built and tested using earth based facilities. These components will then be launched using the space shuttle, into low earth orbit (LEO) where it will be constructed on a U.S. built space station. Once in LEO the vehicle components will be assembled in modules which can then be arranged in various configurations to perform the required missions.

Thermal Modeling of the Mars Reconnaissance Orbiter's Solar Panel and Instruments during Aerobraking

NASA Technical Reports Server (NTRS)

Dec, John A.; Gasbarre, Joseph F.; Amundsen, Ruth M.

2007-01-01

The Mars Reconnaissance Orbiter (MRO) launched on August 12, 2005 and started aerobraking at Mars in March 2006. During the spacecraft s design phase, thermal models of the solar panels and instruments were developed to determine which components would be the most limiting thermally during aerobraking. Having determined the most limiting components, thermal limits in terms of heat rate were established. Advanced thermal modeling techniques were developed utilizing Thermal Desktop and Patran Thermal. Heat transfer coefficients were calculated using a Direct Simulation Monte Carlo technique. Analysis established that the solar panels were the most limiting components during the aerobraking phase of the mission.

VizieR Online Data Catalog: BVIc light curves of SZ Cam (Tamajo+, 2012)

NASA Astrophysics Data System (ADS)

Tamajo, E.; Munari, U.; Siviero, A.; Tomasella, L.; Dallaporta, S.

2012-01-01

We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P=2.7-days in a long orbit (~55yrs) around a non-eclipsing SB1 pair of orbital period P=2.8-days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BV IC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a beta Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is 0.33265+/-0.00005-days and the observed total amplitude in the B band is 0.0105+/-0.0005mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution. (1 data file).

Space Radiation Effects and Reliability Consideration for the Proposed Jupiter Europa Orbiter

NASA Technical Reports Server (NTRS)

Johnston, Allan

2011-01-01

The proposed Jupiter Europa Orbiter (JEO) mission to explore the Jovian moon Europa poses a number of challenges. The spacecraft must operate for about seven years during the transit time to the vicinity of Jupiter, and then endure unusually high radiation levels during exploration and orbiting phases. The ability to withstand usually high total dose levels is critical for the mission, along with meeting the high reliability standards for flagship NASA missions. Reliability of new microelectronic components must be sufficiently understood to meet overall mission requirements.The proposed Jupiter Europa Orbiter (JEO) mission to explore the Jovian moon Europa poses a number of challenges. The spacecraft must operate for about seven years during the transit time to the vicinity of Jupiter, and then endure unusually high radiation levels during exploration and orbiting phases. The ability to withstand usually high total dose levels is critical for the mission, along with meeting the high reliability standards for flagship NASA missions. Reliability of new microelectronic components must be sufficiently understood to meet overall mission requirements.

First Visual Orbit for the Prototypical Colliding-wind Binary WR 140

NASA Astrophysics Data System (ADS)

Monnier, John D.; Zhao, M.; Pedretti, E.; Millan-Gabet, R.; Berger, J.; Schloerb, F.; Traub, W.; ten Brummelaar, T.; McAlister, H.; Ridgway, S.; Turner, N.; Sturmann, L.; Sturmann, J.; Baron, F.; Tannirkulam, A.; Kraus, S.; Williams, P.

2012-01-01

Wolf-Rayet stars represent one of the final stages of massive stellar evolution. Relatively little is known about this short-lived phase and we currently lack reliable mass, distance, and binarity determinations for a representative sample. Here we report the first visual orbit for WR 140 (=HD193793), a WC7+O5 binary system known for its periodic dust production episodes triggered by intense colliding winds near periastron passage. The IOTA and CHARA interferometers resolved the pair of stars in each year from 2003--2009, covering most of the highly-eccentric, 7.9 year orbit. Combining our results with the recent improved double-line spectroscopic orbit of Fahed et al. (2011), we can estimate the distance to WR 140 with about 2% error and estimate component masses with about 4% error. Our precision orbit yields key parameters with uncertainties about 6 times smaller than previous work and paves the way for detailed modeling of the system. Our newly measured flux ratios at the near-infrared H and Ks bands allow an SED decomposition and analysis of the component evolutionary states.

R & D GTDS SST: Code Flowcharts and Input

DTIC Science & Technology

1995-01-01

trajectory from a given set of initial conditions Typical output is in the form of a printer le of Cartesian coordinates and Keplerian orbital ... orbiting the Earth The input data specied for an EPHEM run are i Initial elements and epoch ii Orbit generator selection iii Conversion of osculating...discussed ELEMENT sets coordinate system reference central body and rst components of initial state ELEMENT sets the second

Preliminary Design, Simulation, and Test of the Electrical Power Subsystem of the TINYSCOPE Nanosatellite

DTIC Science & Technology

2009-12-01

VACUUM TEST NOTES..................................... 173 LIST OF REFERENCES ...test, and operate a low earth-orbiting (LEO) proto-flight unit using the following guiding principles: 3 • Use COTS components or slightly...orbit must be replaced on that same orbit during the satellite’s non- eclipse period. This is stated mathematically as, bd d bc cP T P T× ≤ × (1

Classifying orbits in galaxy models with a prolate or an oblate dark matter halo component

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.

2014-03-01

Aims: The distinction between regular and chaotic motion in galaxies is undoubtedly an issue of paramount importance. We explore the nature of orbits of stars moving in the meridional plane (R,z) of an axially symmetric galactic model with a disk, a spherical nucleus, and a flat biaxial dark matter halo component. In particular, we study the influence of all the involved parameters of the dynamical system by computing both the percentage of chaotic orbits and the percentages of orbits of the main regular resonant families in each case. Methods: To distinguish between ordered and chaotic motion, we use the smaller alignment index (SALI) method to extensive samples of orbits by numerically integrating the equations of motion as well as the variational equations. Moreover, a method based on the concept of spectral dynamics that utilizes the Fourier transform of the time series of each coordinate is used to identify the various families of regular orbits and also to recognize the secondary resonances that bifurcate from them. Two cases are studied for every parameter: (i) the case where the halo component is prolate and (ii) the case where an oblate dark halo is present. Results: Our numerical investigation indicates that all the dynamical quantities affect, more or less, the overall orbital structure. It was observed that the mass of the nucleus, the halo flattening parameter, the scale length of the halo, the angular momentum, and the orbital energy are the most influential quantities, while the effect of all the other parameters is much weaker. It was also found that all the parameters corresponding to the disk only have a minor influence on the nature of orbits. Furthermore, some other quantities, such as the minimum distance to the origin, the horizontal, and the vertical force, were tested as potential chaos detectors. Our analysis revealed that only general information can be obtained from these quantities. We also compared our results with early related work. Appendix A is available in electronic form at http://www.aanda.org

Towards GPS orbit accuracy of tens of centimeters

NASA Technical Reports Server (NTRS)

Lichten, Stephen M.

1990-01-01

In this paper, CASA Uno orbit results are presented utilizing data from four continents. Refinements in orbit modeling, combined with the availability of a worldwide tracking network and the dense distribution of tracking sites in North and South America, have improved orbit determination precision to about 60 cm (per component) for four of the seven GPS satellites tracked in CASA Uno. The orbit results are consistent with California baseline repeatabilities, which are at the few mm level in horizontal and length, and 1-2 cm in the vertical. Baseline comparisons with VLBI provide a measure of orbit accuracy, showing sub-cm agreement in length and 1.5 cm agreement in the horizontal.

Orbital debris issues

NASA Technical Reports Server (NTRS)

Kessler, D. J.

1985-01-01

Man-made orbital debris, identified as a potential hazard to future space activities, is grouped into size categories. At least 79 satellites have broken up in orbit to date and, in combination with exploded rocket casings and antisatellite debris, threaten 10 km/sec collisions with other orbiting platforms. Only 5 percent of the debris is connected to payloads. The total population of orbiting objects over 4 cm in diameter could number as high as 15,000, and at 1 cm in diameter could be 32,000, based on NASA and NORAD studies. NASA has initiated the 10 yr Space Debris Assessment Program to characterize the hazards of orbiting debris, the potential damage to typical spacecraft components, and to identify means of controlling the damage.

GPS-based precision orbit determination - A Topex flight experiment

NASA Technical Reports Server (NTRS)

Melbourne, William G.; Davis, Edgar S.

1988-01-01

Plans for a Topex/Poseiden flight experiment to test the accuracy of using GPS data for precision orbit determination of earth satellites are presented. It is expected that the GPS-based precision orbit determination will provide subdecimeter accuracies in the radial component of the Topex orbit when the extant gravity model is tuned for wavelengths longer than about 1000 kms. The concept, design, flight receiver, antenna system, ground processing, and data processing of GPS are examined. Also, an accurate quasi-geometric orbit determination approach called nondynamic or reduced dynamic tracking which relies on the use of the pseudorange and the carrier phase measurements to reduce orbit errors arising from mismodeled dynamics is discussed.

Ballistic Performance of Porous Ceramic Thermal Protection Systems at 9 km/s

NASA Technical Reports Server (NTRS)

Miller, Joshua E.; Bohl, W. E.; Foreman, C. D.; Christiansen, Eric L.; Davis, B. A.

2009-01-01

Porous-ceramic, thermal-protection-systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components and sensitive electronic components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s on ceramic tiles similar to those used on the Orbiter. These tiles have a porous-batting of nominally 8 lb/cubic ft alumina-fiber-enhanced-thermal-barrier (AETB8) insulating material coated with a damage-resistant, toughened-unipiece-fibrous-insulation (TUFI) layer.

WMAP Observatory Thermal Design and On-Orbit Thermal Performance

NASA Technical Reports Server (NTRS)

Glazer, Stuart D.; Brown, Kimberly D.; Michalek, Theodore J.; Ancarrow, Walter C.

2003-01-01

The Wilkinson Microwave Anisotropy Probe (WMAP) observatory, launched June 30, 2001, is designed to measure the cosmic microwave background radiation with unprecedented precision and accuracy while orbiting the second Lagrange point (L2). The instrument cold stage must be cooled passively to <95K, and systematic thermal variations in selected instrument components controlled to less than 0.5 mK (rms) per spin period. This paper describes the thermal design and testing of the WMAP spacecraft and instrument. Flight thermal data for key spacecraft and instrument components are presented from launch through the first year of mission operations. Effects of solar flux variation due to the Earth's elliptical orbit about the sun, surface thermo-optical property degradations, and solar flares on instrument thermal stability are discussed.

Research Technology

NASA Image and Video Library

2004-04-15

Pictured is a component of the Rocket Based Combined Cycle (RBCC) engine. This engine was designed to ultimately serve as the near term basis for Two Stage to Orbit (TSTO) air breathing propulsion systems and ultimately a Single Stage to Orbit (SSTO) air breathing propulsion system.

A Dual Power Law Distribution for the Stellar Initial Mass Function

NASA Astrophysics Data System (ADS)

Hoffmann, Karl Heinz; Essex, Christopher; Basu, Shantanu; Prehl, Janett

2018-05-01

We introduce a new dual power law (DPL) probability distribution function for the mass distribution of stellar and substellar objects at birth, otherwise known as the initial mass function (IMF). The model contains both deterministic and stochastic elements, and provides a unified framework within which to view the formation of brown dwarfs and stars resulting from an accretion process that starts from extremely low mass seeds. It does not depend upon a top down scenario of collapsing (Jeans) masses or an initial lognormal or otherwise IMF-like distribution of seed masses. Like the modified lognormal power law (MLP) distribution, the DPL distribution has a power law at the high mass end, as a result of exponential growth of mass coupled with equally likely stopping of accretion at any time interval. Unlike the MLP, a power law decay also appears at the low mass end of the IMF. This feature is closely connected to the accretion stopping probability rising from an initially low value up to a high value. This might be associated with physical effects of ejections sometimes (i.e., rarely) stopping accretion at early times followed by outflow driven accretion stopping at later times, with the transition happening at a critical time (therefore mass). Comparing the DPL to empirical data, the critical mass is close to the substellar mass limit, suggesting that the onset of nuclear fusion plays an important role in the subsequent accretion history of a young stellar object.

SIM PlanetQuest Key Project Precursor Observations to Detect Gas Giant Planets Around Young Stars

NASA Technical Reports Server (NTRS)

Tanner, Angelle; Beichman, Charles; Akeson, Rachel; Ghez, Andrea; Grankin, Konstantin N.; Herbst, William; Hillenbrand, Lynne; Huerta, Marcos; Konopacky, Quinn; Metchev, Stanimir;

Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b. First data from the GIARPS Commissioning

NASA Astrophysics Data System (ADS)

Carleo, I.; Benatti, S.; Lanza, A. F.; Gratton, R.; Claudi, R.; Desidera, S.; Mace, G. N.; Messina, S.; Sanna, N.; Sissa, E.; Ghedina, A.; Ghinassi, F.; Guerra, J.; Harutyunyan, A.; Micela, G.; Molinari, E.; Oliva, E.; Tozzi, A.; Baffa, C.; Baruffolo, A.; Bignamini, A.; Buchschacher, N.; Cecconi, M.; Cosentino, R.; Endl, M.; Falcini, G.; Fantinel, D.; Fini, L.; Fugazza, D.; Galli, A.; Giani, E.; González, C.; González-Álvarez, E.; González, M.; Hernandez, N.; Hernandez Diaz, M.; Iuzzolino, M.; Kaplan, K. F.; Kidder, B. T.; Lodi, M.; Malavolta, L.; Maldonado, J.; Origlia, L.; Ventura, H. Perez; Puglisi, A.; Rainer, M.; Riverol, L.; Riverol, C.; San Juan, J.; Scuderi, S.; Seemann, U.; Sokal, K. R.; Sozzetti, A.; Sozzi, M.

2018-05-01

Context. Stellar activity is currently challenging the detection of young planets via the radial velocity (RV) technique. Aims: We attempt to definitively discriminate the nature of the RV variations for the young active K5 star BD+20 1790, for which visible (VIS) RV measurements show divergent results on the existence of a substellar companion. Methods: We compare VIS data with high precision RVs in the near-infrared (NIR) range by using the GIANO-B and IGRINS spectrographs. In addition, we present for the first time simultaneous VIS-NIR observations obtained with GIARPS (GIANO-B and HARPS-N) at Telescopio Nazionale Galileo (TNG). Orbital RVs are achromatic, so the RV amplitude does not change at different wavelengths, while stellar activity induces wavelength-dependent RV variations, which are significantly reduced in the NIR range with respect to the VIS. Results: The NIR radial velocity measurements from GIANO-B and IGRINS show an average amplitude of about one quarter with respect to previously published VIS data, as expected when the RV jitter is due to stellar activity. Coeval multi-band photometry surprisingly shows larger amplitudes in the NIR range, explainable with a mixture of cool and hot spots in the same active region. Conclusions: In this work, the claimed massive planet around BD+20 1790 is ruled out by our data. We exploited the crucial role of multi-wavelength spectroscopy when observing young active stars: thanks to facilities like GIARPS that provide simultaneous observations, this method can reach its maximum potential.

A map of the large day-night temperature gradient of a super-Earth exoplanet.

PubMed

Demory, Brice-Olivier; Gillon, Michael; de Wit, Julien; Madhusudhan, Nikku; Bolmont, Emeline; Heng, Kevin; Kataria, Tiffany; Lewis, Nikole; Hu, Renyu; Krick, Jessica; Stamenković, Vlada; Benneke, Björn; Kane, Stephen; Queloz, Didier

2016-04-14

Over the past decade, observations of giant exoplanets (Jupiter-size) have provided key insights into their atmospheres, but the properties of lower-mass exoplanets (sub-Neptune) remain largely unconstrained because of the challenges of observing small planets. Numerous efforts to observe the spectra of super-Earths--exoplanets with masses of one to ten times that of Earth--have so far revealed only featureless spectra. Here we report a longitudinal thermal brightness map of the nearby transiting super-Earth 55 Cancri e (refs 4, 5) revealing highly asymmetric dayside thermal emission and a strong day-night temperature contrast. Dedicated space-based monitoring of the planet in the infrared revealed a modulation of the thermal flux as 55 Cancri e revolves around its star in a tidally locked configuration. These observations reveal a hot spot that is located 41 ± 12 degrees east of the substellar point (the point at which incident light from the star is perpendicular to the surface of the planet). From the orbital phase curve, we also constrain the nightside brightness temperature of the planet to 1,380 ± 400 kelvin and the temperature of the warmest hemisphere (centred on the hot spot) to be about 1,300 kelvin hotter (2,700 ± 270 kelvin) at a wavelength of 4.5 micrometres, which indicates inefficient heat redistribution from the dayside to the nightside. Our observations are consistent with either an optically thick atmosphere with heat recirculation confined to the planetary dayside, or a planet devoid of atmosphere with low-viscosity magma flows at the surface.

Confirming Variability in the Secondary Eclipse Depth of the Super-Earth 55 Cancri e

NASA Astrophysics Data System (ADS)

Tamburo, P.; Mandell, A.; Deming, D.; Garhart, E.

2018-05-01

We present a reanalysis of five transit and eight eclipse observations of the ultrashort-period super-Earth 55 Cancri e observed using the Spitzer Space Telescope during 2011–2013. We use pixel-level decorrelation to derive accurate transit and eclipse depths from the Spitzer data, and we perform an extensive error analysis. We focus on determining possible variability in the eclipse data, as was reported in Demory et al. From the transit data, we determine updated orbital parameters, yielding T 0 = 2,455,733.0037 ± 0.0002, P = 0.7365454 ± 0.0000003 days, i = 83.5 ± 1.°3, and R p = 1.89 ± 0.05 R ⊕. Our transit results are consistent with a constant depth, and we conclude that they are not variable. We find a significant amount of variability between the eight eclipse observations and confirm agreement with Demory et al. through a correlation analysis. We convert the eclipse measurements to brightness temperatures, and generate and discuss several heuristic models that explain the evolution of the planet’s eclipse depth versus time. The eclipses are best modeled by a year-to-year variability model, but variability on shorter timescales cannot be ruled out. The derived range of brightness temperatures can be achieved by a dark planet with inefficient heat redistribution intermittently covered over a large fraction of the substellar hemisphere by reflective grains, possibly indicating volcanic activity or cloud variability. This time-variable system should be observable with future space missions, both planned (JWST) and proposed (i.e., ARIEL).

Search for Exoplanets around Northern Circumpolar Stars. II. The Detection of Radial Velocity Variations in M Giant Stars HD 36384, HD 52030, and HD 208742

NASA Astrophysics Data System (ADS)

Lee, Byeong-Cheol; Jeong, Gwanghui; Park, Myeong-Gu; Han, Inwoo; Mkrtichian, David E.; Hatzes, Artie P.; Gu, Shenghong; Bai, Jinming; Lee, Sang-Min; Oh, Hyeong-Il; Kim, Kang-Min

2017-07-01

We present the detection of long-period RV variations in HD 36384, HD 52030, and HD 208742 by using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) for the precise radial velocity (RV) survey of about 200 northern circumpolar stars. Analyses of RV data, chromospheric activity indicators, and bisector variations spanning about five years suggest that the RV variations are compatible with planet or brown dwarf companions in Keplerian motion. However, HD 36384 shows photometric variations with a period very close to that of RV variations as well as amplitude variations in the weighted wavelet Z-transform (WWZ) analysis, which argues that the RV variations in HD 36384 are from the stellar pulsations. Assuming that the companion hypothesis is correct, HD 52030 hosts a companion with minimum mass 13.3 M Jup orbiting in 484 days at a distance of 1.2 au. HD 208742 hosts a companion of 14.0 M Jup at 1.5 au with a period of 602 days. All stars are located at the asymptotic giant branch (AGB) stage on the H-R diagram after undergoing the helium flash and leaving the giant clump.With stellar radii of 53.0 R ⊙ and 57.2 R ⊙ for HD 52030 and HD 208742, respectively, these stars may be the largest yet, in terms of stellar radius, found to host substellar companions. However, given possible RV amplitude variations and the fact that these are highly evolved stars, the planet hypothesis is not yet certain.

Demarcating Circulation Regimes of Synchronously Rotating Terrestrial Planets within the Habitable Zone

NASA Astrophysics Data System (ADS)

Haqq-Misra, Jacob; Wolf, Eric. T.; Joshi, Manoj; Zhang, Xi; Kopparapu, Ravi Kumar

2018-01-01

We investigate the atmospheric dynamics of terrestrial planets in synchronous rotation within the habitable zone of low-mass stars using the Community Atmosphere Model. The surface temperature contrast between the day and night hemispheres decreases with an increase in incident stellar flux, which is opposite the trend seen in gas giants. We define three dynamical regimes in terms of the equatorial Rossby deformation radius and the Rhines length. The slow rotation regime has a mean zonal circulation that spans from the day to the night sides, which occurs for planets around stars with effective temperatures of 3300–4500 K (rotation period > 20 days), with both the Rossby deformation radius and the Rhines length exceeding the planetary radius. Rapid rotators have a mean zonal circulation that partially spans a hemisphere and with banded cloud formation beneath the substellar point, which occurs for planets orbiting stars with effective temperatures of less than 3000 K (rotation period < 5 days), with the Rossby deformation radius less than the planetary radius. In between is the Rhines rotation regime, which retains a thermally direct circulation from the day side to the night side but also features midlatitude turbulence-driven zonal jets. Rhines rotators occur for planets around stars in the range of 3000–3300 K (rotation period ∼5–20 days), where the Rhines length is greater than the planetary radius but the Rossby deformation radius is less than the planetary radius. The dynamical state can be observationally inferred from a comparison of the morphologies of the thermal emission phase curves of synchronously rotating planets.

The Mass-Luminosity-Metallicity Relation for M Dwarfs

NASA Astrophysics Data System (ADS)

Mann, Andrew; Dupuy, Trent; Rizzuto, Aaron; Kraus, Adam; Gaidos, Eric; Ansdell, Megan

2018-01-01

One of the most powerful tools for stellar characterization is the mass-luminosity relation (MLR). In addition to its use for characterizing exoplanet hosts, the MLR for late-type stars is critical to measuring the stellar IMF, testing isochrones, and studies of Galactic archeology. However, existing MLRs do not fully account for metallicity effects, do not extend down to the substellar boundary, and are not precise enough to take full advantage of the impending arrival of Gaia parallaxes for millions of late-type stars. For two years we monitored 72 nearby M-dwarf astrometric binaries using adaptive optics and non-redundant aperture masking, with the goal of better constraining the MLR. We combined our astrometry with measurements from the literature and Keck archive to measure orbits, masses, and flux ratios of all binaries in JHK bands. In parallel, we obtained moderate-resolution NIR spectra of all binaries, from which we determine empirical metallicities for each system. We derived an updated MLR-metallicity relation that spans most of the M dwarf sequence (K5 to M7) and the metallicity range expected in the solar neighborhood (-0.5 < [M/H] +0.4). With this we explored the role metallicity plays in the MLR. With our revised relation and Gaia-precision parallaxes, it will soon be possible to calculate empirical masses of nearby M dwarfs to better than 2%, and future studies will enable us to extend our relation to more metal-poor stars and explore the role of youth and evolution of the MLR for M dwarfs.

LOCATING THE TRAILING EDGE OF THE CIRCUMBINARY RING IN THE KH 15D SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capelo, Holly L.; Herbst, William; Leggett, S. K.

2012-09-20

Following two years of complete occultation of both stars in the binary T Tauri star KH 15D by its opaque circumbinary ring, KH 15D has abruptly brightened again during apastron phases, reaching I = 15 mag. Here, we show that the brightening is accompanied by a change in spectral class from K6/K7 (the spectral class of star A) to {approx}K1, and a bluing of the system in V - I by about 0.3 mag. A radial velocity measurement confirms that, at apastron, we are now seeing direct light from star B, which is more luminous and of earlier spectral classmore » than star A. Evidently, the trailing edge of the occulting screen has just become tangent to one anse of star B's projected orbit. This confirms a prediction of the precession models, supports the view that the tilted ring is self-gravitating, and ushers in a new era of the system's evolution that should be accompanied by the same kind of dramatic phenomena observed from 1995 to 2009. It also promotes KH 15D from a single-lined to a double-lined eclipsing binary, greatly enhancing its value for testing pre-main-sequence models. The results of our study strengthen the case for truncation of the outer ring at around 4 AU by a sub-stellar object such as an extremely young giant planet. The system is currently at an optimal configuration for detecting the putative planet and we urge expedient follow-up observations.« less

Discovery of a stellar companion to the nearby solar-analogue HD 104304

NASA Astrophysics Data System (ADS)

Schnupp, C.; Bergfors, C.; Brandner, W.; Daemgen, S.; Fischer, D.; Marcy, G.; Henning, Th.; Hippler, S.; Janson, M.

2010-06-01

Context. Sun-like stars are promising candidates to host exoplanets and are often included in exoplanet surveys by radial velocity (RV) and direct imaging. In this paper we report on the detection of a stellar companion to the nearby solar-analogue star HD 104304, which previously was considered to host a planetary mass or brown dwarf companion. Aims: We searched for close stellar and substellar companions around extrasolar planet host stars with high angular resolution imaging to characterize planet formation environments. Methods: The detection of the stellar companion was achieved by high angular resolution measurements, using the “Lucky Imaging” technique at the ESO NTT 3.5 m with the AstraLux Sur instrument. We combined the results with VLT/NACO archive data, where the companion could also be detected. The results were compared to precise RV measurements of HD 104304, obtained at the Lick and Keck observatories from 2001-2010. Results: We confirmed common proper motion of the binary system. A spectral type of M4V of the companion and a mass of 0.21 M_⊙ was derived. Due to comparison of the data with RV measurements of the unconfirmed planet candidate listed in the Extrasolar Planets Encyclopaedia, we suggest that the discovered companion is the origin of the RV trend and that the inclination of the orbit of i≈35°explains the relatively small RV signal. Based on observations made with ESO Telescopes at the La Silla and Paranal Observatory under programme IDs 083.C-0145 and 084.C-0812, and on data obtained from the ESO Science Archive Facility.

AXISYMMETRIC SIMULATIONS OF HOT JUPITER–STELLAR WIND HYDRODYNAMIC INTERACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christie, Duncan; Arras, Phil; Li, Zhi-Yun

2016-03-20

Gas giant exoplanets orbiting at close distances to the parent star are subjected to large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of the planetary upper atmosphere and its interaction with the stellar wind are carried out to understand the possible flow regimes and how they affect the Lyα transmission spectrum. Following Tremblin and Chiang, charge exchange reactions are included to explore the role of energetic atoms as compared to thermal particles. In order to understand the role of the tail as compared to the leading edge of the planetary gas, the simulations were carried out undermore » axisymmetry, and photoionization and stellar wind electron impact ionization reactions were included to limit the extent of the neutrals away from the planet. By varying the planetary gas temperature, two regimes are found. At high temperature, a supersonic planetary wind is found, which is turned around by the stellar wind and forms a tail behind the planet. At lower temperatures, the planetary wind is shut off when the stellar wind penetrates inside where the sonic point would have been. In this regime mass is lost by viscous interaction at the boundary between planetary and stellar wind gases. Absorption by cold hydrogen atoms is large near the planetary surface, and decreases away from the planet as expected. The hot hydrogen absorption is in an annulus and typically dominated by the tail, at large impact parameter, rather than by the thin leading edge of the mixing layer near the substellar point.« less

A map of the large day-night temperature gradient of a super-Earth exoplanet

NASA Astrophysics Data System (ADS)

Demory, Brice-Olivier; Gillon, Michael; de Wit, Julien; Madhusudhan, Nikku; Bolmont, Emeline; Heng, Kevin; Kataria, Tiffany; Lewis, Nikole; Hu, Renyu; Krick, Jessica; Stamenković, Vlada; Benneke, Björn; Kane, Stephen; Queloz, Didier

2016-04-01

Over the past decade, observations of giant exoplanets (Jupiter-size) have provided key insights into their atmospheres, but the properties of lower-mass exoplanets (sub-Neptune) remain largely unconstrained because of the challenges of observing small planets. Numerous efforts to observe the spectra of super-Earths—exoplanets with masses of one to ten times that of Earth—have so far revealed only featureless spectra. Here we report a longitudinal thermal brightness map of the nearby transiting super-Earth 55 Cancri e (refs 4, 5) revealing highly asymmetric dayside thermal emission and a strong day-night temperature contrast. Dedicated space-based monitoring of the planet in the infrared revealed a modulation of the thermal flux as 55 Cancri e revolves around its star in a tidally locked configuration. These observations reveal a hot spot that is located 41 ± 12 degrees east of the substellar point (the point at which incident light from the star is perpendicular to the surface of the planet). From the orbital phase curve, we also constrain the nightside brightness temperature of the planet to 1,380 ± 400 kelvin and the temperature of the warmest hemisphere (centred on the hot spot) to be about 1,300 kelvin hotter (2,700 ± 270 kelvin) at a wavelength of 4.5 micrometres, which indicates inefficient heat redistribution from the dayside to the nightside. Our observations are consistent with either an optically thick atmosphere with heat recirculation confined to the planetary dayside, or a planet devoid of atmosphere with low-viscosity magma flows at the surface.

Spectra disentangling applied to the Hyades binary θ2 Tauri AB: new orbit, orbital parallax and component properties

NASA Astrophysics Data System (ADS)

Torres, K. B. V.; Lampens, P.; Frémat, Y.; Hensberge, H.; Lebreton, Y.; Škoda, P.

2011-01-01

Aims: θ^2 Tau is a detached and single-lined interferometric-spectroscopic binary as well as the most massive binary system of the Hyades cluster. The system revolves in an eccentric orbit with a periodicity of 140.7 days. Its light curve furthermore shows a complex pattern of δ Scuti-type pulsations. The secondary has a similar temperature but is less evolved and fainter than the primary. In addition, it is rotating more rapidly. Since the composite spectra are heavily blended, the direct extraction of radial velocities over the orbit of component B was hitherto unsuccessful. Our aim is to reveal the spectrum of the fainter component and its corresponding Doppler shifts in order to improve the accuracy of the physical properties of this important “calibrator” system. Methods: Using high-resolution spectroscopic data recently obtained with the Elodie (Observatoire de Haute-Provence, France) and Hermes (Roque de Los Muchachos, La Palma, Spain) spectrographs, and applying a spectra disentangling algorithm to three independent data sets including CfA spectra (Oak Ridge Observatory, USA), we derived an improved spectroscopic orbit. We next used a code based on simulated annealing and general least-squares minimization to refine the orbital solution by performing a combined astrometric-spectroscopic analysis based on the new spectroscopy and the long-baseline data from the Mark III optical interferometer. Results: As a result of the performed disentangling, and notwithstanding the high degree of blending, the velocity amplitude of the fainter component is obtained in a direct and objective way. Major progress based on this new determination includes an improved computation of the orbital parallax (still consistent with previous values). Our mass ratio is in good agreement with the older estimates of Peterson et al. (1991, 1993), but the mass of the primary is 15-25% higher than the more recent estimates by Torres et al. (1997) and Armstrong et al. (2006). Conclusions: The evolutionary status of both components is re-evaluated in the light of the revisited properties of θ^2 Tau AB. Due to the strategic position of the components in the turnoff region of the cluster, the new determinations imply stricter constraints for the age and the metallicity of the Hyades cluster. We conclude that the location of component B can be explained by current evolutionary models, but the location (and the status) of the more evolved component A is not trivially explained and requires a detailed abundance analysis of its disentangled spectrum. The improved accuracy (at the 2% level) on the stellar masses provides a useful basis for the comparison of the observed pulsation frequencies with suitable theoretical models. Based on observations obtained at the 1.93-m telescope of the Observatoire de Haute Provence, the 1.2-m Mercator telescope at the Roque de los Muchachos Observatory (in the framework of the Hermes Consortium) and the 1.5-m Wyeth telescope at Oak Ridge Observatory.Full Table 4 is only available in electronic form at http://www.aanda.org

The Updated Multiple Star Catalog

NASA Astrophysics Data System (ADS)

Tokovinin, Andrei

2018-03-01

The catalog of hierarchical stellar systems with three or more components is an update of the original 1997 version. For 2000 hierarchies, the new Multiple Star Catalog (MSC) provides distances, component masses and periods, and supplementary information (astrometry, photometry, identifiers, orbits, notes). The MSC content and format are explained, and its incompleteness and strong observational selection are stressed. Nevertheless, the MSC can be used for statistical studies and is a valuable source for planning observations of multiple stars. Rare classes of stellar hierarchies found in the MSC (with six or seven components, extremely eccentric orbits, planar and possibly resonant orbits, hosting planets) are briefly presented. High-order hierarchies have smaller velocity dispersion compared to triples and are often associated with moving groups. The paper concludes with an analysis of the ratio of periods and separations between inner and outer subsystems. In wide hierarchies, the ratio of semimajor axes, estimated statistically, is distributed between 3 and 300, with no evidence of dynamically unstable systems.

Fundamental parameters and origin of the very eccentric binary 41 Dra

NASA Astrophysics Data System (ADS)

Tokovinin, A.; Balega, Y. Y.; Pluzhnik, E. A.; Shatsky, N. I.; Gorynya, N. A.; Weigelt, G.

2003-10-01

The evolutionary status and origin of the most eccentric known binary in a quadruple system, 41 Dra (e=0.9754, period 3.413 yr), are discussed. New observations include the much improved combined speckle-interferometric orbit, resolved photometry of the components and their spectroscopic analysis. The age of the system is 2.5 +/- 0.2 Gyr; all four components are likely coeval. The high eccentricity of the orbit together with known age and masses provide a constraint on the tidal circularization theory: it seems that the eccentric orbit survived because the convective zones of the F-type dwarfs were very thin. Now as the components of 41 Dra are leaving the Main Sequence, their increased interaction at each periastron passage may result in detectable changes in period and eccentricity. Tables 1, 2, and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/409/245

Measuring Fundamental Parameters of Substellar Objects. I. Surface Gravities

NASA Astrophysics Data System (ADS)

Mohanty, Subhanjoy; Basri, Gibor; Jayawardhana, Ray; Allard, France; Hauschildt, Peter; Ardila, David

2004-07-01

We present an analysis of high-resolution optical spectra for a sample of very young, mid- to late-M, low-mass stellar and substellar objects: 11 in the Upper Scorpius association, and two (GG Tau Ba and Bb) in the Taurus star-forming region. Effective temperatures and surface gravities are derived from a multiple-feature spectral analysis using TiO, Na I, and K I, through comparison with the latest synthetic spectra. We show that these spectral diagnostics complement each other, removing degeneracies with temperature and gravity in the behavior of each. In combination, they allow us to determine temperature to within 50 K and gravity to within 0.25 dex, in very cool young objects. Our high-resolution spectral analysis does not require extinction estimates. Moreover, it yields temperatures and gravities independent of theoretical evolutionary models (although our estimates do depend on the synthetic spectral modeling). We find that our gravities for most of the sample agree remarkably well with the isochrone predictions for the likely cluster ages. However, discrepancies appear in our coolest targets: these appear to have significantly lower gravity (by up to 0.75 dex) than our hotter objects, even though our entire sample covers a relatively narrow range in effective temperature (~300 K). This drop in gravity is also implied by intercomparisons of the data alone, without recourse to synthetic spectra. We consider, and argue against, dust opacity, cool stellar spots, or metallicity differences leading to the observed spectral effects; a real decline in gravity is strongly indicated. Such gravity variations are contrary to the predictions of the evolutionary tracks, causing improbably low ages to be inferred from the tracks for our coolest targets. Through a simple consideration of contraction timescales, we quantify the age errors introduced into the tracks through the particular choice of initial conditions and demonstrate that they can be significant for low-mass objects that are only a few megayears old. However, we also find that these errors appear insufficient to explain the magnitude of the age offsets in our lowest gravity targets. We venture that this apparent age offset may arise from evolutionary model uncertainties related to accretion, deuterium burning and/or convection effects. Finally, when combined with photometry and distance information, our technique for deriving surface gravities and effective temperatures provides a way of obtaining masses and radii for substellar objects independent of evolutionary models; radius and mass determinations are presented in Paper II.

HEARTBEAT STARS: SPECTROSCOPIC ORBITAL SOLUTIONS FOR SIX ECCENTRIC BINARY SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smullen, Rachel A.; Kobulnicky, Henry A., E-mail: rsmullen@email.arizona.edu

2015-08-01

We present multi-epoch spectroscopy of “heartbeat stars,” eccentric binaries with dynamic tidal distortions and tidally induced pulsations originally discovered with the Kepler satellite. Optical spectra of six known heartbeat stars using the Wyoming Infrared Observatory 2.3 m telescope allow measurement of stellar effective temperatures and radial velocities from which we determine orbital parameters including the periods, eccentricities, approximate mass ratios, and component masses. These spectroscopic solutions confirm that the stars are members of eccentric binary systems with eccentricities e > 0.34 and periods P = 7–20 days, strengthening conclusions from prior works that utilized purely photometric methods. Heartbeat stars inmore » this sample have A- or F-type primary components. Constraints on orbital inclinations indicate that four of the six systems have minimum mass ratios q = 0.3–0.5, implying that most secondaries are probable M dwarfs or earlier. One system is an eclipsing, double-lined spectroscopic binary with roughly equal-mass mid-A components (q = 0.95), while another shows double-lined behavior only near periastron, indicating that the F0V primary has a G1V secondary (q = 0.65). This work constitutes the first measurements of the masses of secondaries in a statistical sample of heartbeat stars. The good agreement between our spectroscopic orbital elements and those derived using a photometric model support the idea that photometric data are sufficient to derive reliable orbital parameters for heartbeat stars.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuang Quntao; Gao Xun; Yu Qingjuan, E-mail: yuqj@pku.edu.cn

In this paper, we study possible signatures of binary planets or exomoons on the Rossiter-McLaughlin (R-M) effect. Our analyses show that the R-M effect for a binary planet or an exomoon during its complete transit phase can be divided into two parts. The first is the conventional one similar to the R-M effect from the transit of a single planet, of which the mass and the projected area are the combinations of the binary components; the second is caused by the orbital rotation of the binary components, which may add a sine- or linear-mode deviation to the stellar radial velocitymore » curve. We find that the latter effect can be up to several ten m s{sup -1}. Our numerical simulations as well as analyses illustrate that the distribution and dispersion of the latter effects obtained from multiple transit events can be used to constrain the dynamical configuration of the binary planet, such as how the inner orbit of the binary planet is inclined to its orbit rotating around the central star. We find that the signatures caused by the orbital rotation of the binary components are more likely to be revealed if the two components of a binary planet have different masses and mass densities, especially if the heavy one has a high mass density and the light one has a low density. Similar signatures on the R-M effect may also be revealed in a hierarchical triple star system containing a dark compact binary and a tertiary star.« less

The Orbiter camera payload system's large-format camera and attitude reference system

NASA Technical Reports Server (NTRS)

Schardt, B. B.; Mollberg, B. H.

1985-01-01

The Orbiter camera payload system (OCPS) is an integrated photographic system carried into earth orbit as a payload in the Space Transportation System (STS) Orbiter vehicle's cargo bay. The major component of the OCPS is a large-format camera (LFC), a precision wide-angle cartographic instrument capable of producing high-resolution stereophotography of great geometric fidelity in multiple base-to-height ratios. A secondary and supporting system to the LFC is the attitude reference system (ARS), a dual-lens stellar camera array (SCA) and camera support structure. The SCA is a 70 mm film system that is rigidly mounted to the LFC lens support structure and, through the simultaneous acquisition of two star fields with each earth viewing LFC frame, makes it possible to precisely determine the pointing of the LFC optical axis with reference to the earth nadir point. Other components complete the current OCPS configuration as a high-precision cartographic data acquisition system. The primary design objective for the OCPS was to maximize system performance characteristics while maintaining a high level of reliability compatible with rocket launch conditions and the on-orbit environment. The full OCPS configuration was launched on a highly successful maiden voyage aboard the STS Orbiter vehicle Challenger on Oct. 5, 1984, as a major payload aboard the STS-41G mission.

Basic features of the STS/Spacelab vibration environment

NASA Technical Reports Server (NTRS)

Baugher, Charles R.; Ramachandran, N.

1994-01-01

The Space Shuttle acceleration environment is characterized. The acceleration environment is composed of a residual or quasi-steady component and higher frequency components induced by vehicle structural modes and the operation of onboard machinery. Quasi-steady accelerations are generally due to atmospheric drag, gravity gradient effects, and rotational forces. These accelerations tend to vary with the orbital frequency (approx. 10(exp -4) Hz) and have magnitudes less than or equal to 10(exp -6) g(sub 0) (where 1 g(sub 0) is terrestrial gravity). Higher frequency g-jitter is characterized by oscillatory disturbances in the 1-100 Hz range and transient components. Oscillatory accelerations are related to the response of large flexible structures like antennae, the Spacelab module, and the Orbiter itself, and to the operation of rotating machinery. The Orbiter structural modes in the 1-10 Hz range, are excited by oscillatory and transient disturbances and tend to dominate the energy spectrum of the acceleration environment. A comparison of the acceleration measurements from different Space Shuttle missions reveals the characteristic signature of the structural modes of the Orbiter overlaid with mission specific hardware induced disturbances and their harmonics. Transient accelerations are usually attributed to crew activity and Orbiter thruster operations. During crew sleep periods, the acceleration levels are typically on the order of 10(exp -6) g(sub 0) (1 micro-g). Crew work and exercise tend to raise the accelerations to the 10(exp -3) g(sub 0) (1 milli-g) level. Vernier reaction control system firings tend to cause accelerations of 10(exp -4) g(sub 0), while primary reaction control system and Orbiter maneuvering system firings cause accelerations as large as 10(exp -2) g(sub 0). Vibration isolation techniques (both active and passive systems) used during crew exercise have been shown to significantly reduce the acceleration magnitudes.

Precision Orbit of δ Delphini and Prospects for Astrometric Detection of Exoplanets

NASA Astrophysics Data System (ADS)

Gardner, Tyler; Monnier, John D.; Fekel, Francis C.; Williamson, Mike; Duncan, Douglas K.; White, Timothy R.; Ireland, Michael; Adams, Fred C.; Barman, Travis; Baron, Fabien; ten Brummelaar, Theo; Che, Xiao; Huber, Daniel; Kraus, Stefan; Roettenbacher, Rachael M.; Schaefer, Gail; Sturmann, Judit; Sturmann, Laszlo; Swihart, Samuel J.; Zhao, Ming

2018-03-01

Combining visual and spectroscopic orbits of binary stars leads to a determination of the full 3D orbit, individual masses, and distance to the system. We present a full analysis of the evolved binary system δ Delphini using astrometric data from the MIRC and PAVO instruments on the CHARA long-baseline interferometer, 97 new spectra from the Fairborn Observatory, and 87 unpublished spectra from the Lick Observatory. We determine the full set of orbital elements for δ Del, along with masses of 1.78 ± 0.07 M ⊙ and 1.62 ± 0.07 M ⊙ for each component, and a distance of 63.61 ± 0.89 pc. These results are important in two contexts: for testing stellar evolution models and for defining the detection capabilities for future planet searches. We find that the evolutionary state of this system is puzzling, as our measured flux ratios, radii, and masses imply a ∼200 Myr age difference between the components, using standard stellar evolution models. Possible explanations for this age discrepancy include mass transfer scenarios with a now-ejected tertiary companion. For individual measurements taken over a span of two years, we achieve <10 μas precision on the differential position with 10 minute observations. The high precision of our astrometric orbit suggests that exoplanet detection capabilities are within reach of MIRC at CHARA. We compute exoplanet detection limits around δ Del and conclude that, if this precision is extended to wider systems, we should be able to detect most exoplanets >2 M J on orbits >0.75 au around individual components of hot binary stars via differential astrometry.

MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS-AURIGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraus, Adam L.; Ireland, Michael J.; Martinache, Frantz

2011-04-10

We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new binary companions to primary stars with masses of 0.25-2.5 M{sub sun}, raising the total number of binary pairs (including components of high-order multiples) with separations of 3-5000 AU to 90. We find that {approx}2/3-3/4 of all Taurus members are multiple systems of two or more stars, while the other {approx}1/4-1/3 appear to have formed as single stars; the distribution of high-order multiplicity suggests thatmore » fragmentation into a wide binary has no impact on the subsequent probability that either component will fragment again. The separation distribution for solar-type stars (0.7-2.5 M{sub sun}) is nearly log-flat over separations of 3-5000 AU, but lower-mass stars (0.25-0.7 M{sub sun}) show a paucity of binary companions with separations of {approx}>200 AU. Across this full mass range, companion masses are well described with a linear-flat function; all system mass ratios (q = M{sub B} /M{sub A} ) are equally probable, apparently including substellar companions. Our results are broadly consistent with the two expected modes of binary formation (free-fall fragmentation on large scales and disk fragmentation on small scales), but the distributions provide some clues as to the epochs at which the companions are likely to form.« less

Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data

NASA Technical Reports Server (NTRS)

Deutschmann, Julie; Bar-Itzhack, Itzhack

1997-01-01

A single, augmented extended Kalman filter (EKF) which simultaneously and autonomously estimates spacecraft attitude and orbit was developed and tested with simulated and real magnetometer and rate data. Since the earth's magnetic field is a function of time and position, and since time is accurately known, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft's orbit, are a function of orbit and attitude errors. These differences can be used to estimate the orbit and attitude. The test results of the EKF with magnetometer and gyro data from three NASA satellites are presented and evaluated.

Proton Upset Monte Carlo Simulation

NASA Technical Reports Server (NTRS)

O'Neill, Patrick M.; Kouba, Coy K.; Foster, Charles C.

2009-01-01

The Proton Upset Monte Carlo Simulation (PROPSET) program calculates the frequency of on-orbit upsets in computer chips (for given orbits such as Low Earth Orbit, Lunar Orbit, and the like) from proton bombardment based on the results of heavy ion testing alone. The software simulates the bombardment of modern microelectronic components (computer chips) with high-energy (.200 MeV) protons. The nuclear interaction of the proton with the silicon of the chip is modeled and nuclear fragments from this interaction are tracked using Monte Carlo techniques to produce statistically accurate predictions.

Temperature dependence of spin-orbit torques in W/CoFeB bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skowroński, Witold, E-mail: skowron@agh.edu.pl; Cecot, Monika; Kanak, Jarosław

We report on the temperature variation of spin-orbit torques in perpendicularly magnetized W/CoFeB bilayers. Harmonic Hall voltage measurements in perpendicularly magnetized CoFeB reveal increased longitudinal and transverse effective magnetic field components at low temperatures. The damping-like spin-orbit torque reaches an efficiency of 0.55 at 19 K. Scanning transmission electron microscopy and X-ray reflectivity measurements indicate that considerable interface mixing between W and CoFeB may be responsible for strong spin-orbit interactions.

Autonomous Aerobraking Using Thermal Response Surface Analysis

NASA Technical Reports Server (NTRS)

Prince, Jill L.; Dec, John A.; Tolson, Robert H.

2007-01-01

Aerobraking is a proven method of significantly increasing the science payload that can be placed into low Mars orbits when compared to an all propulsive capture. However, the aerobraking phase is long and has mission cost and risk implications. The main cost benefit is that aerobraking permits the use of a smaller and cheaper launch vehicle, but additional operational costs are incurred during the long aerobraking phase. Risk is increased due to the repeated thermal loading of spacecraft components and the multiple attitude and propulsive maneuvers required for successful aerobraking. Both the cost and risk burdens can be significantly reduced by automating the aerobraking operations phase. All of the previous Mars orbiter missions that have utilized aerobraking have increasingly relied on onboard calculations during aerobraking. Even though the temperature of spacecraft components has been the limiting factor, operational methods have relied on using a surrogate variable for mission control. This paper describes several methods, based directly on spacecraft component maximum temperature, for autonomously predicting the subsequent aerobraking orbits and prescribing apoapsis propulsive maneuvers to maintain the spacecraft within specified temperature limits. Specifically, this paper describes the use of thermal response surface analysis in predicting the temperature of the spacecraft components and the corresponding uncertainty in this temperature prediction.

Weight minimization of structural components for launch in space shuttle

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Gendy, Atef S.; Hopkins, Dale A.; Berke, Laszlo

1994-01-01

Minimizing the weight of structural components of the space station launched into orbit in a space shuttle can save cost, reduce the number of space shuttle missions, and facilitate on-orbit fabrication. Traditional manual design of such components, although feasible, cannot represent a minimum weight condition. At NASA Lewis Research Center, a design capability called CometBoards (Comparative Evaluation Test Bed of Optimization and Analysis Routines for the Design of Structures) has been developed especially for the design optimization of such flight components. Two components of the space station - a spacer structure and a support system - illustrate the capability of CometBoards. These components are designed for loads and behavior constraints that arise from a variety of flight accelerations and maneuvers. The optimization process using CometBoards reduced the weights of the components by one third from those obtained with traditional manual design. This paper presents a brief overview of the design code CometBoards and a description of the space station components, their design environments, behavior limitations, and attributes of their optimum designs.

Photochemically Etched Construction Technology Developed for Digital Xenon Feed Systems

NASA Technical Reports Server (NTRS)

Otsap, Ben; Cardin, Joseph; Verhey, Timothy R.; Rawlin, Vincent K.; Mueller, Juergen; Aadlund, Randall; Kay, Robert; Andrews, Michael

2005-01-01

Electric propulsion systems are quickly emerging as attractive options for primary propulsion in low Earth orbit, in geosynchronous orbit, and on interplanetary spacecraft. The driving force behind the acceptance of these systems is the substantial reduction in the propellant mass that can be realized. Unfortunately, system designers are often forced to utilize components designed for chemical propellants in their electric systems. Although functionally acceptable, these relatively large, heavy components are designed for the higher pressures and mass flow rates required by chemical systems. To fully realize the benefits of electric propulsion, researchers must develop components that are optimized for the low flow rates, critical leakage needs, low pressures, and limited budgets of these emerging systems.

Orbital Elements and Stellar Parameters of the Active Binary UX Arietis

NASA Astrophysics Data System (ADS)

Hummel, C. A.; Monnier, J. D.; Roettenbacher, R. M.; Torres, G.; Henry, G. W.; Korhonen, H.; Beasley, A.; Schaefer, G. H.; Turner, N. H.; Ten Brummelaar, T.; Farrington, C. D.; Sturmann, J.; Sturmann, L.; Baron, F.; Kraus, S.

2017-08-01

Stellar activity observed as large surface spots, radio flares, or emission lines is often found in binary systems. UX Arietis exhibits these signs of activity, originating on the K0 subgiant primary component. Our aim is to resolve the binary, measure the orbital motion, and provide accurate stellar parameters such as masses and luminosities to aid in the interpretation of the observed phenomena. Using the CHARA six-telescope optical long-baseline array on Mount Wilson, California, we obtained amplitudes and phases of the interferometric visibility on baselines up to 330 m in length, resolving the two components of the binary. We reanalyzed archival Center for Astrophysics spectra to disentangle the binary component spectra and the spectrum of the third component, which was resolved by speckle interferometry. We also obtained new spectra with the Nordic Optical Telescope, and we present new photometric data that we use to model stellar surface spot locations. Both interferometric visibilities and spectroscopic radial velocities are modeled with a spotted primary stellar surface using the Wilson-Devinney code. We fit the orbital elements to the apparent orbit and radial velocity data to derive the distance (52.1 ± 0.8 pc) and stellar masses ({M}{{P}}=1.30+/- 0.06 {M}⊙ , {M}{{S}}=1.14+/- 0.06 {M}⊙ ). The radius of the primary can be determined to be {R}{{P}}=5.6+/- 0.1 {R}⊙ and that of the secondary to be {R}{{S}}=1.6+/- 0.2 {R}⊙ . The equivalent spot coverage of the primary component was found to be 62% with an effective temperature 20% below that of the unspotted surface.

Rocket Based Combined Cycle (RBCC) engine inlet

NASA Technical Reports Server (NTRS)

2004-01-01

Pictured is a component of the Rocket Based Combined Cycle (RBCC) engine. This engine was designed to ultimately serve as the near term basis for Two Stage to Orbit (TSTO) air breathing propulsion systems and ultimately a Single Stage to Orbit (SSTO) air breathing propulsion system.

Two-component relativistic coupled-cluster methods using mean-field spin-orbit integrals

NASA Astrophysics Data System (ADS)

Liu, Junzi; Shen, Yue; Asthana, Ayush; Cheng, Lan

2018-01-01

A novel implementation of the two-component spin-orbit (SO) coupled-cluster singles and doubles (CCSD) method and the CCSD augmented with the perturbative inclusion of triple excitations [CCSD(T)] method using mean-field SO integrals is reported. The new formulation of SO-CCSD(T) features an atomic-orbital-based algorithm for the particle-particle ladder term in the CCSD equation, which not only removes the computational bottleneck associated with the large molecular-orbital integral file but also accelerates the evaluation of the particle-particle ladder term by around a factor of 4 by taking advantage of the spin-free nature of the instantaneous electron-electron Coulomb interaction. Benchmark calculations of the SO splittings for the thallium atom and a set of diatomic 2Π radicals as well as of the bond lengths and harmonic frequencies for a set of closed-shell diatomic molecules are presented. The basis-set and core-correlation effects in the calculations of these properties have been carefully analyzed.

Perturbative treatment of spin-orbit-coupling within spin-free exact two-component theory using equation-of-motion coupled-cluster methods

NASA Astrophysics Data System (ADS)

Cheng, Lan; Wang, Fan; Stanton, John F.; Gauss, Jürgen

2018-01-01

A scheme is reported for the perturbative calculation of spin-orbit coupling (SOC) within the spin-free exact two-component theory in its one-electron variant (SFX2C-1e) in combination with the equation-of-motion coupled-cluster singles and doubles method. Benchmark calculations of the spin-orbit splittings in 2Π and 2P radicals show that the accurate inclusion of scalar-relativistic effects using the SFX2C-1e scheme extends the applicability of the perturbative treatment of SOC to molecules that contain heavy elements. The contributions from relaxation of the coupled-cluster amplitudes are shown to be relatively small; significant contributions from correlating the inner-core orbitals are observed in calculations involving third-row and heavier elements. The calculation of term energies for the low-lying electronic states of the PtH radical, which serves to exemplify heavy transition-metal containing systems, further demonstrates the quality that can be achieved with the pragmatic approach presented here.

Drifting Recovery Base Concept for GEO Derelict Object Capture

NASA Technical Reports Server (NTRS)

Bacon, John B.

2009-01-01

Over 250 objects hover within 6 m/sec of perfect geostationary orbit. Over half of these objects lie within 0.1 m/sec of the GEO velocity. Such items have 62% of the total velocity required to achieve Earth gravitational escape. A conceptual architecture is proposed to clean this orbit area of derelict objects while providing a demonstration mission for many facets of future asteroid mining operations. These near-GEO objects average nearly 2000kg each, consisting of (typically functioning) power systems, batteries, and large quantities of components and raw aerospace-grade refined materials. Such a demonstration collection system could capture, collect and remove all GEO derelict objects in an international effort to create a depot of components and of aerospace-grade raw materials--with a total mass greater than that of the International Space Station--as a space scrap depot ready for transfer to lunar or Mars orbit, using only two heavy-lift launches and 2-3 years of on-orbit operations.

The Star, the Dwarf and the Planet

NASA Astrophysics Data System (ADS)

2006-10-01

Astronomers have detected a new faint companion to the star HD 3651, already known to host a planet. This companion, a brown dwarf, is the faintest known companion of an exoplanet host star imaged directly and one of the faintest T dwarfs detected in the Solar neighbourhood so far. The detection yields important information on the conditions under which planets form. "Such a system is an interesting example that might prove that planets and brown dwarfs can form around the same star", said Markus Mugrauer, lead author of the paper presenting the discovery. ESO PR Photo 39a/06 ESO PR Photo 39a/06 The Companion to HD 3651 HD 3651 is a star slightly less massive than the Sun, located 36 light-years away in the constellation Pisces (the "Fish"). For several years, it has been known to harbour a planet less massive than Saturn, sitting closer to its parent star than Mercury is from the Sun: the planet accomplishes a full orbit in 62 days. Mugrauer and his colleagues first spotted the faint companion in 2003 on images from the 3.8-m United Kingdom Infrared Telescope (UKIRT) in Hawaii. Observations in 2004 and 2006 using ESO's 3.6 m New Technology Telescope (NTT) at La Silla provided the crucial confirmation that the speck of light is not a spurious background star, but indeed a true companion. The newly found companion, HD 3651B, is 16 times further away from HD 3651 than Neptune is from the Sun. HD 3651B is the dimmest directly imaged companion of an exoplanet host star. Furthermore, as it is not detected on the photographic plates of the Palomar All Sky Survey, the companion must be even fainter in the visible spectral range than in the infrared, meaning it is a very cool low-mass sub-stellar object. Comparing its characteristics with theoretical models, the astronomers infer that the object has a mass between 20 and 60 Jupiter masses, and a temperature between 500 and 600 degrees Celsius. It is thus ten times colder and 300 000 less luminous than the Sun. These properties place it in the category of cool T-type brown dwarfs. ESO PR Photo 38b/06 ESO PR Photo 39b/06 The Relative Position of the Companion to HD 3651 "Due to their faintness even in the infrared, these cool T dwarfs are very difficult to find", said Mugrauer. "Only two other brown dwarfs with similar brightness are presently known. Their study will provide important insights into the atmospheric properties of cool sub-stellar objects." More than 170 stars are currently known to host exoplanets. In some cases, these stars were also found to have one or several stellar companions, showing that planet formation can also take place in a dynamically more complex environment than our own Solar System where planet formation occurred around an isolated single star. In 2001, Mugrauer and his colleagues started an observational programme to find out whether exoplanet host stars are single or married. In this programme, known exoplanet host stars are systematically imaged at two different epochs, at least several months apart. True companions can be distinguished from coincidental background objects as only they move together with the stars over time. With this effective search strategy several new companions of exoplanet host stars have been detected. Most of the detected companions are low-mass stars in the same evolutionary state as the Sun. In two cases, however, the astronomers found the companions to be white dwarfs, that is, stars at the end of their life. These intriguing systems bear evidence that planets can even survive the troubled last moments in the life of a nearby star. The planet host star HD 3651 is thus surrounded by two sub-stellar objects. The planet, HD 3651b, is very close, while the newly found brown dwarf companion revolves around the star 1500 times farther away than the planet. This system is the first imaged example that planets and brown dwarfs can form around the same star.

Photometry of the long period dwarf nova GY Hya

NASA Astrophysics Data System (ADS)

Bruch, Albert; Monard, Berto

2017-08-01

Although comparatively bright, the cataclysmic variable GY Hya has not attracted much attention in the past. As part of a project to better characterize such systems photometrically, we observed light curves in white light, each spanning several hours, at Bronberg Observatory, South Africa, in 2004 and 2005, and at the Observatório do Pico dos Dias, Brazil, in 2014 and 2016. These data permit to study orbital modulations and their variations from season to season. The orbital period, already known from spectroscopic observations of Peters and Thorstensen (2005), is confirmed through strong ellipsoidal variations of the mass donor star in the system and the presence of eclipses of both components. A refined period of 0.34723972 (6) days and revised ephemeries are derived. Seasonal changes in the average orbital light curve can qualitatively be explained by variations of the contribution of a hot spot to the system light together with changes of the disk radius. The amplitude of the ellipsoidal variations and the eclipse contact phases permit to put some constraints on the mass ratio, orbital inclination and the relative brightness of the primary and secondary components. There are some indications that the disk radius during quiescence, expressed in units of the component separation, is smaller than in other dwarf novae.

PHOTOMETRIC, SPECTROSCOPIC, AND ORBITAL PERIOD STUDY OF THREE EARLY-TYPE SEMI-DETACHED SYSTEMS: XZ AQL, UX HER, AND AT PEG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zola, S.; Baştürk, Ö.; Şenavcı, H. V.

2016-08-01

In this paper, we present a combined photometric, spectroscopic, and orbital period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and AT Peg. As a result, we have derived the absolute parameters of their components and, on that basis, we discuss their evolutionary states. Furthermore, we compare their parameters with those of other binary systems and with theoretical models. An analysis of all available up-to-date times of minima indicated that all three systems studied here show cyclic orbital changes; their origin is discussed in detail. Finally, we performed a frequency analysis for possible pulsational behavior, and asmore » a result we suggest that XZ Aql hosts a δ Scuti component.« less

A three-dimensional orbit for the binary star Alpha Andromedae

NASA Astrophysics Data System (ADS)

Branham, Richard L., Jr.

2017-01-01

Stars that are both spectroscopic and optical binaries present a means to determine simultaneously the masses of the components and the distance of the system independent of trigonometric parallax. Alpha Andromedae (Alpheratz) represents such a system and, moreover, the primary is the brightest of the mercury-manganese stars. An orbit, based on 42 interferometric observations and 378 radial velocities, is calculated to solve for 10 parameters: the six coefficients of the apparent ellipse, the constant of areal velocity, the systemic velocity, and the semi-amplitudes. From these, one calculates the orbit of the binary, its period and time of periastron passage, the masses of the components, and the distance of the system. The dynamical parallax does not differ greatly from the trigonometric parallax found from Hipparcos.

The binary Asteroid 22 Kalliope: Linus orbit determination on the basis of speckle interferometric observations

NASA Astrophysics Data System (ADS)

Sokova, I. A.; Sokov, E. N.; Roschina, E. A.; Rastegaev, D. A.; Kiselev, A. A.; Balega, Yu. Yu.; Gorshanov, D. L.; Malogolovets, E. V.; Dyachenko, V. V.; Maksimov, A. F.

2014-07-01

In this paper we present the orbital elements of Linus satellite of 22 Kalliope asteroid. Orbital element determination is based on the speckle interferometry data obtained with the 6-m BTA telescope operated by SAO RAS. We processed 9 accurate positions of Linus orbiting around the main component of 22 Kalliope between 10 and 16 December, 2011. In order to determine the orbital elements of the Linus we have applied the direct geometric method. The formal errors are about 5 mas. This accuracy makes it possible to study the variations of the Linus orbital elements influenced by different perturbations over the course of time. Estimates of six classical orbital elements, such as the semi-major axis of the Linus orbit a = 1109 ± 6 km, eccentricity e = 0.016 ± 0.004, inclination i = 101° ± 1° to the ecliptic plane and others, are presented in this work.

Towards a Fundamental Understanding of Short Period Eclipsing Binary Systems Using Kepler Data

NASA Astrophysics Data System (ADS)

Prsa, Andrej

Kepler's ultra-high precision photometry is revolutionizing stellar astrophysics. We are seeing intrinsic phenomena on an unprecedented scale, and interpreting them is both a challenge and an exciting privilege. Eclipsing binary stars are of particular significance for stellar astrophysics because precise modeling leads to fundamental parameters of the orbiting components: masses, radii, temperatures and luminosities to better than 1-2%. On top of that, eclipsing binaries are ideal physical laboratories for studying other physical phenomena, such as asteroseismic properties, chromospheric activity, proximity effects, mass transfer in close binaries, etc. Because of the eclipses, the basic geometry is well constrained, but a follow-up spectroscopy is required to get the dynamical masses and the absolute scale of the system. A conjunction of Kepler photometry and ground- based spectroscopy is a treasure trove for eclipsing binary star astrophysics. This proposal focuses on a carefully selected set of 100 short period eclipsing binary stars. The fundamental goal of the project is to study the intrinsic astrophysical effects typical of short period binaries in great detail, utilizing Kepler photometry and follow-up spectroscopy to devise a robust and consistent set of modeling results. The complementing spectroscopy is being secured from 3 approved and fully funded programs: the NOAO 4-m echelle spectroscopy at Kitt Peak (30 nights; PI Prsa), the 10- m Hobby-Eberly Telescope high-resolution spectroscopy (PI Mahadevan), and the 2.5-m Sloan Digital Sky Survey III spectroscopy (PI Mahadevan). The targets are prioritized by the projected scientific yield. Short period detached binaries host low-mass (K- and M- type) components for which the mass-radius relationship is sparsely populated and still poorly understood, as the radii appear up to 20% larger than predicted by the population models. We demonstrate the spectroscopic detection viability in the secondary-to-primary light ratio regime of ~1-2% for the circumbinary host system Kepler-16. Semi-detached binaries are ideal targets to study the dynamical processes such as mass flow and accretion, and the associated thermal processes such as intensity variation due to distortion of the lobe-filling component and material inflow collisions with accretion disks. Overcontact binaries are very abundant, yet their evolution and radiative properties are poorly understood and conflicting theories exist to explain their population frequency and structure. In addition, we will measure eclipse timing variations for all program binaries that attest to the presence of perturbing third bodies (stellar and substellar!) or dynamical interaction between the components. By a dedicated, detailed, manual modeling of these sets of targets, we will be able to use Kepler's ultra-high precision photometry to a rewarding scientific end. Thanks to the unprecedented quality of Kepler data, this will be a highly focused effort that maximizes the scientific yield and the reliability of the results. Our team has ample experience dealing with Kepler data (PI Prsa serves as chair of the Eclipsing Binary Working Group in the Kepler Science Team), spectroscopic follow-up (Co-Is Mahadevan and Bender both have experience with radial velocity instrumentation and large spectroscopic surveys), and eclipsing binary modeling (PI Prsa and Co-I Devinney both have a long record of theoretical and computational development of modeling tools). The bulk of funding we are requesting is for two postdoctoral research fellows to conduct this work at 0.5 FTE/year each, for the total of 2 years.

Orbital transfer rocket engine technology 7.5K-LB thrust rocket engine preliminary design

NASA Technical Reports Server (NTRS)

Harmon, T. J.; Roschak, E.

1993-01-01

A preliminary design of an advanced LOX/LH2 expander cycle rocket engine producing 7,500 lbf thrust for Orbital Transfer vehicle missions was completed. Engine system, component and turbomachinery analysis at both on design and off design conditions were completed. The preliminary design analysis results showed engine requirements and performance goals were met. Computer models are described and model outputs are presented. Engine system assembly layouts, component layouts and valve and control system analysis are presented. Major design technologies were identified and remaining issues and concerns were listed.

The effect of oblateness and gravity darkening on the radiation driving in winds from rapidly rotating B stars

NASA Technical Reports Server (NTRS)

Cranmer, Steven R.; Owocki, Stanley P.

1995-01-01

We calculate the radiative driving force for winds around rapidly rotating oblate B stars, and we estimate the impact these forces should have on the production of a wind compressed disk. The effects of limb darkening, gravity darkening, oblateness, and an arbitrary wind velocity field are included in the computation of vector 'oblate finite disk' (OFD) factors, which depend on both radius and colatitude in the wind. The impact of limb darkening alone, with or without rotation, can increase the mass loss by as much as 10% over values computed using the standard uniformly bright spherical finite disk factor. For rapidly rotating stars, limb darkening makes 'sub-stellar' gravity darkening the dominant effect in the radial and latitudinal OFD factors, and lessens the impact of gravity darkening at other visible latitudes (nearer to the oblate limb). Thus, the radial radiative driving is generally stronger over the poles and weaker over the equator, following the gravity darkening at these latitudes. The nonradial radiative driving is considerably smaller in magnitude than the radial component, but is directed both away from the equatorial plane and in a retrograde azimuthal direction, acting to decrease the effective stellar rotation velocity. These forces thus weaken the equatorward wind compression compared to wind models computed with nonrotating finite disk factors.

Substellar Companions to weak-line TTauri Stars

NASA Astrophysics Data System (ADS)

Brandner, W.; Alcala, J. M.; Covino, E.; Frink, S.

1997-05-01

Weak-line TTauri stars, contrary to classical TTauri stars, no longer possess massive circumstellar disks. In weak-line TTauri stars, the circumstellar matter was either accreted onto the TTauri star or has been redistributed. Disk instabilities in the outer disk might result in the formation of brown dwarfs and giant planets. Based on photometric and spectroscopic studies of ROSAT sources, we have selected an initial sample of 200 weak-line TTauri stars in the Chamaeleon T association and the Scorpius Centaurus OB association. In the course of follow-up observations we identified visual and spectroscopic binary stars and excluded them from our final list, as the complex dynamics and gravitational interaction in binary systems might aggravate or even completely inhibit the formation of planets (depending on physical separation of the binary components and their mass-ratio). The membership of individual stars to the associations was established from proper motion studies and radial velocity surveys. Our final sample consists of 70 single weak-line TTauri stars. We have initiated a program to spatially RESOLVE young brown dwarfs and young giant planets as companions to single weak-line TTauri stars using adaptive optics at the ESO 3.6m telescope and HST/NICMOS. In this poster we describe the observing strategy and present first results of our adaptive optics observations.

The chemically peculiar double-lined spectroscopic binary HD 90264

NASA Astrophysics Data System (ADS)

Quiroga, C.; Torres, A. F.; Cidale, L. S.

2010-10-01

Context. HD 90264 is a chemically peculiar (CP) double-lined spectroscopic binary system of the type He-weak. Double-lined binaries are unique sources of data for stellar masses, physical properties, and evolutionary aspects of stars. Therefore, the determination of orbital elements is of great importance to study how the physical characteristics of CP stars are affected by a companion. Aims: We carried out a detailed spectral and polarimetric study of the spectroscopic binary system HD 90264 to characterize its orbit, determine the stellar masses, and investigate the spectral variability and possible polarization of the binary components. Methods: We employed medium-resolution échelle spectra and polarimetric data obtained at the 2.15-m telescope at CASLEO Observatory, Argentina. We measured radial velocities and line equivalent widths with IRAF packages. The radial velocity curves of both binary components were obtained combining radial velocity data derived from the single line of Hg II λ3984 Åand the double lines of Mg II λ4481 Å. Polarimetric data were studied by means of the statistical method of Clarke & Stewart and the Welch test. Results: We found that both components of the binary system are chemically peculiar stars, deficient in helium, where the primary is a He variable and the secondary is a Hg-Mn star. We derived for the first time the orbital parameters of the binary system. We found that the system has a quasi-circular orbit (e ~ 0.04) with an orbital period of 15.727 days. Taking into account the circular orbit solution, we derived a mass ratio of q = MHe-w/MHg-Mn = 1.22. We also found a rotational period of around 15-16 days, suggesting a spin-orbit synchronization. Possible signs of intrinsic polarization have also been detected. Conclusions: HD 90264 is the first known binary system comprised of a He variable star as the primary component and a Hg-Mn star as the secondary one. Based on observations taken at Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación and the National Universities of La Plata, Córdoba and San Juan.

New features in the structure of the classical Kuiper Belt

NASA Astrophysics Data System (ADS)

Gladman, Brett; Bannister, Michele T.; Alexandersen, Mike; Chen, Ying-Tung; Gwyn, Stephen; Kavelaars, J. J.; Petit, Jean-Marc; Volk, Kathryn; OSSOS Collaboration

2016-10-01

We report fascinating new dynamical structures emerging from a higher precision view of the classical Kuiper belt (the plentiful non-resonant orbits with semimajor axes in roughly the a=35-60 au range). The classical Kuiper Belt divides into multiple sub-populations: an 'inner' classical belt (a small group of non-resonant objects with a<39.4 au where the 3:2 resonance is located), an abundant 'main' classical belt (between the 3:2 and the 2:1 at a=47.4 au), and a difficult to study outer classical belt beyond the 2:1. We examine the dynamical structure, as precisely revealed in the detections from OSSOS (the Outer Solar System Origin's Survey); the data set is of superb quality in terms of orbital element and numbers of detections (Kavelaars et al, this meeting).The previous CFEPS survey showed that the main classical belt requires a complex dynamical substructure that goes beyond a simple 'hot versus cold' division based primarily on orbital inclination; the 'cold' inclination component requires two sub-components in the semimajor axis and perihelion distance q space (Petit et al 2011). CFEPS modelled this as a 'stirred' component present at all a=40-47 AU semimajor axes, with a dense superposed 'kernel' near a=44 AU at low eccentricity; the first OSSOS data release remained consistent with this (Bannister et al 2016). As with the main asteroid belt, as statistics and orbital quality improve we see additional significant substructure emerging in the classical belt's orbital distribution.OSSOS continues to add evidence that the cold stirred component extends smoothly beyond the 2:1 (Bannister et al 2016). Unexpectedly, the data also reveal the clear existence of a paucity of orbits just beyond the outer edge of the kernel; there are significantly fewer TNOs in the narrow semimajor axis band from a=44.5-45.0 AU. This may be related to the kernel population's creation, or it may be an independent feature created by planet migration as resonances moved in the primordial Kuiper Belt.

Aerobraking orbital transfer vehicle

NASA Technical Reports Server (NTRS)

Scott, Carl D. (Inventor); Nagy, Kornel (Inventor); Roberts, Barney B. (Inventor); Ried, Robert C. (Inventor); Kroll, Kenneth R. (Inventor); Gamble, Joe (Inventor)

1989-01-01

An aerobraking orbital transfer vehicle which includes an aerobraking device which also serves as a heat shield in the shape of a raked-off elliptic or circular cone with a circular or elliptical base, and with an ellipsoid or other blunt shape nose. The aerobraking device is fitted with a toroid-like skirt and is integral with the support structure of the propulsion system and other systems of the space vehicle. The vehicle is intended to be transported in components to a space station in lower earth orbit where it is assembled for use as a transportation system from low earth orbit to geosynchronous earth orbit and return. Conventional guidance means are included for autonomous flight.

Hf thickness dependence of spin-orbit torques in Hf/CoFeB/MgO heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramaswamy, Rajagopalan; Qiu, Xuepeng; Dutta, Tanmay

We have studied the spin-orbit torques in perpendicularly magnetized Hf/CoFeB/MgO system, by systematically varying the thickness of Hf underlayer. We have observed a sign change of effective fields between Hf thicknesses of 1.75 and 2 nm, indicating that competing mechanisms, such as the Rashba and spin Hall effects, contribute to spin-orbit torques in our system. For larger Hf thicknesses (>2 nm), both the components of spin-orbit torques arise predominantly from the bulk spin Hall effect. We have also confirmed these results using spin-orbit torque induced magnetization switching measurements. Our results could be helpful in designing Hf based SOT devices.

1SWASP J200503.05-343726.5: A high mass ratio eclipsing binary near the period limit

NASA Astrophysics Data System (ADS)

Bin, Zhang; Shengbang, Qian; Zejda, Miloslav; Liying, Zhu; Nianping, Liu

2017-07-01

First CCD photometric light curves of the eclipsing binary system 1SWASP J200503.05-343726.5 are presented. Our complete light curves in V, R and I bands using the Bessell filter show an out-of-eclipsing distortion, which means that the components of the system may be active. The preliminary photometric solutions with a cool star-spot are derived by using the 2013 version of the Wilson-Devinney (W-D) code. The photometric solutions suggest that 1SWASP J200503.05-343726.5 is a shallow-contact eclipsing binary(f = 9.0 %) with a mass ratio of q = 1.0705 , which is very high for late-type binary systems near the period limit. The primary component is about 230 K hotter than the secondary component. Based on our new CCD eclipse times, the orbital period change was analyzed. According to O - C diagram, the orbital period of the 1SWASP J200503.05-343726.5 shows an increase at a rate of P˙ = + 5.43 ×10-8 days year-1. The period increase may be caused by mass transfer from the less massive component to the more massive one. This shallow-contact system may be formed from a detached short-period binary via orbital shrinkage because of dynamical interactions with a third component or by magnetic braking.

The Visual Orbit and Evolutionary State of 12 Bootes

NASA Technical Reports Server (NTRS)

Boden, A.; Creech-Eakman, M.; Queloz, D.

1999-01-01

Herein we report the determination of the 12 Boo visual orbit from near-infrared, long-baseline interferometric measurements taken with the Palomar Testbed Interferometer (PTI). We further add photometric and spectroscopic measurements in an attempt to understand the fundamental stellar parameters and evolution of the 12 Boo components.

Compendium of Single Event Effects Test Results for Commercial Off-The-Shelf and Standard Electronics for Low Earth Orbit and Deep Space Applications

NASA Technical Reports Server (NTRS)

Reddell, Brandon D.; Bailey, Charles R.; Nguyen, Kyson V.; O'Neill, Patrick M.; Wheeler, Scott; Gaza, Razvan; Cooper, Jaime; Kalb, Theodore; Patel, Chirag; Beach, Elden R.;

Compendium of Single Event Effects (SEE) Test Results for COTS and Standard Electronics for Low Earth Orbit and Deep Space Applications

NASA Technical Reports Server (NTRS)

Reddell, Brandon; Bailey, Chuck; Nguyen, Kyson; O'Neill, Patrick; Gaza, Razvan; Patel, Chirag; Cooper, Jaime; Kalb, Theodore

2017-01-01

We present the results of SEE testing with high energy protons and with low and high energy heavy ions. This paper summarizes test results for components considered for Low Earth Orbit and Deep Space applications.

Separation of spin and orbital angular coherence momenta in the second-order coherence theory of vector electromagnetic fields.

PubMed

Wang, Wei; Takeda, Mitsuo

2007-09-15

In analogy with the separation of the total optical angular momentum into a spin and an orbital part in electrodynamics, we introduce a new concept of spin and orbital angular coherence momenta into the general coherence theory of vector electromagnetic fields. The properties of the newly introduced spin and orbital angular coherence momenta are investigated through the decomposition of the total coherence angular momentum into the sum of these two components, and their separate conservations have been derived for what is believed to be the first time.

Expected orbit determination performance for the TOPEX/Poseidon mission

NASA Technical Reports Server (NTRS)

Nerem, R. S.; Putney, Barbara H.; Marshall, J. A.; Lerch, Francis J.; Pavlis, Erricos C.; Klosko, Steven M.; Luthcke, Scott B.; Patel, Girish B.; Williamson, Ronald G.; Zelensky, Nikita P.

1993-01-01

Each of the components required for the computation of precise orbits for the TOPEX/Poseidon (T/P) spacecraft - gravity field modeling, nonconservative force modeling, and satellite tracking technologies - is examined. The research conducted in the Space Geodesy Branch at Goddard Space Flight Center in preparation for meeting the 13-cm radial orbit accuracy requirement for the T/P mission is outlined. New developments in modeling the earth's gravitational field and modeling the complex nonconservative forces acting on T/P are highlighted. The T/P error budget is reviewed, and a prelaunch assessment of the predicted orbit determination accuracies is summarized.

Three-dimensional orbit and physical parameters of HD 6840

NASA Astrophysics Data System (ADS)

Wang, Xiao-Li; Ren, Shu-Lin; Fu, Yan-Ning

2016-02-01

HD 6840 is a double-lined visual binary with an orbital period of ˜7.5 years. By fitting the speckle interferometric measurements made by the 6 m BTA telescope and 3.5 m WIYN telescope, Balega et al. gave a preliminary astrometric orbital solution of the system in 2006. Recently, Griffin derived a precise spectroscopic orbital solution from radial velocities observed with OPH and Cambridge Coravel. However, due to the low precision of the determined orbital inclination, the derived component masses are not satisfying. By adding the newly collected astrometric data in the Fourth Catalog of Interferometric Measurements of Binary Stars, we give a three-dimensional orbit solution with high precision and derive the preliminary physical parameters of HD 6840 via a simultaneous fit including both astrometric and radial velocity measurements.

Orbital component extraction by time-variant sinusoidal modeling.

NASA Astrophysics Data System (ADS)

Sinnesael, Matthias; Zivanovic, Miroslav; De Vleeschouwer, David; Claeys, Philippe; Schoukens, Johan

2016-04-01

Accurately deciphering periodic variations in paleoclimate proxy signals is essential for cyclostratigraphy. Classical spectral analysis often relies on methods based on the (Fast) Fourier Transformation. This technique has no unique solution separating variations in amplitude and frequency. This characteristic makes it difficult to correctly interpret a proxy's power spectrum or to accurately evaluate simultaneous changes in amplitude and frequency in evolutionary analyses. Here, we circumvent this drawback by using a polynomial approach to estimate instantaneous amplitude and frequency in orbital components. This approach has been proven useful to characterize audio signals (music and speech), which are non-stationary in nature (Zivanovic and Schoukens, 2010, 2012). Paleoclimate proxy signals and audio signals have in nature similar dynamics; the only difference is the frequency relationship between the different components. A harmonic frequency relationship exists in audio signals, whereas this relation is non-harmonic in paleoclimate signals. However, the latter difference is irrelevant for the problem at hand. Using a sliding window approach, the model captures time variations of an orbital component by modulating a stationary sinusoid centered at its mean frequency, with a single polynomial. Hence, the parameters that determine the model are the mean frequency of the orbital component and the polynomial coefficients. The first parameter depends on geologic interpretation, whereas the latter are estimated by means of linear least-squares. As an output, the model provides the orbital component waveform, either in the depth or time domain. Furthermore, it allows for a unique decomposition of the signal into its instantaneous amplitude and frequency. Frequency modulation patterns can be used to reconstruct changes in accumulation rate, whereas amplitude modulation can be used to reconstruct e.g. eccentricity-modulated precession. The time-variant sinusoidal model is applied to well-established Pleistocene benthic isotope records to evaluate its performance. Zivanovic M. and Schoukens J. (2010) On The Polynomial Approximation for Time-Variant Harmonic Signal Modeling. IEEE Transactions On Audio, Speech, and Language Processing vol. 19, no. 3, pp. 458-467. Doi: 10.1109/TASL.2010.2049673. Zivanovic M. and Schoukens J. (2012) Single and Piecewise Polynomials for Modeling of Pitched Sounds. IEEE Transactions On Audio, Speech, and Language Processing vol. 20, no. 4, pp. 1270-1281. Doi: 10.1109/TASL.2011.2174228.

Single-step methods for predicting orbital motion considering its periodic components

NASA Astrophysics Data System (ADS)

Lavrov, K. N.

1989-01-01

Modern numerical methods for integration of ordinary differential equations can provide accurate and universal solutions to celestial mechanics problems. The implicit single sequence algorithms of Everhart and multiple step computational schemes using a priori information on periodic components can be combined to construct implicit single sequence algorithms which combine their advantages. The construction and analysis of the properties of such algorithms are studied, utilizing trigonometric approximation of the solutions of differential equations containing periodic components. The algorithms require 10 percent more machine memory than the Everhart algorithms, but are twice as fast, and yield short term predictions valid for five to ten orbits with good accuracy and five to six times faster than algorithms using other methods.

Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

DTIC Science & Technology

2015-10-27

CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Eric K. Sutton 5d. PROJECT NUMBER 3001 5e. TASK NUMBER PPM00018035...principal components, hybrid model, helium model, neutral composition, low-Earth orbit 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...difficult force to determine and predict, in the orbit propagation model of low earth orbiting satellites [36]. The drag acceleration vector, ~a

Effects of the Shuttle Orbiter fuselage and elevon on the molecular distribution of water vapor from the flash evaporator system

NASA Technical Reports Server (NTRS)

Richmond, R. G.; Kelso, R. M.

1980-01-01

A concern has arisen regarding the emissive distribution of water molecules from the shuttle orbiter flash evaporator system (FES). The role of the orbiter fuselage and elevon in affecting molecular scattering distributions was nuclear. The effect of these components were evaluated. Molecular distributions of the water vapor effluents from the FE were measured. These data were compared with analytically predicted values and the resulting implications were calculated.

Experimental evaluation of the Skylab orbital workshop ventilation system concept

NASA Technical Reports Server (NTRS)

Allums, S. L.; Hastings, L. J.; Ralston, J. T.

1972-01-01

Extensive testing was conducted to evaluate the Orbital Workshop ventilation concept. Component tests were utilized to determine the relationship between operating characteristics at 1 and 0.34 atm. System tests were conducted at 1 atm within the Orbital Workshop full-scale mockup to assess delivered volumetric flow rate and compartment air velocities. Component tests with the Anemostat circular diffusers (plenum- and duct-mounted) demonstrated that the diffuser produced essentially equivalent airflow patterns and velocities in 1- and 0.34-atm environments. The tests also showed that the pressure drop across the diffuser could be scaled from 1 to 0.34 atm using the atmosphere pressure ratio. Fan tests indicated that the performance of a multiple, parallel-mounted fan cluster could be predicted by summing the single-fan flow rates at a given delta P.

Astronomical component estimation (ACE v.1) by time-variant sinusoidal modeling

NASA Astrophysics Data System (ADS)

Sinnesael, Matthias; Zivanovic, Miroslav; De Vleeschouwer, David; Claeys, Philippe; Schoukens, Johan

2016-09-01

Accurately deciphering periodic variations in paleoclimate proxy signals is essential for cyclostratigraphy. Classical spectral analysis often relies on methods based on (fast) Fourier transformation. This technique has no unique solution separating variations in amplitude and frequency. This characteristic can make it difficult to correctly interpret a proxy's power spectrum or to accurately evaluate simultaneous changes in amplitude and frequency in evolutionary analyses. This drawback is circumvented by using a polynomial approach to estimate instantaneous amplitude and frequency in orbital components. This approach was proven useful to characterize audio signals (music and speech), which are non-stationary in nature. Paleoclimate proxy signals and audio signals share similar dynamics; the only difference is the frequency relationship between the different components. A harmonic-frequency relationship exists in audio signals, whereas this relation is non-harmonic in paleoclimate signals. However, this difference is irrelevant for the problem of separating simultaneous changes in amplitude and frequency. Using an approach with overlapping analysis frames, the model (Astronomical Component Estimation, version 1: ACE v.1) captures time variations of an orbital component by modulating a stationary sinusoid centered at its mean frequency, with a single polynomial. Hence, the parameters that determine the model are the mean frequency of the orbital component and the polynomial coefficients. The first parameter depends on geologic interpretations, whereas the latter are estimated by means of linear least-squares. As output, the model provides the orbital component waveform, either in the depth or time domain. Uncertainty analyses of the model estimates are performed using Monte Carlo simulations. Furthermore, it allows for a unique decomposition of the signal into its instantaneous amplitude and frequency. Frequency modulation patterns reconstruct changes in accumulation rate, whereas amplitude modulation identifies eccentricity-modulated precession. The functioning of the time-variant sinusoidal model is illustrated and validated using a synthetic insolation signal. The new modeling approach is tested on two case studies: (1) a Pliocene-Pleistocene benthic δ18O record from Ocean Drilling Program (ODP) Site 846 and (2) a Danian magnetic susceptibility record from the Contessa Highway section, Gubbio, Italy.

A spectroscopic search for colliding stellar winds in O-type close binary systems. III - 29 UW Canis Majoris

NASA Technical Reports Server (NTRS)

Wiggs, Michael S.; Gies, Douglas R.

1993-01-01

The orbital-phase variations in the optical emission lines and UV P Cygni lines of the massive O-type binary 29 UW Canis Majoris are investigated in a search for evidence of colliding winds. High SNR spectra of the H-alpha and He I 6678-A emission lines are presented, and radial velocity curves for several features associated with the photosphere of the more luminous primary star are given. The H-alpha features consists of a P Cygni component that shares the motion of the primary, and which probably originates at the base of its wind, and a broad, stationary emission component. It is proposed that the broad emission forms in a plane midway between the stars where the winds collide. A simple geometric model is used to show that this placement of the broad component can explain the lack of orbital velocity shifts, the near-constancy of the emission strength throughout the orbit, the large velocities associated with the H-alpha wings, and the constancy of the velocity range observed.

Storm Time Evolution of Outer Radiation Belt Relativistic Electrons by a Nearly Continuous Distribution of Chorus

NASA Astrophysics Data System (ADS)

Yang, Chang; Xiao, Fuliang; He, Yihua; Liu, Si; Zhou, Qinghua; Guo, Mingyue; Zhao, Wanli

2018-03-01

During the 13-14 November 2012 storm, Van Allen Probe A simultaneously observed a 10 h period of enhanced chorus (including quasi-parallel and oblique propagation components) and relativistic electron fluxes over a broad range of L = 3-6 and magnetic local time = 2-10 within a complete orbit cycle. By adopting a Gaussian fit to the observed wave spectra, we obtain the wave parameters and calculate the bounce-averaged diffusion coefficients. We solve the Fokker-Planck diffusion equation to simulate flux evolutions of relativistic (1.8-4.2 MeV) electrons during two intervals when Probe A passed the location L = 4.3 along its orbit. The simulating results show that chorus with combined quasi-parallel and oblique components can produce a more pronounced flux enhancement in the pitch angle range ˜45°-80°, consistent well with the observation. The current results provide the first evidence on how relativistic electron fluxes vary under the drive of almost continuously distributed chorus with both quasi-parallel and oblique components within a complete orbit of Van Allen Probe.

The formation of Kuiper-belt binaries through exchange reactions.

PubMed

Funato, Yoko; Makino, Junichiro; Hut, Piet; Kokubo, Eiichiro; Kinoshita, Daisuke

2004-02-05

Recent observations have revealed that an unexpectedly high fraction--a few per cent--of the trans-Neptunian objects (TNOs) that inhabit the Kuiper belt are binaries. The components have roughly equal masses, with very eccentric orbits that are wider than a hundred times the radius of the primary. Standard theories of binary asteroid formation tend to produce close binaries with circular orbits, so two models have been proposed to explain the unique characteristics of the TNOs. Both models, however, require extreme assumptions regarding the size distribution of the TNOs. Here we report a mechanism that is capable of producing binary TNOs with the observed properties during the early stages of their formation and growth. The only required assumption is that the TNOs were initially formed through gravitational instabilities in the protoplanetary dust disk. The basis of the mechanism is an exchange reaction in which a binary whose primary component is much more massive than the secondary interacts with a third body, whose mass is comparable to that of the primary. The low-mass secondary component is ejected and replaced by the third body in a wide but eccentric orbit.

Multi-GNSS orbit determination using satellite laser ranging

NASA Astrophysics Data System (ADS)

Bury, Grzegorz; Sośnica, Krzysztof; Zajdel, Radosław

2018-04-01

Galileo, BeiDou, QZSS, and NavIC are emerging global navigation satellite systems (GNSSs) and regional navigation satellite systems all of which are equipped with laser retroreflector arrays for range measurements. This paper summarizes the GNSS-intensive tracking campaigns conducted by the International Laser Ranging Service and provides results from multi-GNSS orbit determination using solely SLR observations. We consider the whole constellation of GLONASS, all active Galileo, four BeiDou satellites: 1 MEO, 3 IGSO, and one QZSS. We analyze the influence of the number of SLR observations on the quality of the 3-day multi-GNSS orbit solution. About 60 SLR observations are needed for obtaining MEO orbits of sufficient quality with the root mean square (RMS) of 3 cm for the radial component when compared to microwave-based orbits. From the analysis of a minimum number of tracking stations, when considering the 3-day arcs, 5 SLR stations do not provide a sufficient geometry of observations. The solution obtained using ten stations is characterized with RMS of 4, 9, and 18 cm in the radial, along-track, and cross-track direction, respectively, for MEO satellites. We also investigate the impact of the length of orbital arc on the quality of SLR-derived orbits. Hence, 5- and 7-day arcs constitute the best solution, whereas 3-day arcs are of inferior quality due to an insufficient number of SLR observations and 9-day arcs deteriorate the along-track component. The median RMS from the comparison between 7-day orbital arcs determined using SLR data with microwave-based orbits assumes values in the range of 3-4, 11-16, and 15-27 cm in radial, along-track, and cross-track, respectively, for MEO satellites. BeiDou IGSO and QZSS are characterized by RMS values higher by a factor of 8 and 24, respectively, than MEO orbits.

Mars approach navigation using Doppler and range measurements to surface beacons and orbiting spacecraft

NASA Technical Reports Server (NTRS)

Thurman, Sam W.; Estefan, Jeffrey A.

1991-01-01

Approximate analytical models are developed and used to construct an error covariance analysis for investigating the range of orbit determination accuracies which might be achieved for typical Mars approach trajectories. The sensitivity or orbit determination accuracy to beacon/orbiter position errors and to small spacecraft force modeling errors is also investigated. The results indicate that the orbit determination performance obtained from both Doppler and range data is a strong function of the inclination of the approach trajectory to the Martian equator, for surface beacons, and for orbiters, the inclination relative to the orbital plane. Large variations in performance were also observed for different approach velocity magnitudes; Doppler data in particular were found to perform poorly in determining the downtrack (along the direction of flight) component of spacecraft position. In addition, it was found that small spacecraft acceleration modeling errors can induce large errors in the Doppler-derived downtrack position estimate.

The Moving Group Targets of the Seeds High-Contrast Imaging Survey of Exoplanets and Disks: Results and Observations from the First Three Years

NASA Technical Reports Server (NTRS)

Brandt, Timothy D.; Kuzuhara, Masayuki; McElwain, Michael W.; Schlieder, Joshua E.; Wisniewski, John P.; Turner, Edwin L.; Carson, J.; Matsuo, T.; Biller, B.; Bonnefoy, M.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osorio, Mayra; Anglada, Guillem; Macías, Enrique

We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ∼25-30 AU, whose inner region is devoid of detectable 7 mm emission. We interpret this ring as tracing the rim of an inner cavity or gap, possibly created by a planet or a substellar companion. The ring appears asymmetric, with the western part significantly brighter than the eastern one. This azimuthal asymmetry is reminiscent of the lopsided structures that are expected to be produced as a consequence of trappingmore » of large dust grains. Our observations also reveal an outer annular gap at radii from ∼40 to ∼70 AU. Unlike other sources, the radii of the inner cavity, the ring, and the outer gap observed in the 7 mm images, which trace preferentially the distribution of large (millimeter/centimeter sized) dust grains, coincide with those obtained from a previous near-infrared polarimetric image, which traces scattered light from small (micron-sized) dust grains. We model the broadband spectral energy distribution and the 7 mm images to constrain the disk physical structure. From this modeling we infer the presence of a small (radius ∼0.6 AU) residual disk inside the central cavity, indicating that the HD 169142 disk is a pre-transitional disk. The distribution of dust in three annuli with gaps in between them suggests that the disk in HD 169142 is being disrupted by at least two planets or substellar objects.« less

Lithium in Open Cluster Red Giants Hosting Substellar Companions

NASA Technical Reports Server (NTRS)

Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Carpenter, Kenneth G.

2016-01-01

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and (12)C/13C in a small sample of red giants (RGs) in three open clusters that are each home to a RG star that hosts a substellar companion (SSC) (NGC 2423 3, NGC 4349 127, and BD+12 1917 in M67). Our goal is to explore whether the presence of SSCs influences the Li content. Both (12)C/13C and stellar rotation are measured as additional tracers of stellar mixing. One of the companion hosts, NGC 2423?3, is found to be Li-rich with A(Li)(sub NLTE) = 1.56 dex, and this abundance is significantly higher than the A(Li) of the two comparison stars in NGC 2423. All three SSC hosts have the highest A(Li) and (12)C/13C when compared to the control RGs in their respective clusters; however, except for NGC 2423?3, at least one control star has similarly high abundances within the uncertainties. Higher A(Li) could suggest that the formation or presence of planets plays a role in the degree of internal mixing on or before the RG branch. However, a multitude of factors affect A(Li) during the RG phase, and when the abundances of our sample are compared with the abundances of RGs in other open clusters available in the literature, we find that they all fall well within a much larger distribution of A(Li) and (12)C/13C. Thus, even the high Li in NGC 2423 3 cannot be concretely tied to the presence of the SSC.

Radio emission in ultracool dwarfs: The nearby substellar triple system VHS 1256-1257

NASA Astrophysics Data System (ADS)

Guirado, J. C.; Azulay, R.; Gauza, B.; Pérez-Torres, M. A.; Rebolo, R.; Climent, J. B.; Zapatero Osorio, M. R.

2018-02-01

Aim. With the purpose of investigating the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92-125723.9 (hereafter VHS 1256-1257); this system is composed by an equal-mass M7.5 binary and a L7 low-mass substellar object located at only 15.8 pc. Methods: We observed in phase-reference mode the system VHS 1256-1257 with the Karl G. Jansky Very Large Array at X band and L band and with the European VLBI Network at L band in several epochs during 2015 and 2016. Results: We discovered radio emission at X band spatially coincident with the equal-mass M7.5 binary with a flux density of 60 μJy. We determined a spectral index α = ‑1.1 ± 0.3 between 8 and 12 GHz, suggesting that non-thermal, optically thin, synchrotron, or gyrosynchrotron radiation is responsible for the observed radio emission. Interestingly, no signal is seen at L band where we set a 3σ upper limit of 20 μJy. This might be explained by strong variability of the binary or self-absorption at this frequency. By adopting the latter scenario and gyrosynchrotron radiation, we constrain the turnover frequency to be in the interval 5-8.5 GHz, from which we infer the presence of kG-intense magnetic fields in the M7.5 binary. Our data impose a 3σ upper bound to the radio flux density of the L7 object of 9 μJy at 10 GHz.

The Widest-separation Substellar Companion Candidate to a Binary T Tauri Star

NASA Astrophysics Data System (ADS)

Kuzuhara, M.; Tamura, M.; Ishii, M.; Kudo, T.; Nishiyama, S.; Kandori, R.

2011-04-01

The results of near-infrared imaging and spectroscopy of a substellar companion (SR12 C), with a possible planetary mass, of a binary T Tauri star (SR12 AB) in the ρ Ophiuchi star-forming region are presented. The object is separated by ~8farcs7, corresponding to ~1100 AU at 125 pc, and has an H-band brightness of 15.2 mag and infrared spectra suggesting a spectral type of M9.0 ± 0.5. It is confirmed that SR12 C is physically related to the ρ Ophiuchi star-forming region from its common proper motion with SR12 AB and its youth is confirmed by a gravity-sensitive spectral feature. Furthermore, based on the number of known members of the ρ Ophiuchi star-forming region in the area in which SR12 AB exists, the probability of a chance alignment is ~1% and it is therefore likely that SR12 C is physically associated with SR12 AB. The mass of SR12 C is estimated by comparing its estimated luminosity and assumed age with the theoretical age-luminosity relation. SR12 C is identified as an extremely low-mass (0.013 ± 0.007 M sun) object, but its separation from its parent star is the widest among planetary-mass companion (PMC) candidates imaged to date. In addition, SR12 C is the first PMC candidate directly imaged around a binary star. This discovery suggests that PMCs form via multiple star formation processes including disk gravitational instability and cloud core fragmentation.

Lithium in Open Cluster Red Giants Hosting Substellar Companions

NASA Astrophysics Data System (ADS)

Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Carpenter, Kenneth G.

2016-02-01

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and 12C/13C in a small sample of red giants (RGs) in three open clusters that are each home to a RG star that hosts a substellar companion (SSC) (NGC 2423 3, NGC 4349 127, and BD+12 1917 in M67). Our goal is to explore whether the presence of SSCs influences the Li content. Both 12C/13C and stellar rotation are measured as additional tracers of stellar mixing. One of the companion hosts, NGC 2423 3, is found to be Li-rich with A(Li){}{{NLTE}} = 1.56 dex, and this abundance is significantly higher than the A(Li) of the two comparison stars in NGC 2423. All three SSC hosts have the highest A(Li) and 12C/13C when compared to the control RGs in their respective clusters; however, except for NGC 2423 3, at least one control star has similarly high abundances within the uncertainties. Higher A(Li) could suggest that the formation or presence of planets plays a role in the degree of internal mixing on or before the RG branch. However, a multitude of factors affect A(Li) during the RG phase, and when the abundances of our sample are compared with the abundances of RGs in other open clusters available in the literature, we find that they all fall well within a much larger distribution of A(Li) and 12C/13C. Thus, even the high Li in NGC 2423 3 cannot be concretely tied to the presence of the SSC.

The moving group targets of the seeds high-contrast imaging survey of exoplanets and disks: Results and observations from the first three years

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, Timothy D.; Turner, Edwin L.; Janson, M.

2014-05-01

We present results from the first three years of observations of moving group (MG) targets in the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) high-contrast imaging survey of exoplanets and disks using the Subaru telescope. We achieve typical contrasts of ∼10{sup 5} at 1'' and ∼10{sup 6} beyond 2'' around 63 proposed members of nearby kinematic MGs. We review each of the kinematic associations to which our targets belong, concluding that five, β Pictoris (∼20 Myr), AB Doradus (∼100 Myr), Columba (∼30 Myr), Tucana-Horogium (∼30 Myr), and TW Hydrae (∼10 Myr), are sufficiently well-defined to constrain the agesmore » of individual targets. Somewhat less than half of our targets are high-probability members of one of these MGs. For all of our targets, we combine proposed MG membership with other age indicators where available, including Ca II HK emission, X-ray activity, and rotation period, to produce a posterior probability distribution of age. SEEDS observations discovered a substellar companion to one of our targets, κ And, a late B star. We do not detect any other substellar companions, but do find seven new close binary systems, of which one still needs to be confirmed. A detailed analysis of the statistics of this sample, and of the companion mass constraints given our age probability distributions and exoplanet cooling models, will be presented in a forthcoming paper.« less

Analysis of the possible cause of break up of PSLV-C3/PS4 stage

NASA Astrophysics Data System (ADS)

Bandyopadhyay, P.; Sharma, R.; Adimurthy, V.

On 19t h December 2001 the orbiting spent PS4 stage of PSLV -C3 had undergone a break up. Following this event, the Two Line Element (TLE) sets of more than 300 debris pieces from the upper stage are available in public domain by January 2002. These TLE sets are the major input used in this study. Here the velocity components imparted on the fragments are evaluated by a new approach, which is less sensitive to the errors in the TLE sets. In Ref-1, the normal, radial and tangential components of fragment velocity additions are estimated from the differences in semi-major axis, eccentricity and inclination with respect to those of parent object. Unfortunately, when the parent orbit has small eccentricity or the break up occurs near either apogee or perigee, as it is likely in the case of PSLV-C3/PS4, the computation of radial component of velocity increment becomes close to a singular point and hence prone to errors because of imperfect orbital element data. In Ref-2, velocity increments are estimated from semi-major axis, eccentricity, inclination, and right ascension of ascending node and true anomaly of fragments as well as parent at the time of break up. It is very difficult to obtain true anomaly of fragments at the time of break up by propagating the element sets of debris pieces backward in time owing to uncertainties in orbital elements and drag parameters. Moreover, whenever the apogee of fragment orbit, computed from the TLE sets, becomes less than the perigee of parent orbit, this method does not yield any solution for radial component of velocity increment. The authors have estimated three components of velocity addition, utilizing relations involving the differences in semi-major axis, eccentricity and inclination and argument of perigee (Ref- 3) in a particular combination and sequence, which avoids the singularity in the computation. With this approach, the characteristics of velocity additions are similar in all the three directions and velocity addition histograms in these three directions are almost symmetric about zero. These results are pointer to the possibility of fragmentation from explosion in PSLV-C3/PS4 stage. It is also estimated that about 75 % of the total number of debris pieces from this break up would decay by the end 2002. References: (1) Nicholas L. Johnson &Darren S. McKnight, Artificial Space Debris, Orbit Foundation, 1987. (2) James G Miller, Velocity Distribution of Satellite Breakups, AAS 99-445, 1999. (3) Meirovitch L., Methods of Analytical Dynamics , McGraw Hill Company, 1970.

Deadly Sunflower Orbits

NASA Astrophysics Data System (ADS)

Hamilton, Douglas P.

2018-04-01

Solar radiation pressure is usually very effective at removing hazardous millimeter-sized debris from distant orbits around asteroidsand other small solar system bodies (Hamilton and Burns 1992). Theprimary loss mechanism, driven by the azimuthal component of radiationpressure, is eccentricity growth followed by a forced collision withthe central body. One large class of orbits, however, neatly sidestepsthis fate. Orbits oriented nearly perpendicular to the solar directioncan maintain their face-on geometry, oscillating slowly around a stableequilibrium orbit. These orbits, designated sunflower orbits, arerelated to terminator orbits studied by spacecraft mission designers(Broschart etal. 2014).Destabilization of sunflower orbits occurs only for particles smallenough that radiation pressure is some tens of percent the strength ofthe central body's direct gravity. This greatly enhanced stability,which follows from the inability of radiation incident normal to theorbit to efficiently drive eccentricities, presents a threat tospacecraft missions, as numerous dangerous projectiles are potentiallyretained in orbit. We have investigated sunflower orbits insupport of the New Horizons, Aida, and Lucy missions and find thatthese orbits are stable for hazardous particle sizes at asteroids,comets, and Kuiper belt objects of differing dimensions. Weinvestigate the sources and sinks for debris that might populate suchorbits, estimate timescales and equilibrium populations, and willreport on our findings.

Orbit Alignment in Triple Stars

NASA Astrophysics Data System (ADS)

Tokovinin, Andrei

2017-08-01

The statistics of the angle Φ between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. A correlation between apparent revolution directions proves the partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ˜50 au, where the average Φ is about 20^\\circ . In contrast, outer orbits wider than 1000 au are not aligned with the inner orbits. It is established that the orbit alignment decreases with the increasing mass of the primary component. The average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. The analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of Φ is likely bimodal, where 80% of triples have {{Φ }}< 70^\\circ and the remaining ones are randomly aligned.

Carbon-carbon primary structure for SSTO vehicles

NASA Astrophysics Data System (ADS)

Croop, Harold C.; Lowndes, Holland B.

1997-01-01

A hot structures development program is nearing completion to validate use of carbon-carbon composite structure for primary load carrying members in a single-stage-to-orbit, or SSTO, vehicle. A four phase program was pursued which involved design development and fabrication of a full-scale wing torque box demonstration component. The design development included vehicle and component selection, design criteria and approach, design data development, demonstration component design and analysis, test fixture design and analysis, demonstration component test planning, and high temperature test instrumentation development. The fabrication effort encompassed fabrication of structural elements for mechanical property verification as well as fabrication of the demonstration component itself and associated test fixturing. The demonstration component features 3D woven graphite preforms, integral spars, oxidation inhibited matrix, chemical vapor deposited (CVD) SiC oxidation protection coating, and ceramic matrix composite fasteners. The demonstration component has been delivered to the United States Air Force (USAF) for testing in the Wright Laboratory Structural Test Facility, WPAFB, OH. Multiple thermal-mechanical load cycles will be applied simulating two atmospheric cruise missions and one orbital mission. This paper discusses the overall approach to validation testing of the wing box component and presents some preliminary analytical test predictions.

A new empirical solar radiation pressure model for BeiDou GEO satellites

NASA Astrophysics Data System (ADS)

Liu, Junhong; Gu, Defeng; Ju, Bing; Shen, Zhen; Lai, Yuwang; Yi, Dongyun

2016-01-01

Two classic empirical solar radiation pressure (SRP) models, the Extended Center for Orbit Determination in Europe (CODE) Orbit Model ECOM 5 and ECOM 9 have been widely used for Global Positioning System (GPS) Medium Earth Orbit (MEO) satellites precise orbit determination (POD). However, these two models are not suitable for BeiDou Geostationary Earth Orbit (GEO) satellites due to their special attitude control mode. With the experimental design method this paper proposes a new empirical SRP model for BeiDou GEO satellites, which is featured by three constant terms in DYX directions, two sine terms in DX directions and one cosine term in the Y direction. It is the first time to reveal that the periodic terms in the D direction are more important than those in YX directions for BeiDou GEO satellites. Compared with ECOM 5 and ECOM 9, the BeiDou GEO satellite orbits are significantly stabilized with the new SRP force model. The average orbit overlapping root mean square (RMS) achieved by the proposed model is 7.5 cm in the radial component, which is evidently improved over those of 37.4 and 13.2 cm for ECOM 5 and ECOM 9, respectively. In addition, the correlation coefficients between GEO orbit overlaps precision and the elevation angle of the Sun have been decreased to -0.12, 0.21, and -0.03 in radial, along-track and cross-track components by using the proposed model, while they are -0.94, -0.79 and -0.29 for ECOM 5 and -0.70, 0.21 and 0.10 for ECOM 9. Moreover, the standard deviation (STD) of Satellite Laser Ranging (SLR) data residuals for the GEO satellite C01 is reduced by 37.4% and 16.1% compared with those of ECOM 5 and ECOM 9 SRP models.

Orbital period studies of the two contact binaries TZ Bootis and Y Sextantis

NASA Astrophysics Data System (ADS)

Qian, S.; Liu, Q.

2000-03-01

The physical properties of the two A-type contact binaries TZ Boo and Y Sex are nearly the same. In the present paper, many of their published times of light minima are collected and the changes in their orbital periods are analyzed. It is indicated that the orbital period of TZ Boo shows several alternating jumps while it undergoes a secular decrease of -11.8x10-8 days/year. Several random jumps superposed on a secular decrease (-5.5x10-8 days/year) are also found in the period of Y Sex. The secular decrease is usually interpreted as mass transfer from the more to the less massive components, or mass and angular momentum loss (AML) from the systems. According to the AML theory, on the contact stage, the orbital AML is mainly caused by the mass transfer from the less to the more massive component and the mass ratio decreasing and orbital period gradually increasing are the corresponding results. The extremely low mass ratio and orbital angular momentum of the two systems show that they are evolved via AML and the present secular decrease in the periods may suggest that the magnetic activity in the two systems are very strong. The relation between the changes of the orbital periods and the magnetic activity in the two systems are discussed. We think that the interplay between the variable AML and variable magnetic coupling can explain both the jumps and secular decrease in the orbital periods of the two systems. Table~2 and Table~4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strabg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Electrostatic twisted modes in multi-component dusty plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayub, M. K.; National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000; Pohang University of Sciences and Technology, Pohang, Gyeongbuk 790-784

Various electrostatic twisted modes are re-investigated with finite orbital angular momentum in an unmagnetized collisionless multi-component dusty plasma, consisting of positive/negative charged dust particles, ions, and electrons. For this purpose, hydrodynamical equations are employed to obtain paraxial equations in terms of density perturbations, while assuming the Gaussian and Laguerre-Gaussian (LG) beam solutions. Specifically, approximated solutions for potential problem are studied by using the paraxial approximation and expressed the electric field components in terms of LG functions. The energy fluxes associated with these modes are computed and corresponding expressions for orbital angular momenta are derived. Numerical analyses reveal that radial/angular modemore » numbers as well as dust number density and dust charging states strongly modify the LG potential profiles attributed to different electrostatic modes. Our results are important for understanding particle transport and energy transfer due to wave excitations in multi-component dusty plasmas.« less

Photonics on the Mission to Mars

NASA Technical Reports Server (NTRS)

Watson, Michael D.

2013-01-01

Human missions to Mars present some unique challenges for photonics devices. These devices will have exposure to many different space environments. During assembly they will be exposed to the Earth orbiting environment. Upon departure they will need to function through the Earth's Van Allen Radiation Belt. While the general interplanetary environment is less challenging than the radiation belt, they will operate in this environment for 18 months, subject to sudden saturation from solar flares. These components must continue to function properly through these saturation events presenting quite a challenge to photonic components, both optical and electronic. At Mars, the orbital environment is more benign than the Earth's. Components used as part of the landing vehicles must also deal with the pervasive dust environment for 3 - 6 months. These assembly and mission execution environments provide every form of space environmental challenges to photonic components. This paper will briefly discuss each environment and the expectations on the components for successful operation over the life of the mission.

Limiting Future Collision Risk to Spacecraft: An Assessment of NASA's Meteoroid and Orbital Debris Programs

NASA Technical Reports Server (NTRS)

2011-01-01

Over the past 50 years, various NASA communities have contributed significantly to maturing NASA s meteoroid and orbital debris (MMOD)1 programs to their current state. As a result of these community efforts, and to NASA s credit, NASA s MMOD programs and models are now widely used and respected by the providers and users of both government and commercial satellites, nationally as well as internationally. Satellites have been redesigned to protect critical components from MMOD damage by moving critical components from exterior surfaces to deep inside a satellite s structure. Orbits are monitored and altered to minimize the risk of collision with tracked orbital debris. MMOD shielding added to the International Space Station (ISS) protects critical components and astronauts from potentially catastrophic damage that might result from smaller, untracked debris and meteoroid impacts. The space shuttle, as it orbited Earth, and whether docked to the ISS or not, was optimally oriented to protect its fragile thermal protection and thermal radiation systems from MMOD damage. In addition, astronauts inspected its thermal protection system for MMOD damage before the shuttle reentered Earth s atmosphere; Orion, NASA s capsule to carry astronauts to low Earth orbit, includes designs to mitigate the threat of MMOD damage and provide increased safety to the crew. When a handful of reasonable assumptions are used in NASA s MMOD models, scenarios are uncovered that conclude that the current orbital debris environment has already reached a "tipping point." That is, the amount of debris - in terms of the population of large debris objects, as well as overall mass of debris in orbit - currently in orbit has reached a threshold where it will continually collide with itself, further increasing the population of orbital debris. This increase will lead to corresponding increases in spacecraft failures, which will only create more feedback into the system, increasing the debris population growth rate. The increase thus far has been most rapid in low Earth orbit (LEO), with geosynchronous Earth orbits (GEOs) potentially suffering the same fate, but over a much longer time period. The exact timing and pace of this exponential growth are uncertain, but the serious implications of such a scenario require careful attention because of the strategic importance of U.S. space operations. The Office of Science and Technology Policy and the Office of Management and Budget contracted with the National Research Council for a study to perform three tasks: review NASA s MMOD programs and efforts, recommend in which of those NASA should increase or decrease its effort or change focus, and determine whether NASA should pursue work in any new MMOD areas. The official letter requesting the study and the full statement of task for the Committee for the Assessment of NASA s Orbital Debris Programs are in Appendixes A and B, respectively.

Electric Propulsion Technology Development for the Jupiter Icy Moons Orbiter Project

NASA Technical Reports Server (NTRS)

2004-01-01

During 2004, the Jupiter Icy Moons Orbiter project, a part of NASA's Project Prometheus, continued efforts to develop electric propulsion technologies. These technologies addressed the challenges of propelling a spacecraft to several moons of Jupiter. Specific challenges include high power, high specific impulse, long lived ion thrusters, high power/high voltage power processors, accurate feed systems, and large propellant storage systems. Critical component work included high voltage insulators and isolators as well as ensuring that the thruster materials and components could operate in the substantial Jupiter radiation environment. A review of these developments along with future plans is discussed.

Using 3D Spectroscopy to Probe the Orbital Structure of Composite Bulges

NASA Astrophysics Data System (ADS)

Erwin, Peter; Saglia, Roberto; Thomas, Jens; Fabricius, Maximilian; Bender, Ralf; Rusli, Stephanie; Nowak, Nina; Beckman, John E.; Vega Beltrán, Juan Carlos

2015-02-01

Detailed imaging and spectroscopic analysis of the centers of nearby S0 and spiral galaxies shows the existence of ``composite bulges'', where both classical bulges and disky pseudobulges coexist in the same galaxy. As part of a search for supermassive black holes in nearby galaxy nuclei, we obtained VLT-SINFONI observations in adaptive-optics mode of several of these galaxies. Schwarzschild dynamical modeling enables us to disentangle the stellar orbital structure of the different central components, and to distinguish the differing contributions of kinematically hot (classical bulge) and kinematically cool (pseudobulge) components in the same galaxy.

Air-Cored Linear Induction Motor for Earth-to-Orbit Systems

NASA Technical Reports Server (NTRS)

Zabar, Zivan; Levi, Enrico; Birenbaum, Leo

1996-01-01

The need for lowering the cost of Earth-to-Orbit (ETO) launches has prompted consideration of electromagnetic launchers. A preliminary design based on the experience gained in an advanced type of coilgun and on innovative ideas shows that such a launcher is technically feasible with almost off-the-shelf components.

Space shuttle: Static stability and control investigation of NR/GD delta wing booster (B-20) and delta wing orbiter (134D), volume 4

NASA Technical Reports Server (NTRS)

Allen, E. C., Jr.; Eder, F. W.

1972-01-01

Test results of booster and orbiter models of various component buildup configurations are reported. Dataset Collation Sheets, which give a complete summary of the configurations, are presented along with a description of the test facility. Data reduction procedures are described.

MSFC Skylab Orbital Workshop, volume 4. [design and development of life support systems

NASA Technical Reports Server (NTRS)

1974-01-01

The design and development of specific systems on the Skylab Orbital Laboratory are discussed. The subjects considered are: (1) pressure garment conditioning system, (2) stowage system, (3) ground support equipment systems, and (4) marking systems illustrations of the system components are provided. Results of performance tests are discussed.

Design of a scientific probe for obtaining Mars surface material

NASA Technical Reports Server (NTRS)

Baker, Miles; Deyerl, Eric; Gibson, Tim; Langberg, Bob; Yee, Terrance (Editor)

1990-01-01

The objective is to return a 1 Kg Martian soil sample from the surface of Mars to a mothership in a 60 km Mars orbit. Given here is information on the mission profile, the structural design and component placement, thermal control and guidance, propulsion systems, orbital mechanics, and specialized structures.

Development of experimental facilities for processing metallic crystals in orbit

NASA Technical Reports Server (NTRS)

Duncan, Bill J.

1990-01-01

This paper discusses the evolution, current status, and planning for facilities to exploit the microgravity environment of earth orbit in applied metallic materials science. Space-Shuttle based facilities and some precursor flight programs are reviewed. Current facility development programs and planned Space Station furnace capabilities are described. The reduced gravity levels available in earth orbit allow the processing of metallic materials without the disturbing influence of gravitationally induced thermal convection, stratification due to density differences in sample components, or the effects of hydrostatic pressure.

On-Orbit Calibration of a Multi-Spectral Satellite Satellite Sensor Using a High Altitude Airborne Imaging Spectrometer

NASA Technical Reports Server (NTRS)

Green, R. O.; Shimada, M.

1996-01-01

Earth-looking satellites must be calibrated in order to quantitatively measure and monitor components of land, water and atmosphere of the Earth system. The inevitable change in performance due to the stress of satellite launch requires that the calibration of a satellite sensor be established and validated on-orbit. A new approach to on-orbit satellite sensor calibration has been developed using the flight of a high altitude calibrated airborne imaging spectrometer below a multi-spectral satellite sensor.

International Space Station (ISS)

NASA Image and Video Library

2001-09-16

The setting sun and the thin blue airglow line at Earth's horizon was captured by the International Space Station's (ISS) Expedition Three crewmembers with a digital camera. Some of the Station's components are silhouetted in the foreground. The crew was launched aboard the Space Shuttle Orbiter Discovery STS-105 mission, on August 10, 2001, replacing the Expedition Two crew. After marning the orbiting ISS for 128 consecutive days, the three returned to Earth on December 17, 2001, aboard the STS-108 mission Space Shuttle Orbiter Endeavour.

Artist's drawing of internal arrangement of orbiting Apollo & Soyuz crafts

NASA Image and Video Library

1974-12-01

S74-05269 (December 1974) --- An artist?s drawing illustrating the internal arrangement of the Apollo and Soyuz spacecraft in Earth orbit in a docked configuration. The three American Apollo crewmen and the two Soviet Soyuz crewmen will transfer to each other?s spacecraft during the July 1975 ASTP mission. The four Apollo-Soyuz Test Project visible components are, left to right, the Apollo Command Module, the Docking Module, the Soyuz Orbital Module and the Soyuz Descent Vehicle.

Orbiter electrical equipment utilization baseline

NASA Technical Reports Server (NTRS)

1980-01-01

The baseline for utilization of Orbiter electrical equipment in both electrical and Environmental Control and Life Support System (ECLSS) thermal analyses is established. It is a composite catalog of Space Shuttle equipment, as defined in the Shuttle Operational Data Book. The major functions and expected usage of each component type are described. Functional descriptions are designed to provide a fundamental understanding of the Orbiter electrical equipment, to insure correlation of equipment usage within nominal analyses, and to aid analysts in the formulation of off-nominal, contingency analyses.

The first multi-color photometric study of the short-period contact Eclipsing Binary DE Lyn

NASA Astrophysics Data System (ADS)

Hashimoto, Amanda; Zhang, Liyun; Han, Xianming L.; Hongpeng, Lu; Wang, Daimei

2016-01-01

We observed the contact eclipsing binary of DE Lyn using SARA 0.9 meter telescope at Kitt Peak National Observatory on February 9, 11, and 27, 2015. In this study, we obtained the first full phase coverage BVRI CCD light curves, analyzed the orbital period variation, and extracted the orbital parameters. We calculated the linear and quadratic ephemeris, and thereby found that DE Lyn has a decreasing orbital period rate of -5.1(±0.4)×10-7 days/year. We believe this decreasing trend is the result of the more massive component (secondary) transferring mass to the less massive component (primary), and we obtained a mass transfer rate of dm/dt = 7.06×10-7M⊙/year. By using the updated Wilson & Devinney program, we found the orbital parameters of DE Lyn, which, in turn, enabled us to calculate the low degree of contact factor as f = 9.02(± 0.01)%. Its degree of contact will continue to increase and will evolve into an over-contact system.

The first multi-color photometric study of the short-period contact eclipsing binary DE Lyn

NASA Astrophysics Data System (ADS)

Hashimoto, Amanda; Zhang, Liyun; Han, Xianming L.; Lu, Hongpeng; Wang, Daimei

2016-05-01

We observed the contact eclipsing binary of DE Lyn using SARA 0.9 m telescope at Kitt Peak National Observatory on February 9, 11, and 27, 2015. In this study, we obtained the first full phase coverage BVRI CCD light curves, analyzed the orbital period variation, and extracted the orbital parameters. We calculated the linear and quadratic ephemeris, and thereby found that DE Lyn has a decreasing orbital period rate of - 5.1(± 0.4) × 10-7 days/year. We assume this decreasing trend is the result of the more massive component (secondary) transferring mass to the less massive component (primary), and we obtained a mass transfer rate of dm / dt = 7.06 ×10-7M⊙ /year . By using the updated Wilson & Devinney program, we found the orbital parameters of DE Lyn, which, in turn, enabled us to calculate the low degree of contact factor as f = 9.02(± 0.01)%. In the future, its degree of contact will continue to increase and will evolve into an over-contact system.

The Be Binary δ Scorpii and Its 2011 Periastron Passage

NASA Astrophysics Data System (ADS)

Miroshnichenko, A. S.; Manset, N.; Pasechnik, A. V.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Ribeiro, J. M.; Fernando, A.; Garrel, T.; Knapen, J. H.; Buil, C.; Heathcote, B.; Pollmann, E.; Thizy, O.; Eversberg, T.; Reinecke, N.; Martin, J.; Okazaki, A. T.; Gandet, T. L.; Gvaramadze, V. V.; Zharikov, S. V.

2012-12-01

δ Scorpii is an unusual Be binary system. The binarity was discovered by interferometry in the 1970's and only confirmed by radial velocity measurements during the periastron passage in September 2000, when the primary component became a Be star. The components brightness and mass suggest that both are normal B-type stars. However, the large orbital eccentricity (e = 0.94) is highly uncommon, as most such Be binaries have circular orbits. The orbital period, only recently constrained by interferometry at 10.81 years, needed confirmation from spectroscopy during the last periastron passage in July 2011. The periastron observing campaign that involved professionals and amateurs resulted in obtaining several hundreds of spectra during the period of a large radial velocity change compared to only thirty obtained in 2000. Along with a determination of the orbital period accurate to 3-4 days, the radial velocity curve was found to be more complicated than one expected from just a binary system. I will briefly review the primary's disk development followed by a discussion of the recent observations. Implications for the system properties and ideas for future observations will be presented.

Modeling L2,3-Edge X-ray Absorption Spectroscopy with Real-Time Exact Two-Component Relativistic Time-Dependent Density Functional Theory.

PubMed

Kasper, Joseph M; Lestrange, Patrick J; Stetina, Torin F; Li, Xiaosong

2018-04-10

X-ray absorption spectroscopy is a powerful technique to probe local electronic and nuclear structure. There has been extensive theoretical work modeling K-edge spectra from first principles. However, modeling L-edge spectra directly with density functional theory poses a unique challenge requiring further study. Spin-orbit coupling must be included in the model, and a noncollinear density functional theory is required. Using the real-time exact two-component method, we are able to variationally include one-electron spin-orbit coupling terms when calculating the absorption spectrum. The abilities of different basis sets and density functionals to model spectra for both closed- and open-shell systems are investigated using SiCl 4 and three transition metal complexes, TiCl 4 , CrO 2 Cl 2 , and [FeCl 6 ] 3- . Although we are working in the real-time framework, individual molecular orbital transitions can still be recovered by projecting the density onto the ground state molecular orbital space and separating contributions to the time evolving dipole moment.

Magnetorotational Instability in Eccentric Disks

NASA Astrophysics Data System (ADS)

Chan, Chi-Ho; Krolik, Julian H.; Piran, Tsvi

2018-03-01

Eccentric disks arise in such astrophysical contexts as tidal disruption events, but it is unknown whether the magnetorotational instability (MRI), which powers accretion in circular disks, operates in eccentric disks as well. We examine the linear evolution of unstratified, incompressible MRI in an eccentric disk orbiting a point mass. We consider vertical modes of wavenumber k on a background flow with uniform eccentricity e and vertical Alfvén speed {v}{{A}} along an orbit with mean motion n. We find two mode families, one with dominant magnetic components, the other with dominant velocity components. The former is unstable at {(1-e)}3 {f}2≲ 3, where f\\equiv {{kv}}{{A}}/n, and the latter at e ≳ 0.8. For f 2 ≲ 3, MRI behaves much like in circular disks, but the growth per orbit declines slowly with increasing e; for f 2 ≳ 3, modes grow by parametric amplification, which is resonant for 0 < e ≪ 1. MRI growth and the attendant angular momentum and energy transport happen chiefly near pericenter, where orbital shear dominates magnetic tension.

Replacement of Atlantis', OV-104's, right orbital maneuvering system pod

NASA Technical Reports Server (NTRS)

1988-01-01

Atlantis', Orbiter Vehicle (OV) 104's, right orbital maneuvering system (OMS) pod (RP01) is placed in a checkout cell at Kennedy Space Center's (KSC's) Hypergolic Maintenance Facility (HMF). Technicians steady OMS mounted on ground handling cart as third technician, standing on ladder, secures support frame. At the HMF, a group of specially-equipped buildings in the KSC Industrial Area, the OMS pods are undergoing extensive processing, including removal of certain components that will undergo modification at vendor facilities prior to the Shuttle's return to flight. The OMS pods are bolted to the aft fuselage of the orbiter and contain the engines and thrusters used to maneuver the spaceship in orbit. View provided by KSC with alternate number KSC-87PC-93.

Advanced interferometric synthetic aperture radar (InSAR) time series analysis using interferograms of multiple-orbit tracks: A case study on Miyake-jima

NASA Astrophysics Data System (ADS)

Ozawa, Taku; Ueda, Hideki

2011-12-01

InSAR time series analysis is an effective tool for detecting spatially and temporally complicated volcanic deformation. To obtain details of such deformation, we developed an advanced InSAR time series analysis using interferograms of multiple-orbit tracks. Considering only right- (or only left-) looking SAR observations, incidence directions for different orbit tracks are mostly included in a common plane. Therefore, slant-range changes in their interferograms can be expressed by two components in the plane. This approach estimates the time series of their components from interferograms of multiple-orbit tracks by the least squares analysis, and higher accuracy is obtained if many interferograms of different orbit tracks are available. Additionally, this analysis can combine interferograms for different incidence angles. In a case study on Miyake-jima, we obtained a deformation time series corresponding to GPS observations from PALSAR interferograms of six orbit tracks. The obtained accuracy was better than that with the SBAS approach, demonstrating its effectiveness. Furthermore, it is expected that higher accuracy would be obtained if SAR observations were carried out more frequently in all orbit tracks. The deformation obtained in the case study indicates uplift along the west coast and subsidence with contraction around the caldera. The speed of the uplift was almost constant, but the subsidence around the caldera decelerated from 2009. A flat deformation source was estimated near sea level under the caldera, implying that deceleration of subsidence was related to interaction between volcanic thermal activity and the aquifer.

Earth Orbiter 1: Wideband Advanced Recorder and Processor (WARP)

NASA Technical Reports Server (NTRS)

Smith, Terry; Kessler, John

1999-01-01

An advanced on-board spacecraft data system component is presented. The component is computer-based and provides science data acquisition, processing, storage, and base-band transmission functions. Specifically, the component is a very high rate solid state recorder, serving as a pathfinder for achieving the data handling requirements of next-generation hyperspectral imaging missions.

Orbital Motion of Young Binaries in Ophiuchus and Upper Centaurus–Lupus

NASA Astrophysics Data System (ADS)

Schaefer, G. H.; Prato, L.; Simon, M.

2018-03-01

We present measurements of the orbital positions and flux ratios of 17 binary and triple systems in the Ophiuchus star-forming region and the Upper Centaurus–Lupus cluster based on adaptive optics imaging at the Keck Observatory. We report the detection of visual companions in MML 50 and MML 53 for the first time, as well as the possible detection of a third component in WSB 21. For six systems in our sample, our measurements provide a second orbital position following their initial discoveries over a decade ago. For eight systems with sufficient orbital coverage, we analyze the range of orbital solutions that fit the data. Ultimately, these observations will help provide the groundwork toward measuring precise masses for these pre-main-sequence stars and understanding the distribution of orbital parameters in young multiple systems.

BinCat: a Catalog of Nearby Binary Stars with Tools for Calculating Light-Leakage for Direct Imaging Missions

NASA Astrophysics Data System (ADS)

Holte, Elias Peter; Sirbu, Dan; Belikov, Ruslan

2018-01-01

Binary stars have been largely left out of direct imaging surveys for exoplanets, specifically for earth-sized planets in their star's habitable zone. Utilizing new direct imaging techniques brings us closer to being able to detect earth-like exoplanets around binary stars. In preparation for the upcoming WFIRST mission and other direct imaging-capable missions (HabEx, LUVIOR) it is important to understand the expected science yield resulting from the implementation of these imaging techniques. BinCat is a catalog of binary systems within 30 parsecs to be used as a target list for future direct imaging missions. There is a non-static component along with BinCat that allows researchers to predict the expected light-leakage between a binary component and its off-axis companion (a value critical to the aforementioned techniques) at any epoch. This is accomplished by using orbital elements from the Sixth Orbital Catalog to model the orbits of the binaries. The software was validated against the historical data used to generate the orbital parameters. When orbital information is unknown or the binaries are purely optical the proper motion of the pair taken from the Washington Double Star catalog is integrated in time to estimate expected light-leakage.

Asiago eclipsing binaries program IV. SZ Camelopardalis, a β Cephei pulsator in a quadruple, eclipsing system

NASA Astrophysics Data System (ADS)

Tamajo, E.; Munari, U.; Siviero, A.; Tomasella, L.; Dallaporta, S.

2012-03-01

We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P = 2.7 days in a long orbit (~55 yrs) around a non-eclipsing SB1 pair of orbital period P = 2.8 days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BVIC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a β Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is (0.33265 ± 0.00005) days and the observed total amplitude in the B band is (0.0105 ± 0.0005) mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution. Full Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A139

Precision ephemerides for gravitational-wave searches - III. Revised system parameters of Sco X-1

NASA Astrophysics Data System (ADS)

Wang, L.; Steeghs, D.; Galloway, D. K.; Marsh, T.; Casares, J.

2018-06-01

Neutron stars in low-mass X-ray binaries are considered promising candidate sources of continuous gravitational-waves. These neutron stars are typically rotating many hundreds of times a second. The process of accretion can potentially generate and support non-axisymmetric distortions to the compact object, resulting in persistent emission of gravitational-waves. We present a study of existing optical spectroscopic data for Sco X-1, a prime target for continuous gravitational-wave searches, with the aim of providing revised constraints on key orbital parameters required for a directed search with advanced-LIGO data. From a circular orbit fit to an improved radial velocity curve of the Bowen emission components, we derived an updated orbital period and ephemeris. Centre of symmetry measurements from the Bowen Doppler tomogram yield a centre of the disc component of 90 km s-1, which we interpret as a revised upper limit to the projected orbital velocity of the NS K1. By implementing Monte Carlo binary parameter calculations, and imposing new limits on K1 and the rotational broadening, we obtained a complete set of dynamical system parameter constraints including a new range for K1 of 40-90 km s-1. Finally, we discussed the implications of the updated orbital parameters for future continuous-waves searches.

ξTauri: a unique laboratory to study the dynamic interaction in a compact hierarchical quadruple system

NASA Astrophysics Data System (ADS)

Nemravová, J. A.; Harmanec, P.; Brož, M.; Vokrouhlický, D.; Mourard, D.; Hummel, C. A.; Cameron, C.; Matthews, J. M.; Bolton, C. T.; Božić, H.; Chini, R.; Dembsky, T.; Engle, S.; Farrington, C.; Grunhut, J. H.; Guenther, D. B.; Guinan, E. F.; Korčáková, D.; Koubský, P.; Kříček, R.; Kuschnig, R.; Mayer, P.; McCook, G. P.; Moffat, A. F. J.; Nardetto, N.; Prša, A.; Ribeiro, J.; Rowe, J.; Rucinski, S.; Škoda, P.; Šlechta, M.; Tallon-Bosc, I.; Votruba, V.; Weiss, W. W.; Wolf, M.; Zasche, P.; Zavala, R. T.

2016-10-01

Context. Compact hierarchical systems are important because the effects caused by the dynamical interaction among its members occur ona human timescale. These interactions play a role in the formation of close binaries through Kozai cycles with tides. One such system is ξ Tauri: it has three hierarchical orbits: 7.14 d (eclipsing components Aa, Ab), 145 d (components Aa+Ab, B), and 51 yr (components Aa+Ab+B, C). Aims: We aim to obtain physical properties of the system and to study the dynamical interaction between its components. Methods: Our analysis is based on a large series of spectroscopic photometric (including space-borne) observations and long-baseline optical and infrared spectro-interferometric observations. We used two approaches to infer the system properties: a set of observation-specific models, where all components have elliptical trajectories, and an N-body model, which computes the trajectory of each component by integrating Newton's equations of motion. Results: The triple subsystem exhibits clear signs of dynamical interaction. The most pronounced are the advance of the apsidal line and eclipse-timing variations. We determined the geometry of all three orbits using both observation-specific and N-body models. The latter correctly accounted for observed effects of the dynamical interaction, predicted cyclic variations of orbital inclinations, and determined the sense of motion of all orbits. Using perturbation theory, we demonstrate that prominent secular and periodic dynamical effects are explainable with a quadrupole interaction. We constrained the basic properties of all components, especially of members of the inner triple subsystem and detected rapid low-amplitude light variations that we attribute to co-rotating surface structures of component B. We also estimated the radius of component B. Properties of component C remain uncertain because of its low relative luminosity. We provide an independent estimate of the distance to the system. Conclusions: The accuracy and consistency of our results make ξ Tau an excellent test bed for models of formation and evolution of hierarchical systems. Full Tables D.1-D.7 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/594/A55Based on data from the MOST satellite, a former Canadian Space Agency mission, jointly operated by Microsatellite Systems Canada Inc. (MSCI; formerly Dynacon Inc.), the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.

Particle orbits in two-dimensional equilibrium models for the magnetotail

NASA Technical Reports Server (NTRS)

Karimabadi, H.; Pritchett, P. L.; Coroniti, F. V.

1990-01-01

Assuming that there exist an equilibrium state for the magnetotail, particle orbits are investigated in two-dimensional kinetic equilibrium models for the magnetotail. Particle orbits in the equilibrium field are compared with those calculated earlier with one-dimensional models, where the main component of the magnetic field (Bx) was approximated as either a hyperbolic tangent or a linear function of z with the normal field (Bz) assumed to be a constant. It was found that the particle orbits calculated with the two types of models are significantly different, mainly due to the neglect of the variation of Bx with x in the one-dimensional fields.

Using the orbiting companion to trace WR wind structures in the 29d WC8d + O8-9IV binary CV Ser

NASA Astrophysics Data System (ADS)

David-Uraz, Alexandre; Moffat, Anthony F. J.

2011-07-01

We have used continuous, high-precision, broadband visible photometry from the MOST satellite to trace wind structures in the WR component of CV Ser over more than a full orbit. Most of the small-scale light-curve variations are likely due to extinction by clumps along the line of sight to the O companion as it orbits and shines through varying columns of the WR wind. Parallel optical spectroscopy from the Mont Megantic Observatory is used to refine the orbital and wind-collision parameters, as well as to reveal line emission from clumps.

The orbiter mate/demate device

NASA Technical Reports Server (NTRS)

Miller, A. J.; Binkley, W. H.

1985-01-01

The numerous components and systems of the space shuttle orbiter mate/demate device (MDD) are discussed. Special emphasis is given, mechanisms and mechanical systems to discuss in general their requirements, functions, and design; and, where applicable, to relate any unusual problems encountered during the initial concept studies, final design, and construction are discussed. The MDD and its electrical, machinery, and mechanical systems, including the main hoisting system, power operated access service platform, wind restrain and adjustment mechanism, etc., were successfully designed and constructed. The MDD was used routinely during the initial orbiter-747 approach and landing test and the more recent orbiter flight tests recovery and mate operations.

Analytical formulation of orbiter-payload models coupled by trunnion joints with Coulomb friction

NASA Technical Reports Server (NTRS)

Liu, Frank C.

1987-01-01

An orbiter and its payload substructure are linked together by five trunnion joints which have thirty degrees-of-freedom. Geometric compatibility conditions require fourteen of the interface physical coordinates of the orbiter and payload to be equal to each other and the remaining sixteen are free to have relative motions under Coulomb friction. The component modes synthesis method using fourteen inertia relief attachment modes for the formulation of the coupled system is presented. The exact nonlinear friction function is derived based on the characteristics of the joints. Formulation is applicable to an orbiter that carries any number of payload substructures.

Analytical formulation of orbiter-payload coupled by trunnion joints with Coulomb friction

NASA Technical Reports Server (NTRS)

Liu, Frank C.

1986-01-01

An orbiter and its payload substructure are linked together by five trunnion joints which have thirty degrees-of-freedom. Geometric compatibility conditions require fourteen of the interface physical coordinates of the orbiter and payload to be equal to each other and the remaining sixteen are free to have relative motions under Coulomb friction. The component modes synthesis method using fourteen inertia relief attachment modes for the formulation of the coupled system is presented. The exact nonlinear friction function is derived based on the characteristics of the joints. Formulation is applicable to an orbiter that carries any number of payload substructures.

Spin and charge controlled by antisymmetric spin-orbit coupling in a triangular-triple-quantum-dot Kondo system

NASA Astrophysics Data System (ADS)

Koga, M.; Matsumoto, M.; Kusunose, H.

2018-05-01

We study a local antisymmetric spin-orbit (ASO) coupling effect on a triangular-triple-quantum-dot (TTQD) system as a theoretical proposal for a new application of the Kondo physics to nanoscale devices. The electric polarization induced by the Kondo effect is strongly correlated with the spin configurations and molecular orbital degrees of freedom in the TTQD. In particular, an abrupt sign reversal of the emergent electric polarization is associated with a quantum critical point in a magnetic field, which can also be controlled by the ASO coupling that changes the mixing weight of different orbital components in the TTQD ground state.

Retrieval Analysis of the Emission Spectrum of WASP-12b: Sensitivity of Outcomes to Prior Assumptions and Implications for Formation History

NASA Astrophysics Data System (ADS)

Oreshenko, Maria; Lavie, Baptiste; Grimm, Simon L.; Tsai, Shang-Min; Malik, Matej; Demory, Brice-Olivier; Mordasini, Christoph; Alibert, Yann; Benz, Willy; Quanz, Sascha P.; Trotta, Roberto; Heng, Kevin

2017-09-01

We analyze the emission spectrum of the hot Jupiter WASP-12b using our HELIOS-R retrieval code and HELIOS-K opacity calculator. When interpreting Hubble and Spitzer data, the retrieval outcomes are found to be prior-dominated. When the prior distributions of the molecular abundances are assumed to be log-uniform, the volume mixing ratio of HCN is found to be implausibly high. A VULCAN chemical kinetics model of WASP-12b suggests that chemical equilibrium is a reasonable assumption even when atmospheric mixing is implausibly rigorous. Guided by (exo)planet formation theory, we set Gaussian priors on the elemental abundances of carbon, oxygen, and nitrogen with the Gaussian peaks being centered on the measured C/H, O/H, and N/H values of the star. By enforcing chemical equilibrium, we find substellar O/H and stellar to slightly superstellar C/H for the dayside atmosphere of WASP-12b. The superstellar carbon-to-oxygen ratio is just above unity, regardless of whether clouds are included in the retrieval analysis, consistent with Madhusudhan et al. Furthermore, whether a temperature inversion exists in the atmosphere depends on one’s assumption for the Gaussian width of the priors. Our retrieved posterior distributions are consistent with the formation of WASP-12b in a solar-composition protoplanetary disk, beyond the water iceline, via gravitational instability or pebble accretion (without core erosion) and migration inward to its present orbital location via a disk-free mechanism, and are inconsistent with both in situ formation and core accretion with disk migration, as predicted by Madhusudhan et al. We predict that the interpretation of James Webb Space Telescope WASP-12b data will not be prior-dominated.

Detection of planet candidates around K giants. HD 40956, HD 111591, and HD 113996

NASA Astrophysics Data System (ADS)

Jeong, G.; Lee, B.-C.; Han, I.; Omiya, M.; Izumiura, H.; Sato, B.; Harakawa, H.; Kambe, E.; Mkrtichian, D.

2018-02-01

Aims: The purpose of this paper is to detect and investigate the nature of long-term radial velocity (RV) variations of K-type giants and to confirm planetary companions around the stars. Methods: We have conducted two planet search programs by precise RV measurement using the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) and the 1.88 m telescope at Okayama Astrophysical Observatory (OAO). The BOAO program searches for planets around 55 early K giants. The OAO program is looking for 190 G-K type giants. Results: In this paper, we report the detection of long-period RV variations of three K giant stars, HD 40956, HD 111591, and HD 113996. We investigated the cause of the observed RV variations and conclude the substellar companions are most likely the cause of the RV variations. The orbital analyses yield P = 578.6 ± 3.3 d, m sin i = 2.7 ± 0.6 MJ, a = 1.4 ± 0.1 AU for HD 40956; P = 1056.4 ± 14.3 d, m sin i = 4.4 ± 0.4 MJ, a = 2.5 ± 0.1 AU for HD 111591; P = 610.2 ± 3.8 d, m sin i = 6.3 ± 1.0 MJ, a = 1.6 ± 0.1 AU for HD 113996. Based on observations made with the BOES at BOAO in Korea and HIDES at OAO in Japan.Tables 3-5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A3

Search for Exoplanets around Northern Circumpolar Stars. II. The Detection of Radial Velocity Variations in M Giant Stars HD 36384, HD 52030, and HD 208742

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Byeong-Cheol; Jeong, Gwanghui; Han, Inwoo

2017-07-20

We present the detection of long-period RV variations in HD 36384, HD 52030, and HD 208742 by using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) for the precise radial velocity (RV) survey of about 200 northern circumpolar stars. Analyses of RV data, chromospheric activity indicators, and bisector variations spanning about five years suggest that the RV variations are compatible with planet or brown dwarf companions in Keplerian motion. However, HD 36384 shows photometric variations with a period very close to that of RV variations as well as amplitude variations in the weighted wavelet Z-transform (WWZ) analysis, which argues thatmore » the RV variations in HD 36384 are from the stellar pulsations. Assuming that the companion hypothesis is correct, HD 52030 hosts a companion with minimum mass 13.3 M {sub Jup} orbiting in 484 days at a distance of 1.2 au. HD 208742 hosts a companion of 14.0 M {sub Jup} at 1.5 au with a period of 602 days. All stars are located at the asymptotic giant branch (AGB) stage on the H–R diagram after undergoing the helium flash and leaving the giant clump.With stellar radii of 53.0 R {sub ⊙} and 57.2 R {sub ⊙} for HD 52030 and HD 208742, respectively, these stars may be the largest yet, in terms of stellar radius, found to host substellar companions. However, given possible RV amplitude variations and the fact that these are highly evolved stars, the planet hypothesis is not yet certain.« less

Retrieval Analysis of the Emission Spectrum of WASP-12b: Sensitivity of Outcomes to Prior Assumptions and Implications for Formation History

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oreshenko, Maria; Lavie, Baptiste; Grimm, Simon L.

We analyze the emission spectrum of the hot Jupiter WASP-12b using our HELIOS-R retrieval code and HELIOS-K opacity calculator. When interpreting Hubble and Spitzer data, the retrieval outcomes are found to be prior-dominated. When the prior distributions of the molecular abundances are assumed to be log-uniform, the volume mixing ratio of HCN is found to be implausibly high. A VULCAN chemical kinetics model of WASP-12b suggests that chemical equilibrium is a reasonable assumption even when atmospheric mixing is implausibly rigorous. Guided by (exo)planet formation theory, we set Gaussian priors on the elemental abundances of carbon, oxygen, and nitrogen with themore » Gaussian peaks being centered on the measured C/H, O/H, and N/H values of the star. By enforcing chemical equilibrium, we find substellar O/H and stellar to slightly superstellar C/H for the dayside atmosphere of WASP-12b. The superstellar carbon-to-oxygen ratio is just above unity, regardless of whether clouds are included in the retrieval analysis, consistent with Madhusudhan et al. Furthermore, whether a temperature inversion exists in the atmosphere depends on one’s assumption for the Gaussian width of the priors. Our retrieved posterior distributions are consistent with the formation of WASP-12b in a solar-composition protoplanetary disk, beyond the water iceline, via gravitational instability or pebble accretion (without core erosion) and migration inward to its present orbital location via a disk-free mechanism, and are inconsistent with both in situ formation and core accretion with disk migration, as predicted by Madhusudhan et al. We predict that the interpretation of James Webb Space Telescope WASP-12b data will not be prior-dominated.« less

Radial velocity variability and stellar properties of FGK stars in the cores of NGC 2516 and NGC 2422

NASA Astrophysics Data System (ADS)

Bailey, John I.; Mateo, Mario; White, Russel J.; Shectman, Stephen A.; Crane, Jeffrey D.

2018-04-01

We present multi-epoch high-dispersion optical spectra obtained with the Michigan/Magellan Fibre System of 126 and 125 Sun-like stars in the young clusters NGC 2516 (141 Myr) and NGC 2422 (73 Myr). We determine stellar properties including radial velocity (RV), Teff, [Fe/H], [α/Fe] and the line-of-sight rotation rate, vrsin (i), from these spectra. Our median RV precision of 80 m s-1 on individual epochs that span a temporal baseline of 1.1 yr enables us to investigate membership and stellar binarity, and to search for sub-stellar companions. We determine membership probabilities and RV variability probabilities for our sample along with candidate companion orbital periods for a select subset of stars. In NGC 2516, we identified 81 RV members, 27 spectroscopic binaries (17 previously identified as photometric binaries) and 16 other stars that show significant RV variability after accounting for average stellar jitter at the 74 m s-1 level. In NGC 2422, we identify 57 members, 11 spectroscopic binaries and three other stars that show significant RV variability after accounting for an average jitter of 138 m s-1. We use Monte Carlo simulations to verify our stellar jitter measurements, determine the proportion of exoplanets and stellar companions to which we are sensitive, and estimate companion-mass limits for our targets. We also report mean cluster metallicity, velocity and velocity dispersion based on our member targets. We identify 58 non-member stars as RV variables, 24 of which have RV amplitudes that imply stellar or brown-dwarf mass companions. Finally, we note the discovery of a separate RV clustering of stars in our NGC 2422 sample.

Interpretation of a Variable Reflection Nebula Associated with HBC 340 and HBC 341 in NGC 1333

NASA Astrophysics Data System (ADS)

Dahm, S. E.; Hillenbrand, L. A.

2017-11-01

We present multi-epoch, R-band imaging obtained from the Palomar Transient Factory of a small, fan-shaped reflection nebula in NGC 1333 that experiences prominent brightness fluctuations. Photometry of HBC 340 (K7e) and HBC 341 (M5e), a visual pair of late-type, young stellar objects lying near the apex of the nebula, demonstrates that while both are variable, the former has brightened by more than two magnitudes following a deep local minimum in 2014 September. Keck high-dispersion (R ˜ 45,000-66,000), optical spectroscopy of HBC 340 suggests that the protostar is a spectroscopic binary (HBC 340Aa + HBC 340Ab). Both HBC 340 and HBC 341 exhibit strong Hα and forbidden line emission, consistent with accretion and outflow. We conclude that the brightness fluctuations in the reflection nebula represent light echos produced by varying incident radiation emanating from HBC 340. The short-term variability observed in the protostar is attributed to irregular accretion activity, while correlated, dipping behavior on a several hundred day timescale may be due to eclipse-like events caused by orbiting circumstellar material. Archival Hubble Space Telescope imaging of the region reveals a second, faint (F814W ˜ 20.3 mag) companion to HBC 340 that lies 1.″02 (˜235 au) east of the protostar. If associated, this probable substellar mass object (20-50 Jupiter masses), HBC 340B, is likely unrelated to the observed brightness variations. The sustained brightening of HBC 340 since late 2014 can be explained by an EXor-like outburst, the recovery from a long duration eclipse event caused by obscuring circumstellar dust, or by the gradual removal of extincting material from along the line of sight. Our analysis here favors one of the extinction scenarios.

The First United States Microgravity Laboratory

NASA Technical Reports Server (NTRS)

Powers, C. Blake (Editor); Shea, Charlotte; Mcmahan, Tracy; Accardi, Denise; Mikatarian, Jeff

1991-01-01

The United States Microgravity Laboratory (USML-1) is one part of a science and technology program that will open NASA's next great era of discovery and establish the United States' leadership in space. A key component in the preparation for this new age of exploration, the USML-1 will fly in orbit for extended periods, providing greater opportunities for research in materials science, fluid dynamics, biotechnology, and combustion science. The major components of the USML-1 are the Crystal Growth Furnace, the Surface Tension Driven Convection Experiment (STDCE) Apparatus, and the Drop Physics Module. Other components of USML-1 include Astroculture, Generic Bioprocessing Apparatus, Extended Duration Orbiter Medical Project, Protein Crystal Growth, Space Acceleration Measurement System, Solid Surface Combustion Experiment, Zeolite Crystal Growth and Spacelab Glovebox provided by the European Space Agency.

The ss(bar sign) component of the proton and the strangeness magnetic moment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riska, D. O.; Zou, B. S.

2006-07-11

The implications of the empirical indications for a positive strangeness magnetic moment on the possible configurations of the uudss(bar sign) component of the proton are analysed. A positive value for {mu}s is obtained in the ss(bar sign) configuration where the uuds subsystem is in an orbitally excited state with [4]FS[22]F[22]S flavor-spin symmetry, which is likely to have the lowest energy. The configurations in which the s-bar is orbitally excited, which include the conventional K+{lambda}0 configuration, with exception of that in which the uuds component has spin 2, yield negative values for {mu}s. The hidden strangeness analogues of recently proposed quarkmore » cluster models for the {theta}+ pentaquark give differing signs for {mu}s.« less

The Multiple-component Binary Hyad, vA 351 - a Progress Report

NASA Astrophysics Data System (ADS)

Benedict, George Fritz; Franz, Otto G.; Wasserman, Lawrence H.

2017-06-01

We extend results first announced by Franz et al. (1998) in the abstract, http://adsabs.harvard.edu/abs/1998AAS...19310207F ,that identified vA 351 = H346 in the Hyades as a multiple star system containing a white dwarf. With HST/FGS fringe tracking and scanning, spanning four years, we establish a parallax, relative orbit, and mass fraction for the A-B components, with a period, P~5.47y. With ground-based radial velocities from the McDonald Observatory Struve 2.1m telescope and Sandiford Spectrograph, spanning 14 years, we find that component B consists of BC, two M dwarf stars orbiting with a very short period (P(BC)~0.75 days), having a mass ratio C/B~0.94. We confirm that the total mass of the system can only be reconciled with the distance and component photometry by including a fainter, higher mass component, proposed to be a ~0.8Msun white dwarf. Thus, the quadruple system consists of three M dwarfs (A,B,C) and one white dwarf (D). The M dwarf masses and absolute magnitudes are consistent with the Benedict et al. (2016, http://adsabs.harvard.edu/abs/2016AJ....152..141B) lower Main Sequence Mass-Luminosity Relation. The radial velocity signal has so far yielded a signature only for the short-period BC orbital motion. Velocities from H-α and He I emission lines confirm the BC period from absorption lines, with similar (He I) and higher (H-α) velocity amplitudes.

Meteoroid/orbital debris impact damage predictions for the Russian space station MIR

NASA Technical Reports Server (NTRS)

Christiansen, E. L.; Hyde, J. L.; Lear, D.

1997-01-01

Components of the Mir space station have been exposed to the meteoroid/orbital debris (M/OD) environment for up to 11 years. During this period, no M/OD impact perforation of the pressure shell of the manned modules were reported. The NASA standard M/OD analysis code BUMPER was used to predict the probability of M/OD impact damage to various components of Mir. The analysis indicates a 1 in 2.2 chance that a M/OD impact would have caused a penetration resulting in a pressure leak of the Mir modules since its launch up to the February 1997. For the next five years, the estimated odds become 1 in 3. On an annual basis, penetration risks are 60 percent higher, on the average, in the next five years due to the larger size of Mir and the growth in the orbital debris population.

Modeling Minor Constituents of Europa's Atmosphere

NASA Astrophysics Data System (ADS)

Cassidy, T. A.; Johnson, R. E.

2007-12-01

A spacecraft orbiting Jupiter's moon Europa, of the sort considered by both ESA and NASA, would provide an opportunity to determine the composition and morphology of its tenuous atmosphere. Europa's atmosphere, though tenuous, has been detected by Earth-based telescopes. Its O2 atmosphere was detected from Earth orbit and its much thinner alkali atmosphere was detected by ground-based telescopes. Many other species are expected based on surface reflectance spectra, such as H2O, Sn, SO2, CO2, H2O2. I will discuss the issues involved in the modeling of these as-yet-undetected components. Previous theoretical studies and observations of the atmosphere produced important conclusions about the surface and its interaction with the Jovian magnetosphere. The modeling and detection of minor components could reveal much more. Of particular interest is the detectability of these species with an orbiting mass spectrometer or more distant light spectrometer.

Accounting of fundamental components of the rotation parameters of the Earth in the formation of a high-accuracy orbit of navigation satellites

NASA Astrophysics Data System (ADS)

Markov, Yu. G.; Mikhailov, M. V.; Pochukaev, V. N.

2012-07-01

An analysis of perturbing factors influencing the motion of a navigation satellite (NS) is carried out, and the degree of influence of each factor on the GLONASS orbit is estimated. It is found that fundamental components of the Earth's rotation parameters (ERP) are one substantial factor commensurable with maximum perturbations. Algorithms for the calculation of orbital perturbations caused by these parameters are given; these algorithms can be implemented in a consumer's equipment. The daily prediction of NS coordinates is performed on the basis of real GLONASS satellite ephemerides transmitted to a consumer, using the developed prediction algorithms taking the ERP into account. The obtained accuracy of the daily prediction of GLONASS ephemerides exceeds by tens of times the accuracy of the daily prediction performed using algorithms recommended in interface control documents.

Enhanced magneto-optical Kerr effect at Fe/insulator interfaces

NASA Astrophysics Data System (ADS)

Gu, Bo; Takahashi, Saburo; Maekawa, Sadamichi

2017-12-01

Using density functional theory calculations, we have found an enhanced magneto-optical Kerr effect in Fe/insulator interfaces. The results of our study indicate that interfacial Fe atoms in the Fe films have a low-dimensional nature, which causes the following two effects: (i) The diagonal component σx x of the optical conductivity decreases dramatically because the hopping integral for electrons between Fe atoms is suppressed by the low dimensionality. (ii) The off-diagonal component σx y of the optical conductivity does not change at low photon energies, but it is enhanced at photon energies around 2 eV, where we obtain enhanced orbital magnetic moments and spin-orbit correlations for the interfacial Fe atoms. A large Kerr angle develops in proportion to the ratio σx y/σx x . Our findings indicate an efficient way to enhance the effect of spin-orbit coupling at metal/insulator interfaces without using heavy elements.

Orbits and masses in the young triple system TWA 5

NASA Astrophysics Data System (ADS)

Köhler, R.; Ratzka, T.; Petr-Gotzens, M. G.; Correia, S.

2013-10-01

Aims: We aim to improve the orbital elements and determine the individual masses of the components in the triple system TWA 5. Methods: Five new relative astrometric positions in the H band were recorded with the adaptive optics system at the Very Large Telescope (VLT). We combine them with data from the literature and a measurement in the Ks band. We derive an improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use the third component, TWA 5B, as an astrometric reference to determine the motion of Aa and Ab around their center of mass and compute their mass ratio. Results: We find an orbital period of 6.03 ± 0.01 years and a semi-major axis of 63.7 ± 0.2 mas (3.2 ± 0.1 AU). With the trigonometric distance of 50.1 ± 1.8 pc, this yields a system mass of 0.9 ± 0.1 M⊙, where the error is dominated by the error of the distance. The dynamical mass agrees with the system mass predicted by a number of theoretical models if we assume that TWA5 is at the young end of the age range of the TW Hydrae association. We find a mass ratio of MAb/MAa = 1.3-0.4+0.6 , where the less luminous component Ab is more massive. This result is likely to be a consequence of the large uncertainties due to the limited orbital coverage of the observations. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 079.C-0103, 081.C-0393, 386.C-0205, 087.C-0209, 088.C-0046, 089.C-0167, and 090.C-0184.

Preliminary Orbit and Differential Photometry of the Nearby Flare Star CR Dra

NASA Astrophysics Data System (ADS)

Tamazian, Vakhtang S.; Docobo, José A.; Balega, Yuri Y.; Melikian, Norair D.; Maximov, Alexander F.; Malogolovets, Evgeny V.

2008-09-01

New speckle measurements with the 6 m telescope of the Special Astrophysical Observatory (Russia) and the first preliminary orbit of the nearby flare star CR Dra (=Gl 616.2; WDS 16171+5516; BLA 3) with a period of 4.04 yr and a semimajor axis of 0farcs148 are reported. The Hipparcos parallax of 48.36 ± 1.16 mas (distance 20.7 pc) leads to an unusually large total mass of 1.8 M sun for a couple of red dwarfs. Meanwhile, the application of the Baize-Romani algorithm resulted in a mass sum of 1.00 M sun and a dynamical parallax of 58.43 mas (17.4 pc), which sensibly differs from that of Hipparcos. For the first time, we measured the photometric magnitude difference between the components (1.8 mag and 1.4 mag in the V and R bands, respectively) and obtained individual brightness estimates for each of them. Independently of the adopted parallax type, standard mass-luminosity relationships applied to individual components yield a total mass less than 1.2 M sun. This lends support to the use of a dynamical parallax, which is a more reliable distance estimate until a third body is discovered and/or our reported preliminary orbit is sensibly changed. CR Dra belongs to a handful of resolved short-period flare binaries, representing an excellent target to calculate a very accurate (or even definitive) orbit and a dynamical mass on a short time span. The available photometric data reveal no plausible correlation between flaring activity of CR Dra and linear distance between the components on the orbital path. Follow-up observations are needed for more detailed study of a possible relationship between dynamical and astrophysical properties of CR Dra and other similar systems.

Direct observation of extrasolar planets and the development of the gemini planet imager integral field spectrograph

NASA Astrophysics Data System (ADS)

Chilcote, Jeffrey Kaplan

This thesis is focused on the development and testing of a new instrument capable of finding and characterizing recently-formed Jupiter-sized planets orbiting other stars. To observe these planets, I present the design, construction and testing of the Gemini Planet Imager (GPI) Integral Field Spectrograph (IFS). GPI is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. The GPI IFS utilizes an infrared transmissive lenslet array to sample a rectangular 2.7 x 2.7 arcsecond field of view and provide low-resolution spectra across five bands between 1 and 2.5 mum. The dispersing element can be replaced with a Wollaston prism to provide broadband polarimetry across the same five filter bands. The IFS construction was based at the University of California, Los Angeles in collaboration with the Universite de Montreal, Immervision and Lawrence Livermore National Laboratory. I will present performance results, from in-lab testing, of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). The IFS is a large, complex, cryogenic, optical system requiring several years of development and testing. I will present the design and integration of the mechanical and optical performance of the spectrograph optics. The IFS passed its pre-ship review in 2011 and was shipped to University of California, Santa Cruz for integration with the remaining sub-systems of GPI. The UCLA built GPI IFS was integrated with the rest of GPI and is delivering high quality spectral datacubes of GPI's coronagraphic field. Using the NIRC2 instrument located at the Keck Observatory, my collaborators and I observed the planetary companion to beta Pictoris in L' (3.5--4.1mum). Observations taken in the fall of 2009 and 2012 are used to find the location and inclination of the planet relative to the massive debris disk orbiting beta Pictoris. We find that the planet's orbit has a position angle on the sky of 211.9+/-0.4 degrees, making the planet misaligned by 2.9+/-0.5 degrees from the main disk, consistent with other observations that beta Pic b is misaligned with the main disk, and part of the misaligned inner disk. In 2009 & 2012 we find a projected orbital separation of 312.8 +/- 18.3 and 466.35 +/- 8.4 milliarcseconds consistent with an orbital period of ˜ 20 years, and a semi-major axis of ˜ 9 AU as found by Macintosh et al. (2014). During the first commissioning observations with the Gemini Planet Imager (GPI), my collaborators and I took the first H-band spectrum of the planetary companion to the nearby young star beta Pictoris. The spectrum has a resolving power of ˜ 45 and demonstrates the distinctive triangular shape of a cool substellar object with low surface gravity. Using atmospheric models, we find an effective temperature of 1650 +/- 50K and a surface gravity of log(g) = 4.0 +/- 0.25 (cgs units). These values agree well with predictions from planetary evolution models for a gas giant with mass between 10 and 12 MJup and age between 10 and 20 Myrs. The spectrum is very similar to a known low mass field brown dwarf but has more flux at the long wavelength end of the filters compared to models. Given the very high signal-to-noise of our spectrum this likely indicates additional physics such as patchy clouds that need to be included in the model.

A final look at LDEF electro-optic systems components

NASA Technical Reports Server (NTRS)

Blue, M. D.

1995-01-01

Postrecovery characteristics of LDEF electro-optic components from the GTRI tray are compared with their prelaunch characteristics and with the characteristics of similar components from related experiments. Components considered here include lasers, light-emitting diodes, semiconducting radiation detectors and arrays, optical substrates, filters, and mirrors, and specialized coatings. Our understanding of the physical effects resulting from low earth orbit are described, and guidelines and recommendations for component and materials choices are presented.

HIGH-RESOLUTION SPECTROSCOPY DURING ECLIPSE OF THE YOUNG SUBSTELLAR ECLIPSING BINARY 2MASS 0535-0546. II. SECONDARY SPECTRUM: NO EVIDENCE THAT SPOTS CAUSE THE TEMPERATURE REVERSAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohanty, Subhanjoy; Stassun, Keivan G., E-mail: s.mohanty@imperial.ac.uk, E-mail: keivan.stassun@vanderbilt.edu

2012-10-10

We present high-resolution optical spectra of the young brown dwarf eclipsing binary 2M0535-05, obtained during eclipse of the higher-mass (primary) brown dwarf. Combined with our previous spectrum of the primary alone (Paper I), the new observations yield the spectrum of the secondary alone. We investigate, through a differential analysis of the two binary components, whether cool surface spots are responsible for suppressing the temperature of the primary. In Paper I, we found a significant discrepancy between the empirical surface gravity of the primary and that inferred via fine analysis of its spectrum. Here we find precisely the same discrepancy inmore » surface gravity, both qualitatively and quantitatively. While this may again be ascribed to either cool spots or model opacity errors, it implies that cool spots cannot be responsible for preferentially lowering the temperature of the primary: if they were, spot effects on the primary spectrum should be preferentially larger, and they are not. The T{sub eff}'s we infer for the primary and secondary, from the TiO-{epsilon} bands alone, show the same reversal, in the same ratio, as is empirically observed, bolstering the validity of our analysis. In turn, this implies that if suppression of convection by magnetic fields on the primary is the fundamental cause of the T{sub eff} reversal, then it cannot be a local suppression yielding spots mainly on the primary (though both components may be equally spotted), but a global suppression in the interior of the primary. We briefly discuss current theories of how this might work.« less

THE LEECH EXOPLANET IMAGING SURVEY: ORBIT AND COMPONENT MASSES OF THE INTERMEDIATE-AGE, LATE-TYPE BINARY NO UMa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlieder, Joshua E.; Skemer, Andrew J.; Hinz, Philip

2016-02-10

We present high-resolution Large Binocular Telescope LBTI/LMIRcam images of the spectroscopic and astrometric binary NO UMa obtained as part of the LBT Interferometer Exozodi Exoplanet Common Hunt exoplanet imaging survey. Our H-, K{sub s}-, and L′-band observations resolve the system at angular separations <0.″09. The components exhibit significant orbital motion over a span of ∼7 months. We combine our imaging data with archival images, published speckle interferometry measurements, and existing spectroscopic velocity data to solve the full orbital solution and estimate component masses. The masses of the K2.0 ± 0.5 primary and K6.5 ± 0.5 secondary are 0.83 ± 0.02 M{sub ⊙} and 0.64 ± 0.02 M{sub ⊙},more » respectively. We also derive a system distance of d = 25.87 ± 0.02 pc and revise the Galactic kinematics of NO UMa. Our revised Galactic kinematics confirm NO UMa as a nuclear member of the ∼500 Myr old Ursa Major moving group, and it is thus a mass and age benchmark. We compare the masses of the NO UMa binary components to those predicted by five sets of stellar evolution models at the age of the Ursa Major group. We find excellent agreement between our measured masses and model predictions with little systematic scatter between the models. NO UMa joins the short list of nearby, bright, late-type binaries having known ages and fully characterized orbits.« less

OV Bootis: Forty Nights Of World-Wide Photometry

NASA Astrophysics Data System (ADS)

Patterson, Joseph; de Miguel, Enrique; Barret, Douglas; Brincat, Stephen; Boardman, James, Jr.; Buczynski, Denis; Campbell, Tut; Cejudo, David; Cook, Lew; Cook, Michael J.; Collins, Donald; Cooney, Walt; Dubois, Franky; Dvorak, Shawn; Halpern, Jules P.; Kroes, Anthony J.; Lemay, Damien; Licchelli, Domenico; Mankel, Dylan; Marshall, Matt; Novak, Rudolf; Oksanen, Arto; Roberts, George; Seargeant, Jim; Sears, Huei; Silcox, Austin; Slauson, Douglas; Stone, Geoff; Thorstensen, J. R.; Ulowetz, Joe; Vanmunster, Tonny; Wallgren, John; Wood, Matt

2017-06-01

Among the 1000 known cataclysmic variables, only one appears to belong to the "Galactic halo" - the Population II stars. We report round-the-world photometry of this star (OV Boo) during March-April 2017, when it staged its first certified dwarf-nova outburst. The star is remarkable for its short binary period (66 minutes), high proper motion, metal-poor composition, substellar secondary, sharp white-dwarf eclipses, and nonradial pulsations. Something for everybody...... and it even had the good manners to erupt in northern springtime, when it transits near local midnight. Move over, SS Cyg and WZ Sge; there's a new celebrity in town!

Precipitating Condensation Clouds in Substellar Atmospheres

NASA Technical Reports Server (NTRS)

Ackerman, Andrew S.; Marley, Mark S.; Gore, Warren J. (Technical Monitor)

2000-01-01

We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and precipitation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with previous methods. An adjustable parameter describing the efficiency of precipitation allows the new model to span the range of predictions from previous models. Calculations for the Jovian ammonia cloud are found to be consistent with observational constraints. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet.

The SOLA Team: A Star Formation Project To Study the Soul of Lupus with ALMA

NASA Astrophysics Data System (ADS)

De Gregorio-Monsalvo, Itziar; Saito, M.; Rodon, J.; Takahashi, S.

2017-06-01

The SOLA team is a multi-national and multi-wavelength collaboration composed by scientists with technical expertise in ALMA and in infrared and optical techniques. The aim of the team is to establish a low-mass star formation scenario based on the Lupus molecular clouds. In this talk I will present our unique catalog of pre-stellar and proto-stellar cores toward Lupus molecular clouds, the results on our latest studies in protoplanetary disks, as well as our ALMA Cycle 3 data aiming at testing the formation mechanism of sub-stellar objects in Lupus molecular clouds.

Reviews in Modern Astronomy: Vol. 16: The Cosmic Circuit of Matter

NASA Astrophysics Data System (ADS)

Schielicke, Reinhard E.

2003-08-01

The 16th volume in the annual series on recent developments and scientific progress in astronomy and astrophysics contains thirteen invited reviews presented during the International Scientific Conference of the Society on "The Cosmic Circuit of Matter", held in Berlin, Germany. Readers also learn about the lecture on the behaviour of stars by infrared interferometry given by Charles H. Townes, Berkeley, USA who was awarded the Karl Schwarzschild medal 2002. Further contributions on the topic provide, among other, the latest results on the Solar atmosphere, formation of stars, substellar objects, galaxies and clusters of galaxies.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is lowered toward a transporter. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Image and Video Library

2003-09-05

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is lowered toward a transporter. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

KENNEDY SPACE CENTER, FLA. - Technicians in the Orbiter Processing Facility oversee removal of one of two orbital maneuvering system (OMS) pods from Endeavour. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Image and Video Library

2003-09-05

KENNEDY SPACE CENTER, FLA. - Technicians in the Orbiter Processing Facility oversee removal of one of two orbital maneuvering system (OMS) pods from Endeavour. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility prepare to remove one of two orbital maneuvering system (OMS) pods from Endeavour. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Image and Video Library

2003-09-05

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility prepare to remove one of two orbital maneuvering system (OMS) pods from Endeavour. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is suspended overhead. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Image and Video Library

2003-09-05

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is suspended overhead. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is lowered onto a transporter. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Image and Video Library

2003-09-05

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, one of two orbital maneuvering system (OMS) pods removed from Endeavour is lowered onto a transporter. The OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts. OMS pods are removed during Orbiter Major Modifications. Once removed, the OMS pods undergo in-depth structural inspections, system checks and the thrusters are changed out.

NASA Research Center Contributions to Space Shuttle Return to Flight (SSRTF)

NASA Technical Reports Server (NTRS)

Cockrell, Charles E., Jr.; Barnes, Robert S.; Belvin, Harry L.; Allmen, John; Otero, Angel

2005-01-01

Contributions provided by the NASA Research Centers to key Space Shuttle return-to-flight milestones, with an emphasis on debris and Thermal Protection System (TPS) damage characterization, are described herein. Several CAIB recommendations and Space Shuttle Program directives deal with the mitigation of external tank foam insulation as a debris source, including material characterization as well as potential design changes, and an understanding of Orbiter TPS material characteristics, damage scenarios, and repair options. Ames, Glenn, and Langley Research Centers have performed analytic studies, conducted experimental testing, and developed new technologies, analysis tools, and hardware to contribute to each of these recommendations. For the External Tank (ET), these include studies of spray-on foam insulation (SOFI), investigations of potential design changes, and applications of advanced non-destructive evaluation (NDE) technologies to understand ET TPS shedding during liftoff and ascent. The end-to-end debris assessment included transport analysis to determine the probabilities of impact for various debris sources. For the Orbiter, methods were developed, and validated through experimental testing, to determine thresholds for potential damage of Orbiter TPS components. Analysis tools were developed and validated for on-orbit TPS damage assessments, especially in the area of aerothermal environments. Advanced NDE technologies were also applied to the Orbiter TPS components, including sensor technologies to detect wing leading edge impacts during liftoff and ascent. Work is continuing to develop certified TPS repair options and to develop improved methodologies for reinforced carbon-carbon (RCC) damage progression to assist in on-orbit repair decision philosophy.

Binary asteroid population. 2. Anisotropic distribution of orbit poles of small, inner main-belt binaries

NASA Astrophysics Data System (ADS)

Pravec, P.; Scheirich, P.; Vokrouhlický, D.; Harris, A. W.; Kušnirák, P.; Hornoch, K.; Pray, D. P.; Higgins, D.; Galád, A.; Világi, J.; Gajdoš, Š.; Kornoš, L.; Oey, J.; Husárik, M.; Cooney, W. R.; Gross, J.; Terrell, D.; Durkee, R.; Pollock, J.; Reichart, D. E.; Ivarsen, K.; Haislip, J.; LaCluyze, A.; Krugly, Yu. N.; Gaftonyuk, N.; Stephens, R. D.; Dyvig, R.; Reddy, V.; Chiorny, V.; Vaduvescu, O.; Longa-Peña, P.; Tudorica, A.; Warner, B. D.; Masi, G.; Brinsfield, J.; Gonçalves, R.; Brown, P.; Krzeminski, Z.; Gerashchenko, O.; Shevchenko, V.; Molotov, I.; Marchis, F.

2012-03-01

Our photometric observations of 18 main-belt binary systems in more than one apparition revealed a strikingly high number of 15 having positively re-observed mutual events in the return apparitions. Our simulations of the survey showed that it cannot be due to an observational selection effect and that the data strongly suggest that poles of mutual orbits between components of binary asteroids in the primary size range 3-8 km are not distributed randomly: The null hypothesis of an isotropic distribution of the orbit poles is rejected at a confidence level greater than 99.99%. Binary orbit poles concentrate at high ecliptic latitudes, within 30° of the poles of the ecliptic. We propose that the binary orbit poles oriented preferentially up/down-right are due to either of the two processes: (i) the YORP tilt of spin axes of their parent bodies toward the asymptotic states near obliquities 0° and 180° (pre-formation mechanism) or (ii) the YORP tilt of spin axes of the primary components of already formed binary systems toward the asymptotic states near obliquities 0° and 180° (post-formation mechanism). The alternative process of elimination of binaries with poles closer to the ecliptic by dynamical instability, such as the Kozai effect due to gravitational perturbations from the Sun, does not explain the observed orbit pole concentration. This is because for close binary asteroid systems, the gravitational effects of primary’s irregular shape dominate the solar-tide effect.

Long-term Stability of Tightly Packed Multi-planet Systems in Prograde, Coplanar, Circumstellar Orbits within the α Centauri AB System

NASA Astrophysics Data System (ADS)

Quarles, B.; Lissauer, Jack J.

2018-03-01

We perform long-term simulations, up to ten billion years, of closely spaced configurations of 2–6 planets, each as massive as the Earth, traveling on nested orbits about either stellar component in α Centauri AB. The innermost planet initially orbits at either the inner edge of its star’s empirical habitable zone (HZ) or the inner edge of its star’s conservative HZ. Although individual planets on low inclination, low eccentricity, orbits can survive throughout the HZs of both stars, perturbations from the companion star require that the minimum spacing of planets in multi-planet systems within the HZs of each star must be significantly larger than the spacing of similar multi-planet systems orbiting single stars in order to be long-lived. The binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star. Planets on appropriately phased circumstellar orbits with initial eccentricities equal to their forced eccentricities can survive on more closely spaced orbits than those with initially circular orbits, although the required spacing remains higher than for planets orbiting single stars. A total of up to nine planets on nested prograde orbits can survive for the current age of the system within the empirical HZs of the two stars, with five of these orbiting α Centauri B and four orbiting α Centauri A.

Comprehensive Evaluation of Attitude and Orbit Estimation Using Actual Earth Magnetic Field Data

NASA Technical Reports Server (NTRS)

Deutschmann, Julie K.; Bar-Itzhack, Itzhack Y.

2000-01-01

A single, augmented Extended Kalman Filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit has been developed and successfully tested with real magnetometer and gyro data only. Because the earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude; an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center (GSFC) Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only.

Orbital Engineering in Symmetry-Breaking Polar Heterostructures

NASA Astrophysics Data System (ADS)

Disa, Ankit S.; Kumah, Divine P.; Malashevich, Andrei; Chen, Hanghui; Arena, Dario A.; Specht, Eliot D.; Ismail-Beigi, Sohrab; Walker, F. J.; Ahn, Charles H.

2015-01-01

We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO3-LaNiO3-LaAlO3 system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ˜50 % change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO3 and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.

Results of an aerodynamic investigation of a space shuttle orbiter/747 carrier vehicle configuration to establish a free-stream data base for ALT separation investigations, utilizing a 0.0125-scale model (48-0/AX1318I-1) in the ARC 14-foot wind tunnel (CA23A)

NASA Technical Reports Server (NTRS)

Gillins, R. L.

1975-01-01

Force and moment data are presented which were obtained for each vehicle separately at a Mach number of 0.6, and for the mated orbiter/747 configuration at Mach numbers of 0.3, 0.5, 0.6, and 0.7. Orbiter angles of attack from 0 degrees to +12 degrees and 747/Carrier angles of attack from -3 degrees to +7 degrees were investigated at angles of sideslip of 0 degrees and -5 degrees. Model variables include orbiter elevon and rudder deflections, orbiter tail cone-on and off, various orbiter/747 attach structure configurations, 747 stabilizer and rudder deflections, and 747 CAM modification components-on and off. Photographs of test configurations are included.

Space augmentation of military high-level waste disposal

NASA Technical Reports Server (NTRS)

English, T.; Lees, L.; Divita, E.

1979-01-01

Space disposal of selected components of military high-level waste (HLW) is considered. This disposal option offers the promise of eliminating the long-lived radionuclides in military HLW from the earth. A space mission which meets the dual requirements of long-term orbital stability and a maximum of one space shuttle launch per week over a period of 20-40 years, is a heliocentric orbit about halfway between the orbits of earth and Venus. Space disposal of high-level radioactive waste is characterized by long-term predictability and short-term uncertainties which must be reduced to acceptably low levels. For example, failure of either the Orbit Transfer Vehicle after leaving low earth orbit, or the storable propellant stage failure at perihelion would leave the nuclear waste package in an unplanned and potentially unstable orbit. Since potential earth reencounter and subsequent burn-up in the earth's atmosphere is unacceptable, a deep space rendezvous, docking, and retrieval capability must be developed.

Long-Term Stability of Planets in the Alpha Centauri System

NASA Technical Reports Server (NTRS)

Lissauer, Jack; Quarles, Billy

2015-01-01

The alpha Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales, and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits of a single planet, which are larger for retrograde orbits relative to the binary than for pro-grade orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Overall, orbits of a single planet in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived. However, even well within regions where single planets are stable, multiple planet systems must be significantly more widely-spaced than they need to be around an isolated star in order to be long-lived.

Results of an external tank separation test in AEDC/VKF tunnel B on 0.010-scale replica of space shuttle vehicle model 52-OT(IA17A), Volume 1

NASA Technical Reports Server (NTRS)

Spangler, R. H.; Daileda, J. J.

1975-01-01

Tests were conducted on scale models of the space shuttle orbiter and external tank (ET) to determine the aerodynamic interactions during a return to launch site abort separation. The orbiter model was built to vehicle 3 configuration lines (139B) and the ET model approximated the vehicle 5 configurations with protuberances and attach hardware. For these investigations the orbiter was mounted on the primary support system and the external tank was mounted on the captive trajectory system. Six-component data were obtained for each vehicle at various orbiter angles of attack and sideslip for a range of relative angular and linear displacements of the ET from the orbiter.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

2017-09-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal-metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces.

PubMed

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M D

2017-09-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

PubMed Central

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

2017-01-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism. PMID:29333523

NASA Orbit Transfer Rocket Engine Technology Program

NASA Technical Reports Server (NTRS)

1984-01-01

The advanced expander cycle engine with a 15,000 lb thrust level and a 6:1 mixture ratio and optimized performance was used as the baseline for a design study of the hydrogen/oxgyen propulsion system for the orbit transfer vehicle. The critical components of this engine are the thrust chamber, the turbomachinery, the extendible nozzle system, and the engine throttling system. Turbomachinery technology is examined for gears, bearing, seals, and rapid solidification rate turbopump shafts. Continuous throttling concepts are discussed. Components of the OTV engine described include the thrust chamber/nozzle assembly design, nozzles, the hydrogen regenerator, the gaseous oxygen heat exchanger, turbopumps, and the engine control valves.

Validation of International Space Station Electrical Performance Model via On-orbit Telemetry

NASA Technical Reports Server (NTRS)

Jannette, Anthony G.; Hojnicki, Jeffrey S.; McKissock, David B.; Fincannon, James; Kerslake, Thomas W.; Rodriguez, Carlos D.

2002-01-01

The first U.S. power module on International Space Station (ISS) was activated in December 2000. Comprised of solar arrays, nickel-hydrogen (NiH2) batteries, and a direct current power management and distribution (PMAD) system, the electric power system (EPS) supplies power to housekeeping and user electrical loads. Modeling EPS performance is needed for several reasons, but primarily to assess near-term planned and off-nominal operations and because the EPS configuration changes over the life of the ISS. The System Power Analysis for Capability Evaluation (SPACE) computer code is used to assess the ISS EPS performance. This paper describes the process of validating the SPACE EPS model via ISS on-orbit telemetry. To accomplish this goal, telemetry was first used to correct assumptions and component models in SPACE. Then on-orbit data was directly input to SPACE to facilitate comparing model predictions to telemetry. It will be shown that SPACE accurately predicts on-orbit component and system performance. For example, battery state-of-charge was predicted to within 0.6 percentage points over a 0 to 100 percent scale and solar array current was predicted to within a root mean square (RMS) error of 5.1 Amps out of a typical maximum of 220 Amps. First, SPACE model predictions are compared to telemetry for the ISS EPS components: solar arrays, NiH2 batteries, and the PMAD system. Second, SPACE predictions for the overall performance of the ISS EPS are compared to telemetry and again demonstrate model accuracy.

Lessons from the Auriga discs: the hunt for the Milky Way's ex situ disc is not yet over

NASA Astrophysics Data System (ADS)

Gómez, Facundo A.; Grand, Robert J. J.; Monachesi, Antonela; White, Simon D. M.; Bustamante, Sebastian; Marinacci, Federico; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker; Frenk, Carlos S.

2017-12-01

We characterize the contribution from accreted material to the galactic discs of the Auriga Project, a set of high-resolution magnetohydrodynamic cosmological simulations of late-type galaxies performed with the moving-mesh code AREPO. Our goal is to explore whether a significant accreted (or ex situ) stellar component in the Milky Way disc could be hidden within the near-circular orbit population, which is strongly dominated by stars born in situ. One-third of our models shows a significant ex situ disc but this fraction would be larger if constraints on orbital circularity were relaxed. Most of the ex situ material (≳50 per cent) comes from single massive satellites (>6 × 1010 M⊙). These satellites are accreted with a wide range of infall times and inclination angles (up to 85°). Ex situ discs are thicker, older and more metal poor than their in situ counterparts. They show a flat median age profile, which differs from the negative gradient observed in the in situ component. As a result, the likelihood of identifying an ex situ disc in samples of old stars on near-circular orbits increases towards the outskirts of the disc. We show three examples that, in addition to ex situ discs, have a strongly rotating dark matter component. Interestingly, two of these ex situ stellar discs show an orbital circularity distribution that is consistent with that of the in situ disc. Thus, they would not be detected in typical kinematic studies.

Lunar-based Ultraviolet Telescope study of the well-known Algol-type binary TW Dra

NASA Astrophysics Data System (ADS)

Liao, Wen-Ping; Qian, Sheng-Bang; Zejda, Miloslav; Zhu, Li-Ying; Li, Lin-Jia

2016-06-01

By using the Lunar-based Ultraviolet Telescope (LUT) from 2014 December 2 to December 4, the first near-UV light curve of the well-known Algol-type binary TW Dra is reported, which is analyzed with the 2013 version of the W-D code. Our solutions confirmed that TW Dra is a semi-detached binary system where the secondary component fills its Roche lobe. The mass ratio and a high inclination are obtained (q = 0.47, i = 86.68°). Based on 589 available data spanning more than one century, the complex period changes are studied. Secular increase and three cyclical changes are found in the corresponding orbital period analysis. The secular increase changes reveal mass transfer from the secondary component to the primary one at a rate of 6.8 × 10-7 M ⊙ yr-1. One large cyclical change of 116.04 yr may be caused by disturbance of visual component ADS 9706B orbiting TW Dra (ADS 9706A), while the other two cyclical changes with shorter periods of 22.47 and 37.27 yr can be explained as the result of two circumbinary companions that are orbiting around TW Dra, where the two companions are in simple 3 : 5 orbit-rotation resonances. TW Dra itself is a basic binary in a possible sextuple system with the configuration (1 + 1) + (1 + 1) + (1 + 1), which further suggests that multiplicity may be a fairly common phenomenon in close binary systems.

The Splitting of Double-component Active Asteroid P/2016 J1 (PANSTARRS)

NASA Astrophysics Data System (ADS)

Moreno, F.; Pozuelos, F. J.; Novaković, B.; Licandro, J.; Cabrera-Lavers, A.; Bolin, Bryce; Jedicke, Robert; Gladman, Brett J.; Bannister, Michele T.; Gwyn, Stephen D. J.; Vereš, Peter; Chambers, Kenneth; Chastel, Serge; Denneau, Larry; Flewelling, Heather; Huber, Mark; Schunová-Lilly, Eva; Magnier, Eugene; Wainscoat, Richard; Waters, Christopher; Weryk, Robert; Farnocchia, Davide; Micheli, Marco

2017-03-01

We present deep imaging observations, orbital dynamics, and dust-tail model analyses of the double-component asteroid P/2016 J1 (J1-A and J1-B). The observations were acquired at the Gran Telescopio Canarias (GTC) and the Canada-France-Hawaii Telescope (CFHT) from mid-March to late July of 2016. A statistical analysis of backward-in-time integrations of the orbits of a large sample of clone objects of P/2016 J1-A and J1-B shows that the minimum separation between them occurred most likely ˜2300 days prior to the current perihelion passage, I.e., during the previous orbit near perihelion. This closest approach was probably linked to a fragmentation event of their parent body. Monte Carlo dust-tail models show that those two components became active simultaneously ˜250 days before the current perihelion, with comparable maximum loss rates of ˜0.7 and ˜0.5 kg s-1, and total ejected masses of 8 × 106 and 6 × 106 kg for fragments J1-A and J1-B, respectively. Consequently, the fragmentation event and the present dust activity are unrelated. The simultaneous activation times of the two components and the fact that the activity lasted 6-9 months or longer, strongly indicate ice sublimation as the most likely mechanism involved in the dust emission process.

Analysis of the optical emission of the young precataclysmic variables HS 1857+5144 and ABELL 65

NASA Astrophysics Data System (ADS)

Shimansky, V. V.; Pozdnyakova, S. A.; Borisov, N. V.; Bikmaev, I. F.; Vlasyuk, V. V.; Spiridonova, O. I.; Galeev, A. I.; Mel'Nikov, S. S.

2009-10-01

We analyze the physical state and the properties of the close binary systems HS 1857+5144 and Abell 65. We took the spectra of both systems over a wide range of orbital phases with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) and obtained their multicolor light curves with the RTT150 and Zeiss-1000 telescopes of the SAO RAS. We demonstrate that both Abell 65 and HS 1857+5144 are young precataclysmic variables (PV) with orbital periods of P orb = 1. d 003729 and P orb = 0. d 26633331, respectively. The observed brightness and spectral variations during the orbital period are due to the radiation of the cold component, which absorbs the short-wave radiation of the hot component and reemits it in the visual part of the spectrum. A joint analysis of the brightness and radial velocity curves allowed us to find the possible and optimum sets of their fundamental parameters. We found the luminosity excesses of the secondary components of HS 1857+5144 and Abell 65 with respect to the corresponding Main Sequence stars to be typical for such objects. The excess luminosities of the secondary components of all young PVs are indicative of their faster relaxation rate towards the quiescent state compared to the rates estimated in earlier studies.

Transiting exoplanets from the CoRoT space mission . VI. CoRoT-Exo-3b: the first secure inhabitant of the brown-dwarf desert

NASA Astrophysics Data System (ADS)

Deleuil, M.; Deeg, H. J.; Alonso, R.; Bouchy, F.; Rouan, D.; Auvergne, M.; Baglin, A.; Aigrain, S.; Almenara, J. M.; Barbieri, M.; Barge, P.; Bruntt, H.; Bordé, P.; Collier Cameron, A.; Csizmadia, Sz.; de La Reza, R.; Dvorak, R.; Erikson, A.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Guenther, E.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Lammer, H.; Léger, A.; Llebaria, A.; Loeillet, B.; Mayor, M.; Mazeh, T.; Moutou, C.; Ollivier, M.; Pätzold, M.; Pont, F.; Queloz, D.; Rauer, H.; Schneider, J.; Shporer, A.; Wuchterl, G.; Zucker, S.

2008-12-01

Context: The CoRoT space mission routinely provides high-precision photometric measurements of thousands of stars that have been continuously observed for months. Aims: The discovery and characterization of the first very massive transiting planetary companion with a short orbital period is reported. Methods: A series of 34 transits was detected in the CoRoT light curve of an F3V star, observed from May to October 2007 for 152 days. The radius was accurately determined and the mass derived for this new transiting, thanks to the combined analysis of the light curve and complementary ground-based observations: high-precision radial-velocity measurements, on-off photometry, and high signal-to-noise spectroscopic observations. Results: CoRoT-Exo-3b has a radius of 1.01 ± 0.07 R_Jup and transits around its F3-type primary every 4.26 days in a synchronous orbit. Its mass of 21.66 ± 1.0 M_Jup, density of 26.4 ± 5.6 g cm-3, and surface gravity of logg = 4.72 clearly distinguish it from the regular close-in planet population, making it the most intriguing transiting substellar object discovered so far. Conclusions: With the current data, the nature of CoRoT-Exo-3b is ambiguous, as it could either be a low-mass brown-dwarf or a member of a new class of “superplanets”. Its discovery may help constrain the evolution of close-in planets and brown-dwarfs better. Finally, CoRoT-Exo-3b confirms the trend that massive transiting giant planets (M ≥ 4 M_Jup) are found preferentially around more massive stars than the Sun. The CoRoT space mission, launched on December 27th 2006, has been developed and is operating by CNES, with the contribution of Austria, Belgium, Brasil, ESA, Germany and Spain. The first CoRoT data will be available to the public in February 2009 from the CoRoT archive: http://idoc-corot.ias.u-psud.fr/ Table of the COROT photometry is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/491/889

Precision GPS orbit determination strategies for an earth orbiter and geodetic tracking system

NASA Technical Reports Server (NTRS)

Lichten, Stephen M.; Bertiger, Willy I.; Border, James S.

1988-01-01

Data from two 1985 GPS field tests were processed and precise GPS orbits were determined. With a combined carrier phase and pseudorange, the 1314-km repeatability improves substantially to 5 parts in 10 to the 9th (0.6 cm) in the north and 2 parts in 10 to the 8th (2-3 cm) in the other components. To achieve these levels of repeatability and accuracy, it is necessary to fine-tune the GPS solar radiation coefficients and ground station zenith tropospheric delays.

Internuclear cascade-evaporation model for LET spectra of 200 MeV protons used for parts testing.

PubMed

O'Neill, P M; Badhwar, G D; Culpepper, W X

1998-12-01

The Linear Energy Transfer (LET) spectrum produced in microelectronic components during testing with 200 MeV protons is calculated with an intemuclear cascade-evaporation code. This spectrum is compared to the natural space heavy ion environment for various earth orbits. This comparison is used to evaluate the results of proton testing in terms of determining a firm upper bound to the on-orbit heavy ion upset rate and the risk of on-orbit heavy ion failures that would not be detected with protons.

Thermodynamic energy balance equations for Space Shuttle Orbiter gas compartment during ascent and re-entry

NASA Technical Reports Server (NTRS)

Ting, P. C.

1982-01-01

Thermodynamic energy balance equations are derived and applied to midsection Orbiter-payload atmospheric thermal math models (TMMs) to predict Orbiter component, element, compartment, internal insolation and structure temperatures in support of NASA/JSC mission planning, postflight thermal analysis and payload thermal integration planning. The equations are extended and applied to the forward section, midsection, and aft section of the TMMs for five Orbiter mission phases: prelaunch on pad with purge, lift-off to ascent, re-entry to touchdown, post landing without purge, and post-landing with purge. Predicted results from the 390 node/DFI atmospheric TMM are in good agreement with STS-1 flight measurement data.

Orbiter integrated active thermal control subsystem test

NASA Technical Reports Server (NTRS)

Jaax, J. R.

1980-01-01

Integrated subsystem level testing of the systems within the orbiter active thermal chamber capable of simulating ground, orbital, and entry temperature and pressure profiles. The test article was in a closed loop configuration that included flight type and functionally simulated protions of all ATCS components for collecting, transporting, and rejecting orbiter waste heat. Specially designed independently operating equipment simulated the transient thermal input from the cabin, payload, fuel cells, freon cold plates, hydraulic system, and space environment. Test team members using data, controls, and procedures available to a flight crew controlled the operation of the ATCS. The ATCS performance met or exceeded all thermal and operational requirements for planned and contingency mission support.

Resolved Observations of the Patroclus-Menoetius Binary

NASA Astrophysics Data System (ADS)

Noll, Keith S.; Grundy, William M.; Buie, Marc W.; Levison, Harold F.

2017-10-01

The Trojan binary (617) Patroclus-Menoetius is one of the targets of the Lucy Discovery mission. Lucy is scheduled to launch in October 2021. We observed this system with the Hubble Space Telescope in May and June 2017 in order to resolve the individual components and use the relative positions to update the binary orbit. The updated orbit is required to predict the upcoming mutual event season. A precise determination of the orbit phase, period, orbit plane and pole position that will result from observations of mutual events is essential for planning the Lucy mission’s encounter with this system. We present results of the successful HST observations including preliminary predictions for mutual events observable in semester 2018A.

Independent Orbiter Assessment (IOA): Analysis of the orbital maneuvering system

NASA Technical Reports Server (NTRS)

Prust, C. D.; Paul, D. J.; Burkemper, V. J.

1987-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbital Maneuvering System (OMS) hardware are documented. The OMS provides the thrust to perform orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS is housed in two independent pods located one on each side of the tail and consists of the following subsystems: Helium Pressurization; Propellant Storage and Distribution; Orbital Maneuvering Engine; and Electrical Power Distribution and Control. The IOA analysis process utilized available OMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluted and analyzed for possible failure modes and effects. Criticality was asigned based upon the severity of the effect for each failure mode.

Exploring the fission and reconfiguration cycle of comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Scheeres, Daniel J.; Hirabayashi, Masatoshi; Chesley, Steven R.; McMahon, Jay W.

2016-10-01

In Hirabayashi et al. (Nature, 2016) the nucleus of comet 67P/Churyumov-Gerasimenko (67P) is studied with a focus on the straight cracks observed on the Hapi region. These cracks were shown to have formed during a period of fast rotation and led to a proposed evolutionary scenario in which the nuclei may eventually split into two components and recombine to create a new bilobate configuration. Other bilobate nuclei should be subject to such a reconfiguration process, based on the relative sizes of the components, suggesting that this evolutionary scenario may be common for bilobate nuclei which comprise the majority of comet nuclei observed at high spatial resolution. Such reconfigurations could explain the observed occurrence of comet nucleus splitting and brightening events, which still lack a definitive geophysical understanding. Motivated by the proposed theory in Hirabayashi et al., the current work explores the dynamics of the 67P nucleus' rotation rate, fission limits, and subsequent dynamics. One aspect of the theory posits that the comet's distant Jupiter flybys will cause the latitude of the sub-solar point at perihelion to vary chaotically, leading to periods of net positive and negative torques and causing the nucleus to spin-up and spin-down in a random fashion. We analyze the current 67P nucleus shape and orbit to estimate the characteristic time-scale of this rotational evolution, providing an estimate of the current nucleus lifetime in its current configuration. Once the nucleus reaches a spin period shorter than ~7 hours the components will fission into a bound orbit, with the components subsequently reimpacting at speeds less than local escape speed (about 0.4 m/s). The current study extends Hirabayashi et al., explicitly modeling the mutual gravity and orbital dynamics of the head and body, assuming that the head and body rest on each other with the current shape of the 67P nucleus. The results show that when the components are released at a spin period between 6.5 hr and 7 hr, the components will separate and subsequently collide with a low impact speed. The orbital and rotational dynamics of the system components after fission are explored as a function of the initial spin rate at fission.

Precise Tracking of the Magellan and Pioneer Venus Orbiters by Same-Beam Interferometry. Part 2: Orbit Determination Analysis

NASA Technical Reports Server (NTRS)

Folkner, W. M.; Border, J. S.; Nandi, S.; Zukor, K. S.

1993-01-01

A new radio metric positioning technique has demonstrated improved orbit determination accuracy for the Magellan and Pioneer Venus Orbiter orbiters. The new technique, known as Same-Beam Interferometry (SBI), is applicable to the positioning of multiple planetary rovers, landers, and orbiters which may simultaneously be observed in the same beamwidth of Earth-based radio antennas. Measurements of carrier phase are differenced between spacecraft and between receiving stations to determine the plane-of-sky components of the separation vector(s) between the spacecraft. The SBI measurements complement the information contained in line-of-sight Doppler measurements, leading to improved orbit determination accuracy. Orbit determination solutions have been obtained for a number of 48-hour data arcs using combinations of Doppler, differenced-Doppler, and SBI data acquired in the spring of 1991. Orbit determination accuracy is assessed by comparing orbit solutions from adjacent data arcs. The orbit solution differences are shown to agree with expected orbit determination uncertainties. The results from this demonstration show that the orbit determination accuracy for Magellan obtained by using Doppler plus SBI data is better than the accuracy achieved using Doppler plus differenced-Doppler by a factor of four and better than the accuracy achieved using only Doppler by a factor of eighteen. The orbit determination accuracy for Pioneer Venus Orbiter using Doppler plus SBI data is better than the accuracy using only Doppler data by 30 percent.

QUENCHING OF CARBON MONOXIDE AND METHANE IN THE ATMOSPHERES OF COOL BROWN DWARFS AND HOT JUPITERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visscher, Channon; Moses, Julianne I., E-mail: visscher@lpi.usra.edu, E-mail: jmoses@spacescience.org

We explore CO{r_reversible}CH{sub 4} quench kinetics in the atmospheres of substellar objects using updated timescale arguments, as suggested by a thermochemical kinetics and diffusion model that transitions from the thermochemical-equilibrium regime in the deep atmosphere to a quench-chemical regime at higher altitudes. More specifically, we examine CO quench chemistry on the T dwarf Gliese 229B and CH{sub 4} quench chemistry on the hot-Jupiter HD 189733b. We describe a method for correctly calculating reverse rate coefficients for chemical reactions, discuss the predominant pathways for CO{r_reversible}CH{sub 4} interconversion as indicated by the model, and demonstrate that a simple timescale approach can bemore » used to accurately describe the behavior of quenched species when updated reaction kinetics and mixing-length-scale assumptions are used. Proper treatment of quench kinetics has important implications for estimates of molecular abundances and/or vertical mixing rates in the atmospheres of substellar objects. Our model results indicate significantly higher K{sub zz} values than previously estimated near the CO quench level on Gliese 229B, whereas current-model-data comparisons using CH{sub 4} permit a wide range of K{sub zz} values on HD 189733b. We also use updated reaction kinetics to revise previous estimates of the Jovian water abundance, based upon the observed abundance and chemical behavior of carbon monoxide. The CO chemical/observational constraint, along with Galileo entry probe data, suggests a water abundance of approximately 0.51-2.6 x solar (for a solar value of H{sub 2}O/H{sub 2} = 9.61 x 10{sup -4}) in Jupiter's troposphere, assuming vertical mixing from the deep atmosphere is the only source of tropospheric CO.« less

The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene A.; Aller, Kimberly M.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

2018-05-01

We are conducting a proper-motion survey for young brown dwarfs in the Taurus-Auriga molecular cloud based on the Pan-STARRS1 3π Survey. Our search uses multi-band photometry and astrometry to select candidates, and is wider (370 deg2) and deeper (down to ≈3 M Jup) than previous searches. We present here our search methods and spectroscopic follow-up of our high-priority candidates. Since extinction complicates spectral classification, we have developed a new approach using low-resolution (R ≈ 100) near-infrared spectra to quantify reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≲100–3 M Jup in Taurus). We have discovered 25 low-gravity (VL-G) and the first 11 intermediate-gravity (INT-G) substellar (M6–L1) members of Taurus, constituting the largest single increase of Taurus brown dwarfs to date. We have also discovered 1 new Pleiades member and 13 new members of the Perseus OB2 association, including a candidate very wide separation (58 kau) binary. We homogeneously reclassify the spectral types and extinctions of all previously known Taurus brown dwarfs. Altogether our discoveries have thus far increased the substellar census in Taurus by ≈40% and added three more L-type members (≲5–10 M Jup). Most notably, our discoveries reveal an older (>10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. The mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes.

Usefulness of the anterolateral thigh flap with vascularized fascia lata for reconstruction of orbital floor and nasal surface after total maxillectomy.

PubMed

Joo, Young-Hoon; Cho, Kwang-Jae; Park, Jun-Ook; Kim, Min-Sik

2013-09-01

The aim of this study was to describe a technique using the fascia lata (FL) component of the anterolateral thigh (ALT) flap to re-create the orbital floor and lateral nasal wall after total maxillectomy. Retrospective analysis of medical records. A total of 22 patients underwent maxillary reconstruction using a composite ALT-FL flap following cancer resection. All patients underwent total maxillectomies via the Weber-Ferguson approach. The ALT flap was harvested with the deep fascia of the thigh with the aim of using it for lining of the orbital floor and lateral nasal cavity. The FL was sutured to the palatine bone inferiorly, nasal bone and zygomatic bone superiorly, and nasopharyngeal mucosa posteriorly to provide an orbital floor and make a neonasal cavity. There was 100% free flap survival. Speech was normal in eight (36%) patients, near normal in 10 (46%), and intelligible in four (18%). Seventeen (77%) patients gained a good facial appearance, and five (23%) a fair appearance. Sixteen (73%) patients complained of mild nasal crust formation, and the rest (27%) developed moderate crust. Microvascular reconstruction using a composite ALT-FL flap provided a reliable fascial component for orbital floor and nasal surface reconstruction of total maxillectomy defects. Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Observations of TOPEX/Poseidon Orbit Errors Due to Gravitational and Tidal Modeling Errors Using the Global Positioning System

NASA Technical Reports Server (NTRS)

Haines, B.; Christensen, E.; Guinn, J.; Norman, R.; Marshall, J.

1995-01-01

Satellite altimetry must measure variations in ocean topography with cm-level accuracy. The TOPEX/Poseidon mission is designed to do this by measuring the radial component of the orbit with an accuracy of 13 cm or better RMS. Recent advances, however, have improved this accuracy by about an order of magnitude.

A Hamiltonian approach to the planar optimization of mid-course corrections

NASA Astrophysics Data System (ADS)

Iorfida, E.; Palmer, P. L.; Roberts, M.

2016-04-01

Lawden's primer vector theory gives a set of necessary conditions that characterize the optimality of a transfer orbit, defined accordingly to the possibility of adding mid-course corrections. In this paper a novel approach is proposed where, through a polar coordinates transformation, the primer vector components decouple. Furthermore, the case when transfer, departure and arrival orbits are coplanar is analyzed using a Hamiltonian approach. This procedure leads to approximate analytic solutions for the in-plane components of the primer vector. Moreover, the solution for the circular transfer case is proven to be the Hill's solution. The novel procedure reduces the mathematical and computational complexity of the original case study. It is shown that the primer vector is independent of the semi-major axis of the transfer orbit. The case with a fixed transfer trajectory and variable initial and final thrust impulses is studied. The acquired related optimality maps are presented and analyzed and they express the likelihood of a set of trajectories to be optimal. Furthermore, it is presented which kind of requirements have to be fulfilled by a set of departure and arrival orbits to have the same profile of primer vector.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, an orbital maneuvering system (OMS) pod is moved into place on Atlantis. It is one of two OMS pods attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts.

NASA Image and Video Library

2003-10-30

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, an orbital maneuvering system (OMS) pod is moved into place on Atlantis. It is one of two OMS pods attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, an orbital maneuvering system (OMS) pod is suspended in air as it is moved toward Atlantis for installation. Two OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts.

NASA Image and Video Library

2003-10-30

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, an orbital maneuvering system (OMS) pod is suspended in air as it is moved toward Atlantis for installation. Two OMS pods are attached to the upper aft fuselage left and right sides. Fabricated primarily of graphite epoxy composite and aluminum, each pod is 21.8 feet long and 11.37 feet wide at its aft end and 8.41 feet wide at its forward end, with a surface area of approximately 435 square feet. Each pod houses the Reaction Control System propulsion components used for inflight maneuvering and is attached to the aft fuselage with 11 bolts.