Science.gov

Sample records for low-mass extrasolar planets

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. The HARPS search for southern extra-solar planets. XXVIII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems

    NASA Astrophysics Data System (ADS)

    Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bertaux, J.-L.; Bouchy, F.; Correia, A. C. M.; Laskar, J.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.

    2011-04-01

    Context. Low-mass extrasolar planets are presently being discovered at an increased pace by radial velocity and transit surveys, which opens a new window on planetary systems. Aims: We are conducting a high-precision radial velocity survey with the HARPS spectrograph, which aims at characterizing the population of ice giants and super-Earths around nearby solar-type stars. This will lead to a better understanding of their formation and evolution, and will yield a global picture of planetary systems from gas giants down to telluric planets. Methods: Progress has been possible in this field thanks in particular to the sub-m s-1 radial velocity precision achieved by HARPS. We present here new high-quality measurements from this instrument. Results: We report the discovery of a planetary system comprising at least five Neptune-like planets with minimum masses ranging from 12 to 25 M⊕, orbiting the solar-type star HD 10180 at separations between 0.06 and 1.4 AU. A sixth radial velocity signal is present at a longer period, probably caused by a 65-M⊕ object. Moreover, another body with a minimum mass as low as 1.4 M⊕ may be present at 0.02 AU from the star. This is the most populated exoplanetary system known to date. The planets are in a dense but still well separated configuration, with significant secular interactions. Some of the orbital period ratios are fairly close to integer or half-integer values, but the system does not exhibit any mean-motion resonances. General relativity effects and tidal dissipation play an important role to stabilize the innermost planet and the system as a whole. Numerical integrations show long-term dynamical stability provided true masses are within a factor ~3 from minimum masses. We further note that several low-mass planetary systems exhibit a rather "packed" orbital architecture with little or no space left for additional planets. In several cases, semi-major axes are fairly regularly spaced on a logarithmic scale, giving rise

  6. Characterizing extrasolar planets

    NASA Astrophysics Data System (ADS)

    Brown, Timothy M.

    Transiting extrasolar planets provide the best current opportunities for characterizing the physical properties of extrasolar planets. In this review, I first describe the geometry of planetary transits, and methods for detecting and refining the observations of such transits. I derive the methods by which transit light curves and radial velocity data can be analyzed to yield estimates of the planetary radius, mass, and orbital parameters. I also show how visible-light and infrared spectroscopy can be valuable tools for understanding the composition, temperature, and dynamics of the atmospheres of transiting planets. Finally, I relate the outcome of a participatory lecture-hall exercise relating to one term in the Drake equation, namely the lifetime of technical civilizations.

  7. Commission 53: Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Boss, Alan; Lecavelier des Etangs, Alain; Mayor, Michel; Bodenheimer, Peter; Collier-Cameron, Andrew; Kokubo, Eiichiro; Mardling, Rosemary; Minniti, Dante; Queloz, Didier

    2012-04-01

    Commission 53 was created at the 2006 Prague General Assembly (GA) of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets (WGESP), which ended its six years of existence in August 2006. The founding President of Commission 53 was Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The current President is Alan Boss, the former chair of the WGESP. The current members of the Commission 53 (C53) Organizing Committee (OC) began their service in August 2009 at the conclusion of the Rio de Janeiro IAU GA.

  8. The Atmospheres of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Richardson, L. J.; Seager, S.

    2007-01-01

    In this chapter we examine what can be learned about extrasolar planet atmospheres by concentrating on a class of planets that transit their parent stars. As discussed in the previous chapter, one way of detecting an extrasolar planet is by observing the drop in stellar intensity as the planet passes in front of the star. A transit represents a special case in which the geometry of the planetary system is such that the planet s orbit is nearly edge-on as seen from Earth. As we will explore, the transiting planets provide opportunities for detailed follow-up observations that allow physical characterization of extrasolar planets, probing their bulk compositions and atmospheres.

  9. Extrasolar Planets in the Classroom

    ERIC Educational Resources Information Center

    George, Samuel J.

    2011-01-01

    The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique.…

  10. Mass-Radius Relationships for Low-Mass Planets: From Iron Planets to Water Planets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2007-01-01

    Transit observations, and radial velocity measurements, have begun to populate the mass radius diagram for extrasolar planets; fubture astrometric measurements and direct images promise more mass and radius information. Clearly, the bulk density of a planet indicates something about a planet s composition--but what? I will attempt to answer this question in general for low-mass planets (low-mass planets obey a kind of universal mass-radius relationship: an expansion whose first term is M approx. R(sup 3).

  11. Transit of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.

    1998-01-01

    During the past five years we have pursued the detection of extrasolar planets by the photometric transit method, i.e. the detection of a planet by watching for a drop in the brightness of the light as it crosses in front of a star. The planetary orbit must cross the line-of-sight and so most systems will not be lined up for such a transit to ever occur. However, we have looked at eclipsing binary systems which are already edge-on. Such systems must be very small in size as this makes the differential light change due to a transit much greater for a given planet size (the brightness difference will be proportional to the area of the transiting planet to the disc area of the star). Also, the planet forming region should be closer to the star as small stars are generally less luminous (that is, if the same thermal regime for planet formation applies as in the solar system). This led to studies of the habitable zone around other stars, as well. Finally, we discovered that our data could be used to detect giant planets without transits as we had been carefully timing the eclipses of the stars (using a GPS antenna for time) and this will drift by being offset by any giant planets orbiting around the system, as well. The best summary of our work may be to just summarize the 21 refereed papers produced during the time of this grant. This will be done is chronological order and in each section separately.

  12. Taxonomy of the extrasolar planet.

    PubMed

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1. PMID:22506608

  13. 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.

  14. Atmospheres of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark

    2006-01-01

    The next decade will almost certainly see the direct imaging of extrasolar giant planets around nearby stars. Unlike purely radial velocity detections, direct imaging will open the door to characterizing the atmosphere and interiors of extrasola planets and ultimately provide clues on their formation and evolution through time. This process has already begun for the transiting planets, placing new constraints on their atmospheric structure, composition, and evolution. Indeed the key to understanding giant planet detectability, interpreting spectra, and constraining effective temperature and hence evolution-is the atmosphere. I will review the universe of extrasolar giant planet models, focusing on what we have already learned from modeling and what we will likely be able to learn from the first generation of direct detection data. In addition to these theoretical considerations, I will review the observations and interpretation of the - transiting hot Jupiters. These objects provide a test of our ability to model exotic atmospheres and challenge our current understanding of giant planet evolution.

  15. Chemical kinetics on extrasolar planets.

    PubMed

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately <2000K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets. PMID:24664912

  16. Observed properties of extrasolar planets.

    PubMed

    Howard, Andrew W

    2013-05-01

    Observational surveys for extrasolar planets probe the diverse outcomes of planet formation and evolution. These surveys measure the frequency of planets with different masses, sizes, orbital characteristics, and host star properties. Small planets between the sizes of Earth and Neptune substantially outnumber Jupiter-sized planets. The survey measurements support the core accretion model, in which planets form by the accumulation of solids and then gas in protoplanetary disks. The diversity of exoplanetary characteristics demonstrates that most of the gross features of the solar system are one outcome in a continuum of possibilities. The most common class of planetary system detectable today consists of one or more planets approximately one to three times Earth's size orbiting within a fraction of the Earth-Sun distance. PMID:23641110

  17. 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

  18. Testing the correlation between low mass planets and debris disks

    NASA Astrophysics Data System (ADS)

    Kalas, Paul

    2014-10-01

    The number of dusty debris disks has increased across all spectral types through recent infrared surveys. This has provided greater overlap with stars known to host extrasolar planets via RV surveys. New studies have therefore investigated how the different properties of host stars, exoplanets, and debris disks may be correlated, with the objective of giving empirical support to competing theories of planet formation and evolution. One such emerging correlation is that stars with only low mass planets are more likely to host prominent debris disks than stars that have at least one giant planet. If true, then M dwarfs should have abundant debris disks given that they more frequently have low mass planetary systems. However, the information needed to critically test these ideas is lacking. For most systems, the presence of an outer planet with >30 Earth masses has not been observationally tested, nor are there many M dwarf debris disks available for detailed scrutiny. Here we propose to use STIS coronagraphy to image for the first time the debris disks around three nearby stars in optical scattered light. Searching for sharp dust belt structures indirectly tests for the existence of outer planets that are otherwise undetectable by RV or adaptive optics planet searches. Moreover, two of our target stars are the most recently discovered M dwarf debris disks, both closer to the Sun than AU Mic. The scattered light observations of these two targets would present a major advance in characterizing how M dwarf debris disks co-evolve with planets under different stellar environments.

  19. The Realm of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ferlet, Roger

    2010-10-01

    In November 1995, an article published in Nature [1] put planetary sciences not only as a new hot field in both observational and theoretical astrophysics but also as a topic with a large impact toward the layman. This article was reporting the first discovery of a planet orbiting a star beyond our Sun, namely the solar-type star 51 Pegasi. Nearly four centuries after Giordano Bruno was burnt in public in Roma partly for having intuitively claimed the plurality of worlds, we were entering the extraordinary epoch in which one of the oldest inquiries of mankind-are we alone in the Universe?-can be tackled with the scientific method, leaving aside centuries of endless speculations. To date (July 2010), almost 500 extrasolar planets are known. We shall briefly review the main detection methods, together with the big surprises which arose during these last exciting fifteen years, without being exhaustive.

  20. Electrodynamics on extrasolar giant planets

    SciTech Connect

    Koskinen, T. T.; Yelle, R. V.; Lavvas, P.; Cho, J. Y-K.

    2014-11-20

    Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter the energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially be

  1. 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.

  2. 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.

  3. A Decade of Extrasolar Planets around Normal Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Sahu, Kailash; Valenti, Jeff

    2008-06-01

    1. Extrasolar planets: past, present, and future A. P. Boss; 2. The quest for very low-mass planets M. Mayor, F. Pepe, C. Lovis, D. Queloz and S. Udry; 3. Extrasolar planets: a galactic perspective I. N. Reid; 4. The Kepler Mission: Design, expected science results, opportunities to participate W. J. Borucki, D. Koch, G. Basri, T. Brown, D. Caldwell, E. Devore, E. Dunham, T. Gautier, J. Geary, R. Gilliland, A. Gould, S. Howell, J. Jenkins and D. Latham; 5. Observations of the atmospheres of extrasolar planets T. M. Brown, R. Alonso, M. Knölker, H. Rauer and W. Schmidt; 6. Planetary migration P. J. Armitage and W. K. M. Rice; 7. Observational constraints on dust disk lifetimes: implications for planet formation L. A. Hillenbrand; 8. The evolution of gas in disks J. Najita; 9. Planet formation J.J. Lissauer; 10. Core accretion-gas capture model for gas giant planet formation O. Hubickyj; 11. Gravitational instabilities in protoplanetary disks R. H. Durisen; 12. Conference summary: the quest for new worlds J. E. Pringle.

  4. A Decade of Extrasolar Planets around Normal Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Sahu, Kailash; Valenti, Jeff

    2011-04-01

    1. Extrasolar planets: past, present, and future A. P. Boss; 2. The quest for very low-mass planets M. Mayor, F. Pepe, C. Lovis, D. Queloz and S. Udry; 3. Extrasolar planets: a galactic perspective I. N. Reid; 4. The Kepler Mission: Design, expected science results, opportunities to participate W. J. Borucki, D. Koch, G. Basri, T. Brown, D. Caldwell, E. Devore, E. Dunham, T. Gautier, J. Geary, R. Gilliland, A. Gould, S. Howell, J. Jenkins and D. Latham; 5. Observations of the atmospheres of extrasolar planets T. M. Brown, R. Alonso, M. Knölker, H. Rauer and W. Schmidt; 6. Planetary migration P. J. Armitage and W. K. M. Rice; 7. Observational constraints on dust disk lifetimes: implications for planet formation L. A. Hillenbrand; 8. The evolution of gas in disks J. Najita; 9. Planet formation J.J. Lissauer; 10. Core accretion-gas capture model for gas giant planet formation O. Hubickyj; 11. Gravitational instabilities in protoplanetary disks R. H. Durisen; 12. Conference summary: the quest for new worlds J. E. Pringle.

  5. PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

    SciTech Connect

    Brown, Robert A.

    2009-09-10

    We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in

  6. Characterization of Extrasolar Planets Using SOFIA

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    2010-01-01

    Topics include: the landscape of extrasolar planets, why focus on transiting planets, some history and Spitzer results, problems in atmospheric structure or hot Jupiters and hot super Earths, what observations are needed to make progress, and what SOFIA can currently do and comments on optimized instruments.

  7. Observational Studies of Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Southworth, J.

    2015-07-01

    The study of transiting extrasolar planets is only 15 years old, but has matured into a rich area of research. I review the observational aspects of this work, concentrating on the discovery of transits, the characterization of planets from photometry and spectroscopy, the Homogeneous Studies project, starspots, orbital obliquities, and the atmospheric properties of the known planets. I begin with historical context and conclude with a glance to a future of TESS, CHEOPS, Gaia and PLATO.

  8. Infrared and the search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Meinel, Aden B.; Meinel, Marjorie P.

    1991-01-01

    Search for evidence concerning the existence of extrasolar planets will involve both indirect detection as well as direct (imaging). Indirect detection may be possible using ground based instrumentation on the Keck telescope, Imaging probably will require an orbiting system. Characterizing other planets for complex molecules will require a large orbiting or lunar-based telescope or inteferometer. Cryogenic infrared techniques appear to be necessary. Planning for a NASA ground and space-based program, Toward Other Planet Systems (TOPS), is proceeding.

  9. Spectra and Biomarkers of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Traub, Wesley A.

    2005-01-01

    During this period, and focussing on ow work at SAO only, we have produced significant results in five areas: coronagraphs, color, Earthshine, near infrared, and meetings. We developed the theory of a new type of coronograph for detecting and characterizing extrasolar planets. We wrote two papers, the first laying out the one-dimensional theory, and the second developing the two-dimensional theory, plus additional results. We gained new insights into the role that simple color measurements can play in characterizing extrasolar planets.

  10. [Extrasolar terrestrial planets and possibility of extraterrestrial life].

    PubMed

    Ida, Shigeru

    2003-12-01

    Recent development of research on extrasolar planets are reviewed. About 120 extrasolar Jupiter-mass planets have been discovered through the observation of Doppler shift in the light of their host stars that is caused by acceleration due to planet orbital motions. Although the extrasolar planets so far observed may be limited to gas giant planets and their orbits differ from those of giant planets in our Solar system (Jupiter and Saturn), the theoretically predicted probability of existence of extrasolar terrestrial planets that can have liquid water ocean on their surface is comparable to that of detectable gas giant planets. Based on the number of extrasolar gas giants detected so far, about 100 life-sustainable planets may exist within a range of 200 light years. Indirect observation of extrasolar terrestrial planets would be done with space telescopes within several years and direct one may be done within 20 years. The latter can detect biomarkers on these planets as well. PMID:15136756

  11. A spectrum of an extrasolar planet.

    PubMed

    Richardson, L Jeremy; Deming, Drake; Horning, Karen; Seager, Sara; Harrington, Joseph

    2007-02-22

    Of the over 200 known extrasolar planets, 14 exhibit transits in front of their parent stars as seen from Earth. Spectroscopic observations of the transiting planets can probe the physical conditions of their atmospheres. One such technique can be used to derive the planetary spectrum by subtracting the stellar spectrum measured during eclipse (planet hidden behind star) from the combined-light spectrum measured outside eclipse (star + planet). Although several attempts have been made from Earth-based observatories, no spectrum has yet been measured for any of the established extrasolar planets. Here we report a measurement of the infrared spectrum (7.5-13.2 microm) of the transiting extrasolar planet HD 209458b. Our observations reveal a hot thermal continuum for the planetary spectrum, with an approximately constant ratio to the stellar flux over this wavelength range. Superposed on this continuum is a broad emission peak centred near 9.65 microm that we attribute to emission by silicate clouds. We also find a narrow, unidentified emission feature at 7.78 microm. Models of these 'hot Jupiter' planets predict a flux peak near 10 microm, where thermal emission from the deep atmosphere emerges relatively unimpeded by water absorption, but models dominated by water fit the observed spectrum poorly. PMID:17314975

  12. FAME's Search for Extrasolar Planet Candidates

    NASA Astrophysics Data System (ADS)

    Johnston, K.

    FAME is a five year survey mission to observe the positions, proper motions, and parallaxes of 40,000,000 stars down to 15th magnitude with accuracies of 50 microarcseconds at 9th magnitude. In addition to producing an astrometric and photometric catalog unparalleled for its accuracy and size, the survey will provide significant astrophysics results and search for extrasolar planet candidates.

  13. Dynamical Interactions Among Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Laughlin, G.

    For certain multiple planet systems such as GJ 876 and 55 Cancri, which have (1) been observed for a large number of orbital periods, and which (2) have strong planet-planet gravitational interactions, the approximation that the planets are orbiting on independent Keplerian ellipses is inadequate. We discuss the production of self-consistent dynamical fits to these interacting systems, in which a minimization scheme (such as the Levenberg-Marquardt technique, or a Genetic Algorithm) is used to repeatedly drive an N-body integrator and improve the agreement between the integrated reflex motion of the central star and the observed radial velocities.

  14. Planet Formation and the Characteristics of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    An overview of current theories of planetary growth, emphasizing the formation of extrasolar planets, is presented. Models of planet formation are based upon observations of the Solar System, extrasolar planets, and young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  15. Direct imaging of extra-solar planets

    SciTech Connect

    Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

    1997-03-01

    Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

  16. PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS. II. PREDICTIONS FOR OUTER EXTRASOLAR PLANETARY SYSTEMS

    SciTech Connect

    Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

    2010-03-10

    We develop an idealized dynamical model to predict the typical properties of outer extrasolar planetary systems, at radii comparable to the Jupiter-to-Neptune region of the solar system. The model is based upon the hypothesis that dynamical evolution in outer planetary systems is controlled by a combination of planet-planet scattering and planetary interactions with an exterior disk of small bodies ('planetesimals'). Our results are based on 5000 long duration N-body simulations that follow the evolution of three planets from a few to 10 AU, together with a planetesimal disk containing 50 M{sub +} from 10 to 20 AU. For large planet masses (M {approx}> M{sub Sat}), the model recovers the observed eccentricity distribution of extrasolar planets. For lower-mass planets, the range of outcomes in models with disks is far greater than that which is seen in isolated planet-planet scattering. Common outcomes include strong scattering among massive planets, sudden jumps in eccentricity due to resonance crossings driven by divergent migration, and re-circularization of scattered low-mass planets in the outer disk. We present the distributions of the eccentricity and inclination that result, and discuss how they vary with planet mass and initial system architecture. In agreement with other studies, we find that the currently observed eccentricity distribution (derived primarily from planets at a {approx}< 3 AU) is consistent with isolated planet-planet scattering. We explain the observed mass dependence-which is in the opposite sense from that predicted by the simplest scattering models-as a consequence of strong correlations between planet masses in the same system. At somewhat larger radii, initial planetary mass correlations and disk effects can yield similar modest changes to the eccentricity distribution. Nonetheless, strong damping of eccentricity for low-mass planets at large radii appears to be a secure signature of the dynamical influence of disks. Radial velocity

  17. Thermal escape from extrasolar giant planets.

    PubMed

    Koskinen, Tommi T; Lavvas, Panayotis; Harris, Matthew J; Yelle, Roger V

    2014-04-28

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres. PMID:24664923

  18. Optical Spectra of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Hubeny, Ivan; Sudarsky, David; Burrows, Adam

    2004-01-01

    The flux distribution of a planet relative to its host star is a critical quantity for planning space observatories to detect and characterize extrasolar giant planets (EGP's). In this paper, we present optical planet-star contrasts of Jupiter-mass planets as a function of stellar type, orbital distance, and planetary cloud characteristics. As originally shown by Sudarsky et al. (2000, 2003), the phaseaveraged brightness of an EGP does not necessarily decrease monotonically with greater orbital distance because of changes in its albedo and absorption spectrum at lower temperatures. We apply our results to Eclipse, a 1.8-m optical telescope + coronograph to be proposed as a NASA Discovery mission later this year.

  19. Thermal escape from extrasolar giant planets

    PubMed Central

    Koskinen, Tommi T.; Lavvas, Panayotis; Harris, Matthew J.; Yelle, Roger V.

    2014-01-01

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres. PMID:24664923

  20. The Evryscope and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Fors, Octavi; Law, Nicholas Michael; Ratzloff, Jeffrey; del Ser, Daniel; Wulfken, Philip J.; Kavanaugh, Dustin

    2015-08-01

    The Evryscope (Law et al. 2015) is a 24-camera hemispherical all-sky gigapixel telescope (8,000 sq.deg. FoV) with rapid cadence (2mins exposure, 4sec readout) installed at CTIO. Ground-based single-station transiting surveys typically suffer from light curve sparsity and suboptimal efficiency because of their limited field of view (FoV), resulting in incomplete and biased detections. In contrast, the Evryscope offers 97% survey efficiency and one of the single-station most continuous and simultaneous monitoring of millions of stars (only limited by the day-night window).This unique facility is capable of addressing new and more extensive planetary populations, including: 1) for the first time, continuously monitor every 2mins a set of ~1000 bright white dwarfs (WDs). This will allow us to put constraints on the habitable planet fraction of Ceres-size planetesimals at the level of 30%, only in a survey timescales of a few weeks, as well as first-time testing planetary evolution models beyond the AGB phase. 2) search for rocky planets in the habitable zone around ~5,000 bright, nearby M-dwarfs. 3) synergies between Evryscope and upcoming exoplanets missions (e.g. TESS, PLATO) are also promising for target pre-imaging characterization, and increasing the giant planet yield by recovering multiple transits from planets seen as single transit events from space. 4) all-sky 2-min cadence of rare microlensing events of nearby stars. 5) all-sky continuous survey of microlensing events of nearby stars at 2mins cadence. 6) increase the census of giant planets around ~70,000 nearby, bright (g<10) solar-type stars, whose atmospheres can be characterized by follow-up observations. We are developing new data analysis algorithms to address the above scientific goals: from detecting the extremely short and faint transits around WDs, to disentangle planetary signals from very bright stars, and to combine space-based light curves with the Evryscope's ones. We will present the first

  1. Infrared imaging of extrasolar planets

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Tubbs, Eldred F.; Gaiser, Steven L.; Korechoff, Robert P.

    1991-01-01

    An optical system for direct detection, in the infrared, of planets orbiting other stars is described. The proposed system consists of a large aperture (about 16 m) space-based telescope to which is attached a specialized imaging instrument containing a set of optical signal processing elements to suppress diffracted light from the central star. Starlight suppression is accomplished using coronagraphic apodization combined with rotational shearing interferometry. The possibility of designing the large telescope aperture to be of a deployable, multiarm configuration is examined, and it is shown that there is some sacrifice in performance relative to a filled, circular aperture.

  2. IONIZATION OF EXTRASOLAR GIANT PLANET ATMOSPHERES

    SciTech Connect

    Koskinen, Tommi T.; Cho, James Y-K.; Achilleos, Nicholas; Aylward, Alan D.

    2010-10-10

    Many extrasolar planets orbit close in and are subject to intense ionizing radiation from their host stars. Therefore, we expect them to have strong, and extended, ionospheres. Ionospheres are important because they modulate escape in the upper atmosphere and can modify circulation, as well as leave their signatures, in the lower atmosphere. In this paper, we evaluate the vertical location Z{sub I} and extent D{sub I} of the EUV ionization peak layer. We find that Z{sub I{approx}}1-10 nbar-for a wide range of orbital distances (a = 0.047-1 AU) from the host star-and D{sub I}/H{sub p{approx}}>15, where H{sub p} is the pressure scale height. At Z{sub I}, the plasma frequency is {approx}80-450 MHz, depending on a. We also study global ion transport, and its dependence on a, using a three-dimensional thermosphere-ionosphere model. On tidally synchronized planets with weak intrinsic magnetic fields, our model shows only a small, but discernible, difference in electron density from the dayside to the nightside ({approx}9 x 10{sup 13} m{sup -3} to {approx}2 x 10{sup 12} m{sup -3}, respectively) at Z{sub I}. On asynchronous planets, the distribution is essentially uniform. These results have consequences for hydrodynamic modeling of the atmospheres of close-in extrasolar giant planets.

  3. 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

  4. Direct Imaging of Warm Extrasolar Planets

    SciTech Connect

    Macintosh, B

    2005-04-11

    One of the most exciting scientific discoveries in the last decade of the twentieth century was the first detection of planets orbiting a star other than our own. By now more than 130 extrasolar planets have been discovered indirectly, by observing the gravitational effects of the planet on the radial velocity of its parent star. This technique has fundamental limitations: it is most sensitive to planets close to their star, and it determines only a planet's orbital period and a lower limit on the planet's mass. As a result, all the planetary systems found so far are very different from our own--they have giant Jupiter-sized planets orbiting close to their star, where the terrestrial planets are found in our solar system. Such systems have overturned the conventional paradigm of planet formation, but have no room in them for habitable Earth-like planets. A powerful complement to radial velocity detections of extrasolar planets will be direct imaging--seeing photons from the planet itself. Such a detection would allow photometric measurements to determine the temperature and radius of a planet. Also, direct detection is most sensitive to planets in wide orbits, and hence more capable of seeing solar systems resembling our own, since a giant planet in a wide orbit does not preclude the presence of an Earth-like planet closer to the star. Direct detection, however, is extremely challenging. Jupiter is roughly a billion times fainter than our sun. Two techniques allowed us to overcome this formidable contrast and attempt to see giant planets directly. The first is adaptive optics (AO) which allows giant earth-based telescopes, such as the 10 meter W.M. Keck telescope, to partially overcome the blurring effects of atmospheric turbulence. The second is looking for young planets: by searching in the infrared for companions to young stars, we can see thermal emission from planets that are still warm with the heat of their formation. Together with a UCLA team that leads the

  5. 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

  6. Orbital Evolution and Migration of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Trilling, D. E.; Benz, W.; Guillot, T.; Lunine, J. I.; Hubbard, W. B.; Burrows, A.

    1997-07-01

    Giant planets in circumstellar disks can migrate inward from their initial (formation) positions. Migration is caused by inward torques between the planet and the disk; by outward torques between the planet and the spinning star; and by outward torques due to Roche lobe overflow and mass loss from the planet. Summing torques on planets in disks with various physical parameters, we find that Jupiter-mass planets can stably arrive and survive at small heliocentric distances. Inward migration timescales can be approximately equal to or less than disk lifetimes and star spindown timescales. Therefore, the range of fates of Jupiter-mass planets is broad, and generally comprises three classes: (I) planets which migrate inward too rapidly and lose all their mass due to Roche lobe overflow; (II) planets which migrate inward and survive in very small orbits; and (III) planets which do not migrate very far. Some, but not all, of the planets in Class II lose mass during their evolution and migration times, resulting in planets with final masses smaller than their initial masses. For example, in our model, we produce planets similar to 51 Peg b which have lost ~ 75% of their initial mass. The observed extrasolar planets, both those with extremely small semi-major axes (51 Peg b at 0.05 AU, tau Boo b (0.046 AU), upsilon And b (0.057 AU), and 55 Cnc b (0.11 AU)) and those with more moderate semi-major axes (rho Cor Bor b (0.23 AU), 47 UMa b (2.1 AU)) form a subset of the potential outcomes of the system, in that Jupiter-mass objects can stably survive in orbits with a wide range of semi-major axes. Our numerical model produces planets which have similar characteristics to the observed planets, as well as planets similar to Jupiter, and many intermediate cases. Since Jupiters can stably migrate to various orbital separations, we predict that, as planetary detection techniques improve, Jupiter-mass planets will be found in a wide range of orbits, from much less than 1 AU to

  7. Chemical Characterization of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Madhusudhan, Nikku

    2016-07-01

    Exoplanetary discoveries in the past two decades have unveiled an astonishing diversity in the physical characteristics of exoplanetary systems, including their orbital properties, masses, radii, equilibrium temperatures, and stellar hosts. Exoplanets known today range from gas-giants to nearly Earth-size planets, and some even in the habitable zones of their host stars. Recent advances in exoplanet observations and theoretical methods are now leading to unprecedented constraints on the physicochemical properties of exoplanetary atmospheres, interiors, and their formation conditions. I will discuss the latest developments and future prospects of this new era of exoplanetary characterization. In particular, I will present some of the latest constraints on atmospheric chemical compositions of exoplanets, made possible by state-of-the-art high-precision observations from space and ground, and their implications for atmospheric processes and formation conditions of exoplanets. The emerging framework for using atmospheric elemental abundance ratios for constraining the origins and migration pathways of giant exoplanets, e.g. hot Jupiters, will also be discussed. A survey of theoretical and observational directions in the field will be presented along with several open questions on the horizon.

  8. An extrasolar planetary system with three Neptune-mass planets.

    PubMed

    Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Alibert, Yann; Benz, Willy; Bouchy, François; Correia, Alexandre C M; Laskar, Jacques; Mordasini, Christoph; Queloz, Didier; Santos, Nuno C; Udry, Stéphane; Bertaux, Jean-Loup; Sivan, Jean-Pierre

    2006-05-18

    Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star. PMID:16710412

  9. 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.

  10. 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.

  11. Division F Commission 53: Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Lecavelier Des Etangs, Alain; Minniti, Dante; Boss, Alan; Mayor, Michel; Bodenheimer, Peter; Collier-Cameron, Andrew; Jayawardhana, Ray; Kokubo, Eiichiro; Mardling, Rosemary; Queloz, Didier; Rauer, Heike; Zhao, Gang

    2016-04-01

    The IAU Working Group on Extrasolar Planets (WGESP) was created by the Executive Council as a Working Group of Division III. This decision took place in June 1999, that is only 7 years after the discovery of planets around the pulsar PSR B1257+12 and 4 years after the discovery of 51 Peg b. This working group was renewed for 3 years at the General Assembly in 2003 in Sydney, Australia. It was chaired by Alan Boss from Carnegie Institution of Washington. The WGESP members were Paul Butler, William Hubbard, Philip Ianna, Martin Kürster, Jack Lissauer, Michel Mayor, Karen Meech, Francois Mignard, Alan Penny, Andreas Quirrenbach, Jill Tarter, and Alfred Vidal-Madjar.

  12. Automatic Telescope Search for Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Henry, Gregory W.

    1998-01-01

    We are using automatic photoelectric telescopes at the Tennessee State University Center for Automated Space Science to search for planets around nearby stars in our galaxy. Over the past several years, wc have developed the capability to make extremely precise measurements of brightness changes in Sun-like stars with automatic telescopes. Extensive quality control and calibration measurements result in a precision of 0.l% for a single nightly observation and 0.0270 for yearly means, far better than previously thought possible with ground-based observations. We are able, for the first time, to trace brightness changes in Sun-like stars that are of similar amplitude to brightness changes in the Sun, whose changes can be observed only with space-based radiometers. Recently exciting discoveries of the first extrasolar planets have been announced, based on the detection of very small radial-velocity variations that imply the existence of planets in orbit around several Sun-like stars. Our precise brightness measurements have been crucial for the confirmation of these discoveries by helping to eliminate alternative explanations for the radial-velocity variations. With our automatic telescopes, we are also searching for transits of these planets across the disks of their stars in order to conclusively verify their existence. The detection of transits would provide the first direct measurements of the sizes, masses, and densities of these planets and, hence, information on their compositions and origins.

  13. 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.

  14. Atmospheric circulation of eccentric extrasolar giant planets

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole Kae

    This dissertation explores the three-dimensional coupling between radiative and dynamical processes in the atmospheres of eccentric extrasolar giant planets GJ436b, HAT-P-2b, and HD80606b. Extrasolar planets on eccentric orbits are subject to time-variable heating and probable non-synchronous rotation, which results in significant variations in global circulation and thermal patterns as a function of orbital phase. Atmospheric simulations for the low eccentricity (e=0.15) Neptune sized planet GJ436b reveal that when Neptune-like atmospheric compositions are assumed day/night temperature contrasts and equatorial jet speeds are significantly increased relative to models that assume a solar-like composition. Comparisons between our theoretical light curves and recent observations support a high metallicity atmosphere with disequilibrium carbon chemistry for GJ436b. The analysis of full-orbit light curve observations at 3.6 and 4.5 microns of the HAT-P-2 system reveal swings in the planet's temperature of more than 900 K during its significantly eccentric ( e=0.5) orbit with a four to six hour offset between periapse passage and the peak of the planet's observed flux. Comparisons between our atmospheric model of HAT-P-2b and the observed light curves indicate an increased carbon to oxygen ratio in HAT-P-2b's atmosphere compared to solar values. Atmospheric simulations of the highly eccentric (e=0.9) HD80606b show that flash-heating events completely alter planetary thermal and jet structures and that assumptions about the rotation period of this planet could affect the shape of light curve observations near periapse. Our simulations of HD80606b also show the development an atmospheric shock on the nightside of the planet that is associated with an observable thermal signature in our theoretical light curves. The simulations and observations presented in this dissertation mark an important step in the exploration of atmospheric circulation on the more than 300

  15. Understanding the Atmospheres of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Marley, Mark S.; Fortney, J.

    2007-10-01

    With the direct measurement of thermal emission (and perhaps soon reflected light) from the 'hot Jupiters', extrasolar planetary science is transitioning from discovery to characterization. Familiar attributes of solar system giant planet atmospheres, including hot stratospheres, clouds, redistribution of heat by winds, and perhaps even non-equilibrium molecular abundances and photochemical products have been recognized and modeled in some of these exotic atmospheres. Despite the fact that atmospheric dynamics undoubtedly plays a major role in controlling the thermal structures of these planets, one-dimensional radiative-convective equilibrium models are still exceptionally useful for understanding the baseline atmospheric physics and resultant thermal structure. Our group's apparently successful prediction of a hot stratosphere on planet HD 149026b is emblematic of the utility of 1D models. In the talk we will review our efforts to model the vertical structure of several of the hot Jupiters, focusing on the processes that play major roles in influencing the atmospheric chemical and temperature profiles. We will highlight processes (e.g., photochemistry acting on S-, P-, N-, and O- as well as C-bearing molecules) that are ripe for further modeling. Given that measurements of thermal emission in various Spitzer mid-infrared bands will soon be published for 10 planets, unprecedented opportunities for comparative exoplanetary science are now at hand.

  16. Chandra Pilot Survey of Extrasolar Planet Candidates

    NASA Astrophysics Data System (ADS)

    Tsuboi, Yohko

    2012-09-01

    We propose to detect planetary-mass companion around young nearby stars by X-ray direct imaging observations with Chandra. Our goals are to determine I. if the X-ray band can be a new probe to the exo-planet search, and II. if a planet emit detectable X-rays with a magnetic origin at a young age. This should be a challenging observation but a brand-new discovery space unique to Chandra. The abundant population of YSOs in the same field of view will enable us to obtain complete X-ray catalogues of YSOs with all categories of masses. We will also execute simultaneous deep NIR observations with IRSF/SIRIUS and Nishiharima 2m telescope to search for the other X-ray-emitting very low-mass objects near our aiming planet candidates.

  17. Extrasolar Planet Inferometric Survey (EPIcS)

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Baliunas, Sallie; Boden, Andrew; Kulkarni, Shrinivas; Lin, Douglas N. C.; Loredo, Tom; Queloz, Didier; Shaklan, Stuart; Tremaine, Scott; Wolszczan, Alexander

    2004-01-01

    The discovery of the nature of the solar system was a crowning achievement of Renaissance science. The quest to evaluate the properties of extrasolar planetary systems is central to both the intellectual understanding of our origins and the cultural understanding of humanity's place in the Universe; thus it is appropriate that the goals and objectives of NASA's breakthrough Origins program emphasize the study of planetary systems, with a focus on the search for habitable planets. We propose an ambitious research program that will use SIM - the first major mission of the Origins program - to explore planetary systems in our Galactic neighborhood. Our program is a novel two-tiered SIM survey of nearby stars that exploits the capabilities of SIM to achieve two scientific objectives: (i) to identify Earth-like planets in habitable regions around nearby Sunlike stars: and (ii) to explore the nature and evolution of planetary systems in their full variety. The first of these objectives was recently recommended by the Astronomy and Astrophysics Survey Committee (the McKee-Taylor Committee) as a prerequisite for the development of the Terrestrial Planet Finder mission later in the decade. Our program combines this two-part survey with preparatory and contemporaneous research designed to maximize the scientific return from the limited and thus precious observing resources of SIM.

  18. Migration & Extra-solar Terrestrial Planets: Watering the Planets

    NASA Astrophysics Data System (ADS)

    Carter-Bond, Jade C.; O'Brien, David P.; Raymond, Sean N.

    2014-04-01

    A diverse range of terrestrial planet compositions is believed to exist within known extrasolar planetary systems, ranging from those that are relatively Earth-like to those that are highly unusual, dominated by species such as refractory elements (Al and Ca) or C (as pure C, TiC and SiC)(Bond et al. 2010b). However, all prior simulations have ignored the impact that giant planet migration during planetary accretion may have on the final terrestrial planetary composition. Here, we combined chemical equilibrium models of the disk around five known planetary host stars (Solar, HD4203, HD19994, HD213240 and Gl777) with dynamical models of terrestrial planet formation incorporating various degrees of giant planet migration. Giant planet migration is found to drastically impact terrestrial planet composition by 1) increasing the amount of Mg-silicate species present in the final body; and 2) dramatically increasing the efficiency and amount of water delivered to the terrestrial bodies during their formation process.

  19. MASS-RADIUS RELATIONSHIPS FOR VERY LOW MASS GASEOUS PLANETS

    SciTech Connect

    Batygin, Konstantin; Stevenson, David J.

    2013-05-20

    Recently, the Kepler spacecraft has detected a sizable aggregate of objects, characterized by giant-planet-like radii and modest levels of stellar irradiation. With the exception of a handful of objects, the physical nature, and specifically the average densities, of these bodies remain unknown. Here, we propose that the detected giant planet radii may partially belong to planets somewhat less massive than Uranus and Neptune. Accordingly, in this work, we seek to identify a physically sound upper limit to planetary radii at low masses and moderate equilibrium temperatures. As a guiding example, we analyze the interior structure of the Neptune-mass planet Kepler-30d and show that it is acutely deficient in heavy elements, especially compared with its solar system counterparts. Subsequently, we perform numerical simulations of planetary thermal evolution and in agreement with previous studies, show that generally, 10-20 M{sub Circled-Plus }, multi-billion year old planets, composed of high density cores and extended H/He envelopes can have radii that firmly reside in the giant planet range. We subject our results to stability criteria based on extreme ultraviolet radiation, as well as Roche-lobe overflow driven mass-loss and construct mass-radius relationships for the considered objects. We conclude by discussing observational avenues that may be used to confirm or repudiate the existence of putative low mass, gas-dominated planets.

  20. 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

  1. The NGCSU Extrasolar Planet Transit Project

    NASA Astrophysics Data System (ADS)

    Jones, J. H.

    2000-12-01

    Since the first published reports of the detection of the extra-solar planet transit of HD 209458 (Henry, et al. 2000, ApJ, 529, L41; Charbonneau, et al. 2000, ApJ, 529, L45), we have been attempting to detect and measure the transits with high enough accuracy for useful data analysis of the light curves. Our goal is to improve our observational and data analysis techniques, and hopefully upgrade our equipment, until we are able to reliably acquire milli-magnitude multiband photometry of HD 209458 both on and off transit. We believe our observatory can fill a useful niche in the long term monitoring of HD 209458 and other such planet-transit stars that will surely be discovered in the future. There is also an important astronomy education component to our project as well. The chance for our undergraduate Physics majors to participate in important publishable research can be a great motivating factor for them to continue their academic careers into graduate school. Furthermore, the fact that they have participated in such a project makes our graduates more "marketable" to the graduate schools. We also have a high school teacher and student currently participating in our project. This shows the project is useful in providing astronomy outreach beyond our local institution. We report here on our first detection of the planet-transit during the night of August 15-16, 2000 and also present our data from a series of transits during the month of October, 2000. Finally, we will present the project's current status at the time of the meeting.

  2. Tidal Constraints on the Masses of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Trilling, D. E.

    2000-07-01

    Tidal theory predicts that the orbits of close extrasolar giant planets will circularize on timescales that can be comparable to the ages of those systems. Additionally, planets that are close enough and massive enough can spin up their central stars. Since the eccentricities of extrasolar planet orbits are determined by the radial velocity technique and since stellar rotation rates are observed, or at least derived, limits on the masses of close extrasolar planets can be placed. We find upper limits on the masses of eight extrasolar planets, including limiting the masses of υ And b, HD 75289b, HD 187123b, and 51 Peg b to less than 1.48, 1.21, 0.59, and 0.51 Jupiter masses, respectively. There is a contradiction in the constrained mass of HD 217107b, in that its eccentricity is apparently too high. This anomalously high eccentricity could be real and caused by other planets in that system; or it could be an artifact of fitting a one-orbit solution to multiplanet data. The tidal limits placed on all these extrasolar planets are only as good as the knowledge of the stellar parameters (age, rotation period), which in some cases is not very good; better detailed knowledge of stars hosting planets will be necessary.

  3. Discovering Extrasolar Planets with Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Wambsganss, J.

    2016-06-01

    An astronomical survey is commonly understood as a mapping of a large region of the sky, either photometrically (possibly in various filters/wavelength ranges) or spectroscopically. Often, catalogs of objects are produced/provided as the main product or a by-product. However, with the advent of large CCD cameras and dedicated telescopes with wide-field imaging capabilities, it became possible in the early 1990s, to map the same region of the sky over and over again. In principle, such data sets could be combined to get very deep stacked images of the regions of interest. However, I will report on a completely different use of such repeated maps: Exploring the time domain for particular kinds of stellar variability, namely microlens-induced magnifications in search of exoplanets. Such a time-domain microlensing survey was originally proposed by Bohdan Paczynski in 1986 in order to search for dark matter objects in the Galactic halo. Only a few years later three teams started this endeavour. I will report on the history and current state of gravitational microlensing surveys. By now, routinely 100 million stars in the Galactic Bulge are monitored a few times per week by so-called survey teams. All stars with constant apparent brightness and those following known variability patterns are filtered out in order to detect the roughly 2000 microlensing events per year which are produced by stellar lenses. These microlensing events are identified "online" while still in their early phases and then monitored with much higher cadence by so-called follow-up teams. The most interesting of such events are those produced by a star-plus-planet lens. By now of order 30 exoplanets have been discovered by these combined microlensing surveys. Microlensing searches for extrasolar planets are complementary to other exoplanet search techniques. There are two particular advantages: The microlensing method is sensitive down to Earth-mass planets even with ground-based telecopes, and it

  4. GJ 436 Extrasolar Planet Transit Campaign

    NASA Astrophysics Data System (ADS)

    Price, Aaron; Henden, Arne

    2008-02-01

    A campaign, headed by Dr. Greg Laughlin (transitsearch.org and University of California, Santa Cruz) has been initiated to observe GJ 436 for transits of extrasolar planets. Precise multicolor photometry, carefully reduced but not transformed, is requested of AAVSO observers. The GJ 436 system is m(V)=~10.7; the expected transit length is ~1 hour; the transit depth is less than 0.1 magnitude (~0.006 mag). Dr. Laughlin provides the following transit period and ephemeris: P = 2.643901 days T_mid = 2454222.6157 HJD (02:46:36.48 UT May 2, 2007) The next transit is scheduled for February 14, 2008 from 06:49 to 07:47 UT. The parent system is very red (M3V); so including airmass values will be very important. Links to information on comparison stars, finder charts, airmass calculation, and other aspects of this campaign, as well as advice on making the photometric observations, is available in the Alert Notice. Observations submitted to the AAVSO International Database as GJ 436.

  5. The Discovery of Extrasolar Planets via Transits

    NASA Astrophysics Data System (ADS)

    Dunham, Edward W.; Borucki, W. J.; Jenkins, J. M.; Batalha, N. M.; Caldwell, D. A.; Mandushev, G.

    2014-01-01

    The goal of detecting extrasolar planets has been part of human thought for many centuries and several plausible approaches for detecting them have been discussed for many decades. At this point in history the two most successful approaches have been the reflex radial velocity and transit approaches. These each have the additional merit of corroborating a discovery by the other approach, at least in some cases, thereby producing very convincing detections of objects that can't be seen. In the transit detection realm the key enabling technical factors were development of: - high quality large area electronic detectors - practical fast optics with wide fields of view - automated telescope systems - analysis algorithms to correct for inadequacies in the instrumentation - computing capability sufficient to cope with all of this This part of the equation is relatively straightforward. The more important part is subliminal, namely what went on in the minds of the proponents and detractors of the transit approach as events unfolded. Three major paradigm shifts had to happen. First, we had to come to understand that not all solar systems look like ours. The motivating effect of the hot Jupiter class of planet was profound. Second, the fact that CCD detectors can be much more stable than anybody imagined had to be understood. Finally, the ability of analysis methods to correct the data sufficiently well for the differential photometry task at hand had to be understood by proponents and detractors alike. The problem of capturing this changing mind-set in a collection of artifacts is a difficult one but is essential for a proper presentation of this bit of history.

  6. Fast migration of low-mass planets in radiative discs

    NASA Astrophysics Data System (ADS)

    Pierens, A.

    2015-12-01

    Low-mass planets are known to undergo Type I migration and this process must have played a key role during the evolution of planetary systems. Analytical formulae for the disc torque have been derived assuming that the planet evolves on a fixed circular orbit. However, recent work has shown that in isothermal discs, a migrating protoplanet may also experience dynamical corotation torques that scale with the planet drift rate. The aim of this study is to examine whether dynamical corotation torques can also affect the migration of low-mass planets in non-isothermal discs. We performed 2D radiative hydrodynamical simulations to examine the orbital evolution outcome of migrating protoplanets as a function of disc mass. We find that a protoplanet can enter a fast migration regime when it migrates in the direction set by the entropy-related horseshoe drag and when the Toomre stability parameter is less than a threshold value below which the horseshoe region contracts into a tadpole-like region. In that case, an underdense trapped region appears near the planet, with an entropy excess compared to the ambient disc. If the viscosity and thermal diffusivity are small enough so that the entropy excess is conserved during migration, the planet then experiences strong corotation torques arising from the material flowing across the planet orbit. During fast migration, we observe that a protoplanet can pass through the zero-torque line predicted by static torques. We also find that fast migration may help in disrupting the mean-motion resonances that are formed by convergent migration of embryos.

  7. THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. II. MIGRATION SIMULATIONS

    SciTech Connect

    Carter-Bond, Jade C.; O'Brien, David P.; Raymond, Sean N.

    2012-11-20

    Prior work has found that a variety of terrestrial planetary compositions are expected to occur within known extrasolar planetary systems. However, such studies ignored the effects of giant planet migration, which is thought to be very common in extrasolar systems. Here we present calculations of the compositions of terrestrial planets that formed in dynamical simulations incorporating varying degrees of giant planet migration. We used chemical equilibrium models of the solid material present in the disks of five known planetary host stars: the Sun, GJ 777, HD4203, HD19994, and HD213240. Giant planet migration has a strong effect on the compositions of simulated terrestrial planets as the migration results in large-scale mixing between terrestrial planet building blocks that condensed at a range of temperatures. This mixing acts to (1) increase the typical abundance of Mg-rich silicates in the terrestrial planets' feeding zones and thus increase the frequency of planets with Earth-like compositions compared with simulations with static giant planet orbits, and (2) drastically increase the efficiency of the delivery of hydrous phases (water and serpentine) to terrestrial planets and thus produce waterworlds and/or wet Earths. Our results demonstrate that although a wide variety of terrestrial planet compositions can still be produced, planets with Earth-like compositions should be common within extrasolar planetary systems.

  8. The Compositional Diversity of Extrasolar Terrestrial Planets. II. Migration Simulations

    NASA Astrophysics Data System (ADS)

    Carter-Bond, Jade C.; O'Brien, David P.; Raymond, Sean N.

    2012-11-01

    Prior work has found that a variety of terrestrial planetary compositions are expected to occur within known extrasolar planetary systems. However, such studies ignored the effects of giant planet migration, which is thought to be very common in extrasolar systems. Here we present calculations of the compositions of terrestrial planets that formed in dynamical simulations incorporating varying degrees of giant planet migration. We used chemical equilibrium models of the solid material present in the disks of five known planetary host stars: the Sun, GJ 777, HD4203, HD19994, and HD213240. Giant planet migration has a strong effect on the compositions of simulated terrestrial planets as the migration results in large-scale mixing between terrestrial planet building blocks that condensed at a range of temperatures. This mixing acts to (1) increase the typical abundance of Mg-rich silicates in the terrestrial planets' feeding zones and thus increase the frequency of planets with Earth-like compositions compared with simulations with static giant planet orbits, and (2) drastically increase the efficiency of the delivery of hydrous phases (water and serpentine) to terrestrial planets and thus produce waterworlds and/or wet Earths. Our results demonstrate that although a wide variety of terrestrial planet compositions can still be produced, planets with Earth-like compositions should be common within extrasolar planetary systems.

  9. 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

  10. Exploring Extrasolar Planetary Systems: New Observations of Extrasolar Planets Enabled by the James Webb Space Telescope

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2012-01-01

    The search for extrasolar planets has been increasingly success over the last few years. In excess of 700 systems are now known, and Kepler has approx.2500 additional candidate systems, yet to be confirmed. Recently, progress has also been made in directly imaging extrasolar planets, both from the ground and in space. In this presentation will discuss the techniques employed to discover planetary systems, and highlight the capabilities, enabled by the James Webb Space Telescope (JWST). JWST is a large 6.5 meter aperture infrared telescope that is scheduled for launch in 2018, and will allow us to transition to characterizing the properties of these extrasolar planets and the planetary systems in which they reside.

  11. Atmospheres of Low-mass Planets: The "Boil-off"

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Wu, Yanqin

    2016-02-01

    We show that, for a low-mass planet that orbits its host star within a few tenths of an AU (like the majority of the Kepler planets), the atmosphere it was able to accumulate while embedded in the protoplanetary disk may not survive unscathed after the disk disperses. This gas envelope, if more massive than a few percent of the core (with a mass below 10{M}\\oplus ), has a cooling time that is much longer than the timescale on which the planet exits the disk. As such, it could not have contracted significantly from its original size, of the order of the Bondi radius. So a newly exposed protoplanet would be losing mass via a Parker wind that is catalyzed by the stellar continuum radiation. This represents an intermediate stage of mass-loss, occurring soon after the disk has dispersed, but before the EUV/X-ray driven photoevaporation becomes relevant. The surface mass-loss induces a mass movement within the envelope that advects internal heat outward. As a result, the planet atmosphere rapidly cools down and contracts, until it has reached a radius of the order of 0.1 Bondi radius, at which time the mass-loss effectively shuts down. Within a million years after the disk disperses, we find a planet that has only about 10% of its original envelope, and a Kelvin-Helmholtz time that is much longer than its actual age. We suggest that this “boil-off” process may be partially responsible for the lack of planets above a radius of 2.5{R}\\oplus in the Kepler data, provided planet formation results in initial envelope masses of tens of percent.

  12. On the road to imaging extrasolar planets: Null results, other discoveries along the way, and signposts for the future

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric Ludwig

    I present my experiences designing, conducting, and analyzing the results from direct imaging surveys for extrasolar giant planets. Using the young, low-mass star AB Dor C, I show that models for low-mass stars and brown dwarfs at young ages are good representations of reality. I discuss the design of the Simultaneous Differential Imaging survey, and how Monte Carlo simulations of giant planet populations allow for the design of imaging surveys, including the choice of target list, that maximizes the expected yield of extrasolar planets. With the conclusion of the SDI survey, I examine how its null result for planets sets constraints on the allowable populations of long-period exoplanets, finding that fewer than 8% of sun-like stars can have planets more massive than 4M Jup between 20 and 100 AU, at 68% confidence. When I include null results from other direct imaging surveys, these constraints are further strengthened: at 68% confidence, fewer than 20% of sun-like stars can have planets more massive than 4M Jup , at orbital semi-major axes between 8.1 and 911 AU. Even when applying the mass scaling of Johnson et al. (2007), and the "cold start" planet luminosity models of Fortney et al. (2008), the results remain consistent: giant planets are rare at large separations around sun-like stars. I explain how these constraints and planet simulations were used to design the Gemini South NICI Planet-Finding Campaign survey and target list, in order to maximize the chance of NICI detecting a planet, and so giving the campaign the greatest ability to strongly constrain populations of extrasolar giant planets, even in the case of a null result. Finally, I discuss future directions for direct imaging planet searches, and the steps needed to move from existing surveys to a truly unified distribution of extrasolar planet populations.

  13. First Light from Extrasolar Planets and Implications for Astrobiology

    NASA Technical Reports Server (NTRS)

    Richardson, L. Jeremy; Seager, Sara; Harrington, Joseph; Deming, Drake

    2005-01-01

    The first light from an extrasolar planet was recently detected. These results, obtained for two transiting extrasolar planets at different infrared wavelengths, open a new era in the field of extrasolar planet detection and characterization because for the first time we can now detect planets beyond the solar system directly. Using the Spitzer Space Telescope at 24 microns, we observed the modulation of combined light (star plus planet) from the HD 209458 system as the planet disappeared behind the star during secondary eclipse and later re-emerged, thereby isolating the light from the planet. We obtained a planet-to-star ratio of 0.26% at 24 microns, corresponding to a brightness temperature of 1130 + / - 150 K. We will describe this result in detail, explain what it can tell us about the atmosphere of HD 209458 b, and discuss implications for the field of astrobiology. These results represent a significant step on the path to detecting terrestrial planets around other stars and in understanding their atmospheres in terms of composition and temperature.

  14. Exozodiacal Dust and Direct Imaging of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2008-01-01

    Direct imaging of extrasolar planets means contending with dust from extrasolar asteroids and comets. This 'exozodiacal dust' creates a structured background light that can easily outshine the light from an exoEarth and confuse a planet-search mission like TPF or TOPS. But exozodiacal dust can be both friend and foe: planets can stir dust clouds into patterns that reveal the presence of the planet and constrain its mass and orbit. I'll describe some recent research on this topic: 3-D dynamical models of dust clouds with planets and searches for exozodiacal dust with the Keck Interferometer. The author also offers a prediction for the typical zodiacal dust background found around solar analogs, based on seafloor sediment data.

  15. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    NASA Astrophysics Data System (ADS)

    1996-01-01

    both U.S. and foreign sources. The MMA will be capable of imaging planetary systems in the earliest stages of their formation. The MMA will be able to detect many more young, low-mass stellar systems and to examine them to determine if they have the disks from which planetary systems are formed. In addition, the MMA could be used to examine the properties of these disks in detail. The properties that could be examined include size, temperature, dust density and chemistry. A number of enhancements have been proposed to the MMA, including longer baselines for greater resolution, the ability to observe at higher frequencies, and greater signal bandwidth. This enhanced MMA would have the sensitivity to directly detect very young giant planets in the nearest star-forming regions, the resolving power to distinguish them from their central stars, and the ability to detect giant planets by measuring their gravitational effect upon their parent stars and thus determine their masses. The VLA, dedicated in 1980, also could contribute to the search for extrasolar planets if proposed upgrades are implemented. Though originally designed to operate at a highest frequency of 24 GHz, the VLA recently has been equipped with receivers for 40-50 GHz. Funding for receivers in this range, at a wavelength of 7 millimeters, was provided in 1993 by the government of Mexico. The VLA now has 13 of its 27 antennas equipped with these 40-50 GHz receivers. Plans for upgrading the VLA include equipping all remaining antennas with such receivers, improving its electronics, and improving its resolution by adding antennas at extended distances. The upgraded VLA will be able to study the inner parts of the dust disks surrounding young stars -- disks that are believed to be the precursors to planetary systems. The inner parts of such disks are obscured at shorter wavelengths. The enhanced VLA will be able to reveal processes occurring in these disks at scales comparable to the size of our own Solar

  16. Eccentricity versus Mass for Low-Mass Secondaries and Planets

    NASA Astrophysics Data System (ADS)

    Mazeh, Tsevi; Mayor, Michel; Latham, David W.

    1997-03-01

    Spectroscopic orbits have been reported for six unseen companions orbiting solar-type stars with minimum possible masses in the range 0.5-10 Jupiter masses. The four least massive companions, around 51 Peg, 47 UMa, 55 Cnc, and τ Boo, have nearly circular orbits, while the two most massive companions, around HD 114762 and 70 Vir, have eccentricities of 0.35 and 0.40. We compare the orbital eccentricities of these six planet candidates with the eccentricities of the planets in the solar system, of the three planets found around the pulsar PSR B1957+12, and of the low-mass secondaries in a subsample of the spectroscopic binaries from the Carney-Latham proper-motion survey. The distribution of eccentricities for the combined samples displays a striking pattern: the companions with masses smaller than about 5 Jupiter masses have circular orbits, while the more massive companions have eccentric orbits. We outline four possible scenarios that might have produced this pattern of eccentricity versus mass.

  17. Clouds in Low-mass, Low-density Planets

    NASA Astrophysics Data System (ADS)

    Morley, Caroline; Fortney, J.; Marley, M.; Kempton, E.; Visscher, C.; Zahnle, K.

    2013-10-01

    The Kepler Space Telescope has revealed huge populations of low-mass, low-density planets, but their compositions remain elusive. For example, the density of GJ 1214b is consistent with either a water-world with a water atmosphere or a rock-iron core with a H/He envelope. Other super-Earths must contain hydrogen and helium to match their observed masses and radii. To understand this population of objects, we must be able to characterize their compositions through spectroscopy. The formation of clouds in exoplanet atmospheres significantly changes their observable spectra. For exoplanets, the opacity of hazes or clouds has been invoked as a possible explanation for the observed flat transmission spectrum of transiting super-Earth GJ 1214b as well as for the strong Rayleigh scattering feature in HD 189733b, the best-studied hot Jupiter. Here, we examine the effect of clouds on low-mass, low-density exoplanet spectra. We include the condensates that are present in chemical equilibrium for objects at these temperatures (500-900 K) which include minerals like sulfides and alkali salts. The most important of these clouds are sodium sulfide, potassium chloride, and zinc sulfide. These clouds should be most prominent at low surface gravity, strongly super-solar atmospheric abundances, and at the slant viewing geometry appropriate for transits. Hence they could be quite important for affecting the transmission spectra of cool low density super-Earth and Neptune-class planets. Another class of clouds may also dramatically alter the spectra of irradiated planets: photochemical hazes. We additionally include a hydrocarbon haze layer similar to the tholin haze in Titan’s atmosphere. We calculate the location and density of the haze layer using photochemical models from Kempton et al. 2012. We present new results that show that for enhanced metallicity atmospheres, either the clouds that form in equilibrium or a hydrocarbon haze layer could become sufficiently optically thick

  18. ENHANCED INTERFEROMETRIC IDENTIFICATION OF SPECTRA IN HABITABLE EXTRASOLAR PLANETS

    SciTech Connect

    Schwartz, Eyal; Lipson, Stephen G.; Ribak, Erez N.

    2012-09-15

    An Earth-like extrasolar planet emits light that is many orders of magnitude fainter than that of the parent star. We propose a method of identifying bio-signature spectral lines in light of known extrasolar planets based on Fourier spectroscopy in the infrared, using an off-center part of a Fourier interferogram only. This results in superior sensitivity to narrower molecular-type spectral bands, which are expected in the planet spectrum but are absent in the parent star. We support this idea by numerical simulations that include photon and thermal noise, and show it to be feasible at a luminosity ratio of 10{sup -6} for a Sun-like parent star in the infrared. We also carried out a laboratory experiment to illustrate the method. The results suggest that this method should be applicable to real planet searches.

  19. Extrasolar Planets & The Power of the Dark Side

    SciTech Connect

    Charbonneau, David

    2009-04-24

    It is only in the last decade that we have direct evidence for planets orbiting nearby Sun-like stars. If such planets happen to pass in front of their stars, we are presented with a golden opportunity to learn about the nature of these objects. Measurements of the dimming of starlight and gravitational wobble allow us to derive the planetary radius and mass, and, by inference, its composition. Recently, we used the Hubble Telescope to detect and study the atmosphere of an extrasolar planet for the first time. I will describe what we have learned about these planets 

  20. Reading the Signatures of Extrasolar Planets in Debris Disks

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J.

    2009-01-01

    An extrasolar planet sculpts the famous debris dish around Fomalhaut; probably ma ny other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. But the interaction between planets and debris disks involves both orbital resonances and collisions among grains and rocks in the disks --- difficult processes to model simultanemus]y. I will describe new 3-D models of debris disk dynamics that incorporate both collisions and resonant trapping of dust for the first time, allowing us to decode debris disk images and read the signatures of the planets they contain.

  1. 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

  2. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillan, Robert S.

    1991-01-01

    Radial velocity measurements are being made to search for planets orbiting stars other than the Sun. The reflex acceleration induced on stars by planets can be sensed by measuring the small, slow changes in the line-of-site velocities of stars. To detect these planetary perturbations, the data series must be made on a uniform instrumental scale for as long as it takes a planet to orbit its star. A spectrometer of extreme stability and unprecedented sensitivity to changes in stellar radial velocities was operated.

  3. Searching for Extrasolar Planets with SIM

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    2000-01-01

    The Space Interferometry Mission (SIM) will be the first spacebased long base-line Michelson interferometer designed for precision astrometry. SIM will extend the reach of astrometry to cover the entire Galaxy, and will address a wide range of problems in Galactic structure and stellar astrophysics. It will also serve as a technology precursor for future astrophysics missions using interferometers. SIM will be a powerful tool for discovering planets around nearby stars, through detection of the reflex motion, and it will directly measure masses for the planets detected this way. It will have a single-measurement precision of 1 microarcsecond in a frame defined by nearby reference stars, enabling SIM to search for planets with masses as small as a few earth masses around the nearest star. More massive planets will be detectable to much larger distances.

  4. TRANSIT LIGHTCURVES OF EXTRASOLAR PLANETS ORBITING RAPIDLY ROTATING STARS

    SciTech Connect

    Barnes, Jason W.

    2009-11-01

    Main-sequence stars earlier than spectral-type approxF6 or so are expected to rotate rapidly due to their radiative exteriors. This rapid rotation leads to an oblate stellar figure. It also induces the photosphere to be hotter (by up to several thousand kelvin) at the pole than at the equator as a result of a process called gravity darkening that was first predicted by von Zeipel. Transits of extrasolar planets across such a non-uniform, oblate disk yield unusual and distinctive lightcurves that can be used to determine the relative alignment of the stellar rotation pole and the planet orbit normal. This spin-orbit alignment can be used to constrain models of planet formation and evolution. Orderly planet formation and migration within a disk that is coplanar with the stellar equator will result in spin-orbit alignment. More violent planet-planet scattering events should yield spin-orbit misaligned planets. Rossiter-McLaughlin measurements of transits of lower-mass stars show that some planets are spin-orbit aligned, and some are not. Since Rossiter-McLaughlin measurements are difficult around rapid rotators, lightcurve photometry may be the best way to determine the spin-orbit alignment of planets around massive stars. The Kepler mission will monitor approx10{sup 4} of these stars within its sample. The lightcurves of any detected planets will allow us to probe the planet formation process around high-mass stars for the first time.

  5. Evidence for an Anhydrous Carbonaceous Extrasolar Minor Planet

    NASA Astrophysics Data System (ADS)

    Jura, M.; Dufour, P.; Xu, S.; Zuckerman, B.; Klein, B.; Young, E. D.; Melis, C.

    2015-01-01

    Using Keck/HIRES, we report abundances of 11 different elements heavier than helium in the spectrum of Ton 345, a white dwarf that has accreted one of its own minor planets. This particular extrasolar planetesimal, which was at least 60% as massive as Vesta, appears to have been carbon-rich and water-poor; we suggest it was compositionally similar to those Kuiper Belt Objects with relatively little ice.

  6. EVIDENCE FOR AN ANHYDROUS CARBONACEOUS EXTRASOLAR MINOR PLANET

    SciTech Connect

    Jura, M.; Xu, S.; Zuckerman, B.; Klein, B.; Dufour, P.; Young, E. D.; Melis, C. E-mail: kleinb@astro.ucla.edu E-mail: dufourpa@astro.umontreal.ca E-mail: eyoung@ess.ucla.edu

    2015-01-20

    Using Keck/HIRES, we report abundances of 11 different elements heavier than helium in the spectrum of Ton 345, a white dwarf that has accreted one of its own minor planets. This particular extrasolar planetesimal, which was at least 60% as massive as Vesta, appears to have been carbon-rich and water-poor; we suggest it was compositionally similar to those Kuiper Belt Objects with relatively little ice.

  7. Bok Prize Lecture (shared) Towards a Physical Characterization of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Seager, Sara

    2004-03-01

    We have entered a new era in planetary astrophysics with well over 100 giant planets now known to orbit nearby sun-like stars. Recent theoretical and observational advances have given us new constraints on the physical characteristics of extrasolar planets, while ongoing and proposed observing programs and space missions hold great promise for the future of extrasolar planet science. I will discuss the emerging understanding of the extrasolar transiting planet HD209458b, tying together several recent observational constraints as well as key upcoming measurements.I will also briefly review scientific highlights and prospects for the future detection and study of Earth-like extrasolar planets.

  8. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillen, Robert S.

    1988-01-01

    Researchers are measuring small changes in the line-of-sight velocities of stars to detect the oscillating reflex acceleration induced by large planets. The intention is to observe enough stars for a long enough time to be able to make a statement of the probability of planets in a certain range of masses even if no planetary perturbations are detected. To make these measurements of Doppler shift with the required sensitivity, a new instrument was specifically designed, built and tested for this campaign of ground-based planet detection. The instrument is an optical spectrometer for which wavelengths are first calibrated by transmission through a tunable Fabry-Perot etalon interferometer. The intrinsic stability of the etalon and an image-scrambling fiber optic light feed provide great sensitivity to line-of-sight accelerations and immunity to systematic errors.

  9. Capture of planets into mean-motion resonances and the origins of extrasolar orbital architectures

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin

    2015-08-01

    The early stages of dynamical evolution of planetary systems are often shaped by dissipative processes that drive orbital migration. In multi-planet systems, convergent amassing of orbits inevitably leads to encounters with rational period ratios, which may result in establishment of mean-motion resonances. The success or failure of resonant capture yields exceedingly different subsequent evolutions, and thus plays a central role in determining the ensuing orbital architecture of planetary systems. In this work, we employ an integrable Hamiltonian formalism for first order planetary resonances that allows both secondary bodies to have finite masses and eccentricities, and construct a comprehensive theory for resonant capture. Particularly, we derive conditions under which orbital evolution lies within the adiabatic regime, and provide a generalized criterion for guaranteed resonant locking as well as a procedure for calculating capture probabilities when capture is not certain. Subsequently, we utilize the developed analytical model to examine the evolution of Jupiter and Saturn within the protosolar nebula, and investigate the origins of the dominantly non-resonant orbital distribution of sub-Jovian extrasolar planets. Our calculations show that the commonly observed extrasolar orbital structure can be understood if planet pairs encounter mean-motion commensurabilities on slightly eccentric (e ˜ 0.02) orbits. Accordingly, we speculate that resonant capture among low-mass planets is typically rendered unsuccessful due to subtle axial asymmetries inherent to the global structure of protoplanetary discs.

  10. Three Low-Mass Planets from the Anglo-Australian Planet Search

    NASA Astrophysics Data System (ADS)

    Tinney, C. G.; Butler, R. Paul; Marcy, Geoffrey W.; Jones, Hugh R. A.; Penny, Alan J.; McCarthy, Chris; Carter, Brad D.; Fischer, Debra A.

    2005-04-01

    We report the detection of three new low-mass planets from the Anglo-Australian Planet Search. The three parent stars of these planets are chromospherically quiet main-sequence G dwarfs with metallicities ranging from roughly solar (HD 117618 and HD 208487) to metal enriched (HD 102117). The orbital periods range from 20.8 to 130 days, the minimum masses from roughly 0.5MSat to 0.5MJup, and the eccentricities from 0.08 to 0.37, with the planet in the smallest orbit (HD 102117) having the smallest eccentricity. With semiamplitudes of 10.6-19 m s-1, these planets induce Doppler amplitudes similar to those of Jupiter analogs, albeit with shorter periods. Many of the most interesting future Doppler planets will be detected at these semiamplitude levels, placing a premium on measurement precision. The detection of such amplitudes in data extending back 6 yr gives confidence in the Anglo-Australian Planet Search's ability to detect Jupiter analogs as our time baseline extends to 12 yr. We discuss the criticality of such detections for the design of the next generation of extremely large telescopes and also highlight prospects for suitable observing strategies to push to below 1 m s-1 precisions for bright stars in a search for sub-Neptunian planets. Based on observations obtained at the Anglo-Australian Telescope, Siding Spring, Australia.

  11. Obliquity Variations of Extrasolar Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Chambers, John E.

    2004-01-01

    A planet's obliquity, which is the angle between its orbital angular momentum and its rotational angular momentum, is an important factor in determining its climate and habitability. For small obliquities, as well as obliquities close to 180 degrees, the planet receives more radiant energy from its star at equatorial latitudes than near its poles, whereas the poles are heated the most for obliquities near 90 degrees. Jacques Laskar has analyzed possible obliquity variations of the planets in our Solar System. His study also considers the same planets with different rotational periods, and the Earth without the Moon. He finds, using frequency map analysis, that the obliquity of the Earth is stabilized by the Moon, and can vary by at most a few degrees. In contrast, the obliquity of Mars can range from 0 to 60 degrees, and a hypothetical moonless Earth's axial tilt could be close to 0 degrees or as large as 85 degrees. Numerical integrations by Laskar and others have shown that Mars' obliquity indeed varies over most of its permitted range on time scales of tens of millions of years. In contrast, our analysis shows that the obliquity of a moonless Earth appears to be confined to the range of approximately 12 - 38 degrees over time scales of 100 million years. Results of ongoing longer integrations will be presented, and their implications discussed.

  12. 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

  13. 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.

  14. Views from EPOXI. Colors in Our Solar System as an Analog for Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Crow, Carolyn A.; McFadden, L. A.; Robinson, T.; Livengood, T. A.; Hewagama, T.; Barry, R. K.; Deming, L. D.; Meadows, V.; Lisse, C. M.

    2010-01-01

    With extrasolar planet detection becoming more common place, the frontiers of extrasolar planet science have moved beyond detection to the observations required to determine planetary properties. Once the existing observational challenges have been overcome, the first visible-light studies of extrasolar Earth-sized planets will likely employ filter photometry or low-resolution. spectroscopy to observe disk-integrated radiation from the unresolved planet. While spectroscopy of these targets is highly desirable, and provides the most robust form of characterization. S/N considerations presently limit spectroscopic measurements of extrasolar worlds. Broadband filter photometry will thus serve as a first line of characterization. In this paper we use Extrasolar Observation and Characterization (EPOCh) filter photometry of the Earth. Moon and Mars model spectra. and previous photometric and spectroscopic observations of a range the solar system planets. Titan, and Moon to explore the limitations of using color as a baseline for understanding extrasolar planets

  15. Model Atmospheres and Spectra of Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Marley, M. S.; Guillot, T.; Saumon, D.; Freedman, R. S.

    1996-09-01

    Of the known extrasolar giant planets, five have estimated effective temperatures below ~ 800K. We report on the application of a radiative-convective equilibrium model, originally developed to study the atmospheres of the solar jovian planets, to these objects (70 Vir b, 47 UMa b, Gl 411 b, 55 Cnc c, and HD 114762 b). The deposition of incident radiation from the various primaries and the estimated internal heat fluxes are included in the models. Condensible species are removed and clouds inserted where appropriate. To span the likely range of planet masses, a variety of surface gravities are considered for each object. Preliminary results suggest that water clouds are present in all these atmospheres except for 70 Vir b and HD 114762 b. Water marginally condenses in the atmosphere of the former while that of the latter should be essentially cloud free. Condensation of trace species (e.g. NH_4Cl and NH_4H_2PO_4) may produce thin hazes in these two cases. Thermochemical equilibrium favors NH_3 and CH_4 in all these atmospheres while N_2 and CO are favored in the atmospheres of the close-orbit, hot companions like 51 Peg b and upsilon And b. The reflected visible and thermal infrared spectra of these objects are dominated by water, methane, and ammonia absorption. We find that the 4 to 5 microns window in CH_4 and H_2O opacity is open for all of these objects. Consequently, as in the case of Jupiter and the brown dwarf Gliese 229 B, the emitted flux in this region is significantly greater than the blackbody flux for the planetary effective temperature. Thus this spectral region is favorable for the detection of extrasolar giant planets and brown dwarfs. Comparison of model spectra with observations would constrain the vertical temperature and cloud structure of these new atmospheres. Burrows et al. (this meeting) use these and other models to examine the evolution of extrasolar giant planets.

  16. Transits of Extrasolar Planets and Analysis Methods

    NASA Astrophysics Data System (ADS)

    Fritchman, Joseph

    2007-10-01

    Using Wittenberg's 10-inch refracting telescope housed in Elgar Weaver Observatory, and an ST-8XE CCD camera, the egress of the transit of planet HD209458 `b' was observed on the night of December 18^th, 2006. This transit occurs when the planet passes directly between its host star and the telescope on Earth, and the brightness of the star decreases by about 1.5%. The brightness of the stars is measured by the number of counts in pixels in images taken as 30 second exposures over a period of 64 minutes. Data analysis techniques using Diffraction Limited's MaxImDL^TM yield a standard deviation of less than .004 magnitudes using a sliding box averaging method. This means that a change in brightness can be measured of about .4% and much dimmer transits of other planets may be recorded from this telescope. Analysis methods using MathWork's MATLAB^ are being developed to gain more control over how pixels are combined to determine the brightness of stars and more effective modes of combining images.

  17. A Three-Planet Extrasolar System

    NASA Astrophysics Data System (ADS)

    Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Queloz, Didier; Udry, Stéphane; Santos, Nuno C.; Alibert, Yann; Benz, Willy; Mordasini, Christoph; Bouchy, François; Correia, Alexandre C. M.; Laskar, Jacques; Bertaux, Jean-Loup; Sivan, Jean-Pierre

    2006-06-01

    Using the ultra-precise HARPS spectro-graph on ESO’s 3.6-m telescope at La Silla, a team of astronomers1 has discovered that a nearby star is host to three Neptune-mass planets. The in-nermost planet is most probably rocky, while the outermost is the first known Neptune-mass planet to reside in the habitable zone. This unique system is likely further enriched by an asteroid belt. Z% Lovis et al. 2006, Nature 441, 305. The team is composed of Christophe Lovis, Michel Mayor, Francesco Pepe, Didier Queloz, and Stéphane Udry (Observatoire de l’Université de Genève, Switzerland), Nuno C. Santos (Observatoire de l’Uni-versité de Genève, Switzerland, Centro de Astro-nomia e Astrofisica da Universidade de Lisboa and Centro de Geofisica de Evora, Portugal), Yann Alibert, Willy Benz, Christoph Mordasini (Physikalisches Institut der Universität Bern, Switzerland), François Bouchy (Observatoire de Haute-Provence and IAP, France), Alexandre C. M. Correia (Uni-versidade de Aveiro, Portugal), Jacques Laskar (IMCCE-CNRS, Paris, France), Jean-Loup Bertaux (Service d’Aéronomie du CNRS, France), and Jean-Pierre Sivan (Laboratoire d’Astrophysique de Marseille, France).

  18. Habitable moons around extrasolar giant planets

    NASA Technical Reports Server (NTRS)

    Williams, D. M.; Kasting, J. F.; Wade, R. A.

    1997-01-01

    Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.

  19. Habitable moons around extrasolar giant planets.

    PubMed

    Williams, D M; Kasting, J F; Wade, R A

    1997-01-16

    Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere. PMID:9000072

  20. 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.

  1. Convection and plate tectonics on extrasolar planets

    NASA Astrophysics Data System (ADS)

    Sotin, C.; Grasset, O.; Schubert, G.

    2012-04-01

    The number of potential Earth-like exoplanets is still very limited compared to the overall number of detected exoplanets. But the different methods keep improving, giving hope for this number to increase significantly in the coming years. Based on the relationship between mass and radius, two of the easiest parameters that can be known for exoplanets, four categories of planets have been identified: (i) the gas giants including hot Jupiters, (ii) the icy giants that can be like their solar system cousins Uranus and Neptune or that can have lost their H2-He atmosphere and have become the so-called ocean planets, (iii) the Earth-like planets with a fraction of silicates and iron similar to that of the Earth, and (iv) the Mercury like planet that have a much larger fraction of iron. The hunt for exoplanets is very much focused on Earth-like planets because of the desire to find alien forms of life and the science goal to understand how life started and developed on Earth. One science question is whether heat transfer by subsolidus convection can lead to plate tectonics, a process that allows material to be recycled in the interior on timescales of hundreds of millions of years. Earth-like exoplanets may have conditions quite different from Earth. For example, COROT-7b is so close to its star that it is likely locked in synchronous orbit with one very hot hemisphere and one very cold hemisphere. It is also worth noting that among the three Earth-like planets of the solar system (Earth, Venus and Mars), only Earth is subject to plate tectonics at present time. Venus may have experienced plate tectonics before the resurfacing event that erased any clue that such a process existed. This study investigates some of the parameters that can influence the transition from stagnant-lid convection to mobile-lid convection. Numerical simulations of convective heat transfer have been performed in 3D spherical geometry in order to determine the stress field generated by convection

  2. THE HEAVY-ELEMENT MASSES OF EXTRASOLAR GIANT PLANETS, REVEALED

    SciTech Connect

    Miller, Neil; Fortney, Jonathan J.

    2011-08-01

    We investigate a population of transiting planets that receive relatively modest stellar insolation, indicating equilibrium temperatures <1000 K, and for which the heating mechanism that inflates hot Jupiters does not appear to be significantly active. We use structural evolution models to infer the amount of heavy elements within each of these planets. There is a correlation between the stellar metallicity and the mass of heavy elements in its transiting planet(s). It appears that all giant planets possess a minimum of {approx}10-15 Earth masses of heavy elements, with planets around metal-rich stars having larger heavy-element masses. There is also an inverse relationship between the mass of the planet and the metal enrichment (Z{sub pl}/Z{sub star}), which appears to have little dependency on the metallicity of the star. Saturn- and Jupiter-like enrichments above solar composition are a hallmark of all the gas giants in the sample, even planets of several Jupiter masses. These relationships provide an important constraint on planet formation and suggest large amounts of heavy elements within planetary H/He envelopes. We suggest that the observed correlation can soon also be applied to inflated planets, such that the interior heavy-element abundance of these planets could be estimated, yielding better constraints on their interior energy sources. We point to future directions for planetary population synthesis models and suggest future correlations. This appears to be the first evidence that extrasolar giant planets, as a class, are enhanced in heavy elements.

  3. Predicting the Atmospheric Composition of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Sharp, A. G.; Moses, J. I.; Friedson, A. J.; Fegley, B., Jr.; Marley, M. S.; Lodders, K.

    2004-01-01

    To date, approximately 120 planet-sized objects have been discovered around other stars, mostly through the radial-velocity technique. This technique can provide information about a planet s minimum mass and its orbital period and distance; however, few other planetary data can be obtained at this point in time unless we are fortunate enough to find an extrasolar giant planet that transits its parent star (i.e., the orbit is edge-on as seen from Earth). In that situation, many physical properties of the planet and its parent star can be determined, including some compositional information. Our prospects of directly obtaining spectra from extrasolar planets may improve in the near future, through missions like NASA's Terrestrial Planet Finder. Most of the extrasolar giant planets (EGPs) discovered so far have masses equal to or greater than Jupiter's mass, and roughly 16% have orbital radii less than 0.1 AU - extremely close to the parent star by our own Solar-System standards (note that Mercury is located at a mean distance of 0.39 AU and Jupiter at 5.2 AU from the Sun). Although all EGPs are expected to have hydrogen-dominated atmospheres similar to Jupiter, the orbital distance can strongly affect the planet's temperature, physical, chemical, and spectral properties, and the abundance of minor, detectable atmospheric constituents. Thermochemical equilibrium models can provide good zero-order predictions for the atmospheric composition of EGPs. However, both the composition and spectral properties will depend in large part on disequilibrium processes like photochemistry, chemical kinetics, atmospheric transport, and haze formation. We have developed a photochemical kinetics, radiative transfer, and 1-D vertical transport model to study the atmospheric composition of EGPs. The chemical reaction list contains H-, C-, O-, and N-bearing species and is designed to be valid for atmospheric temperatures ranging from 100-3000 K and pressures up to 50 bar. Here we examine

  4. The Problem of Extraterrestrial Civilizations and Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.

    2015-07-01

    The problem of extraterrestrial intelligence is the best example of multidisciplinary science. Here philosophy and religion, astronomy, radiophysics, spectrography, space flights and astronautics, geology and planetology, astroecology, chemistry and biology, history and archaeology, psychology, sociology, linguistics, diplomacy, UFOs and peculiar phenomena are involved. Among these many-sided studies, astronomers have probably displayed the most progress by discovering thousands of extrasolar planets. At present, a number of search programs are being accomplished, including those with space telescopes, and planets in so-called "habitable zone" are considered as most important ones, for which various orbital and physical parameters are being calculated. As the discovery of extraterrestrial life is the final goal, a special attention is given to Earth-like planets, for the discovery of which most sensitive technical means are necessary.

  5. ON THE FUNDAMENTAL MASS-PERIOD FUNCTIONS OF EXTRASOLAR PLANETS

    SciTech Connect

    Jiang, I.-G.; Yeh, L.-C.; Chang, Y.-C.; Hung, W.-L.

    2010-01-01

    Employing a catalog of 175 extrasolar planets (exoplanets) detected by the Doppler-shift method, we constructed the independent and coupled mass-period functions. It is the first time in this field that the selection effect is considered in the coupled mass-period functions. Our results are consistent with those of Tabachnik and Tremaine in 2002, with the major difference that we obtain a flatter mass function but a steeper period function. Moreover, our coupled mass-period functions show that about 2.5% of stars would have a planet with mass between Earth Mass and Neptune Mass, and about 3% of stars would have a planet with mass between Neptune Mass and Jupiter Mass.

  6. CALIBRATION OF EQUILIBRIUM TIDE THEORY FOR EXTRASOLAR PLANET SYSTEMS. II

    SciTech Connect

    Hansen, Brad M. S.

    2012-09-20

    We present a new empirical calibration of equilibrium tidal theory for extrasolar planet systems, extending a prior study by incorporating detailed physical models for the internal structure of planets and host stars. The resulting strength of the stellar tide produces a coupling that is strong enough to reorient the spins of some host stars without causing catastrophic orbital evolution, thereby potentially explaining the observed trend in alignment between stellar spin and planetary orbital angular momentum. By isolating the sample whose spins should not have been altered in this model, we also show evidence for two different processes that contribute to the population of planets with short orbital periods. We apply our results to estimate the remaining lifetimes for short-period planets, examine the survival of planets around evolving stars, and determine the limits for circularization of planets with highly eccentric orbits. Our analysis suggests that the survival of circularized planets is strongly affected by the amount of heat dissipated, which is often large enough to lead to runaway orbital inflation and Roche lobe overflow.

  7. The Discovery of Extrasolar Planets by Backyard Astronomers

    NASA Astrophysics Data System (ADS)

    Castellano, T.; Laughlin, G.

    2002-05-01

    The discovery since 1995 of more than 80 planets around nearby solar-like stars and the photometric measurement of a transit of the jovian mass planet orbiting the solar-like star HD 209458 (producing a more than 1% drop in brightness that lasts 3 hours) has heralded a new era in astronomy. It has now been demonstrated that small telescopes equipped with sensitive and stable electronic detectors can produce fundamental scientific discoveries regarding the frequency and nature of planets outside the solar system. The modest equipment requirements for the discovery of extrasolar planetary tran- sits of jovian mass planets in short period orbits around solar-like stars are fulfilled by commercial small aperture telescopes and CCD (charge coupled device) imagers common among amateur astronomers. With equipment already in hand and armed with target lists, observing techniques and software proce- dures developed by scientists at NASA's Ames Research Center and the Univer- sity of California at Santa Cruz, non-professional astronomers can contribute significantly to the discovery and study of planets around others stars. In this way, we may resume (after a two century interruption!) the tradition of planet discoveries by amateur astronomers begun with William Herschel's 1787 discovery of the "solar" planet Uranus.

  8. The Discovery of Extrasolar Planets by Backyard Astronomers

    NASA Technical Reports Server (NTRS)

    Castellano, Tim; Laughlin, Greg; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The discovery since 1995 of more than 80 planets around nearby solar-like stars and the photometric measurement of a transit of the jovian mass planet orbiting the solar-like star HD 209458 (producing a more than 1% drop in brightness that lasts 3 hours) has heralded a new era in astronomy. It has now been demonstrated that small telescopes equipped with sensitive and stable electronic detectors can produce fundamental scientific discoveries regarding the frequency and nature of planets outside the solar system. The modest equipment requirements for the discovery of extrasolar planetary transits of jovian mass planets in short period orbits around solar-like stars are fulfilled by commercial small aperture telescopes and CCD (charge coupled device) imagers common among amateur astronomers. With equipment already in hand and armed with target lists, observing techniques and software procedures developed by scientists at NASA's Ames Research Center and the University of California at Santa Cruz, non-professional astronomers can contribute significantly to the discovery and study of planets around others stars. In this way, we may resume (after a two century interruption!) the tradition of planet discoveries by amateur astronomers begun with William Herschel's 1787 discovery of the 'solar' planet Uranus.

  9. The Antarctic Planet Interferometer and the potential for interferometric observations of extrasolar planets from Dome C Antarctica

    NASA Technical Reports Server (NTRS)

    Swain, M. R.; Foresto, V. Coude du; Vakili, F.

    2003-01-01

    We present a concept for the Antarctic Planet Interferometer (API) and discuss the improvements in interferometric detection and characterization of extrasolar planets by exploiting the unique potential of the best accessbile site on Earth for thermal infrared interferometry.

  10. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillen, R. S.; Smith, P. H.

    1986-01-01

    Stars are observed with a ground-based instrument designed to measure small changes in the line-of-sight velocities. The purpose of the observations is to detect large planets by the oscillatory reflex motion they induce on the stars they are orbiting. The instrument is an optical spectrometer for which wavelengths are first calibrated by transmission through a tunable Fabry-Perot etalon interferometer. Changes in the line-of-sight velocities are revealed by changes in the Doppler shift of the absorption-line spectra of stars. The scrambling of incident light by an optical fiber and the stability of wavelength calibration by a tilt-tunable Fabry-Perot etalon provide immunity to systematic errors that historically have effected more conventional radial velocity spectrographs. A cross-dispersed echelle spectrograph spatially separates the orders of constructive interference transmitted through the etalon. Selecting several echelle diffraction orders in the vicinity of 4250 to 4750 A, which are imaged on a CCD, about 350 points on the profile of the stellar spectrum are sampled by successive orders of interferometric transmission through the etalon.

  11. CALIBRATION OF EQUILIBRIUM TIDE THEORY FOR EXTRASOLAR PLANET SYSTEMS

    SciTech Connect

    Hansen, Brad M. S.

    2010-11-01

    We provide an 'effective theory' of tidal dissipation in extrasolar planet systems by empirically calibrating a model for the equilibrium tide. The model is valid to high order in eccentricity and parameterized by two constants of bulk dissipation-one for dissipation in the planet and one for dissipation in the host star. We are able to consistently describe the distribution of extrasolar planetary systems in terms of period, eccentricity, and mass (with a lower limit of a Saturn mass) with this simple model. Our model is consistent with the survival of short-period exoplanet systems, but not with the circularization period of equal mass stellar binaries, suggesting that the latter systems experience a higher level of dissipation than exoplanet host stars. Our model is also not consistent with the explanation of inflated planetary radii as resulting from tidal dissipation. The paucity of short-period planets around evolved A stars is explained as the result of enhanced tidal inspiral resulting from the increase in stellar radius with evolution.

  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. A rocky planet transiting a nearby low-mass star

    NASA Astrophysics Data System (ADS)

    Berta-Thompson, Zachory K.; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R.; Dittmann, Jason; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michael; Jehin, Emmanuel; Stark, Antony; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christoph; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno; Udry, Stéphane; Wunsche, Anael

    2015-12-01

    Results from Kepler indicate that M dwarfs host, on average, at least 1.4 planets between 0.5 and 1.5 Earth radii per star. Yet, the closest small planets known to transit M dwarfs have been too distant to allow Doppler measurements of their masses or spectroscopic studies of their atmospheres. Here, we announce a new planet discovered by the MEarth-South observatory, an Earth-size planet transiting an M dwarf that is only 12 pc away. The density of the planet, determined from radial velocity observations with HARPS, is consistent with an Earth-like rock/iron composition. With an equilibrium temperature of 530K (assuming a Bond albedo of 0.3), this planet is cooler than most other rocky planets with measured densities. Although too hot to be habitable, it is cool enough that it may have retained a substantial atmosphere over its lifetime. Thanks to the star's proximity and its diminutive size of only 1/5th the radius of the Sun, this new world likely provides the first opportunity for our community to spectroscopically examine the atmosphere of a terrestrial exoplanet. We estimate that JWST could secure high signal-to-noise spectra of the planet's atmosphere, both in transmission during transit and in emission at secondary eclipse.

  14. ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON

    SciTech Connect

    Visscher, Channon; Lodders, Katharina; Fegley, Bruce E-mail: lodders@wustl.ed

    2010-06-20

    We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our equilibrium results are thus independent of any particular model atmosphere. The condensation of Fe metal strongly affects iron chemistry by efficiently removing Fe-bearing species from the gas phase. Monatomic Fe is the most abundant Fe-bearing gas throughout the atmospheres of EGPs and L dwarfs, and in the deep atmospheres of giant planets and T dwarfs. Mg- and Si-bearing gases are effectively removed from the atmosphere by forsterite (Mg{sub 2}SiO{sub 4}) and enstatite (MgSiO{sub 3}) cloud formation. Monatomic Mg is the dominant magnesium gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Silicon monoxide (SiO) is the most abundant Si-bearing gas in the deep atmospheres of brown dwarfs and EGPs, whereas SiH{sub 4} is dominant in the deep atmosphere of Jupiter and other gas giant planets. Several other Fe-, Mg-, and Si-bearing gases become increasingly important with decreasing effective temperature. In principle, a number of Fe, Mg, and Si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres.

  15. Search for Low-Mass Planets Around Late-M Dwarfs Using IRD

    NASA Astrophysics Data System (ADS)

    Omiya, Masashi; Sato, Bun'ei; Harakawa, Hiroki; Kuzuhara, Masayuki; Hirano, Teruyuki; Narita, Norio

    2014-04-01

    We have a plan to conduct a Doppler planet search for low-mass planets around nearby middle-to-late M dwarfs using IRD. IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. We expect to achieve the accuracy of the radial velocity measurements of 1 m/s using IRD with a frequency comb as a wavelengh calibrator. Thus, we would detect super-Earths in habitable zone and low-mass rocky planets in close-in orbits around late-M dwarfs. In this survey, we aim to understand and discuss statistical properties of low-mass planets around low-mass M dwarfs compared with those derived from theoretical simulations.

  16. THE SURVIVAL OF WATER WITHIN EXTRASOLAR MINOR PLANETS

    SciTech Connect

    Jura, M.; Xu, S. E-mail: xsynju@gmail.co

    2010-11-15

    We compute that extrasolar minor planets can retain much of their internal H{sub 2}O during their host star's red giant evolution. The eventual accretion of a water-rich body or bodies onto a helium white dwarf might supply an observable amount of atmospheric hydrogen, as seems likely for GD 362. More generally, if hydrogen pollution in helium white dwarfs typically results from accretion of large parent bodies rather than interstellar gas as previously supposed, then H{sub 2}O probably constitutes at least 10% of the aggregate mass of extrasolar minor planets. One observational test of this possibility is to examine the atmospheres of externally polluted white dwarfs for oxygen in excess of that likely contributed by oxides such as SiO{sub 2}. The relatively high oxygen abundance previously reported in GD 378 can be explained plausibly but not uniquely by accretion of an H{sub 2}O-rich parent body or bodies. Future ultraviolet observations of white dwarf pollutions can serve to investigate the hypothesis that environments with liquid water that are suitable habitats for extremophiles are widespread in the Milky Way.

  17. 2008 HI STAR Projects: Comets, Asteroids and Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Kadooka, Mary Ann; Garland, C.; Nassir, M.; Moskovitz, N.; Johnson, J.; Pittichova, J.; Meech, K. J.

    2008-09-01

    The Hawaii Student/Teacher Astronomy Research (HI STAR) residential summer program strives to equip middle and high school students with the necessary research skills and background to conduct original research projects. Students are recruited through the mini-workshops conducted on the islands of Molokai, Maui, Kauai and Oahu. For one week in June, the students with a few teachers thrive on morning physics/astronomy lectures and afternoon image processing and photometry/light curve activities. They work in groups with astronomer mentors on comet, asteroid, galaxy, nebulae, variable star and extrasolar planet projects using image data sets. They also learn to do remote observing with 2 meter Faulkes Telescope on Haleakala Maui and 16 inch DeKalb Observatory Telescope in Auburn, Indiana. The asteroid, comet and extrasolar planet projects will be highlighted with slides taken from the students’ presentations on what they had accomplished. We will also discuss how these projects are being expanded upon for fall, 2008, to be ready for 2009 Science Fair entry. This network of roles and responsibilities of our astronomer mentors, teacher advisers and student participants has been developing to ensure exemplary astronomy research projects. Funding and support for this program has come from NASA IDEAS grant, NASA Astrobiology Institute, Las Cumbres Observatory Global Telescope, DeKalb Observatory, and a private donor.

  18. 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.

  19. 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

  20. 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.

  1. A rocky planet transiting a nearby low-mass star.

    PubMed

    Berta-Thompson, Zachory K; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R; Dittmann, Jason A; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michaël; Jehin, Emmanuël; Stark, Antony A; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno C; Udry, Stéphane; Wünsche, Anaël

    2015-11-12

    M-dwarf stars--hydrogen-burning stars that are smaller than 60 per cent of the size of the Sun--are the most common class of star in our Galaxy and outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per star. The nearest such planets known to transit their star are 39 parsecs away, too distant for detailed follow-up observations to measure the planetary masses or to study their atmospheres. Here we report observations of GJ 1132b, a planet with a size of 1.2 Earth radii that is transiting a small star 12 parsecs away. Our Doppler mass measurement of GJ 1132b yields a density consistent with an Earth-like bulk composition, similar to the compositions of the six known exoplanets with masses less than six times that of the Earth and precisely measured densities. Receiving 19 times more stellar radiation than the Earth, the planet is too hot to be habitable but is cool enough to support a substantial atmosphere, one that has probably been considerably depleted of hydrogen. Because the host star is nearby and only 21 per cent the radius of the Sun, existing and upcoming telescopes will be able to observe the composition and dynamics of the planetary atmosphere. PMID:26560298

  2. A rocky planet transiting a nearby low-mass star

    NASA Astrophysics Data System (ADS)

    Berta-Thompson, Zachory K.; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R.; Dittmann, Jason A.; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michaël; Jehin, Emmanuël; Stark, Antony A.; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno C.; Udry, Stéphane; Wünsche, Anaël

    2015-11-01

    M-dwarf stars—hydrogen-burning stars that are smaller than 60 per cent of the size of the Sun—are the most common class of star in our Galaxy and outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per star. The nearest such planets known to transit their star are 39 parsecs away, too distant for detailed follow-up observations to measure the planetary masses or to study their atmospheres. Here we report observations of GJ 1132b, a planet with a size of 1.2 Earth radii that is transiting a small star 12 parsecs away. Our Doppler mass measurement of GJ 1132b yields a density consistent with an Earth-like bulk composition, similar to the compositions of the six known exoplanets with masses less than six times that of the Earth and precisely measured densities. Receiving 19 times more stellar radiation than the Earth, the planet is too hot to be habitable but is cool enough to support a substantial atmosphere, one that has probably been considerably depleted of hydrogen. Because the host star is nearby and only 21 per cent the radius of the Sun, existing and upcoming telescopes will be able to observe the composition and dynamics of the planetary atmosphere.

  3. 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.

  4. Exploring extrasolar worlds: from gas giants to terrestrial habitable planets.

    PubMed

    Tinetti, Giovanna; Griffith, Caitlin A; Swain, Mark R; Deroo, Pieter; Beaulieu, Jean Philippe; Vasisht, Gautam; Kipping, David; Waldmann, Ingo; Tennyson, Jonathan; Barber, Robert J; Bouwman, Jeroen; Allard, Nicole; Brown, Linda R

    2010-01-01

    Almost 500 extrasolar planets have been found since the discovery of 51 Peg b by Mayor and Queloz in 1995. The traditional field of planetology has thus expanded its frontiers to include planetary environments not represented in our Solar System. We expect that in the next five years space missions (Corot, Kepler and GAIA) or ground-based detection techniques will both increase exponentially the number of new planets discovered and lower the present limit of a approximately 1.9 Earth-mass object [e.g. Mayor et al., Astron. Astrophys., 2009, 507, 487]. While the search for an Earth-twin orbiting a Sun-twin has been one of the major goals pursued by the exoplanet community in the past years, the possibility of sounding the atmospheric composition and structure of an increasing sample of exoplanets with current telescopes has opened new opportunities, unthinkable just a few years ago. As a result, it is possible now not only to determine the orbital characteristics of the new bodies, but moreover to study the exotic environments that lie tens of parsecs away from us. The analysis of the starlight not intercepted by the thin atmospheric limb of its planetary companion (transit spectroscopy), or of the light emitted/reflected by the exoplanet itself, will guide our understanding of the atmospheres and the surfaces of these extrasolar worlds in the next few years. Preliminary results obtained by interpreting current atmospheric observations of transiting gas giants and Neptunes are presented. While the full characterisation of an Earth-twin might requires a technological leap, our understanding of large terrestrial planets (so called super-Earths) orbiting bright, later-type stars is within reach by current space and ground telescopes. PMID:21302557

  5. THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. I. IN SITU SIMULATIONS

    SciTech Connect

    Bond, Jade C.; Lauretta, Dante S.; O'Brien, David P.

    2010-06-01

    Extrasolar planet host stars have been found to be enriched in key planet-building elements. These enrichments have the potential to drastically alter the composition of material available for terrestrial planet formation. Here, we report on the combination of dynamical models of late-stage terrestrial planet formation within known extrasolar planetary systems with chemical equilibrium models of the composition of solid material within the disk. This allows us to determine the bulk elemental composition of simulated extrasolar terrestrial planets. A wide variety of resulting planetary compositions are found, ranging from those that are essentially 'Earth like', containing metallic Fe and Mg silicates, to those that are dominated by graphite and SiC. This shows that a diverse range of terrestrial planets may exist within extrasolar planetary systems.

  6. GIANT PLANET FORMATION BY DISK INSTABILITY IN LOW MASS DISKS?

    SciTech Connect

    Boss, Alan P.

    2010-12-20

    Forming giant planets by disk instability requires a gaseous disk that is massive enough to become gravitationally unstable and able to cool fast enough for self-gravitating clumps to form and survive. Models with simplified disk cooling have shown the critical importance of the ratio of the cooling to the orbital timescales. Uncertainties about the proper value of this ratio can be sidestepped by including radiative transfer. Three-dimensional radiative hydrodynamics models of a disk with a mass of 0.043 M{sub sun} from 4 to 20 AU in orbit around a 1 M{sub sun} protostar show that disk instabilities are considerably less successful in producing self-gravitating clumps than in a disk with twice this mass. The results are sensitive to the assumed initial outer disk (T{sub o}) temperatures. Models with T{sub o} = 20 K are able to form a single self-gravitating clump, whereas models with T{sub o} = 25 K form clumps that are not quite self-gravitating. These models imply that disk instability requires a disk with a mass of at least {approx}0.043 M{sub sun} inside 20 AU in order to form giant planets around solar-mass protostars with realistic disk cooling rates and outer-disk temperatures. Lower mass disks around solar-mass protostars must rely upon core accretion to form inner giant planets.

  7. Direct Imaging Search for Extrasolar Planets in the Pleiades

    NASA Technical Reports Server (NTRS)

    Yamamoto, Kodai; Matsuo, Taro; Shibai, Hiroshi; Itoh, Yoichi; Konishi, Mihokko; Sudo, Jun; Tanii, Ryoko; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki; Hashimoto, Jun; Kusakabe, Nobuhiko; Abe, Lyn; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph; Currie, Thayne; Egner, Sebastian E,; Feldt, Markus; Goto, Miwa; Grady, Carol; Guyon, Olivier; Hayano, Yutaka; McElwain, Mike; Serabyn, Eugene

    2013-01-01

    We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the H and K(sub S) bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the H band around 9 stars. Five of these 13 were confirmed to be background stars by measurement of their proper motion. One was not found in the second epoch observation, and thus was not a background or companion object. One had multi-epoch images, but the precision of its proper motion was not sufficient to conclude whether it was a background object. Four other candidates are waiting for second-epoch observations to determine their proper motion. Finally, the remaining two were confirmed to be 60 M(sub J) brown dwarf companions orbiting around HD 23514 (G0) and HII 1348 (K5), respectively, as had been reported in previous studies. In our observations, the average detection limit for a point source was 20.3 mag in the H band beyond 1.'' 5 from the central star. On the basis of this detection limit, we calculated the detection efficiency to be 90% for a planet with 6 to 12 Jovian masses and a semi-major axis of 50–1000 AU. For this reason we extrapolated the distribution of the planet mass and the semi-major axis derived from radial velocity observations, and adopted the planet evolution model Baraffe et al. (2003, A&A, 402, 701). Since there was no detection of a planet, we estimated the frequency of such planets to be less than 17.9% (2 sigma) around one star of the Pleiades cluster.

  8. ON THE ANOMALOUS RADII OF THE TRANSITING EXTRASOLAR PLANETS

    SciTech Connect

    Laughlin, Gregory; Crismani, Matteo

    2011-03-01

    We present a systematic evaluation of the agreement between the observed radii of 90 well-characterized transiting extrasolar giant planets and their corresponding model radii. Our model radii are drawn from previously published calculations of coreless giant planets that have attained their asymptotic radii, and which have been tabulated for a range of planet masses and equilibrium temperatures. (We report a two-dimensional polynomial fitting function that accurately represents the models.) As expected, the model radii provide a statistically significant improvement over a null hypothesis that the sizes of giant planets are completely independent of mass and effective temperature. As is well known, however, fiducial models provide an insufficient explanation; the planetary radius anomalies, R{identical_to}R{sub obs}-R{sub pred}, are strongly correlated with planetary equilibrium temperature. We find that the radius anomalies have a best-fit dependence, R{proportional_to}T{sub eff}{sup {alpha}}, with {alpha} = 1.4 {+-} 0.6. Incorporating this relation into the model radii leads to substantially less scatter in the radius correlation. The extra temperature dependence represents an important constraint on theoretical models for hot Jupiters. Using simple scaling arguments, we find support for the hypothesis of Batygin and Stevenson that this correlation can be attributed to a planetary heating mechanism that is mediated by magnetohydrodynamic coupling between the planetary magnetic field and near-surface flow that is accompanied by ohmic dissipation at adiabatic depth. Additionally, we find that the temperature dependence is likely too strong to admit kinetic heating as the primary source of anomalous energy generation within the majority of the observed transiting planets.

  9. Securing the Extremely Low-Densities of Low-Mass Planets Characterized by Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Ford, Eric B.

    2015-12-01

    Transit timing variations (TTVs) provide an excellent tool to characterize the masses and orbits of dozens of small planets, including many at orbital periods beyond the reach of both Doppler surveys and photoevaporation-induced atmospheric loss. Dynamical modeling of these systems has identified low-mass planets with surprisingly large radii and low densities (e.g., Kepler-79d, Jontof-Hutter et al. 2014; Kepler-51, Masuda 2014; Kepler-87c, Ofir et al. 2014). Additional low-density, low-mass planets will likely become public before ESS III (Jontof-Hutter et al. in prep). Collectively, these results suggest that very low density planets with masses of 2-6 MEarth are not uncommon in compact multiple planet systems. Some astronomers have questioned whether there could be an alternative interpretation of the TTV observations. Indeed, extraordinary claims require extraordinary evidence. While the physics of TTVs is rock solid, the statistical analysis of Kepler observations can be challenging, due to the complex interactions between model parameters and high-dimensional parameter spaces that must be explored. We summarize recent advances in computational statistics that enable robust characterization of planetary systems using TTVs. We present updated analyses of a few particularly interesting systems and discuss the implications for the robustness of extremely low densities for low-mass planets. Such planets pose an interesting challenge for planet formation theory and are motivating detailed theoretical studies (e.g., Lee & Chiang 2015 and associated ESS III abstracts).

  10. UMBRAS: a matched occulter and telescope for imaging extrasolar planets

    NASA Astrophysics Data System (ADS)

    Schultz, Alfred B.; Jordan, Ian J.; Kochte, Mark; Fraquelli, Dorothy A.; Bruhweiler, Fred; Hollis, Jan M.; Carpenter, Kenneth G.; Lyon, Richard G.; DiSanti, Mike A.; Miskey, Cherie L.; Leitner, Jesse; Burns, Richard D.; Starin, Scott R.; Rodrigue, Melodi; Fadali, M. S.; Skelton, Dennis L.; Hart, Helen M.; Hamilton, Forrest C.; Cheng, Kwang-Ping

    2003-02-01

    We describe a 1-meter space telescope plus free-flying occulter craft mission that would provide direct imaging and spectroscopic observations of Jovian and Uranus-sized planets about nearby stars not detectable by Doppler techniques. The Doppler technique is most sensitive for the detection of massive, close-in extrasolar planets while the use of a free-flying occulter would make it possible to image and study stellar systems with planets comparable to our own Solar System. Such a mission with a larger telescope has the potential to detect earth-like planets. Previous studies of free-flying occulters reported advantages in having the occulting spot outside the telescope compared to a classical coronagraph onboard a space telescope. Using an external occulter means light scatter within the telescope is reduced due to fewer internal obstructions and less light entering the telescope and the polishing tolerances of the primary mirror and the supporting optics can be less stringent, thereby providing higher contrast and fainter detection limits. In this concept, the occulting spot is positioned over the star by translating the occulter craft, at distances of 1,000 to 15,000 kms from the telescope, on the sky instead of by moving the telescope. Any source within the telescope field-of-view can be occulted without moving the telescope. In this paper, we present our current concept for a 1-m space telescope matched to a free-flying occulter, the Umbral Missions Blocking Radiating Astronomical Sources (UMBRAS) space mission. An UMBRAS space mission consists of a Solar Powered Ion Driven Eclipsing Rover (SPIDER) occulter craft and a matched (apodized) telescope. The occulter spacecraft would be semi-autonomous, with its own propulsion systems, internal power (solar cells), communications, and navigation capability. Spacecraft rendezvous and formation flying would be achieved with the aid of telescope imaging, RF or laser ranging, celestial navigation inputs, and formation

  11. Extrasolar Giant Planet in Earth-like Orbit

    NASA Astrophysics Data System (ADS)

    1999-07-01

    Discovery from a Long-term Project at La Silla A new extrasolar planet has been found at the ESO La Silla Observatory as a companion to iota Horologii (iota Hor) . This 5.4-mag solar-type star is located at a distance of 56 light-years and is just visible to the unaided eye in the southern constellation Horologium (The Pendulum Clock). The discovery is the result of a long-term survey of forty solar-type stars that was begun in November 1992. It is based on highly accurate measurements of stellar radial velocities, i.e. the speed with which a star moves along the line of sight. The presence of a planet in orbit around a star is inferred from observed, regular changes of this velocity, as the host star and its planet revolve around a common center of gravity. Since in all cases the star is much heavier than the planet, the resulting velocity variations of the star are always quite small. The team that found the new planet, now designated iota Hor b , consists of Martin Kürster , Michael Endl and Sebastian Els (ESO-Chile), Artie P. Hatzes and William D. Cochran (University of Texas, Austin, USA), and Stefan Döbereiner and Konrad Dennerl (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany). Iodine cell provides very accurate velocity measurements iota Hor b represents the first discovery of an extrasolar planet with an ESO instrument [1]. The finding is based on data obtained with ESO's highest-resolution spectrograph, the Coudé Echelle Spectrometer (CES) at the 1.4-m Coudé Auxiliary Telescope (CAT). While this telescope has recently been decommissioned, the CES instrument is now coupled via an optical fiber link to the larger ESO 3.6-m telescope, thus permitting the continuation of this survey. The high precision radial velocity measurements that are necessary for a study of this type were achieved by means of a special calibration technique. It incorporates an iodine gas absorption cell and sophisticated data modelling. The cell is used like

  12. Search for Cyclotron-maser Radio Emission from Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Dulk, G. A.; Leblanc, Y.; Bastian, T. S.

    1997-07-01

    There is reason to believe that extrasolar planets and/or brown dwarfs of mass about 1 to 50 M_J have magnetic fields, that they emit extremely intense cyclotron-maser radiation at metric wavelengths, and that this radiation may be detectable with sensitive radio telescopes like the VLA. The radiation is emitted at the electron cyclotron frequency, and has been detected from Earth, Jupiter, Saturn, Uranus and Neptune, from the Sun, from flare stars, and close binaries. The frequency range of cyclotron maser radiation is fixed by the magnetic field strength on the object. To be detected at, say 0.33 GHz, the required field strength is 118 G, which is intermediate between the 14 G field of Jupiter and the ~ 1000 G field of stellar active regions. An estimation of the flux density of the expected radiation can be made from an interpolation between Jupiter's radio emission (10(10) mJy at 5 AU) and that of nearby red dwarf stars ( ~ 100 mJy at 3 pc). Thus the flux from a planet or brown dwarf 3 to 30 times massive than Jupiter is plausibly 1 to 10 mJy, easily detectable with the VLA. If emission is detected, several important parameters about the planet can be deduced: the strength of its magnetic field, the period of its rotation, and the possible existence of a moon such as Jupiter's Io. Possible means of distinguishing stellar maser emissions from those of planets include: 1) Temporal variations and spectra differ from stars to planets. 2) The polarization is likely to be 100% circular or elliptical for planets, but not for stars. We have searched for exoplanet radio emission with 60 hours of observations with the VLA during November 1996. The observed stars with giant planets or brown dwarfs included 51 Peg, 70 Vir, 47 UMa, 55 CnC, Tau Boo, Gl 229, and HD 114762. We will present the method of observation, the limitations due to confusion and background noise, and the results.

  13. The Prospects for Earth-Like Planets within Known Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Gehman, Curtis S.; Adams, Fred C.; Laughlin, Gregory

    1996-11-01

    We consider the possible existence of habitable Earth-like planets in four recently discovered extrasolar planetary systems. Such prospective planets must have orbits that are (1) dynamically stable, and (2) allow for surface temperatures compatible with liquid water. We find that three of the four new systems (51 Peg, rho^1 Cnc, and 47 UMa) are easily capable of supporting habitable planets. The fourth (70 Vir) is capable of having a habitable planet only under rather extreme circumstances. To obtain these results, we develop a probabilistic formulation for the coupled problem of orbital stability and planetary habitability. (SECTION: Extrasolar Planets)

  14. ''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.

  15. Extrasolar Planet in Double Star System Discovered from La Silla

    NASA Astrophysics Data System (ADS)

    1998-11-01

    Early Success With New Swiss Telescope During the past three years, about fifteen planetary companions have been discovered in orbits around dwarf stars. They have revealed to astrophysicists a broad diversity of planetary systems at other stars. Giant planets with masses ranging from half to several times the mass of Jupiter, the largest planet in our own solar system, have been detected with various telescopes. The orbital periods range from 3.1 to 1650 days; while some of the orbits are of circular shape, others are very elongated. The observed diversity naturally raises questions about how these exoplanets are formed. Now, following only a few months of observations, a Swiss team of astronomers [1], working with a new Swiss astronomical facility at the ESO La Silla Observatory mainly dedicated to the search for exoplanets, has made its first planetary detection. It is a massive planet moving in an almost circular orbit around a nearby star that is itself the primary component of a double star system. The Geneva southern extrasolar planet search programme ESO PR Photo 45a/98 ESO PR Photo 45a/98 [Preview - JPEG: 800 x 640 pix - 456k] [High-Res - JPEG: 3000 x 2400 pix - 2.7Mb] ESO PR Photo 45b/98 ESO PR Photo 45b/98 [Preview - JPEG: 800 x 953 pix - 296k] [High-Res - JPEG: 3000 x 3572 pix - 2.3Mb] PR Photo 45a/98 (left) is a view of the dome with the 1.2-m Swiss Leonard Euler Telescope at the ESO La Silla Observatory. The telescope itself is shown in Photo 45b/98 (right). In June 1998, the CORALIE echelle spectrograph was mounted at the 1.2-m Swiss telescope at La Silla and the commissioning phase was begun, during which the telescope and the spectrograph would be trimmed to perfection. This facility is specifically designed for high-precision radial-velocity measurements and it will mostly be used for an ambitious search for large extrasolar planets around stars in the southern celestial hemisphere. Over 1000 stars will be investigated. Such a vast observational

  16. Extrasolar Giant Planet in Earth-like Orbit

    NASA Astrophysics Data System (ADS)

    1999-07-01

    Discovery from a Long-term Project at La Silla A new extrasolar planet has been found at the ESO La Silla Observatory as a companion to iota Horologii (iota Hor) . This 5.4-mag solar-type star is located at a distance of 56 light-years and is just visible to the unaided eye in the southern constellation Horologium (The Pendulum Clock). The discovery is the result of a long-term survey of forty solar-type stars that was begun in November 1992. It is based on highly accurate measurements of stellar radial velocities, i.e. the speed with which a star moves along the line of sight. The presence of a planet in orbit around a star is inferred from observed, regular changes of this velocity, as the host star and its planet revolve around a common center of gravity. Since in all cases the star is much heavier than the planet, the resulting velocity variations of the star are always quite small. The team that found the new planet, now designated iota Hor b , consists of Martin Kürster , Michael Endl and Sebastian Els (ESO-Chile), Artie P. Hatzes and William D. Cochran (University of Texas, Austin, USA), and Stefan Döbereiner and Konrad Dennerl (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany). Iodine cell provides very accurate velocity measurements iota Hor b represents the first discovery of an extrasolar planet with an ESO instrument [1]. The finding is based on data obtained with ESO's highest-resolution spectrograph, the Coudé Echelle Spectrometer (CES) at the 1.4-m Coudé Auxiliary Telescope (CAT). While this telescope has recently been decommissioned, the CES instrument is now coupled via an optical fiber link to the larger ESO 3.6-m telescope, thus permitting the continuation of this survey. The high precision radial velocity measurements that are necessary for a study of this type were achieved by means of a special calibration technique. It incorporates an iodine gas absorption cell and sophisticated data modelling. The cell is used like

  17. 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

  18. Long-term evolution of tidal heating and surface temperature on extrasolar planets

    NASA Astrophysics Data System (ADS)

    Kanova, Michaela; Behounkova, Marie

    2015-04-01

    Increasing number of detected extrasolar planets provides a unique statistical set that may help us to improve our knowledge about planetary evolution. Indirect detection methods employed in search for exoplanets are most sensitive to objects orbiting close to their host star and this criterion gets particularly important in the case of low-mass terrestrial planets. Here, we focus on long-term orbital and thermal evolution of a single planet subjected to stellar tides. Our approach combines evaluation of surface temperature as well as numerical computation of tidal effects on planetary orbit and internal heating. By calculating the tidal evolution of the orbit [1], we analyze the effect of initial orbital parameters (eccentricity, semi-major axis and rotational frequency) on secular changes in surface temperature and tidal dissipation. The maximum surface temperature and temperature gradient is computed during the process and it evolves together with the semi-major axis, the eccentricity and the ratio of spin and orbital frequency. Significant increase in the surface temperature is observed when the planet encounters a spin-orbit resonance. We solve the heat diffusion equation numerically for both 1D and 3D geometry in a thin spherical shell corresponding to a subsurface layer (see e.g. [2]), where the upper boundary condition is given by energy equilibrium and is strongly non-linear in temperature due to Stefan-Boltzmann law. Additionally, we solve the viscoelastic response to the tidal loading during orbital evolution. Following the method of [3,4], the tidal heating is evaluated for Maxwell or Andrade rheology in the time domain. We study disturbing potential caused by the body's deformation, the time dependence of phase lag and time lag during one orbit and compare our results with traditionally used constant tidal lag models (e.g. [1,5]). The effect of a 3D internal structure on the disturbing potential is investigated as well. This study is our first step

  19. A closely packed system of low-mass, low-density planets transiting Kepler-11.

    PubMed

    Lissauer, Jack J; Fabrycky, Daniel C; Ford, Eric B; Borucki, William J; Fressin, Francois; Marcy, Geoffrey W; Orosz, Jerome A; Rowe, Jason F; Torres, Guillermo; Welsh, William F; Batalha, Natalie M; Bryson, Stephen T; Buchhave, Lars A; Caldwell, Douglas A; Carter, Joshua A; Charbonneau, David; Christiansen, Jessie L; Cochran, William D; Desert, Jean-Michel; Dunham, Edward W; Fanelli, Michael N; Fortney, Jonathan J; Gautier, Thomas N; Geary, John C; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer R; Holman, Matthew J; Koch, David G; Latham, David W; Lopez, Eric; McCauliff, Sean; Miller, Neil; Morehead, Robert C; Quintana, Elisa V; Ragozzine, Darin; Sasselov, Dimitar; Short, Donald R; Steffen, Jason H

    2011-02-01

    When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47 days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation. PMID:21293371

  20. 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

  1. Extrasolar Planet in Double Star System Discovered from La Silla

    NASA Astrophysics Data System (ADS)

    1998-11-01

    Early Success With New Swiss Telescope During the past three years, about fifteen planetary companions have been discovered in orbits around dwarf stars. They have revealed to astrophysicists a broad diversity of planetary systems at other stars. Giant planets with masses ranging from half to several times the mass of Jupiter, the largest planet in our own solar system, have been detected with various telescopes. The orbital periods range from 3.1 to 1650 days; while some of the orbits are of circular shape, others are very elongated. The observed diversity naturally raises questions about how these exoplanets are formed. Now, following only a few months of observations, a Swiss team of astronomers [1], working with a new Swiss astronomical facility at the ESO La Silla Observatory mainly dedicated to the search for exoplanets, has made its first planetary detection. It is a massive planet moving in an almost circular orbit around a nearby star that is itself the primary component of a double star system. The Geneva southern extrasolar planet search programme ESO PR Photo 45a/98 ESO PR Photo 45a/98 [Preview - JPEG: 800 x 640 pix - 456k] [High-Res - JPEG: 3000 x 2400 pix - 2.7Mb] ESO PR Photo 45b/98 ESO PR Photo 45b/98 [Preview - JPEG: 800 x 953 pix - 296k] [High-Res - JPEG: 3000 x 3572 pix - 2.3Mb] PR Photo 45a/98 (left) is a view of the dome with the 1.2-m Swiss Leonard Euler Telescope at the ESO La Silla Observatory. The telescope itself is shown in Photo 45b/98 (right). In June 1998, the CORALIE echelle spectrograph was mounted at the 1.2-m Swiss telescope at La Silla and the commissioning phase was begun, during which the telescope and the spectrograph would be trimmed to perfection. This facility is specifically designed for high-precision radial-velocity measurements and it will mostly be used for an ambitious search for large extrasolar planets around stars in the southern celestial hemisphere. Over 1000 stars will be investigated. Such a vast observational

  2. Toward a Model for Detecting Life on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Rye, R.; Storrie-Lombardi, M.

    2001-12-01

    The search for life extraterrestrial life has rapidly expanded during the past several years. In addition to missions to Mars and Europa, NASA now envisions launching an orbiting telescope, Terrestrial Planet Finder (TPF), capable of resolving Earth-sized planets around stars as far away as 50 parsecs within the next 10-15 years. By that time we need to develop our understanding of the effects of life on such planets in order to confidently distinguish inhabited planets from barren ones. Our group is in the process of developing a fully coupled generalized 1-D radiative transfer-atmospheric chemistry model. Around this core we are building the Virtual Planetary Laboratory (VPL) to generate synthetic spectra of hypothetical extrasolar terrestrial planets. Computational modules mimicking the influence of life on atmospheric chemistry/climate are of central importance for analyzing data from TPF and related missions. Here we describe our rationale and initial efforts to parameterize the effects of life using a Virtual Microbial Community (VMC). At first glance, the task of modeling hypothetical inhabited planets appears intractable. However, we may assume that most planets settle into a fairly small number of stable climate/chemistry regimes during their history. These regimes are maintained by negative feedback loops. Transitions from one stable solution to another are singularities, times during which the system is unregulated and may vary wildly. In this context, life is one of several processes modifying the chemical composition of a planetary atmosphere, potentially modifying climate. We seek to elucidate those processes and signatures unique to life and visible from space. The VMC is a first attempt at quantifying the possible range of effects of life on the atmosphere of a planet. We start from the presumption that kinetics and thermodynamics are the same throughout the universe. Given the remarkable metabolic diversity of life on Earth, we assume that all

  3. ORBITAL MIGRATION OF LOW-MASS PLANETS IN EVOLUTIONARY RADIATIVE MODELS: AVOIDING CATASTROPHIC INFALL

    SciTech Connect

    Lyra, Wladimir; Mac Low, Mordecai-Mark; Paardekooper, Sijme-Jan E-mail: mordecai@amnh.or

    2010-06-01

    Outward migration of low-mass planets has recently been shown to be a possibility in non-barotropic disks. We examine the consequences of this result in evolutionary models of protoplanetary disks. Planet migration occurs toward equilibrium radii with zero torque. These radii themselves migrate inwards because of viscous accretion and photoevaporation. We show that as the surface density and temperature fall the planet orbital migration and disk depletion timescales eventually become comparable, with the precise timing depending on the mass of the planet. When this occurs, the planet decouples from the equilibrium radius. At this time, however, the gas surface density is already too low to drive substantial further migration. A higher mass planet, of 10 M {sub +}, can open a gap during the late evolution of the disk, and stops migrating. Low-mass planets, with 1 or 0.1 M {sub +}, released beyond 1 AU in our models avoid migrating into the star. Our results provide support for the reduced migration rates adopted in recent planet population synthesis models.

  4. Astrobiology And Extrasolar Planets- A New Lecture Course At Potsdam University

    NASA Astrophysics Data System (ADS)

    Franck, S. A.; von Bloh, W.; Bounama, Ch.

    2006-08-01

    Astrobiology studies the origin, evolution, distribution, and future of life on Earth and in the Universe. This addresses a very wide range of questions that have been asked by mankind from the beginning. On the other hand, the discovery of the first extrasolar planet orbiting a Sun-like star by Mayor and Queloz in 1995 opened a new area for astrobiological research. Although most of the newly discovered extrasolar planets are giants with no underlying solid surfaces or oceans that could support a biosphere, the distribution of masses lets scientists suppose that there must be a multitude of planets with lower masses, including Earth-mass planets. The lecture course contains the following topics: Survey about Extrasolar Planets, Detection Methods, Simple Earth System Models, Dynamical Earth System Models, Habitable Zones, Dynamical Habitability, Rare Earth Hypothesis, Drake Formula, Panspermia, Origin of Life, Cambrian Explosion, Impacts and Climate, Long-Term Future Scenarios, Future Space Missions.

  5. FIB machining of occulting masks for imaging of extrasolar planets

    NASA Astrophysics Data System (ADS)

    Raja, Shilpa N.; Aziz, Michael J.; Foley, James W.; Tolls, Volker

    2009-08-01

    We are developing the ability for Focused Ion Beam (FIB) machining of occulting masks for use in coronagraphs. These masks will be used as soft-edged Lyot stops to suppress light from stars and allow direct imaging of extrasolar planets. The FIB approach is attractive because it has the potential for higher precision than mechanical machining and for larger volumes than electron-beam lithography. The mask fabrication process is trifold: 1) a transparent material-currently, poly(methyl methacrylate) (PMMA)-is doped with dyes; 2) the mask shape is FIB milled into the material; and 3) the mask is coated with another layer of index-matching transparent absorber. Using a Zeiss NVision 40 FIB system, we have fabricated conical-shaped masks of various slopes in dye-doped PMMA. Inherent in this process is the advantage of control of the features through programming the ion beam track. We have also optically characterized these masks as well as the dye-doped absorbing material. We have found that the dye-doped PMMA has a very high absorbance, >1 OD.

  6. Evolutionary Models of Extrasolar Giant Planets and Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Burrows, A.; Hubbard, B.; Lunine, J.; Guillot, T.; Saumon, D.; Freedman, R.

    1996-09-01

    With the discovery of the companions of 51 Peg, 55 Cnc, tau Boo, upsilon And, 70 Vir, 47 UMa, and Gl229, evolutionary and spectral models of gas giants and/or brown dwarfs with masses from 0.3 through 60 times that of Jupiter assume a new and central role in the emerging field of extrasolar planetary studies. In this contribution, we describe the structural, atmospheric, and evolutionary characteristics of such exotic objects, as determined by our recent theoretical calculations (Burrows et al. 1995; Guillot et al. 1996; Saumon et al. 1996; Marley et al. 1996). The issue, in part diversionary, of what distinguishes a brown dwarf from a giant planet will be addressed, as will the luminosities, effective temperatures, gravities, colors, and spectral signatures of these beasts as a function of age and mass. Our theoretical calculations can be used to establish direct search strategies via SIRTF, ISO, and HST (NICMOS), and via various ground--based adaptive optics and interferometric platforms planned for the near future.

  7. 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.

  8. Terrestrial Planet Formation around Low-Mass Stars: Effect of the Mass of Central Stars

    NASA Astrophysics Data System (ADS)

    Oshino, Shoichi; Matsumoto, Yuji; Kokubo, Eiichiro

    2015-12-01

    The Kepler space telescope has detected several thousand planets and candidates.Their central stars are mainly FGK-type stars.It is difficult to observe M-stars by using visible light since M-stars have their peak radiation in the infrared region.However, recently there are several survey projects for planets around M-stars such as the InfraRed Doppler (IRD) survey of the Subaru telescope.Therefore it is expected that the number of planets around M-stars will increase in the near future.The habitable zone of M-stars is closer to the stars than that of G-stars.For this reason, the possibility of finding habitable planets is expected to be higher.Here we study the formation of close-in terrestrial planets by giant impacts of protoplanets around low-mass stars by using N-body simulations.An important parameter that controls formation processes is the ratio between the physical radius of a planet and its Hill radius, which decreases with the stellar mass.We systematically change the mass of the central stars and investigate its effects on terrestrial planet formation.We find that the mass of the maximum planet decreases with the mass of central stars, while the number of planets in the system increases.We also find that the orbital separation of adjacent planets normalized by their Hill radius increases with the stellar mass.

  9. 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.

  10. Extrasolar Planet Transits Observed at Kitt Peak National Observatory

    NASA Technical Reports Server (NTRS)

    Sada, Pedro V.; Jennings, Donald E.; Deming, Drake; Jennings, Donald E.; Jackson, Brian; Hamilton, Catrina M.; Fraine, Jonathan; Peterson, Steven W.; Haase, Flynn; Bays, Kevin; Lunsford, Allen; O'Gorman, Eamon

    2012-01-01

    We obtained J-, H-, and JH-band photometry of known extrasolar planet transiting systems at the 2.1 m Kitt Peak National Observatory Telescope using the FLAMINGOS infrared camera between 2008 October and 2011 October. From the derived light curves we have extracted the midtransit times, transit depths and transit durations for these events. The precise midtransit times obtained help improve the orbital periods and also constrain transit-time variations of the systems. For most cases the published system parameters successfully accounted for our observed light curves, but in some instances we derive improved planetary radii and orbital periods. We complemented our 2.1 m infrared observations using CCD z0-band and B-band photometry (plus two H(alpha) filter observations) obtained with the Kitt Peak Visitor Center Telescope, and with four H-band transits observed in 2007 October with the NSO's 1.6 m McMath-Pierce Solar Telescope. The principal highlights of our results are (1) Our ensemble of J-band planetary radii agree with optical radii, with the best-fit relation being RpRJ0:0017 0:979RpRvis. (2) We observe starspot crossings during the transit of WASP-11HAT-P-10. (3) We detect starspot crossings by HAT-P-11b (Kepler-3b), thus confirming that the magnetic evolution of the stellar active regions can be monitored even after the Kepler mission has ended. (4) We confirm a grazing transit for HAT-P-27WASP-40. In total, we present 57 individual transits of 32 known exoplanet systems.

  11. A Thermospheric Circulation Model for Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Koskinen, T. T.; Aylward, A. D.; Smith, C. G. A.; Miller, S.

    2007-05-01

    Several models of extrasolar giant planet (EGP) atmospheres have been developed recently. Many of them are one-dimensional or concentrate on the lower or middle atmosphere. Three-dimensional hydrodynamic models are needed to study the horizontal variations in temperature and composition of EGP atmospheres. Circulation models for the upper atmosphere are particularly important as they can be used to study the thermal structure due to stellar irradiation, radiative cooling, and atmospheric circulation in the thermospheres of close-in EGPs and hence the rate of evaporation of their atmospheres. We present a generic gas giant model that is capable of generating three-dimensional, self-consistent global simulations of stable EGP thermospheres at different orbital distances. Calculations performed by this model indicate that IR emissions from H+3 ions may play a significant role in cooling the thermospheres of EGPs at least in the range of 0.2-1 AU from a solar-type host star. In this range thermal dissociation of H2 is negligible and ion densities are small compared to the overall neutral density. Inside 0.2 AU thermal dissociation and dissociative photoionization of H2 may prevent the effective formation of H+3. In the absence of radiative cooling from H+3 the upper atmospheres reach temperatures well above 10,000 K within ~0.5 AU. In this case the upper thermospheres are entirely converted into atomic hydrogen and the temperatures are high enough for significant atmospheric loss to take place. Our model is capable of calculating the IR signal strengths for various vibrational transitions of H+3 based on the thermal state and the composition of the atmosphere. Potential detection of such signals would thus provide a validation of some of our results.

  12. Limits on Line Bisector Variability for Stars with Extrasolar Planets

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  13. Views from EPOXI: Colors in Our Solar System as an Analog for Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Crow, Carolyn A.; McFadden, L. A.; Robinson, T.; Meadows, V. S.; Livengood, T. A.; Hewagama, T.; Barry, R. K.; Deming, L. D.; Lisse, C. M.; Wellnitz, Dennis

    2011-01-01

    The first visible-light studies of Earth-sized extrasolar planets will employ photometry or low-resolution spectroscopy. This work uses EPOCh medium-hand filter photometry between 150 and 950 nm obtained with the Deep Impact (DI) High Resolution Instrument (HRI) of Earth, the Moon, and Mars in addition to previous full-disk observations of the other six solar system planets and Titan to analyze the limitations of using photometric colors to characterize extrasolar planets. We determined that the HRI 350, 550, and 850 nm filters are optimal for distinguishing Earth from the other planets and separating planets to first order based on their atmospheric and surface properties. Detailed conclusions that can be drawn about exoplanet atmospheres simply from a color-color plot are limited due to potentially competing physical processes in the atmosphere. The presence of a Rayleigh scattering atmosphere can be detected by an increase in the 350-550 nm brightness ratio, but the absence of Rayleigh scattering cannot be confirmed due to the existence of atmospheric and surface absorbing species in the UV. Methane and ammonia are the only species responsible for strong absorption in the 850 nm filter in our solar system. The combination of physical processes present on extrasolar planets may differ from those we see locally. Nevertheless, a generation of telescopes capable of collecting such photometric observations can serve a critical role in first-order characterization and constraining the population of Earth-like extrasolar planets.

  14. Diversity of extrasolar planets and diversity of molecular cloud cores. I. Semimajor axes

    SciTech Connect

    Jin, Liping; Li, Min E-mail: minli09@mails.jlu.edu.cn

    2014-03-01

    We show that the diversity of extrasolar planetary systems may be related to the diversity of molecular cloud cores. In previous studies of planet formation, artificial initial conditions of protoplanetary disks or steady state disks, such as the minimum mass nebula model, have often been used so that the influence of cloud core properties on planet formation is not realized. To specifically and quantitatively demonstrate our point, we calculate the dependence of disk properties on cloud core properties and show that the boundary of the giant planet formation region in a disk is a function of cloud core properties with the conventional core accretion model of giant planet formation. The gravitational stability of a disk depends on the properties of its progenitor cloud core. We also compare our calculations with observations of extrasolar planets. From the observational data of cloud cores, our model could infer the range and most frequent values of observed semimajor axes of extrasolar planets. Our calculations suggest that planet formation at the snowline alone could not completely explain the semimajor axis distribution. If the current observations are not biased, our calculations indicate that the planet formation at the snowline is inefficient. We suggest that there will be more observed planets with semimajor axis <9 AU than >9 AU, even with a longer duration of observations, if the planet formation at the snowline is inefficient.

  15. GAP OPENING BY EXTREMELY LOW-MASS PLANETS IN A VISCOUS DISK

    SciTech Connect

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2013-05-20

    By numerically integrating the compressible Navier-Stokes equations in two dimensions, we calculate the criterion for gap formation by a very low mass (q {approx} 10{sup -4}) protoplanet on a fixed orbit in a thin viscous disk. In contrast with some previously proposed gap-opening criteria, we find that a planet can open a gap even if the Hill radius is smaller than the disk scale height. Moreover, in the low-viscosity limit, we find no minimum mass necessary to open a gap for a planet held on a fixed orbit. In particular, a Neptune-mass planet will open a gap in a minimum mass solar nebula with suitably low viscosity ({alpha} {approx}< 10{sup -4}). We find that the mass threshold scales as the square root of viscosity in the low mass regime. This is because the gap width for critical planet masses in this regime is a fixed multiple of the scale height, not of the Hill radius of the planet.

  16. Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

    SciTech Connect

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

    2014-08-01

    We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajor axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.

  17. Observational Constraints on Low-Mass Stellar Evolution and Planet Formation

    NASA Astrophysics Data System (ADS)

    Birkby, Jayne Louise

    2011-07-01

    Low-mass stars (? < 1.0M⊙) account for more than 70% of the galactic stellar population yet models describing the evolution of their fundamental properties lack stringent observational constraints, especially at early ages. Furthermore, recent observations indicate a significant discrepancy between model predictions and the precise (2 - 3%) observed, dynamical masses and radii measured using low-mass eclipsing binary systems (EBs). Additionally, the theory of planet formation via core accretion predicts notably less hot-Jupiter formation around M-dwarfs (Mdot ? ≤ 0.6M⊙), but as yet, no large enough study exists to robustly test it. Further still, it is predicted that the dynamic environment of stellar clusters, in which most stars are believed to form, hampers planet formation, but again, current null detections of planets in stellar clusters are not statistically significant to test the theory. More observations are required to cement both the theory of low-mass stellar evolution and planet formation. This thesis aims to provide the necessary constraints by uncovering new low-mass EBs and transiting exoplanets in time-series photometry and follow-up spectroscopy from the Monitor project, a photometric monitoring campaign of low-mass stars in nine young open clusters, and in the WFCAM Transit Survey (WTS), a photometric monitoring campaign of ∼10,000 field M-dwarfs. Chapters 3 and 4 present my study of the young (130 Myr) cluster, M 50. I confirm three EB candidates as cluster members, including evidence that one of these is in a triple system with a wide-separation, low-mass tertiary component. The derived masses and radii for this system and one further double-lined, non-cluster member are presented, but these objects required dedicated, single-slit spectroscopic follow-up to yield the accuracy required to test pre-main sequence models. My non-detection of planets in this cluster is consistent with the results of all other cluster transit surveys. The

  18. Habitability in The Solar System and on Extrasolar Planets and Moons

    NASA Astrophysics Data System (ADS)

    McKay, C. P.

    2015-12-01

    The criteria for a habitable world initially was based on Earth and centered around liquid water on the surface, warmed by a Sun-like star. The moons of the outer Solar System, principally Europa and Enceladus, have demonstrated that liquid water can exist below the surface warmed by tidal forces from a giant planet. Titan demonstrates that surface liquids other than water - liquid methane/ethane - may be common on other worlds. Considering the numerous extrasolar planets so far discovered and the prospect of discovering extrasolar moons it is timely to reconsider the possibilities for habitable environments in the Solar System and on extrasolar planets and moons and enumerate the attributes and search methods for detecting habitable worlds and evidence of life.

  19. Habitability in the Solar System and on Extrasolar Planets and Moons

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.

    2015-01-01

    The criteria for a habitable world initially was based on Earth and centered around liquid water on the surface, warmed by a Sun-like star. The moons of the outer Solar System, principally Europa and Enceladus, have demonstrated that liquid water can exist below the surface warmed by tidal forces from a giant planet. Titan demonstrates that surface liquids other than water - liquid methane/ethane - may be common on other worlds. Considering the numerous extrasolar planets so far discovered and the prospect of discovering extrasolar moons it is timely to reconsider the possibilities for habitability in the Solar System and on extrasolar planets and moons and enumerate the attributes and search methods for detecting habitable worlds and evidence of life.

  20. 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

  1. WARM SATURNS: ON THE NATURE OF RINGS AROUND EXTRASOLAR PLANETS THAT RESIDE INSIDE THE ICE LINE

    SciTech Connect

    Schlichting, Hilke E.; Chang, Philip E-mail: pchang@cita.utoronto.ca

    2011-06-20

    We discuss the nature of rings that may exist around extrasolar planets. Taking the general properties of rings around the gas giants in the solar system, we infer the likely properties of rings around exoplanets that reside inside the ice line. Due to their proximity to their host star, rings around such exoplanets must primarily consist of rocky materials. However, we find that despite the higher densities of rock compared to ice, most of the observed extrasolar planets with reliable radius measurements have sufficiently large Roche radii to support rings. For the currently known transiting extrasolar planets, Poynting-Robertson drag is not effective in significantly altering the dynamics of individual ring particles over a time span of 10{sup 8} yr provided that they exceed about 1 m in size. In addition, we show that significantly smaller ring particles can exist in optically thick rings, for which we find typical ring lifetimes ranging from a few times 10{sup 6} to a few times 10{sup 9} yr. Most interestingly, we find that many of the rings could have nontrivial Laplacian planes due to the increased effects of the orbital quadrupole caused by the exoplanets' proximity to their host star, allowing a constraint on the J{sub 2} of extrasolar planets from ring observations. This is particularly exciting, since a planet's J{sub 2} reveals information about its interior structure. Furthermore, measurements of an exoplanet's J{sub 2} from warped rings and of its oblateness would together place limits on its spin period. Based on the constraints that we have derived for extrasolar rings, we anticipate that the best candidates for ring detections will come from transit observations by the Kepler spacecraft of extrasolar planets with semimajor axes {approx}0.1 AU and larger.

  2. Direct imaging search for planets around low-mass stars and spectroscopic characterization of young exoplanets

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan Peter

    Low--mass stars between 0.1--0.6 M⊙ are the most abundant members our galaxy and may be the most common sites of planet formation, but little is known about the outer architecture of their planetary systems. We have carried out a high-contrast adaptive imaging search for gas giant planets between 1--13 MJup around 122 newly identified young M dwarfs in the solar neighborhood ( ≲ 35 pc). Half of our targets are younger than 145 Myr, and 90% are younger than 580 Myr. After removing 39 resolved stellar binaries, our homogeneous sample of 83 single young M dwarfs makes it the largest imaging search for planets around low--mass stars to date. Our H- and K- band coronagraphic observations with Subaru/HiCIAO and Keck/NIRC2 achieve typical contrasts of 9--13 mag and 12--14 mag at 100, respectively, which corresponds to limiting masses of ˜1--10 M Jup at 10--30 AU for most of our sample. We discovered four brown dwarfs with masses between 25--60 MJup at projected separations of 4--190 AU. Over 100 candidate planets were discovered, nearly all of which were found to be background stars from follow-up second epoch imaging. Our null detection of planets nevertheless provides strong statistical constraints on the occurrence rate of giant planets around M dwarfs. Assuming circular orbits and a logarithmically-flat power law distribution in planet mass and semi--major axis of the form d 2N=(dloga dlogm) infinity m0 a0, we measure an upper limit (at the 95% confidence level) of 8.8% and 12.6% for 1--13 MJup companions between 10--100 AU for hot start and cold start evolutionary models, respectively. For massive gas giant planets in the 5--13 M Jup range like those orbiting HR 8799, GJ 504, and beta Pictoris, we find that fewer than 5.3% (7.8%) of M dwarfs harbor these planets between 10--100 AU for a hot start (cold start) formation scenario. Our best constraints are for brown dwarf companions; the frequency of 13--75 MJup companions between (de--projected) physical

  3. The Blue Dot Workshop: Spectroscopic Search for Life on Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Des Marais, David J. (Editor)

    1997-01-01

    This workshop explored the key questions and challenges associated with detecting life on an extrasolar planet. The final product will be a NASA Conference Publication which includes the abstracts from 21 talks, summaries of key findings, and recommendations for future research. The workshop included sessions on three related topics: the biogeochemistry of biogenic gases in the atmosphere, the chemistry and spectroscopy of planetary atmospheres, and the remote sensing of planetary atmospheres and surfaces. With the observation that planetary formation is probably a common phenomenon, together with the advent of the technical capability to locate and describe extrasolar planets, this research area indeed has an exciting future.

  4. Limits on the Magnetosphere/Stellar Wind Interactions for the Extrasolar Planet about Tau Bootis

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Desch, M. D.; Lazio, T. J.; Bastian, T.; Zarka, P.

    Among the most impressive astronomical discoveries in the past decade are the observations of Jupiter-like planets in orbit around stars similar to our sun (Mayor and Queloz 1995; Marcy 1998). These extrasolar planets are detected primarily from optical signatures of the star's orbital perturbation about the star/planet center of mass. To date, over 80 massive planets have been discovered about sun-like stars, these stars located in the near-vicinity of our own solar system (< 100 pc). By analogy with the sun's gas giant planets, it has been predicted that these extrasolar planets will have electrically-active stellar-wind driven planetary magnetospheres possibly capable of emitting long-wavelength radio emission (Burke 1992; Farrell et al. 1999; Bastian et al. 2000; Zarka et al. 2001) consistent with radiometric Bode's laws known to apply in our solar system. In 1999 and in 2002, the Very Large Array (VLA) surveyed the region near Tau Bootes for long-wavelength radio emission from its extrasolar planet. This planet had been previously predicted to be a good candidate for coherent electron cyclotron radio emission in the 10's of MHz. While no obvious signal was detected at 74 MHz to a sensitivity of <0.12 Janskys, the results can be applied to place upper limits on the stellar winds and planetary magnetic field.

  5. TIDAL EVOLUTION OF CLOSE-IN EXTRASOLAR PLANETS: HIGH STELLAR Q FROM NEW THEORETICAL MODELS

    SciTech Connect

    Penev, Kaloyan; Sasselov, Dimitar

    2011-04-10

    In recent years it has been shown that the tidal coupling between extrasolar planets and their stars could be an important mechanism leading to orbital evolution. Both the tides the planet raises on the star and vice versa are important and dissipation efficiencies ranging over four orders of magnitude are being used. In addition, the discovery of extrasolar planets extremely close to their stars has made it clear that the estimates of the tidal quality factor, Q, of the stars based on Jupiter and its satellite system and on main-sequence binary star observations are too low, resulting in lifetimes for the closest planets orders of magnitude smaller than their age. We argue that those estimates of the tidal dissipation efficiency are not applicable for stars with spin periods much longer than the extrasolar planets' orbital period. We address the problem by applying our own values for the dissipation efficiency of tides, based on our numerical simulations of externally perturbed volumes of stellar-like convection. The range of dissipation we find for main-sequence stars corresponds to stellar Q{sub *} of 10{sup 8} to 3 x 10{sup 9}. The derived orbit lifetimes are comparable to or much longer than the ages of the observed extrasolar planetary systems. The predicted orbital decay transit timing variations due to the tidal coupling are below the rate of ms yr{sup -1} for currently known systems, but within reach of an extended Kepler mission provided such objects are found in its field.

  6. 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.

  7. 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

  8. The High-Energy Radiation Environment of Planets around Low-Mass Stars

    NASA Astrophysics Data System (ADS)

    Shkolnik, Evgenya; Miles, Brittany; Barman, Travis; Peacock, Sarah

    2015-12-01

    Low-mass stars are the dominant planet hosts averaging about one planet per star. Many of these planets orbit in the canonical habitable zone (HZ) of the star where, if other conditions allowed, liquid water may exist on the surface.A planet’s habitability, including atmospheric retention, is strongly dependent on the star’s ultraviolet (UV) emission, which chemically modifies, ionizes, and even erodes the atmosphere over time including the photodissociation of important diagnostic molecules, e.g. H2O, CH4, and CO2. The UV spectral slope of a low-mass star can enhance atmospheric lifetimes, and increase the detectability of biologically generated gases. But, a different slope may lead to the formation of abiotic oxygen and ozone producing a false-positive biosignature for oxygenic photosynthesis. Realistic constraints on the incident UV flux over a planet’s lifetime are necessary to explore the cumulative effects on the evolution, composition, and fate of a HZ planetary atmosphere.NASA’s Galaxy Evolution Explorer (GALEX) provides a unique data set with which to study the broadband UV emission from many hundreds of M dwarfs. The GALEX satellite has imaged nearly 3/4 of the sky simultaneously in two UV bands: near-UV (NUV; 175-275 nm) and far-UV (FUV; 135-175 nm). With these data these, we are able to calculate the mean UV emission and its level of variability at these wavelengths over critical planet formation and evolution time scales to better understand the probable conditions in HZ planetary atmospheres.In the near future, dedicated CubeSats (miniaturized satellites for space research) to monitor M dwarf hosts of transiting exoplanets will provide the best opportunity to measure their UV variability, constrain the probabilities of detecting habitable (and inhabited) planets, and provide the correct context within which to interpret IR transmission and emission spectroscopy of transiting exoplanets.

  9. Characterizing transiting extrasolar giant planets: On companions, rings, and love handles

    NASA Astrophysics Data System (ADS)

    Barnes, Jason Wayne

    2004-10-01

    For my Ph.D. research I investigated the prospects for characterizing transiting extrasolar giant planets from their transit lightcurves. Hubble Space Telescope photometry of transiting planet HD209458b revealed that the planet has no moons. Here, I show that tidal orbital evolution of moons limits their lifetimes, and hence that no moons larger than Amalthea in size should survive around HD209458b, consistent with observations. I then calculate the detectability and scientific potential of planetary rings and oblateness. Oblateness will prove difficult to reliably detect, even with the Hubble Space Telescope. However, large Saturn-like ring systems should be easy to find around transiting extrasolar giant planets if such rings exist.

  10. A Program To Detect and Characterize Extra-Solar Giant Planets

    NASA Technical Reports Server (NTRS)

    Noyes, Robert W.; Boyce, Joseph M. (Technical Monitor)

    2001-01-01

    This grant report highlights activity in the following areas: (1) Improvement in Precise Radial Velocity (PRV) analysis code; (2) Reanalysis of previous data; (3) Improvements to the AFOE (Advanced Fiber Optic Echelle) spectrograph; (4) Development of PRV capabilities for the Hectochelle; (5) Extra-solar planet studies; (6) Longer-term plans for the AFOE; (7) Completion and publication of the analysis of the transiting gas-giant planet HD 209458b.

  11. Transit Timing Observations of the Extrasolar Hot-Neptune Planet GL 436 b

    NASA Astrophysics Data System (ADS)

    Stringfellow, Guy S.; Coughlin, Jeffrey L.; López-Morales, Mercedes; Becker, Andrew C.; Krajci, Tom; Mezzalira, Fabio; Agol, Eric

    2009-02-01

    Gliese 436 is an M dwarf with a mass of 0.45 Msolar and hosts the extrasolar planet GL 436 b [3, 6, 7, 2], which is currently the least massive transiting planet with a mass of ~23.17 M⊕ [10], and the only planet known to transit an M dwarf. GL 436 b represents the first transiting detection of the class of extrasolar planets known as ``Hot Neptunes'' that have masses within a few times that of Neptune's mass (~17 M⊕) and orbital semimajor axis <0.1 AU about the host star. Unlike most other known transiting extrasolar planets, GL 436 b has a high eccentricity (e~0.16). This brings to light a new parameter space for habitability zones of extrasolar planets with host star masses much smaller than typical stars of roughly a solar mass. This unique system is an ideal candidate for orbital perturbation and transit-time variation (TTV) studies to detect smaller, possibly Earth-mass planets in the system. In April 2008 we began a long-term intensive campaign to obtain complete high-precision light curves using the Apache Point Observatory's 3.5-meter telescope, NMSU's 1-meter telescope (located at APO), and Sommers Bausch Observatory's 24'' telescope. These light curves are being analyzed together, along with amateur and other professional astronomer observations. Results of our analysis are discussed. Continued measurements over the next few years are needed to determine if additional planets reside in the system, and to study the impact of other manifestations on the light curves, such as star spots and active regions.

  12. Planetary Formation: From The Earth And Moon To Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of planetary growth, emphasizing the formation of habitable planets, is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost - to orbital decay within the protoplanetary disk. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. Specific issues to be discussed include: (1) how do giant planets influence the formation and habitability of terrestrial planets? (2) could a giant impact leading to lunar formation have occurred - 100 million years after the condensation of the oldest meteorites?

  13. Detection and Properties of Extrasolar Planets in Double and Multiple Star Systems

    NASA Astrophysics Data System (ADS)

    Eggenberger, A.; Udry, S.; Mayor, M.; Beuzit, J.-L.; Lagrange, A. M.; Chauvin, G.

    2004-12-01

    Among the extrasolar planets known today, 19 are orbiting a component of a multiple star system. In this contribution, we show that the properties of planets found in multiple star systems seem to be different from the ones of planets orbiting isolated stars: (i) as pointed out by Zucker & Mazeh (2002), the most massive short-period planets are all found in binaries; (ii) planets orbiting a component of a multiple star system tend to have a very low eccentricity when their period is shorter than about 40 days. These observations suggest that some kind of migration has been present in the history of the short-period planets found in multiple star systems, but are not easily explained by the current models of planet formation and evolution. Our knowledge regarding the existence and the characteristics of extrasolar planets in multiple star systems is, however, far from being complete. In particular, the influence of stellar duplicity on planet formation and evolution is still to be quantified. This is the goal of our VLT/NACO adaptive optics survey, which is also discussed here.

  14. Predicting and Disentangling Stellar Variability in Quiet Stars: Implications for Low-mass Planet Confirmation

    NASA Astrophysics Data System (ADS)

    Cegla, Heather; Watson, Chris; Stassun, Keivan; Shelyag, Sergiy; Mathioudakis, Mihalis; Bastien, Fabienne; Pepper, Josh

    2015-08-01

    Stellar variability is one of the main limiting factors in the detection and confirmation of low-mass planets. Even for magnetically quiet stars, astrophysical noise could be present at the 10m/s level. For these stars we demonstrate, using Kepler and GALEX data, that it may be possible to use photometric variability to predict the RV noise. Such a relationship creates a filtering mechanism to prioritize planetary candidates in transit surveys that are ideal for RV follow-up. Going beyond this, we use 3D magnetohydrodynamical (MHD) simulations to create Sun-as-a-star observations, focusing on stellar surface magneto-convection. Using these model observations we have identified correlations between the stellar line shape, brightness, and RV variability. We demonstrate that photometric observations may be key in disentangling stellar and planetary induced RV signals. Disentangling these signals allows us to reach the 10 cm/s noise level in our model star, indicating significant promise for the confirmation of low-mass planet candidates in the future.

  15. GRAVITY WAVES ON HOT EXTRASOLAR PLANETS. I. PROPAGATION AND INTERACTION WITH THE BACKGROUND

    SciTech Connect

    Watkins, Chris; Cho, J. Y-K. E-mail: J.Cho@qmul.ac.u

    2010-05-01

    We study the effects of gravity waves, or g-modes, on hot extrasolar planets. These planets are expected to possess stably stratified atmospheres, which support gravity waves. In this paper, we review the derivation of the equation that governs the linear dynamics of gravity waves and describe its application to a hot extrasolar planet, using HD 209458 b as a generic example. We find that gravity waves can exhibit a wide range of behaviors, even for a single atmospheric profile. The waves can significantly accelerate or decelerate the background mean flow, depending on the difference between the wave phase and mean flow speeds. In addition, the waves can provide significant heating ({approx}10{sup 2} to {approx}10{sup 3} K per planetary rotation), especially to the region of the atmosphere above about 10 scale heights from the excitation region. Furthermore, by propagating horizontally, gravity waves provide a mechanism for transporting momentum and heat from the dayside of a tidally locked planet to its nightside. We discuss work that needs to be undertaken to incorporate these effects in current atmosphere models of extrasolar planets.

  16. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. I. THE ROLE OF ELECTRON AVALANCHE

    SciTech Connect

    Helling, Ch.; Jardine, M.; Witte, S.; Diver, D. A.

    2011-01-20

    Brown dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short timescales, inconsistent with the observation of stochastic ionization events of the solar system planets. We argue that a significant volume of the clouds in brown dwarfs and extrasolar planets is susceptible to local discharge events. These are electron avalanches triggered by charged dust grains. Such intra-cloud discharges occur on timescales shorter than the time needed to neutralize the dust grains by collisional processes. An ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large-scale magnetic field.

  17. 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.

  18. 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.

  19. Extrasolar Planets: Towards Comparative Planetology beyond the Solar System

    NASA Astrophysics Data System (ADS)

    Khan, A. H.

    2012-09-01

    Today Scenario planet logy is a very important concept because now days the scientific research finding new and new planets and our work's range becoming too long. In the previous study shows about 10-12 years the research of planet logy now has changed . Few years ago we was talking about Sun planet, Earth planet , Moon ,Mars Jupiter & Venus etc. included but now the time has totally changed the recent studies showed that mono lakes California find the arsenic food use by micro organism that show that our study is very tiny as compare to planet long areas .We have very well known that arsenic is the toxic agent's and the toxic agent's present in the lakes and micro organism developing and life going on it's a unbelievable point for us but nature always play a magical games. In few years ago Aliens was the story no one believe the Aliens origin but now the aliens showed catch by our space craft and shuttle and every one believe that Aliens origin but at the moment's I would like to mention one point's that we have too more work required because our planet logy has a vast field. Most of the time our scientific mission shows that this planet found liquid oxygen ,this planet found hydrogen .I would like to clear that point's that all planet logy depend in to the chemical and these chemical gave the indication of the life but we are not abele to developed the adaptation according to the micro organism . Planet logy compare before study shows that Sun it's a combination of the various gases combination surrounded in a round form and now the central Sun Planets ,moons ,comets and asteroids In other word we can say that Or Sun has a wide range of the physical and Chemical properties in the after the development we can say that all chemical and physical property engaged with a certain environment and form a various contains like asteroids, moon, Comets etc. Few studies shows that other planet life affected to the out living planet .We can assure with the example the life

  20. The Average Density of Extrasolar Habitable Planets Over Cosmological Time Scales

    NASA Astrophysics Data System (ADS)

    von Bloh, W.; Franck, S.; Bounama, C.; Schellnhuber, H. J.

    A general modelling scheme for assessing the suitability for life on any Earth-like ex- trasolar planet is presented. This approach is based on an integrated Earth system anal- ysis in order to calculate the habitable zone in main-sequence-star planetary systems. Within this model the evolution of the habitable zone over geological time scales is straightforward to calculate and allows an estimate of the probability that an Earth-like planet is within the habitable zone of an extrasolar planetary system. The probability depends explicitly on the time since planet formation. A new attempt by Lineweaver (2001) to estimate the formation rate of Earth-like planets over cosmological time scales is applied to calculate the average density of habitable planets as a function of time. This approach is based on a quantitative determination of metallicity from star formation rates as an ingredient for forming Earth-like planets. Combining this result with our estimations of extrasolar habitable zones yields the average density of habit- able planets over cosmological time scales. We find that there was a maximum density of habitable planets at the time of Earth's origin.

  1. 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

  2. A Framework for Characterizing the Atmospheres of Low-mass Low-density Transiting Planets

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Mordasini, Christoph; Nettelmann, Nadine; Kempton, Eliza M.-R.; Greene, Thomas P.; Zahnle, Kevin

    2013-09-01

    We perform modeling investigations to aid in understanding the atmospheres and composition of small planets of ~2-4 Earth radii, which are now known to be common in our Galaxy. GJ 1214b is a well-studied example whose atmospheric transmission spectrum has been observed by many investigators. Here we take a step back from GJ 1214b to investigate the role that planetary mass, composition, and temperature play in impacting the transmission spectra of these low-mass low-density (LMLD) planets. Under the assumption that these planets accrete modest hydrogen-dominated atmospheres and planetesimals, we use population synthesis models to show that predicted metal enrichments of the H/He envelope are high, with metal mass fraction Z env values commonly 0.6-0.9, or ~100-400+ times solar. The high mean molecular weight of such atmospheres (μ ≈ 5-12) would naturally help to flatten the transmission spectrum of most LMLD planets. The high metal abundance would also provide significant condensible material for cloud formation. It is known that the H/He abundance in Uranus and Neptune decreases with depth, and we show that atmospheric evaporation of LMLD planets could expose atmospheric layers with gradually higher Z env. However, values of Z env close to solar composition can also arise, so diversity should be expected. Photochemically produced hazes, potentially due to methane photolysis, are another possibility for obscuring transmission spectra. Such hazes may not form above T eq of ~800-1100 K, which is testable if such warm, otherwise low mean molecular weight atmospheres are stable against atmospheric evaporation. We find that available transmission data are consistent with relatively high mean molecular weight atmospheres for GJ 1214b and "warm Neptune" GJ 436b. We examine future prospects for characterizing GJ 1214b with Hubble and the James Webb Space Telescope.

  3. A FRAMEWORK FOR CHARACTERIZING THE ATMOSPHERES OF LOW-MASS LOW-DENSITY TRANSITING PLANETS

    SciTech Connect

    Fortney, Jonathan J.; Nettelmann, Nadine; Mordasini, Christoph; Kempton, Eliza M.-R.; Greene, Thomas P.; Zahnle, Kevin

    2013-09-20

    We perform modeling investigations to aid in understanding the atmospheres and composition of small planets of ∼2-4 Earth radii, which are now known to be common in our Galaxy. GJ 1214b is a well-studied example whose atmospheric transmission spectrum has been observed by many investigators. Here we take a step back from GJ 1214b to investigate the role that planetary mass, composition, and temperature play in impacting the transmission spectra of these low-mass low-density (LMLD) planets. Under the assumption that these planets accrete modest hydrogen-dominated atmospheres and planetesimals, we use population synthesis models to show that predicted metal enrichments of the H/He envelope are high, with metal mass fraction Z{sub env} values commonly 0.6-0.9, or ∼100-400+ times solar. The high mean molecular weight of such atmospheres (μ ≈ 5-12) would naturally help to flatten the transmission spectrum of most LMLD planets. The high metal abundance would also provide significant condensible material for cloud formation. It is known that the H/He abundance in Uranus and Neptune decreases with depth, and we show that atmospheric evaporation of LMLD planets could expose atmospheric layers with gradually higher Z{sub env}. However, values of Z{sub env} close to solar composition can also arise, so diversity should be expected. Photochemically produced hazes, potentially due to methane photolysis, are another possibility for obscuring transmission spectra. Such hazes may not form above T{sub eq} of ∼800-1100 K, which is testable if such warm, otherwise low mean molecular weight atmospheres are stable against atmospheric evaporation. We find that available transmission data are consistent with relatively high mean molecular weight atmospheres for GJ 1214b and 'warm Neptune' GJ 436b. We examine future prospects for characterizing GJ 1214b with Hubble and the James Webb Space Telescope.

  4. 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.

  5. Drag-o-llision Models of Extrasolar Planets in Debris Disks

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2009-01-01

    An extrasolar planet sculpts the famous debris disk around Fomalhaut; probably many other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. But the interaction between planets and debris disks involves both orbital resonances and collisions among grains and rocks in the disks---difficult processes to model simultaneously. The author describes new 3-D models of debris disk dynamics, Drag-o-llision models, that incorporate both collisions and resonant trapping of dust for the first time. The author also discusses the implications of these models for coronagraphic imaging with Gemini and other telescopes.

  6. Homogeneous studies of transiting extrasolar planets - V. New results for 38 planets

    NASA Astrophysics Data System (ADS)

    Southworth, John

    2012-10-01

    I measure the physical properties of 38 transiting extrasolar planetary systems, bringing the total number studied within the Homogeneous Studies project to 82. Transit light curves are modelled using the JKTEBOP code, with careful attention paid to limb darkening, orbital eccentricity and contaminating light. The physical properties of each system are obtained from the photometric parameters, published spectroscopic measurements and five sets of theoretical stellar model predictions. Statistical errors are assessed using Monte Carlo and residual permutation algorithms and propagated via a perturbation algorithm. Systematic errors are estimated from the interagreement between results calculated using five theoretical stellar models. The headline result is a major upward revision of the radius of the planet in the OGLE-TR-56 system, from 1.23-1.38 to 1.734 ± 0.051 ± 0.029 RJup (statistical and systematic errors, respectively). Its density is three times lower than previously thought. This change comes from the first complete analysis of published high-quality photometry. Significantly larger planetary radii are also found for Kepler-15, KOI-428, WASP-13, WASP-14 and WASP-21 compared to previous work. I present the first results based on Kepler short-cadence data for Kepler-14, Kepler-15 and KOI-135. More extensive long-cadence data from the Kepler satellite are used to improve the measured properties of KOI-196, KOI-204, KOI-254, KOI-423 and KOI-428. The stellar component in the KOI-428 system is the largest known to host a transiting planet, at 2.48 ± 0.17 ± 0.20 R⊙. Detailed analyses are given for HAT-P-3, HAT-P-6, HAT-P-9, HAT-P-14 and WASP-12, based on more extensive data sets than considered in previous studies. Detailed analyses are also presented for the CoRoT systems 17, 18, 19, 20 and 23; Kepler-7, -12 and -17; KOI-254; OGLE-TR-111, -113, -132 and L9 and TrES-4. I revisit the correlations between orbital period and surface gravity, and orbital period

  7. Transit Search of 10,000 Stars for ExtraSolar Planets

    NASA Astrophysics Data System (ADS)

    Borucki, W. J.; Caldwell, D. A.; Koch, D. G.; Stout-Batalha, N. M.; Jenkins, J. M.; Showen, R. L.

    2000-12-01

    Doppler velocity searches for extrasolar planets have discovered over fifty planets orbiting solar-like stars. Combining the size determined from transit detections with the mass determined from Doppler velocity measurements yields the density of the extrasolar planet. With the orbital period and characteristics of the central star, these quantities provide a critical test of current theories of planetary structure. Observations of the planet orbiting HD209458 give an estimate of 0.3 g/cc, in agreement with theories of a planet that either formed near the central star or migrated there very shortly after formation. Several transit searches to discover extrasolar planets and determine their sizes are underway. Our Vulcan photometer at Lick Observatory has a 10-cm aperture, a 49-sq. degree FOV, and has monitored three different star fields for several weeks each for two years. Over 10,000 stars brighter than 12th magnitude have been observed with a precision adequate to detect Jovian-size planets. Hundreds of eclipsing binaries have been found. Over a dozen binaries showing transits with amplitudes as small as those expected for planetary companions demonstrate that the precision attained by the measurements is sufficient. Identification of these companions as grazing binaries or high area-ratio binaries has been accomplished. (See the meeting paper by Posson-Brown et al.) Early estimates of the frequency of planets with orbital periods less than a week ranged from 2 1 geometrical probability near 10 after including missed transits and the fraction of stars that are binaries with short periods or giants, discovery of a few planetary companions are expected. Currently we are investigating several candidates that show low amplitude transits. This project is funded by the NASA Origins and Astrobiology programs.

  8. All in the Family: What Brown Dwarfs Teach Us About Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, M.

    2003-01-01

    As we await the first direct image of an extrasolar giant planet, we can turn to theory and the experience gained in the campaign to detect and understand brown dwarfs for guidance on what to expect. As with any new arrival to a family, there should be a strong family resemblance (one hopes) along with notable unique features and interesting peculiarities. The 300 or so known L and T dwarfs, combined with our own giant planets, already span much of the effective temperature range within which extrasolar planets will be found. Only objects with thick, easily detectable, water clouds have yet to be seen. Thus we already know much of the family. I will describe what we have learned from studying these objects, focusing on the important roles clouds and atmospheric chemistry play in affecting their atmospheres and emergent spectra. Relying on these findings and theoretical models, I'll sketch out what we can expect from extrasolar giant planets, focusing on easily detectable features. Some wild cards, of course, are to be expected. Photochemical hazes, in particular, may obscure the family traits on the faces of Jupiter's distant cousins and may make one wonder, at least momentarily, about the milkman.

  9. Kepler Mission Discovers Trove of Extrasolar Planet Candidates

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-02-01

    NASA's Kepler discovery mission is collecting more than just pennies from heaven. Results from the first 4 months of science operations of the Kepler space telescope, announced on 2 February, include the discovery of 1235 candidate planets orbiting 997 stars in a small portion of the Milky Way galaxy examined by the telescope. Follow-up observations likely could confirm about 80% of the candidates as actual planets rather than false positives, according to researchers. This new trove of possible exoplanets could greatly expand the number of known planets outside of our solar system.

  10. 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

  11. Planets around Low-mass Stars. III. A Young Dusty L Dwarf Companion at the Deuterium-burning Limit

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.

    2013-09-01

    We report the discovery of an L-type companion to the young M3.5V star 2MASS J01225093-2439505 at a projected separation of 1.''45 (≈52 AU) as part of our adaptive optics imaging search for extrasolar giant planets around young low-mass stars. 2MASS 0122-2439 B has very red near-infrared colors similar to the HR 8799 planets and the reddest known young/dusty L dwarfs in the field. Moderate-resolution (R ≈ 3800) 1.5-2.4 μm spectroscopy reveals a near-infrared spectral type of L4-L6 and an angular H-band shape, confirming its cool temperature and young age. The kinematics of 2MASS 0122-2439 AB are marginally consistent with members of the ~120 Myr AB Dor young moving group based on the photometric distance to the primary (36 ± 4 pc) and our radial velocity measurement of 2MASS 0122-2439 A from Keck/HIRES. We adopt the AB Dor group age for the system, but the high energy emission, lack of Li I λ6707 absorption, and spectral shape of 2MASS 0122-2439 B suggest a range of ~10-120 Myr is possible. The age and luminosity of 2MASS 0122-2439 B fall in a strip where "hot-start" evolutionary model mass tracks overlap as a result of deuterium burning. Several known substellar companions also fall in this region (2MASS J0103-5515 ABb, AB Pic b, κ And b, G196-3 B, SDSS 2249+0044 B, LP 261-75 B, HD 203030 B, and HN Peg B), but their dual-valued mass predictions have largely been unrecognized. The implied mass of 2MASS 0122-2439 B is ≈12-13 M Jup or ≈22-27 M Jup if it is an AB Dor member, or possibly as low as 11 M Jup if the wider age range is adopted. Evolutionary models predict an effective temperature for 2MASS 0122-2439 B that corresponds to spectral types near the L/T transition (≈1300-1500 K) for field objects. However, we find a mid-L near-infrared spectral type, indicating that 2MASS 0122-2439 B represents another case of photospheric dust being retained to cooler temperatures at low surface gravities, as seen in the spectra of young (8-30 Myr) planetary

  12. PLANETS AROUND LOW-MASS STARS. III. A YOUNG DUSTY L DWARF COMPANION AT THE DEUTERIUM-BURNING LIMIT ,

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.

    2013-09-01

    We report the discovery of an L-type companion to the young M3.5V star 2MASS J01225093-2439505 at a projected separation of 1.''45 ( Almost-Equal-To 52 AU) as part of our adaptive optics imaging search for extrasolar giant planets around young low-mass stars. 2MASS 0122-2439 B has very red near-infrared colors similar to the HR 8799 planets and the reddest known young/dusty L dwarfs in the field. Moderate-resolution (R Almost-Equal-To 3800) 1.5-2.4 {mu}m spectroscopy reveals a near-infrared spectral type of L4-L6 and an angular H-band shape, confirming its cool temperature and young age. The kinematics of 2MASS 0122-2439 AB are marginally consistent with members of the {approx}120 Myr AB Dor young moving group based on the photometric distance to the primary (36 {+-} 4 pc) and our radial velocity measurement of 2MASS 0122-2439 A from Keck/HIRES. We adopt the AB Dor group age for the system, but the high energy emission, lack of Li I {lambda}6707 absorption, and spectral shape of 2MASS 0122-2439 B suggest a range of {approx}10-120 Myr is possible. The age and luminosity of 2MASS 0122-2439 B fall in a strip where ''hot-start'' evolutionary model mass tracks overlap as a result of deuterium burning. Several known substellar companions also fall in this region (2MASS J0103-5515 ABb, AB Pic b, {kappa} And b, G196-3 B, SDSS 2249+0044 B, LP 261-75 B, HD 203030 B, and HN Peg B), but their dual-valued mass predictions have largely been unrecognized. The implied mass of 2MASS 0122-2439 B is Almost-Equal-To 12-13 M{sub Jup} or Almost-Equal-To 22-27 M{sub Jup} if it is an AB Dor member, or possibly as low as 11 M{sub Jup} if the wider age range is adopted. Evolutionary models predict an effective temperature for 2MASS 0122-2439 B that corresponds to spectral types near the L/T transition ( Almost-Equal-To 1300-1500 K) for field objects. However, we find a mid-L near-infrared spectral type, indicating that 2MASS 0122-2439 B represents another case of photospheric dust being

  13. PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Tamura, Motohide

    2015-01-01

    We present results from a high-contrast adaptive optics imaging search for giant planets and brown dwarfs (≳1 M {sub Jup}) around 122 newly identified nearby (≲40 pc) young M dwarfs. Half of our targets are younger than 135 Myr and 90% are younger than the Hyades (620 Myr). After removing 44 close stellar binaries (implying a stellar companion fraction of >35.4% ± 4.3% within 100 AU), 27 of which are new or spatially resolved for the first time, our remaining sample of 78 single M dwarfs makes this the largest imaging search for planets around young low-mass stars (0.1-0.6 M {sub ☉}) to date. Our H- and K-band coronagraphic observations with Keck/NIRC2 and Subaru/HiCIAO achieve typical contrasts of 12-14 mag and 9-13 mag at 1'', respectively, which correspond to limiting planet masses of 0.5-10 M {sub Jup} at 5-33 AU for 85% of our sample. We discovered four young brown dwarf companions: 1RXS J235133.3+312720 B (32 ± 6 M {sub Jup}; L0{sub −1}{sup +2}; 120 ± 20 AU), GJ 3629 B (64{sub −23}{sup +30} M {sub Jup}; M7.5 ± 0.5; 6.5 ± 0.5 AU), 1RXS J034231.8+121622 B (35 ± 8 M {sub Jup}; L0 ± 1; 19.8 ± 0.9 AU), and 2MASS J15594729+4403595 B (43 ± 9 M {sub Jup}; M8.0 ± 0.5; 190 ± 20 AU). Over 150 candidate planets were identified; we obtained follow-up imaging for 56% of these but all are consistent with background stars. Our null detection of planets enables strong statistical constraints on the occurrence rate of long-period giant planets around single M dwarfs. We infer an upper limit (at the 95% confidence level) of 10.3% and 16.0% for 1-13 M {sub Jup} planets between 10-100 AU for hot-start and cold-start (Fortney) evolutionary models, respectively. Fewer than 6.0% (9.9%) of M dwarfs harbor massive gas giants in the 5-13 M {sub Jup} range like those orbiting HR 8799 and β Pictoris between 10-100 AU for a hot-start (cold-start) formation scenario. The frequency of brown dwarf (13-75 M {sub Jup}) companions to single

  14. Planets around Low-mass Stars (PALMS). IV. The Outer Architecture of M Dwarf Planetary Systems

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Tamura, Motohide

    2015-01-01

    We present results from a high-contrast adaptive optics imaging search for giant planets and brown dwarfs (gsim1 M Jup) around 122 newly identified nearby (lsim40 pc) young M dwarfs. Half of our targets are younger than 135 Myr and 90% are younger than the Hyades (620 Myr). After removing 44 close stellar binaries (implying a stellar companion fraction of >35.4% ± 4.3% within 100 AU), 27 of which are new or spatially resolved for the first time, our remaining sample of 78 single M dwarfs makes this the largest imaging search for planets around young low-mass stars (0.1-0.6 M ⊙) to date. Our H- and K-band coronagraphic observations with Keck/NIRC2 and Subaru/HiCIAO achieve typical contrasts of 12-14 mag and 9-13 mag at 1'', respectively, which correspond to limiting planet masses of 0.5-10 M Jup at 5-33 AU for 85% of our sample. We discovered four young brown dwarf companions: 1RXS J235133.3+312720 B (32 ± 6 M Jup; L0+2-1; 120 ± 20 AU), GJ 3629 B (64+30-23 M Jup; M7.5 ± 0.5; 6.5 ± 0.5 AU), 1RXS J034231.8+121622 B (35 ± 8 M Jup; L0 ± 1; 19.8 ± 0.9 AU), and 2MASS J15594729+4403595 B (43 ± 9 M Jup; M8.0 ± 0.5; 190 ± 20 AU). Over 150 candidate planets were identified; we obtained follow-up imaging for 56% of these but all are consistent with background stars. Our null detection of planets enables strong statistical constraints on the occurrence rate of long-period giant planets around single M dwarfs. We infer an upper limit (at the 95% confidence level) of 10.3% and 16.0% for 1-13 M Jup planets between 10-100 AU for hot-start and cold-start (Fortney) evolutionary models, respectively. Fewer than 6.0% (9.9%) of M dwarfs harbor massive gas giants in the 5-13 M Jup range like those orbiting HR 8799 and β Pictoris between 10-100 AU for a hot-start (cold-start) formation scenario. The frequency of brown dwarf (13-75 M Jup) companions to single M dwarfs between 10-100 AU is 2.8+2.4-1.5%. Altogether we find that giant planets, especially massive ones, are rare

  15. Fundmental Parameters of Low-Mass Stars, Brown Dwarfs, and Planets

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin; Johnson, John A.; Bowler, Brendan; Shkolnik, Evgenya

    2016-01-01

    Despite advances in evolutionary models of low-mass stars and brown dwarfs, these models remain poorly constrained by observations. In order to test these predictions directly, masses of individual stars must be measured and combined with broadband photometry and medium-resolution spectroscopy to probe stellar atmospheres. I will present results from an astrometric and spectroscopic survey of low-mass pre-main sequence binary stars to measure individual dynamical masses and compare to model predictions. This is the first systematic test of a large number of stellar systems of intermediate age between young star-forming regions and old field stars. Stars in our sample are members of the Tuc-Hor, AB Doradus, and beta Pictoris moving groups, the last of which includes GJ 3305 AB, the wide binary companion to the imaged exoplanet host 51 Eri. I will also present results of Spitzer observations of secondary eclipses of LHS 6343 C, a T dwarf transiting one member of an M+M binary in the Kepler field. By combining these data with Kepler photometry and radial velocity observations, we can measure the luminosity, mass, and radius of the brown dwarf. This is the first non-inflated brown dwarf for which all three of these parameters have been measured, providing the first benchmark to test model predictions of the masses and radii of field T dwarfs. I will discuss these results in the context of K2 and TESS, which will find additional benchmark transiting brown dwarfs over the course of their missions, including a description of the first planet catalog developed from K2 data and a program to search for transiting planets around mid-M dwarfs.

  16. DETECTING PLANETS AROUND VERY LOW MASS STARS WITH THE RADIAL VELOCITY METHOD

    SciTech Connect

    Reiners, A.; Bean, J. L.; Dreizler, S.; Seifahrt, A.; Huber, K. F.; Czesla, S.

    2010-02-10

    The detection of planets around very low-mass stars with the radial velocity (RV) method is hampered by the fact that these stars are very faint at optical wavelengths where the most high-precision spectrometers operate. We investigate the precision that can be achieved in RV measurements of low mass stars in the near-infrared (NIR) Y-, J-, and H-bands, and we compare it to the precision achievable in the optical assuming comparable telescope and instrument efficiencies. For early-M stars, RV measurements in the NIR offer no or only marginal advantage in comparison with optical measurements. Although they emit more flux in the NIR, the richness of spectral features in the optical outweighs the flux difference. We find that NIR measurement can be as precise as optical measurements in stars of spectral type {approx}M4, and from there the NIR gains in precision toward cooler objects. We studied potential calibration strategies in the NIR finding that a stable spectrograph with a ThAr calibration can offer enough wavelength stability for m s{sup -1} precision. Furthermore, we simulate the wavelength-dependent influence of activity (cool spots) on RV measurements from optical to NIR wavelengths. Our spot simulations reveal that the RV jitter does not decrease as dramatically toward longer wavelengths as often thought. The jitter strongly depends on the details of the spots, i.e., on spot temperature and the spectral appearance of the spot. At low temperature contrast ({approx}200 K), the jitter shows a decrease toward the NIR up to a factor of 10, but it decreases substantially less for larger temperature contrasts. Forthcoming NIR spectrographs will allow the search for planets with a particular advantage in mid- and late-M stars. Activity will remain an issue, but simultaneous observations at optical and NIR wavelengths can provide strong constraints on spot properties in active stars.

  17. 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

  18. Transits of extrasolar moons around luminous giant planets

    NASA Astrophysics Data System (ADS)

    Heller, R.

    2016-04-01

    Beyond Earth-like planets, moons can be habitable, too. No exomoons have been securely detected, but they could be extremely abundant. Young Jovian planets can be as hot as late M stars, with effective temperatures of up to 2000 K. Transits of their moons might be detectable in their infrared photometric light curves if the planets are sufficiently separated (≳10 AU) from the stars to be directly imaged. The moons will be heated by radiation from their young planets and potentially by tidal friction. Although stellar illumination will be weak beyond 5 AU, these alternative energy sources could liquify surface water on exomoons for hundreds of Myr. A Mars-mass H2O-rich moon around β Pic b would have a transit depth of 1.5 × 10-3, in reach of near-future technology.

  19. Ten years of quests for radio bursts from extrasolar planets

    NASA Astrophysics Data System (ADS)

    Shiratori, Y.; Yokoo, H.; Saso, T.; Kameya, O.; Iwadate, K.; Asari, K.

    2006-02-01

    We searched for radio bursts towards 51 Peg, τ Boo, ν And and 55 Cancri, which were found to have "hot Jupiter" companions. The star 51 Peg has a planet with 0.5 M_{Jup} (lower limit) and 4.23 day period. The star τ Boo has a planet of 3.7 M_{Jup} and 3.31 day period. Such planets are called "Hot Jupiter". We made a non-thermal radio emission model of magneto-electric environment between the stars and their planets. Since a detection of signals is expected, we made observations at 8.6 GHz with Mizusawa 10-m telescope. From 1996 to 2000, we observed with a detection limit of 10 Jy using a position-switching method. Since 2001, we changed to beam-switching method, and achieved a detection limit of 1 Jy. No radio burst signals were detected.

  20. Delivery of Volatiles to Habitable Planets in Extrasolar Planetary Systems

    NASA Technical Reports Server (NTRS)

    Chambers, John E.; Kress, Monika E.; Bell, K. Robbins; Cash, Michele; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The Earth can support life because: (1) its orbit lies in the Sun's habitable zone', and (2) it contains enough volatile material (e.g. water and organics) for life to flourish. However, it seems likely that the Earth was drier when it formed because it accreted in a part of the Sun's protoplanetary nebula that was too hot for volatiles to condense. If this is correct, water and organics must have been delivered to the habitable zone, after dissipation of the solar nebula, from a 'wet zone' in the asteroid belt or the outer solar system, where the nebula was cool enough for volatiles to condense. Material from the wet zone would have been delivered to the Earth by Jupiter and Saturn. Gravitational perturbations from these giant planets made much of the wet zone unstable, scattering volatile-rich planetesimals and protoplanets across the Solar System. Some of these objects ultimately collided with the inner Planets which themselves lie in a stable part of the Solar System. Giant planets are now being discovered orbiting other sunlike stars. To date, these planets have orbits and masses very different from Jupiter and Saturn, such that few if any of these systems is likely to have terrestrial planets in the star's habitable zone. However, new discoveries are anticipated due to improved detector sensitivity and the increase in the timespan of observations. Here we present numerical experiments examining the range of giant-planet characteristics that: (1) allow stable terrestrial Planets to exist in a star's habitable zone, and (2) make a large part of the star's wet zone weakly unstable, thus delivering volatiles to the terrestrial planets over an extended period of time after the dissipation of the solar nebula.

  1. 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.

  2. 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.

  3. Short-Term Dynamical Interactions Among Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Laughlin, Gregory; Chambers, John E.; DiVincenzi, Donald (Technical Monitor)

    2001-01-01

    We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star which differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two alternate fitting methods which can lead to an improved dynamical description of multiple planet systems. In the first method, the osculating orbital elements are determined via a Levenberg-Marquardt minimization scheme driving an N-body integrator. The second method is an improved analytic model in which orbital elements such as the periods and longitudes of periastron are allowed to vary according to a simple model for resonant interactions between the planets. Both of these methods can potentially determine the true masses for the planets by eliminating the sin(i) degeneracy inherent in fits that assume independent Keplerian motions. As more radial velocity data is accumulated from stars such as GJ876, these methods should allow for unambiguous determination of the planetary masses and relative inclinations.

  4. 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.

  5. 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.

  6. Evidence for water in the rocky debris of a disrupted extrasolar minor planet.

    PubMed

    Farihi, J; Gänsicke, B T; Koester, D

    2013-10-11

    The existence of water in extrasolar planetary systems is of great interest because it constrains the potential for habitable planets and life. We have identified a circumstellar disk that resulted from the destruction of a water-rich and rocky extrasolar minor planet. The parent body formed and evolved around a star somewhat more massive than the Sun, and the debris now closely orbits the white dwarf remnant of the star. The stellar atmosphere is polluted with metals accreted from the disk, including oxygen in excess of that expected for oxide minerals, indicating that the parent body was originally composed of 26% water by mass. This finding demonstrates that water-bearing planetesimals exist around A- and F-type stars that end their lives as white dwarfs. PMID:24115434

  7. 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.

  8. Practical High-Order Adaptive Optics Systems For Extrasolar Planet Searches

    SciTech Connect

    Macintosh, B A; Olivier, S; Bauman, B; Brase, J; Carr, E; Carrano, C J; Gavel, D; Max, C E; Patience, J

    2001-08-29

    Direct detection of photons emitted or reflected by an extrasolar planet is an extremely difficult but extremely exciting application of adaptive optics. Typical contrast levels for an extrasolar planet would be 10{sup 9}-Jupiter is a billion times fainter than the sun. Current adaptive optics systems can only achieve contrast levels of 10{sup 6}, but so-called ''extreme'' adaptive optics systems with 10{sup 4}-10{sup 5} degrees of freedom could potentially detect extrasolar planets. We explore the scaling laws defining the performance of these systems, first set out by Angel (1994), and derive a different definition of an optimal system. Our sensitivity predictions are somewhat more pessimistic than the original paper, due largely to slow decorrelation timescales for some noise sources, though choosing to site an ExAO system at a location with exceptional r{sub 0} (e.g. Mauna Kea) can offset this. We also explore the effects of segment aberrations in a Keck-like telescope on ExAO; although the effects are significant, they can be mitigated through Lyot coronagraphy.

  9. Model Atmospheres and Spectra for Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Freedman, Richard S.; Beebe, Reta (Technical Monitor)

    2000-01-01

    In the past few years much new observational data has become available for brown dwarfs and extra solar planets. Not only are new objects being discovered but the availability of higher resolution spectra is improving. This allows a better comparison between the models and the available data, and places new constraints on the models which now have to be made more physically realistic in order to better interpret the observations. Under this grant, an array of new opacities were calculated and successfully applied to a variety of physical situations that were used as input to model available observations of brown dwarfs and extra solar giant planets.

  10. Direct and interferometric imaging approaches for detecting earth-like extrasolar planets

    NASA Technical Reports Server (NTRS)

    Diner, D. J.; Van Zyl, J.; Jones, D. L.; Tubbs, E.; Wright, V.

    1988-01-01

    This paper discusses functional requirements of space-based observational systems with sufficient sensitivity, resolution, and dynamic range to image earth-like extrasolar planets within a search radius of 10 parsecs from the sun. Both direct and interferometric systems operating at visible and infrared wavelengths are evaluated, and the methods used to establish the system tolerances are presented. Due to the more favorable star/planet contrast ratio in the infrared, optical tolerance requirements are less stringent than in the visible. However, reduction of thermal radiation from the telescope requires cooling of the primary optics. Other tradeoffs between various approaches are enumerated.

  11. An Adaptive Optics Survey for Companions to Stars with Extra-Solar Planets

    SciTech Connect

    Lloyd, J.P.; Liu, M.C.; Graham, J.R.; Enoch, M.; Kalas, P.; Marcy, G.W.; Fischer, D.; Patience, J.; Macintosh, B.; Gavel, D.T.; Olivier, S.S.; Max, C.E.; White, R.; Ghez, A.M.; McLean, I.S.

    2000-11-27

    We have undertaken an adaptive optics imaging survey of extrasolar planetary systems and stars showing interesting radial velocity trends from high precision radial velocity searches. Adaptive Optics increases the resolution and dynamic range of an image, substantially improving the detectability of faint close companions. This survey is sensitive to objects less luminous than the bottom of the main sequence at separations as close as 1 inch. We have detected stellar companions to the planet bearing stars HD 114762 and Tau Boo. We have also detected a companion to the non-planet bearing star 16 Cyg A.

  12. Adaptive Optics Survey for Companions to stars with Extra-Solar Planets

    SciTech Connect

    Lloyd, J P; Liu, M C; Graham, J R; Enoch, M; Kalas, P; Marcy, G W; Fischer, D; Patience, J; Macintosh, B; Gavel, D T; Olivier, S S; Max, C E; White, R; Ghez, A M; McLean, I S

    2000-11-27

    We have undertaken an adaptive optics imaging survey of extrasolar planetary systems and stars showing interesting radial velocity trends from high precision radial velocity searches. Adaptive Optics increases the resolution and dynamic range of an image, substantially improving the detectability of faint close companions. This survey is sensitive to objects less luminous than the bottom of the main sequence at separations as close as 1 inch. We have detected stellar companions to the planet bearing stars HD 114762 and Tau Boo. We have also detected a companion to the non-planet bearing star 16 Cyg A.

  13. 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.

  14. 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.

  15. Imaging Extra-Solar Planets with an Ultra-Large Space Telescope

    NASA Technical Reports Server (NTRS)

    Taylor, Charles R.

    1998-01-01

    NASA's Origins Program is directed toward two main goals: Imaging of galactic evolution in the early universe, and searching for planets orbiting nearby stars. The Next-Generation Space Telescope (NGST), operating at low temperature with an 8-m aperture, is well designed to meet the first goal. The goal of imaging planets orbiting nearby stars is more problematic. One line of investigation has been the ULTIMA concept (Ultra-Large Telescope, Integrated Missions in Astronomy). In this report, I will lay out the resolution requirements for telescopes to achieve the imaging of extrasolar planets, and describe a modeling tool created to investigate the requirements for imaging a planet when it is very near a much brighter star.

  16. Habitability of extrasolar planets and tidal spin evolution.

    PubMed

    Heller, René; Barnes, Rory; Leconte, Jérémy

    2011-12-01

    Stellar radiation has conservatively been used as the key constraint to planetary habitability. We review here the effects of tides, exerted by the host star on the planet, on the evolution of the planetary spin. Tides initially drive the rotation period and the orientation of the rotation axis into an equilibrium state but do not necessarily lead to synchronous rotation. As tides also circularize the orbit, eventually the rotation period does equal the orbital period and one hemisphere will be permanently irradiated by the star. Furthermore, the rotational axis will become perpendicular to the orbit, i.e. the planetary surface will not experience seasonal variations of the insolation. We illustrate here how tides alter the spins of planets in the traditional habitable zone. As an example, we show that, neglecting perturbations due to other companions, the Super-Earth Gl581d performs two rotations per orbit and that any primordial obliquity has been eroded. PMID:22139513

  17. ON THE HORSESHOE DRAG OF A LOW-MASS PLANET. I. MIGRATION IN ISOTHERMAL DISKS

    SciTech Connect

    Casoli, J.; Masset, F. S. E-mail: frederic.masset@cea.f

    2009-09-20

    We investigate the unsaturated horseshoe drag exerted on a low-mass planet by an isothermal gaseous disk. In the globally isothermal case, we use a formalism, based on the use of a Bernoulli invariant, that takes into account pressure effects, and that extends the torque estimate to a region wider than the horseshoe region. We find a result that is strictly identical to the standard horseshoe drag. This shows that the horseshoe drag accounts for the torque of the whole corotation region, and not only of the horseshoe region, thereby deserving to be called corotation torque. We find that evanescent waves launched downstream of the horseshoe U-turns by the perturbations of vortensity exert a feedback on the upstream region, that render the horseshoe region asymmetric. This asymmetry scales with the vortensity gradient and with the disk's aspect ratio. It does not depend on the planetary mass, and it does not have any impact on the horseshoe drag. Since the horseshoe drag has a steep dependence on the width of the horseshoe region, we provide an adequate definition of the width that needs to be used in horseshoe drag estimates. We then consider the case of locally isothermal disks, in which the temperature is constant in time but depends on the distance to the star. The horseshoe drag appears to be different from the case of a globally isothermal disk. The difference, which is due to the driving of vortensity in the vicinity of the planet, is intimately linked to the topology of the flow. We provide a descriptive interpretation of these effects, as well as a crude estimate of the dependency of the excess on the temperature gradient.

  18. Urey Prize Lecture: Orbital Dynamics of Extrasolar Planets, Large and Small

    NASA Astrophysics Data System (ADS)

    Ford, Eric B.

    2012-10-01

    For centuries, planet formation theories were fine tuned to explain the details of solar system. Since 1999, the Doppler technique has discovered dozens of multiple planet systems. The diversity of architectures of systems with giant planets challenged previous theories and led to insights into planet formation, orbital migration and the excitation of orbital eccentricities and inclinations. Recently, NASA's Kepler mission has identified over 300 systems with multiple transiting planet candidates, including many potentially rocky planets. Precise measurements of the orbital period and phase constrain the significance of mutual gravitational interactions and potential orbital resonances. For systems that are tightly-packed or near an orbital resonance, measurements of transit timing variations provide a new means for confirming transiting planets and detecting non-transiting planets in multiple planet systems, even around faint target stars. Over the course of the extended mission, Kepler is poised to measure the gravitational effects of mutual planetary perturbations for 200 planets, providing precise (but complex) constraints on planetary masses, densities and orbits. I will survey the systems with multiple transiting planet candidates identified by Kepler and discuss early efforts to translate these observations into new constraints on the formation and orbital evolution of planetary systems with low-mass planets.

  19. A stability limit for the atmospheres of giant extrasolar planets.

    PubMed

    Koskinen, Tommi T; Aylward, Alan D; Miller, Steve

    2007-12-01

    Recent observations of the planet HD209458b indicate that it is surrounded by an expanded atmosphere of atomic hydrogen that is escaping hydrodynamically. Theoretically, it has been shown that such escape is possible at least inside an orbit of 0.1 au (refs 4 and 5), and also that H3+ ions play a crucial role in cooling the upper atmosphere. Jupiter's atmosphere is stable, so somewhere between 5 and 0.1 au there must be a crossover between stability and instability. Here we show that there is a sharp breakdown in atmospheric stability between 0.14 and 0.16 au for a Jupiter-like planet orbiting a solar-type star. These results are in contrast to earlier modelling that implied much higher thermospheric temperatures and more significant evaporation farther from the star. (We use a three-dimensional, time-dependent coupled thermosphere-ionosphere model and properly include cooling by H3+ ions, allowing us to model globally the redistribution of heat and changes in molecular composition.) Between 0.2 and 0.16 au cooling by H3+ ions balances heating by the star, but inside 0.16 au molecular hydrogen dissociates thermally, suppressing the formation of H3+ and effectively shutting down that mode of cooling. PMID:18064005

  20. 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.

  1. Remote Sensing of Planetary Properties and Biosignatures on Extrasolar Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Des Marais, David J.; Harwit, Martin O.; Jucks, Kenneth W.; Kasting, James F.; Lin, Douglas N. C.; Lunine, Jonathan I.; Schneider, Jean; Seager, Sara; Traub, Wesley A.; Woolf, Neville J.

    2002-06-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 μm in the mid-IR and 0.5 to ~1.1 μm in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin.

  2. Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planets

    NASA Technical Reports Server (NTRS)

    Des Marais, David J.; Harwit, Martin O.; Jucks, Kenneth W.; Kasting, James F.; Lin, Douglas N C.; Lunine, Jonathan I.; Schneider, Jean; Seager, Sara; Traub, Wesley A.; Woolf, Neville J.

    2002-01-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 microns in the mid-IR and 0.5 to approximately 1.1 microns in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin.

  3. The Formation of Life-sustaining Planets in Extrasolar Systems

    NASA Technical Reports Server (NTRS)

    Chambers, J. E.

    2003-01-01

    The spatial exploration is providing us a large quantity of information about the composition of the planets and satellites crusts. However, most of the experiences that are proposed in the guides of activities in Planetary Geology are based exclusively on the images utilization: photographs, maps, models or artistic reconstructions [1,2]. That things help us to recognize shapes and to deduce geological processes, but they says us little about the materials that they are implicated. In order to avoid this dicotomy between shapes and materials, we have designed an experience in the one which, employing of rocks and landscapes of our geological environment more next, the pupils be able to do an exercise of compared planetology analyzing shapes, processes and material of several planetary bodies of the Solar System.

  4. Extrasolar Planets Observed with JWST and the ELTs

    NASA Technical Reports Server (NTRS)

    Deming, L. Drake

    2010-01-01

    The advent of cryogenic space-borne infrared observatories such as the Spitzer Space Telescope has lead to a revolution in the study of planets and planetary systems orbiting sun-like stars. Already Spitzer has characterized the emergent infrared spectra of close-in giant exoplanets using transit and eclipse techniques. The James Webb Space Telescope (JWST) will be able to extend these studies to superEarth exoplanets orbiting in the habitable zones of M-dwarf stars in the near solar neighborhood. The forthcoming ground-based Extremely Large Telescopes (ELTs) will playa key role in these studies, being especially valuable for spectroscopy at higher spectral resolving powers where large photon fluxes are needed. The culmination of this work within the next two decades will be the detection and spectral characterization of the major molecular constituents in the atmosphere of a habitable superEarth orbiting a nearby lower main sequence star.

  5. Atmosphere Models for the Brown Dwarf Gliese 229 B and the Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.

    1996-01-01

    Brown dwarfs inhabit a realm intermediate between the more massive stars and the less massive planets. Their thermal infrared emission is powered by the release of gravitational potential energy as regulated by their atmospheres. Long known only as theoretical constructs. the discovery of the first unimpeachable brown dwarf. Gliese 229 has opened up a new field: the study of brown dwarf atmospheres. The subsequent discoverv of numerous extrasolar giant planets circling nearby stars, further demonstrated the need for a comprehensive modeling effort to understand this new class of jovian atmospheres. Although no spectra are yet available of the new planets, the next generation of groundbased and spacebased telescopes will return such data. Here author report on the effort with Ames collaborator Dr. Christopher McKay to better understand these new atmospheres.

  6. Quests for Radio Bursts towards the Extra-Solar Planets (51 Peg and tau Boo)

    NASA Astrophysics Data System (ADS)

    Shiratori, Y.; Yokoo, H.; Sasao, T.; Kameya, O.; Tamura, Y.; Iwadate, K.; Fujishita, M.; Matsumoto, K.; Yoshikawa, T.; Matsumae, Y.

    We searched for radio bursts towards 51 Peg and /tau Boo, which were found as extra-solar planets in 1995. 51 Peg (G2-3V, its distance is 40 light years) is expected to have a planet with 0.5 Jupiter mass (lower limit) and 4.2308 day period, which is called "Hot Jupiter". Tau Boo is to have that with 3.7 Jupiter mass and 3.31 day period. We made a non-thrmal radio emission model of magnetoelectric environment between the stars and their planets. Since a detection of signals is expected. we made obseravations at 8.6 GHz in Sep. and Nov. of last year for 141 hours and 155 hours each with Mizusawa 10-m telescope. During the November observation, we observaed to 10 Jy as an S/N ratio using a position switching method. And we got a possible burst signals, which might be different from artificial ones.

  7. VizieR Online Data Catalog: Spectropolarimetric signatures of Earth--like extrasolar planets.

    NASA Astrophysics Data System (ADS)

    Stam, D. M.

    Numerically calculated scattering matrix elements a1 and b1 of 11 different types of Earth-like extrasolar planets are presented. Matrix element a1 is proportional to the total flux that is reflected by the exoplanet, matrix element b1 is proportional to the linearly polarized flux. Also given is the ratio -b1/a1, which is the degree of linear polarization of the light that is reflected by the exoplanet. Each directory contains 91 ASCII files: one file for each planetary phase angle. The phase angles range from 0 degrees ("a full planet") to 180 degrees ("a new planet"), in steps of 2 degrees. Files are labelled DDDAAN.txt, where DDD is the phase angle and AAN the model code (000fo0.txt for 0 degrees in forest0 model, 000oc0.txt for 0 degrees in ocean_0 model, 000000.txt for 0 degrees in lambert000 model). (11 data files).

  8. Three regimes of extrasolar planet radius inferred from host star metallicities.

    PubMed

    Buchhave, Lars A; Bizzarro, Martin; Latham, David W; Sasselov, Dimitar; Cochran, William D; Endl, Michael; Isaacson, Howard; Juncher, Diana; Marcy, Geoffrey W

    2014-05-29

    Approximately half of the extrasolar planets (exoplanets) with radii less than four Earth radii are in orbits with short periods. Despite their sheer abundance, the compositions of such planets are largely unknown. The available evidence suggests that they range in composition from small, high-density rocky planets to low-density planets consisting of rocky cores surrounded by thick hydrogen and helium gas envelopes. Here we report the metallicities (that is, the abundances of elements heavier than hydrogen and helium) of more than 400 stars hosting 600 exoplanet candidates, and find that the exoplanets can be categorized into three populations defined by statistically distinct (∼4.5σ) metallicity regions. We interpret these regions as reflecting the formation regimes of terrestrial-like planets (radii less than 1.7 Earth radii), gas dwarf planets with rocky cores and hydrogen-helium envelopes (radii between 1.7 and 3.9 Earth radii) and ice or gas giant planets (radii greater than 3.9 Earth radii). These transitions correspond well with those inferred from dynamical mass estimates, implying that host star metallicity, which is a proxy for the initial solids inventory of the protoplanetary disk, is a key ingredient regulating the structure of planetary systems. PMID:24870544

  9. Three regimes of extrasolar planet radius inferred from host star metallicities

    PubMed Central

    Buchhave, Lars A.; Bizzarro, Martin; Latham, David W.; Sasselov, Dimitar; Cochran, William D.; Endl, Michael; Isaacson, Howard; Juncher, Diana; Marcy, Geoffrey W.

    2014-01-01

    Approximately half of the extrasolar planets (exoplanets) with radii less than four Earth radii are in orbits with short periods1. Despite their sheer abundance, the compositions of such planets are largely unknown. The available evidence suggests that they range in composition from small, high-density rocky planets to low-density planets consisting of rocky cores surrounded by thick hydrogen and helium gas envelopes. Here we report the metallicities (that is, the abundances of elements heavier than hydrogen and helium) of more than 400 stars hosting 600 exoplanet candidates, and find that the exoplanets can be categorized into three populations defined by statistically distinct (~4.5σ) metallicity regions. We interpret these regions as reflecting the formation regimes of terrestrial-like planets (radii less than 1.7 Earth radii), gas dwarf planets with rocky cores and hydrogen-helium envelopes (radii between 1.7 and 3.9 Earth radii) and ice or gas giant planets (radii greater than 3.9 Earth radii). These transitions correspond well with those inferred from dynamical mass estimates2,3, implying that host star metallicity, which is a proxy for the initial solids inventory of the protoplanetary disk, is a key ingredient regulating the structure of planetary systems. PMID:24870544

  10. Hot Jupiter breezes: time-dependent outflows from extrasolar planets

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Adams, Fred C.

    2016-03-01

    We explore the dynamics of magnetically controlled outflows from hot Jupiters, where these flows are driven by UV heating from the central star. In these systems, some of the open field lines do not allow the flow to pass smoothly through the sonic point, so that steady-state solutions do not exist in general. This paper focuses on this type of magnetic field configuration, where the resulting flow becomes manifestly time-dependent. We consider the case of both steady heating and time-variable heating, and find the time-scales for the corresponding time variations of the outflow. Because the flow cannot pass through the sonic transition, it remains subsonic and leads to so-called breeze solutions. One manifestation of the time variability is that the flow samples a collection of different breeze solutions over time, and the mass outflow rate varies in quasi-periodic fashion. Because the flow is subsonic, information can propagate inwards from the outer boundary, which determines, in part, the time-scale of the flow variability. This work finds the relationship between the outer boundary scale and the time-scale of flow variations. In practice, the location of the outer boundary is set by the extent of the sphere of influence of the planet. The measured time variability can be used, in principle, to constrain the parameters of the system (e.g. the strengths of the surface magnetic fields).

  11. Two Suns in the Sky: Many Extrasolar Planets Orbiting Stars in Multiple Systems

    NASA Astrophysics Data System (ADS)

    Raghavan, D.; Henry, T. J.; Subasavage, J.; Beaulieu, T.

    2003-12-01

    We present results of a reconnaissance for stellar and brown dwarf companions to 102 star systems with probable planets. Stars listed in the Extrasolar Planets Catalog (maintained by Jean Schneider, Paris Observatory) as of July 18, 2003 are being investigated in order to build a comprehensive list of new and known companions to each stellar primary. New common proper motion companions are found via the multi-epoch SuperCOSMOS and STScI Digitized Sky Surveys, and new photometric companions are found using 2MASS. We confirm or refute each known companion listed in the Washington Double Star (WDS) Catalog (the world's most comprehensive database on multiple stars), the Catalog of Nearby Stars (CNS), and Hipparcos. Preliminary findings indicate that as many as 32 out of the 102 systems (31 brown dwarf companions. In addition, we have detected 11 new possible companions in 8 of the star systems. We have also found evidence for 12 false entries of companions in WDS --- they do not show any related proper motion in the DSS plates. These results indicate that a careful inventory of the stars harboring extrasolar planets is needed, and that solar systems are likely to be found in a large number of multiple systems.

  12. A Spitzer Infrared Radius for the Transiting Extrasolar Planet HD 209458 b

    NASA Technical Reports Server (NTRS)

    Richardson, L. Jeremy; Harrington, Joseph; Seager, Sara; Deming, Drake

    2007-01-01

    We have measured the infrared transit of the extrasolar planet HD 209458 b using the Spitzer Space Telescope. We observed two primary eclipse events (one partial and one complete transit) using the 24 micrometer array of the Multiband Imaging Photometer for Spitzer (MIPS). We analyzed a total of 2392 individual images (10-second integrations) of the planetary system, recorded before, during, and after transit. We perform optimal photometry on the images and use the local zodiacal light as a short-term flux reference. At this long wavelength, the transit curve has a simple box-like shape, allowing robust solutions for the stellar and planetary radii independent of stellar limb darkening, which is negligible at 24 micrometers. We derive a stellar radius of R(sub *) = 1.06 plus or minus 0.07 solar radius, a planetary radius of R(sub p) = 1.26 plus or minus 0.08 R(sub J), and a stellar mass of 1.17 solar mass. Within the errors, our results agree with the measurements at visible wavelengths. The 24 micrometer radius of the planet therefore does not differ significantly compared to the visible result. We point out the potential for deriving extrasolar transiting planet radii to high accuracy using transit photometry at slightly shorter IR wavelengths where greater photometric precision is possible.

  13. Molecular Line and Continuum Opacities for Modeling of Extrasolar Giant Planet and Cool Stellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Weck, P. F.; Schweitzer, A.; Stancil, P. C.; Hauschildt, P. H.; Kirby, K.; Yamaguchi, Y.; Allen, W. D.

    2002-01-01

    The molecular line and continuum opacities are investigated in the atmospheres of cool stars and Extrasolar Giant Planets (EGPs). Using a combination of ab inito and experimentally derived potential curves and dipole transition moments, accurate data have been calculated for rovibrationally-resolved oscillator strengths and photodissociation cross sections in the B' (sup 2)Sigma+ (left arrow) X (sup 2)Sigma+ and A (sup 2)Pi (left arrow) X (sup 2)Sigma+ band systems in MgH. We also report our progress on the study of the electronic structure of LiCl and FeH.

  14. 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.

  15. Metal Hydride and Alkali Halide Opacities in Extrasolar Giant Planets and Cool Stellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Weck, Philippe F.; Stancil, Phillip C.; Kirby, Kate; Schweitzer, Andreas; Hauschildt, Peter H.

    2006-01-01

    The lack of accurate and complete molecular line and continuum opacity data has been a serious limitation to developing atmospheric models of cool stars and Extrasolar Giant Planets (EGPs). We report our recent calculations of molecular opacities resulting from the presence of metal hydrides and alkali halides. The resulting data have been included in the PHOENIX stellar atmosphere code (Hauschildt & Baron 1999). The new models, calculated using spherical geometry for all gravities considered, also incorporate our latest database of nearly 670 million molecular lines, and updated equations of state.

  16. Fast spin of the young extrasolar planet β Pictoris b.

    PubMed

    Snellen, Ignas A G; Brandl, Bernhard R; de Kok, Remco J; Brogi, Matteo; Birkby, Jayne; Schwarz, Henriette

    2014-05-01

    The spin of a planet arises from the accretion of angular momentum during its formation, but the details of this process are still unclear. In the Solar System, the equatorial rotation velocities and, consequently, spin angular momenta of most of the planets increase with planetary mass; the exceptions to this trend are Mercury and Venus, which, since formation, have significantly spun down because of tidal interactions. Here we report near-infrared spectroscopic observations, at a resolving power of 100,000, of the young extrasolar gas giant planet β Pictoris b (refs 7, 8). The absorption signal from carbon monoxide in the planet's thermal spectrum is found to be blueshifted with respect to that from the parent star by approximately 15 kilometres per second, consistent with a circular orbit. The combined line profile exhibits a rotational broadening of about 25 kilometres per second, meaning that β Pictoris b spins significantly faster than any planet in the Solar System, in line with the extrapolation of the known trend in spin velocity with planet mass. PMID:24784216

  17. MIGRATION OF EXTRASOLAR PLANETS: EFFECTS FROM X-WIND ACCRETION DISKS

    SciTech Connect

    Adams, Fred C.; Cai, Mike J.; Lizano, Susana

    2009-09-10

    Magnetic fields are dragged in from the interstellar medium during the gravitational collapse that forms star/disk systems. Consideration of mean field magnetohydrodynamics in these disks shows that magnetic effects produce sub-Keplerian rotation curves and truncate the inner disk. This Letter explores the ramifications of these predicted disk properties for the migration of extrasolar planets. Sub-Keplerian flow in gaseous disks drives a new migration mechanism for embedded planets and modifies the gap-opening processes for larger planets. This sub-Keplerian migration mechanism dominates over Type I migration for sufficiently small planets (m{sub P} {approx}< 1 M {sub +}) and/or close orbits (r {approx}< 1 AU). Although the inclusion of sub-Keplerian torques shortens the total migration time by only a moderate amount, the mass accreted by migrating planetary cores is significantly reduced. Truncation of the inner disk edge (for typical system parameters) naturally explains final planetary orbits with periods P {approx} 4 days. Planets with shorter periods, P {approx} 2 days, can be explained by migration during FU-Orionis outbursts, when the mass accretion rate is high and the disk edge moves inward. Finally, the midplane density is greatly increased at the inner truncation point of the disk (the X-point); this enhancement, in conjunction with continuing flow of gas and solids through the region, supports the in situ formation of giant planets.

  18. 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.

  19. The First Extrasolar Planet Discovered with A New Generation High Throughput Doppler Instrument

    NASA Astrophysics Data System (ADS)

    Ge, J.; van Eyken, J.; Mahadevan, S.; DeWitt, C.; Cohen, R.; Vanden Heuvel, A.; Fleming, S.; Guo, P.; Kane, S.; Henry, G.; Israelian, G.; Martin, E.

    2005-12-01

    We report the first extrasolar planet, ET1, detected with a new generation Doppler instrument, called Exoplanet Tracker. This planet has a minimum mass of 0.41 Jupiter masses and orbits a V = 8.1 K0V star with a 4.8 day period. The planet was identified using the KPNO Coude Feed 0.9 meter telescope in spring 2005. This is the first time an extrasolar planet around a star fainter than V=8 magnitude has been discovered with an under 1 meter size astronomical telescope and Doppler instrument. This planet discovery is possible due to the extremely high throughput of the instrument, nearly 50% measured from the fiber output end to the detector. This discovery enables a new generation radial-velocity survey that could detect thousands of exoplanets using multiple-object versions of the ET instruments, called the W.M. Keck Exoplanet Tracker, at large wide-field telescopes in 2006-2020. A prototype multiple object ET has already demonstrated a 25 object capability for precision Doppler measurements at the Sloan telescope in early 2005. The ET instrument design is based on dispersed fixed-delay interferometry (Ge 2002), which is evolved from the earlier externally dispersed interferometry (Erskine and Ge 2000; Ge, Erskine and Rushford 2002) and the Global Oscillation Net Work (GONG) interferometry (Barker & Hollenbach 1972; Gorskii & Lebedev 1977; Beckers & Brown 1978; Harvey et al., 1988; Harvey 2002 private communications). We acknowledge the excellent support from the KPNO and Sloan management, technical and observational staff. The ET project is supported by the University of Florida, NSF, Keck Foundation and NASA JPL (Michelson Fellowship Program).

  20. 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.

  1. A Framework For Characterizing The Atmospheres Of GJ 1214b-type Low-mass Low-density Transiting Planets

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Nettelmann, N.; Kempton, E.; Mordasini, C.; Zahnle, K.; Lopez, E.; Morley, C. V.; Marley, M. S.

    2012-10-01

    The atmosphere of the low-mass low-density transiting planet GJ 1214b has been extensively characterized via transmission spectroscopy. Observations include spectra and photometric points from blue to mid-infrared wavelengths. The transmission spectrum appears relatively featureless, indicating an atmosphere that does not show strong molecular absorption features. It has been suggested that this ``flat" spectrum could be due to an obscuring grey cloud/haze layer, or due to a high mean molecular weight (MMW) atmosphere. If the planet is similar to a scaled down version of Uranus or Neptune, as suggested by Nettelmann et al. (2011), both explanations could well be viable. To lift the degeneracy of these explanations, one can imagine characterizing a range of similar planets, which are now being found. Here we examine the structure and atmospheres of volatile-rich planets from 5-20 Earth masses and T_eq from 100 - 1500 K. Based on population synthesis models of core-accretion planet formation, we examine the expected Z_atmosphere and MMW these low mass planets. We examine how atmospheric escape of the outermost layers of such planets may expose deeper atmospheric layers with less hydrogen and a higher Z_atmosphere and MMW. We note that the hottest variants of these planets should feature atmospheres rich in CO, rather than CH4, potentially eliminating a pathway to photochemical haze formation. We provide a synthesis of these physical effects over a range of mass, temperature, and metallicity parameters. We highlight where in parameter space these GJ 1214b and Neptune-like planets are likely to have atmospheres that are most amenable to characterization from transmission spectroscopy.

  2. THE EFFECT OF MASS LOSS ON THE TIDAL EVOLUTION OF EXTRASOLAR PLANET

    SciTech Connect

    Guo, J. H.

    2010-04-01

    By combining mass loss and tidal evolution of close-in planets, we present a qualitative study on their tidal migrations. We incorporate mass loss in tidal evolution for planets with different masses and find that mass loss could interfere with tidal evolution. In an upper limit case (beta = 3), a significant portion of mass may be evaporated in a long evolution timescale. Evidence of greater modification of the planets with an initial separation of about 0.1 AU than those with a = 0.15 AU can be found in this model. With the assumption of a large initial eccentricity, the planets with initial mass <=1 M{sub J} and initial distance of about 0.1 AU could not survive. With the supposition of beta = 1.1, we find that the loss process has an effect on the planets with low mass at a {approx} 0.05 AU. In both cases, the effect of evaporation on massive planets can be neglected. Also, heating efficiency and initial eccentricity have significant influence on tidal evolution. We find that even low heating efficiency and initial eccentricity have a significant effect on tidal evolution. Our analysis shows that evaporation on planets with different initial masses can accelerate (decelerate) the tidal evolution due to the increase (decrease) in tide of the planet (star). Consequently, the effect of evaporation cannot be neglected in evolutionary calculations of close-in planets. The physical parameters of HD 209458b can be fitted by our model.

  3. Earth, Jupiter and Saturn as guides for extrasolar planets and brown dwarfs: a lightning climatology study

    NASA Astrophysics Data System (ADS)

    Hodosán, Gabriella; Asensio Torres, Rubén; Helling, Christiane; Vorgul, Irena

    2015-04-01

    Large-scale electrostatic discharges (i.e. lightning) have been observed in the Solar System. Apart from Earth there are direct detections from Jupiter and Saturn and indirect (only radio) detection from Uranus and Neptune. Recent observations made by the Venus Explorer revealed radio signals that may be related to lightning. Observations indicate that clouds form on extrasolar planets and brown dwarfs. The conditions in these clouds may be good for lightning to occur, which can be a main ionization process in these atmospheres (lightning in mineral clouds e.g.: Bailey et al. 2014, ApJ, 784, 43; Helling at al. 2013, ApJ, 767, 136; Helling et al. 2013, P&SS, 77, 152). In this study our aim is to compare lightning climatology from Earth, Jupiter and Saturn and use these statistics as a guide to study potential lightning on extrasolar planetary objects. Earth is a fair analogy for rocky or ocean planets while Jupiter and Saturn resemble giant planets and brown dwarfs. To give an estimate on the total lightning energy (or power) that can reach us from a particular extrasolar body, we need to know how much lightning can occur on the object globally. We will show the possibilities in the number and quality of the giant planet data sets, which may give a fine comparison of future observations of extrasolar giant gas planets and even brown dwarfs. Data were obtained from Lightning Imaging Sensor (LIS)/Optical Transient Detector (OTD) (e.g.: Cecil et al. 2014, Atmospheric Research, 135, 404), Sferics Timing and Ranging Network (STARNET) (e.g.: Morales Rodrigues et al. 2011, 2014, XIV and XV International Conference on Atmospheric Electricity) and World Wide Lightning Location Network (WWLLN) (e.g.: Hutchins et al. 2012, Radio Science, 47, RS6005), four major lightning detecting networks, which monitor lightning occurrence in the optical or radio range on Earth. We compare flash/stroke rates in space and time and use the data to refer to Earth as a transiting exoplanet. We

  4. Production of Star-Grazing and Star-Impacting Planetestimals via Orbital Migration of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Quillen, A. C.; Holman, M.

    2000-01-01

    During the orbital migration of a giant extrasolar planet via ejection of planetesimals (as studied by Murray et al. in 1998), inner mean-motion resonances can be strong enough to cause planetesimals to graze or impact the star. We integrate numerically the motions of particles which pass through the 3:1 or 4:1 mean-motion resonances of a migrating Jupiter-mass planet. We find that many particles can be trapped in the 3:1 or 4:1 resonances and pumped to high enough eccentricities that they impact the star. This implies that for a planet migrating a substantial fraction of its semimajor axis, a fraction of its mass in planetesimals could impact the star. This process may be capable of enriching the metallicity of the star at a time when the star is no longer fully convective. Upon close approaches to the star, the surfaces of these planetesimals will be sublimated. Orbital migration should cause continuing production of evaporating bodies, suggesting that this process should be detectable with searches for transient absorption lines in young stars. The remainder of the particles will not impact the star but can be ejected subsequently by the planet as it migrates further inward. This allows the planet to migrate a substantial fraction of its initial semimajor axis by ejecting planetesimals.

  5. Homogeneous Studies of Transiting Extrasolar Planets: Current Status and Future Plans

    NASA Astrophysics Data System (ADS)

    Taylor, John

    2011-09-01

    We now know of over 500 planets orbiting stars other than our Sun. The jewels in the crown are the transiting planets, for these are the only ones whose masses and radii are measurable. They are fundamental for our understanding of the formation, evolution, structure and atmospheric properties of extrasolar planets. However, their characterization is not straightforward, requiring extremely high-precision photometry and spectroscopy as well as input from theoretical stellar models. I summarize the motivation and current status of a project to measure the physical properties of all known transiting planetary systems using homogeneous techniques (Southworth 2008, 2009, 2010, 2011 in preparation). Careful attention is paid to the treatment of limb darkening, contaminating light, correlated noise, numerical integration, orbital eccentricity and orientation, systematic errors from theoretical stellar models, and empirical constraints. Complete error budgets are calculated for each system and can be used to determine which type of observation would be most useful for improving the parameter measurements. Known correlations between the orbital periods, masses, surface gravities, and equilibrium temperatures of transiting planets can be explored more safely due to the homogeneity of the properties. I give a sneak preview of Homogeneous Studies Paper 4, which includes the properties of thirty transiting planetary systems observed by the CoRoT, Kepler and Deep Impact space missions. Future opportunities are discussed, plus remaining problems with our understanding of transiting planets. I acknowledge funding from the UK STFC in the form of an Advanced Fellowship.

  6. The Presence of Methane in the Atmosphere of an Extrasolar Planet

    NASA Technical Reports Server (NTRS)

    Swain, Mark R.; Vasisht, Gautam; Tinetti, Giovanna

    2008-01-01

    Molecules present in the atmospheres of extrasolar planets are expected to influence strongly the balance of atmospheric radiation, to trace dynamical and chemical processes, and to indicate the presence of disequilibrium effects. As molecules have the potential to reveal atmospheric conditions and chemistry, searching for them is a high priority. The rotational-vibrational transition bands of water, carbon monoxide and methane are anticipated to be the primary sources of non-continuum opacity in hot-Jupiter planets. As these bands can overlap in wavelength, and the corresponding signatures from them are weak, decisive identification requires precision infrared spectroscopy. Here we report a near-infrared transmission spectrum of the planet HD 189733b that shows the presence of methane. Additionally, a resolved water vapour band at 1.9 (micro)m confirms the recent claim4 of water in this object. On thermochemical grounds, carbon monoxide is expected to be abundant in the upper atmosphere of hot-Jupiter planets, but is not identifiable here; therefore the detection of methane rather than carbon monoxide in such a hot planet could signal the presence of a horizontal chemical gradient away from the permanent dayside, or it may imply an ill-understood photochemical mechanism that leads to an enhancement of methane.

  7. ANALYSIS OF THE MOTION OF AN EXTRASOLAR PLANET IN A BINARY SYSTEM

    SciTech Connect

    Plávalová, Eva; Solovaya, Nina A. E-mail: solov@sai.msu.ru

    2013-11-01

    More than 10% of extra-solar planets (EPs) orbit in a binary or multiple stellar system. We investigated the motion of planets revolving in binary systems in the case of the three-body problem. We carried out an analysis of the motion of an EP revolving in a binary system with the following conditions: (1) a planet in a binary system revolves around one of the components (parent star); (2) the distance between the star's components is greater than that between the parent star and the orbiting planet (ratio of the semi-major axes is a small parameter); and (3) the mass of the planet is smaller than the mass of the stars, but is not negligible. The Hamiltonian of the system without short periodic terms was used. We expanded the Hamiltonian in terms of the Legendre polynomial and truncated after the second-order term, depending on only one angular variable. In this case, the solution of the system was obtained and the qualitative analysis of the motion was produced. We have applied this theory to real EPs and compared to the numerical integration. Analyses of the possible regions of motion are presented. It is shown that stable and unstable motions of EPs are possible. We applied our calculations to two binary systems hosting an EP and calculated the possible values for their unknown orbital elements.

  8. Tranistsearch: A Collaboration with Amateur Astronomers to Discover Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Castellano, T. P.

    2004-05-01

    The discovery of more than 100 planets around nearby solar-like stars that surpass Jupiter in size yet orbit their stars more quickly than Mercury has heralded a new era in astronomy. These enigmatic ``Hot-Jupiters" are large enough and close enough to their parent stars that their ``transits" can be captured by astronomers equipped with a small computer controlled telescope and a quality electronic CCD camera. The first known transiting extrasolar planet HD 209458b, in the constellation Pegasus, has been the subject of hundreds of scientific papers since its discovery in 1999. The transit of 8th magnitude HD 209458 has been observed by at least a dozen non-professional astronomers using telescopes as small as 4 inches in aperture. Using equipment already in hand, and armed with target lists, transit time predictions, observing techniques and software procedures developed by the transitsearch, collaboration non-professional astronomers can contribute significantly to the study of extrasolar planets by carefully measuring the brightness of stars with known Hot-Jupiters. In this way, amateur astronomers may resume, after a two century interruption, the tradition of planetary discoveries begun with William Herschel's 1787 discovery of the ``solar" planet Uranus. To date, transitsearch has amassed more than 50 interested observers in 10 states and 12 countries and provided research experience for undergraduate and graduate students from California, Washington, Michigan and North Carolina. A status report on the successes and challenges of a highly collaborative yet widely distributed project with participants of varying background and equipment levels will be discussed. Exciting upcoming opportunities for transitsearch observers to compete for time on NASA's SOFIA aircraft as outreach partners will be discussed and plans for this summer's observing campaign to expand our network of qualified observers through additional measurements of HD 209458b and hands-on workshops

  9. THE PROJECT: an Observatory / Transport Spaceship for Discovering and Populating Habitable Extrasolar Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Kilston, S.

    1998-12-01

    Recent extrasolar planet discoveries and related progress in astrophysics have refined our knowledge of the implications of the Drake equation. The Space Interferometry Mission and the planned Terrestrial Planet Finder will deepen this understanding, and begin pointing the way to places we need to explore at closer range. If the correct resolution of the Fermi paradox regarding intelligent extraterrestrials (``where are they?") is found to lie in the actual scarcity of such beings, it may turn out that we are more advanced than most other life-forms in our galaxy. In this case, a main purpose in finding planets may be to find places for us to go: astronomy will once again play a major role in human navigation and migration. We describe a strawman design concept for an astronomical observatory ship designed for launch beyond our solar system within several hundred years. This ship design would employ plausible physics, biology, technology, sociology, and economics to carry one million passengers in a one-G environment shielded from space radiation. A cruising speed under 0.01 c, slower than in many science-fiction concepts, minimizes power requirements and the danger from collisional impacts. The ship would contain all subsystems needed to sustain multi-generational life on a voyage of thousands of years, as well as the observatories to identify for human settlement a habitable extrasolar planet. Even the modestly advanced technology described here could spread intelligent life throughout our galaxy within 40 million years, a very small fraction of the galaxy's age. Motivation for such an ambitious project is three-fold: expanding our knowledge of the universe, enlisting the efforts and enthusiasms of humankind toward a very grand goal which will stimulate progress in all aspects of our cultures and technologies, and participating in the process of spreading life so its survivability and fruition are enhanced.

  10. The HARPS search for southern extra-solar planets. XX. Planets around the active star BD -08°2823

    NASA Astrophysics Data System (ADS)

    Hébrard, G.; Udry, S.; Lo Curto, G.; Robichon, N.; Naef, D.; Ehrenreich, D.; Benz, W.; Bouchy, F.; Lecavelier Des Etangs, A.; Lovis, C.; Mayor, M.; Moutou, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Ségransan, D.

    2010-03-01

    We report the detection of a planetary system around BD -08°2823 that includes at least one Uranus-mass planet and one Saturn-mass planet. This discovery serendipitously originates from a search for planetary transits in the Hipparcos photometry database. This program preferentially selected active stars and did not allow the detection of new transiting planets. It allowed however the identification of the K3V star BD -08°2823 as a target harboring a multiplanet system, which we secured and characterized thanks to an intensive monitoring with the HARPS spectrograph at the 3.6-m ESO telescope in La Silla. The stellar activity level of BD -08°2823 complicates the analysis but does not prohibit the detection of two planets around this star. BD -08°2823b has a minimum mass of 14.4±2.1 M⊕ and an orbital period of 5.60 days, whereas BD -08°2823c has a minimum mass of 0.33±0.03 MJup and an orbital period of 237.6 days. This new system strengthens the observation that low-mass planets are preferentially found in multiplanetary systems, but not around high-metallicity stars as is the case for massive planets. It also supports the belief that active stars should not be neglected in exoplanet searches even when searching for low-mass planets. Based on observations made with HARPS spectrograph on the 3.6-m ESO telescope at La Silla Observatory, Chile, under the programs ID 072.C-0488, 074.C-0364 and 078.C-0044. The full version of Table 1 (HARPS measurements of BD -08°2823) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/512/A46

  11. PLANETS AROUND LOW-MASS STARS (PALMS). II. A LOW-MASS COMPANION TO THE YOUNG M DWARF GJ 3629 SEPARATED BY 0.''2

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Tamura, Motohide

    2012-09-01

    We present the discovery of a 0.''2 companion to the young M dwarf GJ 3629 as part of our high-contrast adaptive optics imaging search for giant planets around low-mass stars with the Keck-II and Subaru telescopes. Two epochs of imaging confirm that the pair is comoving and reveal signs of orbital motion. The primary exhibits saturated X-ray emission which, together with its UV photometry from GALEX, points to an age younger than {approx}300 Myr. At these ages the companion lies below the hydrogen burning limit with a model-dependent mass of 46 {+-} 16 M{sub Jup} based on the system's photometric distance of 22 {+-} 3 pc. Resolved YJHK photometry of the pair indicates a spectral type of M7 {+-} 2 for GJ 3629 B. With a projected separation of 4.4 {+-} 0.6 AU and an estimated orbital period of 21 {+-} 5 yr, GJ 3629 AB is likely to yield a dynamical mass in the next several years, making it one of only a handful of brown dwarfs to have a measured mass and an age constrained from the stellar primary.

  12. 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.

  13. LOW-MASS PLANETS IN PROTOPLANETARY DISKS WITH NET VERTICAL MAGNETIC FIELDS: THE PLANETARY WAKE AND GAP OPENING

    SciTech Connect

    Zhu Zhaohuan; Stone, James M.; Rafikov, Roman R. E-mail: jstone@astro.princeton.edu

    2013-05-10

    Some regions in protoplanetary disks are turbulent, while some regions are quiescent (e.g. the dead zone). In order to study how planets open gaps in both inviscid hydrodynamic disk (e.g. the dead zone) and the disk subject to magnetorotational instability (MRI), we carried out both shearing box two-dimensional inviscid hydrodynamical simulations and three-dimensional unstratified magnetohydrodynamical (MHD) simulations (having net vertical magnetic fields) with a planet at the box center. We found that, due to the nonlinear wave steepening, even a low mass planet can open gaps in both cases, in contradiction to the ''thermal criterion'' for gap opening. In order to understand if we can represent the MRI turbulent stress with the viscous {alpha} prescription for studying gap opening, we compare gap properties in MRI-turbulent disks to those in viscous HD disks having the same stress, and found that the same mass planet opens a significantly deeper and wider gap in net vertical flux MHD disks than in viscous HD disks. This difference arises due to the efficient magnetic field transport into the gap region in MRI disks, leading to a larger effective {alpha} within the gap. Thus, across the gap, the Maxwell stress profile is smoother than the gap density profile, and a deeper gap is needed for the Maxwell stress gradient to balance the planetary torque density. Comparison with previous results from net toroidal flux/zero flux MHD simulations indicates that the magnetic field geometry plays an important role in the gap opening process. We also found that long-lived density features (termed zonal flows) produced by the MRI can affect planet migration. Overall, our results suggest that gaps can be commonly produced by low mass planets in realistic protoplanetary disks, and caution the use of a constant {alpha}-viscosity to model gaps in protoplanetary disks.

  14. 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.

  15. 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.

  16. 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.

  17. ABUNDANCES OF REFRACTORY ELEMENTS FOR G-TYPE STARS WITH EXTRASOLAR PLANETS

    SciTech Connect

    Kang, Wonseok; Lee, Sang-Gak; Kim, Kang-Min

    2011-08-01

    We confirm the difference in chemical abundance between stars with and without exoplanets and present the relation between chemical abundances and physical properties of exoplanets, such as planetary mass and the semimajor axis of planetary orbit. We obtained the spectra of 52 G-type stars from the Bohyunsan Optical Astronomy Observatory (BOAO) Echelle Spectrograph and carried out abundance analyses for 12 elements: Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni. We first found that the [Mn/Fe] ratios of planet-host stars are higher than those of comparison stars over the entire metallicity range, and we then found that in metal-poor stars of [Fe/H] < -0.4 the abundance difference was larger than in metal-rich samples, especially for the elements of Mg, Al, Sc, Ti, V, and Co. After examining the relation between planet properties and metallicities of planet-host stars, we observed that planet-host stars with low metallicities tend to have several low-mass planets (planet.

  18. Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars. II. Sulfur and Phosphorus

    NASA Astrophysics Data System (ADS)

    Visscher, Channon; Lodders, Katharina; Fegley, Bruce, Jr.

    2006-09-01

    Thermochemical equilibrium and kinetic calculations are used to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical behavior of individual S- and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. The results are independent of particular model atmospheres, and in principle, the equilibrium composition along the pressure-temperature profile of any object can be determined. Hydrogen sulfide (H2S) is the dominant S-bearing gas throughout substellar atmospheres and approximately represents the atmospheric sulfur inventory. Silicon sulfide (SiS) is a potential tracer of weather in substellar atmospheres. Disequilibrium abundances of phosphine (PH3) approximately representative of the total atmospheric phosphorus inventory are expected to be mixed upward into the observable atmospheres of giant planets and T dwarfs. In hotter objects, several P-bearing gases (e.g., P2, PH3, PH 2, PH, and HCP) become increasingly important at high temperatures.

  19. Cassini VIMS Spectra of the Earth from Saturn Orbit: an Extrasolar Planet Analog

    NASA Astrophysics Data System (ADS)

    Clark, Roger Nelson; Hedman, Matthew M.; Brown, Robert H.; Filacchione, Gianrico; Nicholson, Philip D.; Barnes, Jason W.

    2015-11-01

    Cassini VIMS has obtained spectra of the Earth while in Saturn orbit making observations of the Saturn system when the sun was behind Saturn. The observations, made in September 15, 2006 and July 19, 2013 are visible-near-infrared spectra (0.35 - 5.1 microns) of the Earth obtained at the furthest distance from the sun to date. The Earth was sub-pixel, 0.0088 milliradian in 2013 and 0.0085 milliradian in 2006, and the signal-to-noise ratio is low. A VIMS pixel IFOV is 0.25 x 0.5milliradian. As such, these data are likely representative of the first spectra that might be obtained of extrasolar terrestrial-like planets. What information can be derived from such remote observations? The observation made in 2013 had a phase angle of 97 degrees with multipleimage cubes providing a higher S/N average. The 2006 observation was made at a phase angle of 33 degrees but is a single cube, 1 pixel. The 2006 observation has Africa dominant on the disk, while the 2013 observation is mostly ocean with part of South America in sunlight. The 2013 visible data show clear signatures of Rayleigh scattering but this blue coloring can be from both the atmosphere and/or ocean. The 2006 data show a flatter spectrum, a signature of land. Both observations include the Moon in the field of view. The 0.35-2.5 micron spectral range shows significant absorption due to H2O liquid + gas. The thermal signature is very strong with the highest S/N of the entire spectrum. The best fit preliminary temperatures are 280 K with a small 380 K component (from the Moon), putting at least some of the planet in the goldilocks zone. There is strong absorption by CO2 at 4.25 microns in both 2013 and 2006 data. There is possible detection of chlorophyll and oxygen emission but higher S/N would be required for a positive detection. The spectral profile of the thermal emission could be used to constrain the diameter of the planet. If such spectra were obtained of an extrasolar planet, we could conclude that the

  20. ORBITAL MIGRATION OF INTERACTING LOW-MASS PLANETS IN EVOLUTIONARY RADIATIVE TURBULENT MODELS

    SciTech Connect

    Horn, Brandon; Mac Low, Mordecai-Mark; Lyra, Wladimir; Sandor, Zsolt E-mail: wlyra@amnh.org E-mail: zsolt.sandor@uibk.ac.at

    2012-05-01

    The torques exerted by a locally isothermal disk on an embedded planet lead to rapid inward migration. Recent work has shown that modeling the thermodynamics without the assumption of local isothermality reveals regions where the net torque on an embedded planet is positive, leading to outward migration of the planet. When a region with negative torque lies directly exterior to this, planets in the inner region migrate outward and planets in the outer region migrate inward, converging where the torque is zero. We incorporate the torques from an evolving non-isothermal disk into an N-body simulation to examine the behavior of planets or planetary embryos interacting in the convergence zone. We find that mutual interactions do not eject objects from the convergence zone. Small numbers of objects in a laminar disk settle into near resonant orbits that remain stable over the 10 Myr periods that we examine. However, either or both increasing the number of planets or including a correlated, stochastic force to represent turbulence drives orbit crossings and mergers in the convergence zone. These processes can build gas giant cores with masses of order 10 Earth masses from sub-Earth mass embryos in 2-3 Myr.

  1. RESOLVING THE sin(I) DEGENERACY IN LOW-MASS MULTI-PLANET SYSTEMS

    SciTech Connect

    Batygin, Konstantin; Laughlin, Gregory

    2011-04-01

    Long-term orbital evolution of multi-planet systems under tidal dissipation often converges to a stationary state, known as the tidal fixed point. The fixed point is characterized by a lack of oscillations in the eccentricities and apsidal alignment among the orbits. Quantitatively, the nature of the fixed point is dictated by mutual interactions among the planets as well as non-Keplerian effects. We show that if a roughly coplanar system hosts a hot, sub-Saturn mass planet, and is tidally relaxed, separation of planet-planet interactions and non-Keplerian effects in the equations of motion leads to a direct determination of the true masses of the planets. Consequently, a 'snap-shot' observational determination of the orbital state resolves the sin(I) degeneracy and opens up a direct avenue toward identification of the true lowest-mass exoplanets detected. We present an approximate, as well as a general, mathematical framework for computation of the line-of-sight inclination of secular systems, and apply our models illustratively to the 61 Vir system. We conclude by discussing the observability of planetary systems to which our method is applicable and we set our analysis into a broader context by presenting a current summary of the various possibilities for determining the physical properties of planets from observations of their orbital states.

  2. Thermal-orbital coupled tidal heating and habitability of Martian-sized extrasolar planets around M stars

    SciTech Connect

    Shoji, D.; Kurita, K.

    2014-07-01

    M-type stars are good targets in the search for habitable extrasolar planets. Due to their low effective temperatures, the habitable zone of M stars is very close to the stars themselves. For planets that are close to their stars, tidal heating plays an important role in thermal and orbital evolutions, especially when the planet's orbit has a relatively large eccentricity. Although tidal heating interacts with the thermal state and the orbit of the planet, such coupled calculations for extrasolar planets around M stars have not been conducted. We perform coupled calculations using simple structural and orbital models and analyze the thermal state and habitability of a terrestrial planet. Considering this planet to be Martian-sized, the tide heats up and partially melts the mantle, maintaining an equilibrium state if the mass of the star is less than 0.2 times the mass of the Sun and the initial eccentricity of the orbit is more than 0.2. The reduction of heat dissipation due to the melted mantle allows the planet to stay in the habitable zone for more than 10 Gyr even though the orbital distance is small. The surface heat flux at the equilibrium state is between that of Mars and Io. The thermal state of the planet mainly depends on the initial value of the eccentricity and the mass of the star.

  3. Constraints on planetary formation from the discovery & study of transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Triaud, A. H. M. J.

    2011-08-01

    After centuries of wondering about the presence of other worlds outside our Solar System, the first extrasolar planets were discovered about fifteen years ago. Since the quest continued. The greatest discovery of our new line of research, exoplanetology, has probably been the large diversity that those new worlds have brought forward; a diversity in mass, in size, in orbital periods, as well as in the architecture of the systems we discover. Planets very different from those composing our system have been detected. As such, we found hot Jupiters, gas giants which orbital period is only of a few days, mini-Neptunes, bodies five to ten time the mass of the Earth but covered by a thick gas layer, super-Earths of similar masses but rocky, lava worlds, and more recently, maybe the first ocean planet. Many more surprises probably await us. This thesis has for subject this very particular planet class: the hot Jupiters. Those astonishing worlds are still badly understood. Yet, thanks to the evolution of observational techniques and of the treatment of their signals, we probably have gathered as much knowledge from these worlds, than what was known of our own gas giants prior to their visit by probes. They are laboratories for a series of intense physical phenomena caused by their proximity to their star. Notably, these planets are found in average much larger than expected. In addition to these curiosities, their presence so close to their star is abnormal, the necessary conditions for the formation of such massive bodies, this close, not being plausible. Thus it is more reasonable to explain their current orbits by a formation far from their star, followed by an orbital migration. It is on this last subject that this thesis is on: the origin of hot Jupiters. The laws of physics are universal. Therefore, using the same physical phenomena, we need to explain the existence of hot Jupiters, while explaining why the Jupiter within our Solar System is found five times the

  4. 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.

  5. Optical and Near-UV Observations of the Transiting Extrasolar Planet TrES-4b

    NASA Astrophysics Data System (ADS)

    Smith, Carter-Thaxton; Turner, J.; Carleton, T.; Crawford, B.; Guvenen, B.; Hardegree-Ullman, K.; Small, L.; Towner, A. P.; Walker-LaFollette, A.; Henz, T.

    2013-01-01

    Using the Steward Observatory 61” Kuiper Telescope, The University of Arizona Astronomy Club conducted photometric observations of the transiting extrasolar planet TrES-4b as part of the Exoplanet Observation Project. Observations were made in the Bessell U, Harris B, and Harris R filters. Initial observations were made in 2009, with follow up observations in 2011. Basic data reduction and photometry was done using IRAF and determination of transit parameters was done using Transit Analysis Package (TAP) and JKTEBOP transit modeling code. We present an updated planetary mass, radius, density, surface gravity, Safronov number, equilibrium temperature, orbital distance, and orbital inclination for TrES-4b. In addition, we also searched for asymmetries between the near-UV and optical light curves. This project, started in spring 2009, has introduced many undergraduate students to research and given them valuable experience with data reduction and observation techniques.

  6. Detecting extra-solar planets with the Japanese 3.5 m SPICA space telescope

    NASA Astrophysics Data System (ADS)

    Abe, Lyu; Enya, Keigo; Tanaka, Shinichiro; Nakagawa, Takao; Kataza, Hirokazu; Tamura, Motohide; Guyon, Olivier

    2007-04-01

    We present the 3.5 m SPace Infrared telescope for Cosmology and Astrophysics (SPICA) space telescope, the launch of which is schedule around year 2015 by the Japanese HII-A rocket, and specifically discuss its use in the context of direct observation of extra-solar planets. This actively cooled (4.5 K), single aperture telescope will operate in the mid and far infrared spectral regions, and up to submillimetric wavelengths (200 μm). The lowest spectral region (5 to 20 μm), where the spatial resolution is the most favorable, will be dedicated to high contrast imaging with coronagraphy. This article describes the SPICA coronagraph project in terms of science, as well as our efforts to study a suitable instrumental concept, compatible with the constraints of the telescope architecture. To cite this article: L. Abe et al., C. R. Physique 8 (2007).

  7. FIVE LONG-PERIOD EXTRASOLAR PLANETS IN ECCENTRIC ORBITS FROM THE MAGELLAN PLANET SEARCH PROGRAM

    SciTech Connect

    Arriagada, Pamela; Minniti, Dante; Butler, R. Paul; Lopez-Morales, Mercedes; Boss, Alan P.; Chambers, John E.; Shectman, Stephen A.; Adams, Fred C.

    2010-03-10

    Five new planets orbiting G and K dwarfs have emerged from the Magellan velocity survey. These companions are Jovian-mass planets in eccentric (e >= 0.24) intermediate- and long-period orbits. HD 86226b orbits a solar metallicity G2 dwarf. The M{sub P} sin i mass of the planet is 1.5 M{sub JUP}, the semimajor axis is 2.6 AU, and the eccentricity is 0.73. HD 129445b orbits a metal-rich G6 dwarf. The minimum mass of the planet is M{sub P} sin i = 1.6 M{sub JUP}, the semimajor axis is 2.9 AU, and the eccentricity is 0.70. HD 164604b orbits a K2 dwarf. The M{sub P} sin i mass is 2.7 M{sub JUP}, the semimajor axis is 1.3 AU, and the eccentricity is 0.24. HD 175167b orbits a metal-rich G5 star. The M{sub P} sin i mass is 7.8 M{sub JUP}, the semimajor axis is 2.4 AU, and the eccentricity is 0.54. HD 152079b orbits a G6 dwarf. The M{sub P} sin i mass of the planet is 3 M{sub JUP}, the semimajor axis is 3.2 AU, and the eccentricity is 0.60.

  8. 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

  9. How the presence of a gas giant affects the formation of mean-motion resonances between two low-mass planets in a locally isothermal gaseous disc

    NASA Astrophysics Data System (ADS)

    Podlewska-Gaca, E.; Szuszkiewicz, E.

    2014-03-01

    In this paper we investigate the possibility of a migration-induced resonance locking in systems containing three planets, namely an Earth analogue (1 M⊕), a super-Earth (4 M⊕) and a gas giant (one Jupiter mass). The planets have been listed in order of increasing orbital periods. All three bodies are embedded in a locally isothermal gaseous disc and orbit around a solar mass star. We are interested in answering the following questions: will the low-mass planets form the same resonant structures with each other in the vicinity of the gas giant as in the case when the gas giant is absent? More in general, how will the presence of the gas giant affect the evolution of the two low-mass planets? When there is no gas giant in the system, it has been already shown that if the two low-mass planets undergo a convergent differential migration, they will capture each other in a mean-motion resonance. For the choices of disc parameters and planet masses made in this paper, the formation of the 5:4 resonance in the absence of the Jupiter has been observed in a previous investigation and confirmed here. In this work we add a gas giant on the most external orbit of the system in such a way that its differential migration is convergent with the low-mass planets. We show that the result of this set-up is the speeding up of the migration of the super-Earth and, after that, all three planets become locked in a triple mean-motion resonance. However, this resonance is not maintained due to the low-mass planet eccentricity excitation, a fact that leads to close encounters between planets and eventually to the ejection from the internal orbits of one or both low-mass planets. We have observed that the ejected low-mass planets can leave the system, fall into a star or become the external planet relative to the gas giant. In our simulations the latter situation has been observed for the super-Earth. It follows from the results presented here that the presence of a Jupiter-like planet

  10. Analysis of the Motion of the Extrasolar Planet HD 120136 Ab in a Binary System: Calculating Unknown Angular Orbital Elements

    NASA Astrophysics Data System (ADS)

    Plávalová, E.; Solovay, N. A.

    2015-07-01

    We have carried out an analysis of the motion of an extrasolar planet orbiting in a binary system, as a particular case of the three-body problem. The following assumptions have been made: a) the planet orbits around one of the binary components (the parent star); b) the distance between the stellar components is greater than that between the parent star and the orbiting planet (the ratio of the semi-major axes is a small parameter); c) the mass of the planet is smaller than the mass of the star, but is not negligible. We employed the Hamiltonian of the system without short-period terms, and we expanded it in terms of Legendre polynomials and truncated the expansion after the second-order terms. Such form of the Hamiltonian enables us to solve the differential equations of motion of our system and analyze of the motion of the extrasolar planet. We have applied this theory to the system HD 120136, and described the possible regions in which the planet can move. The theory permits us to calculate an unknown angular orbital element for the planet HD 120136 Ab, the ascending node: Ω1=134°±14°. The motion of the planet is expected to be stable over long time scales.

  11. Study of Extra-Solar Planets with the Advanced Fiber Optic Echelle

    NASA Technical Reports Server (NTRS)

    Noyes, Robert W.; Boyce, Joseph M. (Technical Monitor)

    2002-01-01

    This is the final report of NASA Grant NAG5-7505, for 'Study of Extra-solar Planets with the Advanced Fiber Optic Echelle'. This program was funded in response to our proposal submitted under NASA NRA 97-OSS-06, with a total period of performance from June 1, 1998 through Feb 28 2002. Principal Investigator is Robert W. Noyes; co-Investigators are Sylvain G. Korzennik (SAO), Peter Niserison (SAO), and Timothy M. Brown (High Altitude Observatory). Since the start of this program we have carried out more than 30 observing runs, typically of 5 to 7 days duration. We obtained a total of around 2000 usable observations of about 150 stars, where a typical observation consists of 3 exposures of 10 minutes each. Using this data base we detected thc two additional planetary companions to the star Upsilon Andromedae. This detection was made independently of, and essentially simultaneously with, a similar detection by the Berkeley group (Marcy et al): the fact that two data sets were completely independent and gave essentially the same orbital parameters for this three-planet system gave a strong confirmation of this important result. We also extended our previous detection of the planet orbiting Rho Coronae Borealis to get a better determination of its orbital eccentricity: e=0.13 +/- 0.05. We detected a new planet in orbit around the star HD 89744, with orbital period 256 days, semi-major axis 0.88 AU, eccentricity 0.70, and minimum mass m sini = 7.2 m(sub Jup). This discovery is significant because of the very high orbital eccentricity, arid also because HD 89744 has both high metallicity [Fe/H] and at the same time a low [C/Fe] abundance ratio.

  12. A CORRELATION BETWEEN HOST STAR ACTIVITY AND PLANET MASS FOR CLOSE-IN EXTRASOLAR PLANETS?

    SciTech Connect

    Poppenhaeger, K.; Schmitt, J. H. M. M.

    2011-07-01

    The activity levels of stars are influenced by several stellar properties, such as stellar rotation, spectral type, and the presence of stellar companions. Analogous to binaries, planetary companions are also thought to be able to cause higher activity levels in their host stars, although at lower levels. Especially in X-rays, such influences are hard to detect because coronae of cool stars exhibit a considerable amount of intrinsic variability. Recently, a correlation between the mass of close-in exoplanets and their host star's X-ray luminosity has been detected, based on archival X-ray data from the ROSAT All-Sky Survey. This finding has been interpreted as evidence for star-planet interactions. We show in our analysis that this correlation is caused by selection effects due to the flux limit of the X-ray data used and due to the intrinsic planet detectability of the radial velocity method, and thus does not trace possible planet-induced effects. We also show that the correlation is not present in a corresponding complete sample derived from combined XMM-Newton and ROSAT data.

  13. 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.

  14. Comparative Study on Hot Atom Coronae of Solar and Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Shematovich, Valery

    Solar/stellar forcing on the upper atmospheres of the solar and extrasolar planets via both absorption of the XUV (soft X-rays and extreme ultraviolet) radiation and atmospheric sputtering results in the formation of an extended neutral corona populated by the suprathermal (hot) H, C, N, and O atoms (see, e.g., Johnson et al., 2008). The hot corona, in turn, is altered by an inflow of the solar wind/magnetospheric plasma and local pick-up ions onto the planetary exosphere. Such inflow results in the formation of the superthermal atoms (energetic neutral atoms - ENAs) due to the charge exchange with the high-energy precipitating ions and can affect the long-term evolution of the atmosphere due to the atmospheric escape. The origin, kinetics and transport of the suprathermal H, C, N, and O atoms in the transition regions (from thermosphere to exosphere) of the planetary atmospheres are discussed. Reactions of dissociative recombination of the ionospheric ions CO _{2} (+) , CO (+) , O _{2} (+) , and N _{2} (+) with thermal electrons are the main photochemical sources of hot atoms. The dissociation of atmospheric molecules by the solar/stellar XUV radiation and accompanying photoelectron fluxes and the induced exothermic photochemistry are also the important sources of the suprathermal atoms. Such kinetic systems with the non-thermal processes are usually investigated with the different (test particles, DSMC, and hybrid) versions of the kinetic Monte Carlo method. In our studies the kinetic energy distribution functions of suprathermal and superthermal atoms were calculated using the stochastic model of the hot planetary corona (Shematovich, 2004, 2010; Groeller et al., 2014), and the Monte Carlo model (Shematovich et al., 2011, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere respectively. These functions allowed us to estimate the space distribution of suprathermals in the planetary transition regions. An application of these

  15. Diversity of planetary systems in low-mass disks. Terrestrial-type planet formation and water delivery

    NASA Astrophysics Data System (ADS)

    Ronco, M. P.; de Elía, G. C.

    2014-07-01

    Context. Several studies, observational and theoretical, suggest that planetary systems with only rocky planets are the most common in the Universe. Aims: We study the diversity of planetary systems that might form around Sun-like stars in low-mass disks without gas-giant planets. We focus especially on the formation process of terrestrial planets in the habitable zone (HZ) and analyze their water contents with the goal to determine systems of astrobiological interest. In addition, we study the formation of planets on wide orbits because they can be detected with the microlensing technique. Methods: N-body simulations of high resolution were developed for a wide range of surface density profiles. A bimodal distribution of planetesimals and planetary embryos with different physical and orbital configurations was used to simulate the planetary accretion process. The surface density profile combines a power law for the inside of the disk of the form r-γ, with an exponential decay to the outside. We performed simulations adopting a disk of 0.03 M⊙ and values of γ = 0.5, 1 and 1.5. Results: All our simulations form planets in the HZ with different masses and final water contents depending on the three different profiles. For γ = 0.5, our simulations produce three planets in the HZ with masses ranging from 0.03 M⊕ to 0.1 M⊕ and water contents between 0.2 and 16 Earth oceans (1 Earth ocean =2.8 × 10-4 M⊕). For γ = 1, three planets form in the HZ with masses between 0.18 M⊕ and 0.52 M⊕ and water contents from 34 to 167 Earth oceans. Finally, for γ = 1.5, we find four planets in the HZ with masses ranging from 0.66 M⊕ to 2.21 M⊕ and water contents between 192 and 2326 Earth oceans. This profile shows distinctive results because it is the only one of those studied here that leads to the formation of water worlds. Conclusions: Since planetary systems with γ = 1 and 1.5 present planets in the HZ with suitable masses to retain a long-lived atmosphere and

  16. Terrestrial planet formation in low-mass disks: dependence with initial conditions

    NASA Astrophysics Data System (ADS)

    Ronco, M. P.; de Elía, G. C.; Guilera, O. M.

    2014-07-01

    In general, most of the studies of terrestrial-type planet formation typically use ad hoc initial conditions. In this work we improved the initial conditions described in Ronco & de Elía (2014) starting with a semi-analytical model wich simulates the evolution of the protoplanetary disk during the gas phase. The results of the semi-analytical model are then used as initial conditions for the N-body simulations. We show that the planetary systems considered are not sensitive to the particular initial distribution of embryos and planetesimals and thus, the results are globally similar to those found in the previous work.

  17. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    PubMed

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  18. The HARPS search for southern extra-solar planets. XXXVI. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543

    NASA Astrophysics Data System (ADS)

    Astudillo-Defru, N.; Bonfils, X.; Delfosse, X.; Ségransan, D.; Forveille, T.; Bouchy, F.; Gillon, M.; Lovis, C.; Mayor, M.; Neves, V.; Pepe, F.; Perrier, C.; Queloz, D.; Rojo, P.; Santos, N. C.; Udry, S.

    2015-03-01

    Context. Planetary companions of a fixed mass induce reflex motions with a larger amplitude around lower-mass stars, which adds to making M dwarfs excellent targets for extra-solar planet searches. The most recent velocimeters with a stability of ~1 m s-1 can detect very low-mass planets out to the habitable zone of these stars. Low-mass small planets are abundant around M dwarfs, and most of the known potentially habitable planets orbit one of these cool stars. Aims: Our M-dwarf radial velocity monitoring with HARPS on the ESO 3.6 m telescope at La Silla observatory makes a major contribution to this sample. Methods: We present here dense radial velocity (RV) time series for three M dwarfs observed over ~five years: GJ 3293 (0.42 M⊙), GJ 3341 (0.47 M⊙), and GJ 3543 (0.45 M⊙). We extracted these RVs through minimum χ2-matching of each spectrum against a stack of all observed spectra for the same star that has a high signal-to-noise ratio. We then compared potential orbital signals against several stellar activity indicators to distinguish the Keplerian variations induced by planets from the spurious signals that result from rotational modulation of stellar surface inhomogeneities and from activity cycles. Results: Two Neptune-mass planets - msin(i) = 1.4 ± 0.1 and 1.3 ± 0.1Mnept - orbit GJ 3293 with periods P = 30.60 ± 0.02 d and P = 123.98 ± 0.38 d, possibly together with a super-Earth - msin(i) ~ 7.9 ± 1.4 M⊕ - with period P = 48.14 ± 0.12d. A super-Earth - msin(i) ~ 6.1 M⊕ - orbits GJ 3341 with P = 14.207 ± 0.007d. The RV variations of GJ 3543, on the other hand, reflect its stellar activity rather than planetary signals. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 072.C-0488, 082.C-0718 and 183.C-0437 at Cerro La Silla (Chile).Tables A.1-A.3 (radial velocity data) are available in electronic form at http://www.aanda.org and at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp

  19. Toward Direct Imaging of Low-mass Gas-Giant Planets with the James Webb Space Telescope

    NASA Astrophysics Data System (ADS)

    Schlieder, J. E.; Beichman, C. A.; Meyer, M. R.; Greene, T.

    2016-01-01

    In preparation for observations with the James Webb Space Telescope (JWST), we have identified new members of the nearby, young M dwarf sample and compiled an up to date list of these stars. Here we summarize our efforts to identify young M dwarfs, describe the current sample, and detail its demographics in the context of direct planet imaging. We also describe our investigations of the unprecedented sensitivity of the JWST when imaging nearby, young M dwarfs. The JWST is the only near term facility capable of routinely pushing direct imaging capabilities around M dwarfs to sub-Jovian masses and will provide key insight into questions regarding low-mass gas-giant properties, frequency, formation, and architectures.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  1. MINERVA-Red: A Census of Planets Orbiting the Nearest Low-mass Stars to the Sun

    NASA Astrophysics Data System (ADS)

    Blake, Cullen; Johnson, John; Plavchan, Peter; Sliski, David; Wittenmyer, Robert A.; Eastman, Jason D.; Barnes, Stuart

    2015-01-01

    Recent results from Kepler and ground-based exoplanet surveys suggest that low-mass stars host numerous small planets. Since low-mass stars are intrinsically faint at optical wavelengths, obtaining the Doppler precision necessary to detect these companions remains a challenge for existing instruments. We describe MINERVA-Red, a project to use a dedicated, robotic, near-infrared optimized 0.7 meter telescope and a specialized Doppler spectrometer to carry out an intensive, multi-year campaign designed to reveal the planetary systems orbiting some of the closest stars to the Sun. The MINERVA-Red cross-dispersed echelle spectrograph is optimized for the 'deep red', between 800 nm and 900 nm, where these stars are relatively bright. The instrument is very compact and designed for the ultimate in Doppler precision by using single-mode fiber input. We describe the spectrometer and the status of the MINERVA-Red project, which is expected to begin routine operations at Whipple Observatory on Mt Hopkins, Arizona, in 2015.

  2. EUV-driven ionospheres and electron transport on extrasolar giant planets orbiting active stars

    NASA Astrophysics Data System (ADS)

    Chadney, J. M.; Galand, M.; Koskinen, T. T.; Miller, S.; Sanz-Forcada, J.; Unruh, Y. C.; Yelle, R. V.

    2016-03-01

    The composition and structure of the upper atmospheres of extrasolar giant planets (EGPs) are affected by the high-energy spectrum of their host stars from soft X-rays to the extreme ultraviolet (EUV). This emission depends on the activity level of the star, which is primarily determined by its age. In this study, we focus upon EGPs orbiting K- and M-dwarf stars of different ages - ɛ Eridani, AD Leonis, AU Microscopii - and the Sun. X-ray and EUV (XUV) spectra for these stars are constructed using a coronal model. These spectra are used to drive both a thermospheric model and an ionospheric model, providing densities of neutral and ion species. Ionisation - as a result of stellar radiation deposition - is included through photo-ionisation and electron-impact processes. The former is calculated by solving the Lambert-Beer law, while the latter is calculated from a supra-thermal electron transport model. We find that EGP ionospheres at all orbital distances considered (0.1-1 AU) and around all stars selected are dominated by the long-lived H+ ion. In addition, planets with upper atmospheres where H2 is not substantially dissociated (at large orbital distances) have a layer in which H3+ is the major ion at the base of the ionosphere. For fast-rotating planets, densities of short-lived H3+ undergo significant diurnal variations, with the maximum value being driven by the stellar X-ray flux. In contrast, densities of longer-lived H+ show very little day/night variability and the magnitude is driven by the level of stellar EUV flux. The H3+ peak in EGPs with upper atmospheres where H2 is dissociated (orbiting close to their star) under strong stellar illumination is pushed to altitudes below the homopause, where this ion is likely to be destroyed through reactions with heavy species (e.g. hydrocarbons, water). The inclusion of secondary ionisation processes produces significantly enhanced ion and electron densities at altitudes below the main EUV ionisation peak, as

  3. Hydrogen Fluoride: an unexpected calalyst in the search for extra-solar planets

    NASA Astrophysics Data System (ADS)

    Walker, Gordon A.

    2014-01-01

    In the 1970s we developed low light level digital TV systems at UBC for the DAO 1.2-m telescope coudé spectrograph. John Glaspey eliminated reading-beam jitter using telluric water vapor lines as fiducials. Later, when we switched to solid state diode arrays, I suggested to Bruce Campbell that we could look for extra-solar planets using telluric lines to eliminate RV errors induced by irregular slit illumination. He went a step further by introducing a deployable absorption cell of hot HF gas. In December 1978 he and I demonstrated that an RV precision ~10 m/s was possible from observations of the Sun! Sufficient precision to detect the reflex acceleration of a solar-type star accompanied by a Jupiter. Bruce moved to CFHT in 1979 where the coudé spectrograph was a replica of that at DAO. He built an HF cell and gas handling system and we were granted some 6 to 8 nights per year. Modeling the line spread function proved critical in the reductions while, at the telescope, isolation of the telescope exit pupil and estimation of the epoch of the weighted mean exposure time were key. The program lasted some 12 years with, initially, little to show by way of results other than demonstrating the technique worked and so it attracted little interest but ample skepticism.

  4. Comments on the photometric method for the detection of extrasolar planets.

    NASA Astrophysics Data System (ADS)

    Giampapa, Mark S.; Craine, Eric R.; Hott, Douglas A.

    1995-11-01

    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 consideration of the characteristic time scales of forms of stellar activity compared to the time scale 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 developed 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.

  5. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  6. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    SciTech Connect

    Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

    2013-10-10

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10{sup –7}) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10{sup –6}-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H{sub 2}, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  7. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets. V. Alfvén Ionization

    NASA Astrophysics Data System (ADS)

    Stark, C. R.; Helling, Ch.; Diver, D. A.; Rimmer, P. B.

    2013-10-01

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (>=10-7) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10-6-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H2, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  8. The SOPHIE search for northern extrasolar planets. VII. A warm Neptune orbiting HD 164595

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    High-precision radial velocity surveys explore the population of low-mass exoplanets orbiting bright stars. This allows accurately deriving their orbital parameters such as their occurrence rate and the statistical distribution of their properties. Based on this, models of planetary formation and evolution can be constrained. The SOPHIE spectrograph has been continuously improved in past years, and thanks to an appropriate correction of systematic instrumental drift, it is now reaching 2 m s-1precision in radial velocity measurements on all timescales. As part of a dedicated radial velocity survey devoted to search for low-mass planets around a sample of 190 bright solar-type stars in the northern hemisphere, we report the detection of a warm Neptune with a minimum mass of 16.1 ± 2.7M⊕ orbiting the solar analog HD 164595 in 40 ± 0.24 days. We also revised the parameters of the multiplanetary system around HD 190360. We discuss this new detection in the context of the upcoming space mission CHEOPS, which is devoted to a transit search of bright stars harboring known exoplanets. Based on observations made with SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS/OSU Pythéas), France (program 07A.PNP.CONS).Appendix A is available in electronic form at http://www.aanda.org

  9. Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

    PubMed Central

    Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

    2011-01-01

    Abstract The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward

  10. Practicality of Using Oxygen Atom Emissions to Evaluate the Habitability of Extra-Solar Planets

    NASA Astrophysics Data System (ADS)

    Slanger, T. G.

    2005-12-01

    It has previously been proposed [Akasofu, 1999] that observation of the O(1S - 1D) green line from the atmospheres of extra-solar planets might be a marker for habitability. Guidance on this question is available within our own solar system. The green line is a dominant feature in the visible terrestrial nightglow, and the ultimate origin of its mesospheric emission is the three-body recombination of oxygen atoms. Until recently, it was believed that the green line was not a feature of the nightglows of the CO2 planets, Venus and Mars. It is now known that Venus at times shows green line emission with an intensity equal to terrestrial values [Slanger et al., 2001]. Furthermore, the intensity is quite variable, as is true for the much stronger O2( a-X) 1.27 μ emission. Recent observations of the Mars nightglow [Bertaux et al., 2005] give ambiguous results in the region of the O(1S-3P) line at 297.2 nm, but the same line in the dayglow is very strong, as evidenced in earlier Mariner results [Barth et al., 1971], and from the recent Mars Express data [F. Leblanc, private communication]. The O(1D-3P) 630 nm red line is a feature associated with Io, where dissociation of SO2 is a presumed source [Scherb et al., 1998]. Thus, observation of the oxygen green/red lines in the atmospheres of extrasolar planets provides insufficient information to reach conclusions about a habitable environment. Such detection would only indicate that there are oxygen-containing molecules present. Determination of an O2 column depth, by Fraunhofer A-band absorption, would be much more conclusive. Akasofu, S.-I., EOS, Transactions of the American Geophysical Union, 80, 397, 1999. Barth, C.A., C.W. Hord, J.B. Pearce, K.K. Kelly, G.P. Anderson, and A.I. Stewart, Mariner 6 and 7 Ultraviolet Spectrometer Experiment: Upper Atmosphere Data, Journal of Geophysical Research, 76, 2213-2227, 1971. Bertaux, J.-L., F. Leblanc, S. Perrier, E. Quemerais, O. Korablev, E. Dimarellis, A. Reberac, F. Forget, P

  11. Dynamics and Origin of Extra-solar Planetary Systems and Microlensing Detection of Extra-solar Planets

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    2003-01-01

    We compare a space-based microlensing search for planets, with a ground based microlensing search originally proposed by D. Tytler (Beichman, et al. 1996). Perturbations of microlensing light curves when the lens star has a planetary companion are sought by one wide angle survey telescope and an array of three or four followup narrow angle telescopes distributed in longitude that follow events with high precision, high time resolution photometry. Alternative ground based programs are considered briefly. With the four 2 meter telescopes distributed in longitude in the southern hemisphere in the Tytler proposal, observational constraints on a ground-based search for planets during microlensing events toward the center of the galaxy are severe. Probably less than 100 events could be monitored per year with high precision, high time resolution photometry with only about 42% coverage on the average regardless of how many events were discovered by the survey telescope. Statistics for the occurrence and properties for Jupiter-mass planets would be meaningful but relatively meager four years after the program was started, and meaningful statistics for Earth-mass planets would be non existent. In contrast, the 14,500 events in a proposed 4 year space based program (GEST = Galactic Exoplanet Survey Telescope) would yield very sound statistics on the occurrence, masses and separations of Jupiter-mass planets, and significant constraints on similar properties for Earth-mass planets. The significance of the Jupiter statistics would be to establish the frequency of planetary systems like our own, where terrestrial planets could exist inside the orbits of the giants.

  12. The HARPS search for Earth-like planets in the habitable zone. I. Very low-mass planets around HD 20794, HD 85512, and HD 192310

    NASA Astrophysics Data System (ADS)

    Pepe, F.; Lovis, C.; Ségransan, D.; Benz, W.; Bouchy, F.; Dumusque, X.; Mayor, M.; Queloz, D.; Santos, N. C.; Udry, S.

    2011-10-01

    Context. In 2009 we started an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars within the dedicated HARPS-Upgrade GTO program. Aims: The goal of this campaign is to gather very-precise radial-velocity data with high cadence and continuity to detect tiny signatures of very-low-mass stars that are potentially present in the habitable zone of their parent stars. Methods: Ten stars were selected among the most stable stars of the original HARPS high-precision program that are uniformly spread in hour angle, such that three to four of them are observable at any time of the year. For each star we recorded 50 data points spread over the observing season. The data points consist of three nightly observations with a total integration time of 10 min each and are separated by two hours. This is an observational strategy adopted to minimize stellar pulsation and granulation noise. Results: We present the first results of this ambitious program. The radial-velocity data and the orbital parameters of five new and one confirmed low-mass planets around the stars HD 20794, HD 85512, and HD 192310 are reported and discussed, among which is a system of three super-Earths and one that harbors a 3.6 M⊕-planet at the inner edge of the habitable zone. Conclusions: This result already confirms previous indications that low-mass planets seem to be very frequent around solar-type stars and that this may occur with a frequency higher than 30%. Based on observations made with the HARPS instrument on ESO's 3.6 m telescope at the La Silla Observatory in the frame of the HARPS-Upgrade GTO program ID 086.C-0230.Tables 7-9 (RV data) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/534/A58

  13. A statistical analysis of seeds and other high-contrast exoplanet surveys: massive planets or low-mass brown dwarfs?

    SciTech Connect

    Brandt, Timothy D.; Spiegel, David S.; McElwain, Michael W.; Grady, C. A.; Turner, Edwin L.; Mede, Kyle; Kuzuhara, Masayuki; Schlieder, Joshua E.; Brandner, W.; Feldt, M.; Wisniewski, John P.; Abe, L.; Biller, B.; Carson, J.; Currie, T.; Egner, S.; Golota, T.; Guyon, O.; Goto, M.; Hashimoto, J.; and others

    2014-10-20

    We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections (κ And b, two ∼60 M {sub J} brown dwarf companions in the Pleiades, PZ Tel B, and CD–35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ∼30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ∼5 M {sub J}, with a single power-law distribution. We find that p(M, a)∝M {sup –0.65} {sup ±} {sup 0.60} a {sup –0.85} {sup ±} {sup 0.39} (1σ errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M {sub J} companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.

  14. A Statistical Analysis of SEEDS and Other High-contrast Exoplanet Surveys: Massive Planets or Low-mass Brown Dwarfs?

    NASA Astrophysics Data System (ADS)

    Brandt, Timothy D.; McElwain, Michael W.; Turner, Edwin L.; Mede, Kyle; Spiegel, David S.; Kuzuhara, Masayuki; Schlieder, Joshua E.; Wisniewski, John P.; Abe, L.; Biller, B.; Brandner, W.; Carson, J.; Currie, T.; Egner, S.; Feldt, M.; Golota, T.; Goto, M.; Grady, C. A.; Guyon, O.; Hashimoto, J.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Henning, T.; Hodapp, K. W.; Inutsuka, S.; Ishii, M.; Iye, M.; Janson, M.; Kandori, R.; Knapp, G. R.; Kudo, T.; Kusakabe, N.; Kwon, J.; Matsuo, T.; Miyama, S.; Morino, J.-I.; Moro-Martín, A.; Nishimura, T.; Pyo, T.-S.; Serabyn, E.; Suto, H.; Suzuki, R.; Takami, M.; Takato, N.; Terada, H.; Thalmann, C.; Tomono, D.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.; Tamura, M.

    2014-10-01

    We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections (κ And b, two ~60 M J brown dwarf companions in the Pleiades, PZ Tel B, and CD-35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ~30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ~5 M J, with a single power-law distribution. We find that p(M, a)vpropM -0.65 ± 0.60 a -0.85 ± 0.39 (1σ errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M J companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  15. Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

    NASA Technical Reports Server (NTRS)

    Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy; Wellnitz, Dennis D.

    2011-01-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole disk Earth model simulations used to better under- stand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute s Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model (Tinetti et al., 2006a,b). This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of approx.100 pixels on the visible disk, and four categories of water clouds, which were defined using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to the Earth s lightcurve, absolute brightness, and spectral data, with a root-mean-square error of typically less than 3% for the multiwavelength lightcurves, and residuals of approx.10% for the absolute brightness throughout the visible and NIR spectral range. We extend our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of approx.7%, and temperature errors of less than 1K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated

  16. HATS-2b: A transiting extrasolar planet orbiting a K-type star showing starspot activity

    NASA Astrophysics Data System (ADS)

    Mohler-Fischer, M.; Mancini, L.; Hartman, J. D.; Bakos, G. Á.; Penev, K.; Bayliss, D.; Jordán, A.; Csubry, Z.; Zhou, G.; Rabus, M.; Nikolov, N.; Brahm, R.; Espinoza, N.; Buchhave, L. A.; Béky, B.; Suc, V.; Csák, B.; Henning, T.; Wright, D. J.; Tinney, C. G.; Addison, B. C.; Schmidt, B.; Noyes, R. W.; Papp, I.; Lázár, J.; Sári, P.; Conroy, P.

    2013-10-01

    We report the discovery of HATS-2b, the second transiting extrasolar planet detected by the HATSouth survey. HATS-2b is moving on a circular orbit around a V = 13.6 mag, K-type dwarf star (GSC 6665-00236), at a separation of 0.0230 ± 0.0003 AU and with a period of 1.3541 days. The planetary parameters have been robustly determined using a simultaneous fit of the HATSouth, MPG/ESO 2.2 m/GROND, Faulkes Telescope South/Spectral transit photometry, and MPG/ESO 2.2 m/FEROS, Euler 1.2 m/CORALIE, AAT 3.9 m/CYCLOPS radial-velocity measurements. HATS-2b has a mass of 1.37 ± 0.16 MJ, a radius of 1.14 ± 0.03 RJ, and an equilibrium temperature of 1567 ± 30 K. The host star has a mass of 0.88 ± 0.04 M⊙ and a radius of 0.89 ± 0.02 R⊙, and it shows starspot activity. We characterized the stellar activity by analyzing two photometric follow-up transit light curves taken with the GROND instrument, both obtained simultaneously in four optical bands (covering the wavelength range of 3860-9520 Å). The two light curves contain anomalies compatible with starspots on the photosphere of the host star along the same transit chord. Tables of the individual photometric measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A55

  17. Cloudless Atmospheres for L/T Dwarfs and Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Tremblin, P.; Amundsen, D. S.; Chabrier, G.; Baraffe, I.; Drummond, B.; Hinkley, S.; Mourier, P.; Venot, O.

    2016-02-01

    The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BDs) since their first detection 20 years ago has always been the key role played by micron-size condensates, called “dust” or “clouds,” in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this Letter, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near-infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution.

  18. Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

    NASA Astrophysics Data System (ADS)

    Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  19. Cloudless Atmospheres for L/T Dwarfs and Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Tremblin, P.; Amundsen, D. S.; Chabrier, G.; Baraffe, I.; Drummond, B.; Hinkley, S.; Mourier, P.; Venot, O.

    2016-01-01

    The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BDs) since their first detection 20 years ago has always been the key role played by micron-size condensates, called "dust" or "clouds," in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this Letter, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/ CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near-infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution.

  20. A Prototype Fringing Spectrograph for Sensitive Extra-solar Planet Searches and Astroseismology studies

    NASA Astrophysics Data System (ADS)

    Erskine, D.; Ge, J.

    1999-05-01

    We have developed a prototype fringing spectrograph optimized for sensitive stellar radial velocity measurements, aimed at detecting small extra-solar planet velocity perturbation and stellar seismology on an amplitude of ~ 1 m s(-1) or less. It is a combination of an angle-independent interferometer and a high throughput intermediate resolution spectrograph. The interferometer is used for measuring phase shifts caused by radial velocity variations of star light, while the spectrograph is applied for dispersing broad-band white fringes into different color channels to increase fringe visibility for precision phase measurements. A much simplified instrument response function (PSF), determined only by phase, amplitude and offset, compared to much more complicated ones in conventional echelle spectrographs, provides unprecedented sensitivity for radial velocity measurements. Preliminary lab-based experiments with this prototype instrument demonstrate 0.7 m s(-1) accuracy for short term radial velocity measurements. The zero point drift over 11 days was within 4 m s(-1) and may be due to the lack of interferometer stabilization during these runs. Stabilization is now being implemented through a close-loop electronics. This is expected to improve long term velocity measurement accuracy and make the instrument ready for first-light stellar observations. The instrument is also being tested with sunlight. The diurnal velocity variation caused by the Earth's rotation has been observed. Work to measure solar P-mode 5 minute oscillations is underway. This work is supported by the LLNL Laboratory Directed Research and Development (LDRD) grant through track 98-ERD-054.

  1. The UV limits of life on extrasolar planets: an experiment with halophile archaeabacteria at different UV doses.

    NASA Astrophysics Data System (ADS)

    Abrevaya, X. C.; Adamo, H. P.; Cortó N, E.; Mauas, P. J. D.

    Terrestial-type planets around M stars are proposed as feasible places for development of life as we know it. Nevertheless many dMe stars emit large amounts of UV radiation during flares and it is unknown if these events could be deleterious for life. Since terrestrial biological systems are particularly vulnerable to this kind of radiation, this fact could set a limit for habitability. Organisms as halophile archaeabacteria were found in ancient evaporites on Earth. Evaporites have been detected in Martian meteorites, so these organisms are proposed as plausible inhabitants of Mars-like planets or other extrasolar planets. We examine the effect of UV-C on the halophile archaea Natrialba magadii. Results show that these organisms are able to survive at the UV doses tested.

  2. 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

  3. Homogeneous studies of transiting extrasolar planets - IV. Thirty systems with space-based light curves

    NASA Astrophysics Data System (ADS)

    Southworth, John

    2011-11-01

    I calculate the physical properties of 32 transiting extrasolar planet and brown-dwarf systems from existing photometric observations and measured spectroscopic parameters. The systems studied include 15 observed by the CoRoT satellite, 10 by Kepler and five by the Deep Impact spacecraft. Inclusion of the objects studied in previous papers leads to a sample of 58 transiting systems with homogeneously measured properties. The Kepler data include observations from Quarter 2, and my analyses of several of the systems are the first to be based on short-cadence data from this satellite. The light curves are modelled using the JKTEBOP code, with attention paid to the treatment of limb darkening, contaminating light, orbital eccentricity, correlated noise and numerical integration over long exposure times. The physical properties are derived from the light-curve parameters, spectroscopic characteristics of the host star and constraints from five sets of theoretical stellar model predictions. An alternative approach using a calibration from eclipsing binary star systems is explored and found to give comparable results whilst imposing a much smaller computational burden. My results are in good agreement with published properties for most of the transiting systems, but discrepancies are identified for CoRoT-5, CoRoT-8, CoRoT-13, Kepler-5 and Kepler-7. Many of the error bars quoted in the literature are underestimated. Refined orbital ephemerides are given for CoRoT-8 and for the Kepler planets. Asteroseismic constraints on the density of the host stars are in good agreement with the photometric equivalents for HD 17156 and TrES-2, but not for HAT-P-7 and HAT-P-11. Complete error budgets are generated for each transiting system, allowing identification of the observations best-suited to improve measurements of their physical properties. Whilst most systems would benefit from further photometry and spectroscopy, HD 17156, HD 80606, HAT-P-7 and TrES-2 are now extremely well

  4. Comprehensive time series analysis of the transiting extrasolar planet WASP-33b

    NASA Astrophysics Data System (ADS)

    Kovács, G.; Kovács, T.; Hartman, J. D.; Bakos, G. Á.; Bieryla, A.; Latham, D.; Noyes, R. W.; Regály, Zs.; Esquerdo, G. A.

    2013-05-01

    Context. HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbor a transiting extrasolar planet (WASP-33b). The lack of high precision radial velocity (RV) data stresses the need for precise light curve analysis and gathering further RV data. Aims: By using available photometric and RV data, we perform a blend analysis, compute more accurate system parameters, confine the planetary mass, and, attempt to cast light on the observed transit anomalies. Methods: We combined the original HATNet observations and various followup data to jointly analyze the signal content and extract the transit component and used our RV data to aid the global parameter determination. Results: The blend analysis of the combination of multicolor light curves yields the first independent confirmation of the planetary nature of WASP-33b. We clearly identify three frequency components in the 15-21 d-1 regime with amplitudes 7-5 mmag. These frequencies correspond to the δ Scuti-type pulsation of the host star. None of these pulsation frequencies or their low-order linear combinations are in close resonance with the orbital frequency. We show that these pulsation components explain some but not all of the observed transit anomalies. The grand-averaged transit light curve shows that there is a ~1.5 mmag brightening shortly after the planet passes the mid-transit phase. Although the duration and amplitude of this brightening varies, it is visible even through the direct inspections of the individual transit events (some 40-60% of the followup light curves show this phenomenon). We suggest that the most likely explanation of this feature is the presence of a well-populated spot belt which is highly inclined to the orbital plane. This geometry is consistent with the inference from the spectroscopic anomalies. Finally, we constrain the planetary mass to Mp = 3.27 ± 0.73 MJ by using our RV data collected by the TRES spectrograph. Appendix A is available in electronic form at http

  5. The first high-precision radial velocity search for extra-solar planets

    NASA Astrophysics Data System (ADS)

    Walker, Gordon A. H.

    2012-01-01

    The reflex motion of a star induced by a planetary companion is too small to detect by photographic astrometry. The apparent discovery in the 1960s of planetary systems around certain nearby stars, in particular Barnard's star, turned out to be spurious. Conventional stellar radial velocities determined from photographic spectra at that time were also too inaccurate to detect the expected reflex velocity changes. In the late 1970s and early 1980s, the introduction of solid-state, signal-generating detectors and absorption cells to impose wavelength fiducials directly on the starlight, reduced radial velocity errors to the point where such a search became feasible. Beginning in 1980, our team from UBC introduced an absorption cell of hydrogen fluoride gas in front of the CFHT coudé spectrograph and, for 12 years, monitored the radial velocities of some 29 solar-type stars. Since it was assumed that extra-solar planets would most likely resemble Jupiter in mass and orbit, we were awarded only three or four two-night observing runs each year. Our survey highlighted three potential planet hosting stars, γ Cep (K1 IV), β Gem (K0 III), and ɛ Eri (K2 V). The putative planets all resembled Jovian systems with periods and masses of: 2.5 years and 1.4 MJ, 1.6 years and 2.6 MJ, and 6.9 years and 0.9 MJ, respectively. All three were subsequently confirmed from more extensive data by the Texas group led by Cochran and Hatzes who also derived the currently accepted orbital elements. None of these three systems is simple. All five giant stars and the supergiant in our survey proved to be intrinsic velocity variables. When we first drew attention to a possible planetary companion to γ Cep in 1988 it was classified as a giant, and there was the possibility that its radial velocity variations and those of β Gem (K0 III) were intrinsic to the stars. A further complication for γ Cep was the presence of an unseen secondary star in an orbit with a period initially estimated at

  6. HAT-P-15b: A 10.9 DAY EXTRASOLAR PLANET TRANSITING A SOLAR-TYPE STAR

    SciTech Connect

    Kovacs, G.; Bakos, G. A.; Hartman, J. D.; Torres, G.; Noyes, R. W.; Latham, D. W.; Sasselov, D. D.; Stefanik, R. P.; Esquerdo, G. A.; Fernandez, J. M.; Howard, A. W.; Marcy, G. W.; Isaacson, H.; Fischer, D. A.; Johnson, J. A.; Lazar, B. Beky J.; Papp, I.; Sari, P.

    2010-12-01

    We report the discovery of HAT-P-15b, a transiting extrasolar planet in the 'period valley', a relatively sparsely populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V= 12.16. It has a mass of 1.01 {+-} 0.04 M{sub sun}, radius of 1.08 {+-} 0.04 R{sub sun}, effective temperature 5568 {+-} 90 K, and metallicity [Fe/H] = +0.22 {+-} 0.08. The planetary companion orbits the star with a period P = 10.863502 {+-} 0.000027 days, transit epoch T{sub c} = 2454638.56019 {+-} 0.00048 (BJD), and transit duration 0.2285 {+-} 0.0015 days. It has a mass of 1.946 {+-} 0.066 M{sub J} and radius of 1.072 {+-} 0.043 R{sub J} yielding a mean density of 1.96 {+-} 0.22 g cm{sup -3}. At an age of 6.8{sup +2.5}{sub -1.6} Gyr, the planet is H/He-dominated and theoretical models require about 2% (10 M{sub +}) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of {approx}820 K during transit, and {approx}1000 K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy.

  7. Challenges of Using Earth's Atmosphere as a Proxy for Detecting Biosignatures on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    DeMarines, J.

    2012-06-01

    Assessing the challenges associated with the detectability of primitive biosignatures present on early Earth (methane and ethane) and addressing the observational difficulties when we begin to observe extrasolar atmospheres with a TPF-O mission.

  8. A Large Sparse Aperture Densified Pupil Hypertelescope Concept for Ground Based Detection of Extra-Solar Earth-Like Planets

    NASA Technical Reports Server (NTRS)

    Gezari, D.; Lyon, R.; Woodruff, R.; Labeyrie, A.; Oegerle, William (Technical Monitor)

    2002-01-01

    A concept is presented for a large (10 - 30 meter) sparse aperture hyper telescope to image extrasolar earth-like planets from the ground in the presence of atmospheric seeing. The telescope achieves high dynamic range very close to bright stellar sources with good image quality using pupil densification techniques. Active correction of the perturbed wavefront is simplified by using 36 small flat mirrors arranged in a parabolic steerable array structure, eliminating the need for large delat lines and operating at near-infrared (1 - 3 Micron) wavelengths with flats comparable in size to the seeing cells.

  9. The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE

    NASA Astrophysics Data System (ADS)

    Naef, D.; Mayor, M.; Beuzit, J. L.; Perrier, C.; Queloz, D.; Sivan, J. P.; Udry, S.

    2004-01-01

    We present our ELODIE radial-velocity measurements of HD 74156 and 14 Her (HD 145675). These stars exhibit low-amplitude radial-velocity variations induced by the presence of low-mass companions. The radial-velocity data of HD 74156 reveal the presence of two planetary companions: a 1.86 MJup planet on a 51.64-d orbit and a 6.2 MJup planet on a long-period (≃5.5 yr) orbit. Both orbits are fairly eccentric (e = 0.64 and 0.58). The 4.7 MJup companion to 14 Her has a long period (4.9 yr) and a moderately eccentric orbit (e = 0.34). We detect an additional linear radial-velocity trend superimposed on the periodic signal for this star. We also compute updated orbital solutions for HD 209458 and 51 Peg (HD 217014). Finally, we present our ELODIE radial-velocity data and orbital solutions for 5 stars known to host planetary companions: Ups And (HD 9826), 55 Cnc (HD 75732), 47 UMa (HD 95128), 70 Vir (HD 117176) and HD 187123. We confirm the previously published orbital solutions for Ups And, 70 Vir and HD 187123. Our data are not sufficient to fully confirm the orbital solutions for 55 Cnc and 47 UMa. Based on observations made with the ELODIE echelle spectrograph mounted on the 1.93-m Telescope at the Observatoire de Haute-Provence (CNRS) and with the CORALIE echelle spectrograph mounted on the 1.2-m Euler Swiss Telescope at ESO-La Silla Observatory. The ELODIE and CORALIE measurements discussed in this paper are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/414/351

  10. The HARPS search for southern extra-solar planets. XL. Searching for Neptunes around metal-poor stars

    NASA Astrophysics Data System (ADS)

    Faria, J. P.; Santos, N. C.; Figueira, P.; Mortier, A.; Dumusque, X.; Boisse, I.; Lo Curto, G.; Lovis, C.; Mayor, M.; Melo, C.; Pepe, F.; Queloz, D.; Santerne, A.; Ségransan, D.; Sousa, S. G.; Sozzetti, A.; Udry, S.

    2016-05-01

    Context. As a probe of the metallicity of proto-planetary disks, stellar metallicity is an important ingredient for giant planet formation, most likely through its effect on the timescales in which rocky or icy planet cores can form. Giant planets have been found to be more frequent around metal-rich stars, in agreement with predictions based on the core-accretion theory. In the metal-poor regime, however, the frequency of planets, especially low-mass planets, and the way it depends on metallicity are still largely unknown. Aims: As part of a planet search programme focused on metal-poor stars, we study the targets from this survey that were observed with HARPS on more than 75 nights. The main goals are to assess the presence of low-mass planets and provide a first estimate of the frequency of Neptunes and super-Earths around metal-poor stars. Methods: We performed a systematic search for planetary companions, both by analysing the periodograms of the radial-velocities and by comparing, in a statistically meaningful way, models with an increasing number of Keplerians. Results: A first constraint on the frequency of planets in our metal-poor sample is calculated considering the previous detection (in our sample) of a Neptune-sized planet around HD 175607 and one candidate planet (with an orbital period of 68.42 d and minimum mass Mpsini = 11.14 ± 2.47 M⊕) for HD 87838, announced in the present study. This frequency is determined to be close to 13% and is compared with results for solar-metallicity stars. Based on observations collected at ESO facilities under programs 082.C-0212, 085.C-0063, 086.C-0284, and 190.C-0027 (with the HARPS spectrograph at the ESO 3.6-m telescope, La Silla-Paranal Observatory).

  11. Searching for extra-solar planets and probing the atmosphere of Bulge giant stars through gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Cassan, Arnaud

    2005-12-01

    A galactic microlensing effect occurs when a luminous object (the source) located in the Bulge of the Milky Way is temporarily magnified by an intervening star (the "microlens'') passing close to its line of sight. This phenomenom is used for searching extra-solar planets and constraining their abundance, as well as probing the atmosphere of Bulge giant stars. The PLANET collaboration (Probing Lensing Anomalies NETwork) monitors carefully chosen ongoing microlensing events on a round-the-clock basis from observatories in the southern hemisphere. Mathematical and numerical methods are developed to deal with both the highly non-linear equations and the wide parameter space plagued with many local minima. Microlensing exoplanet detection is possible because planets can induce perturbations to the standard lensing light curves. Its sensitivity can go down to Earth-mass planets, thanks to gravitational caustics that arise from a binary lens. If crossed by the source, additional secondary magnification peaks in the light curve can occur. OGLE 2005-BLG-390Lb is the third extra-solar planet detected by this method so far, and its discovery is reported here. It is the lightest exoplanet to date - about five Earth masses - located at a rather large distance of its star, that is about three astronomical units. A selection of microlensing events monitored during the 1995-2004 period was used to derive limits on exoplanets abundance around red dwarf stars. The method is described and detection efficiency diagrams are provided as a basis of the statistical analysis. Last, a differential magnification effect over the disk of the source star is used as a tool to probe Bulge giants stellar atmospheres. Limb-darkening parameters of a set of stars have been measured and compared to atmosphere models. Moreover, a high-resolution spectroscopic monitoring of a Bulge G5III giant at 9 kpc made possible both the measurement of the individual lines equivalent width and the direct detection

  12. A UNIFORM ANALYSIS OF 118 STARS WITH HIGH-CONTRAST IMAGING: LONG-PERIOD EXTRASOLAR GIANT PLANETS ARE RARE AROUND SUN-LIKE STARS

    SciTech Connect

    Nielsen, Eric L.; Close, Laird M.

    2010-07-10

    We expand on the results of Nielsen et al., using the null result for giant extrasolar planets around the 118 target stars from the Very Large Telescope (VLT) NACO H- and Ks-band planet search (conducted by Masciadri and collaborators in 2003 and 2004), the VLT and MMT Simultaneous Differential Imager survey, and the Gemini Deep Planet Survey to set constraints on the population of giant extrasolar planets. Our analysis is extended to include the planet luminosity models of Fortney et al., as well as the correlation between stellar mass and frequency of giant planets found by Johnson et al. Doubling the sample size of FGKM stars strengthens our conclusions: a model for extrasolar giant planets with power laws for mass and semimajor axis as given by Cumming et al. cannot, with 95% confidence, have planets beyond 65 AU, compared to the value of 94 AU reported by Nielsen et al., using the models of Baraffe et al. When the Johnson et al. correction for stellar mass (which gives fewer Jupiter-mass companions to M stars with respect to solar-type stars) is applied, however, this limit moves out to 82 AU. For the relatively new Fortney et al. models, which predict fainter planets across most of parameter space, these upper limits, with and without a correction for stellar mass, are 182 and 234 AU, respectively.

  13. 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.

  14. NEAR-INFRARED SPECTROSCOPY OF THE EXTRASOLAR PLANET HR 8799 b

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Dupuy, Trent J.; Cushing, Michael C.

    2010-11-01

    We present 2.12-2.23 {mu}m high contrast integral field spectroscopy of the extrasolar planet HR 8799 b. Our observations were obtained with OSIRIS on the Keck II telescope and sample the 2.2 {mu}m CH{sub 4} feature, which is useful for spectral classification and as a temperature diagnostic for ultracool objects. The spectrum of HR 8799 b is relatively featureless, with little or no methane absorption, and does not exhibit the strong CH{sub 4} seen in T dwarfs of similar absolute magnitudes. The spectrum is consistent with field objects from early-L to T4 (3{sigma} confidence level), with a best-fitting type of T2. A similar analysis of the published 1-4 {mu}m photometry shows the infrared spectral energy distribution (SED) matches L5-L8 field dwarfs, especially the reddest known objects which are believed to be young and/or very dusty. Overall, we find that HR 8799 b has a spectral type consistent with L5-T2, although its SED is atypical compared to most field objects. We fit the 2.2 {mu}m spectrum and the infrared SED using the Hubeny and Burrows, Burrows et al., and Ames-Dusty model atmosphere grids, which incorporate non-equilibrium chemistry, non-solar metallicities, and clear and cloudy variants. No models agree with all of the data, but those with intermediate clouds produce significantly better fits. The largest discrepancy occurs in the J band, which is highly suppressed in HR 8799 b. Models with high eddy diffusion coefficients and high metallicities are somewhat preferred over those with equilibrium chemistry and solar metallicity. The best-fitting effective temperatures range from 1300 to 1700 K with radii between {approx}0.3 and 0.5 R{sub Jup}. These values are inconsistent with evolutionary model-derived values of 800-900 K and 1.1-1.3 R{sub Jup} based on the luminosity of HR 8799 b and the age of HR 8799, a discrepancy that probably results from imperfect atmospheric models or the limited range of physical parameters covered by the models. The low

  15. Greenhouse Warming on Early Mars and Extrasolar Planets plus a Critique of the Martian Valley Impact Hypothesis

    NASA Astrophysics Data System (ADS)

    Ramirez, R. M.; Kasting, J. F.

    2011-12-01

    Previous studies have suggested dense CO2-rich atmospheres as warming agents for early Mars and on extrasolar planets. For Mars, 1-D climate models have been unable to explain how global mean surface temperatures could have remained above the freezing point of water. After making several model updates, it is demonstrated that even those results were overly optimistic. The addition of methane produces only a very modest greenhouse effect (~2.5K). So, the best greenhouse warming mechanism for warming early Mars is probably CO2 clouds, as suggested by previous investigators. Despite the difficulties in explaining how early Mars could have been warm, it is shown that leading cold dry Mars hypotheses are untenable. For extrasolar planets, the most interesting question has been the habitability of Gliese 581d. Whereas some 1-D models suggest that a dense CO2-rich atmosphere could keep the mean surface temperature of this planet above freezing, other authors have argued that these same models may overestimate the greenhouse effect of CO2. In agreement with calculations by other investigators, surface temperatures above the freezing point of water are predicted for Gliese 581d, albeit at a very high surface pressure (18 bar). Adding methane only makes the atmosphere cooler because its anti-greenhouse effect is quite pronounced for planets around M stars. The addition of 0.3% CH4 resulted in a surface temperature change of -10 degrees. Conversely, adding 1% CH4 around an F star produced 20K of warming. Clearly, the climatic effect of different infrared-active gases is dependent on spectral class.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  17. WASP-44b, WASP-45b and WASP-46b: three short-period, transiting extrasolar planets

    NASA Astrophysics Data System (ADS)

    Anderson, D. R.; Collier Cameron, A.; Gillon, M.; Hellier, C.; Jehin, E.; Lendl, M.; Maxted, P. F. L.; Queloz, D.; Smalley, B.; Smith, A. M. S.; Triaud, A. H. M. J.; West, R. G.; Pepe, F.; Pollacco, D.; Ségransan, D.; Todd, I.; Udry, S.

    2012-05-01

    We report the discovery of three extrasolar planets that transit their moderately bright (mV= 12-13) host stars. WASP-44b is a 0.89-MJup planet in a 2.42-day orbit around a G8V star. WASP-45b is a 1.03-MJup planet which passes in front of the limb of its K2V host star every 3.13 days. Weak Ca II H&K emission seen in the spectra of WASP-45 suggests that the star is chromospherically active. WASP-46b is a 2.10-MJup planet in a 1.43-day orbit around a G6V star. Rotational modulation of the light curves of WASP-46 and weak Ca II H&K emission in its spectra show the star to be photospherically and chromospherically active. We imposed circular orbits in our analyses as the radial-velocity data are consistent with (near-)circular orbits, as could be expected from both empirical and tidal-theory perspectives for such short-period, ˜Jupiter-mass planets. We discuss the impact of fitting for eccentric orbits for such planets when not supported by the data. The derived planetary and stellar radii depend on the fitted eccentricity and these parameters inform intense theoretical efforts concerning tidal circularization and heating, bulk planetary composition and the observed systematic errors in planetary and stellar radii. As such, we recommend exercising caution in fitting the orbits of short-period, ˜Jupiter-mass planets with an eccentric model when there is no evidence of non-circularity.

  18. IBIS: An Interferometer-Based Imaging System for Detecting Extrasolar Planets with a Next Generation Space Telescope

    NASA Technical Reports Server (NTRS)

    Diner, David J.

    1989-01-01

    The direct detection of extrasolar planetary systems is a challenging observational objective. The observing system must be able to detect faint planetary signals against the background of diffracted and scattered starlight, zodiacal light, and in the IR, mirror thermal radiation. As part of a JPL study, we concluded that the best long-term approach is a 10-20 m filled-aperture telescope operating in the thermal IR (10-15 microns). At these wavelengths, the star/planet flux ratio is on the order of 10(exp 6)-10(exp 8). Our study supports the work of Angel et al., who proposed a cooled 16-m IR telescope and a special apodization mask to suppress the stellar light within a limited angular region around the star. Our scheme differs in that it is capable of stellar suppression over a much broader field-of- view, enabling more efficient planet searches. To do this, certain key optical signal-processing components are needed, including a coronagraph to apodize the stellar diffraction pattern, an infrared interferometer to provide further starlight suppression, a complementary visible-wavelength interferometer to sense figure errors in the telescope optics, and a deformable mirror to adaptively compensate for these errors. Because of the central role of interferometry we have designated this concept the Interferometer-Based Imaging System (IBIS). IBIS incorporates techniques originally suggested by Ken Knight for extrasolar planet detection at visible wavelengths. The type of telescope discussed at this workshop is well suited to implementation of the IBIS concept.

  19. Near-infrared Spectroscopy of the Extrasolar Planet HR 8799 b

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Dupuy, Trent J.; Cushing, Michael C.

    2010-11-01

    We present 2.12-2.23 μm high contrast integral field spectroscopy of the extrasolar planet HR 8799 b. Our observations were obtained with OSIRIS on the Keck II telescope and sample the 2.2 μm CH4 feature, which is useful for spectral classification and as a temperature diagnostic for ultracool objects. The spectrum of HR 8799 b is relatively featureless, with little or no methane absorption, and does not exhibit the strong CH4 seen in T dwarfs of similar absolute magnitudes. The spectrum is consistent with field objects from early-L to T4 (3σ confidence level), with a best-fitting type of T2. A similar analysis of the published 1-4 μm photometry shows the infrared spectral energy distribution (SED) matches L5-L8 field dwarfs, especially the reddest known objects which are believed to be young and/or very dusty. Overall, we find that HR 8799 b has a spectral type consistent with L5-T2, although its SED is atypical compared to most field objects. We fit the 2.2 μm spectrum and the infrared SED using the Hubeny & Burrows, Burrows et al., and Ames-Dusty model atmosphere grids, which incorporate non-equilibrium chemistry, non-solar metallicities, and clear and cloudy variants. No models agree with all of the data, but those with intermediate clouds produce significantly better fits. The largest discrepancy occurs in the J band, which is highly suppressed in HR 8799 b. Models with high eddy diffusion coefficients and high metallicities are somewhat preferred over those with equilibrium chemistry and solar metallicity. The best-fitting effective temperatures range from 1300 to 1700 K with radii between ~0.3 and 0.5 R Jup. These values are inconsistent with evolutionary model-derived values of 800-900 K and 1.1-1.3 R Jup based on the luminosity of HR 8799 b and the age of HR 8799, a discrepancy that probably results from imperfect atmospheric models or the limited range of physical parameters covered by the models. The low temperature inferred from evolutionary models

  20. Predicting Precession Rates from Secular Dynamics for Extra-solar Multi-planet Systems

    NASA Astrophysics Data System (ADS)

    Van Laerhoven, Christa

    2015-12-01

    Considering the secular dynamics of multi-planet systems provides substantial insight into the interactions between planets in those systems. Secular interactions are those that don't involve knowing where a planet is along its orbit, and they dominate when planets are not involved in mean motion resonances. These interactions exchange angular momentum among the planets, evolving their eccentricities and inclinations. To second order in the planets' eccentricities and inclinations, the eccentricity and inclination perturbations are decoupled. Given the right variable choice, the relevant differential equations are linear and thus the eccentricity and inclination behaviors can be described as a sum of eigenmodes. Since the underlying structure of the secular eigenmodes can be calculated using only the planets' masses and semi-major axes, one can elucidate the eccentricity and inclination behavior of planets in exoplanet systems even without knowing the planets' current eccentricities and inclinations. I have calculated both the eccentricity and inclination secular eigenmodes for the population of known multi-planet systems whose planets have well determined masses and periods and have used this to predict what range of pericenter precession (and nodal regression) rates the planets may have. One might have assumed that in any given system the planets with shorter periods would have faster precession rates, but I show that this is not necessarily the case. Planets that are 'loners' have narrow ranges of possible precession rates, while planets that are 'groupies' can have a wider range of possible precession rates. Several planets are expected to undergo significant precession on few-year timescales and many planets (though not the majority of planets) will undergo significant precession on decade timescales.

  1. HAT-P-20b-HAT-P-23b: FOUR MASSIVE TRANSITING EXTRASOLAR PLANETS

    SciTech Connect

    Bakos, G. A.; Hartman, J.; Torres, G.; Latham, D. W.; Noyes, R. W.; Kipping, D.; Esquerdo, G. A.; Beky, B.; Perumpilly, G.; Everett, M.; Sasselov, D. D.; Stefanik, R. P.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Shporer, A.; Buchhave, L. A.; Lazar, J.; and others

    2011-12-01

    We report the discovery of four relatively massive (2-7 M{sub J}) transiting extrasolar planets. HAT-P-20b orbits the moderately bright V = 11.339 K3 dwarf star GSC 1910-00239 on a circular orbit, with a period P = 2.875317 {+-} 0.000004 days, transit epoch T{sub c} = 2455080.92661 {+-} 0.00021 (BJD{sub UTC}), and transit duration 0.0770 {+-} 0.0008 days. The host star has a mass of 0.76 {+-} 0.03 M{sub Sun }, radius of 0.69 {+-} 0.02 R{sub Sun }, effective temperature 4595 {+-} 80 K, and metallicity [Fe/H] = +0.35 {+-} 0.08. The planetary companion has a mass of 7.246 {+-} 0.187 M{sub J} and a radius of 0.867 {+-} 0.033 R{sub J} yielding a mean density of 13.78 {+-} 1.50 g cm{sup -3}. HAT-P-21b orbits the V = 11.685 G3 dwarf star GSC 3013-01229 on an eccentric (e = 0.228 {+-} 0.016) orbit, with a period P = 4.124481 {+-} 0.000007 days, transit epoch T{sub c} = 2454996.41312 {+-} 0.00069, and transit duration 0.1530 {+-} 0.0027 days. The host star has a mass of 0.95 {+-} 0.04 M{sub Sun }, radius of 1.10 {+-} 0.08 R{sub Sun }, effective temperature 5588 {+-} 80 K, and metallicity [Fe/H] = +0.01 {+-} 0.08. The planetary companion has a mass of 4.063 {+-} 0.161 M{sub J} and a radius of 1.024 {+-} 0.092 R{sub J} yielding a mean density of 4.68{sup +1.59}{sub -0.99} g cm{sup -3}. HAT-P-21b is a borderline object between the pM and pL class planets, and the transits occur near apastron. HAT-P-22b orbits the bright V = 9.732 G5 dwarf star HD 233731 on a circular orbit, with a period P = 3.212220 {+-} 0.000009 days, transit epoch T{sub c} = 2454930.22001 {+-} 0.00025, and transit duration 0.1196 {+-} 0.0014 days. The host star has a mass of 0.92 {+-} 0.03 M{sub Sun }, radius of 1.04 {+-} 0.04 R{sub Sun }, effective temperature 5302 {+-} 80 K, and metallicity [Fe/H] = +0.24 {+-} 0.08. The planet has a mass of 2.147 {+-} 0.061 M{sub J} and a compact radius of 1.080 {+-} 0.058 R{sub J} yielding a mean density of 2.11{sup +0.40}{sub -0.29} g cm{sup -3}. The host star also

  2. Constraining the Kehagias-Sfetsos Solution of the Ho!ava-Lifshitz Modified Gravity with Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo; Ruggiero, Matteo Luca

    We consider the Kehagias-Sfetsos (KS) solution in the Ho!ava-Lifshitz gravity that is the analog of the general relativistic Schwarzschild black hole. In the weak-field and slow-motion approximation, we, first, work out the correction to the third Kepler law of a test particle induced by such a solution. Then, we compare it to the phenomenologically determined orbital period of the transiting extrasolar planet HD209458b "Osiris" to preliminarily obtain an order-ofmagnitude lower bound on the KS dimensionless parameter ω0 ≥2265; 1.4 " 10-18. As suggestions for further analyses, the entire data set of HD209458b should be re-processed by explicitly modeling KS gravity as well, and one or more dedicated solve-for parameter(s) should be estimated.

  3. Planet hunters. VII. Discovery of a new low-mass, low-density planet (PH3 C) orbiting Kepler-289 with mass measurements of two additional planets (PH3 B and D)

    SciTech Connect

    Schmitt, Joseph R.; Fischer, Debra A.; Wang, Ji; Margossian, Charles; Brewer, John M.; Giguere, Matthew J.; Agol, Eric; Deck, Katherine M.; Rogers, Leslie A.; Gazak, J. Zachary; Holman, Matthew J.; Jek, Kian J.; Omohundro, Mark R.; Winarski, Troy; Lintott, Chris; Simpson, Robert; Lynn, Stuart; Parrish, Michael; Schawinski, Kevin; Schwamb, Megan E.; and others

    2014-11-10

    We report the discovery of one newly confirmed planet (P = 66.06 days, R {sub P} = 2.68 ± 0.17 R {sub ⊕}) and mass determinations of two previously validated Kepler planets, Kepler-289 b (P = 34.55 days, R {sub P} = 2.15 ± 0.10 R {sub ⊕}) and Kepler-289-c (P = 125.85 days, R {sub P} = 11.59 ± 0.10 R {sub ⊕}), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a 1:2:4 Laplace resonance. The outer planet has very deep (∼1.3%), high signal-to-noise transits, which puts extremely tight constraints on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young (∼1 Gyr as determined by isochrones and gyrochronology), Sun-like star with M {sub *} = 1.08 ± 0.02 M {sub ☉}, R {sub *} = 1.00 ± 0.02 R {sub ☉}, and T {sub eff} = 5990 ± 38 K. The middle planet's large TTV amplitude (∼5 hr) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be M = 7.3 ± 6.8 M {sub ⊕}, 4.0 ± 0.9M {sub ⊕}, and M = 132 ± 17 M {sub ⊕}, which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, ρ = 1.2 ± 0.3 g cm{sup –3} for a planet of its mass, requiring a substantial H/He atmosphere of 2.1{sub −0.3}{sup +0.8}% by mass, and joins a growing population of low-mass, low-density planets.

  4. Light-curve analysis of KIC 12557548b: an extrasolar planet with a comet-like tail

    NASA Astrophysics Data System (ADS)

    Budaj, J.

    2013-09-01

    Context. An object with a very peculiar light curve was recently discovered using Kepler data. When this object was discovered, it was suggested that this object may be a transiting disintegrating extrasolar planet with a comet-like dusty tail. Aims: We aim to verify this model by modelling the light curve and put constraints on the geometry of the dust region and various dust properties. Methods: We modified the code SHELLSPEC, which is designed for modelling interacting binary stars to calculate the light curves of such planets. Mie absorption and scattering on spherical dust grains with realistic dust opacities, phase functions, and a finite radius of the source of the scattered light are taken into account Results: The light curve is reanalysed using long- and short-cadence Kepler observations from the first 14 quarters. The orbital period of the planet was improved. We prove that the peculiar light curve agrees with the idea of a planet with a comet-like tail. The light curve has a prominent pre-transit brightening and a less prominent post-transit brightening. Both are caused by the forward scattering and are a strong function of the particle size. This feature enabled us to estimate a typical particle size (radius) in the dust tail of about 0.1-1 micron. However, there is an indication that the particle size changes (decreases) along the tail. The dust density in the tail is a steep decreasing function of the distance from the planet, which indicates a significant tail destruction caused by the star-planet interaction. Several possible combinations of other dust properties are tabulated. We reveal interesting periodic long-term evolution of the tail on a time scale of about 1.3 years and also argue that the "planet" does not show a uniform behaviour, but may have at least two constituents. This exoplanet's tail evolution may find an analogy in the comet tail disconnection events caused by the magnetic/coronal activity of the Sun while the light curve with

  5. Planetary Formation: From the Earth and Moon to Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases-such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Specific issues to be discussed include: (1) how large a solid core is needed to initiate rapid accumulation of gas? (2) can giant planets form very close to stars? (3) could a giant impact leading to lunar formation have occurred approx. 100 million years after the condensation of the oldest meteorites?

  6. Design and Verification of External Occulters for Direct Imaging of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Cady, Eric

    2011-01-01

    An occulter is an optical element which is placed in front of the telescope to block most of the light from a star before it reaches the optics inside, without blocking the planet.In our case, we use two spacecraft ying in formation: First has its edge shaped to cancel the starlight Second is the telescope which images the star and planet

  7. Planetary Formation: From the Earth and Moon to Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Specific issues to be discussed include: (1) how large a solid core is needed to initiate rapid accumulation of gas? (2) can giant planets form very close to stars? (3) could a giant impact leading to lunar formation have occurred approximately 100 million years after the condensation of the oldest meteorites?

  8. Atmospheric circulation modeling of super Earths and terrestrial extrasolar planets using the SPARC/MITgcm

    NASA Astrophysics Data System (ADS)

    Kataria, T.; Showman, A. P.; Haberle, R. M.; Marley, M. S.; Fortney, J. J.; Freedman, R. S.

    2013-12-01

    The field of exoplanets continues to be a booming field of research in astronomy and planetary science, with numerous ground-based (e.g., SuperWASP, HARPS-N and S) and space-based surveys (e.g., Kepler) that detect and characterize planets ranging from hot Jupiters, Jovian-sized planets orbiting less than 0.1 AU from their star, to super Earths and terrestrial exoplanets, planets that have masses equal to or less than 10 times that of Earth with a range of orbital distances. Atmospheric circulation modeling plays an important role in the characterization of these planets, helping to constrain observations that probe their atmospheres. These models have proven successful in understanding observations of transiting exoplanets (when the planet passes in front of the star along our line of sight) particularly when the planet is passing through secondary eclipse (when the planet's dayside is visible). In modeling super Earths and terrestrial exoplanets, we must consider not only planets with thick fluid envelopes, but also traditional terrestrial planets with solid surfaces and thinner atmospheres. To that end, we present results from studies investigating the atmospheric circulation of these classes of planets using the SPARC/MITgcm, a state-of-the-art model which couples the MIT General Circulation Model with a plane-parallel, two-stream, non-gray radiative transfer model. We will present results from two studies, the first focusing on the circulation of GJ 1214b, a super-Earth detected by the MEarth ground-based survey, and a second study which explores the circulation of terrestrial exoplanets orbiting M-dwarfs.

  9. Low-mass protoplanetary disk of the herbig Ae star DDser: Thermal radiation of dust and possible presence of massive planets

    NASA Astrophysics Data System (ADS)

    Antonyuk, K. A.; Shakhovskoy, D. N.; Belan, S. P.; Rostopchina, A. N.

    2015-07-01

    We detected thermal IR radiation from DDSer, a low-activity UXOri-type star, the source of which is a disk with a complex structure (an inner ring with the dust temperature of about 900 K and an outer disk with the temperature below 300 K). The 15.1-year period, which we estimated from our longterm photometric observations, indicates the perturbation of this ring by a low-mass companion (a planet perhaps) with an orbital radius of 8 a.u. In general, the detected characteristics of the DDSer disk (a dust ring with the densitymodulated with a 10-year scale period, the presence of compact dust clumps inside the ring's inner lobe) are almost identical to the characteristics of the RZ Psc disk, where an active asteroid belt inside the orbit of a planet or a similar low-mass companion is assumed. Although the suggestion about a collisional source of the dust in these systems is disputable, the complex structure of their disks,manifested in the IR spectrum shape and photometric variability, especially the long-period variability, gives evidence for massive planets already formed in these systems.

  10. The Effect of Host Star Spectral Energy Distribution and Ice-Albedo Feedback on the Climate of Extrasolar Planets

    PubMed Central

    Meadows, Victoria S.; Bitz, Cecilia M.; Pierrehumbert, Raymond T.; Joshi, Manoj M.; Robinson, Tyler D.

    2013-01-01

    ice coverage. The surface ice-albedo feedback effect becomes less important at the outer edge of the habitable zone, where atmospheric CO2 could be expected to be high such that it maintains clement conditions for surface liquid water. We showed that ∼3–10 bar of CO2 will entirely mask the climatic effect of ice and snow, leaving the outer limits of the habitable zone unaffected by the spectral dependence of water ice and snow albedo. However, less CO2 is needed to maintain open water for a planet orbiting an M-dwarf star than would be the case for hotter main-sequence stars. Key Words: Extrasolar planets—M stars—Habitable zone—Snowball Earth. Astrobiology 13, 715–739. PMID:23855332

  11. A matched filter method for ground-based sub-noise detection of terrestrial extrasolar planets in eclipsing binaries: application to CM Draconis

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.; Doyle, L. R.; Cullers, D. K.

    1996-01-01

    The photometric detection of extrasolar planets by transits in eclipsing binary systems can be significantly improved by cross-correlating the observational light curves with synthetic models of possible planetary transit features, essentially a matched filter approach. We demonstrate the utility and application of this transit detection algorithm for ground-based detections of terrestrial-sized (Earth-to-Neptune radii) extrasolar planets in the dwarf M-star eclipsing binary system CM Draconis. Preliminary photometric observational data of this system demonstrate that the observational noise is well characterized as white and Gaussian at the observational time steps required for precision photometric measurements. Depending on planet formation scenarios, terrestrial-sized planets may form quite close to this low-luminosity system. We demonstrate, for example, that planets as small as 1.4 Earth radii with periods on the order of a few months in the CM Draconis system could be detected at the 99.9% confidence level in less than a year using 1-m class telescopes from the ground. This result contradicts commonly held assumptions limiting present ground-based efforts to, at best, detections of gas giant planets after several years of observation. This method can be readily extended to a number of other larger star systems with the utilization of larger telescopes and longer observing times. Its extension to spacecraft observations should also allow the determination of the presence of terrestrial-sized planets in nearly 100 other known eclipsing binary systems.

  12. The Search for Extrasolar Planets by Means of the Radial-Velocity Spectral Method and Astrometry

    NASA Astrophysics Data System (ADS)

    Ksanfomaliti, L. V.

    The discovery of companion planets of alien stars (exoplanets) commands the interest of the scientific community all over the world. The factual data in the paper appearing below should help to draw the attention of Russian specialists to this fascinating problem. The data make it possible to assess the feasibility of identifying exoplanets, using available instruments, by detecting indications of Keplerian Doppler shifts in stellar motion. Consideration is given to the effects produced by the gravitational pull exerted on a star by companion planets similar to the main planets of the Solar System. The signatures of companion planets observed from a distance of 10 pc are evaluated. Some specific experimental results, together with the corresponding radial velocities and angular wobbles of the star, are given. Information about achieved thresholds and the techniques by which they were reached is summarized.

  13. A TWO-DIMENSIONAL INFRARED MAP OF THE EXTRASOLAR PLANET HD 189733b

    SciTech Connect

    Majeau, Carl; Agol, Eric; Cowan, Nicolas B.

    2012-03-10

    We derive the first secondary eclipse map of an exoplanet, HD 189733b, based on Spitzer IRAC 8 {mu}m data. We develop two complementary techniques for deriving the two-dimensional planet intensity: regularized slice mapping and spherical harmonic mapping. Both techniques give similar derived intensity maps for the infrared dayside flux of the planet, while the spherical harmonic method can be extended to include phase variation data which better constrain the map. The longitudinal offset of the dayside hot spot is consistent with that found in prior studies, strengthening the claim of super-rotating winds, and eliminating the possibility of phase variations being caused by stellar variability. The latitude of the hot spot is within 12.{sup 0}5 (68% confidence) of the planet's equator, confirming the predictions of general circulation models for hot Jupiters and indicative of a small planet obliquity.

  14. The Inner Edge of the Habitable Zone for Synchronously Rotating Planets around Low-mass Stars Using General Circulation Models

    NASA Astrophysics Data System (ADS)

    Kopparapu, Ravi kumar; Wolf, Eric T.; Haqq-Misra, Jacob; Yang, Jun; Kasting, James F.; Meadows, Victoria; Terrien, Ryan; Mahadevan, Suvrath

    2016-03-01

    Terrestrial planets at the inner edge of the habitable zone (HZ) of late-K and M-dwarf stars are expected to be in synchronous rotation, as a consequence of strong tidal interactions with their host stars. Previous global climate model (GCM) studies have shown that, for slowly rotating planets, strong convection at the substellar point can create optically thick water clouds, increasing the planetary albedo, and thus stabilizing the climate against a thermal runaway. However these studies did not use self-consistent orbital/rotational periods for synchronously rotating planets placed at different distances from the host star. Here we provide new estimates of the inner edge of the HZ for synchronously rotating terrestrial planets around late-K and M-dwarf stars using a 3D Earth-analog GCM with self-consistent relationships between stellar metallicity, stellar effective temperature, and the planetary orbital/rotational period. We find that both atmospheric dynamics and the efficacy of the substellar cloud deck are sensitive to the precise rotation rate of the planet. Around mid-to-late M-dwarf stars with low metallicity, planetary rotation rates at the inner edge of the HZ become faster, and the inner edge of the HZ is farther away from the host stars than in previous GCM studies. For an Earth-sized planet, the dynamical regime of the substellar clouds begins to transition as the rotation rate approaches ∼10 days. These faster rotation rates produce stronger zonal winds that encircle the planet and smear the substellar clouds around it, lowering the planetary albedo, and causing the onset of the water-vapor greenhouse climatic instability to occur at up to ∼25% lower incident stellar fluxes than found in previous GCM studies. For mid-to-late M-dwarf stars with high metallicity and for mid-K to early-M stars, we agree with previous studies.

  15. An Ancient Extrasolar System with Five Sub-Earth-size Planets

    NASA Astrophysics Data System (ADS)

    Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; Cochran, W.; Burke, C. J.; Isaacson, H.; Quintana, E. V.; Davies, G. R.; Silva Aguirre, V.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, J. F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, D. A.; Kawaler, S. D.; Kjeldsen, H.; Lund, M. N.; Marcy, G. W.; Sousa, S. G.; Sozzetti, A.; White, T. R.

    2015-02-01

    The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation.

  16. Types of Information Expected from a Photometric Search for Extra-Solar Planets

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Bell, James, III; Cuzzi, Jeffrey N. (Technical Monitor)

    1994-01-01

    The current theory postulates that planets are a consequence of the formation of stars from viscous accretion disks. Condensation from the hotter, inner portion of the accretion disk favors the formation of small rocky planets in the inner portion and the formation of gas giants in the cuter, cooler part. Consequently, terrestrial-type planets in inner orbits must be commonplace (Wetheril 1991). From the geometry of the situation (Borucki and Summers 1984), it can be shown that 1% of those planetary systems that resemble our solar system should show transits for Earth-sized (or larger) planets. Thus a photometric satellite that uses a wide field of view telescope and a large CCD array to simultaneously monitor 5000 target stars should detect 50 planetary systems. To verify that regularly recurring transits are occurring rather than statistical fluctuations of the stellar flux, demands observations that extend over several orbital periods so that the constancy of the orbital period, signal amplitude, and duration can be measured. Therefore, to examine the region from Mercury's orbit to that of the Earth requires a duration of three years whereas a search out to the orbit of mars requires about six years. The results of the observations should provide estimates of the distributions of planetary size and orbital radius, and the frequency of planetary systems that have Earth-sized planets in inner orbits. Because approximately one half of the star systems observed will be binary systems, the frequency of planetary systems orbit ' ing either one or both of the stars can also be determined. Furthermore, the complexity of the photometric signature of a planet transiting a pair of stars provides enough information to estimate the eccentricities of the planetary orbits. In summary, the statistical evidence from a photometric search of solar-like stars should be able to either confirm or deny the applicability of the current theory of planet formation and provide new

  17. AN ANCIENT EXTRASOLAR SYSTEM WITH FIVE SUB-EARTH-SIZE PLANETS

    SciTech Connect

    Campante, T. L.; Davies, G. R.; Chaplin, W. J.; Handberg, R.; Barclay, T.; Huber, D.; Burke, C. J.; Quintana, E. V.; Swift, J. J.; Adibekyan, V. Zh.; Cochran, W.; Isaacson, H.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; and others

    2015-02-01

    The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation.

  18. Structure of the Edgeworth-Kuiper Belt (EKB) Dust Disk and Implications for Extrasolar Planet(s) epsilon Eridani

    NASA Technical Reports Server (NTRS)

    Liou, J. -C.; Zook, H. A.; Greaves, J. S.; Holland, W. S.; Boehnhardt, H.; Hahn, J. M.

    2000-01-01

    Numerical simulations of the orbital evolution of dust particles from Edgeworth-Kuiper Belt (EKB) objects show that the three giant planets, Neptune, Jupiter, and Saturn impose distinct and dramatic signatures on the overall distribution of EKB dust particles. The features are very similar to those observed in the dust disk around the nearby star Eridani. Numerical simulations of dust particles in the epsilon Eridani system show that planetary perturbations may be responsible for the observed features

  19. PASTIS: Bayesian extrasolar planet validation - I. General framework, models, and performance

    NASA Astrophysics Data System (ADS)

    Díaz, R. F.; Almenara, J. M.; Santerne, A.; Moutou, C.; Lethuillier, A.; Deleuil, M.

    2014-06-01

    A large fraction of the smallest transiting planet candidates discovered by the Kepler and CoRoT space missions cannot be confirmed by a dynamical measurement of the mass using currently available observing facilities. To establish their planetary nature, the concept of planet validation has been advanced. This technique compares the probability of the planetary hypothesis against that of all reasonably conceivable alternative false positive (FP) hypotheses. The candidate is considered as validated if the posterior probability of the planetary hypothesis is sufficiently larger than the sum of the probabilities of all FP scenarios. In this paper, we present PASTIS, the Planet Analysis and Small Transit Investigation Software, a tool designed to perform a rigorous model comparison of the hypotheses involved in the problem of planet validation, and to fully exploit the information available in the candidate light curves. PASTIS self-consistently models the transit light curves and follow-up observations. Its object-oriented structure offers a large flexibility for defining the scenarios to be compared. The performance is explored using artificial transit light curves of planets and FPs with a realistic error distribution obtained from a Kepler light curve. We find that data support the correct hypothesis strongly only when the signal is high enough (transit signal-to-noise ratio above 50 for the planet case) and remain inconclusive otherwise. PLAnetary Transits and Oscillations of stars (PLATO) shall provide transits with high enough signal-to-noise ratio, but to establish the true nature of the vast majority of Kepler and CoRoT transit candidates additional data or strong reliance on hypotheses priors is needed.

  20. Simulations of Detectability of Extrasolar Planets by a Joint Doppler and WFIRST-AFTA Coronagraph Survey

    NASA Astrophysics Data System (ADS)

    Chontos, Ashley; Macintosh, Bruce; Nielsen, Eric L.

    2016-01-01

    A long-term goal for the astronomical community is to image and characterize an Earth-like planet. The WFIRST-AFTA space mission will make advancements towards this goal. WFIRST will include a coronagraphic instrument to discover and characterize new exoplanets and to better characterize already known exoplanets. We present results of simulations using a Doppler survey to find lower mass planets as possible targets for WFIRST. For simulations, simplified completeness estimates (Howard & Fulton 2014) are used to test the sensitivity of a prospective Doppler campaign. We use data from the HARPS spectrograph to determine exposure times needed to achieve 1 m/s uncertainty. Stellar jitter was randomly sampled from a uniform distribution based on spectral type, treating OBA-type, FGK-type, and M-type stars separately. For survey parameters, we use campaign parameters from the WIYN telescope, assuming 10 hours per night at 100 nights per year over 6 years. In any one simulation, we find roughly 45-50 new planets that are potentially observable by WFIRST. By limiting our targets to FGKM type stars within 10 parsecs, we expect one of those planets to be less than 10 ME.

  1. 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.

  2. Simulations of Detectability of Extrasolar Planets by a Joint Doppler and WFIRST-AFTA Coronagraph Survey

    NASA Astrophysics Data System (ADS)

    Chontos, Ashley; Macintosh, Bruce; Nielsen, Eric

    2016-03-01

    A long-term goal for the astronomical community is to image and characterize an Earth-like planet. The WFIRST-AFTA space mission will make advancements towards this goal. WFIRST will include a coronagraphic instrument to discover and characterize new exoplanets and to better characterize already known exoplanets. Although the WFIRST coronagraph will be very powerful, mission time to discover new planetary systems is limited. Identifying promising targets in advance could significantly enhance the scientific yield. We present results of simulations using a Doppler survey to find lower mass planets as possible targets for WFIRST. For simulations, simplified completeness estimates (Howard & Fulton 2014) are used to test the sensitivity of a prospective Doppler campaign. We use data from the HARPS spectrograph to determine exposure times needed to achieve 1 m/s uncertainty. Stellar jitter was randomly sampled from a uniform distribution based on spectral type, treating OBA-type, FGK-type, and M-type stars separately. For survey parameters, we use campaign parameters from the WIYN telescope, assuming 10 hours per night at 100 nights per year over 6 years. In any one simulation, we find roughly 45-50 new planets that are potentially observable by WFIRST. By limiting our targets to FGKM type stars within 10 parsecs, we expect one of those planets to be less than 10 Earth masses.

  3. Models of very-low-mass stars, brown dwarfs and exoplanets.

    PubMed

    Allard, F; Homeier, D; Freytag, B

    2012-06-13

    Within the next few years, GAIA and several instruments aiming to image extrasolar planets will be ready. In parallel, low-mass planets are being sought around red dwarfs, which offer more favourable conditions, for both radial velocity detection and transit studies, than solar-type stars. In this paper, the authors of a model atmosphere code that has allowed the detection of water vapour in the atmosphere of hot Jupiters review recent advances in modelling the stellar to substellar transition. The revised solar oxygen abundances and cloud model allow the photometric and spectroscopic properties of this transition to be reproduced for the first time. Also presented are highlight results of a model atmosphere grid for stars, brown dwarfs and extrasolar planets. PMID:22547243

  4. Models of very-low-mass stars, brown dwarfs and exoplanets

    PubMed Central

    Allard, F.; Homeier, D.; Freytag, B.

    2012-01-01

    Within the next few years, GAIA and several instruments aiming to image extrasolar planets will be ready. In parallel, low-mass planets are being sought around red dwarfs, which offer more favourable conditions, for both radial velocity detection and transit studies, than solar-type stars. In this paper, the authors of a model atmosphere code that has allowed the detection of water vapour in the atmosphere of hot Jupiters review recent advances in modelling the stellar to substellar transition. The revised solar oxygen abundances and cloud model allow the photometric and spectroscopic properties of this transition to be reproduced for the first time. Also presented are highlight results of a model atmosphere grid for stars, brown dwarfs and extrasolar planets. PMID:22547243

  5. Implications of (Less) Accurate Mass-Radius-Measurements for the Habitability of Extrasolar Terrestrial Planets: Why Do We Need PLATO?

    NASA Astrophysics Data System (ADS)

    Noack, L.; Wagner, F. W.; Plesa, A.-C.; Höning, D.; Sohl, F.; Breuer, D.; Rauer, H.

    2012-04-01

    Several space missions (CoRoT, Kepler and others) already provided promising candidates for terrestrial exoplanets (i.e. with masses less than about 10 Earth masses) and thereby triggered an exciting new research branch of planetary modelling to investigate the possible habitability of such planets. Earth analogues (low-mass planets with an Earth-like structure and composition) are likely to be found in the near future with new missions such as the proposed M3 mission PLATO. Planets may be more diverse in the universe than they are in the solar system. Our neighbouring planets in the habitable zone are all terrestrial by the means of being differentiated into an iron core, a silicate mantle and a crust. To reliably determine the interior structure of an exoplanet, measurements of mass and radius have to be sufficiently accurate (around +/-2% error allowed for the radius and +/-5% for the mass). An Earth-size planet with an Earth-like mass but an expected error of ~15% in mass for example may have either a Mercury-like, an Earth-like or a Moon-like (i.e. small iron core) structure [1,2]. Even though the atmospheric escape is not strongly influenced by the interior structure, the outgassing of volatiles and the likeliness of plate tectonics and an ongoing carbon-cycle may be very different. Our investigations show, that a planet with a small silicate mantle is less likely to shift into the plate-tectonics regime, cools faster (which may lead to the loss of a magnetic field after a short time) and outgasses less volatiles than a planet with the same mass but a large silicate mantle and small iron core. To be able to address the habitability of exoplanets, space missions such as PLATO, which can lead up to 2% accuracy in radius [3], are extremely important. Moreover, information about the occurrence of different planetary types helps us to better understand the formation of planetary systems and to further constrain the Drake's equation, which gives an estimate of the

  6. ADAPTIVE ANNEALED IMPORTANCE SAMPLING FOR MULTIMODAL POSTERIOR EXPLORATION AND MODEL SELECTION WITH APPLICATION TO EXTRASOLAR PLANET DETECTION

    SciTech Connect

    Liu, Bin

    2014-07-01

    We describe an algorithm that can adaptively provide mixture summaries of multimodal posterior distributions. The parameter space of the involved posteriors ranges in size from a few dimensions to dozens of dimensions. This work was motivated by an astrophysical problem called extrasolar planet (exoplanet) detection, wherein the computation of stochastic integrals that are required for Bayesian model comparison is challenging. The difficulty comes from the highly nonlinear models that lead to multimodal posterior distributions. We resort to importance sampling (IS) to estimate the integrals, and thus translate the problem to be how to find a parametric approximation of the posterior. To capture the multimodal structure in the posterior, we initialize a mixture proposal distribution and then tailor its parameters elaborately to make it resemble the posterior to the greatest extent possible. We use the effective sample size (ESS) calculated based on the IS draws to measure the degree of approximation. The bigger the ESS is, the better the proposal resembles the posterior. A difficulty within this tailoring operation lies in the adjustment of the number of mixing components in the mixture proposal. Brute force methods just preset it as a large constant, which leads to an increase in the required computational resources. We provide an iterative delete/merge/add process, which works in tandem with an expectation-maximization step to tailor such a number online. The efficiency of our proposed method is tested via both simulation studies and real exoplanet data analysis.

  7. THERMOCHEMICAL AND PHOTOCHEMICAL KINETICS IN COOLER HYDROGEN-DOMINATED EXTRASOLAR PLANETS: A METHANE-POOR GJ436b?

    SciTech Connect

    Line, Michael R.; Yung, Yuk L.; Vasisht, Gautam; Chen, Pin; Angerhausen, D. E-mail: gv@s383.jpl.nasa.gov

    2011-09-01

    We introduce a thermochemical kinetics and photochemical model. We use high-temperature bidirectional reaction rates for important H, C, O, and N reactions (most importantly for CH{sub 4} to CO interconversion), allowing us to attain thermochemical equilibrium, deep in an atmosphere, purely kinetically. This allows the chemical modeling of an entire atmosphere, from deep-atmosphere thermochemical equilibrium to the photochemically dominated regime. We use our model to explore the atmospheric chemistry of cooler (T{sub eff} < 10{sup 3} K) extrasolar giant planets. In particular, we choose to model the nearby hot-Neptune GJ436b, the only planet in this temperature regime for which spectroscopic measurements and estimates of chemical abundances now exist. Recent Spitzer measurements with retrieval have shown that methane is driven strongly out of equilibrium and is deeply depleted on the day side of GJ436b, whereas quenched carbon monoxide is abundant. This is surprising because GJ436b is cooler than many of the heavily irradiated hot Jovians and thermally favorable for CH{sub 4}, and thus requires an efficient mechanism for destroying it. We include realistic estimates of ultraviolet flux from the parent dM star GJ436, to bound the direct photolysis and photosensitized depletion of CH{sub 4}. While our models indicate fairly rich disequilibrium conditions are likely in cooler exoplanets over a range of planetary metallicities, we are unable to generate the conditions for substantial CH{sub 4} destruction. One possibility is an anomalous source of abundant H atoms between 0.01 and 1 bars (which attack CH{sub 4}), but we cannot as yet identify an efficient means to produce these hot atoms.

  8. Optimal planning of radial velocity observations for multi-planet extrasolar systems

    NASA Astrophysics Data System (ADS)

    Baluev, R. V.

    2010-04-01

    Applications of the theory of the optimal design of radial-velocity planet-search surveys are discussed. Two important practical problems are considered. The first problem is finding the time for future observations to yield the maximum improvement of the accuracy of exoplanetary orbital parameters and masses. In this case, the optimal scheduling rules are designed to maximize the determinant of the Fisher information matrix (the so-called D-optimality criterion). This method is asymptotically equivalent to the maximization of the expected gain of the Shannon information provided by making extra observations. The second problem is finding the most favourable observing time for distinguishing alternative orbital fits (the design of discriminating experiments). In this case, the optimal scheduling rules are designed to maximize the Kullback-Leibler divergence information. We also consider the potential efficiency of these methods of optimal planning of radial velocity observations for multi-planet systems.

  9. Photon-Weighted Midpoint Exposure Meter for Keck/HIRES Extrasolar Planet Research

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA Grant was received for research involving the construction of a photon-weighting midpoint exposure meter for the Keck HIRES spectrometer, and for support of our NASA/Keck-based planet research with this instrumentation. The research funds were also to be used to make our iodine cell calibration system and exposure meter available to the NASA Keck observing community. Progress this past year, the second of the 3-year granting period, involved work in 4 areas: 1) Further construction of the midpoint exposure meter. 2) Assisting observers with use of the Iodine system. 3) Acquisition of precision radial velocity data on our program star sample with continued monitoring to proceed in subsequent years as available telescope time permits. 4) Reduction and analysis of incoming precision radial velocity data to reject problematic and uninteresting program stars, and to identify promising planet candidates.

  10. An extended upper atmosphere around the extrasolar planet HD209458b.

    PubMed

    Vidal-Madjar, A; Des Etangs, A Lecavelier; Désert, J-M; Ballester, G E; Ferlet, R; Hébrard, G; Mayor, M

    2003-03-13

    The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed. Together with radial velocity measurements, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature, only the dense lower atmosphere of HD209458b has been observed, through the detection of neutral sodium absorption. Here we report the detection of atomic hydrogen absorption in the stellar Lyman alpha line during three transits of HD209458b. An absorption of 15 +/- 4% (1sigma) is observed. Comparison with models shows that this absorption should take place beyond the Roche limit and therefore can be understood in terms of escaping hydrogen atoms. PMID:12634780

  11. Insights into Planet Formation from Debris Disks - II. Giant Impacts in Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Wyatt, Mark C.; Jackson, Alan P.

    2016-03-01

    Giant impacts refer to collisions between two objects each of which is massive enough to be considered at least a planetary embryo. The putative collision suffered by the proto-Earth that created the Moon is a prime example, though most Solar System bodies bear signatures of such collisions. Current planet formation models predict that an epoch of giant impacts may be inevitable, and observations of debris around other stars are providing mounting evidence that giant impacts feature in the evolution of many planetary systems. This chapter reviews giant impacts, focussing on what we can learn about planet formation by studying debris around other stars. Giant impact debris evolves through mutual collisions and dynamical interactions with planets. General aspects of this evolution are outlined, noting the importance of the collision-point geometry. The detectability of the debris is discussed using the example of the Moon-forming impact. Such debris could be detectable around another star up to 10 Myr post-impact, but model uncertainties could reduce detectability to a few 100 yr window. Nevertheless the 3 % of young stars with debris at levels expected during terrestrial planet formation provide valuable constraints on formation models; implications for super-Earth formation are also discussed. Variability recently observed in some bright disks promises to illuminate the evolution during the earliest phases when vapour condensates may be optically thick and acutely affected by the collision-point geometry. The outer reaches of planetary systems may also exhibit signatures of giant impacts, such as the clumpy debris structures seen around some stars.

  12. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. III. BREAKDOWN CONDITIONS FOR MINERAL CLOUDS

    SciTech Connect

    Helling, Ch.; Jardine, M.; Stark, C.; Diver, D.

    2013-04-20

    Electric discharges were detected directly in the cloudy atmospheres of Earth, Jupiter, and Saturn, are debatable for Venus, and indirectly inferred for Neptune and Uranus in our solar system. Sprites (and other types of transient luminous events) have been detected only on Earth, and are theoretically predicted for Jupiter, Saturn, and Venus. Cloud formation is a common phenomenon in ultra-cool atmospheres such as in brown dwarf and extrasolar planetary atmospheres. Cloud particles can be expected to carry considerable charges which may trigger discharge events via small-scale processes between individual cloud particles (intra-cloud discharges) or large-scale processes between clouds (inter-cloud discharges). We investigate electrostatic breakdown characteristics, like critical field strengths and critical charge densities per surface, to demonstrate under which conditions mineral clouds undergo electric discharge events which may trigger or be responsible for sporadic X-ray emission. We apply results from our kinetic dust cloud formation model that is part of the DRIFT-PHOENIX model atmosphere simulations. We present a first investigation of the dependence of the breakdown conditions in brown dwarf and giant gas exoplanets on the local gas-phase chemistry, the effective temperature, and primordial gas-phase metallicity. Our results suggest that different intra-cloud discharge processes dominate at different heights inside mineral clouds: local coronal (point discharges) and small-scale sparks at the bottom region of the cloud where the gas density is high, and flow discharges and large-scale sparks near, and maybe above, the cloud top. The comparison of the thermal degree of ionization and the number density of cloud particles allows us to suggest the efficiency with which discharges will occur in planetary atmospheres.

  13. A Comparison of Observationally Determined Radii with Theoretical Radius Predictions for Short-Period Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Laughlin, Gregory; Wolf, Aaron; Vanmunster, Tonny; Bodenheimer, Peter; Fischer, Debra; Marcy, Geoff; Butler, Paul; Vogt, Steve

    2005-03-01

    Two extrasolar planets, HD 209458b and TrES-1, are currently known to transit bright parent stars for which physical properties can be accurately determined. The two transiting planets have very similar masses and periods and hence invite detailed comparisons between their observed and theoretically predicted properties. In this paper, we carry out these comparisons. We first report photometric and spectroscopic follow-up observations of TrES-1, and we use these observations to obtain improved estimates for the planetary radius, Rpl=(1.08+/-0.05)RJ, and the planetary mass, Mpl=(0.729+/-0.036)MJ. We also confirm that the inclination estimate of the planetary orbit as i=88.2d. These values agree with those obtained by Alonso et al. in their discovery paper, but the uncertainty in the planet radius has been improved as a result of both high-cadence photometry of two full transits and from independent radius determinations for the V=11.8 K0 V parent star. We derive estimates for the TrES-1 stellar parameters of R*/Rsolar=0.83+/-0.03 (by combining independent estimates from stellar models, high-resolution spectra, and transit light curve fitting) M*/Msolar=0.87+/-0.05 (via fitting to evolutionary tracks), Teff=5214+/-23K, [Me/H]=0.001+/-0.04, rotational velocity Vsin(i)=1.08+/-0.3kms-1, logg=4.52+/-0.05dex, logL*/Lsolar=-0.32, d=157+/-6pc, and an age of τ=4+/-2Gyr. These estimates of the physical properties of the system allow us to compute evolutionary models for the planet that result in a predicted radius of Rpl=1.05RJ for a model that contains an incompressible 20 M⊕ core and a radius Rpl=1.09RJ for a model without a core. We use our grids of planetary evolution models to show that, with standard assumptions, our code also obtains good agreement with the observed radii of the other recently discovered transiting planets, including OGLE-TR-56b, OGLE-TR-111b, OGLE-TR-113b, and OGLE-TR-132b. We report an updated radius for HD 209458b of Rpl=(1.32+/-0.05)RJ, based on

  14. Galactic cosmic rays on extrasolar Earth-like planets. II. Atmospheric implications

    NASA Astrophysics Data System (ADS)

    Grießmeier, J.-M.; Tabataba-Vakili, F.; Stadelmann, A.; Grenfell, J. L.; Atri, D.

    2016-03-01

    Context. Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields. As described in the companion article (Paper I), a weak magnetic field results in a high flux of galactic cosmic rays to the top of the planetary atmosphere. Aims: We investigate effects that may result from a high flux of galactic cosmic rays both throughout the atmosphere and at the planetary surface. Methods: Using an air shower approach, we calculate how the atmospheric chemistry and temperature change under the influence of galactic cosmic rays for Earth-like (N2-O2 dominated) atmospheres. We evaluate the production and destruction rate of atmospheric biosignature molecules. We derive planetary emission and transmission spectra to study the influence of galactic cosmic rays on biosignature detectability. We then calculate the resulting surface UV flux, the surface particle flux, and the associated equivalent biological dose rates. Results: We find that up to 20% of stratospheric ozone is destroyed by cosmic-ray protons. The effect on the planetary spectra, however, is negligible. The reduction of the planetary ozone layer leads to an increase in the weighted surface UV flux by two orders of magnitude under stellar UV flare conditions. The resulting biological effective dose rate is, however, too low to strongly affect surface life. We also examine the surface particle flux: For a planet with a terrestrial atmosphere (with a surface pressure of 1033 hPa), a reduction of the magnetic shielding efficiency can increase the biological radiation dose rate by a factor of two, which is non-critical for biological systems. For a planet with a weaker atmosphere (with a surface pressure of 97.8 hPa), the planetary magnetic field has a much stronger influence on the biological radiation dose, changing it by up to two orders of magnitude. Conclusions: For a planet with an Earth-like atmospheric pressure, weak or absent magnetospheric shielding against galactic cosmic

  15. The NASA-UC-UH Eta-Earth program. IV. A low-mass planet orbiting an M dwarf 3.6 PC from Earth

    SciTech Connect

    Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Fischer, Debra A.; Boyajian, Tabetha S.; Muirhead, Philip S.; Becker, Juliette C.; Henry, Gregory W.; Von Braun, Kaspar; Wright, Jason T.; Johnson, John Asher

    2014-10-10

    We report the discovery of a low-mass planet orbiting Gl 15 A based on radial velocities from the Eta-Earth Survey using HIRES at Keck Observatory. Gl 15 Ab is a planet with minimum mass Msin i = 5.35 ± 0.75 M {sub ⊕}, orbital period P = 11.4433 ± 0.0016 days, and an orbit that is consistent with circular. We characterize the host star using a variety of techniques. Photometric observations at Fairborn Observatory show no evidence for rotational modulation of spots at the orbital period to a limit of ∼0.1 mmag, thus supporting the existence of the planet. We detect a second RV signal with a period of 44 days that we attribute to rotational modulation of stellar surface features, as confirmed by optical photometry and the Ca II H and K activity indicator. Using infrared spectroscopy from Palomar-TripleSpec, we measure an M2 V spectral type and a sub-solar metallicity ([M/H] = –0.22, [Fe/H] = –0.32). We measure a stellar radius of 0.3863 ± 0.0021 R {sub ☉} based on interferometry from CHARA.

  16. SPITZER IRAC SECONDARY ECLIPSE PHOTOMETRY OF THE TRANSITING EXTRASOLAR PLANET HAT-P-1b

    SciTech Connect

    Todorov, Kamen; Deming, Drake; Harrington, Jospeph; Stevenson, Kevin B.; Bowman, William C.; Nymeyer, Sarah; Fortney, Jonathan J.; Bakos, Gaspar A.

    2010-01-01

    We report Spitzer/IRAC photometry of the transiting giant exoplanet HAT-P-1b during its secondary eclipse. This planet lies near the postulated boundary between the pM and pL-class of hot Jupiters, and is important as a test of models for temperature inversions in hot Jupiter atmospheres. We derive eclipse depths for HAT-P-1b, in units of the stellar flux, that are: 0.080% +- 0.008% [3.6 mum], 0.135% +- 0.022% [4.5 mum], 0.203% +- 0.031% [5.8 mum], and 0.238% +- 0.040% [8.0 mum]. These values are best fit using an atmosphere with a modest temperature inversion, intermediate between the archetype inverted atmosphere (HD 209458b) and a model without an inversion. The observations also suggest that this planet is radiating a large fraction of the available stellar irradiance on its dayside, with little available for redistribution by circulation. This planet has sometimes been speculated to be inflated by tidal dissipation, based on its large radius in discovery observations, and on a non-zero orbital eccentricity allowed by the radial velocity data. The timing of the secondary eclipse is very sensitive to orbital eccentricity, and we find that the central phase of the eclipse is 0.4999 +- 0.0005. The difference between the expected and observed phase indicates that the orbit is close to circular, with a 3sigma limit of |e cos omega| < 0.002.

  17. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. IV. THE EFFECT OF COSMIC RAYS

    SciTech Connect

    Rimmer, P. B.; Helling, Ch.

    2013-09-10

    Cosmic rays provide an important source for free electrons in Earth's atmosphere and also in dense interstellar regions where they produce a prevailing background ionization. We utilize a Monte Carlo cosmic ray transport model for particle energies of 10{sup 6} eV planets (T{sub eff} = 1000 K, 1500 K). For the model brown dwarf atmosphere, the electron fraction is enhanced significantly by cosmic rays when the pressure p{sub gas} < 10{sup -2} bar. Our example giant gas planet atmosphere suggests that the cosmic ray enhancement extends to 10{sup -4}-10{sup -2} bar, depending on the effective temperature. For the model atmosphere of the example giant gas planet considered here (T{sub eff} = 1000 K), cosmic rays bring the degree of ionization to f{sub e} {approx}> 10{sup -8} when p{sub gas} < 10{sup -8} bar, suggesting that this part of the atmosphere may behave as a weakly ionized plasma. Although cosmic rays enhance the degree of ionization by over three orders of magnitude in the upper atmosphere, the effect is not likely to be significant enough for sustained coupling of the magnetic field to the gas.

  18. PASTIS: Bayesian extrasolar planet validation - II. Constraining exoplanet blend scenarios using spectroscopic diagnoses

    NASA Astrophysics Data System (ADS)

    Santerne, A.; Díaz, R. F.; Almenara, J.-M.; Bouchy, F.; Deleuil, M.; Figueira, P.; Hébrard, G.; Moutou, C.; Rodionov, S.; Santos, N. C.

    2015-08-01

    The statistical validation of transiting exoplanets proved to be an efficient technique to secure the nature of small exoplanet signals which cannot be established by purely spectroscopic means. However, the spectroscopic diagnoses are providing us with useful constraints on the presence of blended stellar contaminants. In this paper, we present how a contaminating star affects the measurements of the various spectroscopic diagnoses as a function of the parameters of the target and contaminating stars using the model implemented into the PASTIS planet-validation software. We find particular cases for which a blend might produce a large radial velocity signal but no bisector variation. It might also produce a bisector variation anticorrelated with the radial velocity one, as in the case of stellar spots. In those cases, the full width at half-maximum variation provides complementary constraints. These results can be used to constrain blend scenarios for transiting planet candidates or radial velocity planets. We review all the spectroscopic diagnoses reported in the literature so far, especially the ones to monitor the line asymmetry. We estimate their uncertainty and compare their sensitivity to blends. Based on that, we recommend the use of BiGauss which is the most sensitive diagnosis to monitor line-profile asymmetry. In this paper, we also investigate the sensitivity of the radial velocities to constrain blend scenarios and develop a formalism to estimate the level of dilution of a blended signal. Finally, we apply our blend model to re-analyse the spectroscopic diagnoses of HD 16702, an unresolved face-on binary which exhibits bisector variations.

  19. Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

    SciTech Connect

    Barman, T S; Macintosh, B A; Konopacky, Q M; Marois, C

    2011-03-21

    Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a Hydrogen-rich atmosphere. Only weak CH{sub 4} absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH{sub 4} ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best fitting bulk parameters, T{sub eff} = 1100K {+-} 100 and log(g) = 3.5 {+-} 0.5 (for solar composition). Given the observed luminosity (log L{sub obs}/L{sub {circle_dot}} {approx} -5.1), these values correspond to a radius of 0.75 R{sub Jup{sub 0.12}{sup +0.17}} and mass {approx} 0.72 M{sub Jup{sub -0.6}{sup +2.6}} - strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to {approx} 10 x that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (< 1000K) required by the evolution models.

  20. 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.

  1. The SOPHIE search for northern extrasolar planets. IX. Populating the brown dwarf desert

    NASA Astrophysics Data System (ADS)

    Wilson, P. A.; Hébrard, G.; Santos, N. C.; Sahlmann, J.; Montagnier, G.; Astudillo-Defru, N.; Boisse, I.; Bouchy, F.; Rey, J.; Arnold, L.; Bonfils, X.; Bourrier, V.; Courcol, B.; Deleuil, M.; Delfosse, X.; Díaz, , R. F.; Ehrenreich, D.; Forveille, T.; Moutou, C.; Pepe, F.; Santerne, A.; Ségransan, D.; Udry, S.

    2016-04-01

    Radial velocity planet search surveys of nearby solar-type stars have shown a strong scarcity of brown dwarf companions within ~5 AU. There is presently no comprehensive explanation for this lack of brown dwarf companions; therefore, increasing the sample of such objects is crucial to understand their formation and evolution. Based on precise radial velocities obtained using the SOPHIE spectrograph at Observatoire de Haute-Provence we characterise the orbital parameters of 15 companions to solar-type stars and constrain their true mass using astrometric data from the Hipparcos space mission. The nine companions not shown to be stellar in nature have minimum masses ranging from ~13 to 70 MJup, and are well distributed across the planet/brown dwarf mass regime, making them an important contribution to the known population of massive companions around solar-type stars. We characterise six companions as stellar in nature with masses ranging from a minimum mass of 76 ± 4 MJup to a mass of 0.35 ± 0.03 M⊙. The orbital parameters of two previously known substellar candidates are improved. 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.The radial velocity measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A144

  2. A Laboratory Demonstration of the Capability to Image an Earth-like Extrasolar Planet

    NASA Technical Reports Server (NTRS)

    Trauger, John T.; Wesley, A. Traub

    2007-01-01

    The detection and characterization of an Earth-like planet orbiting a nearby star requires a telescope with an extraordinarily large contrast at small angular separations. At visible wavelengths, an Earth-like planet would be 1 times 10-10 times fainter than the star at angular separations of typically 0.1 arcsecond or less. There are several proposed space telescope systems that could, in principle, achieve this. Here we report a laboratory experiment that reaches these limits. We have suppressed the diffracted and scattered light near a star-like source to a level of 6 times 10-10 times the peak intensity in individual coronagraph images. In a series of such images, together with simple image processing, we have effectively reduced this to a residual noise level of about 0.1 times 10-10. This demonstrates that a coronagraphic telescope in space could detect and spectroscopically characterize nearby exoplanetary systems, with the sensitivity to image an 'Earth-twin' orbiting a nearby star.

  3. Removing Activity-Related Radial Velocity Noise to Improve Extrasolar Planet Searches

    NASA Technical Reports Server (NTRS)

    Saar, Steven; Lindstrom, David M. (Technical Monitor)

    2004-01-01

    We have made significant progress towards the proposal goals of understanding the causes and effects of magnetic activity-induced radial velocity (v_r) jitter and developing methods for correcting it. In the process, we have also made some significant discoveries in the fields of planet-induced stellar activity, planet detection methods, M dwarf convection, starspot properties, and magnetic dynamo cycles. We have obtained super high resolution (R approximately 200,000), high S / N (greater than 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D coude. A long observing run in October 2002 in particular was quite successful (8 clear nights). We now have close to three years of data, which begins to sample a good fraction of the magnetic cycle timescales for some of our targets (e.g., kappa Ceti; P_cyc = 5.6 yrs). This will be very helpful in unraveling the complex relationships between plage and radial velocity (v-r) changes which we have uncovered. Preliminary analysis (Saar et al. 2003) of the data in hand, reveals correlations between median line bisector displacement and v_r. The correlation appears to be specific the the particular star being considered, probably since it is a function of both spectral type and rotation rate. Further analysis and interpretation will be in the context of evolving plage models and is in progress.

  4. Parent Stars of Extrasolar Planets. IV. 14 Herculis, HD 187123, and HD 210277

    NASA Astrophysics Data System (ADS)

    Gonzalez, Guillermo; Wallerstein, George; Saar, Steven H.

    1999-02-01

    Spectroscopic analyses of 14 Her, HD 187123, and HD 210277, recently reported to harbor planets, reveal that these stars are metal rich. We find [Fe/H]=0.50+/-0.05, 0.16+/-0.05, and 0.24+/-0.05 for 14 Her, HD 187123, and HD 210277, respectively. This is the first spectroscopic analysis of HD 187123; our results for 14 Her and HD 210277 are in agreement with published studies. It is shown that 14 Her and ρ1 Cnc are nearly identical in their bulk physical characteristics. This result, combined with their extreme metallicities, suggests that their physical parameters have been affected by the process that formed their planets. These two stars join a group of about half a dozen stars in the solar neighborhood with [Fe/H]>=0.4. It is also shown that 51 Peg and HD 187123, which have companions with similar orbital periods and masses, are nearly identical. We find vsini~2.0 km s-1 for HD 210277 from a high-resolution spectrum. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology, and the National Solar Observatory, Tucson, AZ, administered by AURA, Inc., for the NSF.

  5. ESA to test the smartest technique for detecting extrasolar planets from the ground

    NASA Astrophysics Data System (ADS)

    2002-03-01

    GENIE will use ESO's Very Large Telescopes Credits: European Southern Observatory This photo shows an aerial view of the observing platform on the top of Paranal mountain (from late 1999), with the four enclosu Three 1.8-m VLTI Auxiliary Telescopes (ATs) and paths of the light beams have been superposed on the photo. Also seen are some of the 30 'stations' where the ATs will be positioned for observations and from where the light beams from the telescopes can enter the Interferometric Tunnel below. The straight structures are supports for the rails on which the telescopes can move from one station to another. The Interferometric Laboratory (partly subterranean) is at the centre of the platform. How nulling interferometry works Credits: ESA 2002/Medialab How nulling interferometry works In nulling interferometry, light from a distant star (red beams) hits each telescope, labelled T1 and T2, simultaneously. Before the resultant light beams are combined, the beam from one telescope is delayed by half a wavelength. This means that when the rays are brought together, peaks from one telescope line up with troughs from the other and so are cancelled out (represented by the straight red line), leaving no starlight. Light from a planet (blue beams), orbiting the star, enters the telescopes at an angle. This introduces a delay in the light reaching the second telescope. So, even after the half wavelength change in one of the rays, when the beams are combined they are reinforced (represented by the large blue waves) rather than cancelled out. Illustration by Medialab. Nulling interferometry combines the signal from a number of different telescopes in such a way that the light from the central star is cancelled out, leaving the much fainter planet easier to see. This is possible because light is a wave with peaks and troughs. Usually when combining light from two or more telescopes, a technique called interferometry, the peaks are lined up with one another to boost the signal

  6. Deuterium Burning in Massive Giant Planets and Low-mass Brown Dwarfs Formed by Core-nucleated Accretion

    NASA Astrophysics Data System (ADS)

    Bodenheimer, Peter; D'Angelo, Gennaro; Lissauer, Jack J.; Fortney, Jonathan J.; Saumon, Didier

    2013-06-01

    Using detailed numerical simulations, we study the formation of bodies near the deuterium-burning limit according to the core-nucleated giant planet accretion scenario. The objects, with heavy-element cores in the range 5-30 M ⊕, are assumed to accrete gas up to final masses of 10-15 Jupiter masses (M Jup). After the formation process, which lasts 1-5 Myr and which ends with a "cold-start," low-entropy configuration, the bodies evolve at constant mass up to an age of several Gyr. Deuterium burning via proton capture is included in the calculation, and we determined the mass, M 50, above which more than 50% of the initial deuterium is burned. This often-quoted borderline between giant planets and brown dwarfs is found to depend only slightly on parameters, such as core mass, stellar mass, formation location, solid surface density in the protoplanetary disk, disk viscosity, and dust opacity. The values for M 50 fall in the range 11.6-13.6 M Jup, in agreement with previous determinations that do not take the formation process into account. For a given opacity law during the formation process, objects with higher core masses form more quickly. The result is higher entropy in the envelope at the completion of accretion, yielding lower values of M 50. For masses above M 50, during the deuterium-burning phase, objects expand and increase in luminosity by one to three orders of magnitude. Evolutionary tracks in the luminosity versus time diagram are compared with the observed position of the companion to Beta Pictoris.

  7. SHORT-DURATION LENSING EVENTS. I. WIDE-ORBIT PLANETS? FREE-FLOATING LOW-MASS OBJECTS? OR HIGH-VELOCITY STARS?

    SciTech Connect

    Di Stefano, Rosanne

    2012-08-01

    Short-duration lensing events tend to be generated by low-mass lenses or by lenses with high transverse velocities. Furthermore, for any given lens mass and speed, events of short duration are preferentially caused by nearby lenses (mesolenses) that can be studied in detail, or else by lenses so close to the source star that finite-source-size effects may be detected, yielding information about both the Einstein ring radius and the surface of the lensed star. Planets causing short-duration events may be in orbits with any orientation, and may have semimajor axes smaller than 1 AU, or they may reach the outer limits of their planetary systems, in the region corresponding to the solar system's Oort Cloud. They can have masses larger than Jupiter's or smaller than Pluto's. Lensing therefore has a unique potential to expand our understanding of planetary systems. A particular advantage of lensing is that it can provide precision measurements of system parameters, including the masses of and projected separation between star and planet. We demonstrate how the parameters can be extracted and show that a great deal can be learned. For example, it is remarkable that the gravitational mass of nearby free-floating planet-mass lenses can be measured by complementing observations of a photometric event with deep images that detect the planet itself. A fraction of short events may be caused by high-velocity stars located within a kiloparsec. Many high-velocity lenses are likely to be neutron stars that received large natal kicks. Other high-speed stars may be members of the halo population. Still others may be hypervelocity stars that have been ejected from the Galactic center, or runaway stars escaped from close binaries, possibly including the progenitor binaries of Type Ia supernovae.

  8. Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b. I. The Transit

    NASA Astrophysics Data System (ADS)

    McCullough, P. R.; Crouzet, N.; Deming, D.; Madhusudhan, N.

    2014-08-01

    We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 μm to 1.7 μm and spatially scanned the image across the detector at 2'' s-1. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 μm and 1.4 μm water vapor features are, respectively, 83 ± 53 ppm and 200 ± 47 ppm greater than the local minimum at 1.3 μm. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al., extending from 0.3 μm to 24 μm. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere, we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible, and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ~700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na I and K I at 0.589 μm and 0.769 μm to be weak.

  9. Water vapor in the spectrum of the extrasolar planet HD 189733b. I. The transit

    SciTech Connect

    McCullough, P. R.; Crouzet, N.; Deming, D.; Madhusudhan, N.

    2014-08-10

    We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 μm to 1.7 μm and spatially scanned the image across the detector at 2'' s{sup –1}. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 μm and 1.4 μm water vapor features are, respectively, 83 ± 53 ppm and 200 ± 47 ppm greater than the local minimum at 1.3 μm. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al., extending from 0.3 μm to 24 μm. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere, we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible, and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ∼700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na I and K I at 0.589 μm and 0.769 μm to be weak.

  10. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. II. DUST-INDUCED COLLISIONAL IONIZATION

    SciTech Connect

    Helling, Ch.; Jardine, M.; Mokler, F.

    2011-08-10

    Observations have shown that continuous radio emission and also sporadic H{alpha} and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These activity signatures are interpreted as being caused by coupling of an ionized atmosphere to the stellar magnetic field. What remains a puzzle, however, is the mechanism by which such a cool atmosphere can produce the necessary level of ionization. At these low temperatures, thermal gas processes are insufficient, but the formation of clouds sets in. Cloud particles can act as seeds for electron avalanches in streamers that ionize the ambient gas, and can lead to lightning and indirectly to magnetic field coupling, a combination of processes also expected for protoplanetary disks. However, the precondition is that the cloud particles are charged. We use results from DRIFT-PHOENIX model atmospheres to investigate collisional processes that can lead to the ionization of dust grains inside clouds. We show that ionization by turbulence-induced dust-dust collisions is the most efficient kinetic process. The efficiency is highest in the inner cloud where particles grow quickly and, hence, the dust-to-gas ratio is high. Dust-dust collisions alone are not sufficient to improve the magnetic coupling of the atmosphere inside the cloud layers, but the charges supplied either on grains or within the gas phase as separated electrons can trigger secondary nonlinear processes. Cosmic rays are likely to increase the global level of ionization, but their influence decreases if a strong, large-scale magnetic field is present as on brown dwarfs. We suggest that although thermal gas ionization declines in objects across the fully convective boundary, dust charging by collisional processes can play an important role in the lowest mass objects. The onset of atmospheric dust may therefore correlate with the anomalous X-ray and radio emission in atmospheres that are cool, but charged more than expected by pure

  11. Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Kirby, Kate; Babb, J.; Yoshino, K.

    2004-01-01

    In L-dwarfs and T-dwarfs the resonance lines of sodium and potassium are so profoundly pressure-broadened that their wings extend several hundred nanometers from line center. With accurate knowledge of the line profiles as a function of temperature and pressure: such lines can prove to be valuable diagnostics of the atmospheres of such objects. We have initiated a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Although potassium and sodium are the alkali species of most interest in the atmospheres of cool brown dwarfs and extrasolar giant planets, some of our theoretical focus this year has involved the calculation of pressure-broadening of lithium resonance lines by He, as a test of a newly developed suite of computer codes. In addition, theoretical calculations have been carried out to determine the leading long range van der Waals coefficients for the interactions of ground and excited alkali metal atoms with helium atoms, to within a probable error of 2%. Such data is important in determining the behavior of the resonance line profiles in the far wings. Important progress has been made on the experimental aspects of the program since the arrival of a postdoctoral fellow in September. A new absorption cell has been designed, which incorporates a number of technical improvements over the previous cell, including a larger cell diameter to enhance the signal, and fittings which allow for easier cleaning, thereby significantly reducing the instrument down-time.

  12. Ionization in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events

    SciTech Connect

    Bailey, R. L.; Helling, Ch.; Hodosán, G.; Bilger, C.; Stark, C. R.

    2014-03-20

    Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning) and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10{sup 8}-10{sup 10} m{sup 3}) than in a giant gas planet (10{sup 4}-10{sup 6} m{sup 3}). Our results suggest that the total dissipated energy in one event is <10{sup 12} J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH{sub 2} at the expense of CO and CH{sub 4}. Dust-forming molecules are destroyed and the cloud particle properties are frozen in unless enough time is available for complete evaporation. We summarize instruments potentially suitable to observe lightning on extrasolar objects.

  13. The University of Arizona Astronomy Club Observations of Transiting Extrasolar Planets TrES-3b and TrES-4b

    NASA Astrophysics Data System (ADS)

    Turner, Jake; Hardegree-Ullman, K.; Smart, B.; Walker-LaFollette, A.; Cunningham, K.; Hardegree-Ullman, E. E.; Crawford, B.; Mueting, J.; Carleton, T.; Schwarz, K.; Robertson, A.; Guvenen, B.; Towner, A.; Austin, C.; Henz, T.; Keys, D.; Johnson, K.

    2011-05-01

    Using the Steward Observatory 61" Kuiper Telescope, The University of Arizona Astronomy Club observed extrasolar planets TrES-3b and TrES-4b. We observed the planets with the Harris-B, V, and R filters as they transited their parent stars during the months of May-July 2009. The main goal of this project was to get undergraduates involved with a research astronomy project and allow them to gain experience beyond what they would receive in the classroom. Many of the team members were introduced to astronomical observing techniques and data reduction using IRAF. Part of the project involved determining the optimum number of flat-field and bias frames required for image calibrations. With our results, we have been able to confirm and refine previously published values for the planets' orbital inclination, mass, radius, and density.

  14. A Diffraction-limited Survey for Direct Detection of Halpha Emitting/Accreting ExtraSolar Planets with the 6.5m Magellan Telescope and the MagAO Visible AO system

    NASA Astrophysics Data System (ADS)

    Close, Laird

    steady diet of hydrogen gas. Such planets should then be quite bright in Halpha accretion emission. The key point is that: instead of a steep drop off in the luminosity of the planet’s atmosphere, the accretion luminosity of these planets will just linearly decrease with decreasing mass. At an accretion rate=6e-10 Msun/yr we find low mass (~1 Mjup) accreting gap planets are much (50-1000x) brighter (for 0-3.4 mag of Halpha extinction) in Halpha than at H band. PROOF-OF_CONCEPT: A 3 hour MagAO observation at Halpha of a transitional disk in April 2013 was made. The resulting deep diffraction-limited images discovered (at 10.5 sigma) an Halpha source that was 295% above the continuum just 0.083” from the star (edge of the inner 10 AU disk gap). We also detected (at 5 sigma) an excellent (though much fainter) ~1 Mjup mass Halpha planet candidate located auspiciously at the outer edge (145 AU) of the gap. If confirmed by our “second epoch” follow-up as common proper motion then this would be the lowest mass (~1 Mjup) planet ever imaged. SURVEY: Scaling off of this exciting success we propose to deeply image (120 min) all 14 nearby (D<250pc), bright (R<11 mag) , not edge-on (i<80 deg) , young (~5 Myr) transitional disks with MagAO simultaneously at Halpha and L’. In addition, we will use BrGamma instead of Halpha for 8 additional fainter (11planets accreting at 6e-10 Msun/yr in 3.4 mag of extinction at Halpha at, or past, 0.2” separations. Therefore, based on the theoretical prediction that the inner and outer gap planets should be >1 Mjup in mass, we integrate across our target list and find that, in the worst case of minimal masses (1+/-0.5 Mjup), and 3.4 mag extinction, at least seven ~1 Mjup planets should be discovered by this survey --meeting all three of our science goals above.

  15. Searching for Extra-solar Planets with a Diffraction-Limited Balloon Borne Telescope

    NASA Astrophysics Data System (ADS)

    Ford, H. C.; Petro, L. D.; Allen, R.; Bely, P.; Burrows, C. J.; Krist, J.; Rafal, M.; White, R. L.; Jaffe, W.; Le Poole, R.; Crocker, J.; Dopita, M. A.; Grindlay, J. E.

    1998-12-01

    Our goal is to fly a diffraction limited 2.5-m optical telescope and coronagraph on long duration balloon flights at an altitudes of 35 km above 99.99% of the Earth's atmosphere to search for Jupiter-like planets around nearby stars. Analysis of radiosonde data from Mauna Kea and the South Pole suggests that at optical wavelengths and altitudes above 20 km r0 will be much greater than 6 meters anywhere in the world. A telescope equipped with an ultra smooth mirror and/or adaptive optics and coronagraph would provide three orders of magnitude improvement over the coronagraph in the Advanced Camera for Surveys (to be installed in Hubble in May 2000), four orders of magnitude improvement over the HST WFPC-2 camera, and five orders of magnitude improvement over ground based telescopes. A 2.5-m telescope could detect Jupiters and Saturns around the brightest stars within 10 parsecs of the Earth. No present or planned HST instruments will have this capability. Before we can design, build, and fly high resolution telescopes, we must first understand the high altitude balloon environment in detail. We need to know the spatial and temporal spectrum of wavefront errors, and the differential wind forces that will act on the telescope. We must understand the balloon environment sufficiently well to be able to discharge waste heat without spoiling the local thermal environment. We will discuss the major issues for high altitude "site testing" and subsequent high-resolution observations.

  16. Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts? Results from the Herschel Debris and Dunes Surveys

    NASA Astrophysics Data System (ADS)

    Moro-Martín, A.; Marshall, J. P.; Kennedy, G.; Sibthorpe, B.; Matthews, B. C.; Eiroa, C.; Wyatt, M. C.; Lestrade, J.-F.; Maldonado, J.; Rodriguez, D.; Greaves, J. S.; Montesinos, B.; Mora, A.; Booth, M.; Duchêne, G.; Wilner, D.; Horner, J.

    2015-03-01

    The study of the planet-debris disk connection can shed light on the formation and evolution of planetary systems and may help “predict” the presence of planets around stars with certain disk characteristics. In preliminary analyses of subsamples of the Herschel DEBRIS and DUNES surveys, Wyatt et al. and Marshall et al. identified a tentative correlation between debris and the presence of low-mass planets. Here we use the cleanest possible sample out of these Herschel surveys to assess the presence of such a correlation, discarding stars without known ages, with ages \\lt 1 Gyr, and with binary companions \\lt 100 AU to rule out possible correlations due to effects other than planet presence. In our resulting subsample of 204 FGK stars, we do not find evidence that debris disks are more common or more dusty around stars harboring high-mass or low-mass planets compared to a control sample without identified planets. There is no evidence either that the characteristic dust temperature of the debris disks around planet-bearing stars is any different from that in debris disks without identified planets, nor that debris disks are more or less common (or more or less dusty) around stars harboring multiple planets compared to single-planet systems. Diverse dynamical histories may account for the lack of correlations. The data show a correlation between the presence of high-mass planets and stellar metallicity, but no correlation between the presence of low-mass planets or debris and stellar metallicity. Comparing the observed cumulative distribution of fractional luminosity to those expected from a Gaussian distribution in logarithmic scale, we find that a distribution centered on the solar system’s value fits the data well, while one centered at 10 times this value can be rejected. This is of interest in the context of future terrestrial planet detection and characterization because it indicates that there are good prospects for finding a large number of debris

  17. Planetary Companions to HD 12661, HD 92788, and HD 38529 and Variations in Keplerian Residuals of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Fischer, Debra A.; Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Frink, Sabine; Apps, Kevin

    2001-04-01

    Precision Doppler observations at the Lick and Keck observatories have revealed Keplerian velocity variations in the stars HD 12661, HD 92788, and HD 38529. HD 12661 (G6 V) has an orbital period of 252.7+/-2.7 days, velocity semiamplitude K=88.4+/-2.0 m s-1, and orbital eccentricity e=0.23+/-0.024. Adopting a stellar mass of 1.07 Msolar, we infer a companion mass of Msini=2.79 MJ and a semimajor axis of a=0.79 AU. HD 92788 (G5 V) has an orbital period of 326.7+/-3.2 days, velocity semiamplitude K=99.9+/-2.4, and orbital eccentricity e=0.30+/-0.06. The adopted stellar mass of 1.06 Msolar yields a companion mass of Msini=3.34 MJ and a semimajor axis of a=0.95 AU. HD 38529 (G4 IV) has an orbital period of 14.3+/-0.8 days, velocity semiamplitude K=53.8+/-2.0 m s-1, and eccentricity e=0.27+/-0.03. The stellar mass of 1.4 Msolar sets Msini=0.77 MJ, with a semimajor axis of a=0.13 AU for this companion. In addition to the 14.3 day periodicity, the velocity residuals for HD 38529 show curvature over the three years of observations. Based on a measurement of Ca II H and K emission, all three stars are chromospherically inactive. Based on both spectral synthesis modeling and narrowband photometry, HD 12661, HD 92788, and HD 38529 all appear to be metal-rich stars, reinforcing the correlation of high metallicity in the host stars of gas giant extrasolar planets. We examine the velocity residuals to the Keplerian fits for a subsample of 12 planet-bearing stars that have been observed longer than two years at the Lick Observatory. Five of the 12 (Ups Andromedae, τ Boo, 55 Cnc, HD 217107, and HD 38529) exhibit coherent variations in the residual velocities that are consistent with additional companions. Except for Upsilon Andromedae, the source of the velocity variation remains speculative pending completion of one full orbit. GJ 876 exhibits residual velocities with high rms scatter (24 m s-1), lacking identifiable coherence. The residual velocities for six of the 12 stars (51

  18. A New Search for Carbon Monoxide Absorption in the Transmission Spectrum of the Extrasolar Planet HD 209458b

    NASA Astrophysics Data System (ADS)

    Deming, Drake; Brown, Timothy M.; Charbonneau, David; Harrington, Joseph; Richardson, L. Jeremy

    2005-04-01

    We have revisited the search for carbon monoxide absorption features in transmission during the transit of the extrasolar planet HD 209458b. In 2002 August-September we acquired a total of 1077 high-resolution spectra (λ/δλ~25,000) in the K-band (2 μm) wavelength region using NIRSPEC on the Keck II telescope during three transits. These data are more numerous and of better quality than the data analyzed in an initial search by Brown et al. Our analysis achieves a sensitivity sufficient to test the degree of CO absorption in the first-overtone bands during transit on the basis of plausible models of the planetary atmosphere. We analyze our observations by comparison with theoretical tangent geometry absorption spectra, computed by adding height-invariant ad hoc temperature perturbations to the model atmosphere of Sudarsky et al. and by treating cloud height as an adjustable parameter. We do not detect CO absorption. The strong 2-0 R-branch lines between 4320 and 4330 cm-1 have depths during transit less than 1.6 parts in 104 in units of the stellar continuum (3 σ limit) at a spectral resolving power of 25,000. Our analysis indicates a weakening similar to that found in the case of sodium, suggesting that a general masking mechanism is at work in the planetary atmosphere. Under the interpretation that this masking is provided by high clouds, our analysis defines the maximum cloud-top pressure (i.e., minimum height) as a function of the model atmospheric temperature. For the relatively hot model used by Charbonneau et al. to interpret their sodium detection, our CO limit requires cloud tops at or above 3.3 mbar, and these clouds must be opaque at a wavelength of 2 μm. High clouds comprised of submicron-sized particles are already present in some models but may not provide sufficient opacity to account for our CO result. Cooler model atmospheres, having smaller atmospheric scale heights and lower CO mixing ratios, may alleviate this problem to some extent

  19. PLANETS AROUND LOW-MASS STARS (PALMS). I. A SUBSTELLAR COMPANION TO THE YOUNG M DWARF 1RXS J235133.3+312720

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Cieza, Lucas A.; Kraus, Adam L.; Shkolnik, Evgenya L.; Dupuy, Trent J.; Tamura, Motohide

    2012-07-10

    We report the discovery of a brown dwarf companion to the young M dwarf 1RXS J235133.3+312720 as part of a high contrast imaging search for planets around nearby young low-mass stars with Keck-II/NIRC2 and Subaru/HiCIAO. The 2.''4 ({approx}120 AU) pair is confirmed to be comoving from two epochs of high-resolution imaging. Follow-up low- and moderate-resolution near-infrared spectroscopy of 1RXS J2351+3127 B with IRTF/SpeX and Keck-II/OSIRIS reveals a spectral type of L0{sup +2}{sub -1}. The M2 primary star 1RXS J2351+3127 A exhibits X-ray and UV activity levels comparable to young moving group members with ages of {approx}10-100 Myr. UVW kinematics based the measured radial velocity of the primary and the system's photometric distance (50 {+-} 10 pc) indicate it is likely a member of the {approx}50-150 Myr AB Dor moving group. The near-infrared spectrum of 1RXS J2351+3127 B does not exhibit obvious signs of youth, but its H-band morphology shows subtle hints of intermediate surface gravity. The spectrum is also an excellent match to the {approx}200 Myr M9 brown dwarf LP 944-20. Assuming an age of 50-150 Myr, evolutionary models imply a mass of 32 {+-} 6 M{sub Jup} for the companion, making 1RXS J2351+3127 B the second lowest-mass member of the AB Dor moving group after the L4 companion CD-35 2722 B and one of the few benchmark brown dwarfs known at young ages.

  20. Planets around Low-mass Stars (PALMS). I. A Substellar Companion to the Young M Dwarf 1RXS J235133.3+312720

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.; Cieza, Lucas A.; Kraus, Adam L.; Tamura, Motohide

    2012-07-01

    We report the discovery of a brown dwarf companion to the young M dwarf 1RXS J235133.3+312720 as part of a high contrast imaging search for planets around nearby young low-mass stars with Keck-II/NIRC2 and Subaru/HiCIAO. The 2farcs4 (~120 AU) pair is confirmed to be comoving from two epochs of high-resolution imaging. Follow-up low- and moderate-resolution near-infrared spectroscopy of 1RXS J2351+3127 B with IRTF/SpeX and Keck-II/OSIRIS reveals a spectral type of L0+2 -1. The M2 primary star 1RXS J2351+3127 A exhibits X-ray and UV activity levels comparable to young moving group members with ages of ~10-100 Myr. UVW kinematics based the measured radial velocity of the primary and the system's photometric distance (50 ± 10 pc) indicate it is likely a member of the ~50-150 Myr AB Dor moving group. The near-infrared spectrum of 1RXS J2351+3127 B does not exhibit obvious signs of youth, but its H-band morphology shows subtle hints of intermediate surface gravity. The spectrum is also an excellent match to the ~200 Myr M9 brown dwarf LP 944-20. Assuming an age of 50-150 Myr, evolutionary models imply a mass of 32 ± 6 M Jup for the companion, making 1RXS J2351+3127 B the second lowest-mass member of the AB Dor moving group after the L4 companion CD-35 2722 B and one of the few benchmark brown dwarfs known at young ages. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  1. The Effect of Tidal Inflation Instability on the Mass and Dynamical Evolution of Extrasolar Planets with Ultrashort Periods

    NASA Astrophysics Data System (ADS)

    Gu, Pin-Gao; Lin, Douglas N. C.; Bodenheimer, Peter H.

    2003-05-01

    We investigate the possibility of substantial inflation of short-period Jupiter-mass planets, as a result of their internal tidal dissipation associated with the synchronization and circularization of their orbits. We employ the simplest prescription based on an equilibrium model with a constant lag angle for all components of the tide. We show the following: (1) In the low-eccentricity limit, the synchronization of the planets' spin with their mean motion is established before tidal dissipation can significantly modify their internal structure. (2) However, above a critical eccentricity, which is a function of the planets' semimajor axis, tidal dissipation of energy during the circularization process can induce planets to inflate in size before their eccentricity is damped. (3) For moderate eccentricities, the planets adjust to stable thermal equilibria in which the rate of their internal tidal dissipation is balanced by the enhanced radiative flux associated with their enlarged radii. (4) For sufficiently large eccentricities, the planets swell beyond two Jupiter radii and their internal degeneracy is partially lifted. Thereafter, their thermal equilibria become unstable and they undergo runaway inflation until their radii exceed the Roche radius. (5) We determine the necessary and sufficient condition for this tidal inflation instability. (6) These results are applied to study short-period planets. We show that for young Jupiter-mass planets, with a period of less than 3 days, an initial radius of about 2RJ, and an orbital eccentricity greater than 0.2, the energy dissipated during the circularization of their orbits is sufficiently intense and protracted to inflate their sizes up to their Roche radii. (7) We estimate the mass-loss rate, the asymptotic planetary masses, and the semimajor axes for various planetary initial orbital parameters. The possibility of gas overflow through both inner (L1) and outer (L2) Lagrangian points for the planets with short

  2. Systems level feasibility study for the detection of extra-solar planets. Volume 1: Infrared interferometer (IRIS) known as the Stanford Concept

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A sensor system for the direct detection of extrasolar planets from an Earth orbit is evaluated: a spinning, infrared interferometer (IRIS). It is shuttle deployed, free flying, requires no on-orbit assembly and no reservicing over a design life of five years. The sensor concept and the mission objectives are reviewed, and the performance characteristics of a baseline sensor for standard observation conditions are derived. A baseline sensor design is given and the enabling technology discussed. Cost and weight estimates are performed; and a schedule for an IRIS program including technology development and assessment of risk are given. Finally, the sensor is compared with the apodized visual telescope sensor (APOTS) proposed for the same mission. The major conclusions are: that with moderate to strong technology advances, particularly in the fields of long life cryogenics, dynamical control, mirror manufacturing, and optical alignment, the detection of a Jupiter like planet around a Sunlike star at a distance of 30 light years is feasible, with a 3 meter aperture and an observation time of 1 hour. By contrast, major and possibly unlikely breakthroughs in mirror technology are required for APOTS to match this performance.

  3. The effect of host star spectral energy distribution and ice-albedo feedback on the climate of extrasolar planets.

    PubMed

    Shields, Aomawa L; Meadows, Victoria S; Bitz, Cecilia M; Pierrehumbert, Raymond T; Joshi, Manoj M; Robinson, Tyler D

    2013-08-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. In this study, we explored this effect with a one-dimensional (1-D), line-by-line, radiative transfer model to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy balance climate model. A three-dimensional (3-D) general circulation model was also used to explore the atmosphere's response to changes in incoming stellar radiation, or instellation, and surface albedo. Using this hierarchy of models, we simulated planets covered by ocean, land, and water-ice of varying grain size, with incident radiation from stars of different spectral types. Terrestrial planets orbiting stars with higher near-UV radiation exhibited a stronger ice-albedo feedback. We found that ice extent was much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G-dwarf star at an equivalent flux distance, and that ice-covered conditions occurred on an F-dwarf planet with only a 2% reduction in instellation relative to the present instellation on Earth, assuming fixed CO(2) (present atmospheric level on Earth). A similar planet orbiting the Sun at an equivalent flux distance required an 8% reduction in instellation, while a planet orbiting an M-dwarf star required an additional 19% reduction in instellation to become ice-covered, equivalent to 73% of the modern solar constant. The reduction in instellation must be larger for planets orbiting cooler stars due in large part to the stronger absorption of longer-wavelength radiation by icy surfaces on these planets in addition to stronger absorption by water vapor and CO(2) in their atmospheres, which provides increased downwelling longwave radiation. Lowering the IR and visible-band surface ice and snow albedos for an M-dwarf planet increased the planet's climate stability against changes in instellation and slowed the descent into global ice

  4. SYSTEMIC: A TESTBED FOR CHARACTERIZING THE DETECTION OF EXTRASOLAR PLANETS. II. NUMERICAL APPROACHES TO THE TRANSIT TIMING INVERSE PROBLEM

    SciTech Connect

    Meschiari, Stefano; Laughlin, Gregory P.

    2010-07-20

    Transit timing variations (TTVs)-deviations from strict periodicity between successive passages of a transiting planet-can be used to probe the structure and dynamics of multiple-planet systems. In this paper, we examine prospects for numerically solving the so-called inverse problem, the determination of the orbital elements of a perturbing body from the TTVs it induces. We assume that the planetary systems under examination have a limited number of Doppler velocity measurements and show that a more extensive radial velocity (RV) characterization with precision comparable to the semi-amplitude of the perturber may remove degeneracies in the solution. We examine several configurations of interest, including (1) a prototypical non-resonant system, modeled after HD 40307 b and c, which contains multiple super-Earth-mass planets, (2) a hypothetical system containing a transiting giant planet with a terrestrial-mass companion trapped in low-order mean motion resonance, and (3) the HAT-P-13 system, in which forced precession by an outer perturbing body that is well characterized by Doppler RV measurements can give insight into the interior structure of a perturbing planet, and for which the determination of mutual inclination between the transiting planet and its perturber is a key issue.

  5. New light on dark stars. Red dwarfs, low-mass stars, brown dwarfs.

    NASA Astrophysics Data System (ADS)

    Reid, I. N.; Hawley, S. L.

    This book presents a comprehensive discussion of both the astrophysical structure of individual M dwarf and brown dwarf star, and their collective statistical properties as a Galactic stellar population. The first section of the book discusses M dwarfs and brown dwarfs as individual objects - their observational properties, formation, internal structure and atmospheres. The second section deals with M dwarfs from the Galactic perspective - the number of stars, their possible contribution to dark matter and the missing mass and their use as probes of the stellar populations that make up our Galaxy. Contents: (1) Astronomical concepts. (2) Basic observational properties of low-mass dwarfs. (3) The structure, formation and evolution of low-mass stars and brown dwarfs. (4) The photosphere. (5) Stellar activity. (6) A Galactic structure primer. (7) The stellar luminosity function. (8) The mass function. (9) Brown dwarfs: new light on dark stars. (10) Extrasolar planets. (11) M dwarfs in the Galactic halo. Appendix: The 8 parsec sample.

  6. Impact of ηEarth on the Capabilities of Affordable Space Missions to Detect Biosignatures on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Léger, Alain; Defrère, Denis; Malbet, Fabien; Labadie, Lucas; Absil, Olivier

    2015-08-01

    We present an analytic model to estimate the capabilities of space missions dedicated to the search for biosignatures in the atmosphere of rocky planets located in the habitable zone of nearby stars. Relations between performance and mission parameters, such as mirror diameter, distance to targets, and radius of planets, are obtained. Two types of instruments are considered: coronagraphs observing in the visible, and nulling interferometers in the thermal infrared. Missions considered are: single-pupil coronagraphs with a 2.4 m primary mirror, and formation-flying interferometers with 4 × 0.75 m collecting mirrors. The numbers of accessible planets are calculated as a function of ηEarth. When Kepler gives its final estimation for ηEarth, the model will permit a precise assessment of the potential of each instrument. Based on current estimations, ηEarth = 10% around FGK stars and 50% around M stars, the coronagraph could study in spectroscopy only ∼1.5 relevant planets, and the interferometer ∼14.0. These numbers are obtained under the major hypothesis that the exozodiacal light around the target stars is low enough for each instrument. In both cases, a prior detection of planets is assumed and a target list established. For the long-term future, building both types of spectroscopic instruments, and using them on the same targets, will be the optimal solution because they provide complementary information. But as a first affordable space mission, the interferometer looks the more promising in terms of biosignature harvest.

  7. THE LICK-CARNEGIE EXOPLANET SURVEY: A URANUS-MASS FOURTH PLANET FOR GJ 876 IN AN EXTRASOLAR LAPLACE CONFIGURATION

    SciTech Connect

    Rivera, Eugenio J.; Laughlin, Gregory; Vogt, Steven S.; Meschiari, Stefano; Haghighipour, Nader

    2010-08-10

    Continued radial velocity (RV) monitoring of the nearby M4V red dwarf star GJ 876 with Keck/High Resolution Echelle Spectrograph has revealed the presence of a Uranus-mass fourth planetary companion in the system. The new planet has a mean period of P{sub e} = 126.6 days (over the 12.6-year baseline of the RV observations), and a minimum mass of m{sub e} sin i{sub e} = 12.9 {+-} 1.7 M {sub +}. The detection of the new planet has been enabled by significant improvements to our RV data set for GJ 876. The data have been augmented by 36 new high-precision measurements taken over the past five years. In addition, the precision of all of the Doppler measurements have been significantly improved by the incorporation of a high signal-to-noise template spectrum for GJ 876 into the analysis pipeline. Implementation of the new template spectrum improves the internal rms errors for the velocity measurements taken during 1998-2005 from 4.1 m s{sup -1} to 2.5 m s{sup -1}. Self-consistent, N-body fits to the RV data set show that the four-planet system has an invariable plane with an inclination relative to the plane of the sky of i = 59.{sup 0}5. The fit is not significantly improved by the introduction of a mutual inclination between the planets 'b' and 'c', but the new data do confirm a non-zero eccentricity, e{sub d} = 0.207 {+-} 0.055 for the innermost planet, 'd'. In our best-fit coplanar model, the mass of the new component is m{sub e} = 14.6 {+-} 1.7 M {sub +}. Our best-fitting model places the new planet in a three-body resonance with the previously known giant planets (which have mean periods of P{sub c} = 30.4 and P{sub b} = 61.1 days). The critical argument, {psi}{sub Laplace} = {lambda} {sub c} - 3{lambda} {sub b} + 2{lambda} {sub e}, for the Laplace resonance librates with an amplitude of {Delta}{psi}{sub Laplace} = 40{sup 0} {+-} 13{sup 0} about {psi}{sub Laplace} = 0{sup 0}. Numerical integration indicates that the four-planet system is stable for at least a

  8. The Discovery of the Most Metal-rich White Dwarf: Composition of a Tidally Disrupted Extrasolar Dwarf Planet

    NASA Astrophysics Data System (ADS)

    Dufour, P.; Kilic, M.; Fontaine, G.; Bergeron, P.; Lachapelle, F.-R.; Kleinman, S. J.; Leggett, S. K.

    2010-08-01

    Cool white dwarf stars are usually found to have an outer atmosphere that is practically pure in hydrogen or helium. However, a small fraction have traces of heavy elements that must originate from the accretion of extrinsic material, most probably circumstellar matter. Upon examining thousands of Sloan Digital Sky Survey (SDSS) spectra, we discovered that the helium-atmosphere white dwarf SDSS J073842.56+183509.6 shows the most severe metal pollution ever seen in the outermost layers of such stars. We present here a quantitative analysis of this exciting star by combining high signal-to-noise ratio follow-up spectroscopic and photometric observations with model atmospheres and evolutionary models. We determine the global structural properties of our target star, as well as the abundances of the most significant pollutants in its atmosphere, i.e., H, O, Na, Mg, Si, Ca, and Fe. The relative abundances of these elements imply that the source of the accreted material has a composition similar to that of Bulk Earth. We also report the signature of a circumstellar disk revealed through a large infrared excess in JHK photometry. Combined with our inferred estimate of the mass of the accreted material, this strongly suggests that we are witnessing the remains of a tidally disrupted extrasolar body that was as large as Ceres.

  9. THE DISCOVERY OF THE MOST METAL-RICH WHITE DWARF: COMPOSITION OF A TIDALLY DISRUPTED EXTRASOLAR DWARF PLANET

    SciTech Connect

    Dufour, P.; Fontaine, G.; Bergeron, P.; Lachapelle, F.-R.; Kilic, M.; Kleinman, S. J.; Leggett, S. K.

    2010-08-10

    Cool white dwarf stars are usually found to have an outer atmosphere that is practically pure in hydrogen or helium. However, a small fraction have traces of heavy elements that must originate from the accretion of extrinsic material, most probably circumstellar matter. Upon examining thousands of Sloan Digital Sky Survey (SDSS) spectra, we discovered that the helium-atmosphere white dwarf SDSS J073842.56+183509.6 shows the most severe metal pollution ever seen in the outermost layers of such stars. We present here a quantitative analysis of this exciting star by combining high signal-to-noise ratio follow-up spectroscopic and photometric observations with model atmospheres and evolutionary models. We determine the global structural properties of our target star, as well as the abundances of the most significant pollutants in its atmosphere, i.e., H, O, Na, Mg, Si, Ca, and Fe. The relative abundances of these elements imply that the source of the accreted material has a composition similar to that of Bulk Earth. We also report the signature of a circumstellar disk revealed through a large infrared excess in JHK photometry. Combined with our inferred estimate of the mass of the accreted material, this strongly suggests that we are witnessing the remains of a tidally disrupted extrasolar body that was as large as Ceres.

  10. Atom Resonance Lines for Modeling Atmosphere: Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Hasan, Hashima (Technical Monitor); Kirby, K.; Babb, J.; Yoshino, K.

    2005-01-01

    We report on progress made in a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Accurate knowledge of the line profiles of Na and K as a function of temperature and pressure will allow such lines to serve as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar giant planets. A new experimental apparatus has been designed, built and tested over the past year, and we are poised to begin collecting data on the first system of interest, the potassium resonance lines perturbed by collisions with helium. On the theoretical front, calculations of line-broadening due to sodium collisions with helium are nearly complete, using accurate molecular potential energy curves and transition moments just recently computed for this system. In addition we have completed calculations of the three relevant potential energy curves and associated transition moments for K - He, using the MOLPRO quantum chemistry codes. Currently, calculations of the potential surfaces describing K-H2 are in progress.

  11. Direct imaging of extra-solar planets in star forming regions. Lessons learned from a false positive around IM Lupi

    NASA Astrophysics Data System (ADS)

    Mawet, D.; Absil, O.; Montagnier, G.; Riaud, P.; Surdej, J.; Ducourant, C.; Augereau, J.-C.; Röttinger, S.; Girard, J.; Krist, J.; Stapelfeldt, K.

    2012-08-01

    Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1-5 μm). Because of these practical limitations, our current observational aim at detecting and characterizing planets puts heavy constraints on target selection, observing strategies, data reduction, and follow-up. Most surveys so far have thus targeted young systems (1-100 Myr) to catch the putative remnant thermal radiation of giant planets, which peaks in the near-infrared. They also favor systems in the solar neighborhood (d < 80 pc), which eases angular resolution requirements but also ensures a good knowledge of the distance and proper motion, which are critical to secure the planet status, and enable subsequent characterization. Aims: Because of their youth, it is very tempting to target the nearby star forming regions, which are typically twice as far as the bulk of objects usually combed for planets by direct imaging. Probing these interesting reservoirs sets additional constraints that we review in this paper by presenting the planet search that we initiated in 2008 around the disk-bearing T Tauri star IM Lup, which is part of the Lupus star forming region (140-190 pc). Methods: We show and discuss why age determination, the choice of evolutionary model for both the central star and the planet, precise knowledge of the host star proper motion, relative or absolute (between different instruments) astrometric accuracy (including plate scale calibration), and patience are the key ingredients for exoplanet searches around more distant young stars. Results: Unfortunately, most of the time, precision and perseverance are not paying off: we discovered a candidate companion around IM Lup in 2008, which we report here to be an unbound background object. We nevertheless review in details the lessons learned from our endeavor, and

  12. CHARACTERIZING THE COOL KEPLER OBJECTS OF INTERESTS. NEW EFFECTIVE TEMPERATURES, METALLICITIES, MASSES, AND RADII OF LOW-MASS KEPLER PLANET-CANDIDATE HOST STARS

    SciTech Connect

    Muirhead, Philip S.; Hamren, Katherine; Schlawin, Everett; Lloyd, James P.; Rojas-Ayala, Barbara; Covey, Kevin R.

    2012-05-10

    We report stellar parameters for late-K and M-type planet-candidate host stars announced by the Kepler Mission. We obtained medium-resolution, K-band spectra of 84 cool (T{sub eff} {approx}< 4400 K) Kepler Objects of Interest (KOIs) from Borucki et al. We identified one object as a giant (KOI 977); for the remaining dwarfs, we measured effective temperatures (T{sub eff}) and metallicities [M/H] using the K-band spectral indices of Rojas-Ayala et al. We determine the masses (M{sub *}) and radii (R{sub *}) of the cool KOIs by interpolation onto the Dartmouth evolutionary isochrones. The resultant stellar radii are significantly less than the values reported in the Kepler Input Catalog and, by construction, correlate better with T{sub eff}. Applying the published KOI transit parameters to our stellar radius measurements, we report new physical radii for the planet candidates. Recalculating the equilibrium temperatures of the planet-candidates assuming Earth's albedo and re-radiation fraction, we find that three of the planet-candidates are terrestrial sized with orbital semimajor axes that lie within the habitable zones of their host stars (KOI 463.01, KOI 812.03, and KOI 854.01). The stellar parameters presented in this Letter serve as a resource for prioritization of future follow-up efforts to validate and characterize the cool KOI planet candidates.

  13. The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles

    NASA Astrophysics Data System (ADS)

    Díaz, R. F.; Ségransan, D.; Udry, S.; Lovis, C.; Pepe, F.; Dumusque, X.; Marmier, M.; Alonso, R.; Benz, W.; Bouchy, F.; Coffinet, A.; Collier Cameron, A.; Deleuil, M.; Figueira, P.; Gillon, M.; Lo Curto, G.; Mayor, M.; Mordasini, C.; Motalebi, F.; Moutou, C.; Pollacco, D.; Pompei, E.; Queloz, D.; Santos, N.; Wyttenbach, A.

    2016-01-01

    We present the analysis of the entire HARPS observations of three stars that host planetary systems: HD 1461, HD 40307, and HD 204313. The data set spans eight years and contains more than 200 nightly averaged velocity measurements for each star. This means that it is sensitive to both long-period and low-mass planets and also to the effects induced by stellar activity cycles. We modelled the data using Keplerian functions that correspond to planetary candidates and included the short- and long-term effects of magnetic activity. A Bayesian approach was taken both for the data modelling, which allowed us to include information from activity proxies such as log R'HK in the velocity modelling, and for the model selection, which permitted determining the number of significant signals in the system. The Bayesian model comparison overcomes the limitations inherent to the traditional periodogram analysis. We report an additional super-Earth planet in the HD 1461 system. Four out of the six planets previously reported for HD 40307 are confirmed and characterised. We discuss the remaining two proposed signals. In particular, we show that when the systematic uncertainty associated with the techniques for estimating model probabilities are taken into account, the current data are not conclusive concerning the existence of the habitable-zone candidate HD 40307 g. We also fully characterise the Neptune-mass planet that orbits HD 204313 in 34.9 days. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope at La Silla Observatory under the GTO programme ID 072.C-0488, and its continuation programmes ID 183.C-0972, 091.C-0936, and 192.C-0852.Full Tables 3, 6, and 10 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A134

  14. Photometric detections of secondary and primary transits of extra-solar planet CoRoT-1b

    NASA Astrophysics Data System (ADS)

    Gibson, Stephanie

    The goal of this project is to determine the observational limitations of photometrically detecting secondary eclipses of exoplanets from a 0.6-meter ground-based telescope and to place constraints on the planet's thermal properties. Secondary eclipses have been successfully measured via space-based telescopes such as the Spitzer Space Telescope. Time on space-based telescopes is limited and highly competitive. Smaller, ground-based telescopes are more common and thus it is easier for observers to schedule large blocks of time on these telescopes. These smaller telescopes also can observe exoplanets in the z' band on which the planets' thermal emission begins to become significant and would be more useful for building up large samples of data. A primary transit in B, V, and z' filters and a secondary transit in the z' filter of CoRoT-1b are analyzed in this thesis. Constraints on the planet's temperature, albedo and energy transports can be found from analysis of these transits.

  15. Light-curve analysis of KIC 12557548b: an extrasolar planet with a comet-like tail

    NASA Astrophysics Data System (ADS)

    Budaj, J.

    2014-03-01

    We will demonstrate how amateur observations with small telescopes of ε Aur (a bright eclipsing binary with the longest known orbital period) help to understand the nature of this object and how the understanding of physical processes in this object helps to understand superb Kepler observations of KIC 12557548b (an extremely short-period transiting exoplanet with a comet-like tail). We modified the code SHELLSPEC, which is designed for modelling interacting binary stars to calculate the light curves of such planets. Mie absorption and scattering on spherical dust grains with realistic dust opacities, phase functions, and a finite radius of the source of the scattered light are taken into account. We prove that the peculiar light curve of this exoplanet agrees with the idea of a planet with a comet-like tail. The light curve has a prominent pre-transit brightening and a less prominent post-transit brightening. Both are caused by the forward scattering and are a strong function of the particle size. This feature enabled us to estimate a typical particle size (radius) in the dust tail of about 0.1-1 μm. However, there is an indication that the particle size changes (decreases) along the tail. The dust density in the tail is a steep decreasing function of the distance from the planet, which indicates a significant tail destruction caused by the star-planet interaction. Several possible combinations of other dust properties are tabulated. We reveal interesting periodic long-term evolution of the tail on a time scale of about 1.3 years and also argue that the 'planet' does not show a uniform behaviour, but may have at least two constituents. This exoplanet's tail evolution may find an analogy in the comet tail disconnection events caused by the magnetic/coronal activity of the Sun while the light curve with pre-transit brightening is analogous to the light curve of ε Aur and AZ Cas with mid-eclipse brightening and forward scattering playing a significant role

  16. Kepler-539: A young extrasolar system with two giant planets on wide orbits and in gravitational interaction

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Lillo-Box, J.; Southworth, J.; Borsato, L.; Gandolfi, D.; Ciceri, S.; Barrado, D.; Brahm, R.; Henning, Th.

    2016-05-01

    We confirm the planetary nature of Kepler-539 b (aka Kepler object of interest K00372.01), a giant transiting exoplanet orbiting a solar-analogue G2 V star. The mass of Kepler-539 b was accurately derived thanks to a series of precise radial velocity measurements obtained with the CAFE spectrograph mounted on the CAHA 2.2-m telescope. A simultaneous fit of the radial-velocity data and Kepler photometry revealed that Kepler-539 b is a dense Jupiter-like planet with a mass of Mp = 0.97 ± 0.29 MJup and a radius of Rp = 0.747 ± 0.018 RJup, making a complete circular revolution around its parent star in 125.6 days. The semi-major axis of the orbit is roughly 0.5 au, implying that the planet is at ≈0.45 au from the habitable zone. By analysing the mid-transit times of the 12 transit events of Kepler-539 b recorded by the Kepler spacecraft, we found a clear modulated transit time variation (TTV), which is attributable to the presence of a planet c in a wider orbit. The few timings available do not allow us to precisely estimate the properties of Kepler-539 c and our analysis suggests that it has a mass between 1.2 and 3.6 MJup, revolving on a very eccentric orbit (0.4 planet c is the probable cause of the TTV modulation of planet b. The analysis of the CAFE spectra revealed a relatively high photospheric lithium content, A(Li) = 2.48 ± 0.12 dex, which, together with both a gyrochronological and isochronal analysis, suggests that the parent star is relatively young. RV/BVS measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A112

  17. The HARPS search for southern extra-solar planets. XXXIX. HD 175607, the most metal-poor G dwarf with an orbiting sub-Neptune

    NASA Astrophysics Data System (ADS)

    Mortier, A.; Faria, J. P.; Santos, N. C.; Rajpaul, V.; Figueira, P.; Boisse, I.; Collier Cameron, A.; Dumusque, X.; Lo Curto, G.; Lovis, C.; Mayor, M.; Melo, C.; Pepe, F.; Queloz, D.; Santerne, A.; Ségransan, D.; Sousa, S. G.; Sozzetti, A.; Udry, S.

    2016-01-01

    Context. The presence of a small-mass planet (Mp < 0.1 MJup) seems, to date, not to depend on metallicity, however, theoretical simulations have shown that stars with subsolar metallicities may be favoured for harbouring smaller planets. A large, dedicated survey of metal-poor stars with the HARPS spectrograph has thus been carried out to search for Neptunes and super-Earths. Aims: In this paper, we present the analysis of HD 175607, an old G6 star with metallicity [Fe/H] =-0.62. We gathered 119 radial velocity measurements in 110 nights over a time span of more than nine years. Methods: The radial velocities were analysed using Lomb-Scargle periodograms, a genetic algorithm, a Markov chain Monte Carlo analysis, and a Gaussian processes analysis. The spectra were also used to derive stellar properties. Several activity indicators were analysed to study the effect of stellar activity on the radial velocities. Results: We find evidence for the presence of a small Neptune-mass planet (Mpsini = 8.98 ± 1.10 M⊕) orbiting this star with an orbital period P = 29.01 ± 0.02 days in a slightly eccentric orbit (e = 0.11 ± 0.08). The period of this Neptune is close to the estimated rotational period of the star. However, from a detailed analysis of the radial velocities together with the stellar activity, we conclude that the best explanation of the signal is indeed the presence of a planetary companion rather than stellar related. An additional longer period signal (P ~ 1400 d) is present in the data, for which more measurements are needed to constrain its nature and its properties. Conclusions: HD 175607 is the most metal-poor FGK dwarf with a detected low-mass planet amongst the currently known planet hosts. This discovery may thus have important consequences for planet formation and evolution theories. Based on observations taken with the HARPS spectrograph (ESO 3.6-m telescope at La Silla) under programmes 072.C-0488(E), 082.C-0212(B), 085.C-0063(A), 086.C-0284(A

  18. A Search for Transiting Neptune-Mass Extrasolar Planets in High-Precision Photometry of Solar-Type Stars

    NASA Technical Reports Server (NTRS)

    Henry, Stephen M.; Gillman, Amelie r.; Henry, Gregory W.

    2005-01-01

    Tennessee State University operates several automatic photometric telescopes (APTs) at Fairborn Observatory in southern Arizona. Four 0.8 m APTs have been dedicated to measuring subtle luminosity variations that accompany magnetic cycles in solar-type stars. Over 1000 program and comparison stars have been observed every clear night in this program for up to 12 years with a precision of approximately 0.0015 mag for a single observation. We have developed a transit-search algorithm, based on fitting a computed transit template for each trial period, and have used it to search our photometric database for transits of unknown companions. Extensive simulations with the APT data have shown that we can reliably recover transits with periods under 10 days as long as the transits have a depth of at least 0.0024 mag, or about 1.6 times the scatter in the photometric observations. Thus, due to our high photometric precision, we are sensitive to transits of possible short-period Neptune-mass planets that likely would have escaped detection by current radial velocity techniques. Our search of the APT data sets for 1087 program and comparison stars revealed no new transiting planets. However, the detection of several unknown grazing eclipsing binaries from among our comparison stars, with eclipse depths of only a few millimags, illustrates the success of our technique. We have used this negative result to place limits on the frequency of Neptune-mass planets in close orbits around solar-type stars in the Sun's vicinity.

  19. Effect of planet ingestion on low-mass stars evolution: the case of 2MASS J08095427-4721419 star in the Gamma Velorum cluster

    NASA Astrophysics Data System (ADS)

    Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2016-08-01

    We analysed the effects of planet ingestion on the characteristics of a pre-MS star similar to the Gamma Velorum cluster member 2MASS J08095427--4721419 (#52). We discussed the effects of changing the age $t_0$ at which the accretion episode occurs, the mass of the ingested planet and its chemical composition. We showed that the mass of the ingested planet required to explain the current [Fe/H]^#52 increases by decreasing the age $t_0$ and/or by decreasing the Iron content of the accreted matter. We compared the predictions of a simplified accretion method -- where only the variation of the surface chemical composition is considered -- with that of a full accretion model that properly accounts for the modification of the stellar structure. We showed that the two approaches result in different convective envelope extension which can vary up to 10 percent. We discussed the impact of the planet ingestion on a stellar model in the colour-magnitude diagram, showing that a maximum shift of about 0.06 dex in the colour and 0.07 dex in magnitude are expected and that such variations persist even much later the accretion episode. We also analysed the systematic bias in the stellar mass and age inferred by using a grid of standard non accreting models to recover the characteristics of an accreting star. We found that standard non accreting models can safely be adopted for mass estimate, as the bias is <= 6 percent, while much more caution should be used for age estimate where the differences can reach about 60 percent.

  20. Effect of planet ingestion on low-mass stars evolution: the case of 2MASS J08095427-4721419 star in the Gamma Velorum cluster

    NASA Astrophysics Data System (ADS)

    Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2016-08-01

    We analysed the effects of planet ingestion on the characteristics of a pre-main-sequence star similar to the Gamma Velorum cluster member 2MASS J08095427-4721419 (#52). We discussed the effects of changing the age t0 at which the accretion episode occurs, the mass of the ingested planet and its chemical composition. We showed that the mass of the ingested planet required to explain the current [Fe/H]^{#52} increases by decreasing the age t0 and/or by decreasing the iron content of the accreted matter. We compared the predictions of a simplified accretion method - where only the variation of the surface chemical composition is considered - with that of a full accretion model that properly accounts for the modification of the stellar structure. We showed that the two approaches result in different convective envelope extension which can vary up to 10 per cent. We discussed the impact of the planet ingestion on a stellar model in the colour-magnitude diagram, showing that a maximum shift of about 0.06 dex in the colour and 0.07 dex in magnitude are expected and that such variations persist even much later the accretion episode. We also analysed the systematic bias in the stellar mass and age inferred by using a grid of standard non-accreting models to recover the characteristics of an accreting star. We found that standard non-accreting models can safely be adopted for mass estimate, as the bias is ≲ 6 per cent, while much more caution should be used for age estimate where the differences can reach about 60 per cent.

  1. THE FREQUENCY OF LOW-MASS EXOPLANETS

    SciTech Connect

    O'Toole, S. J.; Jones, H. R. A.; Tinney, C. G.; Bailey, J.; Wittenmyer, R. A.; Butler, R. P.; Marcy, G. W.; Carter, B.

    2009-08-20

    We report first results from the Anglo-Australian Telescope Rocky Planet Search-an intensive, high-precision Doppler planet search targeting low-mass exoplanets in contiguous 48 night observing blocks. On this run, we targeted 24 bright, nearby and intrinsically stable Sun-like stars selected from the Anglo-Australian Planet Search's main sample. These observations have already detected one low-mass planet reported elsewhere (HD 16417b), and here we reconfirm the detection of HD 4308b. Further, we have Monte Carlo simulated data from this run on a star-by-star basis to produce robust detection constraints. These simulations demonstrate clear differences in the exoplanet detectability functions from star to star due to differences in sampling, data quality and intrinsic stellar stability. They reinforce the importance of star-by-star simulation when interpreting the data from Doppler planet searches. These simulations indicate that for some of our target stars we are sensitive to close-orbiting planets as small as a few Earth masses. The two low-mass planets present in our 24-star sample indicate that the exoplanet minimum mass function at low masses is likely to be a flat {alpha} {approx} -1 (for dN/dM {proportional_to} M {sup {alpha}}) and that between 15% {+-} 10% (at {alpha} = -0.3) and 48% {+-} 34% (at {alpha} = -1.3) of stars host planets with orbital periods of less than 16 days and minimum masses greater than 3 M {sub +}.

  2. High-dispersion spectroscopy of extrasolar planets: from CO in hot Jupiters to O2 in exo-Earths.

    PubMed

    Snellen, Ignas

    2014-04-28

    Ground-based high-dispersion spectroscopy could reveal molecular oxygen as a biomarker gas in the atmospheres of twin-Earths transiting red dwarf stars within the next 25 years. The required contrasts are only a factor of 3 lower than that already achieved for carbon monoxide in hot Jupiter atmospheres today but will need much larger telescopes because the target stars will be orders of magnitude fainter. If extraterrestrial life is very common and can therefore be found on planets around the most nearby red dwarf stars, it may be detectable via transmission spectroscopy with the next-generation extremely large telescopes. However, it is likely that significantly more collecting area is required for this. This can be achieved through the development of low-cost flux collector technology, which combines a large collecting area with a low but sufficient image quality for high-dispersion spectroscopy of bright stars. PMID:24664914

  3. First Detection of a Dust Disk around Iota Horologii, a Southern Star Orbitted by an Extrasolar Giant Planet

    NASA Astrophysics Data System (ADS)

    Pantin, E.; Els, S.; Marchis, F.; Endl, M.; Kürster, M.; Sterzik, M.

    2000-12-01

    The link between the presence of debris dust disks (Vega phenomenon) and planetary formation is still unclear; are they: excluding children, siamese twins, or just casual neighbours? Recenly, Trilling et al. (1999), thanks to coronograph observations in the Northern hemisphere, showed that 3 out of 6 stars with known planetary companions harbour a tenuous dust disk, probably some precursors to the analogues of our Solar System Kuiper belt and zodiacal disk. We have started to conduct a similar program in the southern hemisphere at the ESO 3.6m telescope using the adaptive optics system ADONIS. H band images taken in coronographic mode during good observing conditions reveal the presence of a tenuous dust disk around the star Iota Horologii. This star is know to have a planetary companion of 2.26 M.sin i Jupiter masses on a 1 AU orbit, revealed by radial velocities analysis. The ADONIS images show that the disk has an inclination with a tilt angle of 40 degrees with respect to the edge-on configuration. This information allows to remove the degeneracy on the estimation of the mass of the planet due to the unknown inclination of the orbit. Taking this value into account, we find that the planet mass is 3.41 Jupiter masses. In our ADONIS observations, the disk extends 3.7 arcsec from the star, i.e. about 65 AU taking into account the distance of 17 parcsecs of this system. Modelling of light scattering by dust particles are shown and compared to the observations in order to deduce the disk density profile. This density profile is compared to previous results on disks around Beta Pic and HD 100546.

  4. 3.6 AND 4.5 {mu}m PHASE CURVES AND EVIDENCE FOR NON-EQUILIBRIUM CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HD 189733b

    SciTech Connect

    Knutson, Heather A.; Lewis, Nikole; Showman, Adam P.; Fortney, Jonathan J.; Laughlin, Gregory; Burrows, Adam; Cowan, Nicolas B.; Agol, Eric; Aigrain, Suzanne; Charbonneau, David; Desert, Jean-Michel; Deming, Drake; Henry, Gregory W.; Langton, Jonathan

    2012-07-20

    We present new, full-orbit observations of the infrared phase variations of the canonical hot Jupiter HD 189733b obtained in the 3.6 and 4.5 {mu}m bands using the Spitzer Space Telescope. When combined with previous phase curve observations at 8.0 and 24 {mu}m, these data allow us to characterize the exoplanet's emission spectrum as a function of planetary longitude and to search for local variations in its vertical thermal profile and atmospheric composition. We utilize an improved method for removing the effects of intrapixel sensitivity variations and robustly extracting phase curve signals from these data, and we calculate our best-fit parameters and uncertainties using a wavelet-based Markov Chain Monte Carlo analysis that accounts for the presence of time-correlated noise in our data. We measure a phase curve amplitude of 0.1242% {+-} 0.0061% in the 3.6 {mu}m band and 0.0982% {+-} 0.0089% in the 4.5 {mu}m band, corresponding to brightness temperature contrasts of 503 {+-} 21 K and 264 {+-} 24 K, respectively. We find that the times of minimum and maximum flux occur several hours earlier than predicted for an atmosphere in radiative equilibrium, consistent with the eastward advection of gas by an equatorial super-rotating jet. The locations of the flux minima in our new data differ from our previous observations at 8 {mu}m, and we present new evidence indicating that the flux minimum observed in the 8 {mu}m is likely caused by an overshooting effect in the 8 {mu}m array. We obtain improved estimates for HD 189733b's dayside planet-star flux ratio of 0.1466% {+-} 0.0040% in the 3.6 {mu}m band and 0.1787% {+-} 0.0038% in the 4.5 {mu}m band, corresponding to brightness temperatures of 1328 {+-} 11 K and 1192 {+-} 9 K, respectively; these are the most accurate secondary eclipse depths obtained to date for an extrasolar planet. We compare our new dayside and nightside spectra for HD 189733b to the predictions of one-dimensional radiative transfer models from

  5. MODELING THE INFRARED SPECTRUM OF THE EARTH-MOON SYSTEM: IMPLICATIONS FOR THE DETECTION AND CHARACTERIZATION OF EARTHLIKE EXTRASOLAR PLANETS AND THEIR MOONLIKE COMPANIONS

    SciTech Connect

    Robinson, Tyler D.

    2011-11-01

    The Moon maintains large surface temperatures on its illuminated hemisphere and can contribute significant amounts of flux to spatially unresolved thermal infrared (IR) observations of the Earth-Moon system, especially at wavelengths where Earth's atmosphere is absorbing. In this paper we investigate the effects of an unresolved companion on IR observations of Earthlike exoplanets. For an extrasolar twin Earth-Moon system observed at full phase at IR wavelengths, the Moon consistently comprises about 20% of the total signal, approaches 30% of the signal in the 9.6 {mu}m ozone band and the 15 {mu}m carbon dioxide band, makes up as much as 80% of the signal in the 6.3 {mu}m water band, and more than 90% of the signal in the 4.3 {mu}m carbon dioxide band. These excesses translate to inferred brightness temperatures for Earth that are too large by 20-40 K and demonstrate that the presence of undetected satellites can have significant impacts on the spectroscopic characterization of exoplanets. The thermal flux contribution from an airless companion depends strongly on phase, implying that observations of exoplanets should be taken when the star-planet-observer angle (i.e., phase angle) is as large as feasibly possible if contributions from companions are to be minimized. We show that, by differencing IR observations of an Earth twin with a companion taken at both gibbous and crescent phases, Moonlike satellites may be detectable by future exoplanet characterization missions for a wide range of system inclinations.

  6. CHEMICAL ABUNDANCES IN THE EXTERNALLY POLLUTED WHITE DWARF GD 40: EVIDENCE OF A ROCKY EXTRASOLAR MINOR PLANET

    SciTech Connect

    Klein, B.; Jura, M.; Zuckerman, B.; Melis, C.; Koester, D. E-mail: jura@astro.ucla.ed E-mail: cmelis@ucsd.ed

    2010-02-01

    We present Keck/High Resolution Echelle Spectrometer data with model atmosphere analysis of the helium-dominated polluted white dwarf GD 40, in which we measure atmospheric abundances relative to helium of nine elements: H, O, Mg, Si, Ca, Ti, Cr, Mn, and Fe. Apart from hydrogen, whose association with the other contaminants is uncertain, this material most likely accreted from GD 40's circumstellar dust disk whose existence is demonstrated by excess infrared emission. The data are best explained by accretion of rocky planetary material, in which heavy elements are largely contained within oxides, derived from a tidally disrupted minor planet at least the mass of Juno, and probably as massive as Vesta. The relatively low hydrogen abundance sets an upper limit of 10% water by mass in the inferred parent body, and the relatively high abundances of refractory elements, Ca and Ti, may indicate high-temperature processing. While the overall constitution of the parent body is similar to the bulk Earth being over 85% by mass composed of oxygen, magnesium, silicon, and iron, we find n(Si)/n(Mg) = 0.30 +- 0.11, significantly smaller than the ratio near unity for the bulk Earth, chondrites, the Sun, and nearby stars. This result suggests that differentiation occurred within the parent body.

  7. The SOPHIE search for northern extrasolar planets. XI. Three new companions and an orbit update: Giant planets in the habitable zone

    NASA Astrophysics Data System (ADS)

    Díaz, R. F.; Rey, J.; Demangeon, O.; Hébrard, G.; Boisse, I.; Arnold, L.; Astudillo-Defru, N.; Beuzit, J.-L.; Bonfils, X.; Borgniet, S.; Bouchy, F.; Bourrier, V.; Courcol, B.; Deleuil, M.; Delfosse, X.; Ehrenreich, D.; Forveille, T.; Lagrange, A.-M.; Mayor, M.; Moutou, C.; Pepe, F.; Queloz, D.; Santerne, A.; Santos, N. C.; Sahlmann, J.; Ségransan, D.; Udry, S.; Wilson, P. A.

    2016-07-01

    We report the discovery of three new substellar companions to solar-type stars, HD 191806, HD 214823, and HD 221585, based on radial velocity measurements obtained at the Haute-Provence Observatory. Data from the SOPHIE spectrograph are combined with observations acquired with its predecessor, ELODIE, to detect and characterise the orbital parameters of three new gaseous giant and brown dwarf candidates. Additionally, we combine SOPHIE data with velocities obtained at the Lick Observatory to improve the parameters of an already known giant planet companion, HD 16175 b. Thanks to the use of different instruments, the data sets of all four targets span more than ten years. Zero-point offsets between instruments are dealt with using Bayesian priors to incorporate the information we possess on the SOPHIE/ELODIE offset based on previous studies. The reported companions have orbital periods between three and five years and minimum masses between 1.6 MJup and 19 MJup. Additionally, we find that the star HD 191806 is experiencing a secular acceleration of over 11 m s-1 per year, potentially due to an additional stellar or substellar companion. A search for the astrometric signature of these companions was carried out using Hipparcos data. No orbit was detected, but a significant upper limit to the companion mass can be set for HD 221585, whose companion must be substellar. With the exception of HD 191806 b, the companions are located within the habitable zone of their host star. Therefore, satellites orbiting these objects could be a propitious place for life to develop. 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 (programme 07A.PNP.CONS to 15A.PNP.CONS).

  8. Barnard’s Star: Planets or Pretense

    NASA Astrophysics Data System (ADS)

    Bartlett, Jennifer L.; Ianna, P. A.

    2014-01-01

    Barnard’s Star remains popular with planet hunters because it is not only an extremely near, high proper motion star, but also the object of early planet-detection claims. In 1963, van de Kamp explained perturbations in its proper motion by the presence of a planet. In 1969, he produced another single-planet solution and a two-planet solution to the astrometric wobbles detected. At least 19 studies have failed to confirm his results using a range of techniques, including radial velocity, direct imaging, and speckle interferometry. However, most of them lacked the sensitivity to detect the planets he described, including astrometric studies at the McCormick and Naval Observatories. However, radial-velocity monitoring of Barnard’s Star at Lick and Keck Observatories from 1987 through 2012 appears to have ruled out such planets. Based upon observations made at the Sproul Observatory between 1916 and 1962, van de Kamp claimed that Barnard’s Star had a planet with about 1.6 times the mass of Jupiter and an orbital period of 24 years. After accounting for instrumentation effects that might have been partially responsible for his initial results, he continued to assert that this red dwarf had two planets. In his 1982 analysis of ~20,000 exposures collected between 1938 and 1981, he calculated that two planets with 0.7- and 0.5-Jupiter masses in 12- and 20-year orbits, respectively, orbited the second-closest stellar system to our own. Starting in 1995, the dramatic successes of radial velocity searches for extrasolar planets drove van de Kamp’s unsubstantiated claims from popular consciousness. Although many low-mass stellar companions were discovered through astrometry, the technique has been less successful for planets: “The Extrasolar Planets Encyclopaedia” identifies one such discovery out of the 997 planets listed on 2013 September 23. Although Barnard’s Star has lost its pretensions to hosting the first extrasolar planets known, its intrinsic

  9. Dust in brown dwarfs and extra-solar planets. I. Chemical composition and spectral appearance of quasi-static cloud layers

    NASA Astrophysics Data System (ADS)

    Helling, Ch.; Woitke, P.; Thi, W.-F.

    2008-07-01

    Aims: Brown dwarfs are covered by dust cloud layers which cause inhomogeneous surface features and move below the observable τ = 1 level during the object's evolution. The cloud layers have a strong influence on the structure and spectral appearance of brown dwarfs and extra-solar planets, e.g. by providing high local opacities and by removing condensable elements from the atmosphere causing a sub-solar metalicity in the atmosphere. We aim at understanding the formation of cloud layers in quasi-static substellar atmospheres that consist of dirty grains composed of numerous small islands of different solid condensates. Methods: The time-dependent description is a kinetic model describing nucleation, growth and evaporation. It is extended to treat gravitational settling and is applied to the static-stationary case of substellar model atmospheres. From the solution of the dust moments, we determine the grain size distribution function approximately which, together with the calculated material volume fractions, provides the basis for applying effective medium theory and Mie theory to calculate the opacities of the composite dust grains. Results: The cloud particles in brown dwarfs and hot giant-gas planets are found to be small in the high atmospheric layers (a ≈ 0.01 μm), and are composed of a rich mixture of all considered condensates, in particular MgSiO3[s], Mg2SiO4[s] and SiO2[s]. As the particles settle downward, they increase in size and reach several 100 μm in the deepest layers. The more volatile parts of the grains evaporate and the particles stepwise purify to form composite particles of high-temperature condensates in the deeper layers, mainly made of Fe[s] and Al2O3[s]. The gas phase abundances of the elements involved in the dust formation process vary by orders of magnitudes throughout the atmosphere. The grain size distribution is found to be relatively broad in the upper atmospheric layers but strongly peaked in the deeper layers. This reflects

  10. Extrasolar planetary systems.

    NASA Technical Reports Server (NTRS)

    Huang, S.-S.

    1973-01-01

    The terms 'planet' and 'planet-like objects' are defined. The observational search for extrasolar planetary systems is described, as performable by earthbound optical telescopes, by space probes, by long baseline radio interferometry, and finally by inference from the reception of signals sent by intelligent beings in other worlds. It is shown that any planetary system must be preceded by a rotating disk of gas and dust around a central mass. A brief review of the theories of the formation of the solar system is given, along with a proposed scheme for classification of these theories. The evidence for magnetic activity in the early stages of stellar evolution is presented. The magnetic braking theories of solar and stellar rotation are discussed, and an estimate is made for the frequency of occurrence of planetary systems in the universe.

  11. HIGH-PRECISION DYNAMICAL MASSES OF VERY LOW MASS BINARIES

    SciTech Connect

    Konopacky, Q. M.; Ghez, A. M.; McLean, I. S.; Barman, T. S.; Rice, E. L.; Bailey, J. I.; White, R. J.; Duchene, G. E-mail: ghez@astro.ucla.ed E-mail: barman@lowell.ed E-mail: white@chara.gsu.ed

    2010-03-10

    We present the results of a three year monitoring program of a sample of very low mass (VLM) field binaries using both astrometric and spectroscopic data obtained in conjunction with the laser guide star adaptive optics system on the W. M. Keck II 10 m telescope. Among the 24 systems studied, 15 have undergone sufficient orbital motion, allowing us to derive their relative orbital parameters and hence their total system mass. These measurements more than double the number of mass measurements for VLM objects, and include the most precise mass measurement to date (<2%). Among the 11 systems with both astrometric and spectroscopic measurements, six have sufficient radial velocity variations to allow us to obtain individual component masses. This is the first derivation of the component masses for five of these systems. Altogether, the orbital solutions of these low mass systems show a correlation between eccentricity and orbital period, consistent with their higher mass counterparts. In our primary analysis, we find that there are systematic discrepancies between our dynamical mass measurements and the predictions of theoretical evolutionary models (TUCSON and LYON) with both models either underpredicting or overpredicting the most precisely determined dynamical masses. These discrepancies are a function of spectral type, with late-M through mid-L systems tending to have their masses underpredicted, while one T-type system has its mass overpredicted. These discrepancies imply that either the temperatures predicted by evolutionary and atmosphere models are inconsistent for an object of a given mass, or the mass-radius relationship or cooling timescales predicted by the evolutionary models are incorrect. If these spectral-type trends are correct and hold into the planetary mass regime, the implication is that the masses of directly imaged extrasolar planets are overpredicted by the evolutionary models.

  12. Astrophysics: Growing planet brought to light

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaohuan

    2015-11-01

    Thousands of extrasolar planets have been discovered, but none is a planet in its infancy. Observations have finally been made of a young planet growing in its birthplace -- opening the way to many more such discoveries. See Letter p.342

  13. Extrasolar Planetary Transits

    NASA Astrophysics Data System (ADS)

    Cameron, Andrew Collier

    An extrasolar planet will transit the visible hemisphere of its host star if its orbital plane lies sufficiently close to the observer's line of sight. The resulting periodic dips in stellar flux reveal key system parameters, including the density of the host star and, if radial-velocity observations are available, the surface gravitational acceleration of the planet. In this chapter I present the essential methodology for modelling the time-dependent flux variation during a transit, and its use in determining the posterior probability distribution for the physical parameters of the system. Large-scale searches for transiting systems are an efficient way of discovering planets whose bulk densities, and hence compositions, can be accessed if their masses can also be determined. I present algorithms for detrending large ensembles of light curves, for searching for transit-like signals among them. I also discuss methods for identifying diluted stellar eclipsing binaries mimicking planetary transit signals, and validation of transit candidates too faint for radial-velocity follow-up. I review the use of time-resolved spectrophotometry and high-resolution spectroscopy during transits to identify the molecular constituents of exoplanetary atmospheres.

  14. Constraining the volatile fraction of planets from transit observations

    NASA Astrophysics Data System (ADS)

    Alibert, Y.

    2016-06-01

    Context. The determination of the abundance of volatiles in extrasolar planets is very important as it can provide constraints on transport in protoplanetary disks and on the formation location of planets. However, constraining the internal structure of low-mass planets from transit measurements is known to be a degenerate problem. Aims: Using planetary structure and evolution models, we show how observations of transiting planets can be used to constrain their internal composition, in particular the amount of volatiles in the planetary interior, and consequently the amount of gas (defined in this paper to be only H and He) that the planet harbors. We first explore planets that are located close enough to their star to have lost their gas envelope. We then concentrate on planets at larger distances and show that the observation of transiting planets at different evolutionary ages can provide statistical information on their internal composition, in particular on their volatile fraction. Methods: We computed the evolution of low-mass planets (super-Earths to Neptune-like) for different fractions of volatiles and gas. We used a four-layer model (core, silicate mantle, icy mantle, and gas envelope) and computed the internal structure of planets for different luminosities. With this internal structure model, we computed the internal and gravitational energy of planets, which was then used to derive the time evolution of the planet. Since the total energy of a planet depends on its heat capacity and density distribution and therefore on its composition, planets with different ice fractions have different evolution tracks. Results: We show for low-mass gas-poor planets that are located close to their central star that assuming evaporation has efficiently removed the entire gas envelope, it is possible to constrain the volatile fraction of close-in transiting planets. We illustrate this method on the example of 55 Cnc e and show that under the assumption of the absence of

  15. BENEFITS OF GROUND-BASED PHOTOMETRIC FOLLOW-UP FOR TRANSITING EXTRASOLAR PLANETS DISCOVERED WITH KEPLER AND CoRoT

    SciTech Connect

    Colon, Knicole D.; Ford, Eric B.

    2009-09-20

    Currently, over 40 transiting planets have been discovered by ground-based photometric surveys, and space-based missions such as Kepler and CoRoT are expected to detect hundreds more. Follow-up photometric observations from the ground will play an important role in constraining both orbital and physical parameters for newly discovered planets, especially those with small radii (R{sub p} {approx}< 4R{sub +}) and/or intermediate-to-long orbital periods (P{approx}> 30 days). Here, we simulate transit light curves (LCs) from Kepler-like photometry and ground-based observations in the near-infrared (NIR) to determine how jointly modeling space-based and ground-based LCs can improve measurements of the transit duration and planet-star radius ratio. We find that adding observations of at least one ground-based transit to space-based observations can significantly improve the accuracy for measuring the transit duration and planet-star radius ratio of small planets (R{sub p} {approx}< 4R{sub +}) in long-period ({approx}1 year) orbits, largely thanks to the reduced effect of limb darkening in the NIR. We also demonstrate that multiple ground-based observations are needed to gain a substantial improvement in the measurement accuracy for small planets with short orbital periods ({approx}3 days). Finally, we consider the role that higher ground-based precisions will play in constraining parameter measurements for typical Kepler targets. Our results can help inform the priorities of transit follow-up programs (including both primary and secondary transit of planets discovered with Kepler and CoRoT), leading to improved constraints for transit durations, planet sizes, and orbital eccentricities.

  16. Statistics of Low-Mass Companions to Stars: Implications for Their Origin

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Black, D. C.

    2001-01-01

    One of the more significant results from observational astronomy over the past few years has been the detection, primarily via radial velocity studies, of low-mass companions (LMCs) to solar-like stars. The commonly held interpretation of these is that the majority are "extrasolar planets" whereas the rest are brown dwarfs, the distinction made on the basis of apparent discontinuity in the distribution of M sin i for LMCs as revealed by a histogram. We report here results from statistical analysis of M sin i, as well as of the orbital elements data for available LMCs, to rest the assertion that the LMCs population is heterogeneous. The outcome is mixed. Solely on the basis of the distribution of M sin i a heterogeneous model is preferable. Overall, we find that a definitive statement asserting that LMCs population is heterogeneous is, at present, unjustified. In addition we compare statistics of LMCs with a comparable sample of stellar binaries. We find a remarkable statistical similarity between these two populations. This similarity coupled with marked populational dissimilarity between LMCs and acknowledged planets motivates us to suggest a common origin hypothesis for LMCs and stellar binaries as an alternative to the prevailing interpretation. We discuss merits of such a hypothesis and indicate a possible scenario for the formation of LMCs.

  17. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Astrophysics Data System (ADS)

    Clampin, Mark

    2009-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Exoplanet Probe mission to image and characterize extrasolar giant planets. EPIC will provide insights into the physical nature and architecture of a variety of planets in other solar systems. Initially, it will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses and characterize the atmospheres around A and F type stars which cannot be found with RV techniques. It will also observe the inner spatial structure of exozodiacal disks. EPIC has a heliocentric Earth trailing drift-away orbit, with a 5 year mission lifetime. The robust mission design is simple and flexible ensuring mission success while minimizing cost and risk. The science payload consists of a heritage optical telescope assembly (OTA), and visible nulling coronagraph (VNC) instrument. The instrument achieves a contrast ratio of 10^9 over a 5 arcsecond field-of-view with an unprecedented inner working angle of 0.13 arcseconds over the spectral range of 440-880 nm. The telescope is a 1.65 meter off-axis Cassegrain with an OTA wavefront error of lambda/9, which when coupled to the VNC greatly reduces the requirements on the large scale optics.

  18. Investigations on physics of planetary atmospheres and small bodies of the Solar system, extrasolar planets and disk structures around the stars

    NASA Astrophysics Data System (ADS)

    Vidmachenko, A. P.; Delets, O. S.; Dlugach, J. M.; Zakhozhay, O. V.; Kostogryz, N. M.; Krushevska, V. M.; Kuznyetsova, Y. G.; Morozhenko, O. V.; Nevodovskyi, P. V.; Ovsak, O. S.; Rozenbush, O. E.; Romanyuk, Ya. O.; Shavlovskiy, V. I.; Yanovitskij, E. G.

    2015-12-01

    The history and main becoming stages of Planetary system physics Department of the Main astronomical observatory of National academy of Sciences of Ukraine are considered. Fundamental subjects of department researches and science achievements of employees are presented. Fields of theoretical and experimental researches are Solar system planets and their satellites; vertical structures of planet atmospheres; radiative transfer in planet atmospheres; exoplanet systems of Milky Way; stars having disc structures; astronomical engineering. Employees of the department carry out spectral, photometrical and polarimetrical observations of Solar system planets, exoplanet systems and stars with disc structures. 1. From the history of department 2. The main directions of department research 3. Scientific instrumentation 4. Telescopes and observation stations 5. Theoretical studies 6. The results of observations of planets and small Solar system bodies and their interpretation 7. The study of exoplanets around the stars of our galaxy 8. Spectral energy distribution of fragmenting protostellar disks 9. Cooperation with the National Technical University of Ukraine (KPI) and National University of Ukraine "Lviv Polytechnic" to study the impact of stratospheric aerosol changes on weather and climate of the Earth 10. International relations. Scientific and organizational work. Scientific conferences, congresses, symposia 11. The main achievements of the department 12. Current researches 13. Anniversaries and awards

  19. The unstable CO2 feedback cycle on ocean planets

    NASA Astrophysics Data System (ADS)

    Kitzmann, Daniel; Alibert, Yann; Godolt, Mareike; Grenfell, John Lee; Heng, Kevin; Patzer, Beate; Rauer, Heike; Stracke, Barbara; von Paris, Philip

    2015-12-01

    Ocean planets are volatile rich planets, not present in our Solar System, which are dominated by deep, global oceans. Theoretical considerations and planet formation modeling studies suggest that extrasolar ocean planets should be a very common type of planet. One might therefore expect that low-mass ocean planets would be ideal candidates when searching for habitable exoplanets, since water is considered to be an essential requirement for life. However, a very large global ocean can also strongly influence the climate.The high pressure at the oceans bottom results in the formation of high-pressure water ice, separating the planetary crust from the liquid ocean and, thus, also from the atmosphere. In our study we, therefore, focus on the CO2 cycle between the atmosphere and the ocean which determines the atmospheric CO2 content. The atmospheric amount of CO2 is a fundamental quantity for assessing the potential habitability of the planet's surface because of its strong greenhouse effect, which determines the planetary surface temperature to a large degree.In contrast to the stabilising carbonate-silicate cycle regulating the long-term CO2 inventory of the Earth atmosphere, we find that the CO2 cycle on ocean planets is positive and has strong destabilising effects on the planetary climate. By using a chemistry model for oceanic CO2 dissolution and an atmospheric model for exoplanets, we show that the CO2 feedback cycle is severely limiting the potential habitability of ocean planets.

  20. Extrasolar-Refractory Dominated Planetesimals: An Assessment

    NASA Astrophysics Data System (ADS)

    Jura, Michael; Xu, S.

    2013-01-01

    While some extrasolar minor planets display enhanced abundances of refractory elements, the proposed existence of planetesimals that are composed mostly of oxygen, calcium and aluminum is not supported by published observations of about 60 externally-polluted white dwarfs. This result can be explained by invoking highly simplified conventional models of protoplanetary disks where refractory-dominated planetesimals only can form relatively close to the host star. Consequently, they are predicted to be engulfed and destroyed during the star's Asymptotic Giant Branch evolutionary phase, and do not survive except, perhaps, orbiting the most massive white dwarfs. The full range of extrasolar planetesimal compositions is still unknown.

  1. Formation, Habitability, and Detection of Extrasolar Moons

    PubMed Central

    Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Émeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I.

    2014-01-01

    Abstract The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1–0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology. Key Words: Astrobiology—Extrasolar planets—Habitability—Planetary science—Tides. Astrobiology 14, 798–835. PMID:25147963

  2. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Astrophysics Data System (ADS)

    Clampin, Mark; Melnick, Gary; Lyon, Richard; Kenyon, Scott; Sasselov, Dimitar; Tolls, Volker; Ford, Holland; Golimowski, David; Petro, Larry; Hartig, George; Sparks, William; Illingworth, Garth; Lin, Doug; Seager, Sara; Weinberger, Alycia; Harwit, Martin; Marley, Mark; Schneider, Jean; Shao, Michael; Levine, Marty; Ge, Jian; Woodruff, Robert

    2006-06-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F type stars which cannot be found with RV techniques, and observe the inner spatial structure and colors of debris disks. EPIC has a proposed launch date of 2012 to heliocentric Earth trailing drift-away orbit, with a 3 year mission lifetime (5 year goal), and will revisit planets at least three times at intervals of 9 months. The robust mission design is simple and flexible ensuring mission success while minimizing cost and risk. The science payload consists of a heritage optical telescope assembly (OTA), and visible nulling coronagraph (VNC) instrument. The instrument achieves a contrast ratio of 109 over a 4.84 arcsecond field-of-view with an unprecedented inner working angle of 0.14 arcseconds over the spectral range of 440-880 nm, with spectral resolutions from 10 - 150. The telescope is a 1.5 meter offaxis Cassegrain with an OTA wavefront error of λ/9, which when coupled to the VNC greatly reduces the requirements on the large scale optics, compressing them to stability requirements within the relatively compact VNC optical chain. The VNC features two integrated modular nullers, a spatial filter array (SFA), and an E2V-L3 photon counting CCD. Direct null control is accomplished from the science focal mitigating against complex wavefront and amplitude sensing and control strategies.

  3. The HARPS search for southern extra-solar planets. XXX. Planetary systems around stars with solar-like magnetic cycles and short-term activity variation

    NASA Astrophysics Data System (ADS)

    Dumusque, X.; Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bouchy, F.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Naef, D.

    2011-11-01

    We present the discovery of four new long-period planets within the HARPS high-precision sample: HD 137388b (Msini = 0.22 MJ), HD 204941b (Msini = 0.27 MJ), HD 7199b (Msini = 0.29 MJ), HD 7449b (Msini = 1.04 MJ). A long-period companion, probably a second planet, is also found orbiting HD 7449. Planets around HD 137388, HD 204941, and HD 7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD 7449b. All these planets were discovered even though their hosting stars have clear signs of activity. Solar-like magnetic cycles, characterized by long-term activity variations, can be seen for HD 137388, HD 204941 and HD 7199, whereas the measurements of HD 7449 reveal a short-term activity variation, most probably induced by magnetic features on the stellar surface. We confirm that magnetic cycles induce a long-term radial velocity variation and propose a method to reduce considerably the associated noise. The procedure consists of fitting the activity index and applying the same solution to the radial velocities because a linear correlation between the activity index and the radial velocity is found. Tested on HD 137388, HD 204941, and HD 7199, this correction reduces considerably the stellar noise induced by magnetic cycles and allows us to derive precisely the orbital parameters of planetary companions. Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory (Chile), under programme IDs 072.C-0488 and 183.C-0972.Radial velocities (Tables 4-7) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A55

  4. Progress of the Living with a Red Dwarf Program: Activity-Rotation-Age Relationships for M dwarfs and the Ages of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Engle, Scott G.; Guinan, Edward Francis; Harper, Graham

    2015-08-01

    Red Dwarfs (M dwarfs or dM stars) make up over 75% of the local stellar population. This is among the reasons they are being targeted by an increasing number of planet-hunting programs. As such, developing a method to accurately estimate the age of a field M dwarf is of critical importance. However, due to their long lifetimes and very slow nuclear evolution, the best method for determining ages is likely through “magnetic tracers” such as X-UV activity levels and stellar rotation rates. The Living with a Red Dwarf program’s database of M dwarfs with photometrically determined rotation periods (via starspot modulations) is becoming substantial. Its expansion to include M dwarfs with well-detached WD companions - through which reliable ages can be determined - has had significant impacts on the reliability of the relations. When combined with M dwarfs possessing cluster/population memberships, or specific kinematics, a full range of “calibrators” is being realized. We report on our continuing efforts to build reliable Activity-Rotation-Age relationships for M dwarfs, utilizing X-UV measures obtained with HST, IUE Chandra and XMM (both proposed by us, and archival). Such relationships permit the assessment of the habitability of planets hosted by red dwarfs, by delineating the X-UV radiation environments these planets are exposed to, and have been exposed to in the past. After proper calibration, the relationships can also permit the age of a field red dwarf (and any hosted planets) to be determined through measures of either the stellar rotation period or X-UV activity level.We gratefully acknowledge the support from NSF/RUI Grant AST 1009903, Chandra Grant GO-13200633, HST Grants GO-12124X and GO-13020X.

  5. 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.

  6. PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS

    SciTech Connect

    Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

    2009-07-10

    We study the final architecture of planetary systems that evolve under the combined effects of planet-planet and planetesimal scattering. Using N-body simulations we investigate the dynamics of marginally unstable systems of gas and ice giants both in isolation and when the planets form interior to a planetesimal belt. The unstable isolated systems evolve under planet-planet scattering to yield an eccentricity distribution that matches that observed for extrasolar planets. When planetesimals are included the outcome depends upon the total mass of the planets. For M {sub tot} {approx}> 1 M{sub J} the final eccentricity distribution remains broad, whereas for M {sub tot} {approx}< 1 M{sub J} a combination of divergent orbital evolution and recircularization of scattered planets results in a preponderance of nearly circular final orbits. We also study the fate of marginally stable multiple planet systems in the presence of planetesimal disks, and find that for high planet masses the majority of such systems evolve into resonance. A significant fraction leads to resonant chains that are planetary analogs of Jupiter's Galilean satellites. We predict that a transition from eccentric to near-circular orbits will be observed once extrasolar planet surveys detect sub-Jovian mass planets at orbital radii of a {approx_equal} 5-10 AU.

  7. Formation, Habitability, and Detection of Extrasolar Moons

    NASA Astrophysics Data System (ADS)

    Heller, René; Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Émeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I.

    2014-09-01

    The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology.

  8. Formation, habitability, and detection of extrasolar moons.

    PubMed

    Heller, René; Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Emeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I

    2014-09-01

    The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology. PMID:25147963

  9. The Earth as an extrasolar transiting planet. II. HARPS and UVES detection of water vapour, biogenic O2, and O3

    NASA Astrophysics Data System (ADS)

    Arnold, L.; Ehrenreich, D.; Vidal-Madjar, A.; Dumusque, X.; Nitschelm, C.; Querel, R. R.; Hedelt, P.; Berthier, J.; Lovis, C.; Moutou, C.; Ferlet, R.; Crooker, D.

    2014-04-01

    detected. Assuming no atmospheric perturbations, we show that the E-ELT is theoretically able to detect the O2A-band in 8 h of integration for an Earth twin at 10 pc. Conclusions: Biogenic O2, O3, and water vapour are detected in Earth observed as a transiting planet, and, in principle, would be within reach of the E-ELT for an Earth twin at 10 pc. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 086.C-0448.

  10. Building a virtual planet

    NASA Technical Reports Server (NTRS)

    Meadows, V. S.

    2002-01-01

    The virtual Planetary Laboratory (VPL) is a recently funded 5-yr project, which seeks toimprove our understanding of the range of plausible environments and the likely signatures for life on extrasolar terrestrial planets. To achieve these goals we are developing a suite of innovative modeling tools to simulate the environments and spectra of extrasolar planets. The core of the VPL IS a coupled radiative transfer/climate/chemistry model, which is augmented by interchangeable modules which characterize geological, exogenic, atmospheric escape, and life processes. The VPL is validated using data derived from terrestrial planets within our own solar system. The VPL will be used to explore the plausible range of atmospheric composittions and globally averaged spectra for extrasolar planets and for early Earth, and will improve our understanding of the effect of life on a planet's atmospheric spectrum and composition. The models will also be used to create a comprehensive spectral catalog to provide recommendations on the optimum wavelength range, spectral resolution, and instrument sensitivity required to characterize extrasolar terrestrial planets. Although developed by our team, the VPL is envisioned to be a comprehensive and flexible tool, which can be collaboratively used by the broader planetary science and astrobiology communities. This presentation will describe the project concept, the tasks involved, and will outline current progress to date. This work is funded by the NASA Astrobiology Institute.

  11. Witnessing Extrasolar Asteroid Destruction?

    NASA Astrophysics Data System (ADS)

    Xu, Siyi; Jura, Michael; Su, Kate; Meng, Huan

    2014-11-01

    40 white dwarfs with excess infrared radiation due to a circumstellar dust disk from tidally disrupted asteroids have been identified. Recently, we identified one dusty white dwarf whose infrared fluxes have been increasing since May 2014. Very likely, it is caused by a recent tidal disruption event of extrasolar asteroid. We propose DDT to follow it up in a timely manner because the flare could dissipate very soon. This proposal provides a unique opportunity to study the destruction of an extrasolar asteroid.

  12. Extreme Planets

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar called PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars. They spin and pulse with radiation, much like a lighthouse beacon. Here, the pulsar's twisted magnetic fields are highlighted by the blue glow.

    All three pulsar planets are shown in this picture; the farthest two from the pulsar (closest in this view) are about the size of Earth. Radiation from charged pulsar particles would probably rain down on the planets, causing their night skies to light up with auroras similar to our Northern Lights. One such aurora is illustrated on the planet at the bottom of the picture.

    Since this landmark discovery, more than 160 extrasolar planets have been observed around stars that are burning nuclear fuel. The planets spotted by Wolszczan are still the only ones around a dead star. They also might be part of a second generation of planets, the first having been destroyed when their star blew up. The Spitzer Space Telescope's discovery of a dusty disk around a pulsar might represent the beginnings of a similarly 'reborn' planetary system.

  13. Confirming the most water-rich extrasolar rocky body

    NASA Astrophysics Data System (ADS)

    Melis, Carl

    2014-10-01

    Most theories of exobiology require liquid water for a planet to be considered as habitable. Yet, very little is known about the prevalence of water for mature rocky objects in extrasolar planetary systems. A unique method of probing the existence, characteristics, and frequency of extrasolar water-bearing rocky bodies is through examining their bulk composition after they have been accreted by their host white dwarf star. Results to date show that water-rich extrasolar rocky bodies are rare. Evidence for oxygen in ground-based spectroscopy of SDSSJ104341.53+085558.2 suggests that it could be accreting the most water-rich extrasolar rocky object currently known. We propose COS ultraviolet spectroscopy to confirm the water-rich nature and characterize the mineralogy of the rocky body being accreted by this white dwarf star.

  14. Search for Low-mass Objects in the Globular Cluster M4. I. Detection of Variable Stars

    NASA Astrophysics Data System (ADS)

    Safonova, M.; Mkrtichian, D.; Hasan, P.; Sutaria, F.; Brosch, N.; Gorbikov, E.; Joseph, P.

    2016-02-01

    With every new discovery of an extrasolar planet, the absence of planets in globular clusters (GCs) becomes more and more conspicuous. Null detection of transiting hot Jupiters in GCs 47 Tuc, ω Cen, and NGC 6397 presents an important puzzle, raising questions about the role played by cluster metallicity and environment on formation and survival of planetary systems in densely populated stellar clusters. GCs were postulated to have many free-floating planets, for which microlensing (ML) is an established tool for detection. Dense environments, well-constrained distances and kinematics of lenses and sources, and photometry of thousands of stars simultaneously make GCs the ideal targets to search for ML. We present first results of a multisite, 69-night-long campaign to search for ML signatures of low-mass objects in the GC M4, which was chosen because of its proximity, location, and the actual existence of a planet. M4 was observed in R and I bands by two telescopes, 1 m T40 and 18-inch C18, of the Wise Observatory, Tel Aviv, Israel, from 2011 April to July. Observations on the 1 m telescope were carried out in service mode, gathering 12 to 48 20 s exposures per night for a total of 69 nights. C18 observations were done for about 4 hr a night for six nights in 2011 May. We employ a semiautomated pipeline to calibrate and reduce the images to the light curves that our group is developing for this purpose, which includes the differential photometry package DIAPL, written by Wozniak and modified by W. Pych. Several different diagnostics are employed for search of variability/transients. While no high-significance ML event was found in this observational run, we have detected more than 20 new variables and variable candidates in the M4 field, which we present here.

  15. Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

    PubMed

    Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

    2010-09-01

    The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life. PMID:20879864

  16. The Role of Tides in Known Multi-Planet Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The first known extrasolar planet system, upsilon Andromedae, was discovered in 1999. The number of stars known to possess more than one planet has been growing rapidly since then. The dynamical interactions among such planets can be quite strong. These interactions can excite the orbital eccentricities of planets, even planets orbiting very close to their stars. Stellar tides can damp the eccentricities of such close-in planets, removing dynamical energy from the system and ultimately affecting the motions of all of the planets. These and other effects of tides in extrasolar multi-planet systems will be discussed.

  17. Occultation Spectrophotometry of Extrasolar Planets with SOFIA

    NASA Astrophysics Data System (ADS)

    Angerhausen, Daniel; Huber, Klaus F.; Mandell, Avi M.; McElwain, Michael W.; Czesla, Stefan; Madhusudhan, Nikku; Morse, Jon A.

    2014-04-01

    The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), a 2.5-meter infrared telescope on board a Boeing 747-SP, will conduct 0.3 - 1,600 μm photometric, spectroscopic, and imaging observations from altitudes as high as 45,000 ft., where the average atmospheric transmission is greater than 80 percent. SOFIA's first light cameras and spectrometers, as well as future generations of instruments, will make important contributions to the characterization of the physical properties of exoplanets. Our analysis shows that optical and near-infrared photometric and spectrophotometric follow-up observations during planetary transits and eclipses will be feasible with SOFIA's instrumentation, in particular the HIPO-FLITECAM optical/NIR instruments. The airborne-based platform has unique advantages in comparison to ground- and space-based observatories in this field of research which we will outline here. Furthermore we will present two exemplary science cases, that will be conducted in SOFIA's cycle 1.

  18. Occultation Spectrophotometry of Extrasolar Planets with SOFIA

    NASA Technical Reports Server (NTRS)

    Angerhausen, Daniel; Huber, Klaus F.; Mandell, Avi M.; McElwain, Michael W.; Czesla, Stefan; Madhusudhan, Nikku

    2012-01-01

    The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), a 2.5- meter infrared telescope on board a Boeing 747-SP, will conduct 0.3 - 1,600 micrometer photometric, spectroscopic, and imaging observations from altitudes as high as 45,000 ft., where the average atmospheric transmission is greater than 80 percent. SOFIA's first light cameras and spectrometers, as well as future generations of instruments, will make important contributions to the characterization of the physical properties of exoplanets. Our analysis shows that optical and near-infrared photometric and spectrophotometric follow-up observations during planetary transits and eclipses will be feasible with SOFIA's instrumentation, in particular the HIPOFLITECAM optical/NIR instruments. The airborne-based platform has unique advantages in comparison to ground- and space-based observatories in this field of research which we will outline here. Furthermore we will present two exemplary science cases, that will be conducted in SOFIA's cycle 1.

  19. MAGNETICALLY CONTROLLED CIRCULATION ON HOT EXTRASOLAR PLANETS

    SciTech Connect

    Batygin, Konstantin; Stanley, Sabine; Stevenson, David J.

    2013-10-10

    Through the process of thermal ionization, intense stellar irradiation renders hot Jupiter atmospheres electrically conductive. Simultaneously, lateral variability in the irradiation drives the global circulation with peak wind speeds of the order of ∼km s{sup –1}. In turn, the interactions between the atmospheric flows and the background magnetic field give rise to Lorentz forces that can act to perturb the flow away from its purely hydrodynamical counterpart. Using analytical theory and numerical simulations, we show here that significant deviations away from axisymmetric circulation are unstable in presence of a non-negligible axisymmetric magnetic field. Specifically, our results suggest that dayside-to-nightside flows, often obtained within the context of three-dimensional circulation models, only exist on objects with anomalously low magnetic fields, while the majority of highly irradiated exoplanetary atmospheres are entirely dominated by zonal jets.

  20. Proceedings of Protostars and Planets V

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Oral presentation sessions in this conference include: Clouds and cores; Star formation and protostars; Binaries and multiples; Newborn massive stars; jets and outflows; Clusters and associations; T Tauri stars and disks; Brown dwarfs; Planet formation and evolution; Extrasolar planets; Dust and protoplanetary disks; Early solar system and Astrobiology. Poster presentations included: Clouds and Cores. Collapse and Protostars, Binaries and Multiples, Clusters, Associations, and the IMF, Jets and Outflows, T Tauri Stars and Other Young Stars, Disks and Disk Accretion, Brown Dwarfs, Herbig Ae/Be Stars and Massive Stars, Solar System Objects, Planet Formation, Extrasolar Planets and Planet Detection, Properties of Protoplanetary Disks, Migration and Planetary Orbits and Meteoritics and Astrobiology

  1. Planet Formation

    NASA Astrophysics Data System (ADS)

    Klahr, Hubert; Brandner, Wolfgang

    2011-02-01

    1. Historical notes on planet formation Bodenheimer; 2. The formation and evolution of planetary systems Bouwman et al.; 3. Destruction of protoplanetary disks by photoevaporation Richling, Hollenbach and Yorke; 4. Turbulence in protoplanetary accretion disks Klahr, Rozyczka, Dziourkevitch, Wunsch and Johansen; 5. The origin of solids in the early solar system Trieloff and Palme; 6. Experiments on planetesimal formation Wurm and Blum; 7. Dust coagulation in protoplanetary disks Henning, Dullemond, Wolf and Dominik; 8. The accretion of giant planet cores Thommes and Duncan; 9. Planetary transits: direct vision of extrasolar planets Lecavelier des Etangs and Vidal-Madjar; 10. The core accretion - gas capture model Hubickyj; 11. Properties of exoplanets Marcy, Fischer, Butler and Vogt; 12. Giant planet formation: theories meet observations Boss; 13. From hot Jupiters to hot Neptures … and below Lovis, Mayor and Udry; 14. Disk-planet interaction and migration Masset and Kley; 15. The Brown Dwarf - planet relation Bate; 16. From astronomy to astrobiology Brandner; 17. Overview and prospective Lin.

  2. Orbits and Interiors of Planets

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin

    2012-05-01

    The focus of this thesis is a collection of problems of timely interest in orbital dynamics and interior structure of planetary bodies. The first three chapters are dedicated to understanding the interior structure of close-in, gaseous extrasolar planets (hot Jupiters). In order to resolve a long-standing problem of anomalously large hot Jupiter radii, we proposed a novel magnetohydrodynamic mechanism responsible for inflation. The mechanism relies on the electro-magnetic interactions between fast atmospheric flows and the planetary magnetic field in a thermally ionized atmosphere, to induce electrical currents that flow throughout the planet. The resulting Ohmic dissipation acts to maintain the interior entropies, and by extension the radii of hot Jupiters at an enhanced level. Using self-consistent calculations of thermal evolution of hot Jupiters under Ohmic dissipation, we demonstrated a clear tendency towards inflated radii for effective temperatures that give rise to significant ionization of K and Na in the atmosphere, a trend fully consistent with the observational data. Furthermore, we found that in absence of massive cores, low-mass hot Jupiters can over-flow their Roche-lobes and evaporate on Gyr time-scales, possibly leaving behind small rocky cores. Chapters four through six focus on the improvement and implications of a model for orbital evolution of the solar system, driven by dynamical instability (termed the "Nice" model). Hydrodynamical studies of the orbital evolution of planets embedded in protoplanetary disks suggest that giant planets have a tendency to assemble into multi-resonant configurations. Following this argument, we used analytical methods as well as self-consistent numerical N-body simulations to identify fully-resonant primordial states of the outer solar system, whose dynamical evolutions give rise to orbital architectures that resemble the current solar system. We found a total of only eight such initial conditions, providing

  3. Winds from Low Mass Protostars

    NASA Astrophysics Data System (ADS)

    Shu, Frank H.; Lizano, Susana; Adams, Fred C.; Ruden, Steven P.

    In its last stages, star formation in molecular clouds includes the onset of a stellar wind that helps to clear away the surrounding placenta of gas and dust, thereby making the young stellar object optically visible. The authors discuss new observational evidence that the emerging wind is largely neutral and atomic in low-mass protostars. They then suggest a simple theoretical mechanism for the generation of such powerful neutral winds.

  4. Extrasolar Refractory-dominated Planetesimals: An Assessment

    NASA Astrophysics Data System (ADS)

    Jura, M.; Xu, S.

    2013-02-01

    Previously published observations of 60 externally polluted white dwarfs show that none of the stars have accreted from intact refractory-dominated parent bodies composed mainly of Al, Ca, and O, although planetesimals with such a distinctive composition have been predicted to form. We propose that such remarkable objects are not detected by themselves because, unless they are scattered outward from their initial orbit, they are engulfed and destroyed during the star's asymptotic giant branch evolution. As yet, there is at most only weak evidence supporting a scenario where the composition of any extrasolar minor planet can be explained by blending of an outwardly scattered refractory-dominated planetesimal with an ambient asteroid.

  5. EXTRASOLAR REFRACTORY-DOMINATED PLANETESIMALS: AN ASSESSMENT

    SciTech Connect

    Jura, M.; Xu, S. E-mail: sxu@astro.ucla.edu

    2013-02-01

    Previously published observations of 60 externally polluted white dwarfs show that none of the stars have accreted from intact refractory-dominated parent bodies composed mainly of Al, Ca, and O, although planetesimals with such a distinctive composition have been predicted to form. We propose that such remarkable objects are not detected by themselves because, unless they are scattered outward from their initial orbit, they are engulfed and destroyed during the star's asymptotic giant branch evolution. As yet, there is at most only weak evidence supporting a scenario where the composition of any extrasolar minor planet can be explained by blending of an outwardly scattered refractory-dominated planetesimal with an ambient asteroid.

  6. Discovery of Low Mass Binary with Super Jupiter Companion

    NASA Astrophysics Data System (ADS)

    Anthes Rich, Evan; Wisniewski, John P.; Hashimoto, Jun; Brandt, Timothy; Kuzuhara, Masayuki; Tamura, Motohide

    2015-12-01

    Transit and radial velocity surveys have been prolific in detecting ~2000 confirmed planets to date. While few directly imaged planets have detected, such systems provide a unique scientific opportunity to probe exoplanets at larger angular separation, younger ages, and study their atmospheres. We present new L- and M-band AO observations, obtained with IRCS on Subaru, of a super Jupiter companion orbiting a cool dwarf. We show that the central object is likely a binary, thereby making this system the first likely directly imaged planetary mass companion surrounding a low mass binary system.

  7. 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.

  8. Revealing the Chamaeleon: Young, low-mass stars surrounding eta and epsilon Chamaeleontis

    NASA Astrophysics Data System (ADS)

    Murphy, S. J.

    2012-01-01

    The deep southern sky surrounding the Chamaeleon dark clouds is abundant with pre-main sequence stars of various ages. Because of their youth (5-10 Myr) and proximity (d~100 pc), members of the open cluster eta Chamaeleontis and the nearby epsilon Chamaeleontis Association are ideal laboratories to study the formation and evolution of extrasolar planetary systems. To better understand their role as potential planet hosts, this thesis explores the formation, dynamical evolution, accretion and disk properties of both groups' low-mass members. The notable lack of low-mass stars in the young open cluster eta Cha has long been puzzling. Two possible explanations have been suggested; a top-heavy initial mass function or dynamical evolution, which preferentially ejected the low-mass members. Previous efforts to find these stars several degrees from the cluster core have been unsuccessful. By undertaking a wider (95 sq deg) photometric and proper motion survey with extensive follow-up spectroscopy, we have identified eight low-mass stars that were ejected from eta Cha over the past 5-10 Myr. Comparison with recent simulations shows our results are consistent with a dynamical origin for the current configuration of the cluster, without the need to invoke an initial mass function deficient in low-mass objects. Two of the dispersed members exhibited strong, variable H-alpha emission during our observations, including a star which had an event suggestive of accretion from a circumstellar disk. New infrared photometry confirms the presence of the disk. This star demonstrates that infrequent, episodic accretion can continue at low levels long after most disks around `old' pre-main sequence stars have dissipated. Another two confirmed non-members are slightly older than the cluster, but are only 42 arcseconds apart and share similar kinematics and distances. We show that they almost certainly form a wide (4000-6000 AU) ~10 Myr-old binary at 100-150 pc. The system is one of the

  9. Biases In A Magnitude Limited Versus A Distant Limited Planet Search

    NASA Technical Reports Server (NTRS)

    Koch, David; Borucki, William; Witteborn, Fred C. (Technical Monitor)

    1996-01-01

    All methods utilized to conduct a search or survey inevitably have some built-in biases. These biases are often traced to some limitation of the instrument used or some inherent character of the signal being recorded. We address these limitations for various methods used or proposed for planet detection: spectroscopy, astrometry, interferometry, and photometry. For spectroscopy, the turbulence in the photosphere limits the minimum measurable dossier velocity to 3 m/s and hence the minimum planet to star mass ratio, thereby favoring massive close-in planets. Limited available observing time will necessarily introduce additional selection biases in the targets observed and telescope aperture will limit the faintest magnitude stars to be measured; For astrometry, the angular resolution of the instrument along with motions in the photometric center of the star limit the furthest distance for which giant planets can be detected to about 10 pc and favor massive outer orbit planets around low mass non-solar like stars; For imaging interferometry, the minimum angular size of the central null limits both the distance to the star and closeness of the planet to the host star to about 1 AU at 10 pc and thus to the very few solar-like stars within 10 pc. Solar and extra-solar zodiacal emission will limit the minimum size of the detectable planet. For photometry, the inherent variability of the star does not limit the minimum planet size until earth-sized or smaller planets are considered around solar-like stars. The telescope aperture limits the faintest stars that can be monitored. As with spectroscopy, there is no inherent distant limit to the method. After addressing the limiting factors of each method, an estimate is made of the number of planets of various sizes that could be found for each stellar type based on the detection probability and the number of stars that can be searched for planets.

  10. Search for low-mass exoplanets by gravitational microlensing at high magnification.

    PubMed

    Abe, F; Bennett, D P; Bond, I A; Eguchi, S; Furuta, Y; Hearnshaw, J B; Kamiya, K; Kilmartin, P M; Kurata, Y; Masuda, K; Matsubara, Y; Muraki, Y; Noda, S; Okajima, K; Rakich, A; Rattenbury, N J; Sako, T; Sekiguchi, T; Sullivan, D J; Sumi, T; Tristram, P J; Yanagisawa, T; Yock, P C M; Gal-Yam, A; Lipkin, Y; Maoz, D; Ofek, E O; Udalski, A; Szewczyk, O; Zebrun, K; Soszynski, I; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L

    2004-08-27

    Observations of the gravitational microlensing event MOA 2003-BLG-32/OGLE 2003-BLG-219 are presented, for which the peak magnification was over 500, the highest yet reported. Continuous observations around the peak enabled a sensitive search for planets orbiting the lens star. No planets were detected. Planets 1.3 times heavier than Earth were excluded from more than 50% of the projected annular region from approximately 2.3 to 3.6 astronomical units surrounding the lens star, Uranus-mass planets were excluded from 0.9 to 8.7 astronomical units, and planets 1.3 times heavier than Saturn were excluded from 0.2 to 60 astronomical units. These are the largest regions of sensitivity yet achieved in searches for extrasolar planets orbiting any star. PMID:15333833

  11. Gemini Planet Imager: Preliminary Design Report

    SciTech Connect

    Macintosh, B

    2007-05-10

    For the first time in history, direct and indirect detection techniques have enabled the exploration of the environments of nearby stars on scales comparable to the size of our solar system. Precision Doppler measurements have led to the discovery of the first extrasolar planets, while high-contrast imaging has revealed new classes of objects including dusty circumstellar debris disks and brown dwarfs. The ability to recover spectrophotometry for a handful of transiting exoplanets through secondary-eclipse measurements has allowed us to begin to study exoplanets as individual entities rather than points on a mass/semi-major-axis diagram and led to new models of planetary atmospheres and interiors, even though such measurements are only available at low SNR and for a handful of planets that are automatically those most modified by their parent star. These discoveries have galvanized public interest in science and technology and have led to profound new insights into the formation and evolution of planetary systems, and they have set the stage for the next steps--direct detection and characterization of extrasolar Jovian planets with instruments such as the Gemini Planet Imager (GPI). As discussed in Volume 1, the ability to directly detect Jovian planets opens up new regions of extrasolar planet phase space that in turn will inform our understanding of the processes through which these systems form, while near-IR spectra will advance our understanding of planetary physics. Studies of circumstellar debris disks using GPI's polarimetric mode will trace the presence of otherwise-invisible low-mass planets and measure the build-up and destruction of planetesimals. To accomplish the science mission of GPI will require a dedicated instrument capable of achieving contrast of 10{sup -7} or more. This is vastly better than that delivered by existing astronomical AO systems. Currently achievable contrast, about 10{sup -5} at separations of 1 arc second or larger, is

  12. Habitable Zones Around Low-Mass Stars

    NASA Astrophysics Data System (ADS)

    Kopparapu, Ravi Kumar; Kasting, J. F.; Ramirez, R.

    2011-09-01

    Classically, the circumstellar habitable zone (HZ) is defined as the region inside which a terrestrial mass planet, with adequate supplies of carbon, water, and internal heat, can sustain liquid water on its surface (Kasting et al. 1993). A conservative estimate for the width of the HZ in our Solar system is 0.93-1.48 AU, assuming that the inner edge is limited by water loss and the outer edge is determined by the maximum greenhouse limit for a dense CO2 atmosphere. These numbers are revisions of ones published by Kasting et al. (1993), based on new climate modeling results. Kasting et al. obtained HZ boundaries for stars with effective temperatures between 3700 K and 7200 K--limits that do not include main-sequence M-dwarfs. In this study we use an updated 1-D radiative-convective, cloud-free climate model to estimate the width of the HZ around these low mass stars. Significant improvements in our climate model include: (1) updated collision-induced absorption coefficients for CO2 (critical for dense CO2 atmospheres at the outer edge) and (2) a revised Rayleigh scattering coefficient for H2O (important for water loss at the inner edge). Assuming Earth-like planets with CO2/H2O/N2 atmospheres, the width of the HZ is 0.24-0.44 AU around an early M star (Teff = 3600 K) and 0.05-0.09 AU for a late M star (Teff = 2800 K). As our model does not include the radiative effects of clouds, the actual HZ boundaries may extend further in both directions than our conservative estimates. Nonetheless, current ground-based surveys (e.g., the MEARTH project) and future space-based characterization missions (e.g., JWST/TPF) may be able to use these HZ boundaries to help guide their efforts to find habitable planets around main-sequence stars. (We acknowledge funding from NASA Astrobiology Institute's Virtual Planetary Laboratory, supported by NASA under cooperative agreement NNH05ZDA001C.)

  13. No universal minimum-mass extrasolar nebula: evidence against in situ accretion of systems of hot super-Earths

    NASA Astrophysics Data System (ADS)

    Raymond, Sean N.; Cossou, Christophe

    2014-05-01

    It has been proposed that the observed systems of hot super-Earths formed in situ from high-mass discs. By fitting a disc profile to the entire population of Kepler planet candidates, Chiang & Laughlin constructed a `minimum-mass extrasolar nebula' with surface density profile Σ ∝ r-1.6. Here, we use multiple-planet systems to show that it is inconsistent to assume a universal disc profile. Systems with 3-6 low-mass planets (or planet candidates) produce a diversity of minimum-mass discs with surface density profiles ranging from Σ ∝ r-3.2 to Σ ∝ r0.5 (5th-95th percentile). By simulating the transit detection of populations of synthetic planetary systems designed to match the properties of observed super-Earth systems, we show that a universal disc profile is statistically excluded at high confidence. Rather, the underlying distribution of minimum-mass discs is characterized by a broad range of surface density slopes. Models of gaseous discs can only explain a narrow range of slopes (roughly between r0 and r-1.5). Yet accretion of terrestrial planets in a gas-free environment preserves the initial radial distribution of building blocks. The known systems of hot super-Earths must therefore not represent the structure of their parent gas discs and cannot have predominantly formed in situ. We instead interpret the diversity of disc slopes as the imprint of a process that re-arranged the solids relative to the gas in the inner parts of protoplanetary discs. A plausible mechanism is inward type 1 migration of Mars- to Earth-mass planetary embryos, perhaps followed by a final assembly phase. L6

  14. Direct measurements of the fundamental properties of low-mass stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Dupuy, Trent J.

    2010-10-01

    [approximate]2 at a given mass, which means that model-based substellar mass determinations (e.g., for directly imaged extrasolar planets and the low-mass initial mass function) may be systematically overestimating the masses. (3) We have employed our large sample of binary orbits to carry out a novel test of the earliest evolutionary stages, by using the distribution of orbital eccentricities to distinguish between competing models of brown dwarf formation.

  15. Extrasolar comets : dynamics and composition

    NASA Astrophysics Data System (ADS)

    Lecavelier des Etangs, Alain; Wilson, Paul Anthony; Kiefer, Flavien

    2015-12-01

    Extrasolar comets, or exocomets, are detected using transit spectroscopy in young planetary systems.Spectroscopic observations of β Pictoris revealed a high rate of transits, allowing statistical analysis of exocomets populations. Using more than 1,000 archival spectra, we obtained a sample of several hundreds of signatures of exocomets transiting the disk of the parent star. Statistical analysis of the observed properties of these exocomets allowed the identification of two populations with different physical and dynamical properties. One family consists of exocomets producing shallow absorption lines at high radial velocities (>40 km/s), which can be attributed to old exhausted comets trapped in a mean motion resonance with a massive planet, possibly β Pic b. The second family consists of exocomets which produce deep absorption lines at low radial velocities (˜ 15 km/s), which could be related to the recent fragmentation of one or a few parent bodies.Most recently, our last HST/COS observations of β Pic yielded the first detection of exocomets in the far-UV. Several new species were detected for the first time in exocomets, including HI, CII, NI, OI and all the ionization states of Si. Measuring the abundance of the key species such as Hydrogen, Carbon, Nitrogen and Oxygen in evaporating exocomets allows us to trace the condensation and evaporation processes present in the late stages of planetary formation. Moreover, the measured radial velocities of these exocomets are consistent with the two dynamical populations previously identified. Most importantly, correlations between the dynamical properties and abundances seems to show up. In short, these two families of exocomets have different dynamical properties, and their origin could be determined by studying their chemical composition. I will present the latest results on that subject, and provide an overview of other systems for which signatures of exocomets have been observed.

  16. Tidally-induced thermal runaway on extrasolar Earth: Impact on habitability

    NASA Astrophysics Data System (ADS)

    Behounkova, M.; Tobie, G.; Choblet, G.; Cadek, O.

    2010-12-01

    Low mass extrasolar bodies start to be discovered owing to the increased precision of detection surveys. As the detection probability decreases with the star-body distance, these planets (and the numerous candidates already announced for the coming years) are likely to orbit their parent stars in a close distance. These short-period planets undergo a strong tidal forcing and their orbits are tidally locked. The associated heat production may influence the internal thermal evolution of these bodies: it has even been suggested that the habitable zone could be influenced by tidal heating (Barnes et al. 2008; Henning et al. 2009). In this study, we further investigate the effect of tidal heating on thermal evolution of tidally locked Earth-like planets. Owing to the strong temperature dependence of the mechanical properties of both the long-term evolution and the tidal deformations, the two processes are coupled. Nevertheless, the tidal deformation has no direct effect on the convective flow and only the dissipative part is included as a heat source for mantle dynamics since the time scales of the two processes strongly differs. For significant tidal dissipation rates, the strong positive feedback leads, in some cases, to thermal runaways. We focus here on the susceptibility of Earth-like planets to tidal dissipation for fixed orbital parameters (eccentricity, orbital period and the spin-orbit resonance type) and on the associated timescales for runaway (if any). In order to describe this behavior and the three dimensional nature of both the tidal forcing and the temperature anomalies, a fully three-dimensional approach solving the two processes simultaneously is employed (Běhounková et al., JGR, in press). We consider an extrasolar planet having the internal properties similar to the Earth. Two modes for heat transfer are modeled through the choice of convective parameters (Rayleigh number and temperature dependence of viscosity, amount of radiogenic heating): a

  17. Carbon to oxygen ratios in extrasolar planetesimals

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-04-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O <0.8 by number in all 16 systems. Our results place an upper limit on the occurrence of carbon-rich systems at <17 percent with a 2 σ confidence level. The range of C/O of the planetesimals is consistent with that found in the Solar System, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log ( < C/O > ) = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  18. Carbon to oxygen ratios in extrasolar planetesimals

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-07-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O < 0.8 by number in all 16 systems. Our results place an upper limit on the occurrence of carbon-rich systems at <17 per cent with a 2σ confidence level. The range of C/O of the planetesimals is consistent with that found in the Solar system, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log (< C/O >) = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  19. Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.

    2008-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime ( 5 year goal) and will revisit planets at least three times at intervals of 9 months. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology readiness the NASA Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed,

  20. Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass

    NASA Astrophysics Data System (ADS)

    Crepp, Justin R.; Johnson, John Asher

    2011-06-01

    We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, β Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple

  1. ESTIMATES OF THE PLANET YIELD FROM GROUND-BASED HIGH-CONTRAST IMAGING OBSERVATIONS AS A FUNCTION OF STELLAR MASS

    SciTech Connect

    Crepp, Justin R.; Johnson, John Asher

    2011-06-01

    We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, {beta} Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether

  2. Hazards to Planet Formation

    NASA Astrophysics Data System (ADS)