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Sample records for detecting circumbinary planets

  1. Dynamical Detection of Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Clark Fabrycky, Daniel; Orosz, Jerome; Welsh, William

    2015-12-01

    The Kepler data revealed a population of transiting gas-giant planets orbiting around close binary stars, beginning with Kepler-16, a highlight of the Extreme Solar Systems II meeting. Due to the restrictive geometry requirements of transit detections, this population is highly observationally biased towards coplanarity. However, a third of those planets detectably perturb their host binary's eclipse times, such that they could have been recognized even without transits. Here we announce the detection of three non-transiting planets based on this dynamical technique. Apsidal precession due to the planet makes the primary and secondary eclipse periods differ, and in addition a short-term modulation of the binary's eclipse times reveals the planet's orbital period. Several planetary periods are observed for each system, buttressing the interpretation. Though the method is nearly equally sensitive to all orbital orientations, each planet orbits near its host binary's plane, suggesting this class of planets formed in the circumbinary nebula.

  2. Prospects on the detection of additional circumbinary extrasolar planets

    NASA Astrophysics Data System (ADS)

    Hinse, T. C.; Haghighipour, N.; Gozdziewski, K.; Lee, J. W.; Lee, C.-U.

    2012-09-01

    The presence of additional bodies orbiting a binary star system can be detected by monitoring the binary's mid-eclipse timing. These so-called circumbinary objects will reveal themselves by i) either introducing a reflex motion of the binary system about the total system's barycenter creating a light-travel time effect (LITE), ii) by gravitational perturbations on the binary orbit, or iii) a combination of the two effects resulting in eclipse timing variations (ETVs). Motivated by the three recently detected circumbinary planets by the Kepler space telescope (Kepler- 16b, Kepler-34b, Kepler-35b), we have launched a large project aiming to study the detectability of nontransiting and inclined circumbinary planets using the ETV technique. We have used MEGNO to quantitativelymap the chaotic/quasi-periodic regions of the orbital parameter-space and to determine where the orbit of a circumbinary planet will be stable. We have calculated the amplitudes of ETV signals for different values of the mass and orbital elements of the planet and binary. Special attention has been given to several high-order mean-motion resonances (MMRs). While we have been able to verify the orbital configurations of the currently known transiting circumbinary planets, we have determined the ranges of the planet's orbital elements and mass for which the resulted ETV will be within the limits of the sensitivity of ground- and space-based telescope. We will present our results and discussed their implications for detecting such bodies with CoRoT and Kepler.

  3. Caustic Structures and Detectability of Circumbinary Planets in Microlensing

    NASA Astrophysics Data System (ADS)

    Luhn, Jacob K.; Penny, Matthew T.; Gaudi, B. Scott

    2016-08-01

    Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main-sequence stars. Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events. We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space. Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host. We have used this expression to show that the dominant source of caustic motion will be due to the planet’s orbital motion and not that of the binary star. Finally, we estimate the fraction of circumbinary microlensing events that are recognizable as such to be significant (5%–50%) for binary projected separations in the range 0.1–0.5 in units of Einstein radii.

  4. A New Method for Detecting Transiting Circumbinary Planets in Kepler Data

    NASA Astrophysics Data System (ADS)

    Welsh, William F.; Orosz, Jerome A.; Windmiller, Gur; Short, Donald R.

    2016-06-01

    The discovery of Kepler-16 started a new branch of exoplanet research: observations of transiting circumbinary planets. To date, eleven transiting circumbinary planets have been discovered. The detection of a circumbinary planet is much more difficult than the detection of a planet around a single star because the transit times are not strictly periodic, the transit widths and depths can change dramatically, and the deep binary star eclipses overwhelm the much smaller planetary transits. Because of these complications, most of the known circumbinary planets were discovered via visual inspection of the Kepler light curves. This requires that the transits be easily detectable by eye, which translates to large-radii planets. Here we present a new method for visual dectection of circumbinary planets, based on the idea of phase-folding the light curve into a "trailed eclipsogram" image. While this method works well for deep transits (and hence will work for new, large circumbinary planets to be found by TESS), in principle it can also be extended to much smaller planets below the threshold for visual detection using image pattern recognition tools.

  5. Aspects on the Dynamics and Detection of Additional Circumbinary Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Hinse, Tobias C.; Haghighipour, Nader; Goździewski, Krzysztof

    2014-04-01

    The presence of additional bodies orbiting a binary star system can be detected by monitoring the binary's eclipse timing. These so-called circumbinary objects will reveal themselves by i) either introducing a reflex motion of the binary system about the total system's barycenter creating a geometric light-travel time effect (LITE), ii) by gravitational perturbations on the binary orbit, or iii) a combination of the two effects resulting in eclipse timing (ETV) and transit timing (TTV) variations. Motivated by the four recently detected circumbinary planets by the Kepler space telescope (Kepler-16b, Kepler-34b, Kepler-35b and Kepler-38b) we have begun to study their dynamics in the presence of an additional massive perturber. In particular we used Kepler-16b as a test bed case. We are aiming to study the detectability of non-transiting and inclined circumbinary planets using the ETV effect along with the fast indicator MEGNO to quantitatively map the chaotic/quasi-periodic regions of the orbital parameter-space and to determine where the orbit of a circumbinary planet will be stable. We have calculated the amplitudes of TTV and ETV signals for different values of the mass and orbital elements of the planet and binary.

  6. Detecting Circumbinary Planets Using Eclipse Timing of Binary Stars - From Simulations to Observations

    NASA Astrophysics Data System (ADS)

    Sybilski, Piotr; Konacki, M.; Kozlowski, S. K.

    2010-05-01

    The Light-Time Effect (LTE) occurs whenever the distance between the observer and any kind of periodic signal occurring in space changes. The usual cause of this is the reflex motion about the system's barycenter due to the gravitational influence of one or more additional bodies. With a sufficient precision of the times of eclipses, the eclipse timing can be used to detect substellar or even planetary mass companions. The main goal of the poster is to investigate the potential of the photometry based eclipse timing of binary stars as a method of detecting circumbinary planets. In the models we assume that the companion orbits a binary star in a circular Keplerian orbit. We analyze throug the numerical simulations both the space and ground based photometry cases. In particular, we study the usefulness of the on-going COROT and Kepler missions in detecting circumbinary planets. We determine the sensitivity of the eclipse timing technique to circumbinary planets for the ground and space based photometric observations. We provide suggestions for the best targets, observing strategies and instruments for the eclipse timing method. Finally, we present some preliminary results comparing simulations and real observations.

  7. Recent Kepler Results On Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Welsh, William F.; Orosz, Jerome A.; Carter, Joshua A.; Fabrycky, Daniel C.

    2014-04-01

    Ranked near the top of the long list of exciting discoveries made with NASA's Kepler photometer is the detection of transiting circumbinary planets. In just over a year the number of such planets went from zero to seven, including a multi-planet system with one of the planets in the habitable zone (Kepler-47). We are quickly learning to better detect and characterize these planets, including the recognition of their transit timing and duration variation ``smoking gun'' signature. Even with only a handful of such planets, some exciting trends are emerging.

  8. Improved Dynamical Parameters for Transiting Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Thomadis, Pantelis C.; Orosz, Jerome A.; Welsh, William F.; Friedmann, Matan; Mazeh, Tsevi; Short, Donald R.; Windmiller, Gur

    2016-06-01

    To date, the Kepler space telescope has detected about a dozen transiting circumbinary planets (i.e. planets that orbit a binary star system). Here we present improved dynamical parameters for the following four circumbinary planets: Kepler-16b (Doyle et al. 2011), 34b and 35b (Welsh et al. 2012), and 38b (Orosz et al. 2012). The original analyses contained only a subsample of the entire Kepler dataset available today. In the case of Kepler-16b, we have also obtained additional spectra and an additional transit not present in the Kepler photometry. We present updated parameters for these four systems, including a preliminary search for additional bodies in the Kepler-16 system.

  9. The Fate of Unstable Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    What happens to Tattooine-like planets that are instead in unstable orbits around their binary star system? A new study examines whether such planets will crash into a host star, get ejected from the system, or become captured into orbit around one of their hosts.Orbit Around a DuoAt this point we have unambiguously detected multiple circumbinary planets, raising questions about these planets formation and evolution. Current models suggest that it is unlikely that circumbinary planets would be able to form in the perturbed environment close their host stars. Instead, its thought that the planets formed at a distance and then migrated inwards.One danger such planets face when migrating is encountering ranges of radii where their orbits become unstable. Two scientists at the University of Chicago, Adam Sutherland and Daniel Fabrycky, have studied what happens when circumbinary planets migrate into such a region and develop unstable orbits.Producing Rogue PlanetsTime for planets to either be ejected or collide with one of the two stars, as a function of the planets starting distance (in AU) from the binary barycenter. Colors represent different planetary eccentricities. [Sutherland Fabrycky 2016]Sutherland and Fabrycky used N-body simulations to determine the fates of planets orbiting around a star system consisting of two stars a primary like our Sun and a secondary roughly a tenth of its size that are separated by 1 AU.The authors find that the most common fate for a circumbinary planet with an unstable orbit is ejection from the system; over 80% of unstable planets were ejected. This has interesting implications: if the formation of circumbinary planets is common, this mechanism could be filling the Milky Way with a population of free-floating, rogue planets that no longer are associated with their host star.The next most common outcome for unstable planets is collision with one of their host stars (most often the secondary), resulting inaccretion of the planet

  10. Formation and Dynamics of Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Lai, Dong

    2016-05-01

    The discovery of more than a dozen transiting circumbinary planets provides new constraints on the planet formation and migration processes in circumbinary disks and also raises a number of puzzles. I will discuss several recent works related to circumbinary planets and disks. (1) New long-duration hydro simulations of circumbinary disks (R.Miranda, D.Lai and D.Munoz 2016). The simulations reveal that the inner circumbinary disk may develop appreciable eccentricity and precesseses coherently -- these features are bound to have a strong impact on planet-disk interaction. (2) The disruption of planetary orbits through evection resonances with an external companion (W.Xu and D.Lai 2016a). This may help explain the lack of transiting planets around very compact stellar binaries (D.Munoz and D.Lai 2015). (3) The stability of mean-motion resonance capture as planets migrate inwards in a circumbinary disk. This relates to the pile-up of planets near the stability limit as observed in the sample of transiting circumbinary planets (W.Xu and D.Lai 2016b).

  11. Kepler-16: a transiting circumbinary planet.

    PubMed

    Doyle, Laurance R; Carter, Joshua A; Fabrycky, Daniel C; Slawson, Robert W; Howell, Steve B; Winn, Joshua N; Orosz, Jerome A; Prša, Andrej; Welsh, William F; Quinn, Samuel N; Latham, David; Torres, Guillermo; Buchhave, Lars A; Marcy, Geoffrey W; Fortney, Jonathan J; Shporer, Avi; Ford, Eric B; Lissauer, Jack J; Ragozzine, Darin; Rucker, Michael; Batalha, Natalie; Jenkins, Jon M; Borucki, William J; Koch, David; Middour, Christopher K; Hall, Jennifer R; McCauliff, Sean; Fanelli, Michael N; Quintana, Elisa V; Holman, Matthew J; Caldwell, Douglas A; Still, Martin; Stefanik, Robert P; Brown, Warren R; Esquerdo, Gilbert A; Tang, Sumin; Furesz, Gabor; Geary, John C; Berlind, Perry; Calkins, Michael L; Short, Donald R; Steffen, Jason H; Sasselov, Dimitar; Dunham, Edward W; Cochran, William D; Boss, Alan; Haas, Michael R; Buzasi, Derek; Fischer, Debra

    2011-09-16

    We report the detection of a planet whose orbit surrounds a pair of low-mass stars. Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints on the absolute dimensions of all three bodies. The planet is comparable to Saturn in mass and size and is on a nearly circular 229-day orbit around its two parent stars. The eclipsing stars are 20 and 69% as massive as the Sun and have an eccentric 41-day orbit. The motions of all three bodies are confined to within 0.5° of a single plane, suggesting that the planet formed within a circumbinary disk. PMID:21921192

  12. Stability of habitable exomoons of circumbinary planets

    NASA Astrophysics Data System (ADS)

    Satyal, Suman; Haghighipour, Nader; Quarles, Billy

    2015-12-01

    Among the currently known Kepler circumbinary planets, three, namely Kepler-453b, Kepler-16b, and Kepler-47c are in the binary habitable zone (HZ). Given the large sizes of these planets, it is unlikely that they would be habitable. However, similar to the giant planets in our solar system, these planets may have large moons, which orbit their host planets while in the HZ. These exomoons, if exist, present viable candidates for habitability. As a condition for habitability, the planet-moon system has to maintain its orbital stability for long time. Usually, the empirical formula by Holeman & Wiegert (1999) is used as a measure of orbital stability in circumbinary systems. However, this formula was obtained by assuming planets to be test particles and therefore does not include possible perturbation of the planet on the binary. In this work, we present results of more realistic calculations of stability of circumbinary planets where the interactions between planets and their central binaries are taken into account. We map the region of stability, which in this case will be specific to each system, and determine the range of the orbital parameters of the moons for which their orbits will be long-term stable.

  13. Kepler-47: A Three-Planet Circumbinary System

    NASA Astrophysics Data System (ADS)

    Welsh, William; Orosz, Jerome; Quarles, Billy; Haghighipour, Nader

    2015-12-01

    Kepler-47 is the most interesting of the known circumbinary planets. In the discovery paper by Orosz et al. (2012) two planets were detected, with periods of 49.5 and 303 days around the 7.5-day binary. In addition, a single "orphan" transit of a possible third planet was noticed. Since then, five additional transits by this planet candidate have been uncovered, leading to the unambiguous confirmation of a third transiting planet in the system. The planet has a period of 187 days, and orbits in between the previously detected planets. It lies on the inner edge of the optimistic habitable zone, while its outer sibling falls within the conservative habitable zone. The orbit of this new planet is precessing, causing its transits to become significantly deeper over the span of the Kepler observations. Although the planets are not massive enough to measurably perturb the binary, they are sufficiently massive to interact with each other and cause mild transit timing variations (TTVs). This enables our photodynamical model to estimate their masses. We find that all three planets have very low-density and are on remarkably co-planar orbits: all 4 orbits (the binary and three planets) are within ~2 degrees of one another. Thus the Kepler-47 system puts interesting constraints on circumbinary planet formation and migration scenarios.

  14. Examining Tatooine: Atmospheric Models of Neptune-like Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    May, E. M.; Rauscher, E.

    2016-08-01

    Circumbinary planets experience a time-varying irradiation pattern as they orbit their two host stars. In this work, we present the first detailed study of the atmospheric effects of this irradiation pattern on known and hypothetical gaseous circumbinary planets. Using both a one-dimensional energy balance model (EBM) and a three-dimensional general circulation model (GCM), we look at the temperature differences between circumbinary planets and their equivalent single-star cases in order to determine the nature of the atmospheres of these planets. We find that for circumbinary planets on stable orbits around their host stars, temperature differences are on average no more than 1.0% in the most extreme cases. Based on detailed modeling with the GCM, we find that these temperature differences are not large enough to excite circulation differences between the two cases. We conclude that gaseous circumbinary planets can be treated as their equivalent single-star case in future atmospheric modeling efforts.

  15. Searching for Circumprimary and Circumbinary Planets in Kepler Data

    NASA Astrophysics Data System (ADS)

    Haghighipour, Nader

    We propose to use the currently available data from the Kepler space telescope (specifically, variations in transit and eclipse timing) to detect planets in circumprimary and circumbinary orbits in binary star systems. The detection of planets in close binary stars during the past decade and the recent success of the Kepler space telescope in detecting planets in circumbinary orbits strongly suggest that planet formation in and around binary stars is robust and planets of variety of sizes may exist in dual-star systems. Given that approximately 60% of the main and pre-main sequence stars are in binaries, many of such planet-hosting dual-stars are expected to exist which naturally leads to several fundamental questions on the formation, characteristics, frequency, and habitability of their planets. However, the small number of the currently known planets in binary star systems (only 8) does not allow for arriving at statistically meaningful answers to these questions. The success of the Kepler space telescope in identifying more than 2300 planetary candidates (of which many may be in close dual-stars) and over 2100 eclipsing binaries has provided rich grounds for searching for planet-hosting binary stars and increasing the number of their planets. We propose to use the data from quarter 0 (Q0) to quarter 6 (Q6), to identify the signature(s) of planet(s) in and around binary stars by analyzing the variations in the times of planetary transit or the eclipses of the binary. We will use the transit timing variations of the +2300 planetary candidates for detecting stellar companions to their planet-hosting stars, and the eclipse timing variations of the +2100 binary star systems to detect circumbinary planets. We have developed a powerful algorithm dubbed as QATS that allows us to analyze eclipse and transit timing variations accurately and efficiently. To properly account for the frequency of planets in binary stars systems and comparing that with the frequency of

  16. PREDICTING A THIRD PLANET IN THE KEPLER-47 CIRCUMBINARY SYSTEM

    SciTech Connect

    Hinse, Tobias C.; Haghighipour, Nader; Kostov, Veselin B.; Goździewski, Krzysztof

    2015-01-20

    We have studied the possibility that a third circumbinary planet in the Kepler-47 planetary system is the source of the single unexplained transiting event reported during the discovery of these planets. We applied the MEGNO technique to identify regions in the phase space where a third planet can maintain quasi-periodic orbits, and assessed the long-term stability of the three-planet system by integrating the entire five bodies (binary + planets) for 10 Myr. We identified several stable regions between the two known planets as well as a region beyond the orbit of Kepler-47c where the orbit of the third planet could be stable. To constrain the orbit of this planet, we used the measured duration of the unexplained transit event (∼4.15 hr) and compared that with the transit duration of the third planet in an ensemble of stable orbits. To remove the degeneracy among the orbits with similar transit durations, we considered the planet to be in a circular orbit and calculated its period analytically. The latter places an upper limit of 424 days on the orbital period of the third planet. Our analysis suggests that if the unexplained transit event detected during the discovery of the Kepler-47 circumbinary system is due to a planetary object, this planet will be in a low eccentricity orbit with a semi-major axis smaller than 1.24 AU. Further constraining of the mass and orbital elements of this planet requires a re-analysis of the entire currently available data, including those obtained post-announcement of the discovery of this system. We present details of our methodology and discuss the implication of the results.

  17. Kozai-Lidov cycles towards the limit of circumbinary planets

    NASA Astrophysics Data System (ADS)

    Martin, David V.; Triaud, Amaury H. M. J.

    2016-01-01

    In this Letter, we answer a simple question: Can a misaligned circumbinary planet induce Kozai-Lidov cycles on an inner stellar binary? We use known analytic equations to analyse the behaviour of the Kozai-Lidov effect as the outer mass is made small. We demonstrate a significant departure from the traditional symmetry, critical angles and amplitude of the effect. Aside from massive planets on near-polar orbits, circumbinary planetary systems are devoid of Kozai-Lidov cycles. This has positive implications for the existence of highly misaligned circumbinary planets: an observationally unexplored and theoretically important parameter space.

  18. A transiting circumbinary planet in KIC 10753734

    NASA Astrophysics Data System (ADS)

    Orosz, Jerome A.; Welsh, William F.; Short, Donald R.; Endl, Michael; Cochran, William D.; Johnson, Marshall C.; Mills, Sean; Fabrycky, Daniel; Haghighipour, Nader; Windmiller, Gur

    2016-06-01

    KIC 10753734 is an eclipsing binary discovered by NASA's Kepler mission. The binary period is about 19.4 days with a moderately large eccentricity of e=0.52. Spectroscopic observations from McDonald Observatory show the system is double-lined, which allow us to derive masses for the primary and secondary stars, both of which are roughly solar-like. Two weak transit-like events separated by 6.5 days appear in the Kepler light curve near the end of the nominal mission. A careful examination of the light curve at earlier times reveals two weak transit events (separated by about 7 days) that occurred about 250 days earlier. We show that the two pairs of events represent transits of both stars at successive conjunctions of a circumbinary planet with a period of about 260 days and a radius of about 6 Earth radii. The lack of large eclipse timing variations limit the third body to be sub-stellar in mass, i.e. a planet. Despite the deep primary and secondary eclipses, the analysis is hampered by spots on both stars. We present a progress report on the modelling effort to date, and present preliminary characteristics of the planet.

  19. THE RADIAL VELOCITY TATOOINE SEARCH FOR CIRCUMBINARY PLANETS: PLANET DETECTION LIMITS FOR A SAMPLE OF DOUBLE-LINED BINARY STARS-INITIAL RESULTS FROM KECK I/HIRES, SHANE/CAT/HAMSPEC, AND TNG/SARG OBSERVATIONS

    SciTech Connect

    Konacki, Maciej; Helminiak, Krzysztof G.; Muterspaugh, Matthew W.; Kulkarni, Shrinivas R.

    2009-10-10

    We present preliminary results of the first and on-going radial velocity survey for circumbinary planets. With a novel radial velocity technique employing an iodine absorption cell, we achieve an unprecedented radial velocity (RV) precision of up to 2 m s{sup -1} for double-lined binary stars. The high-resolution spectra collected with the Keck I/Hires, TNG/Sarg, and Shane/CAT/Hamspec telescopes/spectrographs over the years 2003-2008 allow us to derive RVs and compute planet detection limits for 10 double-lined binary stars. For this initial sample of targets, we can rule out planets on dynamically stable orbits with masses as small as approx0.3 to 3 M {sub Jup} for the orbital periods of up to approx5.3 years. Even though the presented sample of stars is too small to make any strong conclusions, it is clear that the search for circumbinary planets is now technique-wise possible and eventually will provide new constraints for the planet formation theories.

  20. ASSEMBLY OF PROTOPLANETARY DISKS AND INCLINATIONS OF CIRCUMBINARY PLANETS

    SciTech Connect

    Foucart, Francois; Lai, Dong

    2013-02-10

    The Kepler satellite has discovered a number of transiting planets around close binary stars. These circumbinary systems have highly aligned planetary and binary orbits. In this paper, we explore how the mutual inclination between the planetary and binary orbits may reflect the physical conditions of the assembly of protoplanetary disks and the interaction between protostellar binaries and circumbinary disks. Given the turbulent nature of star-forming molecular clouds, it is possible that the gas falling onto the outer region of a circumbinary disk and the central protostellar binary have different axes of rotation. Thus, the newly assembled circumbinary disk can be misaligned with respect to the binary. However, the gravitational torque from the binary produces a warp and twist in the disk, and the back-reaction torque tends to align the disk and the binary orbital plane. We present a new, analytic calculation of this alignment torque and show that the binary-disk inclination angle can be reduced appreciably after the binary accretes a few percent of its mass from the disk. Our calculation suggests that in the absence of other disturbances, circumbinary disks and planets around close (sub-AU) stellar binaries, for which mass accretion onto the proto-binary is very likely to have occurred, are expected to be highly aligned with the binary orbits, while disks and planets around wide binaries can be misaligned. Measurements of the mutual inclinations of circumbinary planetary systems can provide a clue to the birth environments of such systems.

  1. Searching for circumbinary planets with CB-BLS

    NASA Astrophysics Data System (ADS)

    Ofir, Aviv

    2015-08-01

    Transiting circumbinary planets (CBP) produce transit signals that are neither periodic not constant in duration or depth. These complications contribute to the low number of detected transiting CBP (nine in total so far), and limited detection to systems that exhibit transits that are relatively deep, i.e. individually-significant transit events. Planets around single stars taught us that small planets far outnumber larger ones, consequently the ability to detect small CBP is of the essence in order to correctly describe CBP demographics. Unfortunately, all currently known transiting CBP were detected either by eye or by some ad-hoc technique that has nothing to do with the 3-body dynamics of CBP (e.g. QATS, Carter & Agol 2013) -- limiting their detection power. CB-BLS (Ofir 2008) is an algorithm for the detection of transiting CBP that was proposed well before the first transiting CBP was detected (Doyle et al 2011). CB-BLS is tailored for CBP dynamics and is optimally sensitive and general. Here we present further evolution and the Matlab source code of CB-BLS that allows it to detect all currently known transiting CBP, including in eccentric and/or inclined orbits. We then describe our preliminary results on searching for transiting CBP in a small subset of the Kepler eclipsing binaries.

  2. Searching for circumbinary planets with CB-BLS

    NASA Astrophysics Data System (ADS)

    Ofir, Aviv

    2015-12-01

    Transiting circumbinary planets (CBP) produce transit signals that are neither periodic not constant in duration or depth. These complications contribute to the low number of detected transiting CBP (nine published in total so far), and limited detection to systems that exhibit transits that are relatively deep, i.e. giant planets with individually-significant transit events. On the other hand, planets around single stars taught us that small planets far outnumber larger planets; consequently the ability to detect small CBPs is of the essence in order to correctly describe CBP demographics. Unfortunately, all currently known transiting CBP were detected either by eye or by some ad-hoc technique that has nothing to do with the 3-body dynamics of CBPs (e.g. QATS, Carter & Agol 2013) limiting their detection power.CB-BLS (Ofir 2008) is an algorithm for the detection of transiting CBPs that was proposed well before the first transiting CBP was detected (Doyle et al 2011) but was unfortunately not used thus far. CB-BLS was further evolved since its introduction; it is now optimally sensitive and general, it can detect transit signals that are not individually significant, and it has relatively well-understood statistical properties that allow placing limits on non-detections. As a test for its competence we show it to blindly detect all currently known transiting CBPs, including these in eccentric and/or inclined and/or very long planetary orbits that failed other techniques.We currently run a thorough search for CBPs in the Kepler dataset using CB-BLS. On top of presenting CB-BLS and it capabilities, we will give an update on the search's status and preliminary results.

  3. PLANET FORMATION IN CIRCUMBINARY CONFIGURATIONS: TURBULENCE INHIBITS PLANETESIMAL ACCRETION

    SciTech Connect

    Meschiari, Stefano

    2012-12-10

    The existence of planets born in environments highly perturbed by a stellar companion represents a major challenge to the paradigm of planet formation. In numerical simulations, the presence of a close binary companion stirs up the relative velocity between planetesimals, which is fundamental in determining the balance between accretion and erosion. However, the recent discovery of circumbinary planets by Kepler establishes that planet formation in binary systems is clearly viable. We perform N-body simulations of planetesimals embedded in a protoplanetary disk, where planetesimal phasing is frustrated by the presence of stochastic torques, modeling the expected perturbations of turbulence driven by the magnetorotational instability. We examine perturbation amplitudes relevant to dead zones in the midplane (conducive to planet formation in single stars), and find that planetesimal accretion can be inhibited even in the outer disk (4-10 AU) far from the central binary, a location previously thought to be a plausible starting point for the formation of circumbinary planets.

  4. Planet Formation in Circumbinary Configurations: Turbulence Inhibits Planetesimal Accretion

    NASA Astrophysics Data System (ADS)

    Meschiari, Stefano

    2012-12-01

    The existence of planets born in environments highly perturbed by a stellar companion represents a major challenge to the paradigm of planet formation. In numerical simulations, the presence of a close binary companion stirs up the relative velocity between planetesimals, which is fundamental in determining the balance between accretion and erosion. However, the recent discovery of circumbinary planets by Kepler establishes that planet formation in binary systems is clearly viable. We perform N-body simulations of planetesimals embedded in a protoplanetary disk, where planetesimal phasing is frustrated by the presence of stochastic torques, modeling the expected perturbations of turbulence driven by the magnetorotational instability. We examine perturbation amplitudes relevant to dead zones in the midplane (conducive to planet formation in single stars), and find that planetesimal accretion can be inhibited even in the outer disk (4-10 AU) far from the central binary, a location previously thought to be a plausible starting point for the formation of circumbinary planets.

  5. A triple origin for the lack of tight coplanar circumbinary planets around short-period binaries

    NASA Astrophysics Data System (ADS)

    Hamers, Adrian; Perets, Hagai B.; Portegies Zwart, Simon

    2015-12-01

    Detection of transiting circumbinary planets is more tractable around short-period binaries. However, sofar, no such binaries have been found with orbits shorter than 7 days. Short-period main sequence binaries have been suggested to form in triple systems, through a combination of secular Kozai-Lidov cycles and tidal friction (KLCTF). Here, we show that coplanar circumbinary transiting planets are unlikely to exist around short-period binaries, due to triple evolution. We use secular analysis, N-body simulations and analytic considerations as well as population synthesis models to characterize their overall properties. We find that the existence of a circumbinary planet in a triple is likely to produce one of the following outcomes. (1) Sufficiently massive planets in tight and/or coplanar orbits around the inner binary can partially or completely quench the KL evolution, `shielding' the inner binary from the secular effects of the tertiary, and not allowing the KLCTF process to take place. In this case, the inner binary will not shrink to become a short-period binary. (2) KL evolution is not quenched and it drives the planetary orbit into high eccentricities, giving rise to an unstable configuration, in which the planet is most likely ejected from the system. (3) KL evolution is not quenched, but the planet survives the KLCTF evolution and the formation of the short-period binary; the planet orbit is likely to be much wider than the currently observed inner binary orbit, and is likely to be inclined in respect to the binary orbit, as well as eccentric. These outcomes lead to two main conclusions: (1) it is unlikely to find a (massive) planet on a tight and coplanar orbit around a short-period main-sequence binary, and (2) the frequency, masses and orbits of non-coplanar circumbinary planets in short-period binaries are constrained by their secular evolution.

  6. Transits of planets with small intervals in circumbinary systems

    SciTech Connect

    Liu, Hui-Gen; Wang, Ying; Zhang, Hui; Zhou, Ji-Lin

    2014-08-01

    Transit times around single stars can be described well by a linear ephemeris. However, transit times in circumbinary systems are influenced both by the gravitational perturbations and the orbital phase variations of the central binary star. Adopting a coplanar analog of Kepler-16 as an example, we find that circumbinary planets can transit the same star more than once during a single planetary orbit, a phenomenon we call 'tight transits.' In certain geometric architecture, the projected orbital velocity of the planet and the secondary star can approach zero and change sign, resulting in very long transits and/or 2-3 transits during a single binary orbit. Whether tight transits are possible for a particular system depends primarily on the binary mass ratio and the orbital architecture of both the binary and the planet. We derive a time-dependent criterion to judge when tight transits are possible for any circumbinary system. These results are verified with full dynamical integrations that also reveal other tight transit characteristics, i.e., the transit durations and the intervals between tight transits. For the seven currently known circumbinary systems, we estimate these critical parameters both analytically and numerically. Due to the mutual inclination between the planet and the binary, tight transits can only occur across the less massive star B in Kepler-16, -34, -35, and -47 (for both planets). The long-term average frequency of tight transits (compared to typical transits) for Kepler-16, -34, and -35 are estimated to be several percent. Using full numerical integrations, the next tight transit for each system is predicted and the soonest example appears to be Kepler-47b and -47c, which are likely to have tight transits before 2025. These unique and valuable events often deserve special observational scrutiny.

  7. FORMATION OF CIRCUMBINARY PLANETS IN A DEAD ZONE

    SciTech Connect

    Martin, Rebecca G.; Armitage, Philip J.; Alexander, Richard D.

    2013-08-10

    Circumbinary planets have been observed at orbital radii where binary perturbations may have significant effects on the gas disk structure, on planetesimal velocity dispersion, and on the coupling between turbulence and planetesimals. Here, we note that the impact of all of these effects on planet formation is qualitatively altered if the circumbinary disk structure is layered, with a non-turbulent midplane layer (dead zone) and strongly turbulent surface layers. For close binaries, we find that the dead zone typically extends from a radius close to the inner disk edge up to a radius of around 10-20 AU from the center of mass of the binary. The peak in the surface density occurs within the dead zone, far from the inner disk edge, close to the snow line, and may act as a trap for aerodynamically coupled solids. We suggest that circumbinary planet formation may be easier near this preferential location than for disks around single stars. However, dead zones around wide binaries are less likely, and hence planet formation may be more difficult there.

  8. AN ANALYTIC THEORY FOR THE ORBITS OF CIRCUMBINARY PLANETS

    SciTech Connect

    Leung, Gene C. K.; Lee, Man Hoi

    2013-02-15

    Three transiting circumbinary planets (Kepler-16 b, Kepler-34 b, and Kepler-35 b) have recently been discovered from photometric data taken by the Kepler spacecraft. Their orbits are significantly non-Keplerian because of the large secondary-to-primary mass ratio and orbital eccentricity of the binaries, as well as the proximity of the planets to the binaries. We present an analytic theory, with the planet treated as a test particle, which shows that the planetary motion can be represented by the superposition of the circular motion of a guiding center, the forced oscillations due to the non-axisymmetric components of the binary's potential, the epicyclic motion, and the vertical motion. In this analytic theory, the periapse and ascending node of the planet precess at nearly equal rates in opposite directions. The largest forced oscillation term corresponds to a forced eccentricity (which is an explicit function of the parameters of the binary and of the guiding center radius of the planet), and the amplitude of the epicyclic motion (which is a free parameter of the theory) is the free eccentricity. Comparisons with direct numerical orbit integrations show that this analytic theory gives an accurate description of the planetary motion for all three Kepler systems. We find that all three Kepler circumbinary planets have nonzero free eccentricities.

  9. FORMING CIRCUMBINARY PLANETS: N-BODY SIMULATIONS OF KEPLER-34

    SciTech Connect

    Lines, S.; Leinhardt, Z. M.; Paardekooper, S.; Baruteau, C.; Thebault, P.

    2014-02-10

    Observations of circumbinary planets orbiting very close to the central stars have shown that planet formation may occur in a very hostile environment, where the gravitational pull from the binary should be very strong on the primordial protoplanetary disk. Elevated impact velocities and orbit crossings from eccentricity oscillations are the primary contributors to high energy, potentially destructive collisions that inhibit the growth of aspiring planets. In this work, we conduct high-resolution, inter-particle gravity enabled N-body simulations to investigate the feasibility of planetesimal growth in the Kepler-34 system. We improve upon previous work by including planetesimal disk self-gravity and an extensive collision model to accurately handle inter-planetesimal interactions. We find that super-catastrophic erosion events are the dominant mechanism up to and including the orbital radius of Kepler-34(AB)b, making in situ growth unlikely. It is more plausible that Kepler-34(AB)b migrated from a region beyond 1.5 AU. Based on the conclusions that we have made for Kepler-34, it seems likely that all of the currently known circumbinary planets have also migrated significantly from their formation location with the possible exception of Kepler-47(AB)c.

  10. PLANET HUNTERS: A TRANSITING CIRCUMBINARY PLANET IN A QUADRUPLE STAR SYSTEM

    SciTech Connect

    Schwamb, Megan E.; Schawinski, Kevin; Orosz, Jerome A.; Welsh, William F.; and others

    2013-05-10

    We report the discovery and confirmation of a transiting circumbinary planet (PH1b) around KIC 4862625, an eclipsing binary in the Kepler field. The planet was discovered by volunteers searching the first six Quarters of publicly available Kepler data as part of the Planet Hunters citizen science project. Transits of the planet across the larger and brighter of the eclipsing stars are detectable by visual inspection every {approx}137 days, with seven transits identified in Quarters 1-11. The physical and orbital parameters of both the host stars and planet were obtained via a photometric-dynamical model, simultaneously fitting both the measured radial velocities and the Kepler light curve of KIC 4862625. The 6.18 {+-} 0.17 R{sub Circled-Plus} planet orbits outside the 20 day orbit of an eclipsing binary consisting of an F dwarf (1.734 {+-} 0.044 R{sub Sun }, 1.528 {+-} 0.087 M{sub Sun }) and M dwarf (0.378 {+-} 0.023 R{sub Sun }, 0.408 {+-} 0.024 M{sub Sun }). For the planet, we find an upper mass limit of 169 M{sub Circled-Plus} (0.531 Jupiter masses) at the 99.7% confidence level. With a radius and mass less than that of Jupiter, PH1b is well within the planetary regime. Outside the planet's orbit, at {approx}1000 AU, a previously unknown visual binary has been identified that is likely bound to the planetary system, making this the first known case of a quadruple star system with a transiting planet.

  11. Survival of Planets Around Shrinking Stellar Binaries: A New Population of Misaligned Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Lai, Dong

    2015-08-01

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries known to host planets has a period shorter than 7 days, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via tidal dissipation mediated by Lidov-Kozai oscillations in orbital eccentricity induced by a distant tertiary companion. We explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may be ejected from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like.Reference: D. Munoz and D. Lai 2015, submitted

  12. A triple origin for the lack of tight coplanar circumbinary planets around short-period binaries

    NASA Astrophysics Data System (ADS)

    Hamers, Adrian S.; Perets, Hagai B.; Portegies Zwart, Simon F.

    2016-01-01

    Transiting circumbinary planets are more easily detected around short-period than long-period binaries, but none have yet been observed by Kepler orbiting binaries with periods shorter than seven days. In triple systems, secular Kozai-Lidov cycles and tidal friction (KLCTF) have been shown to reduce the inner orbital period from ˜104 to a few days. Indeed, the majority of short-period binaries are observed to possess a third stellar companion. Using secular evolution analysis and population synthesis, we show that KLCTF makes it unlikely for circumbinary transiting planets to exist around short-period binaries. We find the following outcomes. (1) Sufficiently massive planets in tight and/or coplanar orbits around the inner binary can quench the KL evolution because they induce precession in the inner binary. The KLCTF process does not take place, preventing the formation of a short-period binary. (2) Secular evolution is not quenched and it drives the planetary orbit into a high eccentricity, giving rise to an unstable configuration, in which the planet is most likely ejected from the system. (3) Secular evolution is not quenched but the planet survives the KLCTF evolution. Its orbit is likely to be much wider than the currently observed inner binary orbit, and is likely to be eccentric and inclined with respect to the inner binary. These outcomes lead to two main conclusions: (1) it is unlikely to find a massive planet on a tight and coplanar orbit around a short-period binary, and (2) the properties of circumbinary planets in short-period binaries are constrained by secular evolution.

  13. Surface flux patterns on planets in circumbinary systems and potential for photosynthesis

    NASA Astrophysics Data System (ADS)

    Forgan, Duncan H.; Mead, Alexander; Cockell, Charles S.; Raven, John A.

    2015-07-01

    Recently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on their surfaces, with features not seen in their single-star orbiting counterparts. Earth-like circumbinary planets inhabited by photosynthetic organisms will be forced to adapt to these unusual flux patterns. We map the flux received by putative Earth-like planets (as a function of surface latitude/longitude and time) orbiting the binary star systems Kepler-16 and Kepler-47, two star systems which already boast circumbinary exoplanet detections. The longitudinal and latitudinal distribution of flux is sensitive to the centre-of-mass motion of the binary, and the relative orbital phases of the binary and planet. Total eclipses of the secondary by the primary, as well as partial eclipses of the primary by the secondary add an extra forcing term to the system. We also find that the patterns of darkness on the surface are equally unique. Beyond the planet's polar circles, the surface spends a significantly longer time in darkness than latitudes around the equator, due to the stars' motions delaying the first sunrise of spring (or hastening the last sunset of autumn). In the case of Kepler-47, we also find a weak longitudinal dependence for darkness, but this effect tends to average out if considered over many orbits. In the light of these flux and darkness patterns, we consider and discuss the prospects and challenges for photosynthetic organisms, using terrestrial analogues as a guide.

  14. THE NEPTUNE-SIZED CIRCUMBINARY PLANET KEPLER-38b

    SciTech Connect

    Orosz, Jerome A.; Welsh, William F.; Short, Donald R.; Windmiller, Gur; Carter, Joshua A.; Torres, Guillermo; Geary, John C.; Brugamyer, Erik; Cochran, William D.; Endl, Michael; MacQueen, Phillip; Buchhave, Lars A.; Ford, Eric B.; Agol, Eric; Barclay, Thomas; Caldwell, Douglas A.; Clarke, Bruce D.; Doyle, Laurance R.; Fabrycky, Daniel C.; Haghighipour, Nader; and others

    2012-10-20

    We discuss the discovery and characterization of the circumbinary planet Kepler-38b. The stellar binary is single-lined, with a period of 18.8 days, and consists of a moderately evolved main-sequence star (M{sub A} = 0.949 {+-} 0.059 M {sub Sun} and R{sub A} = 1.757 {+-} 0.034 R {sub Sun }) paired with a low-mass star (M{sub B} = 0.249 {+-} 0.010 M {sub Sun} and R{sub B} = 0.2724 {+-} 0.0053 R {sub Sun }) in a mildly eccentric (e = 0.103) orbit. A total of eight transits due to a circumbinary planet crossing the primary star were identified in the Kepler light curve (using Kepler Quarters 1-11), from which a planetary period of 105.595 {+-} 0.053 days can be established. A photometric dynamical model fit to the radial velocity curve and Kepler light curve yields a planetary radius of 4.35 {+-} 0.11 R {sub Circled-Plus }, or equivalently 1.12 {+-} 0.03 R {sub Nep}. Since the planet is not sufficiently massive to observably alter the orbit of the binary from Keplerian motion, we can only place an upper limit on the mass of the planet of 122 M {sub Circled-Plus} (7.11 M {sub Nep} or equivalently 0.384 M {sub Jup}) at 95% confidence. This upper limit should decrease as more Kepler data become available.

  15. Motions of Kepler circumbinary planets in restricted three-body problem under radiating primaries

    SciTech Connect

    Dermawan, B. Hidayat, T.; Huda, I. N. Mandey, D. Utama, J. A. Tampubolon, I.; Wibowo, R. W.

    2015-09-30

    By observing continuously a single field of view in the sky, Kepler mission reveals outstanding results on discoveries of exoplanets. One of its recent progress is the discoveries of circumbinary planets. A circumbinary planet is an exoplanet that moves around a binary system. In this study we investigate motions of Kepler circumbinary planets belong to six binary systems, namely Kepler-16, -34, -35, -38, -47, and -413. The motions are considered to follow the Restricted Three-Body Problem (RTBP). Because the primaries (central massive objects) are stars, they are both radiatives, while the planet is an infinitesimal object. The primaries move in nearly circular and elliptic orbits with respect to their center of masses. We describe, in general, motions of the circumbinary planets in RTBP under radiating primaries. With respect to the averaged zero velocity curves, we show that motions of the exoplanets are stable, in accordance with their Hill stabilities.

  16. Disruption of planetary orbits through evection resonance with an external companion: circumbinary planets and multiplanet systems

    NASA Astrophysics Data System (ADS)

    Xu, Wenrui; Lai, Dong

    2016-07-01

    Planets around binary stars and those in multiplanet systems may experience resonant eccentricity excitation and disruption due to perturbations from a distant stellar companion. This `evection resonance' occurs when the apsidal precession frequency of the planet, driven by the quadrupole associated with the inner binary or the other planets, matches the orbital frequency of the external companion. We develop an analytic theory to study the effects of evection resonance on circumbinary planets and multiplanet systems. We derive the general conditions for effective eccentricity excitation or resonance capture of the planet as the system undergoes long-term evolution. Applying to circumbinary planets, we show that inward planet migration may lead to eccentricity growth due to evection resonance with an external perturber, and planets around shrinking binaries may not survive the resonant eccentricity growth. On the other hand, significant eccentricity excitation in multiplanet systems occurs in limited parameter space of planet and binary semimajor axes, and requires the planetary migration to be sufficiently slow.

  17. Kepler 453 b—The 10th Kepler Transiting Circumbinary Planet

    NASA Astrophysics Data System (ADS)

    Welsh, William F.; Orosz, Jerome A.; Short, Donald R.; Cochran, William D.; Endl, Michael; Brugamyer, Erik; Haghighipour, Nader; Buchhave, Lars A.; Doyle, Laurance R.; Fabrycky, Daniel C.; Hinse, Tobias Cornelius; Kane, Stephen R.; Kostov, Veselin; Mazeh, Tsevi; Mills, Sean M.; Müller, Tobias W. A.; Quarles, Billy; Quinn, Samuel N.; Ragozzine, Darin; Shporer, Avi; Steffen, Jason H.; Tal-Or, Lev; Torres, Guillermo; Windmiller, Gur; Borucki, William J.

    2015-08-01

    We present the discovery of Kepler-453 b, a 6.2 {R}\\oplus planet in a low-eccentricity, 240.5 day orbit about an eclipsing binary. The binary itself consists of a 0.94 and 0.195 {M}⊙ pair of stars with an orbital period of 27.32 days. The plane of the planet's orbit is rapidly precessing, and its inclination only becomes sufficiently aligned with the primary star in the latter portion of the Kepler data. Thus three transits are present in the second half of the light curve, but none of the three conjunctions that occurred during the first half of the light curve produced observable transits. The precession period is ˜103 years, and during that cycle, transits are visible only ˜8.9% of the time. This has the important implication that for every system like Kepler-453 that we detect, there are ˜11.5 circumbinary systems that exist but are not currently exhibiting transits. The planet's mass is too small to noticeably perturb the binary, and consequently its mass is not measurable with these data; however, our photodynamical model places a 1σ upper limit of 16 {M}\\oplus . With a period 8.8 times that of the binary, the planet is well outside the dynamical instability zone. It does, however, lie within the habitable zone of the binary, making it the third of 10 Kepler circumbinary planets to do so. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  18. TERRESTRIAL PLANET FORMATION AROUND THE CIRCUMBINARY HABITABLE ZONE: INWARD MIGRATION IN THE PLANETESIMAL SWARM

    SciTech Connect

    Gong Yanxiang; Zhou Jilin; Xie Jiwei E-mail: zhoujl@nju.edu.cn

    2013-01-20

    According to the core accretion theory, circumbinary embryos can form only beyond a critical semimajor axis (CSMA). However, due to the relatively high density of solid materials in the inner disk, a significant amount of small planetesimals must exist in the inner zone when embryos form outside this CSMA. Thus, embryo migration induced by the planetesimal swarm is possible after gas disk depletion. Through numerical simulations, we found that (1) the scattering-driven inward migration of embryos is robust and planets can form in the habitable zone if we adopt a mass distribution of an MMSN-like disk; (2) the total mass of the planetesimals in the inner region and continuous embryo-embryo scattering are two key factors that cause significant embryo migrations; and (3) the scattering-driven migration of embryos is a natural water-delivery mechanism. We propose that planet detections should focus on the close binary with its habitable zone near CSMA.

  19. Building Tatooine: Suppression of the Direct Secular Excitation in Kepler Circumbinary Planet Formation

    NASA Astrophysics Data System (ADS)

    Rafikov, Roman R.

    2013-02-01

    Circumbinary planetary systems recently discovered by Kepler represent an important testbed for planet formation theories. Planetesimal growth in disks around binaries has been expected to be inhibited interior to ~10 AU by secular excitation of high relative velocities between planetesimals, leading to their collisional destruction (rather than agglomeration). Here we show that gravity of an axisymmetric gaseous circumbinary disk in which planets form drives fast precession of both the planetesimal and binary orbits, resulting in strong suppression of planetesimal eccentricities beyond 2-3 AU and making possible the growth of 1-102 km objects in this region. The precise location of the boundary of the accretion-friendly region depends on the size of the inner disk cavity cleared by the binary torques and on the disk mass (even 0.01 M ⊙ disk strongly suppresses planetesimal excitation), among other things, but this zone does not extend to present orbits of Kepler circumbinary planets. The precession of the orbit of the central binary, enhanced by the mass concentration that is naturally present at the inner edge of a circumbinary disk, plays a key role in this suppression, which is a feature specific to the circumbinary planet formation.

  20. BUILDING TATOOINE: SUPPRESSION OF THE DIRECT SECULAR EXCITATION IN KEPLER CIRCUMBINARY PLANET FORMATION

    SciTech Connect

    Rafikov, Roman R.

    2013-02-10

    Circumbinary planetary systems recently discovered by Kepler represent an important testbed for planet formation theories. Planetesimal growth in disks around binaries has been expected to be inhibited interior to {approx}10 AU by secular excitation of high relative velocities between planetesimals, leading to their collisional destruction (rather than agglomeration). Here we show that gravity of an axisymmetric gaseous circumbinary disk in which planets form drives fast precession of both the planetesimal and binary orbits, resulting in strong suppression of planetesimal eccentricities beyond 2-3 AU and making possible the growth of 1-10{sup 2} km objects in this region. The precise location of the boundary of the accretion-friendly region depends on the size of the inner disk cavity cleared by the binary torques and on the disk mass (even 0.01 M{sub Sun} disk strongly suppresses planetesimal excitation), among other things, but this zone does not extend to present orbits of Kepler circumbinary planets. The precession of the orbit of the central binary, enhanced by the mass concentration that is naturally present at the inner edge of a circumbinary disk, plays a key role in this suppression, which is a feature specific to the circumbinary planet formation.

  1. Formation and Evolution of Circumbinary Planets, and the Apparent Lack of CPBs Around Short-Period Binaries

    NASA Astrophysics Data System (ADS)

    Haghighipour, Nader

    2015-12-01

    The success of the Kepler space telescope in detecting planets in circumbinary orbits strongly suggests that planet formation around binary stars is robust and planets of a variety of sizes and orbital configurations may exist in such complex environments. Accurate modeling of Kepler data has also indicated that some of these planets orbit their central binaries in close proximity to the boundary of orbital stability. This finding, combined with the unsuccessful attempts in forming circumbinary planets (CBPs) close to the orbital stability limit has lent strong support to the idea that almost all currently known CBPs have formed at large distances and undergone substantial radial migration. A survey of the currently known CBPs further indicates that these planets are mainly Neptune-mass and there seems to be a lack of planets of Jupiter-mass or larger in P-type orbits. Furthermore, an examination of the observational data obtained by the Kepler telescope seems to suggest an absence of CBPs around short-period binaries. Finally, recent detections of episodic transits in the two newly discovered circumbinary systems, Kepler 413b and Kepler 453b, as well as the discovery of Kepler non-transiting CBPs, (please see the abstract by Fabrycky et al) have indicated that in general, the orbits of planets and their host binaries are not co-planar. We present a new model for the formation and evolution of CBPs in which the migration of CBPs has been studied for low and high eccentricity binaries, and for different values of binary period. Results of our extensive hydrodynamical simulations show that planet-disk interaction in low-eccentricity binaries can account for the migration of CBPs and the proximity of their final orbits to the boundary of stability. In eccentric binaries, the situation is, however, more complex and in order to explain the final orbital architecture of the system, other factors such as planet-planet interaction have to be taken into account. We show

  2. Detection of Sharp Symmetric Features in the Circumbinary Disk around AK Sco

    NASA Astrophysics Data System (ADS)

    Janson, Markus; Thalmann, Christian; Boccaletti, Anthony; Maire, Anne-Lise; Zurlo, Alice; Marzari, Francesco; Meyer, Michael R.; Carson, Joseph C.; Augereau, Jean-Charles; Garufi, Antonio; Henning, Thomas; Desidera, Silvano; Asensio-Torres, Ruben; Pohl, Adriana

    2016-01-01

    The Search for Planets Orbiting Two Stars survey aims to study the formation and distribution of planets in binary systems by detecting and characterizing circumbinary planets and their formation environments through direct imaging. With the SPHERE Extreme Adaptive Optics instrument, a good contrast can be achieved even at small (<300 mas) separations from bright stars, which enables studies of planets and disks in a separation range that was previously inaccessible. Here, we report the discovery of resolved scattered light emission from the circumbinary disk around the well-studied young double star AK Sco, at projected separations in the ∼13–40 AU range. The sharp morphology of the imaged feature is surprising, given the smooth appearance of the disk in its spectral energy distribution. We show that the observed morphology can be represented either as a highly eccentric ring around AK Sco, or as two separate spiral arms in the disk, wound in opposite directions. The relative merits of these interpretations are discussed, as well as whether these features may have been caused by one or several circumbinary planets interacting with the disk. Based on observations collected at the European Southern Observatory, Chile, under observing program 095.C-0346(B).

  3. An Investigation of Circumbinary Planet Orbital Stability and Habitability to Identify Potential Planetary Systems with Several Habitable Planets

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Zuluaga, Jorge; Cuartas, Pablo A.

    2015-08-01

    The census of planets orbiting the center of mass of binary stars is rapidly growing. The question of stability for circumbinary planets has been the focus of much recent research. We review this work and present results of new simulations, from which we find criteria for the long term stability of exoplanets orbiting binaries. We are especially concerned with the potential stability of planets in habitable zones surrounding binaries. For this purpose, we merge a long-term orbital stability study with an analysis of the rotational evolution of the stellar components. The stellar evolution and rotational study enables estimates of stellar activity, and the effects on the magnetospheres and atmospheres of planets over the course of history for a potentially habitable circumbinary planet. We find that the long-term orbital stability of circumbinary habitable zone depends sensitively on the initial orbit of the binary and on the masses of the stars. We find that stellar twins (binary mass ratio ~ 1) and binaries with circular orbits provide the most stable solutions. However, if the binary orbit evolves too rapidly, planets may be lost due to changes in resonance locations. A subset of binaries are identified possessing both stable orbital solutions for multiple planets in the habitable zone and reduced stellar aggression due to tidal torqueing of the stellar rotation.

  4. CIRCUMBINARY PLANET FORMATION IN THE KEPLER-16 SYSTEM. I. N-BODY SIMULATIONS

    SciTech Connect

    Meschiari, Stefano

    2012-06-10

    The recently discovered circumbinary planets (Kepler-16 b, Kepler 34-b, Kepler 35-b) represent the first direct evidence of the viability of planet formation in circumbinary orbits. We report on the results of N-body simulations investigating planetesimal accretion in the Kepler-16 b system, focusing on the range of impact velocities under the influence of both stars' gravitational perturbation and friction from a putative protoplanetary disk. Our results show that planet formation might be effectively inhibited for a large range in semimajor axis (1.75 {approx}< a{sub P} {approx}< 4 AU), suggesting that the planetary core must have either migrated from outside 4 AU or formed in situ very close to its current location.

  5. A circumbinary planet in orbit around the short-period white dwarf eclipsing binary RR Cae

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Liu, L.; Zhu, L.-Y.; Dai, Z.-B.; Fernández Lajús, E.; Baume, G. L.

    2012-05-01

    By using six newly determined mid-eclipse times together with those collected from the literature, we have found that the observed minus calculated (O-C) curve of RR Cae shows a cyclic change with a period of 11.9 yr and an amplitude of 14.3 s while it undergoes an upward parabolic variation [revealing a long-term period increase at a rate of ?]. The cyclic change was analysed for the light-travel-time effect that arises from the gravitational influence of a third companion. The mass of the third body was determined to be M3sin i'= 4.2(± 0.4) MJup, suggesting that it is a circumbinary giant planet when its orbital inclination is larger than 17?6. The orbital separation of the circumbinary planet from the central eclipsing binary is about 5.3(± 0.6) au. The period increase is opposite to the changes caused by angular momentum loss via magnetic braking or/and gravitational radiation; and it cannot be explained by the mass transfer between both components because of its detached configuration. These indicate that the observed upward parabolic change is only a part of a long-period (longer than 26.3 yr) cyclic variation, which may reveal the presence of another giant circumbinary planet in a wide orbit.

  6. ROTATIONAL SYNCHRONIZATION MAY ENHANCE HABITABILITY FOR CIRCUMBINARY PLANETS: KEPLER BINARY CASE STUDIES

    SciTech Connect

    Mason, Paul A.; Zuluaga, Jorge I.; Cuartas-Restrepo, Pablo A.; Clark, Joni M.

    2013-09-10

    We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

  7. Rotational Synchronization May Enhance Habitability for Circumbinary Planets: Kepler Binary Case Studies

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Zuluaga, Jorge I.; Clark, Joni M.; Cuartas-Restrepo, Pablo A.

    2013-09-01

    We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

  8. CIRCUMBINARY PLANETS ORBITING THE RAPIDLY PULSATING SUBDWARF B-TYPE BINARY NY Vir

    SciTech Connect

    Qian, S.-B.; Zhu, L.-Y.; Dai, Z.-B.; He, J.-J.; Xiang, F.-Y.

    2012-02-15

    We report here the tentative discovery of a Jovian planet in orbit around the rapidly pulsating subdwarf B-type (sdB-type) eclipsing binary NY Vir. By using newly determined eclipse times together with those collected from the literature, we detect that the observed-calculated (O - C) curve of NY Vir shows a small-amplitude cyclic variation with a period of 7.9 yr and a semiamplitude of 6.1 s, while it undergoes a downward parabolic change (revealing a period decrease at a rate of P-dot = -9.2 x 10{sup -12}). The periodic variation was analyzed for the light-travel-time effect via the presence of a third body. The mass of the tertiary companion was determined to be M{sub 3}sin i' = 2.3({+-} 0.3)M{sub Jupiter} when a total mass of 0.60 M{sub Sun} for NY Vir is adopted. This suggests that it is most probably a giant circumbinary planet orbiting NY Vir at a distance of about 3.3 astronomical units (AU). Since the rate of period decrease cannot be explained by true angular momentum loss caused by gravitational radiation or/and magnetic braking, the observed downward parabolic change in the O - C diagram may be only a part of a long-period (longer than 15 years) cyclic variation, which may reveal the presence of another Jovian planet ({approx}2.5 M{sub Jupiter}) in the system.

  9. Kepler-1647b: The Largest and Longest-period Kepler Transiting Circumbinary Planet

    NASA Astrophysics Data System (ADS)

    Kostov, Veselin B.; Orosz, Jerome A.; Welsh, William F.; Doyle, Laurance R.; Fabrycky, Daniel C.; Haghighipour, Nader; Quarles, Billy; Short, Donald R.; Cochran, William D.; Endl, Michael; Ford, Eric B.; Gregorio, Joao; Hinse, Tobias C.; Isaacson, Howard; Jenkins, Jon M.; Jensen, Eric L. N.; Kane, Stephen; Kull, Ilya; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Mazeh, Tsevi; Müller, Tobias W. A.; Pepper, Joshua; Quinn, Samuel N.; Ragozzine, Darin; Shporer, Avi; Steffen, Jason H.; Torres, Guillermo; Windmiller, Gur; Borucki, William J.

    2016-08-01

    We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (∼1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With a radius of 1.06 ± 0.01 R Jup, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 ± 0.65 M Jup. The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric (e bin = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth’s, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.

  10. Kepler-1647b: The Largest and Longest-period Kepler Transiting Circumbinary Planet

    NASA Astrophysics Data System (ADS)

    Kostov, Veselin B.; Orosz, Jerome A.; Welsh, William F.; Doyle, Laurance R.; Fabrycky, Daniel C.; Haghighipour, Nader; Quarles, Billy; Short, Donald R.; Cochran, William D.; Endl, Michael; Ford, Eric B.; Gregorio, Joao; Hinse, Tobias C.; Isaacson, Howard; Jenkins, Jon M.; Jensen, Eric L. N.; Kane, Stephen; Kull, Ilya; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Mazeh, Tsevi; Müller, Tobias W. A.; Pepper, Joshua; Quinn, Samuel N.; Ragozzine, Darin; Shporer, Avi; Steffen, Jason H.; Torres, Guillermo; Windmiller, Gur; Borucki, William J.

    2016-08-01

    We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (˜1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With a radius of 1.06 ± 0.01 R Jup, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 ± 0.65 M Jup. The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric (e bin = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth’s, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.

  11. KIC-5473556: the largest and longest-period Kepler transiting circumbinary planet

    NASA Astrophysics Data System (ADS)

    Kostov, Veselin

    2015-12-01

    We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of short-period CBPs orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet in the KIC-5473556 system has a very long orbital period (~1100 days) and was at conjunction only twice during the Kepler mission -- making it the longest-period transiting CBP at the time of writing. With a radius of nearly 12 REarth, it is also the largest such planet to date. It produced three transits in the light curve of KIC 5473556, one of them during a syzygy. The planet revolves around an ~11-day Eclipsing Binary consisting of two Solar-mass stars on a slightly inclined to the line of sight, mildly eccentric (ebin = 0.16) orbit. The CBP measurably perturbs the times of the stellar eclipses, allowing us to constrain its mass well. Here we present our spectroscopic and photometric observations of the target, discuss our analysis of the system, and outline the theoretical implications of our discovery.

  12. Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable-zone Planets

    NASA Astrophysics Data System (ADS)

    Zuluaga, Jorge I.; Mason, Paul A.; Cuartas-Restrepo, Pablo A.

    2016-02-01

    The discovery of many planets using the Kepler telescope includes 10 planets orbiting eight binary stars. Three binaries, Kepler-16, Kepler-47, and Kepler-453, have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogs provide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by Mason et al. Kepler-453 has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.

  13. TWO POSSIBLE CIRCUMBINARY PLANETS IN THE ECLIPSING POST-COMMON ENVELOPE SYSTEM NSVS 14256825

    SciTech Connect

    Almeida, L. A.; Jablonski, F.; Rodrigues, C. V.

    2013-03-20

    We present an analysis of eclipse timings of the post-common envelope binary NSVS 14256825, which is composed of an sdOB star and a dM star in a close orbit (P{sub orb} = 0.110374 days). High-speed photometry of this system was performed between 2010 July and 2012 August. Ten new mid-eclipse times were analyzed together with all available eclipse times in the literature. We revisited the (O - C) diagram using a linear ephemeris and verified a clear orbital period variation. On the assumption that these orbital period variations are caused by light travel time effects, the (O - C) diagram can be explained by the presence of two circumbinary bodies, even though this explanation requires a longer baseline of observations to be fully tested. The orbital periods of the best solution would be P{sub c} {approx} 3.5 years and P{sub d} {approx} 6.9 years. The corresponding projected semi-major axes would be a{sub c} sin i{sub c} {approx} 1.9 AU and a{sub d} sin i{sub d} {approx} 2.9 AU. The masses of the external bodies would be M{sub c} {approx} 2.9 M{sub Jupiter} and M{sub d} {approx} 8.1 M{sub Jupiter}, if we assume their orbits are coplanar with the close binary. Therefore NSVS 14256825 might be composed of a close binary with two circumbinary planets, though the orbital period variations is still open to other interpretations.

  14. Kepler-413B: A slightly misaligned, Neptune-size transiting circumbinary planet

    SciTech Connect

    Kostov, V. B.; McCullough, P. R.; Tsvetanov, Z. I.; Carter, J. A.; Deleuil, M.; Díaz, R. F.; Fabrycky, D. C.; Hébrard, G.; Hinse, T. C.; Mazeh, T.; Orosz, J. A.; Welsh, W. F.

    2014-03-20

    We report the discovery of a transiting, R{sub p} = 4.347 ± 0.099R {sub ⊕}, circumbinary planet (CBP) orbiting the Kepler K+M eclipsing binary (EB) system KIC 12351927 (Kepler-413) every ∼66 days on an eccentric orbit with a{sub p} = 0.355 ± 0.002 AU, e{sub p} = 0.118 ± 0.002. The two stars, with M{sub A} = 0.820 ± 0.015 M {sub ☉}, R{sub A} = 0.776 ± 0.009 R {sub ☉} and M{sub B} = 0.542 ± 0.008 M {sub ☉}, R{sub B} = 0.484 ± 0.024 R {sub ☉}, respectively, revolve around each other every 10.11615 ± 0.00001 days on a nearly circular (e {sub EB} = 0.037 ± 0.002) orbit. The orbital plane of the EB is slightly inclined to the line of sight (i {sub EB} = 87.°33 ± 0.°06), while that of the planet is inclined by ∼2.°5 to the binary plane at the reference epoch. Orbital precession with a period of ∼11 yr causes the inclination of the latter to the sky plane to continuously change. As a result, the planet often fails to transit the primary star at inferior conjunction, causing stretches of hundreds of days with no transits (corresponding to multiple planetary orbital periods). We predict that the next transit will not occur until 2020. The orbital configuration of the system places the planet slightly closer to its host stars than the inner edge of the extended habitable zone. Additionally, the orbital configuration of the system is such that the CBP may experience Cassini State dynamics under the influence of the EB, in which the planet's obliquity precesses with a rate comparable to its orbital precession. Depending on the angular precession frequency of the CBP, it could potentially undergo obliquity fluctuations of dozens of degrees (and complex seasonal cycles) on precession timescales.

  15. SPIN-ORBIT ALIGNMENT FOR THE CIRCUMBINARY PLANET HOST KEPLER-16 A

    SciTech Connect

    Winn, Joshua N.; Albrecht, Simon; Johnson, John Asher; Torres, Guillermo; Carter, Joshua A.; Ragozzine, Darin; Quinn, Samuel N.; Latham, David W.; Cochran, William D.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Fischer, Debra; Doyle, Laurance; Welsh, William; Orosz, Jerome; Fabrycky, Daniel C.; Shporer, Avi; Howell, Steve B.; Prsa, Andrej

    2011-11-01

    Kepler-16 is an eccentric low-mass eclipsing binary with a circumbinary transiting planet. Here, we investigate the angular momentum of the primary star, based on Kepler photometry and Keck spectroscopy. The primary star's rotation period is 35.1 {+-} 1.0 days, and its projected obliquity with respect to the stellar binary orbit is 1.{sup 0}6 {+-} 2.{sup 0}4. Therefore, the three largest sources of angular momentum-the stellar orbit, the planetary orbit, and the primary's rotation-are all closely aligned. This finding supports a formation scenario involving accretion from a single disk. Alternatively, tides may have realigned the stars despite their relatively wide separation (0.2 AU), a hypothesis that is supported by the agreement between the measured rotation period and the 'pseudosynchronous' period of tidal evolution theory. The rotation period, chromospheric activity level, and fractional light variations suggest a main-sequence age of 2-4 Gyr. Evolutionary models of low-mass stars can match the observed masses and radii of the primary and secondary stars to within about 3%.

  16. HOW NOT TO BUILD TATOOINE: THE DIFFICULTY OF IN SITU FORMATION OF CIRCUMBINARY PLANETS KEPLER 16b, KEPLER 34b, AND KEPLER 35b

    SciTech Connect

    Paardekooper, Sijme-Jan; Baruteau, Clement; Leinhardt, Zoee M.; Thebault, Philippe

    2012-07-20

    We study planetesimal evolution in circumbinary disks, focusing on the three systems Kepler 16, 34, and 35 where planets have been discovered recently. We show that for circumbinary planetesimals, in addition to secular forcing, eccentricities evolve on a dynamical timescale, which leads to orbital crossings even in the presence of gas drag. This makes the current locations of the circumbinary Kepler planets hostile to planetesimal accretion. We then present results from simulations including planetesimal formation and dust accretion, and show that even in the most favorable case of 100% efficient dust accretion, in situ growth starting from planetesimals smaller than {approx}10 km is difficult for Kepler 16b, Kepler 34b, and Kepler 35b. These planets were likely assembled further out in the disk, and migrated inward to their current location.

  17. Circumbinary planet formation in the Kepler-16 system. II. A toy model for in situ planet formation within a debris belt

    SciTech Connect

    Meschiari, Stefano

    2014-07-20

    Recent simulations have shown that the formation of planets in circumbinary configurations (such as those recently discovered by Kepler) is dramatically hindered at the planetesimal accretion stage. The combined action of the binary and the protoplanetary disk acts to raise impact velocities between kilometer-sized planetesimals beyond their destruction threshold, halting planet formation within at least 10 AU from the binary. It has been proposed that a primordial population of 'large' planetesimals (100 km or more in size), as produced by turbulent concentration mechanisms, would be able to bypass this bottleneck; however, it is not clear whether these processes are viable in the highly perturbed circumbinary environments. We perform two-dimensional hydrodynamical and N-body simulations to show that kilometer-sized planetesimals and collisional debris can drift and be trapped in a belt close to the central binary. Within this belt, planetesimals could initially grow by accreting debris, ultimately becoming 'indestructible' seeds that can accrete other planetesimals in situ despite the large impact speeds. We find that large, indestructible planetesimals can be formed close to the central binary within 10{sup 5} yr, therefore showing that even a primordial population of 'small' planetesimals can feasibly form a planet.

  18. Extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Korechoff, R. P.; Diner, D. J.; Tubbs, E. F.; Gaiser, S. L.

    1994-01-01

    This paper discusses the concept of extrasolar planet detection using a large-aperture infared imaging telescope. Coronagraphic stellar apodization techniques are less efficient at infrared wavelengths compared to the visible, as a result of practical limitations on aperture dimensions, thus necessitating additional starlight suppression to make planet detection feasible in this spectral domain. We have been investigating the use of rotational shearing interferometry to provide up to three orders of magnitude of starlight suppression over broad spectral bandwidths. We present a theoretical analysis of the system performance requirements needed to make this a viable instrument for planet detection, including specifications on the interferometer design and telescope aperture characteristics. The concept of using rotational shearing interferometry as a wavefront error detector, thus providing a signal that can be used to adaptively correct the wavefront, will be discussed. We also present the status of laboratory studies of on-axis source suppression using a recently constructed rotational shearing interferometer that currently operates in the visible.

  19. Circumbinary Planetary Systems at Home and Abroad

    NASA Astrophysics Data System (ADS)

    Kratter, Kaitlin M.; Shannon, Andrew B.; Youdin, Andrew; Kenyon, Scott

    2014-05-01

    The Kepler mission has revealed a new class of (main-sequence) planetary system: circumbinaries. In these systems, a tight binary is orbited by one or more planets. From a dynamical perspective, these systems are not new, but rather a scaled up version of the Pluto-Charon system. In this talk I will discuss what we can learn from a detailed study of the dynamics of both Pluto-Charon and Kepler circumbinary systems. I will describe how circumbinary planets may be crucial for our understanding of binary star formation, and why these unique systems may be excellent places to search for habitable zone planets.

  20. A GAS GIANT CIRCUMBINARY PLANET TRANSITING THE F STAR PRIMARY OF THE ECLIPSING BINARY STAR KIC 4862625 AND THE INDEPENDENT DISCOVERY AND CHARACTERIZATION OF THE TWO TRANSITING PLANETS IN THE KEPLER-47 SYSTEM

    SciTech Connect

    Kostov, V. B.; Tsvetanov, Z. I.; McCullough, P. R.; Valenti, J. A.; Hinse, T. C.; Hebrard, G.; Diaz, R. F.; Deleuil, M.

    2013-06-10

    We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47. We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For the KIC 4862625 system, the 0.52 {+-} 0.018 R{sub Jupiter} radius planet revolves every {approx}138 days and occults the 1.47 {+-} 0.08 M{sub Sun }, 1.7 {+-} 0.06 R{sub Sun} F8 IV primary star producing aperiodic transits of variable durations commensurate with the configuration of the eclipsing binary star. Our best-fit model indicates the orbit has a semi-major axis of 0.64 AU and is slightly eccentric, e = 0.1. For the Kepler-47 system, we confirm the results of Orosz et al. Modulations in the radial velocity of KIC 4862625A are measured both spectroscopically and photometrically, i.e., via Doppler boosting, and produce similar results.

  1. SPOTS: The Search for Planets Orbiting Two Stars. II. First constraints on the frequency of sub-stellar companions on wide circumbinary orbits

    NASA Astrophysics Data System (ADS)

    Bonavita, M.; Desidera, S.; Thalmann, C.; Janson, M.; Vigan, A.; Chauvin, G.; Lannier, J.

    2016-09-01

    A large number of direct imaging surveys for exoplanets have been performed in recent years, yielding the first directly imaged planets and providing constraints on the prevalence and distribution of wide planetary systems. However, like most of the radial velocity ones, these generally focus on single stars, hence binaries and higher-order multiples have not been studied to the same level of scrutiny. This motivated the Search for Planets Orbiting Two Stars (SPOTS) survey, which is an ongoing direct imaging study of a large sample of close binaries, started with VLT/NACO and now continuing with VLT/SPHERE. To complement this survey, we have identified the close binary targets in 24 published direct imaging surveys. Here we present our statistical analysis of this combined body of data. We analysed a sample of 117 tight binary systems, using a combined Monte Carlo and Bayesian approach to derive the expected values of the frequency of companions, for different values of the companion's semi-major axis. Our analysis suggest that the frequency of sub-stellar companions in wide orbit is moderately low (≲ 13% with a best value of 6% at 95% confidence level) and not significantly different between single stars and tight binaries. One implication of this result is that the very high frequency of circumbinary planets in wide orbits around post-common envelope binaries, implied by eclipse timing, cannot be uniquely due to planets formed before the common-envelope phase (first generation planets), supporting instead the second generation planet formation or a non-Keplerian origin of the timing variations.

  2. DETECTING VOLCANISM ON EXTRASOLAR PLANETS

    SciTech Connect

    Kaltenegger, L.; Sasselov, D. D.; Henning, W. G.

    2010-11-15

    The search for extrasolar rocky planets has already found the first transiting rocky super-Earth, Corot 7b, with a surface temperature that allows for magma oceans. Here, we investigate whether we could distinguish rocky planets with recent major volcanism by remote observation. We develop a model for volcanic eruptions on an Earth-like exoplanet based on the present-day Earth and derive the observable features in emergent and transmission spectra for multiple scenarios of gas distribution and cloud cover. We calculate the observation time needed to detect explosive volcanism on exoplanets in primary as well as secondary eclipse and discuss the likelihood of observing volcanism on transiting Earth-sized to super-Earth-sized exoplanets. We find that sulfur dioxide from large explosive eruptions does present a spectral signal that is remotely detectable especially for secondary eclipse measurements around the closest stars and ground-based telescopes, and report the frequency and magnitude of the expected signatures. The transit probability of a planet in the habitable zone decreases with distance from the host star, making small, nearby host stars the best targets.

  3. Progress in extra-solar planet detection

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.

    1991-01-01

    Progress in extra-solar planet detection is reviewed. The following subject areas are covered: (1) the definition of a planet; (2) the weakness of planet signals; (3) direct techniques - imaging and spectral detection; and (4) indirect techniques - reflex motion and occultations.

  4. The Architecture of Circumbinary Systems

    NASA Astrophysics Data System (ADS)

    Smullen, Rachel; Kratter, Kaitlin M.

    2015-12-01

    Transiting circumbinary planets, as discovered by Kepler, provide unique insight into planet formation and planetary dynamics. These planets are low mass (about Neptune or smaller) and reside close to the stability limit of the binary. The question then becomes nature or nurture? Have circumbinary disks preferentially formed low mass, close in planets, or have dynamical processes sculpted the system into what we observe? We used N-body simulations to explore the impact of planet-planet scattering on the orbital architecture of four planetary populations around both single and binary stars. I will present the similarities and differences in the resultant planet populations. For instance, the final multiplicity is similar between single and binary stars, but planets in binary systems are much more likely to eject than collide. I will address the observable multiplicity and other unique characteristics our simulations have revealed. With this work and future observations, we will be able to better understand the underlying initial planetary distributions around binary stars and the formation mechanisms that allow these systems to form.

  5. Detecting Planets Outside The Solar System

    NASA Technical Reports Server (NTRS)

    Pravdo, Steven H.; Terrile, Richard J.; Ftaclas, Christ; Gatewood, George

    1993-01-01

    Report describes proposed Astrometric Imaging Telescope, used to detect planets in orbit around distant stars. Includes executive summary and statement of scientific objectives of Astrometric Imaging Telescope program.

  6. Planet Detection: The Kepler Mission

    NASA Astrophysics Data System (ADS)

    Jenkins, Jon M.; Smith, Jeffrey C.; Tenenbaum, Peter; Twicken, Joseph D.; Van Cleve, Jeffrey

    2012-03-01

    The search for exoplanets is one of the hottest topics in astronomy and astrophysics in the twenty-first century, capturing the public's attention as well as that of the astronomical community. This nascent field was conceived in 1989 with the discovery of a candidate planetary companion to HD114762 [35] and was born in 1995 with the discovery of the first extrasolar planet 51 Peg-b [37] orbiting a main sequence star. As of March, 2011, over 500 exoplanets have been discovered* and 106 are known to transit or cross their host star, as viewed from Earth. Of these transiting planets, 15 have been announced by the Kepler Mission, which was launched into an Earth-trailing, heliocentric orbit in March, 2009 [1,4,6,15,18,20,22,31,32,34,36,43]. In addition, over 1200 candidate transiting planets have already been detected by Kepler [5], and vigorous follow-up observations are being conducted to vet these candidates. As the false-positive rate for Kepler is expected to be quite low [39], Kepler has effectively tripled the number of known exoplanets. Moreover, Kepler will provide an unprecedented data set in terms of photometric precision, duration, contiguity, and number of stars. Kepler's primary science objective is to determine the frequency of Earth-size planets transiting their Sun-like host stars in the habitable zone, that range of orbital distances for which liquid water would pool on the surface of a terrestrial planet such as Earth, Mars, or Venus. This daunting task demands an instrument capable of measuring the light output from each of over 100,000 stars simultaneously with an unprecedented photometric precision of 20 parts per million (ppm) at 6.5-h intervals. The large number of stars is required because the probability of the geometrical alignment of planetary orbits that permit observation of transits is the ratio of the size of the star to the size of the planetary orbit. For Earth-like planets in 1-astronomical unit (AU) orbits† about sun-like stars

  7. A Planet Detection Tutorial and Simulator

    NASA Technical Reports Server (NTRS)

    Knoch, David; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Detection of extra-solar planets has been a very popular topic with the general public for years. Considerable media coverage of recent detections (currently at about 50) has only heightened the interest in the topic. School children are particularly interested in learning about recent astronomical discoveries. Scientists have the knowledge and responsibility to present this information in both an understandable and interesting format. Most classrooms and homes are now connected to the internet, which can be utilized to provide more than a traditional 'flat' presentation. An interactive software package on planet detection has been developed. The major topics include: "1996 - The Break Through Year In Planet Detection"; "What Determines If A Planet Is Habitable?"; "How Can We Find Other Planets (Search Methods)"; "All About the Kepler Mission: How To Find Terrestrial Planets"; and "A Planet Detection Simulator". Using the simulator, the student records simulated observations and then analyzes and interprets the data within the program. One can determine the orbit and planet size, the planet's temperature and surface gravity, and finally determine if the planet is habitable. Originally developed for the Macintosh, a web based browser version is being developed.

  8. Planet Detection: The Kepler Mission

    NASA Astrophysics Data System (ADS)

    Jenkins, Jon M.; Smith, Jeffrey C.; Tenenbaum, Peter; Twicken, Joseph D.; Van Cleve, Jeffrey

    2012-03-01

    The search for exoplanets is one of the hottest topics in astronomy and astrophysics in the twenty-first century, capturing the public's attention as well as that of the astronomical community. This nascent field was conceived in 1989 with the discovery of a candidate planetary companion to HD114762 [35] and was born in 1995 with the discovery of the first extrasolar planet 51 Peg-b [37] orbiting a main sequence star. As of March, 2011, over 500 exoplanets have been discovered* and 106 are known to transit or cross their host star, as viewed from Earth. Of these transiting planets, 15 have been announced by the Kepler Mission, which was launched into an Earth-trailing, heliocentric orbit in March, 2009 [1,4,6,15,18,20,22,31,32,34,36,43]. In addition, over 1200 candidate transiting planets have already been detected by Kepler [5], and vigorous follow-up observations are being conducted to vet these candidates. As the false-positive rate for Kepler is expected to be quite low [39], Kepler has effectively tripled the number of known exoplanets. Moreover, Kepler will provide an unprecedented data set in terms of photometric precision, duration, contiguity, and number of stars. Kepler's primary science objective is to determine the frequency of Earth-size planets transiting their Sun-like host stars in the habitable zone, that range of orbital distances for which liquid water would pool on the surface of a terrestrial planet such as Earth, Mars, or Venus. This daunting task demands an instrument capable of measuring the light output from each of over 100,000 stars simultaneously with an unprecedented photometric precision of 20 parts per million (ppm) at 6.5-h intervals. The large number of stars is required because the probability of the geometrical alignment of planetary orbits that permit observation of transits is the ratio of the size of the star to the size of the planetary orbit. For Earth-like planets in 1-astronomical unit (AU) orbits† about sun-like stars

  9. Detection of Terrestrial Planets Using Transit Photometry

    NASA Technical Reports Server (NTRS)

    Koch, David; Witteborn, Fred; Jenkins, Jon; Dunham, Edward; Boruci, William; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Transit photometry detection of planets offers many advantages: an ability to detect terrestrial size planets, direct determination of the planet's size, applicability to all main-sequence stars, and a differential brightness change of the periodic signature being independent of stellar distance or planetary orbital semi-major axis. Ground and space based photometry have already been successful in detecting transits of the giant planet HD209458b. However, photometry 100 times better is required to detect terrestrial planets. We present results of laboratory measurements of an end-to-end photometric system incorporating all of the important confounding noise features of both the sky and a space based photometer including spacecraft jitter. In addition to demonstrating an instrumental noise of less than 10 ppm (an Earth transit of a solar-like star is 80 ppm), the brightnesses of individual stars were dimmed to simulate Earth-size transit signals. These 'transits' were reliably detected as part of the tests.

  10. Planet Detection Algorithms for the Terrestrial Planet Finder-C

    NASA Astrophysics Data System (ADS)

    Kasdin, N. J.; Braems, I.

    2005-12-01

    Critical to mission planning for the terrestrial planet finder coronagraph (TPF-C) is the ability to estimate integration times for planet detection. This detection is complicated by the presence of background noise due to local and exo-zodiacal dust, by residual speckle due optical errors, and by the dependence of the PSF shape on the specific coronagraph. In this paper we examine in detail the use of PSF fitting (matched filtering) for planet detection, derive probabilistic bounds for the signal-to-noise ratio by balancing missed detection and false alarm rates, and demonstrate that this is close to the optimal linear detection technique. We then compare to a Bayesian detection approach and show that for very low background the Bayesian method offers integration time improvements, but rapidly approaches the PSF fitting result for reasonable levels of background noise. We confirm via monte-carlo simulations. This work was supported under a grant from the Jet Propulsion Laboratory and by a fellowship from the Institut National de Recherche en Informatique et Automatique (INRIA).

  11. Super-earth Detection and "Planet Fever"

    NASA Astrophysics Data System (ADS)

    Pont, Frederic; Aigrain, S.; Zucker, S.

    2009-09-01

    Radial-velocity spectrographs and space transit searches have become sensitive enough to detect planets only a few times more massive than the Earth - the telluric planets or "super-Earths." We are getting one step nearer to knowing how common are Earth analogs. There is a catch however: many of the super-Earth detections are very close to the detection thresholds, and intrinsic stellar variations are an important source of false positive with both the radial velocity and transit technique. In preparation for the coming harvest of new detections, it seems worth attempting to develop some vaccine against the most extreme strands of "planet fever," the contagious disease of seeing extra-solar planet in any signal.

  12. DETECTION OF A GIANT EXTRASOLAR PLANET ORBITING THE ECLIPSING POLAR DP LEO

    SciTech Connect

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

    2010-01-01

    DP Leo is the first discovered eclipsing polar with a short period of 1.4967 hours. The period variation of the eclipsing binary was analyzed by using five new determined eclipse times together with those compiled from the literature. It is discovered that the O - C curve of DP Leo shows a cyclic variation with a period of 23.8 years and a semiamplitude of 31.5 s. The small-amplitude periodic change can be plausibly explained as the light-travel time effect due to the presence of a tertiary companion. The mass of the tertiary component is determined to be M {sub 3}sin i' = 0.00600({+-}0.00055) M {sub sun} = 6.28({+-}0.58) M {sub Jupiter} when a total mass of 0.69 M {sub sun} is adopted. If the tertiary companion is coplanar to the eclipsing binary (i.e., i' = 79.{sup 0}5), it should be a giant extrasolar planet with a mass of 6.39 M {sub Jupiter} at a distance of 8.6 astronomical units to the central binary. One of the most interesting things that we have learned about extrasolar planets over the last 17 years is that they can exist almost anywhere. The detection of a giant planet orbiting a polar would provide insight into the formation and evolution of circumbinary planets (planets orbiting both components of short-period binaries) as well as the late evolution of binary stars.

  13. Terrestrial Planet Finder, Planet Detection Test-Bed: Latest Results of Planet Light Detection in the Presence of Starlight

    NASA Technical Reports Server (NTRS)

    Martin, Stefan R.; Booth, Andrew J.

    2008-01-01

    The Terrestrial Planet Finder, Planet Detection Test-bed is a lab based simulation of the optics and control systems for the Terrestrial Planet Finder Interferometer mission. The test-bed supports starlight nulling at 10um infrared wavelengths, with fringe tracking at 2um wavelengths and angle and shear tracking at visible wavelengths. It further allows injection of simulated planet light in the presence of the nulled star light, to allow testing of planet detection methods. We will describe the detailed construction and operation of the test-bed from an optical and control system perspective. We will also report the latest results for narrow band nulls, and the detection of broad band planet light in the presence of nulled starlight.

  14. Circumbinary habitability niches

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Zuluaga, Jorge I.; Cuartas-Restrepo, Pablo A.; Clark, Joni M.

    2015-07-01

    Binaries could provide the best niches for life in the Galaxy. Although counterintuitive, this assertion follows directly from stellar tidal interaction theory and the evolution of lower mass stars. There is strong evidence that chromospheric activity of rapidly rotating young stars may be high enough to cause mass loss from atmospheres of potentially habitable planets. The removal of atmospheric water is most critical. Tidal breaking in binaries could help reduce magnetic dynamo action and thereby chromospheric activity in favour of life. We call this the Binary Habitability Mechanism (BHM) that we suggest allows for water retention at levels comparable to or better than the Earth. We discuss novel advantages that life may exploit, in these cases, and suggest that life may even thrive on some circumbinary planets. We find that while many binaries do not benefit from BHM, high-quality niches do exist for various combinations of stars between 0.55 and 1.0 solar masses. For a given pair of stellar masses, BHM operates only for certain combinations of period and eccentricity. Binaries having a solar-type primary seem to be quite well-suited niches having wide and distant habitable zones with plentiful water and sufficient light for photosynthetic life. We speculate that, as a direct result of BHM, conditions may be suitable for life on several planets and possibly even moons of giant planets orbiting some binaries. Lower mass combinations, while more restrictive in parameter space, provide niches lasting many billions of years and are rich suppliers of photosynthetic photons. We provide a publicly available web-site (http://bit.ly/BHM-calculator or http://bit.ly/BHM-calculator-mirror), which calculates the BHM effects presented in this paper.

  15. Microlensing detection of extrasolar planets.

    PubMed

    Giannini, Emanuela; Lunine, Jonathan I

    2013-05-01

    We review the method of exoplanetary microlensing with a focus on two-body planetary lensing systems. The physical properties of planetary systems can be successfully measured by means of a deep analysis of lightcurves and high-resolution imaging of planetary systems, countering the concern that microlensing cannot determine planetary masses and orbital radii. Ground-based observers have had success in diagnosing properties of multi-planet systems from a few events, but space-based observations will be much more powerful and statistically more complete. Since microlensing is most sensitive to exoplanets beyond the snow line, whose statistics, in turn, allow for testing current planetary formation and evolution theories, we investigate the retrieval of semi-major axis density by a microlensing space-based survey with realistic parameters. Making use of a published statistical method for projected exoplanets quantities (Brown 2011), we find that one year of such a survey might distinguish between simple power-law semi-major axis densities. We conclude by briefly reviewing ground-based results hinting at a high abundance of free-floating planets and describing the potential contribution of space-based missions to understanding the frequency and mass distribution of these intriguing objects, which could help unveil the formation processes of planetary systems. PMID:23604071

  16. Secular and tidal evolution of circumbinary systems

    NASA Astrophysics Data System (ADS)

    Correia, Alexandre C. M.; Boué, Gwenaël; Laskar, Jacques

    2016-08-01

    We investigate the secular dynamics of three-body circumbinary systems under the effect of tides. We use the octupolar non-restricted approximation for the orbital interactions, general relativity corrections, the quadrupolar approximation for the spins, and the viscous linear model for tides. We derive the averaged equations of motion in a simplified vectorial formalism, which is suitable to model the long-term evolution of a wide variety of circumbinary systems in very eccentric and inclined orbits. In particular, this vectorial approach can be used to derive constraints for tidal migration, capture in Cassini states, and stellar spin-orbit misalignment. We show that circumbinary planets with initial arbitrary orbital inclination can become coplanar through a secular resonance between the precession of the orbit and the precession of the spin of one of the stars. We also show that circumbinary systems for which the pericenter of the inner orbit is initially in libration present chaotic motion for the spins and for the eccentricity of the outer orbit. Because our model is valid for the non-restricted problem, it can also be applied to any three-body hierarchical system such as star-planet-satellite systems and triple stellar systems.

  17. ON THE HABITABLE ZONES OF CIRCUMBINARY PLANETARY SYSTEMS

    SciTech Connect

    Kane, Stephen R.; Hinkel, Natalie R.

    2013-01-01

    The effect of the stellar flux on exoplanetary systems is becoming an increasingly important property as more planets are discovered in the habitable zone (HZ). The Kepler mission has recently uncovered circumbinary planets with relatively complex HZs due to the combined flux from the binary host stars. Here, we derive HZ boundaries for circumbinary systems and show their dependence on the stellar masses, separation, and time while accounting for binary orbital motion and the orbit of the planet. We include stability regimes for planetary orbits in binary systems with respect to the HZ. These methods are applied to several of the known circumbinary planetary systems such as Kepler-16, 34, 35, and 47. We also quantitatively show the circumstances under which single-star approximations break down for HZ calculations.

  18. Systematic aspects of direct extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.

    1988-01-01

    Using the first optical observatory in space, the Hubble Space Telescope, images of possible extrasolar planets will have poor contrast against the background of diffracted and scattered starlight. The very long exposure time required to achieve an adequate signal-to-noise ratio will make their detection infeasible. For a future telescope, a 16-fold increase in either the smoothness of the collecting area of the optics would reduce the exposure time to a tolerable value, but the contrast would remain low and the required photometric precision high. In this situation, the feasibility of detection would be contingent on the careful identification and control of systematic errors.

  19. Radial Velocity Detection of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Kaye, T. G.

    2004-05-01

    Spectroscopy has long been an ignored corner of amateur astronomy and is generally regarded as difficult if not impossible with small telescopes. With the advent of robotic scopes and high efficiency CCD's, this aspect of astronomy is now open for exploration. The Spectrashift.com project is a team of amateurs that have constructed and implemented a spectrograph and tele- scope system capable of measuring radial velocities down to approximately 100 meters per second. This level of precision can detect extrasolar planets known as "hot Jupiters". The system's performance has been demonstrated on the star Tau Boötis.

  20. Progress in testing exo-planet signal extraction on the TPF-I Planet Detection Testbed

    NASA Technical Reports Server (NTRS)

    Martin, Stefan R.; Szwaykowski, Piotr; Loya, Frank M.; Liewer, Kurt

    2006-01-01

    The TPF Interferometer (TPF-I) concept is being studied at the Jet Propulsion Laboratory and the TPF-I Planet Detection Testbed has been developed to simulate the detection process for an earthlike planet orbiting a star within about 15 pc. The testbed combines four beams of infrared light simulating the operation of a dual chopped Bracewell interferometer observing a star and a faint planet. This paper describes the results obtained this year including nulling of the starlight on four input beams at contrast ratios up to 250,000 to 1, and detection of faint planet signals at contrast ratios with the star of 2 million to 1.

  1. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Webster, Larry; Dunham, Edward; Witteborn, Fred; Jenkins, Jon; Caldwell, Douglas; Showen, Robert; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A knowledge of other planetary systems that includes information on the number, size, mass, and spacing of the planets around a variety of star types is needed to deepen our understanding of planetary system formation and processes that give rise to their final configurations. Recent discoveries show that many planetary systems are quite different from the solar system in that they often possess giant planets in short period orbits. The inferred evolution of these planets and their orbital characteristics imply the absence of Earth-like planets near the habitable zone. Information on the properties of the giant-inner planets is now being obtained by both the Doppler velocity and the transit photometry techniques. The combination of the two techniques provides the mass, size, and density of the planets. For the planet orbiting star HD209458, transit photometry provided the first independent confirmation and measurement of the diameter of an extrasolar planet. The observations indicate a planet 1.27 the diameter of Jupiter with 0.63 of its mass (Charbonneau et al. 1999). The results are in excellent agreement with the theory of planetary atmospheres for a planet of the indicated mass and distance from a solar-like star. The observation of the November 23, 1999 transit of that planet made by the Ames Vulcan photometer at Lick Observatory is presented. In the future, the combination of the two techniques will greatly increase the number of discoveries and the richness of the science yield. Small rocky planets at orbital distances from 0.9 to 1.2 AU are more likely to harbor life than the gas giant planets that are now being discovered. However, new technology is needed to find smaller, Earth-like planets, which are about three hundred times less massive than Jupiter-like planets. The Kepler project is a space craft mission designed to discover hundreds of Earth-size planets in and near the habitable zone around a wide variety of stars. To demonstrate that the

  2. Extrasolar Binary Planets II: Detectability by Transit Observations

    NASA Astrophysics Data System (ADS)

    Lewis, K. M.; Ochiai, H.; Nagasawa, M.; Ida, S.

    2015-05-01

    We discuss the detectability of gravitationally bound pairs of gas-giant planets (which we call “binary planets”) in extrasolar planetary systems that are formed through orbital instability followed by planet-planet dynamical tides during their close encounters, based on the results of N-body simulations by Ochiai et al. (Paper I). Paper I showed that the formation probability of a binary is as much as ˜10% for three giant planet systems that undergo orbital instability, and after post-capture long-term tidal evolution, the typical binary separation is three to five times the sum of the physical radii of the planets. The binary planets are stable during the main-sequence lifetime of solar-type stars, if the stellarcentric semimajor axis of the binary is larger than 0.3 AU. We show that detecting modulations of transit light curves is the most promising observational method to detect binary planets. Since the likely binary separations are comparable to the stellar diameter, the shape of the transit light curve is different from transit to transit, depending on the phase of the binary’s orbit. The transit durations and depth for binary planet transits are generally longer and deeper than those for the single planet case. We point out that binary planets could exist among the known inflated gas-giant planets or objects classified as false positive detections at orbital radii ≳0.3 AU, propose a binary planet explanation for the CoRoT candidate SRc01 E2 1066, and show that binary planets are likely to be present in, and could be detected using, Kepler-quality data.

  3. MEMS-based extreme adaptive optics for planet detection

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Graham, James; Oppenheimer, Ben; Poyneer, Lisa; Sivaramakrishnan, Anand; Veran, Jean-Pierre

    2006-01-01

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today - the realm of "Extreme" adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order "woofer" mirror), and a fully-functional 48-actuator-diameter aperture.

  4. MEMS-based extreme adaptive optics for planet detection

    SciTech Connect

    Macintosh, B A; Graham, J R; Oppenheimer, B; Poyneer, L; Sivaramakrishnan, A; Veran, J

    2005-11-18

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today--the realm of ''Extreme'' adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order ''woofer'' mirror), and a fully-functional 48-actuator-diameter aperture.

  5. Kepler Mission to Detect Earth-like Planets

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji

    2003-01-01

    Kepler Mission to detect Earth-like planets in our Milky Way galaxy was approved by NASA in December 2001 for a 4-5 year mission. The launch is planned in about 5 years. The Kepler observatory will be placed in an Earth-trailing orbit. The unique feature of the Kepler Mission is its ability to detect Earth-like planets orbiting around solar-type stars at a distance similar to that of Earth (from our Sun); such an orbit could provide an environment suitable for supporting life as we know it. The Kepler observatory accomplishes this feat by looking for the transits of planetary object in front of their suns; Kepler has a photometric precision of 10E-5 (0.00001) to achieve such detections. Other ongoing planetary detection programs (based mostly on a technique that looks for the shifting of spectral lines of the primary star due to its planetary companions' motions around it) have detected massive planets (with masses in the range of Jupiter); such massive planets are not considered suitable for supporting life. If our current theories for the formation of planetary systems are valid, we expect to detect about 50 Earth-like planets during Kepler's 4-year mission (assuming a random distribution of the planetary orbital inclinations with respect to the line of sight from Kepler). The number of detection will increase about 640 planets if the planets to be detected are Jupiter-sized.

  6. Kepler Mission to Detect Earth-like Planets

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji

    2002-01-01

    Kepler Mission to detect Earth-like planets in our Milky Way galaxy was approved by NASA in December 2001 for a 4-5 year mission. The launch is planned in about 5 years. The Kepler observatory will be placed in an Earth-trailing orbit. The unique feature of the Kepler Mission is its ability to detect Earth-like planets orbiting around solar-type stars at a distance similar to that of Earth (from our Sun); such an orbit could provide an environment suitable for supporting life as we know it. The Kepler observatory accomplishes this feat by looking for the transits of planetary object in front of their suns; Kepler has a photometric precision of 10E-5 (0.00001) to achieve such detections. Other ongoing planetary detection programs (based mostly on a technique that looks for the shifting of spectral lines of the primary star due to its planetary companions' motions around it) have detected massive planets (with masses in the range of Jupiter); such massive planets are not considered suitable for supporting life. If our current theories for the formation of planetary systems are valid, we expect to detect about 50 Earth-like planets during Kepler's 4-year mission (assuming a random distribution of the planetary orbital inclinations with respect to the line of sight from Kepler). The number of detection will increase about 640 planets if the planets to be detected are Jupiter-sized.

  7. Developments in Planet Detection using Transit Timing Variations

    SciTech Connect

    Steffen, Jason H.; Agol, Eric; /Washington U., Seattle, Astron. Dept.

    2006-12-01

    In a transiting planetary system, the presence of a second planet will cause the time interval between transits to vary. These transit timing variations (TTV) are particularly large near mean-motion resonances and can be used to infer the orbital elements of planets with masses that are too small to detect by any other means. The author presents the results of a study of simulated data where they show the potential that this planet detection technique has to detect and characterize secondary planets in transiting systems. These results have important ramifications for planetary transit searches since each transiting system presents an opportunity for additional discoveries through a TTV analysis. They present such an analysis for 13 transits of the HD 209458 system that were observed with the Hubble Space Telescope. This analysis indicates that a putative companion in a low-order, mean-motion resonance can be no larger than the mass of the Earth and constitutes, to date, the most sensitive probe for extrasolar planets that orbit main sequence stars. The presence or absence of small planets in low-order, mean-motion resonances has implications for theories of the formation and evolution of planetary systems. Since TTV is most sensitive in these regimes, it should prove a valuable tool not only for the detection of additional planets in transiting systems, but also as a way to determine the dominant mechanisms of planet formation and the evolution of planetary systems.

  8. Detectability of the Reflection Signal from Inner Planets

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Jenkins, J. M.; Scargle, J.; Koch, D.; Doyle, L. R.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    Mayor and Queloz (1996) and Marcy and Butler (1996) have found massive planets with orbital periods Tp=approx.4 days around two solar-like stars (51 Pegasi and v Andromeda). These planets are most likely similar in size and composition to the gas giants in our solar system (Burrows et al 1996). Based on this expectation and assuming the same albedo as Jupiter, we examined the feasibility of searching for similar planets with a dedicated space-based 1-m telescope. The Kepler mission will survey approximately 70,000 main-sequence dwarf stars from 9 to 14 mag continuously for four years to detect transiting Earthlike planets. Based on the detection statistics of Marcy and Butler, we expect to detect 1400 inner-orbit giant planets. Such planets in a much wider range of orbital inclinations (i) will produce nearly sinusoidal modulations of the star light flux due to the varying planetary phases. The relative signal amplitudes are of order 2x10(exp -5) and decrease as Tp(exp 4/3) for i >> 0deg. We estimated the expected signal to noise ratio (SNR) using the solar irradiance measurements from the ACRIM 1 experiment along with expected shot and detector noises. The figure shows SNR as a function of Tp for a 12 mag star, and indicates the planet radius required for detection. The survey will be sensitive to planets with periods from 12 hr to approx.8 days at the 6 sigma level.

  9. Survival of planets around shrinking stellar binaries

    NASA Astrophysics Data System (ADS)

    Munoz, Diego Jose; Lai, Dong

    2015-12-01

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 days, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. We present new results (PNAS 112, 30, p 9264) on the orbital evolution of planets around binaries undergoing orbital decay by this "LK+tide" mechanism. From secular and N-body calculations, we show how planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Either outcome can explain these planets' elusiveness to detection. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer specific predictions as to what their orbital configurations should be like.

  10. Possibilities for the detection of microbial life on extrasolar planets.

    PubMed

    Knacke, Roger F

    2003-01-01

    We consider possibilities for the remote detection of microbial life on extrasolar planets. The Darwin/Terrestrial Planet Finder (TPF) telescope concepts for observations of terrestrial planets focus on indirect searches for life through the detection of atmospheric gases related to life processes. Direct detection of extraterrestrial life may also be possible through well-designed searches for microbial life forms. Satellites in Earth orbit routinely monitor colonies of terrestrial algae in oceans and lakes by analysis of reflected ocean light in the visible region of the spectrum. These remote sensing techniques suggest strategies for extrasolar searches for signatures of chlorophylls and related photosynthetic compounds associated with life. However, identification of such life-related compounds on extrasolar planets would require observations through strong, interfering absorptions and scattering radiances from the remote atmospheres and landmasses. Techniques for removal of interfering radiances have been extensively developed for remote sensing from Earth orbit. Comparable techniques would have to be developed for extrasolar planet observations also, but doing so would be challenging for a remote planet. Darwin/TPF coronagraph concepts operating in the visible seem to be best suited for searches for extrasolar microbial life forms with instruments that can be projected for the 2010-2020 decades, although resolution and signal-to-noise ratio constraints severely limit detection possibilities on terrestrial-type planets. The generation of telescopes with large apertures and extremely high spatial resolutions that will follow Darwin/TPF could offer striking possibilities for the direct detection of extrasolar microbial life. PMID:14678662

  11. Hubble Telescope Detects 'Sunscreen' Layer on Distant Planet

    NASA Video Gallery

    Using NASA’s Hubble Telescope, scientists detected a stratosphere on the planet WASP-33b. A stratosphere occurs when molecules in the atmosphere absorb ultraviolet and visible light from the star. ...

  12. Formation and Detectability of Terrestrial Planets Around Alpha Centauri B

    NASA Astrophysics Data System (ADS)

    Guedes, Javiera

    2009-01-01

    Alpha Centauri B belongs to a triple star system comprised of a central A/B binary and a third companion, Proxima Centauri. The system, our closest stellar neighbor, is of great interest for planet hunters because it may harbor Earth-mass planets possibly in the habitable zone of the stars of the A/B binary. To assess whether terrestrial planets can indeed form around these stars, we run a series of N-body accretionary simulations of a 1/r disk populated with 400-900 lunar-mass oligarchs is followed for 200 Myr. All simulations lead to the formation of multiple-planet systems with at least one planet in the 1-2 M_Earth mass range at 0.5-1.5 AU. We examine the detectability of our simulated planetary systems by generating synthetic radial velocity observations including noise. Using these synthetic observations, we find that we can reliably detect a 1.8 M_Earth planet in the habitable zone of Alpha Centauri B after only three years of high cadence observations. The observations will be carried out at the CTIO site in northern Chile on a 1.5-m underutilized telescope. We expect to report the detection (or non-detection) of Earth-like planets around Alpha Centauri B in 3 to 5 years.

  13. Tatooine Nurseries: Structure and Evolution of Circumbinary Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Vartanyan, David; Garmilla, José A.; Rafikov, Roman R.

    2016-01-01

    Recent discoveries of circumbinary planets by the Kepler mission provide motivation for understanding their birthplaces—protoplanetary disks around stellar binaries with separations ≲ 1 {{AU}}. We explore properties and evolution of such circumbinary disks focusing on modification of their structure caused by tidal coupling to the binary. We develop a set of analytical scaling relations describing viscous evolution of the disk properties, which are verified and calibrated using 1D numerical calculations with realistic inputs. Injection of angular momentum by the central binary suppresses mass accretion onto the binary and causes radial distribution of the viscous angular momentum flux {F}J to be different from that in a standard accretion disk around a single star with no torque at the center. Disks with no mass accretion at the center develop an {F}J profile that is flat in radius. Radial profiles of temperature and surface density are also quite different from those in disks around single stars. Damping of the density waves driven by the binary and viscous dissipation dominates heating of the inner disk (within 1-2 AU), pushing the ice line beyond 3-5 AU, depending on disk mass and age. Irradiation by the binary governs disk thermodynamics beyond ˜10 AU. However, self-shadowing by the hot inner disk may render central illumination irrelevant out to ˜20 AU. Spectral energy distribution of a circumbinary disk exhibits a distinctive bump around 10 μm, which may facilitate identification of such disks around unresolved binaries. Efficient tidal coupling to the disk drives orbital inspiral of the binary and may cause low-mass and relatively compact binaries to merge into a single star within the disk lifetime. We generally find that circumbinary disks present favorable sites for planet formation (despite their wider zone of volatile depletion), in agreement with the statistics of Kepler circumbinary planets.

  14. On the stability of circumbinary planetary systems

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Shevchenko, I. I.

    2016-07-01

    The dynamics of circumbinary planetary systems (the systems in which the planets orbit a central binary) with a small binary mass ratio discovered to date is considered. The domains of chaotic motion have been revealed in the "pericentric distance-eccentricity" plane of initial conditions for the planetary orbits through numerical experiments. Based on an analytical criterion for the chaoticity of planetary orbits in binary star systems, we have constructed theoretical curves that describe the global boundary of the chaotic zone around the central binary for each of the systems. In addition, based on Mardling's theory describing the separate resonance "teeth" (corresponding to integer resonances between the orbital periods of a planet and the binary), we have constructed the local boundaries of chaos. Both theoretical models are shown to describe adequately the boundaries of chaos on the numerically constructed stability diagrams, suggesting that these theories are efficient in providing analytical criteria for the chaoticity of planetary orbits.

  15. Extrasolar Terrestrial Planets: Can We Detect Them Already?

    NASA Astrophysics Data System (ADS)

    Endl, M.; Kürster, M.; Rouesnel, F.; Els, S.; Hatzes, A. P.; Cochran, W. D.

    With the example of Proxima Centauri we discuss the feasibility of detecting terrestrial planets (1 to a few Earth masses) using the high precision radial velocity (RV) technique. If a very high RV precision for M stars is achieved even planets with these extremely low masses become detectable. For Proxima Cen (M5V), one of the prime targets of our M stars planet search program using the UVES spectrograph and iodine cell at the ESO VLT UT2, we obtain a long term RV precision of 2.5 m/sec. Based on numerical simulations we determine that this level of precision would have already allowed us to detect planets with M sin i= 4 to 6 Earth masses inside the habitable zone of Proxima Cen.

  16. Kepler Planet-Detection Mission: Introduction and First Results

    SciTech Connect

    Borucki, William J.; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John; Christensen-Dalsgaard, Jorgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; /Lowell Observ. /Harvard-Smithsonian Ctr. Astrophys.

    2010-01-01

    The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet's surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets ({approx}0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.

  17. The Keck Planet Search: Detectability and the Minimum Mass and Orbital Period Distribution of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Cumming, Andrew; Butler, R. Paul; Marcy, Geoffrey W.; Vogt, Steven S.; Wright, Jason T.; Fischer, Debra A.

    2008-05-01

    We analyze 8 years of precise radial velocity measurements from the Keck Planet Search, characterizing the detection threshold, selection effects, and completeness of the survey. We first carry out a systematic search for planets, by assessing the false-alarm probability associated with Keplerian orbit fits to the data. This allows us to understand the detection threshold for each star in terms of the number and time baseline of the observations, and the underlying "noise" from measurement errors, intrinsic stellar jitter, or additional low-mass planets. We show that all planets with orbital periods P < 2000 days, velocity amplitudes K > 20 m s-1, and eccentricities e lsim 0.6 have been announced, and we summarize the candidates at lower amplitudes and longer orbital periods. For the remaining stars, we calculate upper limits on the velocity amplitude of a companion. For orbital periods less than the duration of the observations, these are typically 10 m s-1 and increase vprop P2 for longer periods. We then use the nondetections to derive completeness corrections at low amplitudes and long orbital periods and discuss the resulting distribution of minimum mass and orbital period. We give the fraction of stars with a planet as a function of minimum mass and orbital period and extrapolate to long-period orbits and low planet masses. A power-law fit for planet masses >0.3 MJ and periods < 2000 days gives a mass-period distribution dN = CMαPβd ln Md ln P with α = -0.31 ± 0.2, β = 0.26 ± 0.1, and the normalization constant C such that 10.5% of solar type stars have a planet with mass in the range 0.3-10 MJ and orbital period 2-2000 days. The orbital period distribution shows an increase in the planet fraction by a factor of ≈5 for orbital periods gsim300 days. Extrapolation gives 17%-20% of stars having gas giant planets within 20 AU. Finally, we constrain the occurrence rate of planets orbiting M dwarfs compared to FGK dwarfs, taking into account differences in

  18. Detecting Tree-like Multicellular Life on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Doughty, Christopher E.; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.

  19. Detecting tree-like multicellular life on extrasolar planets.

    PubMed

    Doughty, Christopher E; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems

  20. Planet detectability by an adaptive optics stellar coronagraph

    NASA Astrophysics Data System (ADS)

    Nakajima, T.

    1994-04-01

    We show the possibilities for imaging Jupiter-like planets around nearby bright stars, assuming the availability of stellar coronagraphs coupled with modest adaptive optics mounted on large ground-based telescopes. The adaptive optics sharpens the point-spread function (PSF) of the planet, permits the use of an occulting disk smaller than the seeing disk, reduces the PSF envelope of the bright star, and therefore enhances the contrast between the planet and background. We have generated the PSF of the planet and the PSF envelope of the main star, using Monte Carlo simulations based on the Kolmogorov theory of turbulence. We calculate the signal-to-noise ratio of a model planet as a function of the angular separation based on photon statistics and realistic assumptions on the system performance. We have derived a criterion for optimizing the combination of the degree of adaptive compensation and the telescope diameter. It is found that a stellar coronagraph with modest adaptive optics mounted on a large ground-based telescope will be capable of detecting Jupiter-like planets around nearby bright stars such as alpha Cen, Sirius, and Procyon at wavelengths between 0.7 and 2.2 micrometers. Near-infrared observations are preferred because usable telescopes and isoplanatic angles are larger at infrared wavelengths than optical wavelengths for a given adaptive optics system. We have also found seven other target stars around which planets will be above the detection limit.

  1. Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

    2007-04-24

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

  2. Eclipsing Binaries: Precise Clocks to Detect Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Kundra, Emil; Pribulla, Theodor; Vaňko, Martin; Hambálek, Ľubomír

    2014-04-01

    Project Dwarf is a new observing campaign focused on the detection of substellar companions to low-mass (composed of late-type, subdwarf (sd) or/and white dwarf (WD) components) detached eclipsing binaries using minima timing. The crucial condition for the object selection for this campaign is possibility to determine times of the minima with high precision. This is naturally fullfilled for eclipsing binaries with deep and narrow minima or systems hosting a WD component showing fast ingress or egress. The observing project includes three groups of close eclipsing binaries indicating presence of substellar circum-binary components: (i) systems with K or/and M dwarf components (ii) systems with hot subdwarf (sd) and M dwarf components (iii) systems with white dwarf (WD) component(s). The sample of the eclipsing systems have orbital periods in range of 0.1 to almost 3 days and their brightness fits possibilities of small telescopes equipped with a low-end CCD camera and at least VRI filter set. Such kind of telescopes allow us to develop observing network including also amateur astronomers.

  3. Photometric Detection of Extra-Solar Planets

    NASA Technical Reports Server (NTRS)

    Hatzes, Artie P.; Cochran, William D.

    2004-01-01

    This NASA Origins Program grant supported the TEMPEST Texas McDonald Photometric Extrasolar Search for Transits) program at McDonald Observatory, which searches for transits of extrasolar planets across the disks of their parent stars. The basic approach is to use a wide-field ground-based telescope (in our case the McDonald Observatory 0.76m telescope and it s Prime Focus Corrector) to search for transits of short period (1-15 day orbits) of close-in hot-Jupiter planets in orbit around a large sample of field stars. The next task is to search these data streams for possible transit events. We collected our first set of test data for this program using the 0.76 m PFC in the summer of 1998. From those data, we developed the optimal observing procedures, including tailoring the stellar density, exposure times, and filters to best-suit the instrument and project. In the summer of 1999, we obtained the first partial season of data on a dedicated field in the constellation Cygnus. These data were used to develop and refine the reduction and analysis procedures to produce high-precision photometry and search for transits in the resulting light curves. The TeMPEST project subsequently obtained three full seasons of data on six different fields using the McDonald Observatory 0.76m PFC.

  4. Detection of the Magnetospheric Emissions from Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Lazio, J.

    2014-12-01

    Planetary-scale magnetic fields are a window to a planet's interior and provide shielding of the planet's atmosphere. The Earth, Mercury, Ganymede, and the giant planets of the solar system all contain internal dynamo currents that generate planetary-scale magnetic fields. These internal dynamo currents arise from differential rotation, convection, compositional dynamics, or a combination of these. If coupled to an energy source, such as the incident kinetic or magnetic energy from the solar wind, a planet's magnetic field can produce electron cyclotron masers in its magnetic polar regions. The most well known example of this process is the Jovian decametric emission, but all of the giant planets and the Earth contain similar electron cyclotron masers within their magnetospheres. Extrapolated to extrasolar planets, the remote detection of the magnetic field of an extrasolar planet would provide a means of obtaining constraints on the thermal state, composition, and dynamics of its interior as well as improved understanding of the basic planetary dynamo process. The magnetospheric emissions from solar system planets and the discovery of extrasolar planets have motivated both theoretical and observational work on magnetospheric emissions from extrasolar planets. Stimulated by these advances, the W.M. Keck Institute for Space Studies hosted a workshop entitled "Planetary Magnetic Fields: Planetary Interiors and Habitability." I summarize the current observational status of searches for magnetospheric emissions from extrasolar planets, based on observations from a number of ground-based radio telescopes, and future prospects for ground-based studies. Using the solar system planetary magnetic fields as a guide, future space-based missions will be required to study planets with magnetic field strengths lower than that of Jupiter. I summarize mission concepts identified in the KISS workshop, with a focus on the detection of planetary electron cyclotron maser emission. The

  5. Detection of extrasolar planets by the large deployable reflector

    NASA Technical Reports Server (NTRS)

    Hollenbach, D. J.; Takahashi, T.

    1984-01-01

    The best wavelength for observing Jupiter-size planetary companions to stars other than the Sun is one at which a planet's thermal emission is strongest; typically this would occur in the far-infrared region. It is assumed that the orbiting infrared telescope used is diffraction-limited so that the resolution of the planet from the central star is accomplished in the wings of the star's Airy pattern. Proxima Centauri, Barnard's Star, Wolf 359, and Epsilon Eridani are just a few of the many nearest main-sequence stars that could be studied with the large deployable relfector (LDR). The detectability of a planet improves for warmer planets and less luminous stars; therefore, planets around white dwarfs and those young planets which have sufficient internal gravitational energy release so as to cause a significant increase in their temperatures are considered. If white dwarfs are as old as they are usually assumed to be (5-10 billion yr), then only the nearest white dwarf (Sirius B) is within the range of LDR. The Ursa Major cluster and Perseu cluster are within LDR's detection range mainly because of their proximity and young age, respectively.

  6. Kepler Planet-Detection Mission: Introduction and First Results

    NASA Astrophysics Data System (ADS)

    Borucki, William J.; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Dupree, Andrea K.; Gautier, Thomas N.; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Kondo, Yoji; Latham, David W.; Marcy, Geoffrey W.; Meibom, Søren; Kjeldsen, Hans; Lissauer, Jack J.; Monet, David G.; Morrison, David; Sasselov, Dimitar; Tarter, Jill; Boss, Alan; Brownlee, Don; Owen, Toby; Buzasi, Derek; Charbonneau, David; Doyle, Laurance; Fortney, Jonathan; Ford, Eric B.; Holman, Matthew J.; Seager, Sara; Steffen, Jason H.; Welsh, William F.; Rowe, Jason; Anderson, Howard; Buchhave, Lars; Ciardi, David; Walkowicz, Lucianne; Sherry, William; Horch, Elliott; Isaacson, Howard; Everett, Mark E.; Fischer, Debra; Torres, Guillermo; Johnson, John Asher; Endl, Michael; MacQueen, Phillip; Bryson, Stephen T.; Dotson, Jessie; Haas, Michael; Kolodziejczak, Jeffrey; Van Cleve, Jeffrey; Chandrasekaran, Hema; Twicken, Joseph D.; Quintana, Elisa V.; Clarke, Bruce D.; Allen, Christopher; Li, Jie; Wu, Haley; Tenenbaum, Peter; Verner, Ekaterina; Bruhweiler, Frederick; Barnes, Jason; Prsa, Andrej

    2010-02-01

    The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (~0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.

  7. Spectral Astrometry Mission for Planets Detection

    SciTech Connect

    Erskine, D J; Edelstein, J

    2002-08-09

    The Spectral Astrometry Mission is a space-mission concept that uses simultaneous, multiple-star differential astrometry to measure exo-solar planet masses. The goal of SAM is to measure the reflex motions of hundreds of nearby ({approx}50 pc) F, G and K stars, relative to adjacent stars, with a resolution of 2.5 {micro}-arcsec. SAM is a new application of Spectral Interferometry (SI), also called Externally Dispersed Interferometry (EDI), that can simultaneously measure the angular difference between the target and multiple reference stars. SI has demonstrated the ability to measure a {lambda}/20,000 white-light fringe shift with only {lambda}/3 baseline control. SAM's structural stability and compensation requirements are therefore dramatically reduced compared to existing long-arm balanced-arm interferometric astrometry methods. We describe the SAM's mission concept, long-baseline SI astrometry method, and technical challenges to achieving the mission.

  8. Apparent Stellar Wobble by a Planet in a Circumstellar Disk: Limitations on Planet Detection by Astrometry

    NASA Technical Reports Server (NTRS)

    Takeuchi, Taku; Velusamy, T.; Lin, D. N. C.

    2005-01-01

    Astrometric detection of a stellar wobble on the plane of the sky will provide us the next breakthrough in searching for extrasolar planets. The Space Interferometry Mission (SIM) is expected to achieve high-precision astrometry as accurate as 1 (mu)as, which is precise enough to discover a newborn Jupiter mass planet around a pre-main-sequence (PMS) star in the Taurus-Auriga star-forming region. PMS stars, however, have circumstellar disks that may be obstacles to the precise measurement of the stellar position.We present results on disk influences on the stellar wobble. The density waves excited by a planet move both the disk's mass center and the photocenter. The motion of the disk mass center induces an additional wobble of the stellar position, and the motion of the disk photocenter causes a contamination in the measurement of the stellar position. We show that the additional stellar motion dynamically caused by the disk's gravity is always negligible but that the contamination by the disk light can interfere with the precise measurement of the stellar position if the planet's mass is smaller than approximately 10MJ. The motion of the disk photocenter is sensitive to a slight change in the wave pattern and the disk properties. Measurements by interferometers are generally insensitive to extended sources such as disks. Because of this property, SIM will not suffer significant contamination by the disk light, even if the planet's mass is as small as 1M(sub J).

  9. The photometric method of extrasolar planet detection revisited

    NASA Technical Reports Server (NTRS)

    Hale, Alan; Doyle, Laurance R.

    1994-01-01

    We investigate the geometry concerning the photometric method of extrasolar planet detection, i.e., the detection of dimunition of a parent star's brightness during a planetary transit. Under the assumption that planetary orbital inclinations can be defined by a Gaussian with a sigma of 10 deg centered on the parent star's equatorial plane, Monte Carlo simulations suggest that for a given star observed at an inclination of exactly 90 deg, the probability of at least one Earth-sized or larger planet being suitably placed for transits is approximately 4%. This probability drops to 3% for a star observed at an inclination of 80 deg, and is still approximately 0.5% for a star observed at an inclination of 60 deg. If one can select 100 stars with a pre-determined inclination equal or greater than 80 deg, the probability of at least one planet being suitably configured for transits is 95%. The majority of transit events are due to planets in small-a orbits similar to the Earth and Venus; thus, the photometric method in principle is the method best suited for the detection of Earthlike planets. The photometric method also allows for testing whether or not planets can exist within binary systems. This can ge done by selecting binary systems observed at high orbital inclinations, both eclipsing binaries and wider visual binaries. For a 'real-world' example, we look at the alpha Centauri system (i = 79.2 deg). If we assume that the equatorial planes of both components coincide with the system's orbital plane, Monte Carlo simulations suggest that the probability of at least one planet (of either component) being suitably configured for transits is approximately 8%. In conclusion, we present a non-exhaustive list of solar-type stars, both single and within binary systems, which exhibit a high equatorial inclination. These objects may be considered as preliminary candidates for planetary searches via the photometric method.

  10. Nature or nurture of coplanar Tatooines: the aligned circumbinary Kuiper belt analogue around HD 131511

    NASA Astrophysics Data System (ADS)

    Kennedy, Grant M.

    2015-02-01

    A key discovery of the Kepler mission is of the circumbinary planets known as `Tatooines', which appear to be well aligned with their host stars' orbits. Whether this alignment is due to initially coplanar circumbinary planet-forming discs (i.e. nature), or subsequent alignment of initially misaligned discs by warping the inner disc or torquing the binary (i.e. nurture), is not known. Tests of which scenario dominates may be possible by observing circumbinary Kuiper belt analogues (`debris discs'), which trace the plane of the primordial disc. Here, the 140 au diameter circumbinary debris disc around HD 131511 is shown to be aligned to within 10° of the plane of the near edge-on 0.2 au binary orbit. The stellar equator is also consistent with being in this plane. If the primordial disc was massive enough to pull the binary into alignment, this outcome should be common and distinguishing nature versus nurture will be difficult. However, if only the inner disc becomes aligned with the binary, the HD 131511 system was never significantly misaligned. Given an initial misalignment, the ˜ Gyr main-sequence lifetime of the star allows secular perturbations to align the debris disc out to 100 au at the cost of an increased scaleheight. The observed debris disc scaleheight limits any misalignment to less than 25°. With only a handful known, many more such systems need to be characterized to help test whether the alignment of circumbinary planets is nature or nurture.

  11. Spectroscopic direct detection of reflected light from extrasolar planets

    NASA Astrophysics Data System (ADS)

    Martins, J. H. C.; Figueira, P.; Santos, N. C.; Lovis, C.

    2013-12-01

    At optical wavelengths, an exoplanet's signature is essentially reflected light from the host star - several orders of magnitude fainter. Since it is superimposed on the star spectrum its detection has been a difficult observational challenge. However, the development of a new generation of instruments like Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) and next-generation telescopes like the European Extremely Large Telescope (E-ELT) put us in a privileged position to detect these planets' reflected light as we will have access to extremely high signal-to-noise ratio spectra. With this work, we propose an alternative approach for the direct detection of the reflected light of an exoplanet. We simulated observations with ESPRESSO at Very Large Telescope (VLT) and high-resolution spectrograph (HIRES) at E-ELT of several star+planet systems, encompassing 10 h of the most favourable orbital phases. To the simulated spectra we applied the cross-correlation function to operate in a much higher signal-to-noise ratio domain than when compared with the spectra. The use of the cross-correlation function permitted us to recover the simulated planet signals at a level above 3σnoise significance on several prototypical (e.g. Neptune-type planet with a 2 d orbit with the VLT at 4.4σnoise significance) and real planetary systems (e.g. 55 Cnc e with the E-ELT at 4.9σnoise significance). Even by using a more pessimistic approach to the noise level estimation, where systematics in the spectra increase the noise 2-3 times, the detection of the reflected light from large close-orbit planets is possible. We have also shown that this kind of study is currently within reach of current instruments and telescopes (e.g. 51 Peg b with the VLT at 5.2σnoise significance), although at the limit of their capabilities.

  12. 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; Mohanty, Subhanjoy; Prato, L.; Simon, Michal

    2008-01-01

    We present a review of precursor observing programs for the SIM PlanetQuest Key project devoted to detecting Jupiter mass planets around young stars. In order to ensure that the stars in the sample are free of various sources of astrometric noise that might impede the detection of planets, we have initiated programs to collect photometry, high contrast images, interferometric data and radial velocities for stars in both the Northern and Southern hemispheres. We have completed a high contrast imaging survey of target stars in Taurus and the Pleiades and found no definitive common proper motion companions within one arcsecond (140 AU) of the SIM targets. Our radial velocity surveys have shown that many of the target stars in Sco-Cen are fast rotators and a few stars in Taurus and the Pleiades may have sub-stellar companions. Interferometric data of a few stars in Taurus show no signs of stellar or sub-stellar companions with separations of <5 mas. The photometric survey suggests that approximately half of the stars initially selected for this program are variable to a degree (1(sigma) >0.1 mag) that would degrade the astrometric accuracy achievable for that star. While the precursor programs are still a work in progress, we provide a comprehensive list of all targets ranked according to their viability as a result of the observations taken to date. By far, the observable that removes the most targets from the SIM-YSO program is photometric variability.

  13. Pilot Study of Enhanced Minor Planet Detection Using NEOWISE Data

    NASA Astrophysics Data System (ADS)

    Cukrov, Greta; Mainzer, A. K.; Bauer, J. M.; Grav, T.; Masiero, J. R.; Cutri, R. M.; Wright, E. L.; Nugent, C.; Stevenson, R.; Clyne, E.; Masci, F. J.

    2014-01-01

    The solar system science component of NASA’s Wide-field Infrared Survey Explorer (WISE), known as NEOWISE, extracted detections of more than 158,000 asteroids and comets, including 34,000 new discoveries. These objects were detected through a search algorithm that actively rejected inertially fixed sources such as stars and galaxies and selected candidate moving objects through the construction of position-time pairs known as tracklets. A minimum of five detections were required in order to construct a tracklet; this system enabled the discovery of new minor planets as well as detection of previously known objects. However, many more asteroids are potentially recoverable in the NEOWISE data, such as objects that failed to appear in five or more images. Stacking of objects with well-known ephemerides at the observational epoch has allowed for the recovery of many objects that fell below the single-frame detection threshold. Additional objects were recovered by searching the NEOWISE source lists for objects that appeared fewer than five times in single frames. We present the results of a pilot study that has allowed for the recovery of minor planets from the NEOWISE data using both techniques, resulting in the derivation of diameters and albedos for the sample. This pilot study will be extended to the entire catalog of known minor planets by the NEOWISE project in the near future.

  14. Animation: A Binary and Its Planets

    NASA Video Gallery

    This artist's movie illustrates Kepler-47, the first transiting circumbinary system -- a system with more than one planet orbiting a pair of stars -- 4,900 light-years from Earth, in the constellat...

  15. Formation and Evolution of Planets in and Around Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Haghighipour, N.

    2015-07-01

    The discovery of planets in and around binary stars (also known as circumprimary and circumbinary planets) has opened a new chapter in the studies of the formation and dynamical evolution of planetary systems. Computational simulations indicate that in binaries with separations smaller than ˜50 au, the perturbation of the secondary star can have profound effects on the dynamics of solid bodies around the primary, prohibiting their collisions to result in coalescence and growth to larger objects. However, several circumprimary planets are known to exist in binaries with separations of ˜20 au raising questions about how these planets formed and acquired their final orbital architecture. Also, a survey of the currently known circumbinary planets (CBPs) points to several interesting characteristics of these bodies. The detection of multiple transits in these systems points to the (almost) co-planarity of the planet-binary orbits, giving strong support to the idea that these planets formed in circumbinary protoplanetary disks. The proximity of some of these planets to the boundary of orbital instability around the binary suggests an evolutionary scenario in which planets form at large distances and either migrate to their present orbits, or are scattered to their current locations. Surprisingly, all currently known CBPs are Neptune-sized or smaller, and no CBP seems to exist around very short-period binaries. These specific characteristics of binary-planetary systems have raised many questions regarding the formation, dynamical evolution, and orbital architecture of these objects. I will review the current state of research on the formation of planets in and around binary stars, and discuss the new developments on the understanding of their dynamical evolution.

  16. On possible circumbinary configurations of the planetary systems of α Centauri and EZ Aquarii

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Shevchenko, I. I.

    2016-04-01

    Possible configurations of the planetary systems of the binary stars α Cen A-BandEZAqr A-C are analyzed. The P-type orbits—circumbinary ones, i.e., the orbits around both stars of the binary, are studied. The choice of these systems is dictated by the fact that α Cen is closest to us in the Galaxy, while EZ Aqr is the closest system whose circumbinary planets, as it turns out, may reside in the "habitability zone." The analysis has been performed within the framework of the planar restricted three-body problem. The stability diagrams of circumbinary motion have been constructed: on representative sets of initial data (in the pericentric distance-eccentricity plane), we have computed the Lyapunov spectra of planetary motion and identified the domains of regular and chaotic motion through their statistical analysis. Based on present views of the dynamics and architecture of circumbinary planetary systems, we have determined the most probable planetary orbits to be at the centers of the main resonance cells, at the boundary of the dynamical chaos domain around the parent binary star, which allows the semimajor axes of the orbits to be predicted. In the case of EZ Aqr, the orbit of the circumbinary planet is near the habitability zone and, given that the boundary of this zone is uncertain, may belong to it.

  17. DETECTING OCEANS ON EXTRASOLAR PLANETS USING THE GLINT EFFECT

    SciTech Connect

    Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David

    2010-09-20

    Glint, the specular reflection of sunlight off Earth's oceans, may reveal the presence of oceans on an extrasolar planet. As an Earth-like planet nears crescent phases, the size of the ocean glint spot increases relative to the fraction of the illuminated disk, while the reflectivity of this spot increases. Both effects change the planet's visible reflectivity as a function of phase. However, strong forward scattering of radiation by clouds can also produce increases in a planet's reflectivity as it approaches crescent phases, and surface glint can be obscured by Rayleigh scattering and atmospheric absorption. Here, we explore the detectability of glint in the presence of an atmosphere and realistic phase-dependent scattering from oceans and clouds. We use the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model to simulate Earth's broadband visible brightness and reflectivity over an orbit. Our validated simulations successfully reproduce phase-dependent Earthshine observations. We find that the glinting Earth can be as much as 100% brighter at crescent phases than simulations that do not include glint, and that the effect is dependent on both orbital inclination and wavelength, where the latter dependence is caused by Rayleigh scattering limiting sensitivity to the surface. We show that this phenomenon may be observable using the James Webb Space Telescope paired with an external occulter.

  18. HABITABLE PLANETS ECLIPSING BROWN DWARFS: STRATEGIES FOR DETECTION AND CHARACTERIZATION

    SciTech Connect

    Belu, Adrian R.; Selsis, Franck; Raymond, Sean N.; Bolmont, Emeline; Palle, Enric; Street, Rachel; Sahu, D. K.; Anupama, G. C.; Von Braun, Kaspar; Figueira, Pedro; Ribas, Ignasi

    2013-05-10

    Given the very close proximity of their habitable zones, brown dwarfs (BDs) represent high-value targets in the search for nearby transiting habitable planets that may be suitable for follow-up occultation spectroscopy. In this paper, we develop search strategies to find habitable planets transiting BDs depending on their maximum habitable orbital period (P{sub HZ{sub out}}). Habitable planets with P{sub HZ{sub out}} shorter than the useful duration of a night (e.g., 8-10 hr) can be screened with 100% completeness from a single location and in a single night (near-IR). More luminous BDs require continuous monitoring for longer duration, e.g., from space or from a longitude-distributed network (one test scheduling achieved three telescopes, 13.5 contiguous hours). Using a simulated survey of the 21 closest known BDs (within 7 pc) we find that the probability of detecting at least one transiting habitable planet is between 4.5{sup +5.6}{sub -1.4}% and 56{sup +31}{sub -13}%, depending on our assumptions. We calculate that BDs within 5-10 pc are characterizable for potential biosignatures with a 6.5 m space telescope using {approx}1% of a five-year mission's lifetime spread over a contiguous segment only one-fifth to one-tenth of this duration.

  19. Radial Velocity Planet Detection Biases at the Stellar Rotational Period

    NASA Astrophysics Data System (ADS)

    Vanderburg, Andrew; Plavchan, Peter; Asher Johnson, John; Ciardi, David R.; Swift, Jonathan; Kane, Stephen R.

    2016-04-01

    Future generations of precise radial velocity (RV) surveys aim to achieve sensitivity sufficient to detect Earth mass planets orbiting in their stars' habitable zones. A major obstacle to this goal is astrophysical radial velocity noise caused by active areas moving across the stellar limb as a star rotates. In this paper, we quantify how stellar activity impacts exoplanet detection with radial velocities as a function of orbital and stellar rotational periods. We perform data-driven simulations of how stellar rotation affects planet detectability and compile and present relations for the typical timescale and amplitude of stellar radial velocity noise as a function of stellar mass. We show that the characteristic timescales of quasi-periodic radial velocity jitter from stellar rotational modulations coincides with the orbital period of habitable zone exoplanets around early M-dwarfs. These coincident periods underscore the importance of monitoring the targets of RV habitable zone planet surveys through simultaneous photometric measurements for determining rotation periods and activity signals, and mitigating activity signals using spectroscopic indicators and/or RV measurements at different wavelengths.

  20. Radial velocity planet detection biases at the stellar rotational period

    NASA Astrophysics Data System (ADS)

    Vanderburg, Andrew; Plavchan, Peter; Johnson, John Asher; Ciardi, David R.; Swift, Jonathan; Kane, Stephen R.

    2016-07-01

    Future generations of precise radial velocity (RV) surveys aim to achieve sensitivity sufficient to detect Earth mass planets orbiting in their stars' habitable zones. A major obstacle to this goal is astrophysical RV noise caused by active areas moving across the stellar limb as a star rotates. In this paper, we quantify how stellar activity impacts exoplanet detection with radial velocities as a function of orbital and stellar rotational periods. We perform data-driven simulations of how stellar rotation affects planet detectability and compile and present relations for the typical time-scale and amplitude of stellar RV noise as a function of stellar mass. We show that the characteristic time-scales of quasi-periodic RV jitter from stellar rotational modulations coincides with the orbital period of habitable-zone exoplanets around early M-dwarfs. These coincident periods underscore the importance of monitoring the targets of RV habitable-zone planet surveys through simultaneous photometric measurements for determining rotation periods and activity signals, and mitigating activity signals using spectroscopic indicators and/or RV measurements at different wavelengths.

  1. ''High-Speed, Photon-Counting Camera for the Detection of Extrasolar Planets''

    SciTech Connect

    Ullom, J; Cunningham, M; Macintosh, B; Miyazaki, T; Labov, S

    2003-02-07

    The search for extrasolar planets--planets orbiting stars outside out solar system-- is motivated by the desire to discover small planets similar to Earth. Since small planets are difficult to detect, the first step is finding giant planets with large orbits, like Jupiter. Solar systems containing these planets may have smaller, Earth-like planets travelling closer to the parent star. However, current methods detect extrasolar planets indirectly by observing a planet's gravitational influence on its parent star. These methods are primarily sensitive to giant planets with small orbits. A new method is needed to directly observe planets with large orbits. Direct observation can also provide additional information about a planet's composition and/or orbit. Directly observing an extrasolar planet from Earth is challenging because of the relative proximity of the planet to its parent star. Although a large, terrestrial telescope can provide the angular resolution necessary to visually separate the planet from the star, atmospheric turbulence limits the telescope's performance. In addition, the parent star appears much brighter than the planet. Adaptive optics (AO) can increase a planet's brightness, but they have little effect on residual star glare.

  2. The use of transit timing to detect terrestrial-mass extrasolar planets.

    PubMed

    Holman, Matthew J; Murray, Norman W

    2005-02-25

    Future surveys for transiting extrasolar planets are expected to detect hundreds of jovian-mass planets and tens of terrestrial-mass planets. For many of these newly discovered planets, the intervals between successive transits will be measured with an accuracy of 0.1 to 100 minutes. We show that these timing measurements will allow for the detection of additional planets in the system (not necessarily transiting) by their gravitational interaction with the transiting planet. The transit-time variations depend on the mass of the additional planet, and in some cases terrestrial-mass planets will produce a measurable effect. In systems where two planets are seen to transit, the density of both planets can be determined without radial-velocity observations. PMID:15731449

  3. ON THE DETECTABILITY OF STAR-PLANET INTERACTION

    SciTech Connect

    Miller, Brendan P.; Gallo, Elena; Wright, Jason T.; Dupree, Andrea K.

    2012-08-01

    Magnetic (or tidal) interactions between 'hot Jupiters' and their host stars can potentially enhance chromospheric and coronal activity. An ideal test bed for investigating this effect is provided by the extreme WASP-18 system, which features a massive ({approx}10 times Jupiter) close-in ({approx}<1 day period) transiting planet orbiting a young F6 star. Optical and X-ray observations of WASP-18 were conducted in 2011 November. The high-resolution echelle spectrograph Magellan Inamori Kyocera Echelle was used on the 6.5 m Magellan Clay Telescope to obtain 13 spectra spanning planetary orbital phases of 0.7-1.4, while the X-ray Telescope on Swift provided contemporaneous monitoring with a stacked exposure of {approx}50 ks. The cores of the Ca II H and K lines do not show significant variability over multiple orbits spanning {approx}8 days, in contrast to the expectation of phase-dependent chromospheric activity enhancements for efficient star-planet interaction. The star is also X-ray faint, with log L{sub X} < 27.6, indicating that coronal activity is likewise low. The lack of detectable star-planet interaction in this extreme system requires that any such effect here must be transient, if indeed present. We demonstrate that searches for Ca II H and K variability can potentially mistake a stellar hotspot, if observed over a short segment of the rotation period, for planet-induced activity. Taken together, these results suggest that the utility of star-planet interaction as a robust method of estimating exoplanet magnetic field strengths may be limited.

  4. ICE LINES IN CIRCUMBINARY PROTOPLANETARY DISKS

    SciTech Connect

    Clanton, Christian

    2013-05-01

    I examine the position of the ice line in circumbinary disks heated by steady mass accretion and stellar irradiation and compare with the critical semimajor axis, interior to which planetary orbits are unstable. There is a critical binary separation, dependent on the binary parameters and disk properties, for which binaries with separations larger than this critical value have ice lines that lie interior to the boundary of stability. For an equal-mass binary comprised of 1 M{sub Sun} components, this critical separation is Almost-Equal-To 1.04 AU, and scales weakly with mass accretion rate and Rosseland mean opacity ({proportional_to}[ M-dot {kappa}{sub R}]{sup 2/9}). Assuming a steady mass accretion rate of M-dot {approx}10{sup -8} M{sub Sun} yr{sup -1} and a Rosseland mean opacity of {kappa}{sub R} {approx} 1 cm{sup 2} g{sup -1}, I show that {approx}> 80% of all binary systems with component masses M{sub *} {approx}< 2.0 M{sub Sun} have ice lines that lie interior to the critical semimajor axis. This suggests that rocky planets should not form in these systems, a prediction which can be tested by looking for planets around binaries with separations larger than the critical separation with Kepler (difficult) and with microlensing.

  5. The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Marley, Mark S.; Laughlin, Gregory; Nettelmann, Nadine; Morley, Caroline V.; Lupu, Roxana E.; Visscher, Channon; Jeremic, Pavle; Khadder, Wade G.; Hargrave, Mason

    2016-06-01

    We investigate the physical characteristics of the solar system’s proposed Planet Nine using modeling tools with a heritage of studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic {T}{{eff}}, from ∼35 to 50 K for masses of 5–20 M ⊕, and we also explore lower {T}{{eff}} values. Possible planetary radii could readily span from 2.7 to 6 R ⊕, depending on the mass fraction of any H/He envelope. Given its cold atmospheric temperatures, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like expectations. We find that the atmosphere is strongly depleted in molecular absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere with a high geometric albedo approaching 0.75. We highlight two diagnostics for the atmosphere’s temperature structure: (1) the value of the methane mixing ratio above the methane cloud and (2) the wavelength at which cloud scattering can be seen, which yields the cloud-top pressure. Surface reflection may be seen if the atmosphere is thin. Due to collision-induced opacity of H2 in the infrared, the planet would be extremely blue instead of red in the shortest wavelength WISE colors if methane is depleted and would, in some cases, exist on the verge of detectability by WISE. For a range of models, thermal fluxes from ∼3 to 5 μm are ∼20 orders of magnitude larger than blackbody expectations. We report a search of the AllWISE Source Catalog for Planet Nine, but find no detection.

  6. The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Marley, Mark S.; Laughlin, Gregory; Nettelmann, Nadine; Morley, Caroline V.; Lupu, Roxana E.; Visscher, Channon; Jeremic, Pavle; Khadder, Wade G.; Hargrave, Mason

    2016-06-01

    We investigate the physical characteristics of the solar system’s proposed Planet Nine using modeling tools with a heritage of studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic {T}{{eff}}, from ˜35 to 50 K for masses of 5–20 M ⊕, and we also explore lower {T}{{eff}} values. Possible planetary radii could readily span from 2.7 to 6 R ⊕, depending on the mass fraction of any H/He envelope. Given its cold atmospheric temperatures, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like expectations. We find that the atmosphere is strongly depleted in molecular absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere with a high geometric albedo approaching 0.75. We highlight two diagnostics for the atmosphere’s temperature structure: (1) the value of the methane mixing ratio above the methane cloud and (2) the wavelength at which cloud scattering can be seen, which yields the cloud-top pressure. Surface reflection may be seen if the atmosphere is thin. Due to collision-induced opacity of H2 in the infrared, the planet would be extremely blue instead of red in the shortest wavelength WISE colors if methane is depleted and would, in some cases, exist on the verge of detectability by WISE. For a range of models, thermal fluxes from ˜3 to 5 μm are ˜20 orders of magnitude larger than blackbody expectations. We report a search of the AllWISE Source Catalog for Planet Nine, but find no detection.

  7. TPF Planet Detection Testbed: demonstrating deep, stable nulling and planet detection

    NASA Technical Reports Server (NTRS)

    Martin, Stefan

    2005-01-01

    The design of a testbed being built at the Jet Propulsion Laboratory is described. Simulatiung a dual chopped Bracewell interferometer, the testbed comprises a four beam star and planet source and nulling beam combiner. Since achieving a stable null is of great concern the testbed has many control systems designed to achieve stability of alignment and optical path difference over long periods of time. Comparisons between the testbed and the flight system are drawn and key performance parameters are discussed. The interaction between designs for phaseplate systems that achromatically invert the electric field of one of each pair of the incoming beams to achieve the null and the choice of fringe tracking schemes is also discussed.

  8. Toward a Model for Detecting Life on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Rye, R.; Storrie-Lombardi, M.

    2001-12-01

    available energy sources may be used by biology on detectably colonized planets. Simple feedback loops such as those governing Lovelock?s famous Daisyworld or the Walker CO2 feedback, offer starting points for thinking about global scale feedbacks. Feedbacks in microbial communities, e.g. those postulated in anaerobic methane oxidation communities, involving the use of one or more organisms? waste products as nutrients by another, hint at the local complexity from which we need to scale up. Our first attempt at bridging this gap involves describing the processes that may have helped stabilize the Archean climate. Archean biogenic methane production could have been rapid enough to provide 100s ppm atmospheric CH4. At such CH4 levels Earth would have remained ice free. Sudden increases in CH4 production might have led to runaway greenhouse conditions. However, if CH4/CO2 > 1 a UV absorbing aerosol haze should form. UV-labile ammonia could have accumulated in the atmosphere under the haze, quickly making rain pH > 7, dramatically slowing chemical weathering on the continents and interrupting vital phosphate delivery to the oceans. The residence time of P is ca.10,000 years. Thus, over a time scale of ca.10,000 years primary productivity dropped sharply. Biogenic methane production, near the base of the trophic ladder, suffered disproportionately. With little CH4 production CH4/CO2 fell to < 1. The UV screen and atmospheric NH3 disappeared in a few years. Rain pH dropped. Weathering restarted. Biological productivity recovered. The above testable scenario serves as an example of a plausible feedback involving interplay between biological, geochemical, atmospheric and stellar processes. Feedback loops of this sort will be central features of the fully realized VMC module for the VPL.

  9. White-Light Nulling Interferometers for Detecting Planets

    NASA Technical Reports Server (NTRS)

    Mennesson, Bertrand; Serabyn, Eugene; Shao, Michael; Levine, Bruce

    2004-01-01

    A report proposes the development of a white-light nulling interferometer to be used in conjunction with a singleaperture astronomical telescope that would be operated in outer space. When such a telescope is aimed at a given star, the interferometer would suppress the light of that star while passing enough light from planets (if any) orbiting the star, to enable imaging or spectroscopic examination of the planets. In a nulling interferometer, according to the proposal, scattered light would be suppressed by spatial filtering in an array of single-mode optical fibers rather than by requiring optical surfaces to be accurate within 1/4,000 wavelength as in a coronagraph or an apodized telescope. As a result, angstrom-level precision would be needed in only the small nulling combiner, and not in large, meter-sized optics. The nulling interferometer could work as an independent instrument in space or in conjunction with a coronagraphic system to detect planets outside our solar system.

  10. An Infrared Telescope for Planet Detection and General Astrophysics

    NASA Technical Reports Server (NTRS)

    Lillie, C. F.; Atkinson, C. B.; Casement, L. S.; Flannery, M. R.; Kroening, K. V.; Moses, S. L.

    2004-01-01

    NASA plans to launch a Terrestrial Planet Finder (TPF) mission in 2014 to detect and characterize Earth-like planets around nearby stars, perform comparative planetology studies, and obtain general astrophysics observations. During our recently completed a TPF Mission Architecture study for NASA/JPL we developed the conceptual design for a 28-meter telescope with an IR Coronagraph that meets these mission objectives. This telescope and the technology it embodies are directly applicable to future Far-IR and Submillimeter space missions. The detection of a 30th magnitude planet located within 50 milli-arc-seconds of a 5th (Visual) magnitude star is an exceptionally challenging objective. Observations in the thermal infrared (7-17 microns) are somewhat easier since the planet is "only" 15(sup m) fainter than the star at these wavelengths, but many severe challenges must still be overcome. These challenges include: 1. Designing a coronagraph for star:planet separations less than or equal to lambda/D. 2. Developing the deployment scheme for a 28m space telescope that can fit in an existing launch vehicle payload fairing. 3. Generating configuration layouts for the IR telescope, coronagraph, spacecraft bus, sunshade, solar array, and high-gain antenna. 4. Providing: Structural stability to within 10 microns to support the optics. Thermal control to achieve the necessary structural stability, as well as providing a stable (approx. 30K) thermal environment for the optics. Dynamics isolation from potential jitter sources. 5. Minimizing launch mass to provide the maximum payload for the science mission Interfacing to an EELV Heavy launch vehicle, including acoustic and stress loads for the launch environment. 6. Identifying the key technologies (which can be developed by 2009) that will enable TPF mission to be performed. 7. Generating a manufacturing plan that will permit TPF to be developed at a reasonable cost and schedule. Many of these design challenges result in

  11. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    NASA Astrophysics Data System (ADS)

    1996-01-01

    Do nearby stars have planetary systems like our own? How do such systems evolve? How common are such systems? Proposed radio observatories operating at millimeter wavelengths could start answering these questions within the next 6-10 years, according to scientists at the National Radio Astronomy Observatory (NRAO). Bryan Butler, Robert Brown, Richard Simon, Al Wootten and Darrel Emerson, all of NRAO, presented their findings today to the American Astronomical Society meeting in San Antonio, TX. Detecting planets circling other stars is a particularly difficult task, and only a few such planets have been discovered so far. In order to answer fundamental questions about planetary systems and their origin, scientists need to find and study many more extrasolar planets. According to the NRAO scientists, millimeter-wavelength observatories could provide valuable information about extrasolar planetary systems at all stages of their evolution. "With instruments planned by 2005, we could detect planets the size of Jupiter around a solar-type star out to a distance of 100 light-years," said Robert Brown, Associate Director of NRAO. "That means," he added, "that we could survey approximately 2,000 stars of different types to learn if they have planets this size." Millimeter waves occupy the portion of the electromagnetic spectrum between radio microwaves and infrared waves. Telescopes for observing at millimeter wavelengths utilize advanced electronic equipment similar to that used in radio telescopes observing at longer wavelengths. Millimeter-wave observatories offer a number of advantages in the search for extrasolar planets. Planned multi-antenna millimeter-wave telescopes can provide much higher resolving power, or ability to see fine detail, than current optical or infrared telescopes. Millimeter-wave observations would not be degraded by interference from the "zodiacal light" reflected by interplanetary dust, either in the extrasolar system or our own solar system

  12. Fabrication experiments on supersmooth optics for extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Ftaclas, C.; Krim, M. H.; Terrile, R. J.

    1989-01-01

    The direct detection of extrasolar planets by imaging will require reductions in scattered and diffracted light by factors in excess of 1000 within one arcsecond of a bright source. While diffraction can be reduced by a number of approaches, small angle scatter can only be reduced by controlling midspatial frequency figure errors. The surface requirements are reviewed and their meaning when compared to the data base of existing mirrors is considered. Experiments are discribed that were successful in reducing midspatial frequency figure so that the scatter level was 500 times less than diffraction for a 25-cm spherical mirror.

  13. Kepler Planet Detection Mission: Introduction and First Results

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Lissauer, Jack J.; Morrison, David; Rowe, Jason; Bryson, Stephen T.; Dotson, Jessie; Haas,Michael; Gautier, Thomas N.

    2010-01-01

    The Kepler Mission is designed to determine the frequency of Earth-size and rocky planets in and near the habitable zone (HZ) of solar-like stars. The HZ is defined to be the region of space where a rocky planet could maintain liquid water on its surface. Kepler is the 10th competitively-selected Discovery Mission and was launched on March 6, 2009. Since completing its commissioning, Kepler has observed over 156,000 stars simultaneously and near continuously to search for planets that periodically pass in front of their host star (transit). The photometric precision is approximately 23 ppm for 50% of the 12th magnitude dwarf stars for an integration period of 6.5 hours. During the first 3 months of operation the photometer detected transit-like signatures from more than 200 stars. Careful examination shows that many of these events are false-positives such as small stars orbiting large stars or blends of target stars with eclipsing binary stars. Ground-based follow-up observations confirm the discovery of five new exoplanets with sizes between 0.37 andl.6 Jupiter radii (R(sub J)) and orbital periods ranging from 3.2 to 4.9 days. Ground-based observations with the Keck 1, Hobby-Ebberly, Hale, WIYN, MMT, Tillinghast, Shane, and Nordic Optical Telescopes are used to vet the planetary candidates and measure the masses of the putative planets. Observations of occultations and phase variations of hot, short-period planets such as HT-P-7b provide a probe of atmospheric properties. Asteroseismic analysis already shows the presence of p-mode oscillations in several stars. Such observations will be used to measure the mean stellar density and infer the stellar size and age. For stars too dim to permit asteroseismology, observations of the centroid motion of target stars will be used to measure the parallax and be combined with photometric measurements to estimate stellar sizes. Four open clusters are being observed to determine stellar rotation rates as a function of age and

  14. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Mogavero, F.; Beaulieu, J. P.

    2016-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE ≈ 20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE ≈ 1 day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, tE ≈ 0.1 days. A Fisher matrix analysis is employed to predict how the 1-σ error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

  15. Transiting planets with LSST. I. Potential for LSST exoplanet detection

    SciTech Connect

    Lund, Michael B.; Pepper, Joshua; Stassun, Keivan G.

    2015-01-01

    The Large Synoptic Survey Telescope (LSST) is designed to meet several scientific objectives over a 10 year synoptic sky survey. Beyond its primary goals, the large amount of LSST data can be exploited for additional scientific purposes. We show that LSST data are sufficient to detect the transits of exoplanets, including planets orbiting stars that are members of stellar populations that have so far been largely unexplored. Using simulated LSST light curves, we find that existing transit detection algorithms can identify the signatures of Hot Jupiters around solar-type stars, Hot Neptunes around K-dwarfs, and (in favorable cases) Super-Earths in habitable-zone orbits of M-dwarfs. We also find that LSST may identify Hot Jupiters orbiting stars in the Large Magellanic Cloud—a remarkable possibility that would advance exoplanet science into the extragalactic regime.

  16. Kepler-47: a transiting circumbinary multiplanet system.

    PubMed

    Orosz, Jerome A; Welsh, William F; Carter, Joshua A; Fabrycky, Daniel C; Cochran, William D; Endl, Michael; Ford, Eric B; Haghighipour, Nader; MacQueen, Phillip J; Mazeh, Tsevi; Sanchis-Ojeda, Roberto; Short, Donald R; Torres, Guillermo; Agol, Eric; Buchhave, Lars A; Doyle, Laurance R; Isaacson, Howard; Lissauer, Jack J; Marcy, Geoffrey W; Shporer, Avi; Windmiller, Gur; Barclay, Thomas; Boss, Alan P; Clarke, Bruce D; Fortney, Jonathan; Geary, John C; Holman, Matthew J; Huber, Daniel; Jenkins, Jon M; Kinemuchi, Karen; Kruse, Ethan; Ragozzine, Darin; Sasselov, Dimitar; Still, Martin; Tenenbaum, Peter; Uddin, Kamal; Winn, Joshua N; Koch, David G; Borucki, William J

    2012-09-21

    We report the detection of Kepler-47, a system consisting of two planets orbiting around an eclipsing pair of stars. The inner and outer planets have radii 3.0 and 4.6 times that of Earth, respectively. The binary star consists of a Sun-like star and a companion roughly one-third its size, orbiting each other every 7.45 days. With an orbital period of 49.5 days, 18 transits of the inner planet have been observed, allowing a detailed characterization of its orbit and those of the stars. The outer planet's orbital period is 303.2 days, and although the planet is not Earth-like, it resides within the classical "habitable zone," where liquid water could exist on an Earth-like planet. With its two known planets, Kepler-47 establishes that close binary stars can host complete planetary systems. PMID:22933522

  17. The Automated Planet Finder's detection of a 6-planet system orbiting the bright, nearby star HD219134

    NASA Astrophysics Data System (ADS)

    Burt, Jennifer; Laughlin, Greg; Meschiari, Stefano; Vogt, Steve; Butler, R. Paul

    2015-12-01

    The Automated Planet Finder (APF) is the newest facility at Lick Observatory, comprised of a 2.4m telescope coupled with the high-resolution Levy echelle spectrograph. Purpose built for exoplanet detection and characterization, 80% of the telescope's observing time is dedicated to these science goals. The APF has demonstrated 1 m/s radial velocity precision on bright, RV standard stars and performs with the same speed-on-sky as Keck/HIRES when observing M-dwarfs.The APF has contributed to the detection of four planetary systems in its first two years of scientific operations. Our most recent detection is that of a 6-planet system around the bright (V=5.5), nearby (d=6.5pc), K3V star HD219134. The planets in this system have masses ranging from 3.5 to108 MEarth, with orbital periods from 3 to 2247 days. An independent detection of the inner 4 planets in this system by the HARPS-N team has shown that the 3d planet transits the star, making this system ideal for follow-up observations.I will discuss the APF's detections to date, highlighting HD219134, as well as the overall performance results of the telescope and our future observing strategy.

  18. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    NASA Astrophysics Data System (ADS)

    1996-01-01

    Do nearby stars have planetary systems like our own? How do such systems evolve? How common are such systems? Proposed radio observatories operating at millimeter wavelengths could start answering these questions within the next 6-10 years, according to scientists at the National Radio Astronomy Observatory (NRAO). Bryan Butler, Robert Brown, Richard Simon, Al Wootten and Darrel Emerson, all of NRAO, presented their findings today to the American Astronomical Society meeting in San Antonio, TX. Detecting planets circling other stars is a particularly difficult task, and only a few such planets have been discovered so far. In order to answer fundamental questions about planetary systems and their origin, scientists need to find and study many more extrasolar planets. According to the NRAO scientists, millimeter-wavelength observatories could provide valuable information about extrasolar planetary systems at all stages of their evolution. "With instruments planned by 2005, we could detect planets the size of Jupiter around a solar-type star out to a distance of 100 light-years," said Robert Brown, Associate Director of NRAO. "That means," he added, "that we could survey approximately 2,000 stars of different types to learn if they have planets this size." Millimeter waves occupy the portion of the electromagnetic spectrum between radio microwaves and infrared waves. Telescopes for observing at millimeter wavelengths utilize advanced electronic equipment similar to that used in radio telescopes observing at longer wavelengths. Millimeter-wave observatories offer a number of advantages in the search for extrasolar planets. Planned multi-antenna millimeter-wave telescopes can provide much higher resolving power, or ability to see fine detail, than current optical or infrared telescopes. Millimeter-wave observations would not be degraded by interference from the "zodiacal light" reflected by interplanetary dust, either in the extrasolar system or our own solar system

  19. Super Smooth Optics for Extra-Solar Planet Detection

    NASA Technical Reports Server (NTRS)

    Terrile, Richard J.; Ftaclas, Christ

    1989-01-01

    The goal of imaging planets around the nearby stars has important scientific significance but requires the use of advanced methods of controlling diffracted and scattered light. Over the last three years we have undertaken a study of coronagraphic methods of controlling diffracted light and of figuring hyper-contrast optics. Progress in these two general areas have led to a proposed space-based, 1.9 meter diameter coronagraphic telescope designed specifically for very high performance in the imaging of faint objects near bright sources. This instrument, called the Circumstellar Imaging Telescope (CIT), relies on a new high efficiency coronagraph design and the careful control of scattered light by extremely smooth optics. The high efficiency coronagraph uses focal plane apodization in order to concentrate diffracted light more efficiently in the pupil. This allows convenient removal of the diffracted light by masking off parts of the telescope pupil while not sacrificing the center of the field. Reductions of diffracted light by factors exceeding 1000 are not only possible but are required in order to detect extra-solar planets. Laboratory experiments with this new design have confirmed the theoretical diffraction reductions to the limits of the optics used (factors of about 300) . The extremely high efficiency of this coronagraph puts strong constraints on the narrow angle scattered light due to figure errors in the telescope mirror. Since planets orbiting nearby stars are expected at angular distances of about 1 arcsecond, it is in this small angular range in which scattering must be controlled. The figure errors responsible for scattering in this range come from mid-spatial frequencies corresponding to correlation lengths of about 10 cm on the primary mirror. A primary mirror about 15 times smoother than the Hubble Space Telescope mirror is required for the CIT. Laboratory experiments indicate that small test mirrors can be fabricated with existing technology

  20. Planet Hunters: Kepler by Eye

    NASA Astrophysics Data System (ADS)

    Schwamb, Megan E.; Lintott, C.; Fischer, D.; Smith, A. M.; Boyajian, T. S.; Brewer, J. M.; Giguere, M. J.; Lynn, S.; Parrish, M.; Schawinski, K.; Schmitt, J.; Simpson, R.; Wang, J.

    2014-01-01

    Planet Hunters (http://www.planethunters.org), part of the Zooniverse's (http://www.zooniverse.org) collection of online citizen science projects, uses the World Wide Web to enlist the general public to identify transits in the pubic Kepler light curves. Planet Hunters utilizes human pattern recognition to identify planet transits that may be missed by automated detection algorithms looking for periodic events. Referred to as ‘crowdsourcing’ or ‘citizen science’, the combined assessment of many non-expert human classifiers with minimal training can often equal or best that of a trained expert and in many cases outperform the best machine-learning algorithm. Visitors to the Planet Hunters' website are presented with a randomly selected ~30-day light curve segment from one of Kepler’s ~160,000 target stars and are asked to draw boxes to mark the locations of visible transits in the web interface. 5-10 classifiers review each 30-day light curve segment. Since December 2010, more than 260,000 volunteers world wide have participated, contributing over 20 million classifications. We have demonstrated the success of a citizen science approach with the project’s more than 20 planet candidates, the discovery of PH1b, a transiting circumbinary planet in a quadruple star system, and the discovery of PH2-b, a confirmed Jupiter-sized planet in the habitable zone of a Sun-like star. I will provide an overview of Planet Hunters, highlighting several of project's most recent exoplanet and astrophysical discoveries. Acknowledgements: MES was supported in part by a NSF AAPF under award AST-1003258 and a American Philosophical Society Franklin Grant. We acknowledge support from NASA ADAP12-0172 grant to PI Fischer.

  1. THE HABITABILITY AND DETECTION OF EARTH-LIKE PLANETS ORBITING COOL WHITE DWARFS

    SciTech Connect

    Fossati, L.; Haswell, C. A.; Patel, M. R.; Busuttil, R.; Bagnulo, S.; Kowalski, P. M.; Shulyak, D. V.; Sterzik, M. F. E-mail: C.A.Haswell@open.ac.uk E-mail: r.busuttil@open.ac.uk E-mail: kowalski@gfz-potsdam.de E-mail: msterzik@eso.org

    2012-09-20

    Since there are several ways planets can survive the giant phase of the host star, we examine the habitability and detection of planets orbiting white dwarfs. As a white dwarf cools from 6000 K to 4000 K, a planet orbiting at 0.01 AU would remain in the continuous habitable zone (CHZ) for {approx}8 Gyr. We show that photosynthetic processes can be sustained on such planets. The DNA-weighted UV radiation dose for an Earth-like planet in the CHZ is less than the maxima encountered on Earth, and hence non-magnetic white dwarfs are compatible with the persistence of complex life. Polarization due to a terrestrial planet in the CHZ of a cool white dwarf (CWD) is 10{sup 2} (10{sup 4}) times larger than it would be in the habitable zone of a typical M-dwarf (Sun-like star). Polarimetry is thus a viable way to detect close-in rocky planets around white dwarfs. Multi-band polarimetry would also allow us to reveal the presence of a planet atmosphere, providing a first characterization. Planets in the CHZ of a 0.6 M{sub Sun} white dwarf will be distorted by Roche geometry, and a Kepler-11d analog would overfill its Roche lobe. With current facilities a super-Earth-sized atmosphereless planet is detectable with polarimetry around the brightest known CWD. Planned future facilities render smaller planets detectable, in particular by increasing the instrumental sensitivity in the blue.

  2. NASA's Kepler Mission Discovers Multiple Planets Orbiting Twin Suns

    NASA Video Gallery

    NASA's Kepler mission has discovered the first transiting circumbinary system -- multiple planets orbiting two suns -- 4,900 light-years from Earth, in the constellation Cygnus, proving that more t...

  3. Diagrams of stability of circumbinary planetary systems (Abstract)

    NASA Astrophysics Data System (ADS)

    Popova, E.

    2015-08-01

    The stability diagrams in the "pericentric distance - eccentricity" plane of initial data are built and analysed for Kepler-38, Kepler-47, and PH1. This completes a survey of stability of the known up to now circumbinary planetary systems, initiated by Popova and Shevchenko (ApJ, 769, 152, 2013), where the analysis was performed for Kepler-16, 34, and 35. In the diagrams, the planets appear to be "embedded" in the fractal chaos border; however, I make an attempt to measure the "distance" to the chaos border in a physically consistent way. The obtained distances are compared to those given by the widely used numerical-experimental criterion by Holman and Wiegert (1999), who employed smooth polynomial approximations to describe the border. I identify the resonance cells, hosting the planets. Results of this study will appear in Proceedings of IAU Symposium 310 "Complex planetary systems".

  4. Planet Scattering Around Binaries: Ejections, Not Collisions

    NASA Astrophysics Data System (ADS)

    Smullen, Rachel A.; Kratter, Kaitlin M.; Shannon, Andrew

    2016-06-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary star and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically effects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Systems similar to the only observed multi-planet circumbinary system, Kepler-47, can arise from much more tightly packed, unstable systems. Only extreme initial conditions introduce differences in the final planet populations. Thus, we suggest that any intrinsic differences in the populations are imprinted by formation.

  5. A path to the detection of Earth-type planets (Jean Dominique Cassini Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Mayor, Michel

    2016-04-01

    "How many planets in the Milky Way?", "How many planets similar to our Earth?" On the last twenty years, significant results have been obtained in the domain of extrasolar planets. More than two thousand planets have characterized orbits, for several hundred of them their radii are known. We have discovered an amazing diversity of planetary systems. These observations have revealed the importance of new physical process to be taken into account for the formation and evolution of planetary systems. The synergy between ground-based radial velocity measurements and the detection of transiting planets have permitted exciting possibilities to characterize planets. Already we have the possibility to get clues on the internal composition of exoplanets and their atmosphere. Do we have the instrumental capabilities to detect and study planets as Earth analogues? What are the intruments in development and their scientific goals.

  6. Planet scattering around binaries: ejections, not collisions

    NASA Astrophysics Data System (ADS)

    Smullen, Rachel A.; Kratter, Kaitlin M.; Shannon, Andrew

    2016-09-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary star and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically affects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Systems similar to the only observed multiplanet circumbinary system, Kepler-47, can arise from much more tightly packed, unstable systems. Only extreme initial conditions introduce differences in the final planet populations. Thus, we suggest that any intrinsic differences in the populations are imprinted by formation.

  7. Planetary atmosphere evolution: do other habitable planets exist and can we detect them?

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.

    1996-01-01

    The goal of this conference is to consider whether it is possible within the next few decades to detect Earth-like planets around other stars using telescopes or interferometers on the ground or in space. Implicit in the term "Earth-like" is the idea that such planets might be habitable by Earth-like organisms, or that they might actually be inhabited. Here, I shall address two questions from the standpoint of planetary atmosphere evolution. First, what are the chances that habitable planets exist around other stars? And, second, if inhabited planets exist, what would be the best way to detect them?.

  8. Doppler spectroscopy as a path to the detection of Earth-like planets.

    PubMed

    Mayor, Michel; Lovis, Christophe; Santos, Nuno C

    2014-09-18

    Doppler spectroscopy was the first technique used to reveal the existence of extrasolar planetary systems hosted by solar-type stars. Radial-velocity surveys led to the detection of a rich population of super-Earths and Neptune-type planets. The numerous detected systems revealed a remarkable diversity. Combining Doppler measurements with photometric observations of planets transiting their host stars further provides access to the planet bulk density, a first step towards comparative exoplanetology. The development of new high-precision spectrographs and space-based facilities will ultimately lead us to characterize rocky planets in the habitable zone of our close stellar neighbours. PMID:25230654

  9. Warped circumbinary disks in active galactic nuclei

    SciTech Connect

    Hayasaki, Kimitake; Sohn, Bong Won; Jung, Taehyun; Zhao, Guangyao; Okazaki, Atsuo T.; Naito, Tsuguya

    2014-07-20

    We study a warping instability of a geometrically thin, non-self-gravitating disk surrounding binary supermassive black holes on a circular orbit. Such a circumbinary disk is subject to not only tidal torques due to the binary gravitational potential but also radiative torques due to radiation emitted from an accretion disk around each black hole. We find that a circumbinary disk initially aligned with the binary orbital plane is unstable to radiation-driven warping beyond the marginally stable warping radius, which is sensitive to both the ratio of vertical to horizontal shear viscosities and the mass-to-energy conversion efficiency. As expected, the tidal torques give no contribution to the growth of warping modes but tend to align the circumbinary disk with the orbital plane. Since the tidal torques can suppress the warping modes in the inner part of circumbinary disk, the circumbinary disk starts to be warped at radii larger than the marginally stable warping radius. If the warping radius is of the order of 0.1 pc, a resultant semi-major axis is estimated to be of the order of 10{sup –2} pc to 10{sup –4} pc for 10{sup 7} M{sub ☉} black hole. We also discuss the possibility that the central objects of observed warped maser disks in active galactic nuclei are binary supermassive black holes with a triple disk: two accretion disks around the individual black holes and one circumbinary disk surrounding them.

  10. Warped Circumbinary Disks in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Hayasaki, Kimitake; Sohn, Bong Won; Okazaki, Atsuo T.; Jung, Taehyun; Zhao, Guangyao; Naito, Tsuguya

    2014-07-01

    We study a warping instability of a geometrically thin, non-self-gravitating disk surrounding binary supermassive black holes on a circular orbit. Such a circumbinary disk is subject to not only tidal torques due to the binary gravitational potential but also radiative torques due to radiation emitted from an accretion disk around each black hole. We find that a circumbinary disk initially aligned with the binary orbital plane is unstable to radiation-driven warping beyond the marginally stable warping radius, which is sensitive to both the ratio of vertical to horizontal shear viscosities and the mass-to-energy conversion efficiency. As expected, the tidal torques give no contribution to the growth of warping modes but tend to align the circumbinary disk with the orbital plane. Since the tidal torques can suppress the warping modes in the inner part of circumbinary disk, the circumbinary disk starts to be warped at radii larger than the marginally stable warping radius. If the warping radius is of the order of 0.1 pc, a resultant semi-major axis is estimated to be of the order of 10-2 pc to 10-4 pc for 107 M ⊙ black hole. We also discuss the possibility that the central objects of observed warped maser disks in active galactic nuclei are binary supermassive black holes with a triple disk: two accretion disks around the individual black holes and one circumbinary disk surrounding them.

  11. A high sensitivity polarimeter for the direct detection and characterization of extra-solar planets

    NASA Astrophysics Data System (ADS)

    Hough, James H.; Lucas, Philip W.; Bailey, Jeremy A.; Tamura, Motohide

    2003-02-01

    We are constructing a high sensitivity optical polarimeter capable of detecting fractional polarization levels below 10-6. The science goal is to directly detect extra-solar planets (ESP), in contrast to the indirect methods such as radial velocity measurements. The polarimeter will detect starlight scattered from the atmosphere of the planet as a polarisation signal thereby giving information on the planetary atmospheres. The radius of the planet and the planet temperature can be determined from the measured albedo. The position angle of polarisation will enable the mass of planets, detected through radial velocity measurements, to be determined without the uncertainty of the orbit inclination (Msini). The polarimeter has an essentially simple and classical design but is able to take advantage, inter alia, of modern detector technology.

  12. Influence of Stellar Multiplicity on Planet Formation. II. Planets are Less Common in Multiple-star Systems with Separations Smaller than 1500 AU

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Fischer, Debra A.; Xie, Ji-Wei; Ciardi, David R.

    2014-08-01

    Almost half of the stellar systems in the solar neighborhood are made up of multiple stars. In multiple-star systems, planet formation is under the dynamical influence of stellar companions, and the planet occurrence rate is expected to be different from that of single stars. There have been numerous studies on the planet occurrence rate of single star systems. However, to fully understand planet formation, the planet occurrence rate in multiple-star systems needs to be addressed. In this work, we infer the planet occurrence rate in multiple-star systems by measuring the stellar multiplicity rate for planet host stars. For a subsample of 56 Kepler planet host stars, we use adaptive optics (AO) imaging and the radial velocity (RV) technique to search for stellar companions. The combination of these two techniques results in high search completeness for stellar companions. We detect 59 visual stellar companions to 25 planet host stars with AO data. Three stellar companions are within 2'' and 27 within 6''. We also detect two possible stellar companions (KOI 5 and KOI 69) showing long-term RV acceleration. After correcting for a bias against planet detection in multiple-star systems due to flux contamination, we find that planet formation is suppressed in multiple-star systems with separations smaller than 1500 AU. Specifically, we find that compared to single star systems, planets in multiple-star systems occur 4.5 ± 3.2, 2.6 ± 1.0, and 1.7 ± 0.5 times less frequently when a stellar companion is present at a distance of 10, 100, and 1000 AU, respectively. This conclusion applies only to circumstellar planets; the planet occurrence rate for circumbinary planets requires further investigation.

  13. Influence of stellar multiplicity on planet formation. II. Planets are less common in multiple-star systems with separations smaller than 1500 AU

    SciTech Connect

    Wang, Ji; Fischer, Debra A.; Xie, Ji-Wei; Ciardi, David R.

    2014-08-20

    Almost half of the stellar systems in the solar neighborhood are made up of multiple stars. In multiple-star systems, planet formation is under the dynamical influence of stellar companions, and the planet occurrence rate is expected to be different from that of single stars. There have been numerous studies on the planet occurrence rate of single star systems. However, to fully understand planet formation, the planet occurrence rate in multiple-star systems needs to be addressed. In this work, we infer the planet occurrence rate in multiple-star systems by measuring the stellar multiplicity rate for planet host stars. For a subsample of 56 Kepler planet host stars, we use adaptive optics (AO) imaging and the radial velocity (RV) technique to search for stellar companions. The combination of these two techniques results in high search completeness for stellar companions. We detect 59 visual stellar companions to 25 planet host stars with AO data. Three stellar companions are within 2'' and 27 within 6''. We also detect two possible stellar companions (KOI 5 and KOI 69) showing long-term RV acceleration. After correcting for a bias against planet detection in multiple-star systems due to flux contamination, we find that planet formation is suppressed in multiple-star systems with separations smaller than 1500 AU. Specifically, we find that compared to single star systems, planets in multiple-star systems occur 4.5 ± 3.2, 2.6 ± 1.0, and 1.7 ± 0.5 times less frequently when a stellar companion is present at a distance of 10, 100, and 1000 AU, respectively. This conclusion applies only to circumstellar planets; the planet occurrence rate for circumbinary planets requires further investigation.

  14. Reevaluating the feasibility of ground-based Earth-mass microlensing planet detections

    SciTech Connect

    Jung, Youn Kil; Park, Hyuk; Han, Cheongho; Hwang, Kyu-Ha; Shin, In-Gu; Choi, Joon-Young

    2014-05-10

    An important strength of the microlensing method to detect extrasolar planets is its high sensitivity to low-mass planets. However, many believe that microlensing detections of Earth-mass planets from ground-based observation would be difficult because of limits set by finite-source effects. This view comes from the previous estimation of planet detection probability based on the fractional deviation of planetary signals; however, a proper probability estimation is required when considering the source brightness, which is directly related to the photometric precision. In this paper, we reevaluate the feasibility of low-mass planet detections by considering photometric precision for different populations of source stars. From this, we find that the contribution of improved photometric precision to the planetary signal of a giant-source event is large enough to compensate for the decrease in magnification excess caused by finite-source effects. As a result, we conclude that giant-source events are suitable targets for Earth-mass planet detections with significantly higher detection probability than events involved with source stars of smaller radii, and we predict that Earth-mass planets could be detected by prospective high-cadence surveys.

  15. Viability and Detectability of Photosynthesis on Earth-like Planets

    NASA Astrophysics Data System (ADS)

    Wolstencroft, Ramon; Raven, John

    Based on current understanding of how photosynthesis arose and developed on Earth,we consider what factors would limit or encourage the viability of photosynthetically energized organisms on Earth-like planets (ELP's) orbiting nearby ms stars with a range of surface temperature. Assuming that the ELP originally had an atmosphere similar to that of the early Earth and orbited within the parent star's habitable zone ,the main factors are: (1) an adequate photon flux incident on the organism in the photosynthetically active region (400 to 700nm on Earth); and (2) the need to avoid UV-B radiation - prior to the production of an atmospheric UV screen of ozone - which would damage the organism's DNA. Significant photosynthesis with the generation of molecular oxygen could take place with an incident photon flux at the organism of at least ten times that on today's Earth. If the parent star is hot enough for there to be appreciable levels of UV radiation, photosynthetic organisms can seek lower UV light levels in the ELP ocean with the benefit of the greater attenuation of UV-B radiation than of the 400-700nm radiation. In the case of cool stars where the flux of photosynthetically active photons may be too low, a major change in the photosynthetic apparatus would be required from the two-photon photosystem of terrestrial photosynthesis, which energises the electron transfer needed in photosynthesis, to a three- or four-photon photosystem which can make use of lower energy photons. The implications for the viability and spectroscopic detectability of photosynthetic organisms on ELP's will be discussed.

  16. 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

  17. A Model for Estimating the Numbers of Stars for Which Terrestrial Planets Can Be Detected

    NASA Technical Reports Server (NTRS)

    Koch, David; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Borucki and Summers (1984) have suggested that extrasolar terrestrial planets can be detected by looking for transits. A discussion is presented of a model used to estimate the number of stars for which planets can be detected as a function of spectral type and luminosity, stellar brightness, planet size and realistic noise sources that must be considered. A choice for an optimum location of the field to search is described given the realistic constraints of a space mission and the desire to maximize the number of available stars.

  18. Educational And Public Outreach Software On Planet Detection For The Macintosh (TM)

    NASA Technical Reports Server (NTRS)

    Koch, David; Brady, Victoria; Cannara, Rachel; Witteborn, Fred C. (Technical Monitor)

    1996-01-01

    The possibility of extra-solar planets has been a very popular topic with the general public for years. Considerable media coverage of recent detections has only heightened the interest in the topic. School children are particularly interested in learning about space. Astronomers have the knowledge and responsibility to present this information in both an understandable and interesting format. Since most classrooms and homes are now equipped with computers this media can be utilized to provide more than a traditional "flat" presentation. An interactive "stack" has been developed using Hyperstudio (TM). The major topics include: "1996 - The Break Through Year In Planet Detection"; "What Determines If A Planet Is Habitable?"; "How Can We Find Other Planets (Search Methods)"; "All About the Kepler Mission: How To Find Earth-Sized Planets"; and "A Mission Simulator". Using the simulator, the student records simulated observations and then analyzes and interprets the data within the program stacks to determine the orbit and planet size, the planet's temperature and surface gravity, and finally determines if the planet is habitable. Additional related sections are also included. Many of the figures are animated to assist in comprehension of the material. A set of a dozen lesson plans for the middle school has also been drafted.

  19. Deep Space Detectives: Searching for Planets Suitable for Life

    ERIC Educational Resources Information Center

    Pallant, Amy; Damelin, Daniel; Pryputniewicz, Sarah

    2013-01-01

    This article describes the High-Adventure Science curriculum unit "Is There Life in Space?" This free online investigation, developed by The Concord Consortium, helps students see how scientists use modern tools to locate planets around distant stars and explore the probability of finding extraterrestrial life. This innovative curriculum…

  20. DETECTING THE WIND-DRIVEN SHAPES OF EXTRASOLAR GIANT PLANETS FROM TRANSIT PHOTOMETRY

    SciTech Connect

    Barnes, Jason W.; Cooper, Curtis S.; Showman, Adam P.; Hubbard, William B.

    2009-11-20

    Several processes can cause the shape of an extrasolar giant planet's shadow, as viewed in transit, to depart from circular. In addition to rotational effects, cloud formation, non-homogenous haze production and movement, and dynamical effects (winds) could also be important. When such a planet transits its host star as seen from the Earth, the asphericity will introduce a deviation in the transit light curve relative to the transit of a perfectly spherical (or perfectly oblate) planet. We develop a theoretical framework to interpret planetary shapes. We then generate predictions for transiting planet shapes based on a published theoretical dynamical model of HD189733b. Using these shape models we show that planet shapes are unlikely to introduce detectable light-curve deviations (those >1 x 10{sup -5} of the host star), but that the shapes may lead to astrophysical sources of systematic error when measuring planetary oblateness, transit time, and impact parameter.

  1. A Planet Hunters Search of the Kepler TCE Inventory

    NASA Astrophysics Data System (ADS)

    Schwamb, Meg; Lintott, Chris; Fischer, Debra; Smith, Arfon; Boyajian, Tabetha; Brewer, John; Giguere, Matt; Lynn, Stuart; Schawinski, Kevin; Simpson, Rob; Wang, Ji

    2013-07-01

    NASA's Kepler spacecraft has spent the past 4 years monitoring ~160,000 stars for the signatures of transiting exoplanets. Planet Hunters (http://www.planethunters.org), part of the Zooniverse (http://www.zooniverse.org) collection of citizen science projects, uses the power of human pattern recognition via the World Wide Web to identify transits in the Kepler public data. We have demonstrated the success of a citizen science approach with the project's discoveries including PH1 b, a transiting circumbinary planet in a four star system., and over 20 previously unknown planet candidates. The Kepler team has released the list of 18,406 potential transit signals or threshold-crossing events (TCEs) identified in Quarters 1-12 (~1000 days) by their automated Transit Planet Search (TPS) algorithm. The majority of these detections found by TPS are triggered by transient events and are not valid planet candidates. To identify planetary candidates from the detected TCEs, a human review of the validation reports, generated by the Kepler pipeline for each TCE, is performed by several Kepler team members. We have undertaken an independent crowd-sourced effort to perform a systematic search of the Kepler Q1-12 TCE list. With the Internet we can obtain multiple assessments of each TCE's data validation report. Planet Hunters volunteers evaluate whether a transit is visible in the Kepler light curve folded on the expected period identified by TPS. We present the first results of this analysis.

  2. Differential Astrometry to detect giant planets around A-stars

    NASA Astrophysics Data System (ADS)

    Monnier, John D.; Johnson, Keith; Swihart, Samuel; Ireland, Michael; Zhao, Ming; Ten Brummelaar, Theo

    2015-01-01

    The exoplanet field has remained vibrant and exciting due to the continuous development of new observing techniques and the refinement of older ones, both from the ground and from space. Here we propose to push the exoplanet frontier through the development of a new interferometric experiment that takes advantage of the Michigan Infrared Combiner (MIRC) on the CHARA Array, a visible and near-infrared interferometer boasting the longest baselines and finest angular resolution in the world. The ARMADA (ARrangement for Micro-Arcsecond Differential Astrometry) Project will search for astrometric wobble in a sample of hot stars (spectral type A,B) to search for giants planets in P<3 year orbits. Recent radial velocity (RV) work studying evolved sub-giants --``retired A stars" -- suggest up to a five-fold increase in the presence of massive gas giant planets in about 1 AU orbits compared to solar-type stars. Confirmation of this disputed result on A stars themselves would have profound effect on theories of planet formation but is difficult or impossible due to the broad, weak lines of hot stars. Using a novel etalon module already designed and fabricated to maintain precision wavelength calibration (Dl/l ~1x10-5), we aim to measure separations with <10 micro-arcsecond-level precision for binaries up to 0.25' separation.

  3. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2012-03-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  4. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2007-10-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  5. On the feasibility of detecting extrasolar planets by reflected starlight using the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.; Burrows, Christopher J.

    1990-01-01

    The best metrology data extant are presently used to estimate the center and wing point-spread function of the HST, in order to ascertain the implications of an observational criterion according to which a faint source's discovery can occur only when the signal recorded near its image's location is sufficiently larger than would be expected in its absence. After defining the maximum star-planet flux ratio, a figure of merit Q, defined as the contrast ratio between a 'best case' planet and the scattered starlight background, is introduced and shown in the HST's case to be unfavorable for extrasolar planet detection.

  6. Angular momentum exchange by gravitational torques and infall in the circumbinary disk of the protostellar system L1551 NE

    SciTech Connect

    Takakuwa, Shigehisa; Ho, Paul T. P.; Saito, Masao; Saigo, Kazuya; Matsumoto, Tomoaki; Lim, Jeremy; Hanawa, Tomoyuki

    2014-11-20

    We report an ALMA observation of the Class I binary protostellar system L1551 NE in the 0.9 mm continuum, C{sup 18}O (3-2), and {sup 13}CO (3-2) lines at a ∼1.6 times higher resolution and a ∼6 times higher sensitivity than those of our previous SubMillimeter Array (SMA) observations, which revealed a r ∼ 300 AU scale circumbinary disk in Keplerian rotation. The 0.9 mm continuum shows two opposing U-shaped brightenings in the circumbinary disk and exhibits a depression between the circumbinary disk and the circumstellar disk of the primary protostar. The molecular lines trace non-axisymmetric deviations from Keplerian rotation in the circumbinary disk at higher velocities relative to the systemic velocity, where our previous SMA observations could not detect the lines. In addition, we detect inward motion along the minor axis of the circumbinary disk. To explain the newly observed features, we performed a numerical simulation of gas orbits in a Roche potential tailored to the inferred properties of L1551 NE. The observed U-shaped dust features coincide with locations where gravitational torques from the central binary system are predicted to impart angular momentum to the circumbinary disk, producing shocks and hence density enhancements seen as a pair of spiral arms. The observed inward gas motion coincides with locations where angular momentum is predicted to be lowered by the gravitational torques. The good agreement between our observation and model indicates that gravitational torques from the binary stars constitute the primary driver for exchanging angular momentum so as to permit infall through the circumbinary disk of L1551 NE.

  7. Angular Momentum Exchange by Gravitational Torques and Infall in the Circumbinary Disk of the Protostellar System L1551 NE

    NASA Astrophysics Data System (ADS)

    Takakuwa, Shigehisa; Saito, Masao; Saigo, Kazuya; Matsumoto, Tomoaki; Lim, Jeremy; Hanawa, Tomoyuki; Ho, Paul T. P.

    2014-11-01

    We report an ALMA observation of the Class I binary protostellar system L1551 NE in the 0.9 mm continuum, C18O (3-2), and 13CO (3-2) lines at a ~1.6 times higher resolution and a ~6 times higher sensitivity than those of our previous SubMillimeter Array (SMA) observations, which revealed a r ~ 300 AU scale circumbinary disk in Keplerian rotation. The 0.9 mm continuum shows two opposing U-shaped brightenings in the circumbinary disk and exhibits a depression between the circumbinary disk and the circumstellar disk of the primary protostar. The molecular lines trace non-axisymmetric deviations from Keplerian rotation in the circumbinary disk at higher velocities relative to the systemic velocity, where our previous SMA observations could not detect the lines. In addition, we detect inward motion along the minor axis of the circumbinary disk. To explain the newly observed features, we performed a numerical simulation of gas orbits in a Roche potential tailored to the inferred properties of L1551 NE. The observed U-shaped dust features coincide with locations where gravitational torques from the central binary system are predicted to impart angular momentum to the circumbinary disk, producing shocks and hence density enhancements seen as a pair of spiral arms. The observed inward gas motion coincides with locations where angular momentum is predicted to be lowered by the gravitational torques. The good agreement between our observation and model indicates that gravitational torques from the binary stars constitute the primary driver for exchanging angular momentum so as to permit infall through the circumbinary disk of L1551 NE.

  8. PlanetPack software tool for exoplanets detection: coming new features

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2014-07-01

    We briefly overview the new features of PlanetPack2, the forthcoming update of PlanetPack, which is a software tool for exoplanets detection and characterization from Doppler radial velocity data. Among other things, this major update brings parallelized computing, new advanced models of the Doppler noise, handling of the so-called Keplerian periodogram, and routines for transits fitting and transit timing variation analysis.

  9. Circumbinary ring, circumstellar disks, and accretion in the binary system UY Aurigae

    SciTech Connect

    Tang, Ya-Wen; Ho, Paul T. P.; Dutrey, Anne; Guilloteau, Stéphane; Di Folco, Emmanuel; Piétu, Vincent; Gueth, Fréderic; Beck, Tracy; Boehler, Yann; Bary, Jeff; Simon, Michal

    2014-09-20

    Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary (CB) disks may be in the midst of planet formation. However, there are very few CB disks detected. We revisit one of the known CB disks, the UY Aurigae system, and probe {sup 13}CO 2-1, C{sup 18}O 2-1, SO 5(6)-4(5) and {sup 12}CO 3-2 line emission and the thermal dust continuum. Our new results confirm the existence of the CB disk. In addition, the circumstellar (CS) disks are clearly resolved in dust continuum at 1.4 mm. The spectral indices between the wavelengths of 0.85 mm and 6 cm are found to be surprisingly low, being 1.6 for both CS disks. The deprojected separation of the binary is 1.''26 based on our 1.4 mm continuum data. This is 0.''07 (10 AU) larger than in earlier studies. Combining the fact of the variation of UY Aur B in R band, we propose that the CS disk of an undetected companion UY Aur Bb obscures UY Aur Ba. A very complex kinematical pattern inside the CB disk is observed due to a mixing of Keplerian rotation of the CB disk, the infall and outflow gas. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.

  10. Properties and Detection Limits of Planetary Caustic Perturbation Induced by a Wide-separation Planet

    NASA Astrophysics Data System (ADS)

    Ryu, Yoon-Hyun; Chung, Sun-Ju; Lee, Ki-Won; Kim, Han-Seek; Han, Du-Hwan

    2016-03-01

    Microlensing experiments are entering a next generation of survey types to monitor a wide field of view continuously with a frequent sampling. The theoretically predicted sensitivity of a planet detection on the lensing parameters can be used for the establishment of observational strategies for maximal planet detections. Hence, we investigate the detection condition of planetary signals caused by the planetary caustic. We calculate the deviation area induced by the planetary caustic for various lensing parameters and find that the deviation area generally increases according to the increase of the source radius. However, after the normalized source radius approaches a certain value the deviation area rapidly decreases and disappears at the same normalized source radius, regardless of the mass ratio and the separation between the planet and its host star. We find a simple relation between the normalized source radius and the deviation threshold for the largest and smallest deviation areas. From this relation we also find an analytic condition for the detection limit of the planetary signal as the function of the source radius and the deviation threshold. In addition, we compare the deviation areas and the light curves between the planetary caustic perturbation and a free-floating planet. We find that the planetary caustic perturbation can be approximated by the single-lensing light curve of the planet itself perturbed by the planetary caustic. Finally, we can expect to find a low-mass planet with the Earth’s mass or even that of the Earth's moon from the detection condition and conclude that our findings may help for maximal planet detections considering the source type and the photometric accuracy.

  11. DETECTABILITY AND ERROR ESTIMATION IN ORBITAL FITS OF RESONANT EXTRASOLAR PLANETS

    SciTech Connect

    Giuppone, C. A.; Beauge, C.; Tadeu dos Santos, M.; Ferraz-Mello, S.; Michtchenko, T. A.

    2009-07-10

    We estimate the conditions for detectability of two planets in a 2/1 mean-motion resonance from radial velocity data, as a function of their masses, number of observations and the signal-to-noise ratio. Even for a data set of the order of 100 observations and standard deviations of the order of a few meters per second, we find that Jovian-size resonant planets are difficult to detect if the masses of the planets differ by a factor larger than {approx}4. This is consistent with the present population of real exosystems in the 2/1 commensurability, most of which have resonant pairs with similar minimum masses, and could indicate that many other resonant systems exist, but are currently beyond the detectability limit. Furthermore, we analyze the error distribution in masses and orbital elements of orbital fits from synthetic data sets for resonant planets in the 2/1 commensurability. For various mass ratios and number of data points we find that the eccentricity of the outer planet is systematically overestimated, although the inner planet's eccentricity suffers a much smaller effect. If the initial conditions correspond to small-amplitude oscillations around stable apsidal corotation resonances, the amplitudes estimated from the orbital fits are biased toward larger amplitudes, in accordance to results found in real resonant extrasolar systems.

  12. The OGLE-III planet detection efficiency from six years of microlensing observations (2003-2008)

    NASA Astrophysics Data System (ADS)

    Tsapras, Y.; Hundertmark, M.; Wyrzykowski, Ł.; Horne, K.; Udalski, A.; Snodgrass, C.; Street, R.; Bramich, D. M.; Dominik, M.; Bozza, V.; Figuera Jaimes, R.; Kains, N.; Skowron, J.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Kozłowski, S.; Pietrukowicz, P.; Poleski, R.

    2016-04-01

    We use six years (2003-2008) of Optical Gravitational Lensing Experiment-III microlensing observations to derive the survey detection efficiency for a range of planetary masses and projected distances from the host star. We perform an independent analysis of the microlensing light curves to extract the event parameters and compute the planet detection probability given the data. 2433 light curves satisfy our quality selection criteria and are retained for further processing. The aggregate of the detection probabilities over the range explored yields the expected number of microlensing planet detections. We employ a Galactic model to convert this distribution from dimensionless to physical units, α/au and M⊕. The survey sensitivity to small planets is highest in the range 1-4 au, shifting to slightly larger separations for more massive ones.

  13. Activity induced detection limits for Earth-sized planets from radial velocity studies

    NASA Astrophysics Data System (ADS)

    Korhonen, Heidi; Gråe Jørgensen, Uffe; Andersen, Jan Marie

    2015-08-01

    The detection of exoplanets using any method is prone to confusion due to the intrinsic variability of the host star. We have recently investigated the effect of cool starspots on the detectability of exoplanets around solar-like stars and M dwarfs using the radial velocity method. Our methods use full radiative transfer, known stellar atomic and molecular lines, different surface spot configurations, and an added planetary signal. In this talk we present our methods, and apply them to studying the detectability of small planets, and especially the case of alpha Centauri B planet.

  14. Detection of Close-In Extrasolar Giant Planets Using theFourier-Kelvin Stellar Interferometer

    NASA Astrophysics Data System (ADS)

    Danchi, William C.; Deming, Drake; Kuchner, Marc J.; Seager, Sara

    2003-11-01

    We evaluate the direct detection of extrasolar giant planets with a two-aperture nulling infrared interferometer, working at angles θ<λ/2B and using a new ``ratio-of-two-wavelengths'' technique. Simple arguments suggest that interferometric detection and characterization should be quite possible for planets much closer than the conventional inner working angle, or angular resolution limit. We show that the peak signal from a nulling infrared interferometer of baseline <~40 m will often occur ``inside the null'' and that the signal variations from path difference fluctuations will cancel to first order in the ratio of two wavelengths. Using a new interferometer simulation code, we evaluate the detectability of all the known extrasolar planets as observed using this two-color method with the proposed Fourier-Kelvin Stellar Interferometer (FKSI). In its minimum configuration FKSI uses two 0.5 m apertures on a 12.5 m baseline and a +/-20° field of regard. We predict that ~7 known extrasolar planets are directly detectable using FKSI, with low-resolution spectroscopy (R~20) being possible in the most favorable cases. Spaceborne direct detection of extrasolar giant planets is possible with ~12 m baselines and does not require the much longer baselines provided by formation flying.

  15. Toward Detection of Terrestrial Planets in the Habitable Zone of Our Closest Neighbor: Proxima Centauri

    NASA Astrophysics Data System (ADS)

    Endl, Michael; Kuerster, M.

    2009-01-01

    In recent years the precision of radial velocity (RV) measurements for the indirect detection of planetary companions to nearby stars has improved to a level that allowed the first discoveries of extrasolar planets in the Neptune and Super-Earth mass range. Detections of extremely low mass planets, possibly even down to 1 Earth mass or below, in short-period orbits can lie in the mid-term future of RV planet searches. Discoveries of such Earth-like planets via ground-based RV programs will help to determine the parameter eta_Earth, the frequency of potentially habitable planets around other stars. We monitored Proxima Centauri (M5V) as part of our M dwarf program in search of low-mass planetary companions. In the absence of a significant detection we want to use these data to demonstrate the general capability of the RV method to find terrestrial planets. For late M dwarfs the classic liquid surface water habitable zone (HZ) is located very close to the star, precisely where the RV method is most sensitive. We determine upper limits to the masses of companions in circular orbits via numerical simulations. As a result of our companion limit calculations we find that we successfully recover all test signals with RV amplitudes corresponding to planets with m sin i > 2-3 M_Earth residing inside the HZ of Proxima Cen with a statistical significance of >99%. Over the same period range we can recover 50% of the test planets with masses of m sin i > 1.5-2.5 M_Earth. We also discuss the effects of stellar activity on our RV measurements.

  16. SIM Lite Detection of Habitable Planets in P-Type Binary-Planetary Systems

    NASA Technical Reports Server (NTRS)

    Pan, Xiaopei; Shao, Michael; Shaklan, Stuart; Goullioud, Renaud

    2010-01-01

    Close binary stars like spectroscopic binaries create a completely different environment than single stars for the evolution of a protoplanetary disk. Dynamical interactions between one star and protoplanets in such systems provide more challenges for theorists to model giant planet migration and formation of multiple planets. For habitable planets the majority of host stars are in binary star systems. So far only a small amount of Jupiter-size planets have been discovered in binary stars, whose minimum separations are 20 AU and the median value is about 1000 AU (because of difficulties in radial velocity measurements). The SIM Lite mission, a space-based astrometric observatory, has a unique capability to detect habitable planets in binary star systems. This work analyzed responses of the optical system to the field stop for companion stars and demonstrated that SIM Lite can observe exoplanets in visual binaries with small angular separations. In particular we investigated the issues for the search for terrestrial planets in P-type binary-planetary systems, where the planets move around both stars in a relatively distant orbit.

  17. SIM-Lite detection of habitable planets in P-type binary-planetary systems

    NASA Astrophysics Data System (ADS)

    Pan, Xiaopei; Shao, Michael; Shaklan, Stuart; Goullioud, Renaud

    2010-07-01

    Close binary stars like spectroscopic binaries create a completely different environment than single stars for the evolution of a protoplanetary disk. Dynamical interactions between one star and protoplanets in such systems provide more challenges for theorists to model giant planet migration and formation of multiple planets. For habitable planets the majority of host stars are in binary star systems. So far only a small amount of Jupiter-size planets have been discovered in binary stars, whose minimum separations are 20 AU and the median value is about 1000 AU (because of difficulties in radial velocity measurements). The SIM Lite mission, a space-based astrometric observatory, has a unique capability to detect habitable planets in binary star systems. This work analyzed responses of the optical system to the field stop for companion stars and demonstrated that SIM Lite can observe exoplanets in visual binaries with small angular separations. In particular we investigated the issues for the search for terrestrial planets in P-type binary-planetary systems, where the planets move around both stars in a relatively distant orbit.

  18. Formation and detection of Earth mass planets around low mass stars

    NASA Astrophysics Data System (ADS)

    Montgomery, Ryan; Laughlin, Gregory

    2009-07-01

    We investigate an in situ formation scenario for Earth-mass terrestrial planets in short-period, potentially habitable orbits around low-mass stars (M∗ < 0.3M⊙). We then investigate the feasibility of detecting these Earth-sized planets. We find that such objects can feasibly be detected by a ground-based transit survey if their formation frequency is high and if correlated noise can be controlled to sub-milli-magnitude levels. Our simulations of terrestrial planet formation follow the growth of planetary embryos in an annular region spanning 0.036 AU ⩽ a ⩽ 0.4 AU around a fiducial M7 (0.12M⊙) primary. Initial distributions of planetary embryos are calculated using the semi-analytic evolutionary model outlined by Chambers [Chambers, J., 2006. Icarus 180, 496-513]. This model specifies how planetary embryos grow to the stage where the largest embryo masses lie in the 1024 g ⩽Membryo ⩽ 5 ×1026 g range (corresponding to the close of the so-called oligarchic growth phase). We then model the final phases of terrestrial planet assembly by allowing the embryos to interact with one another via a full N-body integration using the Mercury code. The final planetary system configurations produced in the simulations generally consist of 3-5 planets with masses of order 0.1- 1.0M⊕ in or near the habitable zone of the star. We explore a range of disk masses (0.2M⊕ to 3.3M⊕) to illuminate the role disk mass plays in our results. With a high occurrence fraction or fortunate alignments, transits by the planet formed in our simulations could be marginally detected with modest telescopes of aperture 1 m or smaller around the nearest M-dwarf stars. To obtain a concrete estimate of the detectability of the planets arising in our simulations, we present a detailed Monte-Carlo transit detection simulation incorporating sky observability, local weather, a target list of around 200 nearby M-dwarfs, and a comprehensive photometric noise model. We adopt a baseline 1

  19. A Single Circumbinary Disk in the HD 98800 Quadruple System

    NASA Astrophysics Data System (ADS)

    Koerner, D. W.; Jensen, E. L. N.; Cruz, K.; Guild, T. B.; Gultekin, K.

    1999-12-01

    We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'', each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optical secondary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 146 K. With the assumption that the dust is in radiative equilibrium with the central stars, these characteristics require its location to be in a configuration that is circumbinary to the spectroscopic pair. A simple black-body fit underpredicts emission in the region of the broad silicate feature, however, and the feature itself requires a dust component with temperatures higher than 146 K by at least a factor of two. Further, the spectral slope at sub-millimeter wavelengths is flatter than expected for a collision-induced size-distribution of grains, suggesting a range of temperatures present at longer wavelengths. These facts suggest that the circumbinary dust is not confined to a narrow ring but is wide enough to exhibit a range of temperatures.

  20. Darwin--a mission to detect and search for life on extrasolar planets.

    PubMed

    Cockell, C S; Léger, A; Fridlund, M; Herbst, T M; Kaltenegger, L; Absil, O; Beichman, C; Benz, W; Blanc, M; Brack, A; Chelli, A; Colangeli, L; Cottin, H; Coudé du Foresto, F; Danchi, W C; Defrère, D; den Herder, J-W; Eiroa, C; Greaves, J; Henning, T; Johnston, K J; Jones, H; Labadie, L; Lammer, H; Launhardt, R; Lawson, P; Lay, O P; LeDuigou, J-M; Liseau, R; Malbet, F; Martin, S R; Mawet, D; Mourard, D; Moutou, C; Mugnier, L M; Ollivier, M; Paresce, F; Quirrenbach, A; Rabbia, Y D; Raven, J A; Rottgering, H J A; Rouan, D; Santos, N C; Selsis, F; Serabyn, E; Shibai, H; Tamura, M; Thiébaut, E; Westall, F; White, G J

    2009-01-01

    The discovery of extrasolar planets is one of the greatest achievements of modern astronomy. The detection of planets that vary widely in mass demonstrates that extrasolar planets of low mass exist. In this paper, we describe a mission, called Darwin, whose primary goal is the search for, and characterization of, terrestrial extrasolar planets and the search for life. Accomplishing the mission objectives will require collaborative science across disciplines, including astrophysics, planetary sciences, chemistry, and microbiology. Darwin is designed to detect rocky planets similar to Earth and perform spectroscopic analysis at mid-infrared wavelengths (6-20 mum), where an advantageous contrast ratio between star and planet occurs. The baseline mission is projected to last 5 years and consists of approximately 200 individual target stars. Among these, 25-50 planetary systems can be studied spectroscopically, which will include the search for gases such as CO(2), H(2)O, CH(4), and O(3). Many of the key technologies required for the construction of Darwin have already been demonstrated, and the remainder are estimated to be mature in the near future. Darwin is a mission that will ignite intense interest in both the research community and the wider public. PMID:19203238

  1. VizieR Online Data Catalog: OGLE-III planet detection efficiency (Tsapras+, 2016)

    NASA Astrophysics Data System (ADS)

    Tsapras, Y.; Hundertmark, M.; Wyrzykowski, L.; Horne, K.; Udalski, A.; Snodgrass, C.; Street, R.; Bramich, D. M.; Dominik, M.; Bozza, V.; Figuera Jaimes, R.; Kains, N.; Skowron, J.; Szymanski, M. K.; Pietrzynski, G.; Soszynski, I.; Ulaczyk, K.; Kozlowski, P.; Pietrukowicz, S.; Poleski, R.

    2016-02-01

    The FITS file represents the surface plotted in Figure 10, which is the main result of the paper. Each pixel value in the FITS file represents the expected number of planet detections at a specific planetary mass and orbital radius, assuming that each star surveyed has a single such planet (see figure caption for more details). The FITS file contains a world coordinate system in the header which gives coordinates to each pixel. The x coordinate is the log10(orbital radius in AU), and the y coordinate is the log 10(planet mass in Earth masses). The data product is essential for any further analysis of planet abundances using the original OGLE light curve data. (2 data files).

  2. The detection and characterization of a nontransiting planet by transit timing variations.

    PubMed

    Nesvorný, David; Kipping, David M; Buchhave, Lars A; Bakos, Gáspár Á; Hartman, Joel; Schmitt, Allan R

    2012-06-01

    The Kepler mission is monitoring the brightness of ~150,000 stars, searching for evidence of planetary transits. As part of the Hunt for Exomoons with Kepler (HEK) project, we report a planetary system with two confirmed planets and one candidate planet discovered with the publicly available data for KOI-872. Planet b transits the host star with a period P(b) = 33.6 days and exhibits large transit timing variations indicative of a perturber. Dynamical modeling uniquely detects an outer nontransiting planet c near the 5:3 resonance (P(c) = 57.0 days) with a mass 0.37 times that of Jupiter. Transits of a third planetary candidate are also found: a 1.7-Earth radius super-Earth with a 6.8-day period. Our analysis indicates a system with nearly coplanar and circular orbits, reminiscent of the orderly arrangement within the solar system. PMID:22582018

  3. The Photometric Method for the Detection of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Giampapa, M. S.; Craine, E. R.; Hott, D. A.

    1995-12-01

    We offer further perspectives on the application of the photometric technique to the search for extrasolar planets. The principal obstacles to this approach include (1) the ambiguous interpretation of the photometric signature of a possible transit event arising from the potential for confusion with stellar activity, and (2) the observational intensity of the search technique. We emphasize that the former issue can be addressed through multiband observations combined with considerations of the characteristic time scales of forms of stellar activity compared to that of a transit event. In the case of the latter concern, the advent of modern, automated telescope technologies offers the realistic prospect of meeting the demanding observational requirements of this approach. We find that joint visual and near infrared observations are necessary to immediately distinguish between, for example, a planetary transit and a cool spot on the stellar surface. However, these observations by themselves do not appear sufficient to distinguish between a brown dwarf and a Jovian-size planetary companion of a dwarf M star. In such cases, other complementary observations will be necessary. We develop a computer simulation to estimate the average number of transits per year that would be presented for a stellar sample characterized by realistic properties in terms of spectral type distribution, effective temperatures, masses, and radii. A simple thermal model is adopted to estimate star-planet separations. The simulation suggests that the frequency of transit events will be dominated by M dwarf systems. This is due to the large number of these objects combined with the relative proximity to these cool stars within which planetary formation can occur according to current models.

  4. χ2 Discriminators for Transiting Planet Detection in Kepler Data

    NASA Astrophysics Data System (ADS)

    Seader, Shawn; Tenenbaum, P.; Jenkins, J.

    2012-10-01

    The Kepler Mission continuously observes a host of target stars in a 115 square-degree field of view to discover Earth-like planets transiting Sun-like stars through analysis of photometric data. The Kepler Science Operations Center at NASA Ames Research Center processes the data with the Science Processing Pipeline, which is composed of several modules including the Transiting Planet Search (TPS). To search for transit signatures, TPS employs a bank of wavelet-based matched filters that form a grid on a three dimensional parameter space of transit duration, period, and epoch. Owing to non-stationary and non-Gaussian noise, uncorrected systematics, and poorly mitigated noise events of either astrophysical or non-astrophysical nature, large spurious Threshold Crossing Events (TCE’s) can be produced by the matched filtering performed in TPS. These false alarms waste resources as they propagate through the remainder of the Pipeline, and so a method to discriminate against them is crucial in maintaining the desired sensitivity to true events. Here we describe four separate χ2 tests which represent a novel application of the formalism developed by Allen for false alarm mitigation in searches for gravitational waves. The basic idea behind these vetoes is to break up the matched filter output into several contributions and compare each contribution with what is expected under the assumption that a true signal is present in the data. Vetoes can then be constructed which, under certain assumptions, have been shown to be χ2 distributed with expectation values that are independent of whether or not a true signal is present, thereby making them useful discriminators. The four different ways of breaking up the output and forming χ2 vetoes illustrated here, allow discrimination against different classes of false alarms. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science Mission Directorate.

  5. Detection and Characterization of Extrasolar Planets through Mean-motion Resonances. I. Simulations of Hypothetical Debris Disks

    NASA Astrophysics Data System (ADS)

    Tabeshian, Maryam; Wiegert, Paul A.

    2016-02-01

    The gravitational influence of a planet on a nearby disk provides a powerful tool for detecting and studying extrasolar planetary systems. Here we demonstrate that gaps can be opened in dynamically cold debris disks at the mean-motion resonances of an orbiting planet. The gaps are opened away from the orbit of the planet itself, revealing that not all disk gaps need contain a planetary body. These gaps are large and deep enough to be detectable in resolved disk images for a wide range of reasonable disk-planet parameters, though we are not aware of any such gaps detected to date. The gap shape and size are diagnostic of the planet location, eccentricity and mass, and allow one to infer the existence of unseen planets, as well as many important parameters of both seen and unseen planets in these systems. We present expressions to allow the planetary mass and semimajor axis to be calculated from observed gap width and location.

  6. Detecting Close-In Extrasolar Giant Planets with the Kepler Photometer via Scattered Light

    NASA Astrophysics Data System (ADS)

    Jenkins, J. M.; Doyle, L. R.; Kepler Discovery Mission Team

    2003-05-01

    NASA's Kepler Mission will be launched in 2007 primarily to search for transiting Earth-sized planets in the habitable zones of solar-like stars. In addition, it will be poised to detect the reflected light component from close-in extrasolar giant planets (CEGPs) similar to 51 Peg b. Here we use the DIARAD/SOHO time series along with models for the reflected light signatures of CEGPs to evaluate Kepler's ability to detect such planets. We examine the detectability as a function of stellar brightness, stellar rotation period, planetary orbital inclination angle, and planetary orbital period, and then estimate the total number of CEGPs that Kepler will detect over its four year mission. The analysis shows that intrinsic stellar variability of solar-like stars is a major obstacle to detecting the reflected light from CEGPs. Monte Carlo trials are used to estimate the detection threshold required to limit the total number of expected false alarms to no more than one for a survey of 100,000 stellar light curves. Kepler will likely detect 100-760 51 Peg b-like planets by reflected light with orbital periods up to 7 days. LRD was supported by the Carl Sagan Chair at the Center for the Study of Life in the Universe, a division of the SETI Institute. JMJ received support from the Kepler Mission Photometer and Science Office at NASA Ames Research Center.

  7. Detecting Planet Pairs in Mean Motion Resonances via the Astrometry Method

    NASA Astrophysics Data System (ADS)

    Wu, Dong-Hong; Liu, Hui-Gen; Yu, Zhou-Yi; Zhang, Hui; Zhou, Ji-Lin

    2016-07-01

    Gaia is leading us into a new era with a high astrometry precision of ˜10 μas. Under such precision, astrometry can play an important role in detecting and characterizing exoplanets. In particular, we can identify planet pairs in mean motion resonances (MMRs), which constrain the formation and evolution of planetary systems. In accordance with observations, we consider two-Jupiter or two-super-Earth systems in 1:2, 2:3, and 3:4 MMRs. Our simulations show that the false alarm probabilities (FAPs) of a third planet are extremely small, while the two real planets can be fitted well with a signal-to-noise ratio (S/N) \\gt 3. The probability of reconstructing a resonant system is related to the eccentricities and the resonance intensity. Generally, when the S/N ≥slant 10, if the eccentricities of both planets are larger than 0.01 and the resonance is quite strong, the probability of reconstructing the planet pair in MMRs is ≥slant 80 % . Jupiter pairs in MMRs are reconstructed more easily than super-Earth pairs with similar S/N when we consider dynamical stability. FAPs are also calculated when we detect planet pairs in or near MMRs. The FAPs for 1:2 MMRs are the largest, i.e., FAP \\gt 15 % when S/N ≤slant 10. Extrapolating from the Kepler planet pairs near MMRs and assuming a S/N ˜ 3, we discover and reconstruct a few tens of Jupiter pairs and hundreds of super-Earth pairs in 2:3 and 1:2 MMRs within 30 pc. We also compare the differences between even and uneven data cadence and find that planets are better measured with more uniform phase coverage.

  8. THE CIRCUMBINARY OUTFLOW: A PROTOSTELLAR OUTFLOW DRIVEN BY A CIRCUMBINARY DISK

    SciTech Connect

    Machida, Masahiro N.; Inutsuka, Shu-ichiro; Matsumoto, Tomoaki E-mail: inutsuka@nagoya-u.j

    2009-10-10

    Protostellar outflow is a star's first cry at the moment of birth. The outflows have an indispensable role in the formation of single stars because they carry off the excess angular momentum from the center of the shrinking gas cloud, and permit further collapse to form a star. On the other hand, a significant fraction of stars is supposedly born as binaries with circumbinary disks that are frequently observed. Here, we investigate the evolution of a magnetized rotating cloud using a three-dimensional resistive MHD nested-grid code, and show that the outflow is driven by the circumbinary disk and has an important role even in the binary formation. After the adiabatic core formation in the collapsing cloud core, the magnetic flux is significantly removed from the center of the cloud by the Ohmic dissipation. Since this removal makes the magnetic braking ineffective, the adiabatic core continuously acquires the angular momentum to induce fragmentation and subsequent binary formation. The magnetic field accumulates in the circumbinary disk where the removal and accretion of magnetic field are balanced, and finally drives the circumbinary outflow. This result explains the spectacular morphology of some specific young stellar objects such as L1551 IRS5. We can infer that most of the bipolar molecular outflows observed by low density tracers (i.e., CO) would correspond to circumbinary or circum-multiple outflows found in this Letter, since most of the young stellar objects are supposed to be binaries or multiples.

  9. The detectability of extrasolar terrestrial and giant planets during their luminous final accretion

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1994-01-01

    One of the outstanding scientific questions in astronomy is the frequency at which solar systems form. Answering this question is an observational challenge because extrasolar planets are intrinsically difficult to directly detect. The direct detectability of planets is examined during the short but unique epoch of giant impacts that is a hallmark of the standard theory of planetary formation. Sufficiently large impacts during this era are capable of creating a luminous, 1500-2500 K photosphere, which can persist for timescales exceeding 103 years in some cases. The detectability of such events and the number of young stars one would need to examine to expect to find a luminous terrestrial class planet after a giant impact are examined. With emerging IR interferometric technology, thermally-luminous earth-sized objects can be detected in nearby star forming regions in 1-2 nights observing time. Unfortunately, predictions indicate that approximately 250 young stars would have to be searched to expect to find one hot, terrestrial-sized planet. By comparison, the detection of Saturn and Uranus/Neptune-sized planets after a giant impact requires only 1-2 hours of observing time. A single Keck-class telescope should be able to determine whether such planets are common in the nearest star forming regions by examining about less than 100 young stars over a few tens of nights. The results obtained herein suggest a new strategy for the detection of solar systems with the potential for the observational confirmation of the standard theory of late-stage planetary accretion.

  10. The detectability of extrasolar terrestrial and giant planets during their luminous final accretion

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1994-01-01

    One of the outstanding scienfific questions in astronomy is the frequency at which solar systems form. Answering this question is an observational challenge because extrasolar planets are intrinsically difficult to directly detect. Here I examine the direct detectability of planets during the short but unique epoch of giant impacts that is a hallmark of the standard theory of planetary formation. Sufficiently large impacts during this era are capable of creating a luminous, 1500-2500 K photosphere, which can persist for time scales exceeding 10(exp 3) yr in some cases. I examine the detectability of such events and the number of young stars one would need to examine to expect to find a luminous terrestrial-class planet after a giant impact. With emerging IR interferometric technology, thermally luminous Earth-sized objects can be detected in nearby star forming regions in 1-2 nights of observing time. Unfortunately, predictions indicated that approximately 250 young stars would have to be searched to expect to find one hot, terrestrial-sized planet. By comparison, the detection of Saturn and Uranus-Neptune-sized planets after a giant impact requires only 1-2 h of observing time. A single Keck-class telescope should be able to determine whether such planets are common in the nearest star forming regions by examining less than or approximately equal to 100 young stars over a few tens of nights. The results obtained here suggest a new strategy for the detection of solar systems with the potential for the observational confirmation of the standard theory of late-stage planetary accretion.

  11. Modelling circumbinary protoplanetary disks. I. Fluid simulations of the Kepler-16 and 34 systems

    NASA Astrophysics Data System (ADS)

    Lines, S.; Leinhardt, Z. M.; Baruteau, C.; Paardekooper, S.-J.; Carter, P. J.

    2015-10-01

    Context. The Kepler mission's discovery of a number of circumbinary planets orbiting close (ap< 1.1 au) to the stellar binary raises questions as to how these planets could have formed given the intense gravitational perturbations the dual stars impart on the disk. The gas component of circumbinary protoplanetary disks is perturbed in a similar manner to the solid, planetesimal dominated counterpart, although the mechanism by which disk eccentricity originates differs. Aims: This is the first work of a series that aims to investigate the conditions for planet formation in circumbinary protoplanetary disks. Methods: We present a number of hydrodynamical simulations that explore the response of gas disks around two observed binary systems: Kepler-16 and Kepler-34. We probe the importance of disk viscosity, aspect-ratio, inner boundary condition, initial surface density gradient, and self-gravity on the dynamical evolution of the disk, as well as its quasi-steady-state profile. Results: We find there is a strong influence of binary type on the mean disk eccentricity, e̅d, leading to e̅d = 0.02 - 0.08 for Kepler-16 and e̅d = 0.10 - 0.15 in Kepler-34. The value of α-viscosity has little influence on the disk, but we find a strong increase in mean disk eccentricity with increasing aspect-ratio due to wave propagation effects. The choice of inner boundary condition only has a small effect on the surface density and eccentricity of the disk. Our primary finding is that including disk self-gravity has little impact on the evolution or final state of the disk for disks with masses less than 12.5 times that of the minimum-mass solar nebula. This finding contrasts with the results of self-gravity relevance in circumprimary disks, where its inclusion is found to be an important factor in describing the disk evolution.

  12. Eclipse timing variations to detect possible Trojan planets in binary systems

    NASA Astrophysics Data System (ADS)

    Schwarz, R.; Bazsó, Á.; Funk, B.; Zechner, R.

    2015-11-01

    This paper is devoted to study the circumstances favourable to detect Trojan planets in close binary star systems by the help of eclipse timing variations (ETVs). To determine the probability of the detection of such variations with ground-based telescopes and space telescopes (like former missions CoRoT and Kepler and future space missions like PLATO, TESS and CHEOPS), we investigated the dynamics of binary star systems with a planet in tadpole motion. We did numerical simulations by using the full three-body problem as a dynamical model. The stability and the ETVs are investigated by computing stability/ETV maps for different masses of the secondary star and the Trojan planet. In addition, we changed the eccentricity of the possible Trojan planet. By the help of the libration amplitude σ, we could show whether or not all stable objects are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are large enough to detect Earth-like Trojan planets in binary star systems. As an application, we prepared a list of possible candidates.

  13. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    SciTech Connect

    Evans, J W

    2006-08-18

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10{sup -6} and 10{sup -7} at angles of 4-24 {lambda}/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10{sup -8} contrast measurements with a prolate shaped pupil and flat mirror

  14. Habitability of Planets Orbiting Binaries Consisting of Solar Mass Twins

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Zuluaga, Jorge I.; Zhilkin, Andrey G.; Bisikalo, Dmitry V.

    2015-01-01

    An important problem in astrobiology is the study of the potential habitability of planets orbiting binary stars. Theoretical and observational studies of circumbinary planets indicate that it is not uncommon for circumbinary planets to be located in the habitable zones surrounding main sequence binaries. However, it is also clear that the time evolution of stellar activity of the individual stars in close binaries is of primary concern for the habitability of planets. For example, planets orbiting active stars may lose the entirety of their water budget due to atmospheric mass loss; despite being in the standard radiative habitable zone. Alternatively, stars in some binaries may undergo a reduction in stellar activity due to tidal effects that cause the rotation of the stars to slow faster than single stars. Thereby, magneto-coronal activity is reduced to less aggressive levels, allowing circumbinary planets to maintain surface water. We summarize these effects, which we call the Binary Habitability Mechanism (BHM). We performed orbital integrations of circumbinary, Earth-like, planets and find that resonances play a particularly important role in the stability of habitable zone planets orbiting solar twin binaries in the 20-60 day period range, allowing for the possibility of several habitable planets orbiting some binaries. We present numerical simulations of the effects of colliding winds in binaries containing solar mass twins. We used stellar wind parameters based on solar like conditions for our 3D hydrodynamic simulations. We find devastating effects for close in planets, yet relatively mild stellar wind conditions exist within the circumbinary habitable zone.

  15. Optical techniques for the detection of extrasolar planets - A critical review

    NASA Technical Reports Server (NTRS)

    Matloff, G. L.; Fennelly, A. J.

    1976-01-01

    Proposed optical techniques of extrasolar planet detection are discussed and compared. These include terrestrial, orbital, and moon-based systems. Terrestrial systems include ground-level searches for random eclipses of primaries and 'light' echoes of stellar flares from companion planets as well as balloon-mounted telescopes operating in the stratosphere used in conjunction with orbital occulters. Space telescopes considered are multimirror systems simulating huge mirror diameters and single-mirror telescopes, such as the 3-meter Large Space Telescope, used in conjunction with occulters. Although very modest systems are capable of detecting extrasolar planets, the amount of information we can gather regarding these worlds is a function of system complexity and program duration.

  16. Use of the moon and the large space telescope as an extrasolar planet detection system

    NASA Technical Reports Server (NTRS)

    Matloff, G. L.; Fennelly, A. J.

    1974-01-01

    Roman (1959), Spitzer (1962), and Huang (1973) have discussed photometric detection of extrasolar planets using a 3-m space telescope such as the Large Space Telescope (LST). A space telescope could be an extrasolar planet detection system if used in conjunction with an occulter placed 10,000 km in front of the telescope. The occulter would reduce the amount of light received from the star under observation. For a semi-infinite plane occulter 10,000 km in front of the telescope, Spitzer and Huang's results indicate that a Jupiter-like planet would be observed with a signal/noise of 1.00, for observations at 0.4 micron using a 3-m telescope like the LST.

  17. On the Detection of Non-transiting Hot Jupiters in Multiple-planet Systems

    NASA Astrophysics Data System (ADS)

    Millholland, Sarah; Wang, Songhu; Laughlin, Gregory

    2016-05-01

    We outline a photometric method for detecting the presence of a non-transiting short-period giant planet in a planetary system harboring one or more longer-period transiting planets. Within a prospective system of the type that we consider, a hot Jupiter on an interior orbit inclined to the line of sight signals its presence through approximately sinusoidal full-phase photometric variations in the stellar light curve, correlated with astrometrically induced transit timing variations for exterior transiting planets. Systems containing a hot Jupiter along with a low-mass outer planet or planets on inclined orbits are a predicted hallmark of in situ accretion for hot Jupiters, and their presence can thus be used to test planetary formation theories. We outline the prospects for detecting non-transiting hot Jupiters using photometric data from typical Kepler objects of interest (KOIs). As a demonstration of the technique, we perform a brief assessment of Kepler candidates and identify a potential non-transiting hot Jupiter in the KOI-1822 system. Candidate non-transiting hot Jupiters can be readily confirmed with a small number of Doppler velocity observations, even for stars with V ≳ 14.

  18. Study of meteoroid detection systems applicable to the outer planets missions

    NASA Technical Reports Server (NTRS)

    Brooks, A. D.; Parker, C. D.; Monteith, L. K.

    1973-01-01

    Modifications to the Pioneer 10/11 meteoroid detection experiment to allow it to be used for outer planet missions were investigated. Both pressurized cells and metal-oxide silicon (MOS) penetration detectors are considered. Both the sensors systems and the electronics are treated. Investigation of the calibration and characterization of the MOS penetration detector is reported.

  19. Planets in Evolved Binary Systems

    NASA Astrophysics Data System (ADS)

    Perets, Hagai B.

    2011-03-01

    Exo-planets are typically thought to form in protoplanetary disks left over from protostellar disk of their newly formed host star. However, additional planetary formation and evolution routes may exist in old evolved binary systems. Here we discuss the implications of binary stellar evolution on planetary systems in such environments. In these binary systems stellar evolution could lead to the formation of symbiotic stars, where mass is lost from one star and could be transferred to its binary companion, and may form an accretion disk around it. This raises the possibility that such a disk could provide the necessary environment for the formation of a new, second generation of planets in both circumstellar or circumbinary configurations. Pre-existing first generation planets surviving the post-MS evolution of such systems would be dynamically effected by the mass loss in the systems and may also interact with the newly formed disk. Such planets and/or planetesimals may also serve as seeds for the formation of the second generation planets, and/or interact with them, possibly forming atypical planetary systems. Second generation planetary systems should be typically found in white dwarf binary systems, and may show various observational signatures. Most notably, second generation planets could form in environment which are inaccessible, or less favorable, for first generation planets. The orbital phase space available for the second generation planets could be forbidden (in terms of the system stability) to first generation planets in the pre-evolved progenitor binaries. In addition planets could form in metal poor environments such as globular clusters and/or in double compact object binaries. Observations of exo-planets in such forbidden or unfavorable regions could possibly serve to uniquely identify their second generation character. Finally, we point out a few observed candidate second generation planetary systems, including Gl 86, HD 27442 and all of the

  20. On the RZ Draconis substellar circumbinary companions. Stability study of the proposed substellar circumbinary system

    NASA Astrophysics Data System (ADS)

    Hinse, Tobias C.; Horner, Jonathan; Lee, Jae Woo; Wittenmyer, Robert A.; Lee, Chung-Uk; Park, Jang-Ho; Marshall, Jonathan P.

    2014-05-01

    Context. Recently, using the light-travel time effect, planets and substellar companions have been proposed to orbit around binary star systems (also known as circumbinary companions) as a result of variations in timing of the observed eclipses. For the majority of these systems the proposed orbital architecture features a crossing of the orbital configurations as a result of high eccentricities for one or both of the companions. For such systems, strong mutual gravitational interactions are expected, resulting in catastrophic orbital instabilities, or collisions between the proposed components, on very short timescales. Aims: We re-examine the primary and secondary eclipse timings of the short-period and semi-detached binary RZ Draconis (RZ Dra). The proposed companions were reported to have masses of around ≃0.07 and ≃0.18 M⊙ with the inner companion on an orbit with moderate eccentricity (0.46), whose apocenter distance crosses the orbit of the outer companion. We show that the companions proposed previously follow highly unstable orbits. In an attempt to find a stable system we searched the underlying χ2 parameter space for a best-fit model and carried out an orbit-stability study to test possible best-fit models. If the binary period changes are truly due to additional massive companions in a hierarchical configuration, they must follow stable orbits. Methods: For numerical orbital stability calculations we used well established orbit integration routines. Computations were carried out using a large-scale multi-CPU computing environment. Our data analysis of times of primary and secondary eclipse is based on the Levenberg-Marquardt least-squares minimization algorithm using the two-body Keplerian light-travel time effect model. Results: Despite the wide variety of potential models tested for the RZ Dra system in this work, we found very few models that were stable for even one million years, with the vast majority of systems tested falling apart on

  1. DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

    SciTech Connect

    Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

    2013-12-01

    Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot {sub o} (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ{sub *} of the cluster: N-dot {sub o}=αρ{sub ⋆}, with α = (23 ± 5) × 10{sup –6} pc{sup 3} Myr{sup –1}. For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F {sub ν} (4.4 μm) ≈4 × 10{sup 2} nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration.

  2. Rotation periods and seismic ages of KOIs - comparison with stars without detected planets from Kepler observations

    NASA Astrophysics Data System (ADS)

    Ceillier, T.; van Saders, J.; García, R. A.; Metcalfe, T. S.; Creevey, O.; Mathis, S.; Mathur, S.; Pinsonneault, M. H.; Salabert, D.; Tayar, J.

    2016-02-01

    One of the most difficult properties to derive for stars is their age. For cool main-sequence stars, gyrochronology relations can be used to infer stellar ages from measured rotation periods and Hertzsprung Russell diagram positions. These relations have few calibrators with known ages for old, long rotation period stars. There is a significant sample of old Kepler objects of interest, or KOIs, which have both measurable surface rotation periods and precise asteroseismic measurements from which ages can be accurately derived. In this work, we determine the age and the rotation period of solar-like pulsating KOIs to both compare the rotation properties of stars with and without known planets and enlarge the gyrochronology calibration sample for old stars. We use Kepler photometric light curves to derive the stellar surface rotation periods while ages are obtained with asteroseismology using the Asteroseismic Modelling Portal in which individual mode frequencies are combined with high-resolution spectroscopic parameters. We thus determine surface rotation periods and ages for 11 planet-hosting stars, all over 2 Gyr old. We find that the planet-hosting stars exhibit a rotational behaviour that is consistent with the latest age-rotation models and similar to the rotational behaviour of stars without detected planets. We conclude that these old KOIs can be used to test and calibrate gyrochronology along with stars not known to host planets.

  3. Modelling circumbinary protoplanetary disks. II. Gas disk feedback on planetesimal dynamical and collisional evolution in the circumbinary systems Kepler-16 and 34

    NASA Astrophysics Data System (ADS)

    Lines, S.; Leinhardt, Z. M.; Baruteau, C.; Paardekooper, S.-J.; Carter, P. J.

    2016-05-01

    Aims: We investigate the feasibility of planetesimal growth in circumbinary protoplanetary disks around the observed systems Kepler-16 and Kepler-34 under the gravitational influence of a precessing eccentric gas disk. Methods: We embed the results of our previous hydrodynamical simulations of protoplanetary disks around binaries into an N-body code to perform 3D, high-resolution, inter-particle gravity-enabled simulations of planetesimal growth and dynamics that include the gravitational force imparted by the gas. Results: Including the full, precessing asymmetric gas disk generates high eccentricity orbits for planetesimals orbiting at the edge of the circumbinary cavity, where the gas surface density and eccentricity have their largest values. The gas disk is able to efficiently align planetesimal pericenters in some regions leading to phased, non-interacting orbits. Outside of these areas eccentric planetesimal orbits become misaligned and overlap leading to crossing orbits and high relative velocities during planetesimal collisions. This can lead to an increase in the number of erosive collisions that far outweighs the number of collisions that result in growth. Gravitational focusing from the static axisymmetric gas disk is weak and does not significantly alter collision outcomes from the gas free case. Conclusions: Due to asymmetries in the gas disk, planetesimals are strongly perturbed onto highly eccentric orbits. Where planetesimals orbits are not well aligned, orbit crossings lead to an increase in the number of erosive collisions. This makes it difficult for sustained planetesimal accretion to occur at the location of Kepler-16b and Kepler-34b and we therefore rule out in situ growth. This adds further support to our initial suggestions that most circumbinary planets should form further out in the disk and migrate inwards.

  4. Near-Term Prospects for Extra-Solar Planet Detection: The Astrometric Imaging Telescope

    NASA Astrophysics Data System (ADS)

    Terrile, Richard J.; Levy, Eugene H.; Gatewood, George D.

    The Astrometric Imaging Telescope (AIT) is a 1.5 to 2 meter diameter space-based telescope designed to carry out a comprehensive program of direct and indirect extra-solar planet detection. The telescope consists of two separate instruments, an astrometric experiment to measure the reflex motion of the parent stars and an imaging coronagraph to directly image planets and the circumstellar region. The astrometric technique utilizes the Multichannel Astrometric Photometer (MAP) which passes a Ronchi ruling over a field of stars and measures the centroid of the stars in two orthogonal observations. Used above the Earth's atmosphere this will be about two orders of magnitude more accurate than any existing astrometric instrument and will achieve an accuracy of about 10 microarcseconds. This will allow detection and study of Uranus-size or larger planets in Jovian orbits around several hundred nearby stars. The astrometric study of a parent star of a planetary system will lead to an accurate determination of its distance. The distance is inversely proportional to the magnitude of the annual parallactic motion. The same study yields the major characteristics of the individual bodies within the planetary system. The periods of the orbits are obtained from the analysis of the motions of the central star. Thy are directly related to the distances between the individual planets in the system and the system's sun. The distances in turn determine the thermal radiation level, or effective temperature, at the planet's orbit. With sufficient precision and time, the analysis of the apparent motion of the target star will also yield the eccentricities and the relative inclinations of the orbits of each of the planetary bodies. Assuming the mass of the primary star can be accurately estimated, the study will also yield the mass of each planet.

  5. The Impact of Stellar Rotation on the Detectability of Habitable Planets around M Dwarfs

    NASA Astrophysics Data System (ADS)

    Newton, Elisabeth R.; Irwin, Jonathan; Charbonneau, David; Berta-Thompson, Zachory K.; Dittmann, Jason A.

    2016-04-01

    Stellar activity and rotation frustrate the detection of exoplanets through the radial velocity technique. This effect is particularly of concern for M dwarfs, which can remain magnetically active for billions of years. We compile rotation periods for late-type stars and for the M dwarf planet-host sample in order to investigate the rotation periods of older field stars across the main sequence. We show that for stars with masses between 0.25 and 0.5 {M}ȯ (M4V–M1V), the stellar rotation period typical of field stars coincides with the orbital periods of planets in the habitable zone. This will pose a fundamental challenge to the discovery and characterization of potentially habitable planets around early M dwarfs. Due to the longer rotation periods reached by mid M dwarfs and the shorter orbital period at which the planetary habitable zone is found, stars with masses between 0.1 and 0.25 {M}ȯ (M6V–M4V) offer better opportunities for the detection of habitable planets via radial velocities.

  6. Relevance of oxygen and ozone detections in the search for primitive life in extra solar planets

    NASA Astrophysics Data System (ADS)

    Leger, A.; Pirre, M.; Marceau, F. J.

    1994-06-01

    Considering the future importance of the search for evidences of primitive life on a distant planet, we have revisited some points of the O2 and O3 detection criteria. The budget of free oxygen and organic carbon on Earth is studied. If one includes the organic carbon in sediments, it confirms that O2 is a very reactive gas whose massive presence in a telluric planet atmosphere implies a continuous production. Its detection would be a strong indication for photosynthetic activity, provides the planet is not in a runaway green-house phase. In principle, the direct detection of O2 could be possible in the visible flux of the planet at 760 nm (oxygen A-band) but it would be extremely difficult, considering the much larger flux from the star. The alternative search for the 9.7 micrometers absorption of O3 may be easier as the contrast with the star is increased by 3 orders of magnitude. A simple atmospheric model indicates that the O3 column density is not a linear tracer of the atmospheric O2 content. However, the detection of a substantial O3 absorption (tau greater than 25%) would indicate, within the validity of this model, a O2 ground pressure larger than 10 mbar. The question is raised of whether this pressure is sufficient to indicate a photosynthetic origin of the oxygen. If the answer was positive, it would be an even more sensitive test of photosynthetic activity than the detection of the oxygen A-band. Further studies of these points are clearly needed before determining an observation strategy.

  7. Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveys

    SciTech Connect

    Chung, Sun-Ju; Lee, Chung-Uk; Koo, Jae-Rim E-mail: leecu@kasi.re.kr

    2014-04-20

    Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over its peak, confident planet detection did not happen due to extremely weak central perturbations (EWCPs, fractional deviations of ≲ 2%). For confident detection of planets in EWCP events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems. The next-generation ground-based observation project, Korea Microlensing Telescope Network (KMTNet), satisfies these conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of ≤2% in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of >50% in the case of ≲ 100 M {sub E} planets with separations of 0.2 AU ≲ d ≲ 20 AU. We find that for main-sequence and sub-giant source stars, ≳ 1 M {sub E} planets in EWCP events with deviations ≤2% can be detected with frequency >50% in a certain range that changes with the planet mass. However, it is difficult to detect planets in EWCP events of bright stars like giant stars because it is easy for KMTNet to be saturated around the peak of the events because of its constant exposure time. EWCP events are caused by close, intermediate, and wide planetary systems with low-mass planets and close and wide planetary systems with massive planets. Therefore, we expect that a much greater variety of planetary systems than those already detected, which are mostly intermediate planetary systems, regardless of the planet mass, will be significantly detected in the near future.

  8. Exoplanet detection. A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary.

    PubMed

    Gould, A; Udalski, A; Shin, I-G; Porritt, I; Skowron, J; Han, C; Yee, J C; Kozłowski, S; Choi, J-Y; Poleski, R; Wyrzykowski, Ł; Ulaczyk, K; Pietrukowicz, P; Mróz, P; Szymański, M K; Kubiak, M; Soszyński, I; Pietrzyński, G; Gaudi, B S; Christie, G W; Drummond, J; McCormick, J; Natusch, T; Ngan, H; Tan, T-G; Albrow, M; DePoy, D L; Hwang, K-H; Jung, Y K; Lee, C-U; Park, H; Pogge, R W; Abe, F; Bennett, D P; Bond, I A; Botzler, C S; Freeman, M; Fukui, A; Fukunaga, D; Itow, Y; Koshimoto, N; Larsen, P; Ling, C H; Masuda, K; Matsubara, Y; Muraki, Y; Namba, S; Ohnishi, K; Philpott, L; Rattenbury, N J; Saito, To; Sullivan, D J; Sumi, T; Suzuki, D; Tristram, P J; Tsurumi, N; Wada, K; Yamai, N; Yock, P C M; Yonehara, A; Shvartzvald, Y; Maoz, D; Kaspi, S; Friedmann, M

    2014-07-01

    Using gravitational microlensing, we detected a cold terrestrial planet orbiting one member of a binary star system. The planet has low mass (twice Earth's) and lies projected at ~0.8 astronomical units (AU) from its host star, about the distance between Earth and the Sun. However, the planet's temperature is much lower, <60 Kelvin, because the host star is only 0.10 to 0.15 solar masses and therefore more than 400 times less luminous than the Sun. The host itself orbits a slightly more massive companion with projected separation of 10 to 15 AU. This detection is consistent with such systems being very common. Straightforward modification of current microlensing search strategies could increase sensitivity to planets in binary systems. With more detections, such binary-star planetary systems could constrain models of planet formation and evolution. PMID:24994642

  9. Detection of a Neptune-Mass Planet in the ρ1 Cancri System Using the Hobby-Eberly Telescope

    NASA Astrophysics Data System (ADS)

    McArthur, Barbara E.; Endl, Michael; Cochran, William D.; Benedict, G. Fritz; Fischer, Debra A.; Marcy, Geoffrey W.; Butler, R. Paul; Naef, Dominique; Mayor, Michel; Queloz, Diedre; Udry, Stephane; Harrison, Thomas E.

    2004-10-01

    We report the detection of the lowest mass extrasolar planet yet found around a Sun-like star-a planet with an Msini of only 14.21+/-2.91 M⊕ in an extremely short period orbit (P=2.808 days) around ρ1 Cancri, a planetary system that already has three known planets. Velocities taken from late 2003-2004 at McDonald Observatory with the Hobby-Eberly Telescope revealed this inner planet at 0.04 AU. We estimate an inclination of the outer planet ρ1 Cancri d, based on Hubble Space Telescope Fine Guidance Sensor measurements that suggest an inner planet of only 17.7+/-5.57 M⊕, if coplanarity is assumed for the system.

  10. Toward detection of terrestrial planets in the habitable zone of our closest neighbor: proxima Centauri

    NASA Astrophysics Data System (ADS)

    Endl, M.; Kürster, M.

    2008-09-01

    Context: The precision of radial velocity (RV) measurements to detect indirectly planetary companions of nearby stars has improved to enable the discovery of extrasolar planets in the Neptune and Super-Earth mass range. Detections of extremely low mass planets, even as small as 1 Earth mass or below, in short-period orbits now appears conceivable in ongoing RV planet searches. Discoveries of these Earth-like planets by means of ground-based RV programs will help to determine the parameter η⊕, the frequency of potentially habitable planets around other stars. Aims: In search of low-mass planetary companions we monitored Proxima Centauri (M5V) as part of our M dwarf program. In the absence of a significant detection, we use these data to demonstrate the general capability of the RV method in finding terrestrial planets. For late M dwarfs the classic liquid surface water habitable zone (HZ) is located close to the star, in which circumstances the RV method is most effective. We want to demonstrate that late M dwarfs are ideal targets for the search of terrestrial planets with the RV technique. Methods: Using the iodine cell technique we obtained differential RV measurements of Proxima Cen over a time span of 7 years with the UVES spectrograph at the ESO VLT. We determine upper limits to the masses of companions in circular orbits by means of numerical simulations. Results: The RV data of Proxima Cen have a total rms scatter of 3.1~m s-1 and a period search does not reveal any significant signals. In contrast to our earlier results for Barnard's star, the RV results for the active M dwarf Proxima Cen are only weakly correlated with Hα line index measurements. As a result of our companion limit calculations, we find that we successfully recover all test signals with RV amplitudes corresponding to planets with m sin i ≥ 2-3 M_⊕ residing inside the HZ of Proxima Cen with a statistical significance of >99%. Over the same period range, we can recover 50% of the test

  11. WISE Detections of Dust in the Habitable Zones of Planet-bearing Stars

    NASA Astrophysics Data System (ADS)

    Morales, Farisa Y.; Padgett, D. L.; Bryden, G.; Werner, M. W.; Furlan, E.

    2012-09-01

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 μm (T dust ~ 300 and/or ~150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopaedia as of 2012 January 31, 350 are robustly detected by WISE at >=5σ level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 μm at >=3σ level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of ~2.6% for stars of all evolutionary stages, but ~1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  12. WISE Detections of Dust in the Habitable Zones of Planet-bearing Stars

    NASA Astrophysics Data System (ADS)

    Morales, Farisa Y.; Padgett, D.; Bryden, G.; Werner, M. W.; Furlan, E.

    2013-01-01

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 micron (T_dust ~300 and/or ~150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopaedia as of January 31, 2012, 350 are robustly detected by WISE at 5-sigma level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to conrm bona fide point sources. We find 9 planet bearing stars show dust excess emission at 12 and/or 22 micron at 3-sigma level around young, main sequence, or evolved giant stars. Overall, our results yield an excess incidence of 2.6% for stars of all evolutionary stages, but 1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  13. WISE Detections of Dust in the Habitable Zones of Planet-Bearing Stars

    NASA Technical Reports Server (NTRS)

    Morales, Farisa Y.; Padgett, Deborah L.; Bryden, Geoffrey; Werner, M. W.; Furlan, E.

    2012-01-01

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 microns (T(sub dust) approx.300 and/or approx.150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopedia as of 2012 January 31, 350 are robustly detected by WISE at > or = 5(sigma) level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 microns at > or = 3(sigma) level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of approx.2.6% for stars of all evolutionary stages, but approx.1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  14. WISE DETECTIONS OF DUST IN THE HABITABLE ZONES OF PLANET-BEARING STARS

    SciTech Connect

    Morales, Farisa Y.; Bryden, G.; Werner, M. W.; Padgett, D. L.; Furlan, E.

    2012-09-20

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 {mu}m (T{sub dust} {approx} 300 and/or {approx}150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopaedia as of 2012 January 31, 350 are robustly detected by WISE at {>=}5{sigma} level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 {mu}m at {>=}3{sigma} level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of {approx}2.6% for stars of all evolutionary stages, but {approx}1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  15. The detection of dust around NN Ser

    NASA Astrophysics Data System (ADS)

    Hardy, Adam; Schreiber, Matthias R.; Parsons, Steven G.; Caceres, Claudio; Brinkworth, Carolyn; Veras, Dimitri; Gänsicke, Boris T.; Marsh, Thomas R.; Cieza, Lucas

    2016-07-01

    Eclipse timing variations observed from the post-common-envelope binary (PCEB) NN Ser offer strong evidence in favour of circumbinary planets existing around PCEBs. If real, these planets may be accompanied by a disc of dust. We here present the ALMA detection of flux at 1.3 mm from NN Ser, which is likely due to thermal emission from a dust disc of mass ˜0.8 ± 0.2 M⊕. We performed simulations of the history of NN Ser to determine possible origins of this dust, and conclude that the most likely origin is, in fact, common-envelope material which was not expelled from the system and instead formed a circumbinary disc. These discs have been predicted by theory but previously remained undetected. While the presence of this dust does not prove the existence of planets around NN Ser, it adds credibility to the possibility of planets forming from common-envelope material in a `second-generation' scenario.

  16. The Detection of Dust around NN Ser

    NASA Astrophysics Data System (ADS)

    Hardy, Adam; Schreiber, Matthias R.; Parsons, Steven G.; Caceres, Claudio; Brinkworth, Carolyn; Veras, Dimitri; Gänsicke, Boris T.; Marsh, Thomas R.; Cieza, Lucas

    2016-04-01

    Eclipse timing variations observed from the post common-envelope binary (PCEB) NN Ser offer strong evidence in favour of circumbinary planets existing around PCEBs. If real, these planets may be accompanied by a disc of dust. We here present the ALMA detection of flux at 1.3 mm from NN Ser, which is likely due to thermal emission from a dust disc of mass ˜0.8 ± 0.2 M⊕. We performed simulations of the history of NN Ser to determine possible origins of this dust, and conclude that the most likely origin is, in fact, common-envelope material which was not expelled from the system and instead formed a circumbinary disc. These discs have been predicted by theory but previously remained undetected. While the presence of this dust does not prove the existence of planets around NN Ser, it adds credibility to the possibility of planets forming from common-envelope material in a `second-generation' scenario.

  17. DETECTABILITY OF EARTH-LIKE PLANETS IN CIRCUMSTELLAR HABITABLE ZONES OF BINARY STAR SYSTEMS WITH SUN-LIKE COMPONENTS

    SciTech Connect

    Eggl, Siegfried; Pilat-Lohinger, Elke; Haghighipour, Nader

    2013-02-20

    Given the considerable percentage of stars that are members of binaries or stellar multiples in the solar neighborhood, it is expected that many of these binaries host planets, possibly even habitable ones. The discovery of a terrestrial planet in the {alpha} Centauri system supports this notion. Due to the potentially strong gravitational interaction that an Earth-like planet may experience in such systems, classical approaches to determining habitable zones (HZ), especially in close S-type binary systems, can be rather inaccurate. Recent progress in this field, however, allows us to identify regions around the star permitting permanent habitability. While the discovery of {alpha} Cen Bb has shown that terrestrial planets can be detected in solar-type binary stars using current observational facilities, it remains to be shown whether this is also the case for Earth analogs in HZs. We provide analytical expressions for the maximum and rms values of radial velocity and astrometric signals, as well as transit probabilities of terrestrial planets in such systems, showing that the dynamical interaction of the second star with the planet may indeed facilitate the planets' detection. As an example, we discuss the detectability of additional Earth-like planets in the averaged, extended, and permanent HZs around both stars of the {alpha} Centauri system.

  18. A maximum entropy approach to detect close-in giant planets around active stars

    NASA Astrophysics Data System (ADS)

    Petit, P.; Donati, J.-F.; Hébrard, E.; Morin, J.; Folsom, C. P.; Böhm, T.; Boisse, I.; Borgniet, S.; Bouvier, J.; Delfosse, X.; Hussain, G.; Jeffers, S. V.; Marsden, S. C.; Barnes, J. R.

    2015-12-01

    Context. The high spot coverage of young active stars is responsible for distortions of spectral lines that hamper the detection of close-in planets through radial velocity methods. Aims: We aim to progress towards more efficient exoplanet detection around active stars by optimizing the use of Doppler imaging in radial velocity measurements. Methods: We propose a simple method to simultaneously extract a brightness map and a set of orbital parameters through a tomographic inversion technique derived from classical Doppler mapping. Based on the maximum entropy principle, the underlying idea is to determine the set of orbital parameters that minimizes the information content of the resulting Doppler map. We carry out a set of numerical simulations to perform a preliminary assessment of the robustness of our method, using an actual Doppler map of the very active star HR 1099 to produce a realistic synthetic data set for various sets of orbital parameters of a single planet in a circular orbit. Results: Using a simulated time series of 50 line profiles affected by a peak-to-peak activity jitter of 2.5 km s-1, in most cases we are able to recover the radial velocity amplitude, orbital phase, and orbital period of an artificial planet down to a radial velocity semi-amplitude of the order of the radial velocity scatter due to the photon noise alone (about 50 m s-1 in our case). One noticeable exception occurs when the planetary orbit is close to co-rotation, in which case significant biases are observed in the reconstructed radial velocity amplitude, while the orbital period and phase remain robustly recovered. Conclusions: The present method constitutes a very simple way to extract orbital parameters from heavily distorted line profiles of active stars, when more classical radial velocity detection methods generally fail. It is easily adaptable to most existing Doppler imaging codes, paving the way towards a systematic search for close-in planets orbiting young, rapidly

  19. Exoplanet detection. Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581.

    PubMed

    Robertson, Paul; Mahadevan, Suvrath; Endl, Michael; Roy, Arpita

    2014-07-25

    The M dwarf star Gliese 581 is believed to host four planets, including one (GJ 581d) near the habitable zone that could possibly support liquid water on its surface if it is a rocky planet. The detection of another habitable-zone planet--GJ 581g--is disputed, as its significance depends on the eccentricity assumed for d. Analyzing stellar activity using the Hα line, we measure a stellar rotation period of 130 ± 2 days and a correlation for Hα modulation with radial velocity. Correcting for activity greatly diminishes the signal of GJ 581d (to 1.5 standard deviations) while significantly boosting the signals of the other known super-Earth planets. GJ 581d does not exist, but is an artifact of stellar activity which, when incompletely corrected, causes the false detection of planet g. PMID:24993348

  20. The Rossiter-McLaughlin effect of planets transiting M-dwarfs, and its impact on planet detection in Doppler surveys

    NASA Astrophysics Data System (ADS)

    Cloutier, Ryan; Triaud, Amaury H. M. J.; Menou, Kristen

    2015-12-01

    A major endeavour in recent exoplanetary science is to detect potentially habitable, Earth-like planets around nearby stars. The upcoming SPIRou (Le SpectroPolarimètre Infra-Rouge) Legacy Survey is one such initiative and is optimized for the detection of such exoplanets around cool M-dwarfs via the radial velocity method. If a planetary transit occurs, radial velocity observations made in-transit will be subject to an anomalous signal due to the occultation of the differentially Doppler shifted stellar limbs; the so-called Rossiter-McLaughlin (RM) effect. Using the SPIRou Legacy Survey as a test case, we assess the impact of the RM effect on unevenly sampled Doppler survey data. Firstly, the stellar spectra taken during a Doppler survey, along with an assumed planetary mass-radius relationship, can be used to estimate the likelihood of a planetary transit. This is useful for target-selection of stars with potentially transiting exoplanets. However, if not properly accounted for in models of the stellar Doppler shift, the anomalous RM effect can result in 20-30% loss in planet detection rate. This significant loss can be easily remedied by our proposed simple process of iteratively re-sampling the timeseries and searching for periodicities. For the subset of the anticipated SPIRou planet population that is hidden by the RM effect, our algorithm is capable of recovering planets with the same efficiency as in the absence of the RM effect thus negating its effect.

  1. Possible planet formation in the young, low-mass, multiple stellar system GG Tau A.

    PubMed

    Dutrey, Anne; Di Folco, Emmanuel; Guilloteau, Stéphane; Boehler, Yann; Bary, Jeff; Beck, Tracy; Beust, Hervé; Chapillon, Edwige; Gueth, Fredéric; Huré, Jean-Marc; Pierens, Arnaud; Piétu, Vincent; Simon, Michal; Tang, Ya-Wen

    2014-10-30

    The formation of planets around binary stars may be more difficult than around single stars. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumstellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star systems. A circumbinary disk was discovered around the young low-mass binary system GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple system. It has one large inner disk around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity, but other than a single weak detection, the distribution of cold gas in this cavity or in any other binary or multiple star system has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations. PMID:25355359

  2. Photometric detection of extrasolar planets using L.S.T.-type telescopes

    NASA Technical Reports Server (NTRS)

    Fennelly, A. J.; Matloff, G. L.; Frye, G.

    1975-01-01

    Detection of planets similar to the earth and Jupiter that might be circling nearby stars is possible with the large space telescope (LST), or modifications of this instrument. The use of the moon as an occulter to increase the signal-to-noise ratio and the expected photon fluxes from hypothetical planetary companions to alpha Centauri A and B, tau Ceti, and epsilon Eridani are discussed. Because Barnard's Star is a red dwarf of visual apparent magnitude 9.5, photometric detection of its hypothetical Jupiter-like companion would be difficult using the LST-occulter system described in this paper.

  3. Ground-based detectability of terrestrial and Jovian extrasolar planets: observations of CM Draconis at Lick Observatory

    NASA Technical Reports Server (NTRS)

    Doyle, L. R.; Dunham, E. T.; Deeg, H. J.; Blue, J. E.; Jenkins, J. M.

    1996-01-01

    The detection of terrestrial-sized extrasolar planets from the ground has been thought to be virtually impossible due to atmospheric scintillation limits. However, we show that this is not the case especially selected (but nevertheless main sequence) stars, namely small eclipsing binaries. For the smallest of these systems, CM Draconis, several months to a few years of photometric observations with 1-m-class telescopes will be sufficient to detect the transits of any short-period planets of sizes > or = 1.5 Earth radii (RE), using cross-correlation analysis with moderately good photometry. Somewhat larger telescopes will be needed to extend this detectability to terrestrial planets in larger eclipsing binary systems. (We arbitrarily define "terrestrial planets" herein as those whose disc areas are closer to that of Earth's than Neptune's i.e., less than about 2.78 RE.) As a "spin-off" of such observations, we will also be able to detect the presence of Jovian-mass planets without transits using the timing of the eclipse minima. Eclipse minima will drift in time as the binary system is offset by a sufficiently massive planet (i.e., one Jupiter mass) about the binary/giant-planet barycenter, causing a periodic variation in the light travel time to the observer. We present here an outline of present observations taking place at the University of California Lick Observatory using the Crossley 0.9-m telescope in collaboration with other observatories (in South Korea, Crete, France, Canary Islands, and New York) to detect or constrain the existence of terrestrial planets around main sequence eclipsing binary star systems, starting with CM Draconis. We demonstrate the applicability of photometric data to the general detection of gas giant planets via eclipse minima timings in many other small-mass eclipsing binary systems as well.

  4. Interactions between planets and evolved stars

    NASA Astrophysics Data System (ADS)

    Shengbang, Qian; Zhongtao, Han; Fernández Lajús, E.; liying, Zhu; Wenping, Liao; Miloslav, Zejda; Linjia, Li; Voloshina, Irina; Liang, Liu; Jiajia., He

    2016-07-01

    Searching for planetary companions to evolved stars (e.g., white dwarfs (WD) and Cataclysmic Variables (CV)) can provide insight into the interaction between planets and evolved stars as well as on the ultimate fate of planets. We have monitored decades of CVs and their progenitors including some detached WD binaries since 2006 to search for planets orbiting these systems. In the present paper, we will show some observational results of circumbinary planets in orbits around CVs and their progenitors. Some of our findings include planets with the shortest distance to the central evolved binaries and a few multiple planetary systems orbiting binary stars. Finally, by comparing the observational properties of planetary companions to single WDs and WD binaries, the interaction between planets and evolved stars and the ultimate fate of planets are discussed.

  5. Astrometric Detection of Extrasolar Planets: Results of a Feasibility Study with the Palomar 5 Meter Telescope

    NASA Technical Reports Server (NTRS)

    Pravdo, Steven H.; Shaklan, Stuart B.

    1996-01-01

    The detection of extrasolar planets around stars like the Sun remains an important goal of astronomy. We present results from Palomar 5 m observations of the open cluster NGC 2420 in which we measure some of the sources of noise that will be present in an astrometric search for extrasolar planets. This is the first time that such a large aperture has been used for high-precision astrometry. We find that the atmospheric noise is 150 micro-arcsec hr(exp 1/2) across a 90 sec field of view and that differential chromatic refraction (DCR) can be calibrated to 128 micro-arcsec for observations within 1 hr of the meridian and 45 deg of zenith. These results confirm that a model for astrometric measurements can be extrapolated to large apertures. We demonstrate, based upon these results, that a large telescope achieves the sensitivity required to perform a statistically significant search for extra solar planets. We describe an astrometric technique to detect planets, the astrometric signals expected, the role of reference stars, and the sources of measurement noise: photometric noise, atmospheric motion between stars, sky background, instrumental noise, and DCR. For the latter, we discuss a method to reduce the noise further to 66 micro-arcsecond for observations within 1 hr of the meridian and 45 deg of zenith. We discuss optimal lists of target stars taken from the latest Gliese & Jahreiss catalog of nearby stars with the largest potential astrometric signals, declination limits for both telescope accessibility and reduced DCR, and galactic latitude limits for a sufficiant number of reference stars. Two samples are described from which one can perform statistically significant searches for gas giant planets around nearby stars. One sample contains 100 "solar class" stars with an average stellar mass of 0.82 solar mass; the other maximizes the number of stars, 574, by searching mainly low-mass M stars. We perform Monte Carlo simulations of the statistical significance of

  6. Planetfinder: An Online Interactive Module for Learning How Astronomers Detect Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    McCray, Richard

    Planetfinder is a Web-based module designed to enable undergraduates to learn how astronomers detect extrasolar planets through observations of the Doppler shifts of a star's spectral lines. The module guides students through the process of measuring the masses and orbital parameters of actual extrasolar planets by fitting model Doppler curves to the data. The main goal of the exercise is to give students an understanding of the process of scientific measurement and model fitting. The exercise can be done at various levels of difficulty, ranging from measuring the properties of planetary systems having nearly circular orbits without using algebra, to exploring properties of systems having eccentric orbits and the associated equations of motion. The module is self-checking. Student work is stored in a database that is easily accessible by the instructor. The module has been tested at several institutions and is available for public use.

  7. Extrasolar planets

    PubMed Central

    Lissauer, Jack J.; Marcy, Geoffrey W.; Ida, Shigeru

    2000-01-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

  8. Extrasolar planets.

    PubMed

    Lissauer, J J; Marcy, G W; Ida, S

    2000-11-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

  9. {chi}{sup 2} DISCRIMINATORS FOR TRANSITING PLANET DETECTION IN KEPLER DATA

    SciTech Connect

    Seader, Shawn; Tenenbaum, Peter; Jenkins, Jon M.; Burke, Christopher J. E-mail: peter.tenenbaum@nasa.gov E-mail: christopher.j.burke@nasa.gov

    2013-06-01

    The Kepler spacecraft observes a host of target stars to detect transiting planets. Requiring a 7.1{sigma} detection in three years of data yields over 100,000 detections, many of which are false alarms. After a second cut is made on a robust detection statistic, some 50,000 or more targets still remain. These false alarms waste resources as they propagate through the remainder of the software pipeline and so a method to discriminate against them is crucial in maintaining the desired sensitivity to true events. This paper describes a {chi}{sup 2} test which represents a novel application of an existing formalism developed for false alarm mitigation in searches for gravitational waves. Using this technique, the false alarm rate can be lowered to {approx}5%.

  10. Ground-based direct detection of close-in extra-solar planets with nulling and high order adaptive optics

    NASA Astrophysics Data System (ADS)

    Langlois, M.; Burrows, A.; Hinz, P.

    2006-01-01

    Ground-based direct detection of extra-solar planets is very challenging due to high planet to star brightness contrasts. For giant close-in planets, such as have been discovered by the radial velocity method, closer than 0.1 AU, the reflected light is predicted to be fairly high yielding a contrast ratio ranging from 10-4 to 10-5 at near infra-red wavelengths. In this paper, we investigate direct detection of reflected light from such planets using nulling interferometry, and high-order adaptive optics in conjunction with large double aperture ground-based telescopes. In this configuration, at least 10-3 suppression of the entire stellar Airy pattern with small loss of planet flux as close as 0.03 arcsec is achievable. Distinguishing residual starlight from the planet signal is achieved by using the center of gravity shift method or multicolor differential imaging. Using these assumptions, we derive exposure times from a few minutes to several hours for direct detection of many of the known extra-solar planets with several short-baseline double aperture telescopes such as the Large Binocular Telescope (LBT), the Very Large Telescope (VLT) and the Keck Telescope.

  11. The minimum mass of detectable planets in protoplanetary discs and the derivation of planetary masses from high-resolution observations

    PubMed Central

    Rosotti, Giovanni P.; Juhasz, Attila; Booth, Richard A.; Clarke, Cathie J.

    2016-01-01

    We investigate the minimum planet mass that produces observable signatures in infrared scattered light and submillimetre (submm) continuum images and demonstrate how these images can be used to measure planet masses to within a factor of about 2. To this end, we perform multi-fluid gas and dust simulations of discs containing low-mass planets, generating simulated observations at 1.65, 10 and 850 μm. We show that the minimum planet mass that produces a detectable signature is ∼15 M⊕: this value is strongly dependent on disc temperature and changes slightly with wavelength (favouring the submm). We also confirm previous results that there is a minimum planet mass of ∼20 M⊕ that produces a pressure maximum in the disc: only planets above this threshold mass generate a dust trap that can eventually create a hole in the submm dust. Below this mass, planets produce annular enhancements in dust outwards of the planet and a reduction in the vicinity of the planet. These features are in steady state and can be understood in terms of variations in the dust radial velocity, imposed by the perturbed gas pressure radial profile, analogous to a traffic jam. We also show how planet masses can be derived from structure in scattered light and submm images. We emphasize that simulations with dust need to be run over thousands of planetary orbits so as to allow the gas profile to achieve a steady state and caution against the estimation of planet masses using gas-only simulations. PMID:27279783

  12. The minimum mass of detectable planets in protoplanetary discs and the derivation of planetary masses from high-resolution observations

    NASA Astrophysics Data System (ADS)

    Rosotti, Giovanni P.; Juhasz, Attila; Booth, Richard A.; Clarke, Cathie J.

    2016-07-01

    We investigate the minimum planet mass that produces observable signatures in infrared scattered light and submillimetre (submm) continuum images and demonstrate how these images can be used to measure planet masses to within a factor of about 2. To this end, we perform multi-fluid gas and dust simulations of discs containing low-mass planets, generating simulated observations at 1.65, 10 and 850 μm. We show that the minimum planet mass that produces a detectable signature is ˜15 M⊕: this value is strongly dependent on disc temperature and changes slightly with wavelength (favouring the submm). We also confirm previous results that there is a minimum planet mass of ˜20 M⊕ that produces a pressure maximum in the disc: only planets above this threshold mass generate a dust trap that can eventually create a hole in the submm dust. Below this mass, planets produce annular enhancements in dust outwards of the planet and a reduction in the vicinity of the planet. These features are in steady state and can be understood in terms of variations in the dust radial velocity, imposed by the perturbed gas pressure radial profile, analogous to a traffic jam. We also show how planet masses can be derived from structure in scattered light and submm images. We emphasize that simulations with dust need to be run over thousands of planetary orbits so as to allow the gas profile to achieve a steady state and caution against the estimation of planet masses using gas-only simulations.

  13. Application of super smooth optics to extra-solar planet detection

    NASA Technical Reports Server (NTRS)

    Terrile, Richard J.; Ftaclas, Christ

    1989-01-01

    The observational constraints on direct detection of extrasolar planets around nearby stars are defined. The design of an instrument capable of meeting these goals requires the efficient reduction of diffracted and scattered light by about three orders of magnitude below the airy wings of the unapodized aperture. The diffraction reduction is achieved through the high-efficiency coronagraph, which uses Gaussian occulting masks in the first focus to concentrate better diffracted light in the pupil plane. Laboratory experiments confirm this high efficiency to the limits set by the experimental setup. Scattering due to midspatial scale figure error in the mirrors must also be reduced to a comparable level.

  14. Beyond the Wobbles: Teaching Students About Detecting Planets with the Transit and Gravitational Microlensing Methods

    NASA Astrophysics Data System (ADS)

    Prather, Edward E.; Wallace, Colin Scott; Chambers, Timothy G.; Brissenden, Gina; Traub, Wesley A.; Greene, W. M.; Biferno, Anya A.; Rodriguez, Joshua

    2015-01-01

    Members of the Center for Astronomy Education (CAE) at the University of Arizona's Steward Observatory in collaboration with JPL scientists, visualization experts, and education and public outreach professionals with the Exoplanet Exploration Program (ExEP) have recently completed classroom field-testing of a new suite of educational materials to help learners better understand how extrasolar planets are detected using the transit and gravitational microlensing techniques. This collaboration has created a set of evidence-based Think-Pair-Share questions, Lecture-Tutorials, animations, presentation slides, and instrucotrs guide that can be used together or separately to actively engage learners in reasoning about the data and scientific representations associated with these exciting new extrasolar planet detection methods. In this talk we present several of the conceptually challenging collaborative learning tasks that students encounter with this new suite of educational materials and some of the assessment questions we are using to assess the efficacy of their use in general education, college-level astronomy courses.

  15. INITIAL CHARACTERISTICS OF KEPLER LONG CADENCE DATA FOR DETECTING TRANSITING PLANETS

    SciTech Connect

    Jenkins, Jon M.; Caldwell, Douglas A.; Chandrasekaran, Hema; Twicken, Joseph D.; Quintana, Elisa V.; Clarke, Bruce D.; Li, Jie; Tenenbaum, Peter; Wu, Hayley; Klaus, Todd C.; Van Cleve, Jeffrey

    2010-04-20

    The Kepler Mission seeks to detect Earth-size planets transiting solar-like stars in its {approx}115 deg{sup 2} field of view over the course of its 3.5 year primary mission by monitoring the brightness of each of {approx}156,000 Long Cadence stellar targets with a time resolution of 29.4 minutes. We discuss the photometric precision achieved on timescales relevant to transit detection for data obtained in the 33.5 day long Quarter 1 (Q1) observations that ended 2009 June 15. The lower envelope of the photometric precision obtained at various timescales is consistent with expected random noise sources, indicating that Kepler has the capability to fulfill its mission. The Kepler light curves exhibit high precision over a large dynamic range, which will surely permit their use for a large variety of investigations in addition to finding and characterizing planets. We discuss the temporal characteristics of both the raw flux time series and the systematic error-corrected flux time series produced by the Kepler Science Pipeline, and give examples illustrating Kepler's large dynamic range and the variety of light curves obtained from the Q1 observations.

  16. Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Wallace, Colin S.; Chambers, Timothy G.; Prather, Edward E.; Brissenden, Gina

    2016-05-01

    The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial called "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.

  17. Imaging the dust sublimation front of a circumbinary disk

    NASA Astrophysics Data System (ADS)

    Hillen, M.; Kluska, J.; Le Bouquin, J.-B.; Van Winckel, H.; Berger, J.-P.; Kamath, D.; Bujarrabal, V.

    2016-04-01

    Aims: We present the first near-IR milli-arcsecond-scale image of a post-AGB binary that is surrounded by hot circumbinary dust. Methods: A very rich interferometric data set in six spectral channels was acquired of IRAS 08544-4431 with the new RAPID camera on the PIONIER beam combiner at the Very Large Telescope Interferometer (VLTI). A broadband image in the H-band was reconstructed by combining the data of all spectral channels using the SPARCO method. Results: We spatially separate all the building blocks of the IRAS 08544-4431 system in our milliarcsecond-resolution image. Our dissection reveals a dust sublimation front that is strikingly similar to that expected in early-stage protoplanetary disks, as well as an unexpected flux signal of ~4% from the secondary star. The energy output from this companion indicates the presence of a compact circum-companion accretion disk, which is likely the origin of the fast outflow detected in Hα. Conclusions: Our image provides the most detailed view into the heart of a dusty circumstellar disk to date. Our results demonstrate that binary evolution processes and circumstellar disk evolution can be studied in detail in space and over time. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 094.D-0865.

  18. Open Source Cloud Computing for Transiting Planet Discovery

    NASA Astrophysics Data System (ADS)

    McCullough, Peter R.; Fleming, Scott W.; Zonca, Andrea; Flowers, Jack; Nguyen, Duy Cuong; Sinkovits, Robert; Machalek, Pavel

    2014-06-01

    We provide an update on the development of the open-source software suite designed to detect exoplanet transits using high-performance and cloud computing resources (https://github.com/openEXO). Our collaboration continues to grow as we are developing algorithms and codes related to the detection of transit-like events, especially in Kepler data, Kepler 2.0 and TESS data when available. Extending the work of Berriman et al. (2010, 2012), we describe our use of the XSEDE-Gordon supercomputer and Amazon EMR cloud to search for aperiodic transit-like events in Kepler light curves. Such events may be caused by circumbinary planets or transiting bodies, either planets or stars, with orbital periods comparable to or longer than the observing baseline such that only one transit is observed. As a bonus, we use the same code to find stellar flares too; whereas transits reduce the flux in a box-shaped profile, flares increase the flux in a fast-rise, exponential-decay (FRED) profile that nevertheless can be detected reliably with a square-wave finder.

  19. Survival of planets around shrinking stellar binaries

    PubMed Central

    Muñoz, Diego J.; Lai, Dong

    2015-01-01

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov–Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

  20. Survival of planets around shrinking stellar binaries.

    PubMed

    Muñoz, Diego J; Lai, Dong

    2015-07-28

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

  1. High-order adaptive optics requirements for direct detection of extrasolar planets: Application to the SPHERE instrument.

    PubMed

    Fusco, T; Rousset, G; Sauvage, J-F; Petit, C; Beuzit, J-L; Dohlen, K; Mouillet, D; Charton, J; Nicolle, M; Kasper, M; Baudoz, P; Puget, P

    2006-08-21

    The detection of extrasolar planets implies an extremely high-contrast, long-exposure imaging capability at near infrared and probably visible wavelengths. We present here the core of any Planet Finder instrument, that is, the extreme adaptive optics (XAO) subsystem. The level of AO correction directly impacts the exposure time required for planet detection. In addition, the capacity of the AO system to calibrate all the instrument static defects ultimately limits detectivity. Hence, the extreme AO system has to adjust for the perturbations induced by the atmospheric turbulence, as well as for the internal aberrations of the instrument itself. We propose a feasibility study for an extreme AO system in the frame of the SPHERE (Spectro-Polarimetry High-contrast Exoplanet Research) instrument, which is currently under design and should equip one of the four VLT 8-m telescopes in 2010. PMID:19529118

  2. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.

    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth's lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  3. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.

    2008-06-01

    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth’s lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  4. Extrasolar Planets and Prospects for Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Fischer, Debra A.

    2004-06-01

    Examination of ˜2000 sun--like stars has revealed 97 planets (as of 2002 Nov), all residing within our Milky Way Galaxy and within ˜200 light years of our Solar System. They have masses between 0.1 and 10 times that of Jupiter, and orbital sizes of 0.05--5 AU. Thus planets occupy the entire detectable domain of mass and orbits. News &summaries about extrasolar planets are provided at: http://exoplanets.org. These planets were all discovered by the wobble of the host stars, induced gravitationally by the planets, causing a periodicity in the measured Doppler effect of the starlight. Earth--mass planets remain undetectable, but space--based missions such as Kepler, COROT and SIM may provide detections of terrestrial planets within the next decade. The number of planets increases with decreasing planet mass, indicating that nature makes more small planets than jupiter--mass planets. Extrapolation, though speculative, bodes well for an even larger number of earth--mass planets. These observations and the theory of planet formation suggests that single sun--like stars commonly harbor earth--sized rocky planets, as yet undetectable. The number of planets increases with increasing orbital distance from the host star, and most known planets reside in non--circular orbits. Many known planets reside in the habitable zone (albeit being gas giants) and most newly discovered planets orbit beyond 1 AU from their star. A population of Jupiter--like planets may reside at 5--10 AU from stars, not easily detectable at present. The sun--like star 55 Cancri harbors a planet of 4--10 Jupiter masses orbiting at 5.5 AU in a low eccentricity orbit, the first analog of our Jupiter, albeit with two large planets orbiting inward. To date, 10 multiple--planet systems have been discovered, with four revealing gravitational interactions between the planets in the form of resonances. GJ 876 has two planets with periods of 1 and 2 months. Other planetary systems are ``hierarchical'', consisting

  5. DETECTABILITY OF EXOPLANETS IN THE {beta} PIC MOVING GROUP WITH THE GEMINI PLANET IMAGER

    SciTech Connect

    Kataria, Tiffany; Simon, Michal

    2010-07-15

    We model the detectability of exoplanets around stars in the {beta} Pic Moving Group (BPMG) using the Gemini Planet Imager (GPI), a coronagraphic instrument designed to detect companions by imaging. Members of the BPMG are considered promising targets for exoplanet searches because of their youth ({approx}12 Myr) and proximity (median distance {approx}35 pc). We wrote a modeling procedure to generate hypothetical companions of given mass, age, eccentricity, and semi-major axis, and place them around BPMG members that fall within the V-band range of the GPI. We count companions lying within the GPI's field of view and H-band fluxes that have a host-companion flux ratio placing them within its sensitivity as possible detections. The fraction of companions that could be detected depends on their brightness at 12 Myr, and hence formation mechanism, and on their distribution of semi-major axes. We used brightness models for formation by disk instability and core-accretion. We considered the two extreme cases of the semi-major axis distribution-the log-normal distribution of the nearby F- and G-type stars and a power-law distribution indicated by the exoplanets detected by the radial velocity technique. We find that the GPI could detect exoplanets of all the F and G spectral type stars in the BPMG sample with a probability that depends on the brightness model and semi-major axis distribution. At spectral type K-M1, exoplanet detectability depends on brightness and hence distance of the host star. GPI will be able to detect the companions of M stars later than M1 only if they are closer than 10 pc. Of the four A stars in the BPMG sample, only one has a V-band brightness in the range of GPI; the others are too bright.

  6. More on the circumbinary disk of SS 433

    NASA Astrophysics Data System (ADS)

    Bowler, M. G.

    2011-07-01

    Context. Certain lines in spectra of the Galactic microquasar SS 433, in particular the brilliant Balmer Hα line, have been interpreted as emission from a circumbinary disk. In this interpretation the orbital speed of the glowing material is in excess of 200 km s-1 and the mass of the binary system in excess of 40 M⊙. A very simple model for excitation of disk material is in remarkable agreement with the observations, yet it seems that the very existence of a circumbinary disk is regarded as controversial. Aims: We investigate whether analysis of optical data from Hα and He I spectral lines in terms of a model, in which the disk is excited by radiation from the close environment of the compact object, can further illuminate the origin of these split spectral lines. Methods: A model in which the excitation of any given patch of putative circumbinary disk material is proportional to the inverse square of its instantaneous distance from the compact object was constructed and compared with published spectra, taken almost nightly over two orbital periods of the binary system. The Hα and He I lines were analysed as superpositions of Gaussian components. Results: The new model provides an excellent description of the observations. The variations of the Hα and He I spectra with orbital phase are described quantitatively, provided the radius of the orbit of the emitting ring is not much greater than the radius of the closest stable circumbinary orbit. The observed variations with orbital phase are not consistent with an origin in a radially expanding ring. Conclusions: The new analysis has greatly strengthened the case for a circumbinary disk orbiting the SS 433 system with a speed of over 200 km s-1 and presents supposed alternative explanations with major difficulties. If the circumbinary disk scenario is essentially correct, the mass of the binary system must exceed 40 M⊙ and the compact object must be a rather massive stellar black hole. This possibility should

  7. Interpretation of observations of the circumbinary disk of SS 433

    NASA Astrophysics Data System (ADS)

    Bowler, M. G.

    2010-10-01

    Context. The Galactic microquasar SS 433 possesses a circumbinary disk most clearly seen in the brilliant Balmer Hα emission line. The orbital speed of the glowing material is an important determinant of the mass of the binary system. The circumbinary disk may be fed through the L2 point and in turn may feed a very extended radio feature known as the ruff. Aims: We present (i) an analysis of spectroscopic optical data from Hα and He I spectral lines which reveal the circumbinary disk (ii) comparisons of the rather different signals, to better understand the disk and improve estimates of the rotational speed of the inner rim (iii) a simple model that naturally explains some apparently bizarre spectral variations with orbital phase. Methods: Published spectra, taken almost nightly over two orbital periods of the binary system, show Hα and He I lines. These were analysed as superpositions of Gaussian components and a simple model in terms of a circumbinary disk was constructed. The possible contributions to the signal of an outflow through the L2 point were considered. Results: The data can be understood in terms of a hot spot, generated in proximity to the compact object and rotating round the inner circumbinary disk with a period of 13 days. The glowing material fades with time, quite slowly for the Hα source but more rapidly for the He I spectral lines. The orbital speed of the inner rim is approximately 250 km s-1. It may be that absorption lines attributed to the atmosphere of the companion are in fact formed in this circumbinary material. Conclusions: The mass of the binary system must exceed 40 M_⊙ and the compact object must be a rather massive stellar black hole. The corollary is that the orbital speed of the companion must exceed 130 km s-1.

  8. Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, Shawn D.; Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

    2011-06-01

    We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases - and therefore the life that produces them - ;if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.

  9. Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets.

    PubMed

    Domagal-Goldman, Shawn D; Meadows, Victoria S; Claire, Mark W; Kasting, James F

    2011-06-01

    We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. PMID:21663401

  10. Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets

    PubMed Central

    Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

    2011-01-01

    Abstract We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases—and therefore the life that produces them—if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. Key Words: Exoplanets—Biosignatures—Anoxic atmospheres—Planetary atmospheres—Remote life detection—Photochemistry. Astrobiology 11, 419–441. PMID:21663401