Science.gov

Sample records for sub-neptune mass planet

  1. Evolutionary Analysis of Gaseous Sub-Neptune-mass Planets with MESA

    NASA Astrophysics Data System (ADS)

    Chen, Howard; Rogers, Leslie A.

    2016-11-01

    Sub-Neptune-sized exoplanets represent the most common types of planets in the Milky Way, yet many of their properties are unknown. Here, we present a prescription to adapt the capabilities of the stellar evolution toolkit Modules for Experiments in Stellar Astrophysics to model sub-Neptune-mass planets with H/He envelopes. With the addition of routines treating the planet core luminosity, heavy-element enrichment, atmospheric boundary condition, and mass-loss due to hydrodynamic winds, the evolutionary pathways of planets with diverse starting conditions are more accurately constrained. Using these dynamical models, we construct mass-composition relationships of planets from 1-400 M ⊕ and investigate how mass-loss impacts their composition and evolution history. We demonstrate that planet radii are typically insensitive to the evolution pathway that brought the planet to its instantaneous mass, composition and age, with variations from hysteresis ≲ 2 % . We find that planet envelope mass-loss timescales, {τ }{env}, vary non-monotonically with H/He envelope mass fractions (at fixed planet mass). In our simulations of young (100 Myr) low-mass ({M}{{p}}≲ 10 {M}\\oplus ) planets with rocky cores, {τ }{env} is maximized at {M}{env}/{M}{{p}}=1 % to 3%. The resulting convergent mass-loss evolution could potentially imprint itself on the close-in planet population as a preferred H/He mass fraction of ˜ 1 % . Looking ahead, we anticipate that this numerical code will see widespread applications complementing both 3D models and observational exoplanet surveys.

  2. Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Rogers, Leslie A.; Ford, Eric B.

    2016-07-01

    The Kepler Mission has discovered thousands of planets with radii <4 {R}\\oplus , paving the way for the first statistical studies of the dynamics, formation, and evolution of these sub-Neptunes and super-Earths. Planetary masses are an important physical property for these studies, and yet the vast majority of Kepler planet candidates do not have theirs measured. A key concern is therefore how to map the measured radii to mass estimates in this Earth-to-Neptune size range where there are no Solar System analogs. Previous works have derived deterministic, one-to-one relationships between radius and mass. However, if these planets span a range of compositions as expected, then an intrinsic scatter about this relationship must exist in the population. Here we present the first probabilistic mass-radius relationship (M-R relation) evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters. We analyze how the results depend on the radius range of the sample, and on how the masses were measured. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that M/{M}\\oplus =2.7{(R/{R}\\oplus )}1.3, a scatter in mass of 1.9{M}\\oplus , and a mass constraint to physically plausible densities, is the “best-fit” probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes (R pl < 4 {R}\\oplus ). More broadly, this work provides a framework for further analyses of the M-R relation and its probable dependencies on period and stellar properties.

  3. Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Rogers, Leslie Anne; Ford, Eric B.

    2015-08-01

    The Kepler Mission has discovered thousands of super-Earths, paving the way for the first statistical studies of the dynamics, formation, and evolution of these planets. Planetary masses are an important physical property that these studies consider, and yet the vast majority of Kepler planet candidates do not have theirs measured. A key concern for these studies is therefore how to map the measured radii to mass estimates, in this regime of planetary sizes where there are no Solar System analogs. Previous works have derived deterministic, one-to-one relationships between radius and mass. However, if these planets span a range of compositions as expected, then an intrinsic scatter about this relationship must exist in the population. Here we present the first probabilistic mass-radius relationship (M-R relation) evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters given the data. We analyze how the details depend on the radius range of the sample, and on the method used to provide the mass measurements. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that M/M_Earth = 2.7 (R/R_Earth)^1.2 and a scatter in mass of 1.7 M_Earth is the "best-fit" probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes.

  4. Discovery and Mass Measurements of a Cold, Sub-Neptune Mass Planet and Its Host Star

    NASA Technical Reports Server (NTRS)

    Barry, Richard K., Jr.

    2011-01-01

    The gravitational microlensing exoplanet detection method is uniquely sensitive to cold, low-mass planets which orbit beyond the snow-line, where the most massive planets are thought to form. The early statistical results from microlensing indicate that Neptune-Saturn mass planets located beyond the snow-line are substantially more common than their counterparts in closer orbits that have found by the Doppler radial velocity method. We present the discovery of the planet MOA-2009-BLG-266Lb, which demonstrates that the gravitational microlensing method also has the capability to measure the masses of cold, low-mass planets. The mass measurements of the host star and the planet are made possible by the detection of the microlensing parallax signal due to the orbital motion or the Earth as well as observations from the EPOXI spacecraft in a Heliocentric orbit. The microlensing light curve indicates a planetary host star mass of M(sun) = 0.54 + / - 0.05M(sun) located at a distance of DL= 2.94 _ 0.21 kpc, orbited by a planet of mass mp= 9.8 +/-1.1M(Earth) with a semi-major axis of a = 3.1(+1.9-0.4)MAU.

  5. A Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets: Implications for Missions Post-Kepler

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Rogers, Leslie; Ford, Eric B.; Laughlin, Gregory P.

    2016-01-01

    The Kepler Mission has discovered thousands of planets with radii between 1 and 4 R_Earth, paving the way for the first statistical studies of the dynamics, formation, and evolution of planets in a size range where there are no Solar System analogs. Masses are an important physical property for these theoretical studies, and yet the vast majority of Kepler planet candidates do not have theirs measured. Therefore, a key practical concern is how to most accurately map a measured sub-Neptune radius to a mass estimate given the existing observations. This issue is also highly relevant to devising the most efficient follow-up programs of future transiting exoplanet detection missions such as TESS. Here we present a probabilistic mass-radius relationship (M-R relation) evaluated within a hierarchical Bayesian framework, which both accounts for the anticipated intrinsic dispersion in these planets' compositions and quantifies the uncertainties on the M-R relation parameters. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that M/M_Earth = 2.7 (R/R_Earth)^1.3 and a scatter in mass of 1.9 M_Earth is the "best-fit" probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes (R_pl < 4 R_Earth; Wolfgang, Rogers, & Ford, in review). The probabilistic nature of this M-R relation has several advantages: not only does its use automatically account for a significant source of uncertainty in the comparison between planet formation theory and observation, but it can predict the yield of future transit missions' follow-up programs under the observed range of planet compositions at a given radius. We demonstrate the latter with TESS as a case study, building on Sullivan et al. 2015 to provide the RV semi-amplitude distribution predicted by this more general M-R relation and a more detailed treatment of the underlying planet population as derived from Kepler. The uncertainties in the

  6. A Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets: Implications for Missions Post-Kepler

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Rogers, Leslie A.; Ford, Eric B.; Laughlin, Gregory

    2015-12-01

    The Kepler Mission has discovered thousands of planets with radii between 1 and 4 R_Earth, paving the way for the first statistical studies of the dynamics, formation, and evolution of planets in a size range where there are no Solar System analogs. Masses are an important physical property for these theoretical studies, and yet the vast majority of Kepler planet candidates do not have theirs measured. Therefore, a key practical concern is how to most accurately map a measured sub-Neptune radius to a mass estimate given the existing observations. This issue is also highly relevant to devising the most efficient follow-up programs of future transiting exoplanet detection missions such as TESS. Here we present a probabilistic mass-radius relationship (M-R relation) evaluated within a hierarchical Bayesian framework, which both accounts for the anticipated intrinsic dispersion in these planets' compositions and quantifies the uncertainties on the M-R relation parameters. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that M/M_Earth = 2.7 (R/R_Earth)^1.3 and a scatter in mass of 1.9 M_Earth is the "best-fit" probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes (R_pl < 4 R_Earth; Wolfgang, Rogers, & Ford, in review). The probabilistic nature of this M-R relation has several advantages: not only does its use automatically account for a significant source of uncertainty in the comparison between planet formation theory and observation, but it can predict the yield of future transit missions' follow-up programs under the observed range of planet compositions at a given radius. We demonstrate the latter with TESS as a case study, building on Sullivan et al. 2015 to provide the RV semi-amplitude distribution predicted by this more general M-R relation and a more detailed treatment of the underlying planet population as derived from Kepler. The uncertainties in the

  7. Discovery of the distant cool sub-Neptune mass planet OGLE 2005-BLG-390Lb by microlensing

    SciTech Connect

    Beaulieu, J P; Bennett, D P; Fouque, P; Williams, A; Dominik, M; Jorgensen, U G; Kubas, D; Cassan, A; Coutures, C; Greenhill, J; Hill, K; Menzies, J; Sackett, P D; Albrow, M; Brillant, S; Caldwell, J R; Calitz, J J; Cook, K H; Corrales, E; Desort, M; Dieters, S; Dominis, D; Donatowicz, J; Hoffman, M; Kane, S; Marquette, J B; Martin, R; Meintjes, P; Pollard, K; Sahu, K; Vinter, C; Wambsganss, J; Woller, K; Horne, K; Steele, I; Bramich, D M; Burgdorf, M; Snodgrass, C; Bode, M; Udalski, A; Szymanski, M K; Kubiak, M; Wieckowski, T; Pietrzynski, G; Soszynski, I; Szewczyk, O; Wyrzykowski, L; Paczynski, B; Abe, F; Bond, I A; Britton, T R; Gilmore, A C; Hearnshaw, J B; Itow, Y; Kamiya, K; Kilmartin, P M; Korpela, A V; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okada, C; Ohnishi, K; Rattenbury, N J; Sako, T; Sato, S; Sasaki, M; Sekiguchi, T; Sullivan, D J; Tristram, P J; Yock, P M; Yoskioka, T

    2005-11-07

    The favoured theoretical explanation for planetary systems formation is the core-accretion model in which solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars, the most common stars of our Galaxy, this model favours the formation of Earth- to Neptune-mass planets in a few million years with orbital sizes of 1 to 10 AU, which is consistent with the small number of detections of giant planets with M-dwarf host stars. More than 170 extrasolar planets have been discovered so far with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not previously been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5{sub -2.7}{sup +5.5} Earthmass planetary companion at a separation of 2.6{sub -0.6}{sup +1.5}AU from a 0.22{sub -0.11}{sup +0.21} M{sub e} M-dwarf star, which is the lens star for gravitational microlensing event OGLE 2005-BLG-390. This is the lowest mass ever reported for an extrasolar planet orbiting a main sequence star, although the error bars overlap those for the mass of GJ876d. Our detection suggests that such cool, sub-Neptune mass planets may be common than gas giant planets, as predicted by the core accretion theory.

  8. A resonant chain of four transiting, sub-Neptune planets.

    PubMed

    Mills, Sean M; Fabrycky, Daniel C; Migaszewski, Cezary; Ford, Eric B; Petigura, Erik; Isaacson, Howard

    2016-05-26

    Surveys have revealed many multi-planet systems containing super-Earths and Neptunes in orbits of a few days to a few months. There is debate whether in situ assembly or inward migration is the dominant mechanism of the formation of such planetary systems. Simulations suggest that migration creates tightly packed systems with planets whose orbital periods may be expressed as ratios of small integers (resonances), often in a many-planet series (chain). In the hundreds of multi-planet systems of sub-Neptunes, more planet pairs are observed near resonances than would generally be expected, but no individual system has hitherto been identified that must have been formed by migration. Proximity to resonance enables the detection of planets perturbing each other. Here we report transit timing variations of the four planets in the Kepler-223 system, model these variations as resonant-angle librations, and compute the long-term stability of the resonant chain. The architecture of Kepler-223 is too finely tuned to have been formed by scattering, and our numerical simulations demonstrate that its properties are natural outcomes of the migration hypothesis. Similar systems could be destabilized by any of several mechanisms, contributing to the observed orbital-period distribution, where many planets are not in resonances. Planetesimal interactions in particular are thought to be responsible for establishing the current orbits of the four giant planets in the Solar System by disrupting a theoretical initial resonant chain similar to that observed in Kepler-223.

  9. Understanding the mass-radius relation for sub-Neptunes: radius as a proxy for composition

    SciTech Connect

    Lopez, Eric D.; Fortney, Jonathan J.

    2014-09-01

    Transiting planet surveys like Kepler have provided a wealth of information on the distribution of planetary radii, particularly for the new populations of super-Earth- and sub-Neptune-sized planets. In order to aid in the physical interpretation of these radii, we compute model radii for low-mass rocky planets with hydrogen-helium envelopes. We provide model radii for planets 1-20 M {sub ⊕}, with envelope fractions 0.01%-20%, levels of irradiation 0.1-1000 times Earth's, and ages from 100 Myr to 10 Gyr. In addition we provide simple analytic fits that summarize how radius depends on each of these parameters. Most importantly, we show that at fixed H/He envelope fraction, radii show little dependence on mass for planets with more than ∼1% of their mass in their envelope. Consequently, planetary radius is to a first order a proxy for planetary composition, i.e., H/He envelope fraction, for Neptune- and sub-Neptune-sized planets. We recast the observed mass-radius relationship as a mass-composition relationship and discuss it in light of traditional core accretion theory. We discuss the transition from rocky super-Earths to sub-Neptune planets with large volatile envelopes. We suggest ∼1.75 R {sub ⊕} as a physically motivated dividing line between these two populations of planets. Finally, we discuss these results in light of the observed radius occurrence distribution found by Kepler.

  10. Kepler-223: A Resonant Chain of Four Sub-Neptune Planets

    NASA Astrophysics Data System (ADS)

    Mills, Sean M.; Clark Fabrycky, Daniel; Migaszewski, Cezary; Ford, Eric B.; Petigura, Erik; Isaacson, Howard T.

    2015-12-01

    The Kepler mission has revealed an abundance of pairs of planets in the same system which often lie near, but not exactly on, resonance. Understanding how and when they entered a resonance and were removed from it has implications for their birthplaces and planetary structure. Here we characterize Kepler-223 (KOI-730), an outstanding example of a system of small planets in resonance. We perform TTV, photodynamic, stability, and migration analyses to determine the system's most likely current parameters and resonant state. Its four sub-Neptune planets form a chain linked by 4:3, 3:2, and 2:1 resonances that cause measurable dynamical effects and imply a disk-migration origin. Tidal dissipation in the planets or wide-scale instability may eventually transform resonant chains of planets like Kepler-223 into the more common type of architecture.

  11. Measuring the Masses and Radii of Sub-Neptunes with Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Lissauer, J. J.; Rowe, J. F.; Fabrycky, D.

    2013-10-01

    The bounty of sub-Neptunes discovered by Kepler enables us to study a regime in planetary size and mass that is absent from the Solar System. This regime includes a transition from rocky planets to those with substantial amounts of volatiles-- in either ice mantles or deep atmospheres. Characterizing these worlds by their bulk densities can probe this transition, and this requires mass and radius determinations. Outside our solar system, there is a small sample of planets with known masses and radii, mostly hot jupiters whose radii are known from transit depths, and whose masses are determined from radial velocity spectroscopy (RV). In the absence of mass determinations via RV observations, transit timing variations (TTVs) offer a chance to probe perturbations between planets that pass close to one another or are near resonance, and hence dynamical fits to observed transit times can measure planetary masses and orbital parameters. Such modelling can probe planetary masses at longer orbital periods than RV targets, although not without some challenges. For example, in modeling pairwise planetary perturbations, a degeneracy between eccentricity and mass exists that limits the accuracy of mass determinations. Nevertheless, in several compact multiplanet systems, fitting complex TTV signals can break the degeneracy, permitting useful mass determinations. The precision in measuring the radius of a transiting planet rests on the uncertainty in the stellar radius, which is typically ~10% for targets with spectral follow-up. With dynamical fits, however, solutions for the orbital parameters including the eccentricity vectors can, alongside the transit lightcurves, tightly constrain the stellar density and radius. Revisiting the six-planet system of Kepler-11, our dynamical fits to TTVs, alongside spectroscopic data on the host star, reduced the stellar and hence planetary radius uncertainties to just 2%, permitting useful planetary density determinations. In the case of

  12. Mass-radius relations and core-envelope decompositions of super-Earths and sub-Neptunes

    SciTech Connect

    Howe, Alex R.; Burrows, Adam; Verne, Wesley E-mail: burrows@astro.princeton.edu

    2014-06-01

    Many exoplanets have been discovered with radii of 1-4 R {sub ⊕}, between that of Earth and Neptune. A number of these are known to have densities consistent with solid compositions, while others are 'sub-Neptunes' likely to have significant H{sub 2}-He envelopes. Future surveys will no doubt significantly expand these populations. In order to understand how the measured masses and radii of such planets can inform their structures and compositions, we construct models both for solid layered planets and for planets with solid cores and gaseous envelopes, exploring a range of core masses, H{sub 2}-He envelope masses, and associated envelope entropies. For planets in the super-Earth/sub-Neptune regime for which both radius and mass are measured, we estimate how each is partitioned into a solid core and gaseous envelope, associating a specific core mass and envelope mass with a given exoplanet. We perform this decomposition for both ''Earth-like'' rock-iron cores and pure ice cores, and find that the necessary gaseous envelope masses for this important sub-class of exoplanets must range very widely from zero to many Earth masses, even for a given core mass. This result bears importantly on exoplanet formation and envelope evaporation processes.

  13. K2-66b and K2-106b: Two Extremely Hot Sub-Neptune-size Planets with High Densities

    NASA Astrophysics Data System (ADS)

    Sinukoff, Evan; Howard, Andrew W.; Petigura, Erik A.; Fulton, Benjamin J.; Crossfield, Ian J. M.; Isaacson, Howard; Gonzales, Erica; Crepp, Justin R.; Brewer, John M.; Hirsch, Lea; Weiss, Lauren M.; Ciardi, David R.; Schlieder, Joshua E.; Benneke, Bjoern; Christiansen, Jessie L.; Dressing, Courtney D.; Hansen, Brad M. S.; Knutson, Heather A.; Kosiarek, Molly; Livingston, John H.; Greene, Thomas P.; Rogers, Leslie A.; Lépine, Sébastien

    2017-06-01

    We report precise mass and density measurements of two extremely hot sub-Neptune-size planets from the K2 mission using radial velocities, K2 photometry, and adaptive optics imaging. K2-66 harbors a close-in sub-Neptune-sized ({2.49}-0.24+0.34 {R}\\oplus ) planet (K2-66b) with a mass of 21.3+/- 3.6 {M}\\oplus . Because the star is evolving up the subgiant branch, K2-66b receives a high level of irradiation, roughly twice the main-sequence value. K2-66b may reside within the so-called “photoevaporation desert,” a domain of planet size and incident flux that is almost completely devoid of planets. Its mass and radius imply that K2-66b has, at most, a meager envelope fraction (<5%) and perhaps no envelope at all, making it one of the largest planets without a significant envelope. K2-106 hosts an ultra-short-period planet (P = 13.7 hr) that is one of the hottest sub-Neptune-size planets discovered to date. Its radius ({1.82}-0.14+0.20 {R}\\oplus ) and mass (9.0+/- 1.6 {M}\\oplus ) are consistent with a rocky composition, as are all other small ultra-short-period planets with well-measured masses. K2-106 also hosts a larger, longer-period planet ({R}{{p}} = {2.77}-0.23+0.37 {R}\\oplus , P = 13.3 days) with a mass less than 24.4 {M}\\oplus at 99.7% confidence. K2-66b and K2-106b probe planetary physics in extreme radiation environments. Their high densities reflect the challenge of retaining a substantial gas envelope in such extreme environments.

  14. Formation of isothermal disks around protoplanets. I. Introductory three-dimensional global simulations for sub-Neptune-mass protoplanets

    SciTech Connect

    Wang, Hsiang-Hsu; Shang, Hsien; Gu, Pin-Gao; Bu, Defu

    2014-07-20

    The regular satellites found around Neptune (≈17 M{sub ⊕}) and Uranus (≈14.5 M{sub ⊕}) suggest that past gaseous circumplanetary disks may have co-existed with solids around sub-Neptune-mass protoplanets (<17 M{sub ⊕}). These disks have been shown to be cool, optically thin, and quiescent, with low surface densities and low viscosities. Numerical studies of the formation are difficult and technically challenging. As an introductory attempt, three-dimensional global simulations are performed to explore the formation of circumplanetary disks around sub-Neptune-mass protoplanets embedded within an isothermal protoplanetary disk at the inviscid limit of the fluid in the absence of self-gravity. Under such conditions, a sub-Neptune-mass protoplanet can reasonably have a rotationally supported circumplanetary disk. The size of the circumplanetary disk is found to be roughly one-tenth of the corresponding Hill radius, which is consistent with the orbital radii of irregular satellites found for Uranus. The protoplanetary gas accretes onto the circumplanetary disk vertically from high altitude and returns to the protoplanetary disk again near the midplane. This implies an open system in which the circumplanetary disk constantly exchanges angular momentum and material with its surrounding prenatal protoplanetary gas.

  15. How Thermal Evolution and Mass-loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond

    NASA Astrophysics Data System (ADS)

    Lopez, Eric D.; Fortney, Jonathan J.; Miller, Neil

    2012-12-01

    We use models of thermal evolution and extreme ultraviolet (XUV) driven mass loss to explore the composition and history of low-mass, low-density transiting planets. We investigate the Kepler-11 system in detail and provide estimates of both the current and past planetary compositions. We find that an H/He envelope on Kepler-11b is highly vulnerable to mass loss. By comparing to formation models, we show that in situ formation of the system is extremely difficult. Instead we propose that it is a water-rich system of sub-Neptunes that migrated from beyond the snow line. For the broader population of observed planets, we show that there is a threshold in bulk planet density and incident flux above which no low-mass transiting planets have been observed. We suggest that this threshold is due to the instability of H/He envelopes to XUV-driven mass loss. Importantly, we find that this mass-loss threshold is well reproduced by our thermal evolution/contraction models that incorporate a standard mass-loss prescription. Treating the planets' contraction history is essential because the planets have significantly larger radii during the early era of high XUV fluxes. Over time low-mass planets with H/He envelopes can be transformed into water-dominated worlds with steam envelopes or rocky super-Earths. Finally, we use this threshold to provide likely minimum masses and radial-velocity amplitudes for the general population of Kepler candidates. Likewise, we use this threshold to provide constraints on the maximum radii of low-mass planets found by radial-velocity surveys.

  16. HOW THERMAL EVOLUTION AND MASS-LOSS SCULPT POPULATIONS OF SUPER-EARTHS AND SUB-NEPTUNES: APPLICATION TO THE KEPLER-11 SYSTEM AND BEYOND

    SciTech Connect

    Lopez, Eric D.; Miller, Neil; Fortney, Jonathan J.

    2012-12-10

    We use models of thermal evolution and extreme ultraviolet (XUV) driven mass loss to explore the composition and history of low-mass, low-density transiting planets. We investigate the Kepler-11 system in detail and provide estimates of both the current and past planetary compositions. We find that an H/He envelope on Kepler-11b is highly vulnerable to mass loss. By comparing to formation models, we show that in situ formation of the system is extremely difficult. Instead we propose that it is a water-rich system of sub-Neptunes that migrated from beyond the snow line. For the broader population of observed planets, we show that there is a threshold in bulk planet density and incident flux above which no low-mass transiting planets have been observed. We suggest that this threshold is due to the instability of H/He envelopes to XUV-driven mass loss. Importantly, we find that this mass-loss threshold is well reproduced by our thermal evolution/contraction models that incorporate a standard mass-loss prescription. Treating the planets' contraction history is essential because the planets have significantly larger radii during the early era of high XUV fluxes. Over time low-mass planets with H/He envelopes can be transformed into water-dominated worlds with steam envelopes or rocky super-Earths. Finally, we use this threshold to provide likely minimum masses and radial-velocity amplitudes for the general population of Kepler candidates. Likewise, we use this threshold to provide constraints on the maximum radii of low-mass planets found by radial-velocity surveys.

  17. How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes

    NASA Astrophysics Data System (ADS)

    Lopez, Eric; Fortney, J. J.

    2013-01-01

    We use models of planetary thermal evolution and XUV-driven mass loss to explore the composition and history of low-mass low-density transiting planets, such as those found by Kepler. We examine how a planet's mass loss history varies with its structural and orbital properties and provide simple analytic estimates of the behavior. We investigate the Kepler-36 system in detail and provide estimates of both the current and past planetary compositions. We show the differences in mass loss history provide a natural explanation for the large density contrast between Kepler-36b and Kepler-36c. For the broader population of observed planets, we find that there is a threshold in bulk planet density, mass, and incident flux above which no low-mass transiting planets have been observed. We suggest that this threshold is due to the instability of H/He atmospheres to XUV-driven mass loss. Importantly, we find that this flux-density threshold is well reproduced by our thermal evolution/contraction models. Over time low mass planets with H/He envelopes can be transformed into water-dominated worlds with steam atmospheres or rocky super-Earths.

  18. Measuring the masses, radii and orbital eccentricities of sub-Neptunes with transit timing variations.

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Lissauer, Jack J.; Rowe, Jason; Fabrycky, Daniel C.

    2014-05-01

    Outside our solar system, there is a small sample of planets with known masses and radii, mostly hot jupiters whose radii are known from transit depths, and whose masses are determined from radial velocity spectroscopy (RV). In the absence of mass determinations via RV observations, transit timing variations (TTVs) offer a chance to probe perturbations between planets that pass close to one another or are near resonance, and hence dynamical fits to observed transit times can measure planetary masses and orbital parameters. Such modeling can probe planetary masses at longer orbital periods than RV targets, although not without some challenges. For example, in modeling pairwise planetary perturbations near first order mean motion resonances, a degeneracy between eccentricity and mass exists that limits the accuracy of mass determinations. Nevertheless, in several compact multiplanet systems, fitting complex TTV signals can break the degeneracy, permitting useful mass constraints, and precise measures of small but non-zero eccentricity.The precision in measuring the radius of a transiting planet rests on the uncertainty in the stellar radius, which is typically ~10% for targets with spectral follow-up. With dynamical fits, however, solutions for the orbital parameters including the eccentricity vectors can, alongside the transit light curves, tightly constrain the stellar density and radius. Alongside spectroscopic data, our dynamical fits to TTVs reduced the stellar and hence planetary radius uncertainties at Kepler-11 and Kepler-79 to just 2%, permitting useful planetary density determinations. In the case of Kepler-79, planetary bulk densities are remarkably low given the planetary masses. Indeed, several multiplanet systems characterized by TTV show much lower planetary densities than typical RV determinations in the same mass range. While this reflects the detection biases of both techniques, it also represents a growing sample of characterized systems of

  19. Identifying the `true' radius of the hot sub-Neptune CoRoT-24b by mass-loss modelling

    NASA Astrophysics Data System (ADS)

    Lammer, H.; Erkaev, N. V.; Fossati, L.; Juvan, I.; Odert, P.; Cubillos, P. E.; Guenther, E.; Kislyakova, K. G.; Johnstone, C. P.; Lüftinger, T.; Güdel, M.

    2016-09-01

    For the hot exoplanets CoRoT-24b and CoRoT-24c, observations have provided transit radii RT of 3.7 ± 0.4R⊕ and 4.9 ± 0.5R⊕, and masses of ≤5.7M⊕ and 28 ± 11M⊕, respectively. We study their upper atmosphere structure and escape applying an hydrodynamic model. Assuming RT ≈ RPL, where RPL is the planetary radius at the pressure of 100 mbar, we obtained for CoRoT-24b unrealistically high thermally driven hydrodynamic escape rates. This is due to the planet's high temperature and low gravity, independent of the stellar EUV flux. Such high escape rates could last only for <100 Myr, while RPL shrinks till the escape rate becomes less than or equal to the maximum possible EUV-driven escape rate. For CoRoT-24b, RPL must be therefore located at ≈1.9-2.2R⊕ and high altitude hazes/clouds possibly extinct the light at RT. Our analysis constraints also the planet's mass to be 5-5.7M⊕. For CoRoT-24c, RPL and RT lie too close together to be distinguished in the same way. Similar differences between RPL and RT may be present also for other hot, low-density sub-Neptunes.

  20. From Sub-Neptunes to Earth-like Exoplanets: Modeling Optically Thick and Thin Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Chen, Howard; Rogers, Leslie; Kasting, James

    2016-01-01

    Exoplanet surveys have revealed a wide diversity of planet properties in the Milky Way. Here, we present the results from two projects modeling planet atmospheres; one considering the hydrogen/helium envelopes of sub-Neptune-mass planets, and the other, the climate of Earth-like planets.First, we modify the state-of-the-art stellar evolution code Modules for Experimental Astrophysics (MESA) to model the thermal evolution of gaseous Sub-Neptune sized planets. Including photo-evaporation, we find a resulting convergent evolution trend that could potentially imprint itself on the close-in planet population as a preferred H/He mass fraction of 0.5-3%.We also use an updated version of a radiative-convective climate model to calculate the upper atmospheric conditions of planets warmer than the present Earth. In our simulations, cold, dry stratospheres are predicted at lower surface temperatures. However, onset of moist greenhouse water-loss limit to habitability emerges when the surface temperature reaches above 350 K. This result places constraint on a more accurate calculation of the inner edge of the habitable zone around Sun-like stars.

  1. How Thermal Evolution and Photo-Evaporation Sculpt Kepler's Sub-Neptunes and Super-Earths

    NASA Astrophysics Data System (ADS)

    Lopez, Eric; Fortney, J. J.

    2013-10-01

    NASA's Kepler mission has discovered a large new population of super-Earth and sub-Neptune sized planets. Although we have no analogous planet in our own solar system, such planets are incredibly common. Understanding the nature and formation of systems of these planets is one of the key challenges for theories of planet formation. We use models of thermal evolution and photo-evaporation to examine the structure, composition, and evolution of low-mass planets. Over time Neptune like planets with large H/He envelopes can be transformed into rocky super-Earths. We show that differences in mass loss history provide a natural explanation for many features of the Kepler multi-planet systems, such as large density contrast between Kepler-36b and Kepler-36c. For the broader population of Kepler planets, we find that there is a threshold in bulk planet density, mass, and incident flux above which no low-mass transiting planets have been observed. We suggest that this threshold is due to XUV-driven photo-evaporation and show that it is well reproduced by our evolution models.

  2. Combining Kepler and HARPS Exoplanet Occurrence Rates to Infer the Period-Mass-Radius Distribution of Super-Earths/Sub-Neptunes

    NASA Astrophysics Data System (ADS)

    Wolfgang, A.; Laughlin, G.

    2011-12-01

    The ongoing High Accuracy Radial velocity Planet Search (HARPS) has found that 30-50% of FGK stars in the solar neighborhood host planets with Mpl < MNep in orbits of P < 50 days. At first glance, this high overall occurrence rate seems at best to be marginally consistent with the planet frequency measured during Q0-Q2 of the Kepler Mission, whose 1235 detected planetary candidates imply that ˜ 15% of main sequence dwarfs harbor a short-period planet with Rpl < 4 R⊕ . A rigorous comparison between the two surveys is difficult, however, as they observe different stellar populations, measure different planetary physical properties, and are subject to radically different sampling plans. In this article, we report the results of a Monte Carlo study which seeks to partially overcome this apparent discrepancy by identifying plausible planetary population distributions which can jointly conform to the results of the two surveys. We find that a population concurrently consisting of (1) dense silicate-iron planets and (2) low-density volatile and gas-dominated worlds provides a natural fit to the current data. In this scenario, the fraction of dense planets decreases with increasing mass, from frocky = 90% at M = 1 M⊕ to frocky = 10% at M = MNep. Our best fit population has a total occurrence rate of 40% for 2 ≤ P ≤ 50 days and 1 ≤ M ≤ 17 M⊕ , and is characterized by simple power-law indices of the form N(M)dM ∝ Mα dM and N(P)dP ∝ Pβ dP with α = -1.0 and β = 0.0. Our model population therefore contains four free parameters and is readily testable with future observations. Furthermore, our model's insistence that at least two distinct types of planets must exist in the survey data indicates that multiple formation mechanisms are at work to produce the population of planets commonly referred to as ``super-Earths".

  3. BULK COMPOSITION OF GJ 1214b AND OTHER SUB-NEPTUNE EXOPLANETS

    SciTech Connect

    Valencia, Diana; Guillot, Tristan; Parmentier, Vivien; Freedman, Richard S.

    2013-09-20

    GJ 1214b stands out among the detected low-mass exoplanets, because it is, so far, the only one amenable to transmission spectroscopy. Up to date there is no consensus about the composition of its envelope although most studies suggest a high molecular weight atmosphere. In particular, it is unclear if hydrogen and helium are present or if the atmosphere is water dominated. Here, we present results on the composition of the envelope obtained by using an internal structure and evolutionary model to fit the mass and radius data. By examining all possible mixtures of water and H/He, with the corresponding opacities, we find that the bulk amount of H/He of GJ 1214b is at most 7% by mass. In general, we find the radius of warm sub-Neptunes to be most sensitive to the amount of H/He. We note that all (Kepler-11b,c,d,f, Kepler-18b, Kepler-20b, 55Cnc-e, Kepler-36c, and Kepler-68b) but two (Kepler-11e and Kepler-30b) of the discovered low-mass planets so far have less than 10% H/He. In fact, Kepler-11e and Kepler-30b have 10%-18% and 5%-15% bulk H/He. Conversely, little can be determined about the H{sub 2}O or rocky content of sub-Neptune planets. We find that although a 100% water composition fits the data for GJ 1214b, based on formation constraints the presence of heavier refractory material on this planet is expected, and hence, so is a component lighter than water required. The same is true for Kepler-11f. A robust determination by transmission spectroscopy of the composition of the upper atmosphere of GJ 1214b will help determine the extent of compositional segregation between the atmosphere and the envelope.

  4. Determining the Atmospheric Nature of Super-Earth and Sub-Neptune Exoplanets

    NASA Astrophysics Data System (ADS)

    Lothringer, Joshua; Crossfield, Ian; Benneke, Bjoern; Knutson, Heather; Dragomir, Diana; Fortney, Jonathan J.; Howard, Andrew; McCullough, Peter R.; Gilliland, Ronald L.; Kempton, Eliza; Morley, Caroline

    2016-01-01

    Proper characterization of the atmospheric composition of super-Earth and sub-Neptune planets will constrain the models that describe the formation and evolution of exoplanetary systems, yet the transition between Earth-mass and Neptune-mass exoplanets is still not well understood. Due to degeneracies between the bulk density and composition of planets in this range, even the basic make-up of many planets is unknown. Transit spectroscopy offers a method to characterize exoplanetary atmospheres and break this compositional degeneracy. We will present preliminary analysis and data reduction techniques for an ongoing large-scale Hubble Space Telescope survey of five planets between 1 and 22 Earth-masses. Using both optical and infrared primary transit spectra from STIS and WFC3, we will measure molecular signatures in the atmospheres of these small, cool planets, as well as any high-altitude clouds and hazes that may dampen such signatures. Results from this investigation will pave the way for future observations of small planets, especially in preparation for the James Webb Space Telescope (JWST) and the Transiting Exoplanet Survey Satellite (TESS).

  5. Kepler Planet Masses and Eccentricities from Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Hadden, Sam; Lithwick, Yoram

    2017-01-01

    The Kepler mission’s census of transiting exoplanets has shown that planets between one and four times the radius of Earth with short orbital periods are extremely common. Given their small sizes, the properties of these planets can be difficult or impossible to constrain via radial velocity observations. Mutual gravitational interactions in multi-planet systems induce variations in the arrival times of planets’ transits. These variations can used to probe planets’ masses and eccentricities, which in turn constrain their compositions and formation histories. I will discuss the results of our analysis of the transit timing variations (TTVs) of 145 Kepler planets from 55 multi-planet systems. Bulk densities inferred from TTVs imply that many of these planets are covered in gaseous envelopes ranging from a few percent to ~20% of their total mass. Eccentricities in these systems are small but in a many instances definitively non-zero. These results support theoretical predictions for super-Earth/sub-Neptune planets accreting their envelopes from a depleting proto-planetary disk.

  6. HELIUM ATMOSPHERES ON WARM NEPTUNE- AND SUB-NEPTUNE-SIZED EXOPLANETS AND APPLICATIONS TO GJ 436b

    SciTech Connect

    Hu, Renyu; Yung, Yuk L.; Seager, Sara

    2015-07-01

    Warm Neptune- and sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptune- and sub-Neptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydrogen, and therefore the escape is heavily affected by diffusive separation between hydrogen and helium. A helium atmosphere can thus be formed—from a primordial hydrogen–helium atmosphere—via atmospheric hydrodynamic escape from the planet. The helium atmosphere has very different abundances of major carbon and oxygen species from those of a hydrogen atmosphere, leading to distinctive transmission and thermal emission spectral features. In particular, the hypothesis of a helium-dominated atmosphere can explain the thermal emission spectrum of GJ 436b, a warm Neptune-sized exoplanet, while also being consistent with the transmission spectrum. This model atmosphere contains trace amounts of hydrogen, carbon, and oxygen, with the predominance of CO over CH{sub 4} as the main form of carbon. With our atmospheric evolution model, we find that if the mass of the initial atmosphere envelope is 10{sup −3} planetary mass, hydrodynamic escape can reduce the hydrogen abundance in the atmosphere by several orders of magnitude in ∼10 billion years. Observations of exoplanet transits may thus detect signatures of helium atmospheres and probe the evolutionary history of small exoplanets.

  7. Discovery and Validation of a High-Density sub-Neptune from the K2 Mission

    NASA Astrophysics Data System (ADS)

    Espinoza, Néstor; Brahm, Rafael; Jordán, Andrés; Jenkins, James S.; Rojas, Felipe; Jofré, Paula; Mädler, Thomas; Rabus, Markus; Chanamé, Julio; Pantoja, Blake; Soto, Maritza G.; Morzinski, Katie M.; Males, Jared R.; Ward-Duong, Kimberly; Close, Laird M.

    2016-10-01

    We report the discovery of K2-56b, a high-density sub-Neptune exoplanet, made using photometry from Campaign 4 of the two-wheeled Kepler (K2) mission, ground-based radial velocity (RV) follow-up from HARPS and high-resolution lucky and adaptive optics imaging obtained using AstraLux and MagAO, respectively. The host star is a bright (V = 11.04, K s = 9.37), slightly metal-poor ([Fe/H] = -0.15 ± 0.05 dex) solar analogue located at {152.1}-7.4+9.7 pc from Earth, for which we find a radius of {R}* ={0.928}-0.040+0.055{R}⊙ and a mass of {M}* ={0.961}-0.029+0.032{M}⊙ . A joint analysis of the K2 photometry and HARPS RVs reveal that the planet is in a ≈42 day orbit around its host star, has a radius of {2.23}-0.11+0.14{R}\\oplus , and a mass of {16.3}-6.1+6.0{M}\\oplus . Although the data at hand put the planet in the region of the mass-radius diagram where we could expect planets with a pure rock (i.e., magnesium silicate) composition using two-layer models (i.e., between rock/iron and rock/ice compositions), we discuss more realistic three-layer composition models which can explain the high density of the discovered exoplanet. The fact that the planet lies in the boundary between “possibly rocky” and “non-rocky” exoplanets makes it an interesting planet for future RV follow-up.

  8. MOA-2010-BLG-328Lb: A sub-Neptune orbiting very late M dwarf?

    SciTech Connect

    Furusawa, K.; Abe, F.; Itow, Y.; Masuda, K.; Matsubara, Y.; Udalski, A.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Ling, C. H.; Gould, A.; Jørgensen, U. G.; Snodgrass, C.; Prester, D. Dominis; Albrow, M. D.; Botzler, C. S.; Freeman, M.; Chote, P.; Harris, P.; Fukui, A. E-mail: liweih@astro.ucla.edu E-mail: rzellem@lpl.arizona.edu; Collaboration: MOA Collaboration; OGLE Collaboration; μFUN Collaboration; MiNDSTEp Consortium; RoboNet Collaboration; PLANET Collaboration; and others

    2013-12-20

    We analyze the planetary microlensing event MOA-2010-BLG-328. The best fit yields host and planetary masses of M {sub h} = 0.11 ± 0.01 M {sub ☉} and M {sub p} = 9.2 ± 2.2 M {sub ⊕}, corresponding to a very late M dwarf and sub-Neptune-mass planet, respectively. The system lies at D {sub L} = 0.81 ± 0.10 kpc with projected separation r = 0.92 ± 0.16 AU. Because of the host's a priori unlikely close distance, as well as the unusual nature of the system, we consider the possibility that the microlens parallax signal, which determines the host mass and distance, is actually due to xallarap (source orbital motion) that is being misinterpreted as parallax. We show a result that favors the parallax solution, even given its close host distance. We show that future high-resolution astrometric measurements could decisively resolve the remaining ambiguity of these solutions.

  9. Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing.

    PubMed

    Beaulieu, J-P; Bennett, D P; Fouqué, P; Williams, A; Dominik, M; Jørgensen, U G; Kubas, D; Cassan, A; Coutures, C; Greenhill, J; Hill, K; Menzies, J; Sackett, P D; Albrow, M; Brillant, S; Caldwell, J A R; Calitz, J J; Cook, K H; Corrales, E; Desort, M; Dieters, S; Dominis, D; Donatowicz, J; Hoffman, M; Kane, S; Marquette, J-B; Martin, R; Meintjes, P; Pollard, K; Sahu, K; Vinter, C; Wambsganss, J; Woller, K; Horne, K; Steele, I; Bramich, D M; Burgdorf, M; Snodgrass, C; Bode, M; Udalski, A; Szymański, M K; Kubiak, M; Wieckowski, T; Pietrzyński, G; Soszyński, I; Szewczyk, O; Wyrzykowski, L; Paczyński, B; Abe, F; Bond, I A; Britton, T R; Gilmore, A C; Hearnshaw, J B; Itow, Y; Kamiya, K; Kilmartin, P M; Korpela, A V; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okada, C; Ohnishi, K; Rattenbury, N J; Sako, T; Sato, S; Sasaki, M; Sekiguchi, T; Sullivan, D J; Tristram, P J; Yock, P C M; Yoshioka, T

    2006-01-26

    In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M(o)) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a 5.5(+5.5)(-2.7) M(o) planetary companion at a separation of 2.6+1.5-0.6 au from a 0.22+0.21-0.11 M(o) M-dwarf star, where M(o) refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.

  10. The Mass Function of Planets

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    2017-06-01

    The distribution of orbital period ratios of adjacent planets in extrasolar planetary systems discovered by the Kepler space telescope exhibits a peak near 1.5-2, a long tail of larger period ratios, and a steep drop-off in the number of systems with period ratios below 1.5. We find from these data that the dimensionless orbital separations have an approximately log-normal distribution. Using Hill’s criterion for the dynamical stability of two planets, we find that the upper bound on the most common planet-to-star mass ratio is 10-3.2m*, about two-thirds of the mass of Jupiter orbiting solar mass stars. Assuming that the mass ratio and the dynamical separation of adjacent planets are independent random variates, and adopting empirical distributions for these, we calculate the planet mass distribution function from the observed distribution of orbital period ratios. We find that the planet mass function is a rolling power law, steeper at higher mass, with an index of approximately -1.2 near jovian planet masses and a shallower index of approximately -0.6 near terrestrial planet masses.We are grateful for research funding from NSF (grant AST-1312498) and NASA (grant NNX14AG93G).

  11. 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 (mass) using a combination of analytic and numerical calculations, and I will show that all low-mass planets obey a kind of universal mass-radius relationship: an expansion whose first term is M approx. R(sup 3).

  12. 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 (mass) using a combination of analytic and numerical calculations, and I will show that all low-mass planets obey a kind of universal mass-radius relationship: an expansion whose first term is M approx. R(sup 3).

  13. A generalized Bayesian inference method for constraining the interiors of super Earths and sub-Neptunes

    NASA Astrophysics Data System (ADS)

    Dorn, Caroline; Venturini, Julia; Khan, Amir; Heng, Kevin; Alibert, Yann; Helled, Ravit; Rivoldini, Attilio; Benz, Willy

    2017-01-01

    Aims: We aim to present a generalized Bayesian inference method for constraining interiors of super Earths and sub-Neptunes. Our methodology succeeds in quantifying the degeneracy and correlation of structural parameters for high dimensional parameter spaces. Specifically, we identify what constraints can be placed on composition and thickness of core, mantle, ice, ocean, and atmospheric layers given observations of mass, radius, and bulk refractory abundance constraints (Fe, Mg, Si) from observations of the host star's photospheric composition. Methods: We employed a full probabilistic Bayesian inference analysis that formally accounts for observational and model uncertainties. Using a Markov chain Monte Carlo technique, we computed joint and marginal posterior probability distributions for all structural parameters of interest. We included state-of-the-art structural models based on self-consistent thermodynamics of core, mantle, high-pressure ice, and liquid water. Furthermore, we tested and compared two different atmospheric models that are tailored for modeling thick and thin atmospheres, respectively. Results: First, we validate our method against Neptune. Second, we apply it to synthetic exoplanets of fixed mass and determine the effect on interior structure and composition when (1) radius; (2) atmospheric model; (3) data uncertainties; (4) semi-major axes; (5) atmospheric composition (i.e., a priori assumption of enriched envelopes versus pure H/He envelopes); and (6) prior distributions are varied. Conclusions: Our main conclusions are: (1) given available data, the range of possible interior structures is large; quantification of the degeneracy of possible interiors is therefore indispensable for meaningful planet characterization. (2) Our method predicts models that agree with independent estimates of Neptune's interior. (3) Increasing the precision in mass and radius leads to much improved constraints on ice mass fraction, size of rocky interior, but

  14. Planet Masses from Disk Spirals

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-12-01

    Young, forming planets can generate immense spiral structures within their protoplanetary disks. A recent study has shown that observations of these spiral structures may allow astronomers to measure the mass of the planets that create them.Spirals From WavesSnapshots of the surface density of a protoplanetary disk in a 2D simulation, 3D simulation, and synthesized scattered-light image. Click for a closer look! [Fung Dong, 2015]Recent studies have shown that a single planet, if it is massive enough, can excite multiple density waves within a protoplanetary disk as it orbits. These density waves can then interfere to produce a multiple-armed spiral structure in the disk inside of the planets orbit a structure which can potentially be observed in scattered-light images of the disk.But what do these arms look like, and what factors determine their structure? In a recently published study, Jeffrey Fung and Ruobing Dong, two researchers at the University of California at Berkeley, have modeled the spiral arms in an effort to answer these questions.Arms Provide AnswersA useful parameter for describing the structure is the azimuthal separation (sep) between the primary and secondary spiral arms. If you draw a circle within the disk and measure the angle between the two points where the primary and secondary arms cross it, thats sep.Azimuthal separation of the primary and secondary spiral arms, as a function of the planet-to-star mass ratio q. The different curves represent different disk aspect ratios. [Fung Dong, 2015]The authors find thatsep stays roughly constant for different radii, but its strongly dependent on the planets mass: for larger planets, sep increases. They discover that sep scales as a power of the planet mass for companions between Neptune mass and 16 Jupiter masses, orbiting around a solar-mass star. For larger, brown-dwarf-size companions, sep is a constant 180.If this new theory is confirmed, it could have very interesting implications for

  15. Let's Grow Old Together: The Simultaneous Evolution of Planet and Host Star

    NASA Astrophysics Data System (ADS)

    Barnett, Megan; Rogers, Leslie

    2017-01-01

    The low-density sub-Neptune sized planets that Kepler found in abundance are intriguing due to their unexpected survival at close orbital separations (a< 1 AU) and their absence from our Solar System. Several of these planets orbit stars that have evolved off the main sequence, or are nearing the end of their main sequence lifetimes (e.g., Kepler-10, Kepler-11, Kepler-36). Previous simulations of sub-Neptune size planet evolution, however, have neglected the changing stellar irradiance incident on the planet. We adapt MESA (Modules for Experiments in Stellar Astrophysics) to evolve low-mass exoplanets with hydrogen-helium envelopes and model how their radii and mass loss rates change as their host stars evolve off the main sequence. We assess the extent to which implementing changing irradiation improves characterization of the possible current and initial compositions of observed exoplanets.

  16. Discovery and characterization of small planets from K2

    NASA Astrophysics Data System (ADS)

    Sinukoff, Evan; Howard, Andrew; Crossfield, Ian; Petigura, Erik; Schlieder, Joshua

    2015-12-01

    In 2014, the Kepler Telescope was repurposed for a new "K2" mission, searching for transiting planets in ~14 fields along the ecliptic, for 80 days each. We are conducting a follow-up program to detect and characterize K2 planets to better understand small planet diversity. I present the detection and confirmation of over 150 transiting planets, mostly sub-Neptune-size, in the first five K2 fields. This includes more than a dozen multi-planet systems, many of which are bright enough for spectroscopic follow-up to measure planet masses via radial velocities (RVs). I report preliminary masses and densities of planets in a few of these new multi-planet systems, constrained by Keck HIRES RVs. Continued RV follow-up will probe the compositional diversity of small planets, examining the degree to which environmental factors (e.g. stellar properties, incident flux, system architectures) sculpt the planet mass-radius diagram.

  17. Measuring the Masses of K2 Planets with HARPS-N to Determine the Conditions Under Which Planets Retain, or Lose, their Primordial Envelopes

    NASA Astrophysics Data System (ADS)

    Lopez-Morales, Mercedes

    One of the main findings of NASA's Kepler Mission has been an abundance of planets with radii between that of Neptune and Earth around solar type stars, the so-called miniNeptunes and super-Earths. There is no equivalent of those planets in our Solar System, but about 80 percent of the candidates in the Kepler catalog are in this size range. Therefore, they appear to be the most common type of planets around solar type stars. In spite of their large numbers, we still know very little about the masses of mini-Neptunes and super-Earths, and their densities. There has been some recent progress on this topic, for e.g. as part of an ongoing XRP proposal (14-XRP14_20071; P.I. Charbonneau), our team has measured precise masses for 8 planets with radii between 1 and 2.5 Earths with HARPS-N, and found that all planets smaller than 1.6 Earth radii have core masses consistent with Earth's, while all planets larger than 1.6 Earth radii have H/He envelopes. The current hypothesis is that this is an insolation effect, since all the rocky planets with precise mass measurements are in very short orbits. However, that hypothesis has not been fully tested, and many other questions about the formation and evolution of these small planets remain unsolved, i.e. what is the rocky/non-rocky ratio of these planets? Are the observed rocky planets evaporated cores of sub-Neptunes, or did they form as bare cores? Can very short period planets retain a significant envelope? Is the currently hypothesized non-rocky/rocky transition at 1.5-1.7 Earth radii real? Precision radial velocity mass measurements so far suffer from an observational bias, in which larger radius planets with small radial velocity signals have been overlooked. These cases would form a population of very low-mass, gaseous planets, which 1) disagree with the current conclusion that all low mass planets below 6 Earth masses are rocky, 2) serve to test current formation/gas accretion and evaporation models, and 3) have large

  18. THE MASS DISTRIBUTION OF SUBGIANT PLANET HOSTS

    SciTech Connect

    Lloyd, James P.

    2013-09-01

    High mass stars are hostile to Doppler measurements due to rotation and activity on the main-sequence, so RV searches for planets around massive stars have relied on evolved stars. A large number of planets have been found around evolved stars with M > 1.5 M{sub Sun }. To test the robustness of mass determinations, Lloyd compared mass distributions of planet hosting subgiants with distributions from integrating isochrones and concluded that it is unlikely the subgiant planet hosts are this massive, but rather that the mass inferences are systematically in error. The conclusions of Lloyd have been called in to question by Johnson et al., who show TRILEGAL-based mass distributions that disagree with the mass distributions in Lloyd, which they attribute to Malmquist bias. Johnson et al. argue that the very small spectroscopic observational uncertainties favor high masses, and there are a large number of high mass sub giants in RV surveys. However, in this Letter, it is shown that Malmquist bias does not impact the mass distributions, but the mass distribution is sensitive to Galaxy model. The relationship needed to reconcile the subgiant planet host masses with any model of the Galactic stellar population is implausible, and the conclusion of Lloyd that spectroscopic mass determinations of subgiants are likely to have been overestimated is robust.

  19. Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets

    NASA Astrophysics Data System (ADS)

    Christiansen, Jessie L.; Vanderburg, Andrew; Burt, Jennifer; Fulton, B. J.; Batygin, Konstantin; Benneke, Björn; Brewer, John M.; Charbonneau, David; Ciardi, David R.; Collier Cameron, Andrew; Coughlin, Jeffrey L.; Crossfield, Ian J. M.; Dressing, Courtney; Greene, Thomas P.; Howard, Andrew W.; Latham, David W.; Molinari, Emilio; Mortier, Annelies; Mullally, Fergal; Pepe, Francesco; Rice, Ken; Sinukoff, Evan; Sozzetti, Alessandro; Thompson, Susan E.; Udry, Stéphane; Vogt, Steven S.; Barman, Travis S.; Batalha, Natasha E.; Bouchy, François; Buchhave, Lars A.; Butler, R. Paul; Cosentino, Rosario; Dupuy, Trent J.; Ehrenreich, David; Fiorenzano, Aldo; Hansen, Brad M. S.; Henning, Thomas; Hirsch, Lea; Holden, Bradford P.; Isaacson, Howard T.; Johnson, John A.; Knutson, Heather A.; Kosiarek, Molly; López-Morales, Mercedes; Lovis, Christophe; Malavolta, Luca; Mayor, Michel; Micela, Giuseppina; Motalebi, Fatemeh; Petigura, Erik; Phillips, David F.; Piotto, Giampaolo; Rogers, Leslie A.; Sasselov, Dimitar; Schlieder, Joshua E.; Ségransan, Damien; Watson, Christopher A.; Weiss, Lauren M.

    2017-09-01

    HD 3167 is a bright (V = 8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 ± 0.38 {M}\\oplus for HD 3167 b, a hot super-Earth with a likely rocky composition ({ρ }b = {5.60}-1.43+2.15 g cm‑3), and {9.80}-1.24+1.30 {M}\\oplus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement ({ρ }c = {1.97}-0.59+0.94 g cm‑3). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 ± 0.045 d (between planets b and c) and a minimum mass of 6.90 ± 0.71 {M}\\oplus . We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.°3 because we do not observe transits of planet d. From 1.°3 to 40°, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time. From 40° to 60°, Kozai–Lidov oscillations increase the system’s instability, but it can remain stable for up to 100 Myr. Above 60°, the system is unstable. HD 3167 promises to be a fruitful system for further study and a preview of the many exciting systems expected from the upcoming NASA TESS mission.

  20. Extrasolar planets around intermediate mass stars

    NASA Astrophysics Data System (ADS)

    Hatzes, A. P.

    2008-08-01

    One of the earliest hints for extrasolar planets came with the discovery almost 15 years ago of low amplitude, long period radial velocity (RV) variations in several K giant stars, β Gem, α Tau (Aldebaran) and α Boo. Since then it has been confirmed that for β Gem (stellar mass =1.7 Modot) these RV variations are due to a planetary companion. Aldebaran is another K giant star showing long-lived (>26 years) and coherent RV variations. These are most likely due to a planetary companion having a mass of 9 MJup using an estimated mass of 2.5 Modot for the star. Giant stars like α Tau and β Gem offer us the possibility of studying the process of planet formation around stars more massive than the sun. The main sequence stars with masses >1.2 Modot are ill-suited for RV surveys as there are few spectral lines for measuring the RV and these are often broadened by high rates of stellar rotation. Currently over 20 intermediate mass giant stars are known to host extrasolar planets. This sample is sufficiently large that we can begin to look at the overall properties of planets around intermediate mass stars. These suggest that more massive stars may have more massive planets that the orbital eccentricities for their extrasolar planets show the wide range of eccentricities seen for main sequence, solar mass stars, and that unlike for main sequence stars there seems to be no preference for metal rich intermediate mass stars to host extrasolar planets.

  1. 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.

  2. Low-mass star and planet formation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1989-01-01

    Low-mass star and planet formation is reviewed through a brief comparison of the results of cosmogonical models with observations ranging from studies of star-forming regions to searches for planetary companions to low-mass stars. Five key phases are described, starting from the dense, interstellar cloud cores that form low-mass stars, through the protostellar collapse and fragmentation phase, to the formation of a protostellar object accreting gas from the surrounding protostellar disk and cloud envelope. Descriptions are given for the phase where planets are formed in the protostellar disk, and the dissipation of the bulk of the protostellar disk and the appearance of an optically visible, premain-sequence star.

  3. WFIRST PLANET MASSES FROM MICROLENS PARALLAX

    SciTech Connect

    Yee, J. C.

    2013-06-20

    I present a method using only a few ground-based observations of magnified microlensing events to routinely measure the parallaxes of WFIRST events if WFIRST is in an L2 orbit. This could be achieved for all events with A{sub max} > 30 using target-of-opportunity observations of select WFIRST events, or with a complementary, ground-based survey of the WFIRST field, which can push beyond this magnification limit. When combined with a measurement of the angular size of the Einstein ring, which is almost always measured in planetary events, these parallax measurements will routinely give measurements of the lens masses and hence the absolute masses of the planets. They can also lead to mass measurements for dark, isolated objects such as brown dwarfs, free-floating planets, and stellar remnants if the size of the Einstein ring is measured.

  4. On the Final Mass of Giant Planets

    NASA Technical Reports Server (NTRS)

    Estrada, P. R.; Mosqueira, I.

    2004-01-01

    In the core accretion model of giant planet formation, when the core reaches critical mass, hydrostatic equilibrium is no longer possible and gas accretion ensues. If the envelope is radiative, the critical core mass is nearly independent of the boundary conditions and is roughly M(sub crit) 10Mass of the Earth (with weak dependence on the rate of planetesimal accretion M(sub core) and the disk opacity k). Given that such a core may form at the present location of Jupiter in a time comparable to its Type I migration time (10(exp 5) - 10(exp 6) years) provided that the nebula was significantly enhanced in solids with respect to the MMSN and stall at this location in a weakly turbulent (alpha approximately less than 10(exp -4) disk, it may be appropriate to assume that such objects inevitably form and drive the evolution of late-phase T Tauri star disks. Here we investigate the final masses of giant planets in disks with one or more than one such cores. Although the presence of several planets would lead to Type II migration (due to the effective viscosity resulting from the planetary tidal torques), we ignore this complication for now and simply assume that each core has stalled at its location in the disk. Once a core has achieved critical mass, its gaseous accretion is governed by the given Kelvin-Helmholtz timescale.

  5. Magnetospheric Truncation, Tidal Inspiral, and the Creation of Short-period and Ultra-short-period Planets

    NASA Astrophysics Data System (ADS)

    Lee, Eve J.; Chiang, Eugene

    2017-06-01

    Sub-Neptunes around FGKM dwarfs are evenly distributed in log orbital period down to ˜10 days, but dwindle in number at shorter periods. Both the break at ˜10 days and the slope of the occurrence rate down to ˜1 day can be attributed to the truncation of protoplanetary disks by their host star magnetospheres at corotation. We demonstrate this by deriving planet occurrence rate profiles from empirical distributions of pre-main-sequence stellar rotation periods. Observed profiles are better reproduced when planets are distributed randomly in disks—as might be expected if planets formed in situ—rather than piled up near disk edges, as would be the case if they migrated in by disk torques. Planets can be brought from disk edges to ultra-short (<1 day) periods by asynchronous equilibrium tides raised on their stars. Tidal migration can account for how ultra-short-period planets are more widely spaced than their longer-period counterparts. Our picture provides a starting point for understanding why the sub-Neptune population drops at ˜10 days regardless of whether the host star is of type FGK or early M. We predict planet occurrence rates around A stars to also break at short periods, but at ˜1 day instead of ˜10 days because A stars rotate faster than stars with lower masses (this prediction presumes that the planetesimal building blocks of planets can drift inside the dust sublimation radius).

  6. The mass distribution function of planets in the Galaxy

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    2016-05-01

    I will describe some deductions about the planet mass function from the observational data of exoplanets and theoretical considerations of dynamical stability of planetary systems. The Kepler mission has carried out a systematic survey for planets in the Galaxy, and obtained data on several hundred exo-planetary systems. Analysis of these data indicates that planetary orbital separations have an approximately log-normal distribution. Taken together with plausible ansatzs for the dynamical stability of multi-planet systems, it appears that the planet mass function is peaked in logarithm of mass, with the most probable value of log m/M_Earth ˜ (0.6 - 1.0). A modest extrapolation finds that Earth mass planets are about ~1000 times more common than Jupiter mass planets, and that the most common planets in the Galaxy may be of lunar-to-Mars mass.This research was supported by NSF (grant AST-1312498) and NASA (grant NNX14AG93G).

  7. On the mass and orbit of the ninth planet

    NASA Astrophysics Data System (ADS)

    Ugwoke, Azubike Christian

    2016-07-01

    ON THE MASS AND ORBIT OF THE NINTH PLANET A new planet is currently being proposed in the literature.This yet to be observed planet has its mass and orbit yet to be determined. However, if this planet is to escape being labelled a plutinoid, it must posses all the characteristics of a planet as currently set by the IAU. In addition it must be massive enough to enable it couple into the gravitational potential of the sun. Our earlier paper on this issue has suggested that no new planets are expected beyond Neptune , due to the vanishing gravitational potential of the sun within that orbit.Any new planet must be indeed very massive to be gravitationally linked sufficiently to the sun. In the current paper we have obtained estimates for planet 9 orbit and mass using this method.

  8. The mass of dwarf planet Eris.

    PubMed

    Brown, Michael E; Schaller, Emily L

    2007-06-15

    The discovery of dwarf planet Eris was followed shortly by the discovery of its satellite, Dysnomia, but the satellite orbit, and thus the system mass, was not known. New observations with the Keck Observatory and the Hubble Space Telescopes show that Dysnomia has a circular orbit with a radius of 37,350 +/- 140 (1-sigma) kilometers and a 15.774 +/- 0.002 day orbital period around Eris. These orbital parameters agree with expectations for a satellite formed out of the orbiting debris left from a giant impact. The mass of Eris from these orbital parameters is 1.67 x 10(22) +/- 0.02 x 10(22) kilograms, or 1.27 +/- 0.02 that of Pluto.

  9. Exceptional Stars Origins, Companions, Masses and Planets

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.; Hansen, Bradley M. S.; Phinney, Sterl; vanKerkwijk, Martin H.; Vasisht, Gautam

    2004-01-01

    As SIM Interdisciplinary Scientist, we will study the formation, nature and planetary companions of the exotic endpoints of stellar evolution. Our science begins with stars evolving from asymptotic branch giants into white dwarfs. We will determine the parallax and orbital inclination of several iron-deficient post-AGB stars, who peculiar abundances and infrared excesses are evidence that they are accreting gas depleted of dust from a circumbinary disk. Measurement of the orbital inclination, companion mass arid parallax will provide critical constraints. One of these stars is a prime candidate for trying nulling observations, which should reveal light reflected from both the circumbinary and Roche disks. The circumbinary disks seem favorable sites for planet formation. Next, we will search for planets around white dwarfs, both survivors froni the main-sequence stage, and ones newly formed from the circumbinary disks of post-AGB binaries or in white dwarf mergers. Moving up in mass, we will measure the orbital reflex of OB/Be companions to pulsars, determine natal kicks and presupernova orbits, and expand the sample of well-determined neutron star masses. We will obtain the parallax of a transient X-ray binary, whose quiescent emission may be thermal emission from the neutron star, aiming for precise measurement of the neutron star radius. Finally, black holes. We will measure the reflex motions of the companion of what appear to be the most massive stellar black holes. The visual orbits will determine natal kicks, and test the assumptions underlying mass estimates made from the radial velocity curves, projected rotation, and ellipsoidal variations. In addition, we will attempt to observe the visual orbit of SS 433, as well as the proper motion of the emission line clumps in its relativistic jets. Additional information is included in the original document.

  10. Exceptional Stars Origins, Companions, Masses and Planets

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.; Hansen, Bradley M. S.; Phinney, Sterl; vanKerkwijk, Martin H.; Vasisht, Gautam

    2004-01-01

    As SIM Interdisciplinary Scientist, we will study the formation, nature and planetary companions of the exotic endpoints of stellar evolution. Our science begins with stars evolving from asymptotic branch giants into white dwarfs. We will determine the parallax and orbital inclination of several iron-deficient post-AGB stars, who peculiar abundances and infrared excesses are evidence that they are accreting gas depleted of dust from a circumbinary disk. Measurement of the orbital inclination, companion mass arid parallax will provide critical constraints. One of these stars is a prime candidate for trying nulling observations, which should reveal light reflected from both the circumbinary and Roche disks. The circumbinary disks seem favorable sites for planet formation. Next, we will search for planets around white dwarfs, both survivors froni the main-sequence stage, and ones newly formed from the circumbinary disks of post-AGB binaries or in white dwarf mergers. Moving up in mass, we will measure the orbital reflex of OB/Be companions to pulsars, determine natal kicks and presupernova orbits, and expand the sample of well-determined neutron star masses. We will obtain the parallax of a transient X-ray binary, whose quiescent emission may be thermal emission from the neutron star, aiming for precise measurement of the neutron star radius. Finally, black holes. We will measure the reflex motions of the companion of what appear to be the most massive stellar black holes. The visual orbits will determine natal kicks, and test the assumptions underlying mass estimates made from the radial velocity curves, projected rotation, and ellipsoidal variations. In addition, we will attempt to observe the visual orbit of SS 433, as well as the proper motion of the emission line clumps in its relativistic jets. Additional information is included in the original document.

  11. Kepler Planet Masses and Eccentricities from TTV Analysis

    NASA Astrophysics Data System (ADS)

    Hadden, Sam; Lithwick, Yoram

    2017-07-01

    We conduct a uniform analysis of the transit timing variations (TTVs) of 145 planets from 55 Kepler multiplanet systems to infer planet masses and eccentricities. Eighty of these planets do not have previously reported mass and eccentricity measurements. We employ two complementary methods to fit TTVs: Markov chain Monte Carlo simulations based on N-body integration, and an analytic fitting approach. Mass measurements of 49 planets, including 12 without previously reported masses, meet our criterion for classification as robust. Using mass and radius measurements, we infer the masses of planets’ gaseous envelopes for both our TTV sample and transiting planets with radial velocity observations. Insight from analytic TTV formulae allows us to partially circumvent degeneracies inherent to inferring eccentricities from TTV observations. We find that planet eccentricities are generally small, typically a few percent, but in many instances are nonzero.

  12. Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets

    NASA Astrophysics Data System (ADS)

    Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Rowe, Jason F.; Jenkins, Jon M.; Bryson, Stephen T.; Latham, David W.; Howell, Steve B.; Gautier, Thomas N., III; Batalha, Natalie M.; Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Gilliland, Ronald L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Huber, Daniel; Chaplin, William J.; Basu, Sarbani; Buchhave, Lars A.; Quinn, Samuel N.; Borucki, William J.; Koch, David G.; Hunter, Roger; Caldwell, Douglas A.; Van Cleve, Jeffrey; Kolbl, Rea; Weiss, Lauren M.; Petigura, Erik; Seager, Sara; Morton, Timothy; Johnson, John Asher; Ballard, Sarah; Burke, Chris; Cochran, William D.; Endl, Michael; MacQueen, Phillip; Everett, Mark E.; Lissauer, Jack J.; Ford, Eric B.; Torres, Guillermo; Fressin, Francois; Brown, Timothy M.; Steffen, Jason H.; Charbonneau, David; Basri, Gibor S.; Sasselov, Dimitar D.; Winn, Joshua; Sanchis-Ojeda, Roberto; Christiansen, Jessie; Adams, Elisabeth; Henze, Christopher; Dupree, Andrea; Fabrycky, Daniel C.; Fortney, Jonathan J.; Tarter, Jill; Holman, Matthew J.; Tenenbaum, Peter; Shporer, Avi; Lucas, Philip W.; Welsh, William F.; Orosz, Jerome A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.; Stello, D.; White, T. R.; Boss, Alan; Devore, Edna; Gould, Alan; Prsa, Andrej; Agol, Eric; Barclay, Thomas; Coughlin, Jeff; Brugamyer, Erik; Mullally, Fergal; Quintana, Elisa V.; Still, Martin; Thompson, Susan E.; Morrison, David; Twicken, Joseph D.; Désert, Jean-Michel; Carter, Josh; Crepp, Justin R.; Hébrard, Guillaume; Santerne, Alexandre; Moutou, Claire; Sobeck, Charlie; Hudgins, Douglas; Haas, Michael R.; Robertson, Paul; Lillo-Box, Jorge; Barrado, David

    2014-02-01

    We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O). Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology.

  13. Orbital migration of giant planets induced by gravitationally unstable gaps: the effect of planet mass

    NASA Astrophysics Data System (ADS)

    Cloutier, Ryan; Lin, Min-Kai

    2013-09-01

    It has been established that self-gravitating disc-satellite interaction can lead to the formation of a gravitationally unstable gap. Such an instability may significantly affect the orbital migration of gap-opening perturbers in self-gravitating discs. In this paper, we extend the two-dimensional hydrodynamic simulations of Lin & Papaloizou to investigate the role of the perturber or planet mass on the gravitational stability of gaps and its impact on orbital migration. We consider giant planets with planet-to-star mass ratio q ≡ Mp/M* ∈ [0.3, 3.0] × 10-3 (so that q = 10-3 corresponds to a Jupiter mass planet if M* = M⊙), in a self-gravitating disc with disc-to-star mass ratio Md/M* = 0.08, aspect ratio h = 0.05 and Keplerian Toomre parameter Qk0 = 1.5 at 2.5 times the planet's initial orbital radius. These planet masses correspond to tilde{q}in [0.9, 1.7], where tilde{q} is the ratio of the planet Hill radius to the local disc scale-height. Fixed-orbit simulations show that all planet masses we consider open gravitationally unstable gaps, but the instability is stronger and develops sooner with increasing planet mass. The disc-on-planet torques typically become more positive with increasing planet mass. In freely migrating simulations, we observe faster outward migration with increasing planet mass, but only for planet masses capable of opening unstable gaps early on. For q = 0.0003 (tilde{q}=0.9), the planet undergoes rapid inward type III migration before it can open a gap. For q = 0.0013 (tilde{q}=1.5) we find it is possible to balance the tendency for inward migration by the positive torques due to an unstable gap, but only for a few 10 s of orbital periods. We find the unstable outer gap edge can trigger outward type III migration, sending the planet to twice its initial orbital radius on dynamical time-scales. We briefly discuss the importance of our results in the context of giant planet formation on wide orbits through disc fragmentation.

  14. Mass Determination Of Directly Imaged Planet Candidates

    NASA Astrophysics Data System (ADS)

    Schmidt, Tobias; Neuhauser, R.; Seifahrt, A.

    2011-09-01

    About 20 sub-stellar companions with large separations (> 50 AU) to their young primary stars and brown dwarfs are confirmed by both common proper motion and late-M / early-L type spectra. The origin and early evolution of these objects is still under debate. While often these sub-stellar companions are regarded as brown dwarfs, they could possibly also be massive planets, the mass estimates are very uncertain so far. They are companions to primary stars or brown dwarfs in young associations and star forming regions like Taurus, Upper Scorpius, the TW Hya association, Beta Pic moving group, TucHor association, Lupus, Ophiuchus, and Chamaeleon, hence their ages and distances are well known, in contrast to free-floating brown dwarfs. Here we present how mass estimates of such young directly imaged companions can be derived, using e.g. evolutionary models, which are however currently almost uncalibrated by direct mass measurements of young objects. An empirical classification by medium-resolution spectroscopy is currently not possible, because a spectral sequence that is taking the lower gravity into account, is not existing. This problem leads to an apparent mismatch between spectra of old field type objects and young low-mass companions at the same effective temperature, hampering a determination of temperature and surface gravity independent from models. We show that from spectra of the objects, using the advantages of light concentration by an AO-assisted integral field spectrograph, temperature, extinction, metallicity and surface gravity can be derived using non-equilibrium radiative transfer atmosphere models as comparison and that this procedure as well allows a mass determination in combination with the luminosities found by the direct observations, as has recently been done by us for several young sub-stellar companions, as e.g. GQ Lup, CT Cha or UScoCTIO 108.

  15. New Insights on Planet Formation in WASP-47 from a Simultaneous Analysis of Radial Velocities and Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Weiss, Lauren M.; Deck, Katherine M.; Sinukoff, Evan; Petigura, Erik A.; Agol, Eric; Lee, Eve J.; Becker, Juliette C.; Howard, Andrew W.; Isaacson, Howard; Crossfield, Ian J. M.; Fulton, Benjamin J.; Hirsch, Lea; Benneke, Björn

    2017-06-01

    Measuring precise planet masses, densities, and orbital dynamics in individual planetary systems is an important pathway toward understanding planet formation. The WASP-47 system has an unusual architecture that motivates a complex formation theory. The system includes a hot Jupiter (“b”) neighbored by interior (“e”) and exterior (“d”) sub-Neptunes, and a long-period eccentric giant planet (“c”). We simultaneously modeled transit times from the Kepler K2 mission and 118 radial velocities to determine the precise masses, densities, and Keplerian orbital elements of the WASP-47 planets. Combining RVs and TTVs provides a better estimate of the mass of planet d (13.6+/- 2.0 {M}\\oplus ) than that obtained with only RVs (12.75+/- 2.70 {M}\\oplus ) or TTVs (16.1+/- 3.8 {M}\\oplus ). Planets e and d have high densities for their size, consistent with a history of photoevaporation and/or formation in a volatile-poor environment. Through our RV and TTV analysis, we find that the planetary orbits have eccentricities similar to the solar system planets. The WASP-47 system has three similarities to our own solar system: (1) the planetary orbits are nearly circular and coplanar, (2) the planets are not trapped in mean motion resonances, and (3) the planets have diverse compositions. None of the current single-process exoplanet formation theories adequately reproduce these three characteristics of the WASP-47 system (or our solar system). We propose that WASP-47, like the solar system, formed in two stages: first, the giant planets formed in a gas-rich disk and migrated to their present locations, and second, the high-density sub-Neptunes formed in situ in a gas-poor environment.

  16. Detecting Earth-Mass Planets with Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; Rhie, Sun Hong

    1996-11-01

    We show that Earth-mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in the Galactic bulge. The star and its planet act as a binary lens which generates a light curve that can differ substantially from the light curve due only to the star itself. We show that the planetary signal remains detectable for planetary masses as small as an Earth mass when realistic source star sizes are included in the light curve calculation. These planets are detectable if they reside in the "lensing zone," which is centered between 1 and 4 AU from the lensing star and spans about a factor of 2 in distance. If we require a minimum deviation of 4% from the standard point-lens microlensing light curve, then we find that more than 2% of all M⊕ planets and 10% of all 10 M⊕ in the lensing zone can be detected. If a third of all lenses have no planets, a third have 1 M⊕ planets, and the remaining third have 10 M⊕ planets then we estimate that an aggressive ground-based microlensing planet search program could find one Earth-mass planet and half a dozen 10 M⊕ planets per year.

  17. Formation and composition of planets around very low mass stars

    NASA Astrophysics Data System (ADS)

    Alibert, Y.; Benz, W.

    2017-01-01

    Context. The recent detection of planets around very low mass stars raises the question of the formation, composition, and potential habitability of these objects. Aims: We use planetary system formation models to infer the properties, in particular their radius distribution and water content, of planets that may form around stars ten times less massive than the Sun. Methods: Our planetary system formation and composition models take into account the structure and evolution of the protoplanetary disk, the planetary mass growth by accretion of solids and gas, as well as planet-planet, planet-star, and planet-disk interactions. Results: We show that planets can form at small orbital period in orbit about low-mass stars. We show that the radius of the planets is peaked at about 1 R⊕ and that they are, in general, volatile rich especially if proto-planetary disks orbiting this type of stars are long lived. Conclusions: Close-in planets orbiting low-mass stars similar in terms of mass and radius to those recently detected can be formed within the framework of the core-accretion paradigm as modeled here. The properties of protoplanetary disks, and their correlation with the stellar type, are key to understand their composition.

  18. A STELLAR-MASS-DEPENDENT DROP IN PLANET OCCURRENCE RATES

    SciTech Connect

    Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

    2015-01-10

    The Kepler spacecraft has discovered a large number of planets with up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with effective temperatures as low as 2500 K, which corresponds to M stars. These cooler stars allow characterization of small planets near the habitable zone, yet it is not clear if this population is representative of that around FGK stars. In this paper, we calculate the occurrence of planets around stars of different spectral types as a function of planet radius and distance from the star and show that they are significantly different from each other. We further identify two trends. First, the occurrence of Earth- to Neptune-sized planets (1-4 R {sub ⊕}) is successively higher toward later spectral types at all orbital periods probed by Kepler; planets around M stars occur twice as frequently as around G stars, and thrice as frequently as around F stars. Second, a drop in planet occurrence is evident at all spectral types inward of a ∼10 day orbital period, with a plateau further out. By assigning to each spectral type a median stellar mass, we show that the distance from the star where this drop occurs is stellar mass dependent, and scales with semi-major axis as the cube root of stellar mass. By comparing different mechanisms of planet formation, trapping, and destruction, we find that this scaling best matches the location of the pre-main-sequence co-rotation radius, indicating efficient trapping of migrating planets or planetary building blocks close to the star. These results demonstrate the stellar-mass dependence of the planet population, both in terms of occurrence rate and of orbital distribution. The prominent stellar-mass dependence of the inner boundary of the planet population shows that the formation or migration of planets is sensitive to the stellar parameters.

  19. 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.

  20. Instability of mass transfer in a planet-star system

    NASA Astrophysics Data System (ADS)

    Jia, Shi; Spruit, H. C.

    2017-02-01

    We show that the angular momentum exchange mechanism governing the evolution of mass-transferring binary stars does not apply to Roche lobe filling planets, because most of the angular momentum of the mass-transferring stream is absorbed by the host star. Apart from a correction for the difference in specific angular momentum of the stream and the centre of mass of the planet, the orbit does not expand much on Roche lobe overflow. We explore the conditions for dynamically unstable Roche lobe overflow as a function of planetary mass and mass and radius (age) of host star and equation of state of planet. For a Sun-like host, gas giant planets in a range of mass and entropy can undergo dynamical mass transfer. Examples of the evolution of the mass transfer process are given. Dynamic mass transfer of rocky planets depends somewhat sensitively on equation of state used. Silicate planets in the range 1 < Mp < 10 M⊕ typically go through a phase of dynamical mass transfer before settling to slow overflow when their mass drops to less than 1 M⊕.

  1. 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.

  2. A Large Hubble Space Telescope Survey of Low-Mass Exoplanets

    NASA Astrophysics Data System (ADS)

    Benneke, Björn; Crossfield, Ian; Knutson, Heather; Lothringer, Joshua; McCullough, Peter R.; Dragomir, Diana; Morley, Caroline; Kempton, Eliza

    2016-10-01

    The discovery of short-period planets with masses and radii between Earth and Neptune was one of the biggest surprises in the brief history of exoplanet science. From the Kepler mission, we know that these "super-Earths" or "sub-Neptunes" orbit at least 40% of stars, likely representing the most common outcome of planet formation. Despite this ubiquity, we know little about their typical compositions and formation histories. In this talk, we will shed new light on these worlds by presenting the multiple the main results from our 124-orbit HST transit spectroscopy survey to probe the chemical compositions of low-mass exoplanets. We will report on multiple molecular detections. Our unprecedented HST survey provides the first comprehensive look at this intriguing new class of planets by covering seven planets ranging from 1 Neptune mass and temperatures close to 2000K to a 1 Earth-mass planet near the habitable zone of its host star.

  3. Microlensing Discovery of an Earth-Mass Planet

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-04-01

    What do we know about planet formation around stars that are so light that they cant fuse hydrogen in their cores? The new discovery of an Earth-mass planet orbiting what is likely a brown dwarf may help us better understand this process.Planets Around Brown Dwarfs?Comparison of the sizes of the Sun, a low-mass star, a brown dwarf, Jupiter, and Earth. [NASA/JPL-Caltech/UCB]Planets are thought to form from the material inprotoplanetary disks around their stellar hosts. But the lowest-mass end of the stellar spectrum brown dwarfs, substellar objects so light that they straddle the boundary between planet and star will have correspondingly light disks. Do brown dwarfs disks typically have enough mass to form Earth-mass planets?To answer this question, scientists have searched for planets around brown dwarfs with marginal success. Thus far, only four such planets have been found and these systems may not be typical, since they were discovered via direct imaging. To build a more representative sample, wed like to discover exoplanets around brown dwarfs via a method that doesnt rely on imaging the faint light of the system.A diagram of how planets are detected via gravitational microlensing. The detectable planet is in orbit around the foreground lens star. [NASA]Lensed Light as a GiveawayConveniently, such a method exists and its recently been used to make a major discovery! The planet OGLE-2016-BLG-1195Lb was detected as a result of a gravitational microlensing event that was observed both from the ground and from space.The discovery of a planet via microlensing occurs when the light of a distant source star is magnified by a passing foreground star hosting a planet. The light curve of the source shows a distinctive magnification signature as a result of the gravitational lensing from the foreground star, and the gravitational field of the lensing stars planet can add its own detectable blip to the curve.OGLE-2016-BLG-1195LbThe magnification curve of OGLE-2016-BLG-1195

  4. Fu Ori outbursts and the planet-disc mass exchange

    NASA Astrophysics Data System (ADS)

    Nayakshin, Sergei; Lodato, Giuseppe

    2012-10-01

    It has been recently proposed that giant protoplanets migrating inwards through the disc more rapidly than they contract could be tidally disrupted when they fill their Roche lobes ˜0.1 au away from their parent protostars. Here we consider the process of mass and angular momentum exchange between the tidally disrupted planet and the surrounding disc in detail. We find that the planet's adiabatic mass-radius relation and its ability to open a deep gap in the disc determine whether the disruption proceeds as a sudden runaway or a balanced quasi-static process. In the latter case, the planet feeds the inner disc through its Lagrangian L1 point like a secondary star in a stellar binary system. As the planet loses mass, it gains specific angular momentum and normally migrates in the outward direction until the gap closes. Numerical experiments show that planet disruption outbursts are preceded by long 'quiescent' periods during which the disc inward of the planet is empty. The hole in the disc is created when the planet opens a deep gap, letting the inner disc to drain on to the star while keeping the outer one stalled behind the planet. We find that the mass-losing planet embedded in a realistic protoplanetary disc spawns an extremely rich set of variability patterns. In a subset of parameter space, there is a limit cycle behaviour caused by non-linear interaction between the planet mass-loss and the disc hydrogen ionization instability. We suggest that tidal disruptions of young massive planets near their stars may be responsible for the observed variability of young accreting protostars such as FU Ori, EXor and T Tauri stars in general.

  5. Characterizing Low-Mass Planets in Kepler's Multi-Planet Systems with Transit Timing

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Lissauer, Jack; Rowe, Jason; Fabrycky, Daniel

    2014-11-01

    The Kepler mission has revealed an abundance of planets in a regime of mass and size that is absent from the Solar System. This includes systems of high multiplicity within 1 AU, where low-mass volatile-rich planets have been observed in compact orbital configurations. Smaller, rocky planets have also been observed in such systems. The existing sample of characterized planets on the mass-radius diagram shows no abrupt transition from rocky planets to those that must be volatile-rich, but characteristic trends are beginning to emerge. More precise characterizations of planets by mass, radius, and incident flux will aid in revealing fundamental properties of a common class of exoplanets. There is a small sample of exoplanets with known masses and radii, mostly hot jupiters whose radii are known from transit depths, and whose masses are determined from radial velocity spectroscopy (RV). In the absence of mass determinations via RV observations, transit timing variations (TTVs) offer a chance to probe perturbations between planets that pass close to one another or are near resonance, and hence dynamical fits to observed transit times can be used to measure planetary masses and orbital parameters. Such modelling with Kepler data probes planetary masses over orbital periods ranging from ~5-100 days, complementing the sample of RV detections. Furthermore, in select cases, dynamical fits to observed TTVs can tightly constrain the orbital eccentricity vectors, which can, alongside the transit light curve, tightly constrain the density and radius of the host star, and hence reduce the uncertainty on planetary radius. TTV studies have revealed a class of low-mass low-density objects with a substantial mass fraction in the form of a voluminous H-rich atmosphere. To these we add precise mass measurements of the outer planets of Kepler-33, a compact system with five known transiting planets, three of which show detectable transit timing variations. These results will be placed

  6. Trapping planets in an evolving protoplanetary disk: preferred time, locations, and planet mass

    NASA Astrophysics Data System (ADS)

    Baillié, K.; Charnoz, S.; Pantin, E.

    2016-05-01

    Context. Planet traps are necessary to prevent forming planets from falling onto their host star by type I inward migration. Surface mass density and temperature gradient irregularities favor the apparition of traps (planet accumulation region) and deserts (planet depletion zone). These features are found at the dust sublimation lines and heat transition barriers. Aims: We study how planets may remain trapped or escape these traps as they grow and as the disk evolves viscously with time. Methods: We numerically model the temporal viscous evolution of a protoplanetary disk by coupling its dynamics, thermodynamics, geometry, and composition. The resulting midplane density and temperature profiles allow the modeling of the interactions of this type of evolving disk with potential planets, even before the steady state is reached. Results: We follow the viscous evolution of a minimum mass solar nebula and compute the Lindblad and corotation torques that this type of disk would exert on potential planets of various masses that are located within the planetary formation region. We determine the position of planet traps and deserts in relationship with the sublimation lines, shadowed regions, and heat transition barriers. We notice that the planet mass affects the trapping potential of the mentioned structures through the saturation of the corotation torque. Planets that are a few tens of Earth masses can be trapped at the sublimation lines until they reach a certain mass while planets that are more massive than 100 M⊕ can only be trapped permanently at the heat transition barriers. They may also open gaps beyond 5 au and enter type II migration. Conclusions: Coupling a bimodal planetary migration model with a self-consistent evolved disk, we were able to distinguish several potential planet populations after five million years of evolution: two populations of giant planets that could stay trapped around 5.5 and 9 au and possibly open gaps, some super-Earths trapped

  7. Inferring Planet Mass from Spiral Structures in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Fung, Jeffrey; Dong, Ruobing

    2015-12-01

    Recent observations of protoplanetary disk have reported spiral structures that are potential signatures of embedded planets, and modeling efforts have shown that a single planet can excite multiple spiral arms, in contrast to conventional disk-planet interaction theory. Using two and three-dimensional hydrodynamics simulations to perform a systematic parameter survey, we confirm the existence of multiple spiral arms in disks with a single planet, and discover a scaling relation between the azimuthal separation of the primary and secondary arm, {φ }{{sep}}, and the planet-to-star mass ratio q: {φ }{{sep}}=102^\\circ {(q/0.001)}0.2 for companions between Neptune mass and 16 Jupiter masses around a 1 solar mass star, and {φ }{{sep}}=180^\\circ for brown dwarf mass companions. This relation is independent of the disk’s temperature, and can be used to infer a planet’s mass to within an accuracy of about 30% given only the morphology of a face-on disk. Combining hydrodynamics and Monte-Carlo radiative transfer calculations, we verify that our numerical measurements of {φ }{{sep}} are accurate representations of what would be measured in near-infrared scattered light images, such as those expected to be taken by Gemini/GPI, Very Large Telescope/SPHERE, or Subaru/SCExAO in the future. Finally, we are able to infer, using our scaling relation, that the planet responsible for the spiral structure in SAO 206462 has a mass of about 6 Jupiter masses.

  8. Atmospheric circulations of terrestrial planets orbiting low mass stars

    NASA Astrophysics Data System (ADS)

    Edson, Adam Robert

    Atmospheres of planets orbiting low mass stars have properties unlike those typically studied by climatologists. One of the most glaring differences is that the rotation is "trapped" for planets orbiting within the habitable zone of the star. This lack of a typical "day" changes these planets' dynamics. Previous work includes that of Gareth Williams and Manoj Joshi. Joshi discussed planets with 10-day orbits only. Williams focused on planets with differing rotation rates, but still rotating relative to their star. Here, tidally locked planets with a variety of orbital periods ranging from 1 to 100 days are discussed. The GENESIS model is used to simulate these planets, and the data are analyzed for waves, energy fluxes, and habitability. The major components of the energy fluxes are the mean meridional circulation (i.e., the Hadley cell) and stationary eddies in the form of a wave number 1 stationary Rossby wave. A transition point in the atmospheric circulation is identified for orbital periods between 100 hours and 101 hours for dry planets. For the wet planets, the transition occurs near 96-hour rotation period. This transition occurs when the Rossby radius of deformation approaches the planet's radius and is associated with the increasing importance of the wave number two stationary eddy as the Rossby radius approaches the planetary radius. The most habitable dry planet is found to be the 2400-hour orbiter. For the wet planets, the 24-hour rotator is most habitable. The most habitable wet planet is the 24-hour rotator, with the least habitable wet planet being the 2400-hour rotator. The difference in the rotation period of the most habitable planets between the dry planets and the wet planets is caused by the availability of water vapor as a greenhouse gas, the added heat transport through sea ice movement, and the larger heat capacity for the wet planets. When realistic planets are modeled, the habitable surface area and average surface temperature is

  9. 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 ≲ 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 ∝ 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 = CMα Pβ d 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 ≳300 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

  10. Dawes Review 7: The Tidal Downsizing Hypothesis of Planet Formation

    NASA Astrophysics Data System (ADS)

    Nayakshin, Sergei

    2017-01-01

    Tidal Downsizing scenario of planet formation builds on ideas proposed by Gerard Kuiper in 1951. Detailed simulations of self-gravitating discs, gas fragments, dust grain dynamics, and planet evolutionary calculations are summarised here and used to build a predictive population synthesis. A new interpretation of exoplanetary and debris disc data, the Solar System's origins, and the links between planets and brown dwarfs is offered. Tidal Downsizing predicts that presence of debris discs, sub-Neptune mass planets, planets more massive than 5 Jupiter masses and brown dwarfs should not correlate strongly with the metallicity of the host. For gas giants of Saturn to a few Jupiter mass, a strong host star metallicity correlation is predicted only inwards of a few AU from the host. Composition of massive cores is predicted to be dominated by rock rather than ices. Debris discs made by Tidal Downsizing have an innermost edge larger than about 1 au, have smaller total masses and are usually in a dynamically excited state. Planet formation in surprisingly young or very dynamic systems such as HL Tau and Kepler-444 may be a signature of Tidal Downsizing. Open questions and potential weaknesses of the hypothesis are pointed out.

  11. Changes in One Planet's Mass or Semi-Major Axis Affects All Planets' Eccentricities

    NASA Astrophysics Data System (ADS)

    Van Laerhoven, Christa L.; Greenberg, R.

    2012-10-01

    If one or more of the planets in a system ungoes gradual change in either semi-major axis (e.g. by tides) or mass (e.g. by evaporation of a close-in planet) the underlying secular dynamics of the system change, such that the orbital eccentricities of all the planets are affected. In a non-resonant multi-planet system each planet's eccentricity is a sum of eigenmodes, described by classical secular theory. The planets' masses m and semi-major axes a set the underlying structure of the eigenmodes, while the eccentricities e and longitudes of pericenter set the modes' amplitudes and phases. If a physical process (whatever it may physically be) changes only an m or a value, but not e, the underlying eigenmode structure will change, and also the eigenmode amplitudes (and phases) will respond. Thus, this process will change the range of values that each planet's eccentricity will take over a secular cycle, and how quickly secular eccentricity variation happens. Wu and Goldreich (ApJ 564, 1024, 2002) developed a theory that incorporates changing semi-major axis into secular theory, but an implicit assumption of their analysis was that only a single eigenmode has non-zero amplitude. Therefore, that result can only be applied to a system that has already damped to a “quasi-fixed-point”, not to its interesting previous evolution; moreover, Van Laerhoven and Greenberg (C.M.&Dyn.Astr., 113, 215, 2012) showed that in the context of tidal evolution there are often modes that damp on similar timescales so there may be several long-lived eigenmodes. To address this issue, we have developed formulae to describe the more general solution for a system of any number of planets with multiple active eigenmodes incorporating externally driven change in any semi-major axis or mass. Such effects may have significant implications for some multi-planet systems.

  12. EXTRACTING PLANET MASS AND ECCENTRICITY FROM TTV DATA

    SciTech Connect

    Lithwick, Yoram; Xie Jiwei; Wu Yanqin

    2012-12-20

    Most planet pairs in the Kepler data that have measured transit time variations (TTVs) are near first-order mean-motion resonances. We derive analytical formulae for their TTV signals. We separate planet eccentricity into free and forced parts, where the forced part is purely due to the planets' proximity to resonance. This separation yields simple analytical formulae. The phase of the TTV depends sensitively on the presence of free eccentricity: if the free eccentricity vanishes, the TTV will be in phase with the longitude of conjunctions. This effect is easily detectable in current TTV data. The amplitude of the TTV depends on planet mass and free eccentricity, and it determines planet mass uniquely only when the free eccentricity is sufficiently small. We analyze the TTV signals of six short-period Kepler pairs. We find that three of these pairs (Kepler 18, 24, 25) have a TTV phase consistent with zero. The other three (Kepler 23, 28, 32) have small TTV phases, but ones that are distinctly non-zero. We deduce that the free eccentricities of the planets are small, {approx}< 0.01, but not always vanishing. Furthermore, as a consequence of this, we deduce that the true masses of the planets are fairly accurately determined by the TTV amplitudes, within a factor of {approx}< 2. The smallness of the free eccentricities suggests that the planets have experienced substantial dissipation. This is consistent with the hypothesis that the observed pile-up of Kepler pairs near mean-motion resonances is caused by resonant repulsion. But the fact that some of the planets have non-vanishing free eccentricity suggests that after resonant repulsion occurred there was a subsequent phase in the planets' evolution when their eccentricities were modestly excited, perhaps by interplanetary interactions.

  13. Dynamical corotation torques on low-mass planets

    NASA Astrophysics Data System (ADS)

    Paardekooper, S.-J.

    2014-11-01

    We study torques on migrating low-mass planets in locally isothermal discs. Previous work on low-mass planets generally kept the planet on a fixed orbit, after which the torque on the planet was measured. In addition to these static torques, when the planet is allowed to migrate it experiences dynamical torques, which are proportional to the migration rate and whose sign depends on the background vortensity gradient. We show that in discs a few times more massive than the minimum-mass solar nebula, these dynamical torques can have a profound impact on planet migration. Inward migration can be slowed down significantly, and if static torques lead to outward migration, dynamical torques can take over, taking the planet beyond zero-torque lines set by saturation of the corotation torque in a runaway fashion. This means that the region in non-isothermal discs, where outward migration is possible, can be larger than what would be concluded from static torques alone.

  14. MASSES, RADII, AND CLOUD PROPERTIES OF THE HR 8799 PLANETS

    SciTech Connect

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard E-mail: dsaumon@lanl.gov E-mail: andrew.ackerman@nasa.gov E-mail: freedman@darkstar.arc.nasa.gov

    2012-08-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Some studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here, we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against observations of field L and T dwarfs, including the reddest L dwarfs. Unlike some previous studies, we require mutually consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure thus yields plausible values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are not unusual but rather follow previously recognized trends, including a gravity dependence on the temperature of the L to T spectral transition-some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to whether or not we include the H- and the K-band spectrum in our analysis. Solutions for planets c and d are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that, like in L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present an exploratory evolution calculation that accounts for this effect. Finally we recompute the bolometric luminosity of all three planets.

  15. A common mass scaling for satellite systems of gaseous planets.

    PubMed

    Canup, Robin M; Ward, William R

    2006-06-15

    The Solar System's outer planets that contain hydrogen gas all host systems of multiple moons, which notably each contain a similar fraction of their respective planet's mass (approximately 10(-4)). This mass fraction is two to three orders of magnitude smaller than that of the largest satellites of the solid planets (such as the Earth's Moon), and its common value for gas planets has been puzzling. Here we model satellite growth and loss as a forming giant planet accumulates gas and rock-ice solids from solar orbit. We find that the mass fraction of its satellite system is regulated to approximately 10(-4) by a balance of two competing processes: the supply of inflowing material to the satellites, and satellite loss through orbital decay driven by the gas. We show that the overall properties of the satellite systems of Jupiter, Saturn and Uranus arise naturally, and suggest that similar processes could limit the largest moons of extrasolar Jupiter-mass planets to Moon-to-Mars size.

  16. Forecaster: Mass and radii of planets predictor

    NASA Astrophysics Data System (ADS)

    Chen, Jingjing; Kipping, David

    2017-01-01

    Forecaster predicts the mass (or radius) from the radius (or mass) for objects covering nine orders-of-magnitude in mass. It is an unbiased forecasting model built upon a probabilistic mass-radius relation conditioned on a sample of 316 well-constrained objects. It accounts for observational errors, hyper-parameter uncertainties and the intrinsic dispersions observed in the calibration sample.

  17. Exploring the Relationship Between Planet Mass and Atmospheric Metallicity for Cool Giant Planets

    NASA Astrophysics Data System (ADS)

    Thomas, Nancy H.; Wong, Ian; Knutson, Heather; Deming, Drake; Desert, Jean-Michel; Fortney, Jonathan J.; Morley, Caroline; Kammer, Joshua A.; Line, Michael R.

    2016-10-01

    Measurements of the average densities of exoplanets have begun to help constrain their bulk compositions and to provide insight into their formation locations and accretionary histories. Current mass and radius measurements suggest an inverse relationship between a planet's bulk metallicity and its mass, a relationship also seen in the gas and ice giant planets of our own solar system. We expect atmospheric metallicity to similarly increase with decreasing planet mass, but there are currently few constraints on the atmospheric metallicities of extrasolar giant planets. For hydrogen-dominated atmospheres, equilibrium chemistry models predict a transition from CO to CH4 below ~1200 K. However, with increased atmospheric metallicity the relative abundance of CH4 is depleted and CO is enhanced. In this study we present new secondary eclipse observations of a set of cool (<1200 K) giant exoplanets at 3.6 and 4.5 microns using the Spitzer Space Telescope, which allow us to constrain their relative abundances of CH4 and CO and corresponding atmospheric metallicities. We discuss the implications of our results for the proposed correlation between planet mass and atmospheric metallicity as predicted by the core accretion models and observed in our solar system.

  18. An Earth-mass planet orbiting α Centauri B.

    PubMed

    Dumusque, Xavier; Pepe, Francesco; Lovis, Christophe; Ségransan, Damien; Sahlmann, Johannes; Benz, Willy; Bouchy, François; Mayor, Michel; Queloz, Didier; Santos, Nuno; Udry, Stéphane

    2012-11-08

    Exoplanets down to the size of Earth have been found, but not in the habitable zone--that is, at a distance from the parent star at which water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for reasons such as tidal locking and strong stellar activity, they are unlikely to harbour water-carbon life as we know it. The detection of a habitable Earth-mass planet orbiting a star similar to our Sun is extremely difficult, because such a signal is overwhelmed by stellar perturbations. Here we report the detection of an Earth-mass planet orbiting our neighbour star α Centauri B, a member of the closest stellar system to the Sun. The planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star (one astronomical unit is the Earth-Sun distance).

  19. Search for earth mass planets and dark matter too

    SciTech Connect

    Rhie, S.H.; Bennett, D.P.

    1996-02-01

    Gravitational microlensing is known for baryonic dark matter searches. Here we show that microlensing also provides a unique tool for the detection of low mass planets (such as earths and neptunes) from the ground. A planetary system forms a binary lens (or, a multi-point lens), and we can determine the mass ratio of the planet with respect to the star and relative distance (= separation/Einstein ring radius) between the star and planet. Such a microlensing planet search project requires a {approx} 2 m survey telescope, and a network of 1.5 - 2 m follow-up telescopes capable of monitoring stars in the Bulge on a 24-hour basis. During the off-season of the Galactic bulge, this network can be used for dark matter search by monitoring the stars in the LMC and SMC.

  20. Debris Disk Structures Induced by Terrestrial-Mass Planets

    NASA Astrophysics Data System (ADS)

    Stark, C.; Kuchner, M. J.

    2007-06-01

    Three-body models of dust dynamics suggest that extrasolar planets can create significant resonant structures in exozodiacal clouds and other debris disks. These structures are a worrisome source of confusion for missions that aim to directly detect extrasolar planets. So far, most models of these resonant structures have focused on Neptune- and Jupiter-mass planets. However, our simulations suggest that, under the right conditions, terrestrial-mass planets can also create high-contrast structures. Using a custom tailored hybrid symplectic integrator on the 420-node Thunderhead cluster at Goddard Space Flight Center, we have performed many simulations of 25,000 particles each in an effort to catalog these structures. The models incorporate a realistic size distribution of particles and include enough particles to overcome the limitations of previous simulations that were often dominated by a handful of long-lived particles. These high-fidelity simulations allow us to confidently predict the contrast in the resulting ring structures.

  1. Debris Disk Structures Induced by Terrestrial-Mass Planets

    NASA Astrophysics Data System (ADS)

    Stark, Christopher C.; Kuchner, M. J.

    2007-07-01

    Three-body models of dust dynamics suggest that extrasolar planets can create significant resonant structures in exozodiacal clouds and other debris disks. These structures are a worrisome source of confusion for missions that aim to directly detect extrasolar planets. So far, most models of these resonant structures have focused on Neptune- and Jupiter-mass planets. However, our simulations suggest that, under the right conditions, terrestrial-mass planets can also create high-contrast structures. Using a custom tailored hybrid symplectic integrator on the 420-node Thunderhead cluster at Goddard Space Flight Center, we have performed many simulations of 25,000 particles each in an effort to catalog these structures. The models incorporate a realistic size distribution of particles and include enough particles to overcome the limitations of previous simulations that were often dominated by a handful of long-lived particles. These high-fidelity simulations allow us to confidently predict the contrast in the resulting ring structures.

  2. Terrestrial planets and water delivery around low-mass stars

    NASA Astrophysics Data System (ADS)

    Dugaro, A.; de Elía, G. C.; Brunini, A.; Guilera, O. M.

    2016-11-01

    Context. Theoretical and observational studies suggest that protoplanetary disks with a wide range of masses could be found around low-mass stars. Aims: We analyze planetary formation processes in systems without gas giants around M3- and M0-type stars of 0.29 M⊙ and 0.5 M⊙, respectively. In particular, we assume disks with masses of 5% and 10% of the mass of the star. Our study focuses on the formation of terrestrial-like planets and water delivery in the habitable zone (HZ). Methods: First, we use a semi-analytical model to describe the evolution of embryos and planetesimals during the gaseous phase. Then, a N-body code is used to analyze the last giant impact phase after the gas dissipation. Results: For M3-type stars, five planets with different properties are formed in the HZ. These planets have masses of 0.072 M⊕, 0.13 M⊕ (two of them), and 1.03 M⊕, and have water contents of 5.9%, 16.7%, 28.6%, and 60.6% by mass, respectively. Then, the fifth planet formed in the HZ is a dry world with 0.138 M⊕. For M0-type stars, four planets are produced in the HZ with masses of 0.28 M⊕, 0.51 M⊕, 0.72 M⊕, and 1.42 M⊕, and they have water contents of 26.7%, 45.8%, 68%, and 50.5% by mass, respectively. Conclusions: M3- and M0-type stars represent targets of interest for the search of exoplanets in the HZ. In fact, the Mars-mass planets formed around M3-type stars could maintain habitable conditions in their early histories. Thus, the search for candidates around young M3-type stars could lead to the detection of planets analogous to early Mars. Moreover, Earth-mass planets should also be discovered around M3-type stars and, sub- and super-Earths should be detected around M0-type stars. Such planets are very interesting since they could maintain habitable conditions for very long.

  3. A Venus-mass Planet Orbiting a Brown Dwarf: A Missing Link between Planets and Moons

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Jung, Y. K.; Han, C.; Gould, A.; Kozłowski, S.; Skowron, J.; Poleski, R.; Soszyński, I.; Pietrukowicz, P.; Mróz, P.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrzyński, G.; Shvartzvald, Y.; Maoz, D.; Kaspi, S.; Gaudi, B. S.; Hwang, K.-H.; Choi, J.-Y.; Shin, I.-G.; Park, H.; Bozza, V.

    2015-10-01

    The co-planarity of solar system planets led Kant to suggest that they formed from an accretion disk, and the discovery of hundreds of such disks around young stars as well as hundreds of co-planar planetary systems by the Kepler satellite demonstrate that this formation mechanism is extremely widespread. Many moons in the solar system, such as the Galilean moons of Jupiter, also formed out of the accretion disks that coalesced into the giant planets. Here we report the discovery of an intermediate system, OGLE-2013-BLG-0723LB/Bb, composed of a Venus-mass planet orbiting a brown dwarf, which may be viewed either as a scaled-down version of a planet plus a star or as a scaled-up version of a moon plus a planet orbiting a star. The latter analogy can be further extended since they orbit in the potential of a larger, stellar body. For ice-rock companions formed in the outer parts of accretion disks, like Uranus and Callisto, the scaled masses and separations of the three types of systems are similar, leading us to suggest that the formation processes of companions within accretion disks around stars, brown dwarfs, and planets are similar.

  4. What is the Mass of a Gap-opening Planet?

    NASA Astrophysics Data System (ADS)

    Dong, Ruobing; Fung, Jeffrey

    2017-02-01

    High-contrast imaging instruments such as GPI and SPHERE are discovering gap structures in protoplanetary disks at an ever faster pace. Some of these gaps may be opened by planets forming in the disks. In order to constrain planet formation models using disk observations, it is crucial to find a robust way to quantitatively back out the properties of the gap-opening planets, in particular their masses, from the observed gap properties, such as their depths and widths. Combining 2D and 3D hydrodynamics simulations with 3D radiative transfer simulations, we investigate the morphology of planet-opened gaps in near-infrared scattered-light images. Quantitatively, we obtain correlations that directly link intrinsic gap depths and widths in the gas surface density to observed depths and widths in images of disks at modest inclinations under finite angular resolution. Subsequently, the properties of the surface density gaps enable us to derive the disk scale height at the location of the gap h, and to constrain the quantity Mp2/α, where Mp is the mass of the gap-opening planet and α characterizes the viscosity in the gap. As examples, we examine the gaps recently imaged by VLT/SPHERE, Gemini/GPI, and Subaru/HiCIAO in HD 97048, TW Hya, HD 169142, LkCa 15, and RX J1615.3-3255. Scale heights of the disks and possible masses of the gap-opening planets are derived assuming each gap is opened by a single planet. Assuming α = 10‑3, the derived planet masses in all cases are roughly between 0.1 and 1 MJ.

  5. Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

    NASA Astrophysics Data System (ADS)

    Barnes, J. R.; Jenkins, J. S.; Jones, H. R. A.; Rojo, P.; Arriagada, P.; Jordán, A.; Minniti, D.; Tuomi, M.; Jeffers, S. V.; Pinfield, D.

    2013-04-01

    We present radial velocity results from our Red Optical Planet Survey (ROPS), aimed at detecting low-mass planets orbiting mid-late M dwarfs. The ˜10 ms-1 precision achieved over 2 consecutive nights with the MIKE spectrograph at Magellan Clay is also found on week long timescales with UVES at VLT. Since we find that UVES is expected to attain photon limited precision of order 2 ms-1 using our novel deconvolution technique, we are limited only by the (≤10 ms-1) stability of atmospheric lines. Rocky planet frequencies of η⊕ = 0.3-0.7 lead us to expect high planet yields, enabling determination of η⊕ for the uncharted mid-late M dwarfs with modest surveys.

  6. 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.

  7. 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.

  8. On the Minimum Core Mass for Giant Planet Formation

    NASA Astrophysics Data System (ADS)

    Piso, Ana-Maria; Youdin, Andrew; Murray-Clay, Ruth

    2013-07-01

    The core accretion model proposes that giant planets form by the accretion of gas onto a solid protoplanetary core. Previous studies have found that there exists a "critical core mass" past which hydrostatic solutions can no longer be found and unstable atmosphere collapse occurs. This core mass is typically quoted to be around 10Me. In standard calculations of the critical core mass, planetesimal accretion deposits enough heat to alter the luminosity of the atmosphere, increasing the core mass required for the atmosphere to collapse. In this study we consider the limiting case in which planetesimal accretion is negligible and Kelvin-Helmholtz contraction dominates the luminosity evolution of the planet. We develop a two-layer atmosphere model with an inner convective region and an outer radiative zone that matches onto the protoplanetary disk, and we determine the minimum core mass for a giant planet to form within the typical disk lifetime for a variety of disk conditions. We denote this mass as critical core mass. The absolute minimum core mass required to nucleate atmosphere collapse is ˜ 8Me at 5 AU and steadily decreases to ˜ 3.5Me at 100 AU, for an ideal diatomic gas with a solar composition and a standard ISM opacity law. Lower opacity and disk temperature significantly reduce the critical core mass, while a decrease in the mean molecular weight of the nebular gas results in a larger critical core mass. Our results yield lower mass cores than corresponding studies for large planetesimal accretion rates.

  9. A Large Hubble Space Telescope Survey of Low-Mass Exoplanets

    NASA Astrophysics Data System (ADS)

    Benneke, Björn; Crossfield, Ian; Knutson, Heather; Lothringer, Joshua; Dragomir, Diana; Fortney, Jonathan J.; Howard, Andrew; McCullough, Peter R.; Kempton, Eliza; Morley, Caroline

    2016-06-01

    The discovery of short-period planets with masses and radii between Earth and Neptune was one of the biggest surprises in the brief history of exoplanet science. From the Kepler mission, we now know that these “super-Earths” or "sub-Neptunes" orbit at least 40% of stars, likely representing the most common outcome of planet formation. Despite this ubiquity, we know little about their typical compositions and formation histories. Spectroscopic transit observations combined with powerful atmospheric retrieval tools can shed new light on these mysterious worlds. In this talk, we will present the main results from our 124-orbit Hubble Space Telescope survey to reveal the chemical diversity and formation histories of super-Earths. This unprecedented HST survey provides the first comprehensive look at this intriguing new class of planets ranging from 1 Neptune mass and temperatures close to 2000K to a 1 Earth mass planet near the habitable zone of its host star.

  10. Terrestrial planets in high-mass disks without gas giants

    NASA Astrophysics Data System (ADS)

    de Elía, G. C.; Guilera, O. M.; Brunini, A.

    2013-09-01

    Context. Observational and theoretical studies suggest that planetary systems consisting only of rocky planets are probably the most common in the Universe. Aims: We study the potential habitability of planets formed in high-mass disks without gas giants around solar-type stars. These systems are interesting because they are likely to harbor super-Earths or Neptune-mass planets on wide orbits, which one should be able to detect with the microlensing technique. Methods: First, a semi-analytical model was used to define the mass of the protoplanetary disks that produce Earth-like planets, super-Earths, or mini-Neptunes, but not gas giants. Using mean values for the parameters that describe a disk and its evolution, we infer that disks with masses lower than 0.15 M⊙ are unable to form gas giants. Then, that semi-analytical model was used to describe the evolution of embryos and planetesimals during the gaseous phase for a given disk. Thus, initial conditions were obtained to perform N-body simulations of planetary accretion. We studied disks of 0.1, 0.125, and 0.15 M⊙. Results: All our simulations form massive planets on wide orbits. For a 0.1 M⊙ disk, 2-3 super-Earths of 2.8 to 5.9 M⊕ are formed between 2 and 5 AU. For disks of 0.125 and 0.15 M⊙, our simulations produce a 10-17.1 M⊕ planet between 1.6 and 2.7 AU, and other super-Earths are formed in outer regions. Moreover, six planets survive in the habitable zone (HZ). These planets have masses from 1.9 to 4.7 M⊕ and significant water contents ranging from 560 to 7482 Earth oceans, where one Earth ocean represents the amount of water on Earth's surface, which equals 2.8 × 10-4M⊕. Of the six planets formed in the HZ, three are water worlds with 39%-44% water by mass. These planets start the simulations beyond the snow line, which explains their high water abundances. In general terms, the smaller the mass of the planets observed on wide orbits, the higher the possibility to find water worlds in the

  11. 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.

  12. Masses, Radii, and Cloud Properties of the HR 8799 Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard

    2012-01-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have compared the photometric and limited spectral data of the planets to the predictions of various atmosphere and evolution models and concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Most studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against field L and T dwarfs, including the reddest L dwarfs. Unlike almost all previous studies we specify mutually self-consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure yields plausible and self-consistent values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are in fact not unusual but rather follow previously recognized trends including a gravity dependence on the temperature of the L to T spectral transition, some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to the H and K band spectrum. Solutions for planets c and particularly d are less certain but are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that as for L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present a new evolution calculation that predicts cooling tracks on the near-infrared color

  13. Revised Masses and Densities of the Planets around Kepler-10

    NASA Astrophysics Data System (ADS)

    Weiss, Lauren M.; Rogers, Leslie A.; Isaacson, Howard T.; Agol, Eric; Marcy, Geoffrey W.; Rowe, Jason F.; Kipping, David; Fulton, Benjamin J.; Lissauer, Jack J.; Howard, Andrew W.; Fabrycky, Daniel

    2016-03-01

    Determining which small exoplanets have stony-iron compositions is necessary for quantifying the occurrence of such planets and for understanding the physics of planet formation. Kepler-10 hosts the stony-iron world Kepler-10b, and also contains what has been reported to be the largest solid silicate-ice planet, Kepler-10c. Using 220 radial velocities (RVs), including 72 precise RVs from Keck-HIRES of which 20 are new from 2014 to 2015, and 17 quarters of Kepler photometry, we obtain the most complete picture of the Kepler-10 system to date. We find that Kepler-10b ({R}{{p}}=1.47 {R}\\oplus ) has mass 3.72\\quad +/- \\quad 0.42\\quad {M}\\oplus and density 6.46\\quad +/- \\quad 0.73\\quad {{g}} {{cm}}-3. Modeling the interior of Kepler-10b as an iron core overlaid with a silicate mantle, we find that the iron core constitutes 0.17 ± 0.11 of the planet mass. For Kepler-10c ({R}{{p}}=2.35 {R}\\oplus ) we measure mass 13.98\\quad +/- \\quad 1.79\\quad {M}\\oplus and density 5.94\\quad +/- \\quad 0.76\\quad {{g}} {{cm}}-3, significantly lower than the mass computed in Dumusque et al. (17.2+/- 1.9 {M}\\oplus ). Our mass measurement of Kepler-10c rules out a pure stony-iron composition. Internal compositional modeling reveals that at least 10% of the radius of Kepler-10c is a volatile envelope composed of hydrogen-helium (0.2% of the mass, 16% of the radius) or super-ionic water (28% of the mass, 29% of the radius). However, we note that analysis of only HIRES data yields a higher mass for planet b and a lower mass for planet c than does analysis of the HARPS-N data alone, with the mass estimates for Kepler-10 c being formally inconsistent at the 3σ level. Moreover, dividing the data for each instrument into two parts also leads to somewhat inconsistent measurements for the mass of planet c derived from each observatory. Together, this suggests that time-correlated noise is present and that the uncertainties in the masses of the planets (especially planet c) likely

  14. DISCOVERY AND MASS MEASUREMENTS OF A COLD, 10 EARTH MASS PLANET AND ITS HOST STAR

    SciTech Connect

    Muraki, Y.; Han, C.; Bennett, D. P.; Suzuki, D.; Sumi, T.; Monard, L. A. G.; Street, R.; Jorgensen, U. G.; Kundurthy, P.; Becker, A. C.; Skowron, J.; Gaudi, B. S.; Albrow, M. D.; Fouque, P.; Heyrovsky, D.; Barry, R. K.; Beaulieu, J.-P.; Wellnitz, D. D.; Bond, I. A.; Dong, S. E-mail: bennett@nd.edu

    2011-11-01

    We present the discovery and mass measurement of the cold, low-mass planet MOA-2009-BLG-266Lb, performed with the gravitational microlensing method. This planet has a mass of m{sub p} = 10.4 {+-} 1.7 M{sub +} and orbits a star of mass M{sub *} = 0.56 {+-} 0.09 M{sub sun} at a semimajor axis of a = 3.2{sub -0.5}{sup +1.9} AU and an orbital period of P = 7.6{sub -1.5}{sup +7+7} yrs. The planet and host star mass measurements are enabled by the measurement of the microlensing parallax effect, which is seen primarily in the light curve distortion due to the orbital motion of the Earth. But the analysis also demonstrates the capability to measure the microlensing parallax with the Deep Impact (or EPOXI) spacecraft in a heliocentric orbit. The planet mass and orbital distance are similar to predictions for the critical core mass needed to accrete a substantial gaseous envelope, and thus may indicate that this planet is a 'failed' gas giant. This and future microlensing detections will test planet formation theory predictions regarding the prevalence and masses of such planets.

  15. Evolution of Giant Planets Close to the Roche Limit

    NASA Astrophysics Data System (ADS)

    Valsecchi, Francesca

    2015-12-01

    Two formation models have been proposed to explain hot Jupiters’ tight orbits. These could have migrated inward in a disk (disk migration), or they could have formed via tidal circularization of an orbit made highly eccentric following gravitational interactions with a companion (high-eccentricity migration). I will show how current observations coupled with a detailed treatment of tides can be used to constrain both hot Jupiter formation and tidal dissipation theories.Eventually, stellar tides will cause the orbits of many hot Jupiters to decay down to their Roche limit. Using a detailed binary mass transfer model we show how a hot Jupiter undergoing a phase of Roche-lobe overflow (RLO) leads to lower-mass planets in orbits of a few days. The remnant planets have a rocky core and some amount of envelope material, which is slowly removed via photo-evaporation at nearly constant orbital period; these have properties resembling many of the observed super-Earths and sub-Neptunes. For these remnant planets we also predict an anti-correlation between mass and orbital period; very low-mass planets in ultra-short periods cannot be produced through this type of evolution.

  16. 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.

  17. Discovery and Mass Measurements of a Cold, 10-Earth Mass Planet and Its Host Star

    NASA Technical Reports Server (NTRS)

    Barry, Richard K.; Muraki, Y.; Han, C.; Bennett, D. P.; Gaudi, B. S.

    2011-01-01

    We present the discovery and mass measurement of the cold, low-mass planet MOA-2009-BLG-266Lb, made with the gravitational microlensing method. This planet has a mass of mp = 10.4 +/- M(Earth) and orbits a star of Mstar = 0.56 +/- 0.09 M(Sun) at a semi-major axis of a = 3.2 + 1.9/-0.5 AU, and an orbital period of 7.6 +7.7/-1.5 yrs. The planet and host star mass measurements are due to the measurement of the microlensing parallax effect. This measurement was primarily due to the orbital motion of the Earth, but the analysis also demonstrates the capability measure micro lensing parallax with the Deep Impact (or EPOXI) spacecraft in a Heliocentric orbit. The planet mass and orbital distance are similar to predictions for the critical core mass needed to accrete a substantial gaseous envelope, and thus may indicate that this planet is a failed gas giant. This and future microlensing detections will test planet formation theory predictions regarding the prevalence and masses of such planets

  18. Observational constraints on planet formation and migration timescales

    NASA Astrophysics Data System (ADS)

    David, Trevor J.

    2017-01-01

    Short-period planets have the power to unlock many of the mysteries of planet formation and, fortunately, they are abundant. There is growing evidence that high-eccentricity migration channels are not responsible for all short-period planets; this notion is supported by the recent discovery of K2-33 b, a short-period, Neptune-sized exoplanet transiting a 5-10 Myr old star in the Upper Scorpius association. While in situ formation of K2-33 b can not be conclusively ruled out, the planet is parked just interior to the corotation radius, where theory predicts inwardly migrating planets are halted; this may be interpreted as tantalizing evidence of disk-driven migration. Occurrence rate studies of all clusters observed by K2 will allow for robust conclusions about the predominant modes of planet migration. Moreover, K2-33 b is likely still contracting, and should eventually join the populous class of close-in sub-Neptunes. In addition to K2-33 b, the Kepler/K2 mission has enabled the discovery of planets in the intermediate age Hyades and Praesepe clusters. Many of these close-in planets exhibit radii that are large given their semi-major axes and host star characteristics. It is possible that, even at ages of several hundred Myr, these planets have not finished contracting or are undergoing atmospheric mass loss. If this is the case, we are directly constraining the evolutionary timescales of short-period planets. Finally, the characteristic timescales of protoplanetary disk evolution (and thus giant planet formation) and debris disk evolution can be refined with new fundamental calibrators for pre-main sequence evolutionary models and modern catalogs of homogeneous stellar ages, respectively.

  19. 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.

  20. MEASURING THE MASS OF SOLAR SYSTEM PLANETS USING PULSAR TIMING

    SciTech Connect

    Champion, D. J.; Hobbs, G. B.; Manchester, R. N.; Edwards, R. T.; Burke-Spolaor, S.; Sarkissian, J. M.; Backer, D. C.; Bailes, M.; Bhat, N. D. R.; Van Straten, W.; Coles, W.; Demorest, P. B.; Ferdman, R. D.; Purver, M. B.; Folkner, W. M.; Hotan, A. W.; Kramer, M.; Lommen, A. N.; Nice, D. J.; Stairs, I. H.

    2010-09-10

    High-precision pulsar timing relies on a solar system ephemeris in order to convert times of arrival (TOAs) of pulses measured at an observatory to the solar system barycenter. Any error in the conversion to the barycentric TOAs leads to a systematic variation in the observed timing residuals; specifically, an incorrect planetary mass leads to a predominantly sinusoidal variation having a period and phase associated with the planet's orbital motion about the Sun. By using an array of pulsars (PSRs J0437-4715, J1744-1134, J1857+0943, J1909-3744), the masses of the planetary systems from Mercury to Saturn have been determined. These masses are consistent with the best-known masses determined by spacecraft observations, with the mass of the Jovian system, 9.547921(2) x10{sup -4} M {sub sun}, being significantly more accurate than the mass determined from the Pioneer and Voyager spacecraft, and consistent with but less accurate than the value from the Galileo spacecraft. While spacecraft are likely to produce the most accurate measurements for individual solar system bodies, the pulsar technique is sensitive to planetary system masses and has the potential to provide the most accurate values of these masses for some planets.

  1. 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.

  2. Periodic mass extinctions and the Planet X model reconsidered

    NASA Astrophysics Data System (ADS)

    Whitmire, Daniel P.

    2016-01-01

    The 27 Myr period in the fossil extinction record has been confirmed in modern data bases dating back 500 Myr, which is twice the time interval of the original analysis from 30 years ago. The surprising regularity of this period has been used to reject the Nemesis model. A second model based on the Sun's vertical Galactic oscillations has been challenged on the basis of an inconsistency in period and phasing. The third astronomical model originally proposed to explain the periodicity is the Planet X model in which the period is associated with the perihelion precession of the inclined orbit of a trans-Neptunian planet. Recently, and unrelated to mass extinctions, a trans-Neptunian super-Earth planet has been proposed to explain the observation that the inner Oort cloud objects Sedna and 2012VP113 have perihelia that lie near the ecliptic plane. In this Letter, we reconsider the Planet X model in light of the confluence of the modern palaeontological and outer Solar system dynamical evidence.

  3. 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.

  4. Occurrence rate of low-mass planets around nearby M dwarfs

    NASA Astrophysics Data System (ADS)

    Jones, Hugh

    2015-08-01

    We re-analyse archival radial velocities of nearby M dwarfs to constrain low-amplitude Keplerian signals. We apply a variety of signal detection criteria and photometric monitoring to assess the number of planet candidates in the sample. We use the estimated detection probability function to calculate the occurrence rate of low-mass planets around nearby M dwarfs. Our results indicate that M dwarfs are hosts to an abundance of low-mass planets and the occurrence rate of planets less massive than 10 Earth masses is of the order of one planet per star and that planets are common in the stellar habitable zones of M dwarfs.

  5. Effects of mass loss for highly-irradiated giant planets

    NASA Astrophysics Data System (ADS)

    Hubbard, W. B.; Hattori, M. F.; Burrows, A.; Hubeny, I.; Sudarsky, D.

    2007-04-01

    We present calculations for the evolution and surviving mass of highly-irradiated extrasolar giant planets (EGPs) at orbital semimajor axes ranging from 0.023 to 0.057 AU using a generalized scaled theory for mass loss, together with new surface-condition grids for hot EGPs and a consistent treatment of tidal truncation. Theoretical estimates for the rate of energy-limited hydrogen escape from giant-planet atmospheres differ by two orders of magnitude, when one holds planetary mass, composition, and irradiation constant. Baraffe et al. [Baraffe, I., Selsis, F., Chabrier, G., Barman, T.S., Allard, F., Hauschildt, P.H., Lammer, H., 2004. Astron. Astrophys. 419, L13-L16] predict the highest rate, based on the theory of Lammer et al. [Lammer, H., Selsis, F., Ribas, I., Guinan, E.F., Bauer, S.J., Weiss, W.W., 2003. Astrophys. J. 598, L121-L124]. Scaling the theory of Watson et al. [Watson, A.J., Donahue, T.M., Walker, J.C.G., 1981. Icarus 48, 150-166] to parameters for a highly-irradiated exoplanet, we find an escape rate ˜10 lower than Baraffe's. With the scaled Watson theory we find modest mass loss, occurring early in the history of a hot EGP. In this theory, mass loss including the effect of Roche-lobe overflow becomes significant primarily for masses below a Saturn mass, for semimajor axes ⩾0.023 AU. This contrasts with the Baraffe model, where hot EGPs are claimed to be remnants of much more massive bodies, originally several times Jupiter and still losing substantial mass fractions at present.

  6. Mass-Radius Relation for Rocky Planets Based on PREM

    NASA Astrophysics Data System (ADS)

    Zeng, Li; Sasselov, Dimitar D.; Jacobsen, Stein B.

    2016-03-01

    Several small dense exoplanets are now known, inviting comparisons to Earth and Venus. Such comparisons require translating their masses and sizes to composition models of evolved multi-layer interior planets. Such theoretical models rely on our understanding of the Earth’s interior, as well as independently derived equations of state, but so far have not involved direct extrapolations from Earth’s seismic model: the Preliminary Reference Earth Model (PREM). To facilitate more detailed compositional comparisons between small exoplanets and the Earth, we derive here a semi-empirical mass-radius relation for two-layer rocky planets based on PREM, \\frac{R}{{R}\\oplus }=(1.07-0.21\\cdot {CMF})\\cdot {≤ft(\\frac{M}{{M}\\oplus }\\right)}1/3.7, where CMF stands for core mass fraction. It is applicable to 1 ˜ 8 M⊕ and a CMF of 0.0 ˜ 0.4. Applying this formula to Earth and Venus and several known small exoplanets with radii and masses measured to better than ˜30% precision gives a CMF fit of 0.26 ± 0.07.

  7. Constraining the Masses of the Kepler-11 Planets through Radial Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Weiss, Lauren M.; Marcy, Geoffrey W.; Isaacson, Howard T.

    2015-01-01

    The six transiting planets of Kepler-11 have all been found to have ultra-low densities through N-body dynamical analysis of the transit timing variations (TTVs) of the six planets. Numerically reproducing TTVs has become a new method for solving the masses of planets, but this method is susceptible to certain dynamic degeneracies: the planet eccentricity is degenerate with the planet mass, and perturbations caused by non-transiting planets could be misattributed to the transiting planets. Furthermore, the masses of planets characterized by TTV analysis are systematically 2x lower than the masses (including non-detections) reported by radial velocity (RV) analysis for planets of the same radius. We address the discrepancy between the TTV- and RV-determined planet masses by measuring the RVs of Kepler-11 at opportunistic times, as determined by the ephemerides of the transiting planets. We place an upper limit on the masses of the Kepler-11 planets using RVs and preliminarily show that the RVs are consistent with the ultra-low mass scenario determined by the TTVs. The lack of disagreement between the TTVs and RVs in the Kepler-11 system bodes well for N-body simulations of TTVs for other Kepler systems that are too faint for RV follow-up.

  8. Aeronomical constraints to the minimum mass and maximum radius of hot low-mass planets

    NASA Astrophysics Data System (ADS)

    Fossati, L.; Erkaev, N. V.; Lammer, H.; Cubillos, P. E.; Odert, P.; Juvan, I.; Kislyakova, K. G.; Lendl, M.; Kubyshkina, D.; Bauer, S. J.

    2017-02-01

    Stimulated by the discovery of a number of close-in low-density planets, we generalise the Jeans escape parameter taking hydrodynamic and Roche lobe effects into account. We furthermore define Λ as the value of the Jeans escape parameter calculated at the observed planetary radius and mass for the planet's equilibrium temperature and considering atomic hydrogen, independently of the atmospheric temperature profile. We consider 5 and 10 M⊕ planets with an equilibrium temperature of 500 and 1000 K, orbiting early G-, K-, and M-type stars. Assuming a clear atmosphere and by comparing escape rates obtained from the energy-limited formula, which only accounts for the heating induced by the absorption of the high-energy stellar radiation, and from a hydrodynamic atmosphere code, which also accounts for the bolometric heating, we find that planets whose Λ is smaller than 15-35 lie in the "boil-off" regime, where the escape is driven by the atmospheric thermal energy and low planetary gravity. We find that the atmosphere of hot (i.e. Teq ⪆ 1000 K) low-mass (Mpl ⪅ 5 M⊕) planets with Λ< 15-35 shrinks to smaller radii so that their Λ evolves to values higher than 15-35, hence out of the boil-off regime, in less than ≈500 Myr. Because of their small Roche lobe radius, we find the same result also for hot (i.e. Teq⪆ 1000 K) higher mass (Mpl ⪅ 10 M⊕) planets with Λ< 15-35, when they orbit M-dwarfs. For old, hydrogen-dominated planets in this range of parameters, Λ should therefore be ≥15-35, which provides a strong constraint on the planetary minimum mass and maximum radius and can be used to predict the presence of aerosols and/or constrain planetary masses, for example.

  9. Theory of giant planet atmospheres and spectra

    NASA Astrophysics Data System (ADS)

    Burrows, Adam Seth

    2014-06-01

    Giant exoplanet atmospheres have now been studied by transit spectroscopy, spectroscopy and photometry at secondary eclipse, photometric light curves as a function of orbital phase, very high-resolution spectroscopic velocity measurements, and high-contrast imaging. Moreover, there is a correspondence between brown dwarf and giant planet atmospheres and spectra that has been profitably exploited for many years to better understand exoplanets. In this presentation, I endeavor to review the information extracted by these techniques about close-in giant exoplanet compositions and temperatures. Then, I will summarize the expected character of the spectra, light curves, and polarizations of the objects soon to be studied using high-contrast imaging by GPI, SPHERE, WFIRST-AFTA, and Subaru/HiCIAO as a function of mass, age, Keplerian elements, and birth properties (such as entropy). The goal will be to frame the theoretical discussion concerning what physical information can be gleaned in the next years about giant planet atmospheres by direct (or almost direct) imaging and characterization campaigns, and their role as stepping stones to the even more numerous sub-Neptunes, super-Earths, and Earths.

  10. Towards a Comprehensive Set of Atmosphere and Evolution Models from Brown Dwarfs, to Gas Giants, to Sub-Neptunes

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Marley, Mark; Morley, Caroline; Visscher, Channon; Lupu, Roxana; Freedman, Richard

    2015-12-01

    High signal-to-noise spectral observations of the thermal emission of brown dwarfs have been routinely achieved for 20 years, and for extrasolar gas giant planets for nearly 10 years. JWST may allow for the detection of emission for exo-Neptune-class planets at large orbital separations. Given these large and growing databases of spectra, there is a need for a large suite of state-of-the-art models for comparison with these data. These H/He dominated atmospheres span a range of nearly 2000 in mass and perhaps a similar range in atmospheric metallicity. In addition, for all of these classes of planets, the radiative-convective atmosphere serves as a bottleneck for interior cooling, so an understanding of the atmosphere is essential to understand thermal evolution. Here we present our initial plans for a large grid of atmosphere models, over a range of Teff from 200 K to 2400 K, log g from 2.5 to 5.5, metallicities from 0.1 to 300X solar, across a range of cloud parametrizations, vertical mixing efficiencies, and C/O ratios. For brown dwarfs and for metal-enriched giant planets, these atmospheres will be coupled to thermal evolution in a self-consistent manner. Here we present some initial calculations for the atmospheric structure and emitted spectra for the metal-enriched "planetary" portion of the grid, from 10X to 300X solar.

  11. Extrasolar planet population synthesis . IV. Correlations with disk metallicity, mass, and lifetime

    NASA Astrophysics Data System (ADS)

    Mordasini, C.; Alibert, Y.; Benz, W.; Klahr, H.; Henning, T.

    2012-05-01

    Context. This is the fourth paper in a series showing the results of planet population synthesis calculations. In Paper I, we presented our methods. In Paper II, we compared the synthetic and the observed planetary population statistically. Paper III addressed the influences of the stellar mass on the population. Aims: Our goal in this fourth paper is to systematically study the effects of important disk properties, namely disk metallicity, mass, and lifetime on fundamental properties of planets like mass and semimajor axis. Methods: For a large number of protoplanetary disks that have properties following distributions derived from observations, we calculated a population of planets with our formation model. The model is based on the classical core accretion paradigm but self-consistently includes planet migration and disk evolution. Results: We find a very large number of correlations. Regarding the planetary initial mass function, metallicity, Mdisk, and τdisk play different roles. For high metallicities, giant planets are more frequent. For high Mdisk, giant planets are more massive. For long τdisk, giant planets are both more frequent and massive. At low metallicities, very massive giant planets cannot form, but otherwise giant planet mass and metallicity are nearly uncorrelated. In contrast, (maximum) planet masses and disk gas masses are correlated. The formation of giant planets is possible for initial planetesimal surface densities ΣS of at least 6 g/cm2 at 5.2 AU. The best spot for giant planet formation is at ~5 AU. In- and outside this distance, higher ΣS are necessary. Low metallicities can be compensated for by high Mdisk, and vice versa, but not ad infinitum. At low metallicities, giant planets only form outside the ice line, while giant planet formation occurs throughout the disk at high metallicities. The extent of migration increases with Mdisk and τdisk and usually decreases with metallicity. No clear correlation of metallicity and the

  12. Identifying the upper atmosphere structure of the inflated hot sub-Neptune CoRoT-24b

    NASA Astrophysics Data System (ADS)

    Juvan, Ines; Lammer, Helmut; Erkaev, Nikolai V.; Fossati, Luca; Cubillos, Patricio E.; Guenther, Eike; Odert, Petra; Kislyakova, Kristina G.; Lendl, Monika

    2016-04-01

    The CoRoT satellite mission discovered two Neptune-type planets, CoRoT-24b and CoRoT-24c, with observed transit radii of ≈3.7REarth and ≈4.9REarth and masses of ≤5.7MEarth and ≈28MEarth, respectively. From the deduced low mean densities it can be expected that their planetary cores are most likely surrounded by H2 dominated envelopes. While having very similar radii, the outer planet CoRoT-24c is at least 4.9 times more massive than its neighbour, indicating that their atmospheres can be fundamentally different. Therefore, we have investigated the upper atmosphere structure and escape rates of these two planets. We applied a hydrodynamic upper atmosphere model including heating by absorption of stellar extreme ultraviolet and X-ray (XUV) radiation, under the assumption that the observed transit radius RT is produced by Rayleigh scattering and H2-H2 collision absorption in a pure hydrogen atmosphere. This corresponds to a pressure level near 1 bar. We find an unsustainably high hydrodynamic escape rate of 1.6 × 1011 g/s for the atmosphere of CoRoT-24b. If real, such high atmospheric escape would lead to substantial mass loss from the planetary atmosphere, shrinking it to ≈2.2REarth within ≈4 Myr, which is inconsistent with the old age of the system. The solution to this discrepancy is that the observed transit radius RT must be 30-60% larger than the actual planetary radius at the 1 bar pressure level. We suggest that the observed transit radius RT is produced by absorption through scattering processes due to high altitude clouds or hazes. The Kepler satellite has discovered similar close-in low-density Neptune-type planets. We propose that it is very likely that the observed transit radii for the vast majority of these planets also differ from their actual planetary radii at the 1 bar pressure level. This would introduce a systematic bias in the measured radii and has dramatic implications in the determination of the mass-radius relation and for planet

  13. Measuring the Radius and Mass of Planet Nine

    NASA Astrophysics Data System (ADS)

    Schneider, J.

    2017-10-01

    Batygin & Brown (2016) suggested the existence of a new planet in our solar system that is supposed to be responsible for the perturbation of eccentric orbits of small outer bodies. The main challenge now is to detect and characterize this putative body. Here, we investigate the principles of the determination of its physical parameters, mainly its mass and radius. For that purpose, we concentrate on two methods: stellar occultations and gravitational microlensing effects (amplification, deflection, and time delay). We estimate the main characteristics of a possible occultation or gravitational effects: flux variation of a background star, duration, and probability of occurrence. We also investigate the additional benefits of direct imaging and of an occultation.

  14. 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.

  15. A Multi-planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315

    NASA Astrophysics Data System (ADS)

    Rodriguez, Joseph E.; Zhou, George; Vanderburg, Andrew; Eastman, Jason D.; Kreidberg, Laura; Cargile, Phillip A.; Bieryla, Allyson; Latham, David W.; Irwin, Jonathan; Mayo, Andrew W.; Calkins, Michael L.; Esquerdo, Gilbert A.; Mink, Jessica

    2017-06-01

    We report the discovery of a multi-planet system orbiting HD 106315, a rapidly rotating mid F-type star, using data from the K2 mission. HD 106315 hosts a 2.51 ± 0.12 R ⊕ sub-Neptune in a 9.5-day orbit and a {4.31}-0.27+0.24 {R}\\oplus super-Neptune in a 21-day orbit. The projected rotational velocity of HD 106315 (12.9 km s-1) likely precludes precise measurements of the planets’ masses but could enable a measurement of the sky-projected spin-orbit obliquity for the outer planet via Doppler tomography. The eccentricities of both planets were constrained to be consistent with 0, following a global modeling of the system that includes a Gaia distance and dynamical arguments. The HD 106315 system is one of few multi-planet systems hosting a Neptune-sized planet for which orbital obliquity measurements are possible, making it an excellent test-case for formation mechanisms of warm-Neptunian systems. The brightness of the host star also makes HD 106315 c a candidate for future transmission spectroscopic follow-up studies.

  16. Atmospheres and Oceans of Rocky Planets In and Beyond the Habitable Zones of M dwarfs

    NASA Astrophysics Data System (ADS)

    Tian, Feng

    2015-12-01

    he evolution of M dwarfs during their pre-main-sequence phase causes rocky planets in and beyond the habitable zones these stars to be in the runaway and moist greenhouse states. This scenario has been studied by three groups of researchers recently (Ramirez and Kaltenegger 2014, Tian and Ida 2015, Luger and Barnes 2015), and their consensus is that massive amount of water could have been lost during this time -- early evolution of M dwarfs could have changed the water contents of rocky planets around them, which could strongly influence the habitability of rocky planets around low mass stars. It has been proposed that dense oxygen dominant atmospheres (up to 2000 bars, Luger and Barnes 2015) because of rapid water loss. Is this true? If so, what's the condition for such atmospheres to exist and can they be maintained? On the other hand, what's the likelihood for sub-Neptunes to shrink into habitable planets under such environment? In general how is the habitability of planets around M dwarfs different from those around Sun-type stars? These are the questions we will attempt to address in this work.

  17. STELLAR PARAMETERS AND METALLICITIES OF STARS HOSTING JOVIAN AND NEPTUNIAN MASS PLANETS: A POSSIBLE DEPENDENCE OF PLANETARY MASS ON METALLICITY

    SciTech Connect

    Ghezzi, L.; Cunha, K.; De Araujo, F. X.; De la Reza, R.; Smith, V. V.; Schuler, S. C.

    2010-09-10

    The metal content of planet-hosting stars is an important ingredient that may affect the formation and evolution of planetary systems. Accurate stellar abundances require the determinations of reliable physical parameters, namely, the effective temperature, surface gravity, microturbulent velocity, and metallicity. This work presents the homogeneous derivation of such parameters for a large sample of stars hosting planets (N = 117), as well as a control sample of disk stars not known to harbor giant, closely orbiting planets (N = 145). Stellar parameters and iron abundances are derived from an automated analysis technique developed for this work. As previously found in the literature, the results in this study indicate that the metallicity distribution of planet-hosting stars is more metal rich by {approx}0.15 dex when compared to the control sample stars. A segregation of the sample according to planet mass indicates that the metallicity distribution of stars hosting only Neptunian-mass planets (with no Jovian-mass planets) tends to be more metal poor in comparison with that obtained for stars hosting a closely orbiting Jovian planet. The significance of this difference in metallicity arises from a homogeneous analysis of samples of FGK dwarfs which do not include the cooler and more problematic M dwarfs. This result would indicate that there is a possible link between planet mass and metallicity such that metallicity plays a role in setting the mass of the most massive planet. Further confirmation, however, must await larger samples.

  18. Delay of planet formation at large radius and the outward decrease in mass and gas content of Jovian planets

    NASA Astrophysics Data System (ADS)

    Jin, Li-Ping; Liu, Chun-Jian; Zhang, Yu

    2015-09-01

    A prominent observation of the solar system is that the mass and gas content of Jovian planets decrease outward with orbital radius, except that, in terms of these properties, Neptune is almost the same as Uranus. In previous studies, the solar nebula was assumed to preexist and the formation process of the solar nebula was not considered. It was therefore assumed that planet formation at different radii started at the same time in the solar nebula. We show that planet formation at different radii does not start at the same time and is delayed at large radii. We suggest that this delay might be one of the factors that causes the outward decrease in the masses of Jovian planets. The nebula starts to form from its inner part because of the inside-out collapse of its progenitorial molecular cloud core. The nebula then expands outward due to viscosity. Material first reaches a small radius and then reaches a larger radius, so planet formation is delayed at the large radius. The later the material reaches a planet's location, the less time it has to gain mass and gas content. Hence, the delay tends to cause the outward decrease in mass and gas content of Jovian planets. Our nebula model shows that the material reaches Jupiter, Saturn, Uranus and Neptune at t = 0.40, 0.57, 1.50 and 6.29 × 106 yr, respectively. We discuss the effects of time delay on the masses of Jovian planets in the framework of the core accretion model of planet formation. Saturn's formation is not delayed by much time relative to Jupiter so that they both reach the rapid gas accretion phase and become gas giants. However, the delay in formation of Uranus and Neptune is long and might be one of the factors that cause them not to reach the rapid gas accretion phase before the gas nebula is dispersed. Saturn has less time to go through the rapid gas accretion, so Saturn's mass and gas content are significantly less than those of Jupiter.

  19. Pathways towards Neptune-mass Planets around Very Low-mass Stars

    NASA Astrophysics Data System (ADS)

    Dreizler, S.; Bean, J.; Seifahrt, A.; Hartman, H.; Nilsson, H.; Wiedemann, G.; Reiners, A.; Henry, T. J.

    2010-10-01

    Radial velocities measured from near-infrared spectra are a potentially powerful tool to search for planets around low-mass stars. The radial velocity precision routinely obtained in the visible can, however, not be achieved in the NIR with existing techniques. In this paper, we describe a method for measuring high-precision radial velocities of a sample of the lowest-mass M dwarfs using CRIRES on the VLT. Our project makes use of a gas cell filled with ammonia to calibrate the instrument response similar to the iodine cell technique that has been used so successfully in the visible. Tests of the method based on the analysis of hundreds of spectra obtained for late M dwarfs over six months demonstrate that precisions of ˜5 m s-1 are obtainable over long timescales, and precisions better than 3 m s-1 can be obtained over timescales up to a week. This allows to search for low-mass planets, i.e., Neptune-mass or even Super-Earth planets around very low-mass stars or sub-stellar objects.

  20. Precisely measuring the density of small transiting exoplanets with particular emphasis on longer period planet using the HARPS-N spectrograph

    NASA Astrophysics Data System (ADS)

    Buchhave, Lars A.

    2015-08-01

    The majority of exoplanets discovered by the Kepler Mission have sizes that range between 1-4 Earth radii, populating a regime of planets with no Solar System analogues. This regime is critical for understanding the frequency of potentially habitable worlds and to help inform planet formation theories, because it contains the transition from lower-density planets with extended H/He envelopes to higher-density rocky planets with compact atmospheres. HARPS-N is an ultra-stable high-resolution spectrograph optimized for the measurement of precise radial velocities, yielding precise planetary masses and thus densities of small transiting exoplanets. In this talk, I will review the progress to populate the mass-radius parameter space with precisely measured densities of small planets. I will in particular focus on the latest HARPS-N results and their implication for our understanding of these super-Earth and small Neptune type planets.Additionally, I will discuss our progress to measure the masses of longer period sub-Neptune sized planets. In Buchhave el al. 2014, we found suggestive observational evidence that the transition from rocky to gaseous planets might depend on the orbital period, such that larger planets further away from their host star could be massive planets without a large gaseous envelope. To test this hypothesis, we have used HARPS-N to observe longer period planet candidates to determine whether they are in fact massive rocky planets or if they have extended H/He envelopes and thus lower bulk densities.HARPS-N at the Telescopio Nazionale Galileo, La Palma is an international collaboration and was funded by the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, and the Italian National Astrophysical Institute, University of St. Andrews, Queens University Belfast, and University of Edinburgh.

  1. Investigating the free-floating planet mass by Euclid observations

    NASA Astrophysics Data System (ADS)

    Hamolli, Lindita; Hafizi, Mimoza; De Paolis, Francesco; Nucita, Achille A.

    2016-08-01

    The detection of anomalies in gravitational microlensing events is nowadays one of the main goals among the microlensing community. In the case of single-lens events, these anomalies can be caused by the finite source effects, that is when the source disk size is not negligible, and by the Earth rotation around the Sun (the so-called parallax effect). The finite source and parallax effects may help to define the mass of the lens, uniquely. Free-floating planets (FFPs) are extremely dim objects, and gravitational microlensing provides at present the exclusive method to investigate these bodies. In this work, making use of a synthetic population algorithm, we study the possibility of detecting the finite source and parallax effects in simulated microlensing events caused by FFPs towards the Galactic bulge, taking into consideration the capabilities of the space-based Euclid telescope. We find a significant efficiency for detecting the parallax effect in microlensing events with detectable finite source effect, that turns out to be about 51 % for mass function index α_{PL} = 1.3.

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

    PubMed

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

    2016-07-01

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

  3. Mass, Density, and Formation Constraints in the Compact, Sub-Earth Kepler-444 System including Two Mars-mass Planets

    NASA Astrophysics Data System (ADS)

    Mills, Sean M.; Fabrycky, Daniel C.

    2017-03-01

    Kepler-444 is a five-planet system around a host star approximately 11 billion years old. The five transiting planets all have sub-Earth radii and are in a compact configuration with orbital periods between 3 and 10 days. Here, we present a transit-timing analysis of the system using the full Kepler data set in order to determine the masses of the planets. Two planets, Kepler-444 d ({M}{{d}}={0.036}-0.020+0.065 {M}\\oplus ) and Kepler-444 e ({M}{{e}}={0.034}-0.019+0.059 {M}\\oplus ), have confidently detected masses due to their proximity to resonance that creates transit-timing variations. The mass ratio of these planets combined with the magnitude of possible star–planet tidal effects suggests that smooth disk migration over a significant distance is unlikely to have brought the system to its currently observed orbital architecture without significant post-formation perturbations.

  4. Using Dynamical Models to Predict the Terrestrial-Mass Free-Floating Planet Population

    NASA Astrophysics Data System (ADS)

    Barclay, Thomas; Quintana, Elisa V.

    2016-10-01

    In the classical picture of planet formation, planets form within circumstellar disks as a product of star formation. The material in the disk either forms into a planet, remains bound to the star, falls into the star, or is ejected from the system. We explore the properties of this ejected material using N-body simulations of the late stages of terrestrial planet formation. We find that in planetary systems like ours (with Jupiter and Saturn) about half the ejected material is in bodies less massive than the Moon and half is in bodies more massive than Mars. No planets more massive than half an Earth-mass, however, were ejected, primarily because most of the ejections occur before the timescales needed to grow an Earth-mass body. Without giant planets present in the system, very little material is ever ejected. We predict that future space-borne microlensing searches for free-floating terrestrial-mass planets, such as WFIRST, will discover large numbers of Mars-mass planets but will not make significant detections of Earth-mass planets.

  5. The Solar Twin Planet Search. V. Close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468

    NASA Astrophysics Data System (ADS)

    Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Ramírez, Iván; Asplund, Martin; Dreizler, Stefan; Yan, Hong-Liang; Shi, Jian-Rong; Lind, Karin; Ferraz-Mello, Sylvio; Galarza, Jhon Yana; dos Santos, Leonardo; Spina, Lorenzo; Maia, Marcelo Tucci; Alves-Brito, Alan; Monroe, TalaWanda; Casagrande, Luca

    2017-01-01

    Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances especially for them, which is crucial for studying the planet-star chemical connection with the highest precision. Aims: We aim to use solar twins to characterise the relationship between planet architecture and stellar chemical composition. Methods: We obtained high-precision (1 m s-1) radial velocities with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla Observatory and determined precise stellar elemental abundances ( 0.01 dex) using spectra obtained with the MIKE spectrograph on the Magellan 6.5 m telescope. Results: Our data indicate the presence of a planet with a minimum mass of 26 ± 4 Earth masses around the solar twin HIP 68468. The planet is more massive than Neptune (17 Earth masses), but unlike the distant Neptune in our solar system (30 AU), HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to that of Venus. The data also suggest the presence of a super-Earth with a minimum mass of 2.9 ± 0.8 Earth masses at 0.03 AU; if the planet is confirmed, it will be the fifth least massive radial velocity planet candidate discovery to date and the first super-Earth around a solar twin. Both isochrones (5.9 ± 0.4 Gyr) and the abundance ratio [Y/Mg] (6.4 ± 0.8 Gyr) indicate an age of about 6 billion years. The star is enhanced in refractory elements when compared to the Sun, and the refractory enrichment is even stronger after corrections for Galactic chemical evolution. We determined a nonlocal thermodynamic equilibrium Li abundance of 1.52 ± 0.03 dex, which is four times higher than what would be expected for the age of HIP 68468. The older age is also supported by the low log () (-5.05) and low jitter (<1 m s-1). Engulfment of a rocky planet of 6 Earth masses can explain the enhancement in both lithium and the

  6. Effect of planetary mass on the orbit of star-planet systems

    NASA Astrophysics Data System (ADS)

    Öztürk, O.; Erdem, A.

    2017-02-01

    Two main parameters, which determine the radial velocity semi-amplitude of the host star in a star-planet system, are the planet mass and the orbital period. In order to examine the effect of planet mass on the radial velocity semi-amplitude, we firstly select sensitive data of spectroscopic orbital solutions of 737 systems, given in the database of exoplanet.org. The selected systems are then categorized into 31 groups according to their orbital periods. For each group, an empirical relation between the radial velocity semi amplitude and the planet mass is obtained. In order to check the accuracy of these empirical relations, the measured and expected values of planet masses are compared.

  7. Planets across the HR diagram with the Transiting Exoplanet Survey Satellite Full Frame Images

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Pal, Andras; Wall, Matthew; Liang, Yu; Levine, Alan M.; Owens, Martin; Kraft Vanderspek, Roland; Seager, Sara; Ricker, George R.; TESS Science Team

    2017-06-01

    Discoveries from the Kepler Mission have revealed that planets close to their host stars are common, despite none in our solar system. The Transiting Exoplanet Survey Satellite (TESS) will perform a wide-field survey for planets over ~75%of the sky for the first time. The 30 min cadence TESS Full Frame Images (FFI) will provide observations of more than 10 million stars brighter than magnitude I=16. The FFI targets include stars from all spectral classes, with ages spanning the range ~10 Myr to ~10 Gyr and with metallicities ranging over more than 1 dex.The FFIs will provide an all-sky magnitude limited sample of short period planetary systems. The precision of TESS will enable planet to be discovered around stars ranging from M-dwarfs, to B-dwarfs. In contrast, the Kepler sample is restricted primarily to main-sequence FGK systems, while the TESS short cadence (2 min) stamps will be centered about cooler stars. We present the current status of the TESS full frame image (FFI) photometry and candidate detection pipeline. We update the predicted detection rates of sub-Neptunes, super-Neptunes and giant planets using simulated TESS images with realistic noise characteristics. We expect that TESS will find more than 20000 planets with sizes larger than 2 Earth radius around stars with very diverse properties. We discuss how these findings will help resolve many long standing questions, including the planet occurrence rateas a function of stellar mass, metallicity, and age. Many of these TESS planets will be suitable for ground-based follow up observations that willestablish masses, orbital obliquities and eccentricities, which will help improve our understanding of the formation channels of theseclose-in planets.

  8. A limit on the presence of Earth-mass planets around a Sun-like star

    SciTech Connect

    Agol, Eric; Steffen, Jason H.; /Fermilab

    2006-10-01

    We present a combined analysis of all publicly available, visible HST observations of transits of the planet HD 209458b. We derive the times of transit, planet radius, inclination, period, and ephemeris. The transit times are then used to constrain the existence of secondary planets in the system. We show that planets near an Earth mass can be ruled out in low-order mean-motion resonance, while planets less than an Earth mass are ruled out in interior, 2:1 resonance. We also present a combined analysis of the transit times and 68 high precision radial velocity measurements of the system. These results are compared to theoretical predictions for the constraints that can be placed on secondary 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. The Spitzer search for the transits of HARPS low-mass planets. II. Null results for 19 planets

    NASA Astrophysics Data System (ADS)

    Gillon, M.; Demory, B.-O.; Lovis, C.; Deming, D.; Ehrenreich, D.; Lo Curto, G.; Mayor, M.; Pepe, F.; Queloz, D.; Seager, S.; Ségransan, D.; Udry, S.

    2017-05-01

    Short-period super-Earths and Neptunes are now known to be very frequent around solar-type stars. Improving our understanding of these mysterious planets requires the detection of a significant sample of objects suitable for detailed characterization. Searching for the transits of the low-mass planets detected by Doppler surveys is a straightforward way to achieve this goal. Indeed, Doppler surveys target the most nearby main-sequence stars, they regularly detect close-in low-mass planets with significant transit probability, and their radial velocity data constrain strongly the ephemeris of possible transits. In this context, we initiated in 2010 an ambitious Spitzer multi-Cycle transit search project that targeted 25 low-mass planets detected by radial velocity, focusing mainly on the shortest-period planets detected by the HARPS spectrograph. We report here null results for 19 targets of the project. For 16 planets out of 19, a transiting configuration is strongly disfavored or firmly rejected by our data for most planetary compositions. We derive a posterior probability of 83% that none of the probed 19 planets transits (for a prior probability of 22%), which still leaves a significant probability of 17% that at least one of them does transit. Globally, our Spitzer project revealed or confirmed transits for three of its 25 targeted planets, and discarded or disfavored the transiting nature of 20 of them. Our light curves demonstrate for Warm Spitzer excellent photometric precisions: for 14 targets out of 19, we were able to reach standard deviations that were better than 50 ppm per 30 min intervals. Combined with its Earth-trailing orbit, which makes it capable of pointing any star in the sky and to monitor it continuously for days, this work confirms Spitzer as an optimal instrument to detect sub-mmag-deep transits on the bright nearby stars targeted by Doppler surveys. The photometric and radial velocity time series used in this work are only available at the

  11. Catastrophic Collisions in the Terrestrial Planet Zone and the Epoch of Terrestrial Planet Formation around Intermediate Mass Stars

    NASA Astrophysics Data System (ADS)

    Melis, Carl; Zuckerman, B.; Song, I.; Rhee, J. H.; Bessell, M. S.; Murphy, S. J.

    2010-01-01

    We have completed an extensive search for stars hosting terrestrial planet zone dust by cross-correlating the Tycho-2 and IRAS catalogs. Near-infrared to far-infrared excess emission has been discovered towards a 10-20 Myr old, A-type member of the Upper-Centaurus-Lupus association. The hot dust component ( 750 K) in combination with the high fractional infrared luminosity (0.4%) suggest a recent catastrophic collision between rocky bodies in this intermediate mass star's inner planetary system. Synthesis of all published incidences of intermediate mass stars with evidence for terrestrial planet zone dust suggests that catastrophic collisions analogous to the Moon-forming event in our Solar System occur around intermediate mass stars when the star is 10-30 Myr old. Funding for this research came from NASA grants and an LLNL-Minigrant to UCLA and from the Spitzer Visiting Graduate Student Program.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    Context. Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets. In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. Aims: During the past six years we have conducted a radial velocity follow-up program of 166 giant stars to detect substellar companions and to characterize their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. Methods: We took multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we computed precision radial velocities and derived atmospheric and physical parameters. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we detected the presence of several substellar companions. Results: We present four new planetary systems around the giant stars HIP 8541, HIP 74890, HIP 84056, and HIP 95124. Additionally, we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7+15.5-5.9% around stars with [Fe/H] ~ 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆ ~ 1.0 and 2.1 M⊙, with a maximum of f = 13.0+10.1-4.2% at M⋆ = 2.1 M⊙. Conclusions: We conclude that giant planets are preferentially formed around metal-rich stars. In addition, we conclude that they are more efficiently formed around more massive stars, in the stellar mass range of ~1.0-2.1 M⊙. These observational results confirm previous findings for solar

  13. 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.

  14. HABITABILITY OF EARTH-MASS PLANETS AND MOONS IN THE KEPLER-16 SYSTEM

    SciTech Connect

    Quarles, B.; Musielak, Z. E.; Cuntz, M. E-mail: zmusielak@uta.edu

    2012-05-01

    We demonstrate that habitable Earth-mass planets and moons can exist in the Kepler-16 system, known to host a Saturn-mass planet around a stellar binary, by investigating their orbital stability in the standard and extended habitable zone (HZ). We find that Earth-mass planets in satellite-like (S-type) orbits are possible within the standard HZ in direct vicinity of Kepler-16b, thus constituting habitable exomoons. However, Earth-mass planets cannot exist in planetary-like (P-type) orbits around the two stellar components within the standard HZ. Yet, P-type Earth-mass planets can exist superior to the Saturnian planet in the extended HZ pertaining to considerably enhanced back-warming in the planetary atmosphere if facilitated. We briefly discuss the potential detectability of such habitable Earth-mass moons and planets positioned in satellite and planetary orbits, respectively. The range of inferior and superior P-type orbits in the HZ is between 0.657-0.71 AU and 0.95-1.02 AU, respectively.

  15. 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)

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    We report the discovery of one newly confirmed planet (P = 66.06 days, R P = 2.68 ± 0.17 R ⊕) and mass determinations of two previously validated Kepler planets, Kepler-289 b (P = 34.55 days, R P = 2.15 ± 0.10 R ⊕) and Kepler-289-c (P = 125.85 days, R P = 11.59 ± 0.10 R ⊕), 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 * = 1.08 ± 0.02 M ⊙, R * = 1.00 ± 0.02 R ⊙, and T 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 ⊕, 4.0 ± 0.9M ⊕, and M = 132 ± 17 M ⊕, 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-3 for a planet of its mass, requiring a substantial H/He atmosphere of 2.1+0.8-0.3% by mass, and joins a growing population of low-mass, low-density planets. .

  16. 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

    2011-02-03

    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.

  17. 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.

  18. Dynamics of a Probable Earth-mass Planet in the GJ 832 System

    NASA Astrophysics Data System (ADS)

    Satyal, S.; Griffith, J.; Musielak, Z. E.

    2017-08-01

    The stability of planetary orbits around the GJ 832 star system, which contains inner (GJ 832c) and outer (GJ 832b) planets, is investigated numerically and a detailed phase-space analysis is performed. Special attention is given to the existence of stable orbits for a planet less than 15 M ⊕ that is injected between the inner and outer planets. Thus, numerical simulations are performed for three and four bodies in elliptical orbits (or circular for special cases) by using a large number of initial conditions that cover the selected phase-spaces of the planet’s orbital parameters. The results presented in the phase-space maps for GJ 832c indicate the least deviation of eccentricity from its nominal value, which is then used to determine its inclination regime relative to the star-outer planet plane. Also, the injected planet is found to display stable orbital configurations for at least one billion years. Then, the radial velocity curves based on the signature from the Keplerian motion are generated for the injected planets with masses 1 M ⊕ to 15 M ⊕ in order to estimate their semimajor axes and mass limits. The synthetic RV signal suggests that an additional planet of mass ≤15 M ⊕ with a dynamically stable configuration may be residing between 0.25 and 2.0 au from the star. We have provided an estimated number of RV observations for the additional planet that is required for further observational verification.

  19. Obtaining the Mass and Radius of Extra-Solar Giant Planets

    NASA Technical Reports Server (NTRS)

    Castellano, Tim; Mead, Susan (Technical Monitor)

    1998-01-01

    The scientific utility and feasibility of detecting transits of the 9 known extrasolar planets is explored. A transit of a solar-like star by a Jupiter mass planet produces a 1% decrease in the amount of light received from the star. Transit observation will remove the ambiguity in the measurement of the planetary mass inherent in the radial velocity method and confirm the planet's existence. The 9 known planets have a 33% chance of producing at least one observable transit. Additional extrasolar planet detections from the radial velocity surveys will increase this probability to greater than 90%. The radius of the planet can be determined by the fractional decrease in light received during transit. The mass and radius may distinguish rocky or gas giant planets from brown dwarfs. The probability of detection, the transit signal size and duration, and predictions of the transit times (including errors) are calculated for circular and elliptical orbits. Observational limits are investigated and it is shown that small telescopes and existing detectors are adequate enough to achieve the 0.1% photometry necessary to detect transits of the known extrasolar planets.

  20. Eleven Multiplanet Systems from K2 Campaigns 1 and 2 and the Masses of Two Hot Super-Earths

    NASA Astrophysics Data System (ADS)

    Sinukoff, Evan; Howard, Andrew W.; Petigura, Erik A.; Schlieder, Joshua E.; Crossfield, Ian J. M.; Ciardi, David R.; Fulton, Benjamin J.; Isaacson, Howard; Aller, Kimberly M.; Baranec, Christoph; Beichman, Charles A.; Hansen, Brad M. S.; Knutson, Heather A.; Law, Nicholas M.; Liu, Michael C.; Riddle, Reed; Dressing, Courtney D.

    2016-08-01

    We present a catalog of 11 multiplanet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven two-planet systems and four three-planet systems. These planets stem from a systematic search of the K2 photometry for all dwarf stars observed by K2 in these fields. We precisely characterized the host stars with adaptive optics imaging and analysis of high-resolution optical spectra from Keck/HIRES and medium-resolution spectra from IRTF/SpeX. We confirm two planet candidates by mass detection and validate the remaining 24 candidates to >99% confidence. Thirteen planets were previously validated or confirmed by other studies, and 24 were previously identified as planet candidates. The planets are mostly smaller than Neptune (21/26 planets), as in the Kepler mission, and all have short periods (P < 50 days) due to the duration of the K2 photometry. The host stars are relatively bright (most have Kp < 12.5 mag) and are amenable to follow-up characterization. For K2-38, we measured precise radial velocities using Keck/HIRES and provide initial estimates of the planet masses. K2-38b is a short-period super-Earth with a radius of 1.55+/- 0.16 R ⊕, a mass of 12.0+/- 2.9 M ⊕, and a high density consistent with an iron-rich composition. The outer planet K2-38c is a lower-density sub-Neptune-size planet with a radius of 2.42+/- 0.29 R ⊕ and a mass of 9.9+/- 4.6 M ⊕ that likely has a substantial envelope. This new planet sample demonstrates the capability of K2 to discover numerous planetary systems around bright stars.

  1. A COLD NEPTUNE-MASS PLANET OGLE-2007-BLG-368Lb: COLD NEPTUNES ARE COMMON

    SciTech Connect

    Sumi, T.; Abe, F.; Fukui, A. E-mail: abe@stelab.nagoya-u.ac.j

    2010-02-20

    We present the discovery of a Neptune-mass planet OGLE-2007-BLG-368Lb with a planet-star mass ratio of q = [9.5 +- 2.1] x 10{sup -5} via gravitational microlensing. The planetary deviation was detected in real-time thanks to the high cadence of the Microlensing Observations in Astrophysics survey, real-time light-curve monitoring and intensive follow-up observations. A Bayesian analysis returns the stellar mass and distance at M{sub l} = 0.64{sup +0.21}{sub -0.26} M{sub sun} and D{sub l} = 5.9{sup +0.9}{sub -1.4} kpc, respectively, so the mass and separation of the planet are M{sub p} = 20{sup +7}{sub -8} M{sub +} and a = 3.3{sup +1.4}{sub -0.8} AU, respectively. This discovery adds another cold Neptune-mass planet to the planetary sample discovered by microlensing, which now comprises four cold Neptune/super-Earths, five gas giant planets, and another sub-Saturn mass planet whose nature is unclear. The discovery of these 10 cold exoplanets by the microlensing method implies that the mass ratio function of cold exoplanets scales as dN{sub pl}/dlog q {proportional_to} q {sup -0.7+}-{sup 0.2} with a 95% confidence level upper limit of n < -0.35 (where dN{sub pl}/dlog q {proportional_to} q{sup n} ). As microlensing is most sensitive to planets beyond the snow-line, this implies that Neptune-mass planets are at least three times more common than Jupiters in this region at the 95% confidence level.

  2. Just How Earth-like are Extrasolar Super-Earths? Constraints on H+He Envelope Fractions from Kepler's Planet Candidates

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Lopez, E.; Kepler Team; SAMSI Bayesian Characterization of Exoplanet Populations Working Group

    2013-10-01

    With 3500 planetary candidates discovered in its first 3 years of data, the Kepler Mission promises to answer one of the most fundamental questions posed in exoplanetary research: what kinds of planets occur most often in our Galaxy? As Kepler primarily yields planetary radii and orbital periods, it has enabled numerous studies of the occurrence rate of planets as a function of these variables. Unfortunately, the full mass distribution, and thus a direct measure of these planets' possible compositions, remains elusive due to the unsuitability of these faint targets for radial velocity follow-up and the relative rareness of transit timing variations. We show, however, that relatively straightforward models of planetary evolution in an irradiated environment can make some progress without this full mass distribution towards understanding bulk compositions of the abundant Super-Earth/Sub-Neptunes that Kepler has discovered. In particular, we constrain the distribution of envelope fractions, i.e. the fraction of a planet's mass that is in a gaseous hydrogen and helium envelope around its rocky core, for this exoplanet population that has no analogs in our Solar System.

  3. Just How Earth-like are Extrasolar Super-Earths? Constraints on H+He Envelope Fractions from Kepler's Planet Candidates

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Lopez, E.; Kepler Team; SAMSI Bayesian Characterization of Exoplanet Populations Working Group

    2014-01-01

    With 3500 planetary candidates discovered in its first 3 years of data, the Kepler Mission promises to answer one of the most fundamental questions posed in exoplanetary research: what kinds of planets occur most often in our Galaxy? As Kepler primarily yields planetary radii and orbital periods, it has enabled numerous studies of the occurrence rate of planets as a function of these variables. Unfortunately, the full mass distribution, and thus a direct measure of these planets' possible compositions, remains elusive due to the unsuitability of these faint targets for radial velocity follow-up and the relative rareness of transit timing variations. We show, however, that relatively straightforward models of planetary evolution in an irradiated environment can make some progress without this full mass distribution towards understanding bulk compositions of the abundant Super-Earth/Sub-Neptunes that Kepler has discovered. In particular, we constrain the distribution of envelope fractions, i.e. the fraction of a planet's mass that is in a gaseous hydrogen and helium envelope around its rocky core, for this exoplanet population that has no analogs in our Solar System. This research builds on collaborations between astronomers and statisticians forged during a three week workshop on "Modern Statistical and Computational Methods for Analysis of Kepler Data" at SAMSI in June 2013.

  4. SALT observations of the chromospheric activity of transiting planet hosts: mass-loss and star-planet interactions★

    NASA Astrophysics Data System (ADS)

    Staab, D.; Haswell, C. A.; Smith, Gareth D.; Fossati, L.; Barnes, J. R.; Busuttil, R.; Jenkins, J. S.

    2017-04-01

    We measured the chromospheric activity of the four hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 and WASP-103 to search for anomalous values caused by the close-in companions. The Mount Wilson Ca II H & K S-index was calculated for each star using observations taken with the Robert Stobie Spectrograph at the Southern African Large Telescope. The activity level of WASP-43 is anomalously high relative to its age and falls among the highest values of all known main-sequence stars. We found marginal evidence that the activity of WASP-103 is also higher than expected from the system age. We suggest that for WASP-43 and WASP-103 star-planet interactions (SPI) may enhance the Ca II H & K core emission. The activity levels of WASP-51/HAT-P-30 and WASP-72 are anomalously low, with the latter falling below the basal envelope for both main-sequence and evolved stars. This can be attributed to circumstellar absorption due to planetary mass-loss, though absorption in the interstellar medium may contribute. A quarter of known short-period planet hosts exhibit anomalously low activity levels, including systems with hot Jupiters and low-mass companions. Since SPI can elevate and absorption can suppress the observed chromospheric activity of stars with close-in planets, their Ca II H & K activity levels are an unreliable age indicator. Systems where the activity is depressed by absorption from planetary mass-loss are key targets for examining planet compositions through transmission spectroscopy.

  5. Kepler’s Low-Mass, Low Density Planets Characterized via Transit Timing

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Ford, Eric B.; Lissauer, Jack; Rowe, Jason; Fabrycky, Daniel

    2015-08-01

    The Kepler mission has revealed an abundance of planets in a regime of mass and size that is absent from the Solar System. This includes systems of high multiplicity within 1 AU, where low-mass volatile-rich planets have been observed in compact orbital configurations, as have smaller, rocky planets. The existing sample of characterized planets on the mass-radius diagram shows no abrupt transition from rocky planets to those that must be volatile-rich, but characteristic trends are beginning to emerge. More precise characterizations of planets by mass, radius, and incident flux are revealing fundamental properties of a common class of exoplanets.There is a small sample of low mass exoplanets with known masses and radii, whose radii are known from transit depths, and whose masses are determined from radial velocity spectroscopy (RV). In the super-Earth mass range, detectability limits this sample to planets that have short orbital periods, and high incident fluxes.In the absence of mass determinations via RV observations, transit timing variations (TTVs) offer a chance to probe perturbations between planets that pass close to one another or are near resonance, and hence dynamical fits to observed transit times can be used to measure planetary masses and orbital parameters. Such modeling with Kepler data probes planetary masses over orbital periods ranging from ~5-200 days, complementing the sample of RV detections, but also with some overlap.In addition, dynamical fits to observed TTVs can tightly constrain the orbital eccentricity vectors in select cases, which can, alongside the transit light curve, tightly constrain the density and radius of the host star, and hence reduce the uncertainty on planetary radius.TTV studies have revealed a class of low-mass, low-density objects with a substantial mass fraction in the form of a voluminous H-rich atmosphere. We will present new precise planetary mass characterizations from TTVs. We find that super-Earth mass planets

  6. Stability of Earth-mass Planets in the Kepler-68 System

    NASA Astrophysics Data System (ADS)

    Kane, Stephen R.

    2015-11-01

    A key component of characterizing multi-planet exosystems is testing the orbital stability based on the observed properties. Such characterization not only tests the validity of how observations are interpreted but can also place additional constraints upon the properties of the detected planets. The Kepler mission has identified hundreds of multi-planet systems but there are a few that have additional non-transiting planets and also have well characterized host stars. Kepler-68 is one such system for which we are able to provide a detailed study of the orbital dynamics. We use the stellar parameters to calculate the extent of the habitable zone (HZ) for this system, showing that the outer planet lies within that region. We use N-body integrations to study the orbital stability of the system, in particular placing an orbital inclination constraint on the outer planet of i > 5°. Finally, we present the results of an exhaustive stability simulation that investigates possible locations of stable orbits for an Earth-mass planet. We show that there are several islands of stability within the HZ that could harbor such a planet, most particularly at the 2:3 mean motion resonance with the outer planet.

  7. 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.

  8. 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.

  9. Resolving the sin(I) Degeneracy in Low-mass Multi-planet Systems

    NASA Astrophysics Data System (ADS)

    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.

  10. The Mass of Kepler-93b and The Composition of Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Dressing, Courtney D.; Charbonneau, David; Dumusque, Xavier; Gettel, Sara; Pepe, Francesco; Collier Cameron, Andrew; Latham, David W.; Molinari, Emilio; Udry, Stéphane; Affer, Laura; Bonomo, Aldo S.; Buchhave, Lars A.; Cosentino, Rosario; Figueira, Pedro; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Haywood, Raphaëlle D.; Johnson, John Asher; Lopez-Morales, Mercedes; Lovis, Christophe; Malavolta, Luca; Mayor, Michel; Micela, Giusi; Motalebi, Fatemeh; Nascimbeni, Valerio; Phillips, David F.; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Szentgyorgyi, Andrew; Watson, Chris

    2015-02-01

    Kepler-93b is a 1.478 ± 0.019 R ⊕ planet with a 4.7 day period around a bright (V = 10.2), astroseismically characterized host star with a mass of 0.911 ± 0.033 M ⊙ and a radius of 0.919 ± 0.011 R ⊙. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02 ± 0.68 M ⊕. The corresponding high density of 6.88 ± 1.18 g cm-3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6 M ⊕, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6 M ⊕. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6 M ⊕ planets. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  11. THE MASS OF Kepler-93b AND THE COMPOSITION OF TERRESTRIAL PLANETS

    SciTech Connect

    Dressing, Courtney D.; Charbonneau, David; Dumusque, Xavier; Gettel, Sara; Latham, David W.; Buchhave, Lars A.; Johnson, John Asher; Lopez-Morales, Mercedes; Pepe, Francesco; Udry, Stéphane; Lovis, Christophe; Collier Cameron, Andrew; Haywood, Raphaëlle D.; Molinari, Emilio; Cosentino, Rosario; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Affer, Laura; Bonomo, Aldo S.; Figueira, Pedro; and others

    2015-02-20

    Kepler-93b is a 1.478 ± 0.019 R {sub ⊕} planet with a 4.7 day period around a bright (V = 10.2), astroseismically characterized host star with a mass of 0.911 ± 0.033 M {sub ☉} and a radius of 0.919 ± 0.011 R {sub ☉}. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02 ± 0.68 M {sub ⊕}. The corresponding high density of 6.88 ± 1.18 g cm{sup –3} is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6 M {sub ⊕}, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6 M {sub ⊕}. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6 M {sub ⊕} planets.

  12. Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes

    NASA Astrophysics Data System (ADS)

    Stassun, Keivan G.; Collins, Karen A.; Gaudi, B. Scott

    2017-03-01

    We present empirical measurements of the radii of 116 stars that host transiting planets. These radii are determined using only direct observables—the bolometric flux at Earth, the effective temperature, and the parallax provided by the Gaia first data release—and thus are virtually model independent, with extinction being the only free parameter. We also determine each star’s mass using our newly determined radius and the stellar density, a virtually model independent quantity itself from previously published transit analyses. These stellar radii and masses are in turn used to redetermine the transiting-planet radii and masses, again using only direct observables. The median uncertainties on the stellar radii and masses are 8% and 30%, respectively, and the resulting uncertainties on the planet radii and masses are 9% and 22%, respectively. These accuracies are generally larger than previously published model-dependent precisions of 5% and 6% on the planet radii and masses, respectively, but the newly determined values are purely empirical. We additionally report radii for 242 stars hosting radial-velocity (non-transiting) planets, with a median achieved accuracy of ≈2%. Using our empirical stellar masses we verify that the majority of putative “retired A stars” in the sample are indeed more massive than ˜1.2 {M}⊙ . Most importantly, the bolometric fluxes and angular radii reported here for a total of 498 planet host stars—with median accuracies of 1.7% and 1.8%, respectively—serve as a fundamental data set to permit the re-determination of transiting-planet radii and masses with the Gaia second data release to ≈3% and ≈5% accuracy, better than currently published precisions, and determined in an entirely empirical fashion.

  13. 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.

  14. Mg/Si Mineralogical Ratio of Low-Mass Planet Hosts. Correction for the NLTE Effects

    NASA Astrophysics Data System (ADS)

    Adibekyan, V.; Gonçalves da Silva, H. M.; Sousa, S. G.; Santos, N. C.; Delgado Mena, E.; Hakobyan, A. A.

    2017-09-01

    Mg/Si and Fe/Si ratios are important parameters that control the composition of rocky planets. In this work we applied non-LTE correction to the Mg and Si abundances of stars with and without planets to confirm/reject our previous findings that [Mg/Si] atmospheric abundance is systematically higher for Super-Earth/Neptune-mass planet hosts than stars without planets. Our results show that the small differences of stellar parameters observed in these two groups of stars are not responsible for the already reported difference in the [Mg/Si] ratio. Thus, the high [Mg/Si] ratio of Neptunian hosts is probably related to the formation efficiency of these planets in such environments.

  15. Exoplanet dynamics. Asynchronous rotation of Earth-mass planets in the habitable zone of lower-mass stars.

    PubMed

    Leconte, Jérémy; Wu, Hanbo; Menou, Kristen; Murray, Norman

    2015-02-06

    Planets in the habitable zone of lower-mass stars are often assumed to be in a state of tidally synchronized rotation, which would considerably affect their putative habitability. Although thermal tides cause Venus to rotate retrogradely, simple scaling arguments tend to attribute this peculiarity to the massive Venusian atmosphere. Using a global climate model, we show that even a relatively thin atmosphere can drive terrestrial planets' rotation away from synchronicity. We derive a more realistic atmospheric tide model that predicts four asynchronous equilibrium spin states, two being stable, when the amplitude of the thermal tide exceeds a threshold that is met for habitable Earth-like planets with a 1-bar atmosphere around stars more massive than ~0.5 to 0.7 solar mass. Thus, many recently discovered terrestrial planets could exhibit asynchronous spin-orbit rotation, even with a thin atmosphere. Copyright © 2015, American Association for the Advancement of Science.

  16. No large population of unbound or wide-orbit Jupiter-mass planets.

    PubMed

    Mróz, Przemek; Udalski, Andrzej; Skowron, Jan; Poleski, Radosław; Kozłowski, Szymon; Szymański, Michał K; Soszyński, Igor; Wyrzykowski, Łukasz; Pietrukowicz, Paweł; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

    2017-08-10

    Planet formation theories predict that some planets may be ejected from their parent systems as result of dynamical interactions and other processes. Unbound planets can also be formed through gravitational collapse, in a way similar to that in which stars form. A handful of free-floating planetary-mass objects have been discovered by infrared surveys of young stellar clusters and star-forming regions as well as wide-field surveys, but these studies are incomplete for objects below five Jupiter masses. Gravitational microlensing is the only method capable of exploring the entire population of free-floating planets down to Mars-mass objects, because the microlensing signal does not depend on the brightness of the lensing object. A characteristic timescale of microlensing events depends on the mass of the lens: the less massive the lens, the shorter the microlensing event. A previous analysis of 474 microlensing events found an excess of ten very short events (1-2 days)-more than known stellar populations would suggest-indicating the existence of a large population of unbound or wide-orbit Jupiter-mass planets (reported to be almost twice as common as main-sequence stars). These results, however, do not match predictions of planet-formation theories and surveys of young clusters. Here we analyse a sample of microlensing events six times larger than that of ref. 11 discovered during the years 2010-15. Although our survey has very high sensitivity (detection efficiency) to short-timescale (1-2 days) microlensing events, we found no excess of events with timescales in this range, with a 95 per cent upper limit on the frequency of Jupiter-mass free-floating or wide-orbit planets of 0.25 planets per main-sequence star. We detected a few possible ultrashort-timescale events (with timescales of less than half a day), which may indicate the existence of Earth-mass and super-Earth-mass free-floating planets, as predicted by planet-formation theories.

  17. No large population of unbound or wide-orbit Jupiter-mass planets

    NASA Astrophysics Data System (ADS)

    Mróz, Przemek; Udalski, Andrzej; Skowron, Jan; Poleski, Radosław; Kozłowski, Szymon; Szymański, Michał K.; Soszyński, Igor; Wyrzykowski, Łukasz; Pietrukowicz, Paweł; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

    2017-08-01

    Planet formation theories predict that some planets may be ejected from their parent systems as result of dynamical interactions and other processes. Unbound planets can also be formed through gravitational collapse, in a way similar to that in which stars form. A handful of free-floating planetary-mass objects have been discovered by infrared surveys of young stellar clusters and star-forming regions as well as wide-field surveys, but these studies are incomplete for objects below five Jupiter masses. Gravitational microlensing is the only method capable of exploring the entire population of free-floating planets down to Mars-mass objects, because the microlensing signal does not depend on the brightness of the lensing object. A characteristic timescale of microlensing events depends on the mass of the lens: the less massive the lens, the shorter the microlensing event. A previous analysis of 474 microlensing events found an excess of ten very short events (1-2 days)—more than known stellar populations would suggest—indicating the existence of a large population of unbound or wide-orbit Jupiter-mass planets (reported to be almost twice as common as main-sequence stars). These results, however, do not match predictions of planet-formation theories and surveys of young clusters. Here we analyse a sample of microlensing events six times larger than that of ref. 11 discovered during the years 2010-15. Although our survey has very high sensitivity (detection efficiency) to short-timescale (1-2 days) microlensing events, we found no excess of events with timescales in this range, with a 95 per cent upper limit on the frequency of Jupiter-mass free-floating or wide-orbit planets of 0.25 planets per main-sequence star. We detected a few possible ultrashort-timescale events (with timescales of less than half a day), which may indicate the existence of Earth-mass and super-Earth-mass free-floating planets, as predicted by planet-formation theories.

  18. Star Masses and Star-Planet Distances for Earth-like Habitability

    PubMed Central

    2017-01-01

    Abstract This paper presents statistical estimates for the location and duration of habitable zones (HZs) around stars of different mass. The approach is based upon the assumption that Earth's location, and the Sun's mass, should not be highly atypical of inhabited planets. The results support climate-model-based estimates for the location of the Sun's HZ except models giving a present-day outer-edge beyond 1.64 AU. The statistical approach also demonstrates that there is a habitability issue for stars smaller than 0.65 solar masses since, otherwise, Earth would be an extremely atypical inhabited world. It is difficult to remove this anomaly using the assumption that poor habitability of planets orbiting low-mass stars results from unfavorable radiation regimes either before, or after, their stars enter the main sequence. However, the anomaly is well explained if poor habitability results from tidal locking of planets in the HZs of small stars. The expected host-star mass for planets with intelligent life then has a 95% confidence range of 0.78 M⊙ < M < 1.04 M⊙, and the range for planets with at least simple life is 0.57 M⊙ < M < 1.64 M⊙. Key Words: Habitability—Habitable zone—Anthropic—Red dwarfs—Initial mass function. Astrobiology 17, 61–77. PMID:28103107

  19. Star Masses and Star-Planet Distances for Earth-like Habitability.

    PubMed

    Waltham, David

    2017-01-01

    This paper presents statistical estimates for the location and duration of habitable zones (HZs) around stars of different mass. The approach is based upon the assumption that Earth's location, and the Sun's mass, should not be highly atypical of inhabited planets. The results support climate-model-based estimates for the location of the Sun's HZ except models giving a present-day outer-edge beyond 1.64 AU. The statistical approach also demonstrates that there is a habitability issue for stars smaller than 0.65 solar masses since, otherwise, Earth would be an extremely atypical inhabited world. It is difficult to remove this anomaly using the assumption that poor habitability of planets orbiting low-mass stars results from unfavorable radiation regimes either before, or after, their stars enter the main sequence. However, the anomaly is well explained if poor habitability results from tidal locking of planets in the HZs of small stars. The expected host-star mass for planets with intelligent life then has a 95% confidence range of 0.78 M⊙ < M < 1.04 M⊙, and the range for planets with at least simple life is 0.57 M⊙ < M < 1.64 M⊙. Key Words: Habitability-Habitable zone-Anthropic-Red dwarfs-Initial mass function. Astrobiology 17, 61-77.

  20. The CRIRES Search for Planets Around the Lowest-Mass Stars: Introduction and First Results

    NASA Astrophysics Data System (ADS)

    Bean, Jacob; Seifahrt, A.; Reiners, A.; Dreizler, S.; Hartman, H.; Nilsson, H.; Wiedemann, G.; Henry, T.

    2010-01-01

    We are currently carrying out a search for planets around the lowest-mass stars using the CRIRES instrument at the VLT under the auspices of an ESO Large Programme. The main purposes of this work are to illuminate the correlation between stellar mass and planet formation, improve the census of planets, and identify new planets that can be followed-up for detailed study. We have developed, and are utilizing a new type of gas cell for obtaining high-precision radial velocities of late-type stars in the nIR spectral region. Observations in the nIR offer the advantages in that the targetted stars are bright enough for high-precision spectroscopy, and that the noise contribution from stellar activity is significantly reduced. We will give an introduction to the survey and present some preliminary results.

  1. The Dharma Planet Survey of Low-mass and Habitable Rocky Planets around Nearby Solar-type Stars

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Ma, Bo; Jeram, Sarik; Sithajan, Sirinrat; Singer, Michael; Muterspaugh, Matthew W.; Varosi, Frank; Schofield, Sidney; Liu, Jian; Kimock, Benjamin; Powell, Scott; Williamson, Michael W.; Herczeg, Aleczander; Grantham, Jim; Stafford, Greg; Hille, Bruce; Rosenbaum, Gary; Savage, David; Bland, Steve; Hoscheidt, Joseph; Swindle, Scott; Waidanz, Melanie; Petersen, Robert; Grieves, Nolan; Zhao, Bo; Cassette, Anthony; Chun, Andrew; Avner, Louis; Barnes, Rory; Tan, Jonathan C.; Lopez, Eric; Dai, Ruijia

    2017-01-01

    The Dharma Planet Survey (DPS) aims to monitor ~150 nearby very bright FGK dwarfs (most of them brighter than V=7) during 2016-2019 using the TOU optical very high resolution spectrograph (R~100,000, 380-900nm) at the dedicated 50-inch Robotic Telescope on Mt. Lemmon. Operated in high vacuum (<0.01mTorr) with precisely controlled temperature (~1 mK), TOU has delivered ~ 0.5 m/s (RMS) long-term instrument stability, which is a factor of two times more stable than any of existing Doppler instruments to our best knowledge. DPS aims at reaching better than 0.5 m/s (a goal of 0.2 m/s) Doppler measurement precision for bright survey targets. With very high RV precision and high cadence (~100 observations per target randomly spread over 450 days), a large number of rocky planets, including possible habitable ones, are expected to be detected. The discovery of a Neptune mass planet and early survey results will be announced.

  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. An Earth-mass Planet in a 1 au Orbit around an Ultracool Dwarf

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Yee, J. C.; Calchi Novati, S.; Gould, A.; Lee, C.-U.; Beichman, C.; Bryden, G.; Carey, S.; Gaudi, B. S.; Henderson, C. B.; Zhu, W.; Spitzer Team; Albrow, M. D.; Cha, S.-M.; Chung, S.-J.; Han, C.; Hwang, K.-H.; Jung, Y. K.; Kim, D.-J.; Kim, H.-W.; Kim, S.-L.; Lee, Y.; Park, B.-G.; Pogge, R. W.; Ryu, Y.-H.; Shin, I.-G.; KMTNet Group

    2017-05-01

    We combine Spitzer and ground-based Korea Microlensing Telescope Network microlensing observations to identify and precisely measure an Earth-mass ({1.43}-0.32+0.45{M}\\oplus ) planet OGLE-2016-BLG-1195Lb at {1.16}-0.13+0.16 {au} orbiting a {0.078}-0.012+0.016{M}⊙ ultracool dwarf. This is the lowest-mass microlensing planet to date. At {3.91}-0.46+0.42 kpc, it is the third consecutive case among the Spitzer “Galactic distribution” planets toward the Galactic bulge that lies in the Galactic disk as opposed to the bulge itself, hinting at a skewed distribution of planets. Together with previous microlensing discoveries, the seven Earth-size planets orbiting the ultracool dwarf TRAPPIST-1, and the detection of disks around young brown dwarfs, OGLE-2016-BLG-1195Lb suggests that such planets might be common around ultracool dwarfs. It therefore sheds light on the formation of both ultracool dwarfs and planetary systems at the limit of low-mass protoplanetary disks.

  4. Star Masses and Star-Planet Distances for Earth-like Habitability

    NASA Astrophysics Data System (ADS)

    Waltham, David

    2017-01-01

    This paper presents statistical estimates for the location and duration of habitable zones (HZs) around stars of different mass. The approach is based upon the assumption that Earth's location, and the Sun's mass, should not be highly atypical of inhabited planets. The results support climate-model-based estimates for the location of the Sun's HZ except models giving a present-day outer-edge beyond 1.64 AU. The statistical approach also demonstrates that there is a habitability issue for stars smaller than 0.65 solar masses since, otherwise, Earth would be an extremely atypical inhabited world. It is difficult to remove this anomaly using the assumption that poor habitability of planets orbiting low-mass stars results from unfavorable radiation regimes either before, or after, their stars enter the main sequence. However, the anomaly is well explained if poor habitability results from tidal locking of planets in the HZs of small stars. The expected host-star mass for planets with intelligent life then has a 95% confidence range of 0.78 M⊙ < M < 1.04 M⊙, and the range for planets with at least simple life is 0.57 M⊙ < M < 1.64 M⊙.

  5. 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.

  6. FORMATION OF GIANT PLANETS BY DISK INSTABILITY ON WIDE ORBITS AROUND PROTOSTARS WITH VARIED MASSES

    SciTech Connect

    Boss, Alan P.

    2011-04-10

    Doppler surveys have shown that more massive stars have significantly higher frequencies of giant planets inside {approx}3 AU than lower mass stars, consistent with giant planet formation by core accretion. Direct imaging searches have begun to discover significant numbers of giant planet candidates around stars with masses of {approx}1 M{sub sun} to {approx}2 M{sub sun} at orbital distances of {approx}20 AU to {approx}120 AU. Given the inability of core accretion to form giant planets at such large distances, gravitational instabilities of the gas disk leading to clump formation have been suggested as the more likely formation mechanism. Here, we present five new models of the evolution of disks with inner radii of 20 AU and outer radii of 60 AU, for central protostars with masses of 0.1, 0.5, 1.0, 1.5, and 2.0 M{sub sun}, in order to assess the likelihood of planet formation on wide orbits around stars with varied masses. The disk masses range from 0.028 M{sub sun} to 0.21 M{sub sun}, with initial Toomre Q stability values ranging from 1.1 in the inner disks to {approx}1.6 in the outer disks. These five models show that disk instability is capable of forming clumps on timescales of {approx}10{sup 3} yr that, if they survive for longer times, could form giant planets initially on orbits with semimajor axes of {approx}30 AU to {approx}70 AU and eccentricities of {approx}0 to {approx}0.35, with initial masses of {approx}1 M{sub Jup} to {approx}5 M{sub Jup}, around solar-type stars, with more protoplanets forming as the mass of the protostar (and protoplanetary disk) is increased. In particular, disk instability appears to be a likely formation mechanism for the HR 8799 gas giant planetary system.

  7. Measurement of Planet Masses with Transit Timing Variations Due to Synodic “Chopping” Effects

    NASA Astrophysics Data System (ADS)

    Deck, Katherine M.; Agol, Eric

    2015-04-01

    Gravitational interactions between planets in transiting exoplanetary systems lead to variations in the times of transit that are diagnostic of the planetary masses and the dynamical state of the system. Here we show that synodic “chopping” contributions to these transit timing variations (TTVs) can be used to uniquely measure the masses of planets without full dynamical analyses involving direct integration of the equations of motion. We present simple analytic formulae for the chopping signal, which are valid (generally \\lt 10% error) for modest eccentricities e≲ 0.1. Importantly, these formulae primarily depend on the mass of the perturbing planet, and therefore the chopping signal can be used to break the mass/free-eccentricity degeneracy, which can appear for systems near first-order mean motion resonances. Using a harmonic analysis, we apply these TTV formulae to a number of Kepler systems, which had been previously modeled with full dynamical analyses. We show that when chopping is measured, the masses of both planets can be determined uniquely, in agreement with previous results, but without the need for numerical orbit integrations. This demonstrates how mass measurements from TTVs may primarily arise from an observable chopping signal. The formula for chopping can also be used to predict the number of transits and timing precision required for future observations, such as those made by TESS or PLATO, in order to infer planetary masses through analysis of TTVs.

  8. Korean-Japanese Planet Search Program: Substellar Companions around Intermediate-Mass Giants

    NASA Astrophysics Data System (ADS)

    Omiya, Masashi; Han, Inwoo; Izumiura, Hideyuki; Lee, Byeong-Cheol; Sato, Bun'ei; Kim, Kang-Min; Yoon, Tae Seog; Kambe, Eiji; Yoshida, Michitoshi; Masuda, Seiji; Toyota, Eri; Urakawa, Seitaro; Takada-Hidai, Masahide

    2011-03-01

    A Korean-Japanese planet search program has been carried out using the 1.8m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea, and the 1.88m telescope at Okayama Astrophysical Observatory (OAO) in Japan to search for planets around intermediate-mass giant stars. The program aims to show the properties of planetary systems around such stars by precise Doppler survey of about 190 G or K type giants together with collaborative surveys of the East-Asian Planet Search Network. So far, we detected two substellar companions around massive intermediate-mass giants in the Korean-Japanese planet search program. One is a brown dwarf-mass companion with 37.6 MJ orbiting a giant HD 119445 with 3.9 Msolar, which is the most massive brown dwarf companion among those found around intermediate-mass giants. The other is a planetary companion with 1.8 MJ orbiting a giant star with 2.4 Msolar, which is the lowest-mass planetary companion among those detected around giant stars with >1.9 Msolar. Plotting these systems on companion mass vs. stellar mass diagram, there seem to exist two unpopulated regions of substellar companions around giants with 1.5-3 Msolar and planetary companions orbiting giants with 2.4-4 Msolar. The existence of these possible unpopulated regions supports a current characteristic view that more massive substellar companions tend to exist around more massive stars.

  9. MOA-2011-BLG-028Lb: A Neptune-mass Microlensing Planet in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Udalski, A.; Poleski, R.; Kozłowski, S.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Dominik, M.; Jørgensen, U. G.; Bozza, V.; Harpsøe, K.; Hundertmark, M.; Skottfelt, J.; MiNDSTEp Collaboration

    2016-03-01

    We present the discovery of a Neptune-mass planet orbiting a 0.8+/- 0.3{M}⊙ star in the Galactic bulge. The planet manifested itself during the microlensing event MOA-2011-BLG-028/OGLE-2011-BLG-0203 as a low-mass companion to the lens star. The analysis of the light curve provides the measurement of the mass ratio (1.2+/- 0.2)× {10}-4, which indicates that the mass of the planet is 12-60 Earth masses. The lensing system is located at 7.3 ± 0.7 kpc away from the Earth near the direction of Baade’s Window. The projected separation of the planet at the time of the microlensing event was 3.1-5.2 au. Although the microlens parallax effect is not detected in the light curve of this event, preventing the actual mass measurement, the uncertainties of mass and distance estimation are narrowed by the measurement of the source star proper motion on the OGLE-III images spanning eight years, and by the low amount of blended light seen, proving that the host star cannot be too bright and massive. We also discuss the inclusion of undetected parallax and orbital motion effects into the models and their influence onto the final physical parameters estimates. Based on observations obtained with the 1.3 m Warsaw telescope at the Las Campanas Observatory operated by the Carnegie Institution of Washington.

  10. Measuring Masses and Densities of Small Planets found by NASA's Kepler Spacecraft with Radial Velocity Measurements from Keck/HIRES

    NASA Astrophysics Data System (ADS)

    Isaacson, Howard T.; Marcy, G.; Rowe, J.; Kepler Team

    2013-06-01

    We use the Keck telescope and HIRES spectrometer to measure the masses of Kepler planet candidates. Analysis of 22 Kepler-identified planetary systems, holding 42 transiting planets (candidates) and 8 newly discovered non-transiting planets are presented herein. Combining the planet radius measurements from Kepler with mass measurements from Keck, we constrain the bulk density of short period planets that range in size from 1.0 to 3.0 Earth radii. Extensive ground based observations made by the Kepler Follow-up Program (KFOP) have provided extensive details about each KOI. Reconnaissance spectroscopy was used to refine the stellar and planet properties of each KOI at an early stage. SME spectral analysis and asteroseismology, when available, are used to obtain the final stellar properties. Adaptive Optics and speckle imaging constrain the presence of background eclipsing binaries that could masquerade as transiting planets. By combining ground based follow-up observations with Kepler photometry, a false positive probability is calculated for each KOI. An MCMC analysis that combines both Kepler photometry and Keck radial velocity measurements determines the final orbital parameters and planet properties for each system. The resulting mass vs. radius diagram for the planets reveals that radii increase with mass monotonically, well represented by a power law for the smallest planets. This M-R relationship offers key insights about the internal composition of the planets and the division between rocky and gaseous planets.

  11. Accretion of Jupiter-mass planets in the limit of vanishing viscosity

    SciTech Connect

    Szulágyi, J.; Morbidelli, A.; Crida, A.; Masset, F.

    2014-02-20

    In the core-accretion model, the nominal runaway gas-accretion phase brings most planets to multiple Jupiter masses. However, known giant planets are predominantly Jupiter mass bodies. Obtaining longer timescales for gas accretion may require using realistic equations of states, or accounting for the dynamics of the circumplanetary disk (CPD) in the low-viscosity regime, or both. Here we explore the second way by using global, three-dimensional isothermal hydrodynamical simulations with eight levels of nested grids around the planet. In our simulations, the vertical inflow from the circumstellar disk (CSD) to the CPD determines the shape of the CPD and its accretion rate. Even without a prescribed viscosity, Jupiter's mass-doubling time is ∼10{sup 4} yr, assuming the planet at 5.2 AU and a Minimum Mass Solar Nebula. However, we show that this high accretion rate is due to resolution-dependent numerical viscosity. Furthermore, we consider the scenario of a layered CSD, viscous only in its surface layer, and an inviscid CPD. We identify two planet-accretion mechanisms that are independent of the viscosity in the CPD: (1) the polar inflow—defined as a part of the vertical inflow with a centrifugal radius smaller than two Jupiter radii and (2) the torque exerted by the star on the CPD. In the limit of zero effective viscosity, these two mechanisms would produce an accretion rate 40 times smaller than in the simulation.

  12. On the width and shape of the corotation region for low-mass planets

    NASA Astrophysics Data System (ADS)

    Paardekooper, S.-J.; Papaloizou, J. C. B.

    2009-04-01

    We study the coorbital flow for embedded, low-mass planets. We provide a simple semi-analytic model for the corotation region, which is subsequently compared to high-resolution numerical simulations. The model is used to derive an expression for the half-width of the horseshoe region, xs, which in the limit of zero softening is given by xs/rp = 1.68(q/h)1/2, where q is the planet to central star mass ratio, h is the disc aspect ratio and rp is the orbital radius. This is in very good agreement with the same quantity measured from simulations. This result is used to show that horseshoe drag is about an order of magnitude larger than the linear corotation torque in the zero-softening limit. Thus, the horseshoe drag, the sign of which depends on the gradient of specific vorticity, is important for estimates of the total torque acting on the planet. We further show that phenomena, such as the Lindblad wakes, with a radial separation from corotation of approximately a pressure scaleheight H can affect xs, even though for low-mass planets xs << H. The effect is to distort streamlines and reduce xs through the action of a back pressure. This effect is reduced for smaller gravitational softening parameters and planets of higher mass, for which xs becomes comparable to H.

  13. Polarization of Directly Imaged Young Giant Planets as a Probe of Mass, Rotation, and Clouds

    NASA Technical Reports Server (NTRS)

    Marley, Mark Scott; Sengupta, Sujan

    2012-01-01

    Young, hot gas giant planets at large separations from their primaries have been directly imaged around several nearby stars. More such planets will likely be detected by ongoing and new imaging surveys with instruments such as the Gemini Planet Imager (GPI). Efforts continue to model the spectra of these planets in order to constrain their masses, effective temperatures, composition, and cloud structure. One potential tool for analyzing these objects, which has received relatively less attention, is polarization. Linear polarization of gas giant exoplanets can arise from the combined influences of light scattering by atmospheric dust and a rotationally distorted shape. The oblateness of gas giant planet increases of course with rotation rate and for fixed rotation also rises with decreasing gravity. Thus young, lower mass gas giant planets with youthful inflated radii could easily have oblateness greater than that of Saturn s 10%. We find that polarizations of over 1% may easily be produced in the near-infrared in such cases. This magnitude of polarization may be measurable by GPI and other instruments. Thus if detected, polarization of a young Jupiter places constraints on the combination of its gravity, rotation rate, and degree of cloudiness. We will present results of our multiple scattering analysis coupled with a self-consistent dusty atmospheric models to demonstrate the range of polarizations that might be expected from resolved exoplanets and the range of parameter space that such observations may inform.

  14. The Orbit and Mass of the Third Planet in the Kepler-56 System

    NASA Astrophysics Data System (ADS)

    Otor, Oderah Justin; Montet, Benjamin T.; Johnson, John Asher; Charbonneau, David; Collier-Cameron, Andrew; Howard, Andrew W.; Isaacson, Howard; Latham, David W.; Lopez-Morales, Mercedes; Lovis, Christophe; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Pepe, Francesco; Piotto, Giampaolo; Phillips, David F.; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Udry, Stéphane; Watson, Chris

    2016-12-01

    While the vast majority of multiple-planet systems have orbital angular momentum axes that align with the spin axis of their host star, Kepler-56 is an exception: its two transiting planets are coplanar yet misaligned by at least 40° with respect to the rotation axis of their host star. Additional follow-up observations of Kepler-56 suggest the presence of a massive, non-transiting companion that may help explain this misalignment. We model the transit data along with Keck/HIRES and HARPS-N radial velocity data to update the masses of the two transiting planets and infer the physical properties of the third, non-transiting planet. We employ a Markov Chain Monte Carlo sampler to calculate the best-fitting orbital parameters and their uncertainties for each planet. We find the outer planet has a period of 1002 ± 5 days and minimum mass of 5.61 ± 0.38 {M}{Jup}. We also place a 95% upper limit of 0.80 m s-1 yr-1 on long-term trends caused by additional, more distant companions.

  15. What Debris Disks Can Tell Us about the Masses, Orbits, and Compositions of Planets

    NASA Astrophysics Data System (ADS)

    Rodigas, T.

    2014-09-01

    Our solar system contains four gas giant planets that have interacted and shaped the Kuiper Belt since their formation. They have affected its structure and shape and in the process have flung comets and small rocky bodies towards the inner terrestrial planets. Many of these bodies contain organic materials and water ice, the main ingredients required for Earth-like life. Therefore the Kuiper Belt holds clues to the properties of the solar system's planets. In the same way, it is thought that extrasolar debris disks, analogous to the solar system's Kuiper Belt, contain information on nearby planets. In this talk, I will discuss several recent results that relate the properties of debris disks to masses, orbits, and compositions of as-yet undetected planets. First, I will present 3.8 micron LBTI high-contrast adaptive optics (AO) imaging on the bright, edge-on debris disk around HD 32297 (Rodigas et al. 2014b). Combing our high signal-to-noise (S/N) detection with archival images at 1-2 microns, we constrain the composition of the dust grains in the disk. In particular, we test a recently proposed cometary grains model. We find that pure water ice is a better overall fit, suggesting at least one of the key ingredients for life may be present in this system. Second, I will present Magellan AO (MagAO) imaging results on the debris ring around HR 4796A at seven wavelengths from 0.7-4 microns (Rodigas et al. 2014c, in prep.). With such complete wavelength coverage and high S/N detections, we are able to obtain accurate photometry and constrain the composition of the dustÑin particular with regard to organic materials. Finally, I will present a new tool designed specifically for observers and planet hunters. Using a simple equation that depends solely on the width of a debris disk in scattered light, observers can estimate the maximum mass of an interior planet shepherding the disk (Rodigas et al. 2014a). This provides an independent, dynamical check on an imaged planet

  16. Terrestrial Planet Formation: Dynamical Shake-up and the Low Mass of Mars

    NASA Astrophysics Data System (ADS)

    Bromley, Benjamin C.; Kenyon, Scott J.

    2017-05-01

    We consider a dynamical shake-up model to explain the low mass of Mars and the lack of planets in the asteroid belt. In our scenario, a secular resonance with Jupiter sweeps through the inner solar system as the solar nebula depletes, pitting resonant excitation against collisional damping in the Sun’s protoplanetary disk. We report the outcome of extensive numerical calculations of planet formation from planetesimals in the terrestrial zone, with and without dynamical shake-up. If the Sun’s gas disk within the terrestrial zone depletes in roughly a million years, then the sweeping resonance inhibits planet formation in the asteroid belt and substantially limits the size of Mars. This phenomenon likely occurs around other stars with long-period massive planets, suggesting that asteroid belt analogs are common.

  17. Characterising the atmosphere of a uniquely low-density, sub-Saturn mass planet

    NASA Astrophysics Data System (ADS)

    Spake, Jessica; Anderson, D.; Barstow, J.; Evans, T.; Gillon, M.; Hebrardr, G.; Hellier, C.; Kataria, T.; Lam, K.; Nikolov, N.; Sing, D.; Triaud, A.; Wakeford, H.

    2016-08-01

    We propose to use HST and Spitzer to measure the transmission spectrum of the recently discovered, hot sub-Saturn mass exoplanet WASP-127b. Its low mass (0.19 Mj) and large radius (1.39 Rj) give it the lowest density of any exoplanet with a radial velocity measured mass. It has the largest predicted atmospheric scale height of any planet, and orbits a bright (V~10.2) star, making it an exceptional target for atmospheric characterisation via transmission spectroscopy. With HST and Spitzer, we will measure the full transmission spectrum from 0.3 to 5 microns, covering water, sodium, and potassium absorption features, and scattering by molecular hydrogen or haze. The Spitzer transit photometry at 3.6 and 4.5 microns will be used alongside the HST spectrum to break the low abundance/cloud degeneracy which prevents constraints being made on atmospheric metallicity. With a low mass of 0.19 Mj, this planet sits in an unexplored mass range at the very low-end of gas giant planets, making WASP-127b strategecally important for constraining the planetary mass-metallicity relationship, which is important for understanding planet formation mechanisms.

  18. KEPLER-20: A SUN-LIKE STAR WITH THREE SUB-NEPTUNE EXOPLANETS AND TWO EARTH-SIZE CANDIDATES

    SciTech Connect

    Gautier, Thomas N. III; Rowe, Jason F.; Bryson, Stephen T.; Marcy, Geoffrey W.; Isaacson, Howard; Rogers, Leslie A.; Buchhave, Lars A.; Ciardi, David R.; Ford, Eric B.; Gilliland, Ronald L.; Walkowicz, Lucianne M.; Cochran, William D.; Endl, Michael; and others

    2012-04-10

    We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASS J19104752+4220194. From high-resolution spectroscopy of the star, we find a stellar effective temperature T{sub eff} = 5455 {+-} 100 K, a metallicity of [Fe/H] = 0.01 {+-} 0.04, and a surface gravity of log g = 4.4 {+-} 0.1. We combine these estimates with an estimate of the stellar density derived from the transit light curves to deduce a stellar mass of M{sub *} = 0.912 {+-} 0.034 M{sub Sun} and a stellar radius of R{sub *} = 0.944{sup +0.060}{sub -0.095} R{sub Sun }. For three of the transit signals, we demonstrate that our results strongly disfavor the possibility that these result from astrophysical false positives. We accomplish this by first identifying the subset of stellar blends that reproduce the precise shape of the light curve and then using the constraints on the presence of additional stars from high angular resolution imaging, photometric colors, and the absence of a secondary component in our spectroscopic observations. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2 Multiplication-Sign 10{sup 5} (Kepler-20b), 1 Multiplication-Sign 10{sup 5} (Kepler-20c), and 1.1 Multiplication-Sign 10{sup 3} (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: from Spitzer data gathered at 4.5 {mu}m, we infer a ratio of the planetary to stellar radii of 0.075 {+-} 0.015 (Kepler-20c) and 0.065 {+-} 0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70 days and 1.91{sup +0.12}{sub -0.21} R{sub Circled-Plus} for Kepler-20b, 10

  19. Search for the transit of a nearby 2 Earth-mass planet

    NASA Astrophysics Data System (ADS)

    Gillon, Michael; Affer, Laura; Bonomo, Aldo; Damasso, Mario; Desidera, Silvano; Micela, Giuseppina; Rebolo, Rafael; Ribas, Ignasi; Sozzetti, Alessandro

    2016-08-01

    The frontier of exoplanetology is being pushed to the identification of Earth-sized exoplanets well-suited for detailed characterization with future observatories, notably with JWST. Transit searches targeting nearby M-dwarfs are at the forefront of this effort. Indeed, the favorable planet-star contrast ratios of M-dwarfs enable the best opportunities in the near-future for detailed characterization studies of transiting terrestrial planets and their atmospheres. In this context, we propose here to use the exquisite photometric precision of Spitzer to search for the transit of a new short-period (2.6d) very-low-mass (2 Earth-mass) super-Earth that we have just detected with the HARPS-N spectrograph. This planet orbits at <0.03 au of a nearby (18pc) M1-type dwarf, resulting in a transit probability of 8%. A transit detection would make possible to discriminate metal-rich, silicate rich, and ice-rich planetary compositions, and to test further the hypothesis that the population of dense, close-in planets of 1-6 Earth-mass can be described by a fixed Earth-like compositional model. Furthermore, it would make the planet join the handful of super-Earths well-suited for detailed atmospheric characterization with JWST, thanks to the infrared brightness (K=6.8) and the small size (0.5 solar radius) of its M-dwarf host star.

  20. A Neptune-Mass Planet Orbiting the Nearby M Dwarf GJ 436

    NASA Astrophysics Data System (ADS)

    Butler, R. Paul; Vogt, Steven S.; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Laughlin, Greg; Lissauer, Jack J.

    2004-12-01

    We report precise Doppler measurements of GJ 436 (M2.5 V) obtained at Keck Observatory. The velocities reveal a planetary companion with orbital period of 2.644 days, eccentricity of 0.12 (consistent with zero), and velocity semiamplitude of K=18.1 m s-1. The minimum mass (Msini) for the planet is 0.067MJup=1.2MNep=21MEarth, making it the lowest mass exoplanet yet found around a main-sequence star and the first candidate in the Neptune-mass domain. GJ 436 (mass = 0.41 Msolar) is only the second M dwarf found to harbor a planet, joining the two-planet system around GJ 876. The low mass of the planet raises questions about its constitution, with possible compositions of primarily H and He gas, ice/rock, or rock-dominated. The implied semimajor axis is a=0.028AU=14 stellar radii, raising issues of planet formation, migration, and tidal coupling with the star. GJ 436 is more than 3 Gyr old, based on both kinematic and chromospheric diagnostics. The star exhibits no photometric variability on the 2.644 day Doppler period to a limiting amplitude of 0.0004 mag, supporting the planetary interpretation of the Doppler periodicity. Photometric transits of the planet across the star are ruled out for gas giant compositions and are also unlikely for solid compositions. As the third closest known planetary system, GJ 436 warrants follow-up observations by high-resolution optical and infrared imaging and by the Space Interferometry Mission. 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. Keck time has been granted by both NASA and the University of California.

  1. There might be giants: unseen Jupiter-mass planets as sculptors of tightly packed planetary systems

    NASA Astrophysics Data System (ADS)

    Hands, T. O.; Alexander, R. D.

    2016-03-01

    The limited completeness of the Kepler sample for planets with orbital periods ≳1 yr leaves open the possibility that exoplanetary systems may host undetected giant planets. Should such planets exist, their dynamical interactions with the inner planets may prove vital in sculpting the final orbital configurations of these systems. Using an N-body code with additional forces to emulate the effects of a protoplanetary disc, we perform simulations of the assembly of compact systems of super-Earth-mass planets with unseen giant companions. The simulated systems are analogous to Kepler-11 or Kepler-32 in that they contain four or five inner super-Earths, but our systems also contain longer-period giant companions which are unlikely to have been detected by Kepler. We find that giant companions tend to break widely spaced first-order mean-motion resonances, allowing the inner planets to migrate into tighter resonances. This leads to more compact architectures and increases the occurrence rate of Laplace resonant chains.

  2. Characterization of Low-mass K2 planet hosts using Near-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodríguez-Martínez, Romy; Ballard, Sarah

    2017-01-01

    The raw number of discovered exoplanets now exceeds several thousand, but we must understand the stars if we aim to understand their planets in detail. Of particular interest are M dwarf stars, which are often favored for exoplanet study because (1) they host small planets in greatest abundance, (2) they make up about 70% of stars in our galaxy, and (3) the planets that orbit them that are comparatively easier to find and study than planets around larger stars. Our work aims to characterize the infrared spectra of 50 M dwarfs with new and unstudied transiting planets discovered by NASA’s K2 Mission. We employ empirical relations from the literature with magnesium, aluminum and sodium absorption lines in H and K band to determine the temperatures, radii and luminosities. In addition, we measure the deformation of the spectra in K band by water (another empirical metric for M dwarfs) which, in tandem with absorption features, is linked to [Fe/H] metallicity. We have found from a preliminary sample of 36 stars, that the temperatures range from 2,900 to 4,100 K, with radii between 0.2 R⊙ to 0.6R⊙ and log(L/L⊙) values from -3.4 to -0.5. The determination of all these properties improves our understanding of the planet’s properties, such as its size, mass, and surface temperature, and provides clues about the formation of the star and its planets.

  3. Evolutionary Tracks of the Climate of Earth-like Planets around Different Mass Stars

    NASA Astrophysics Data System (ADS)

    Kadoya, S.; Tajika, E.

    2016-07-01

    The climatic evolution of the Earth depends strongly on the evolution of the insolation from the Sun and the amount of the greenhouse gasses, especially CO2 in the atmosphere. Here, we investigate the evolution of the climate of hypothetical Earths around stars whose masses are different from the solar mass with a luminosity evolution model of the stars, a mantle degassing model coupled with a parameterized convection model of the planetary interiors, and an energy balance climate model of the planetary surface. In the habitable zone (HZ), the climate of the planets is initially warm or hot, depending on the orbital semimajor axes. We found that, in the inner HZ, the climate of the planets becomes hotter with time owing to the increase in the luminosity of the central stars, while, in the outer HZ, it becomes colder and eventually globally ice-covered owing to the decrease in the CO2 degassing rate of the planets. The orbital condition for maintaining the warm climate similar to the present Earth becomes very limited, and more interestingly, the planet orbiting in the outer HZ becomes globally ice-covered after a certain critical age (˜3 Gyr for the hypothetical Earth with standard parameters), irrespective of the mass of the central star. This is because the critical age depends on the evolution of the planets and planetary factors, rather than on the stellar mass. The habitability of the Earth-like planet is shown to be limited with age even though it is orbiting within the HZ.

  4. MASSIVE: A Bayesian analysis of giant planet populations around low-mass stars

    NASA Astrophysics Data System (ADS)

    Lannier, J.; Delorme, P.; Lagrange, A. M.; Borgniet, S.; Rameau, J.; Schlieder, J. E.; Gagné, J.; Bonavita, M. A.; Malo, L.; Chauvin, G.; Bonnefoy, M.; Girard, J. H.

    2016-12-01

    Context. Direct imaging has led to the discovery of several giant planet and brown dwarf companions. These imaged companions populate a mass, separation and age domain (mass >1 MJup, orbits > 5 AU, age < 1 Gyr) quite distinct from the one occupied by exoplanets discovered by the radial velocity or transit methods. This distinction could indicate that different formation mechanisms are at play. Aims: We aim at investigating correlations between the host star's mass and the presence of wide-orbit giant planets, and at providing new observational constraints on planetary formation models. Methods: We observed 58 young and nearby M-type dwarfs in L'-band with the VLT/NaCo instrument and used angular differential imaging algorithms to optimize the sensitivity to planetary-mass companions and to derive the best detection limits. We estimate the probability of detecting a planet as a function of its mass and physical separation around each target. We conduct a Bayesian analysis to determine the frequency of substellar companions orbiting low-mass stars, using a homogenous sub-sample of 54 stars. Results: We derive a frequency of for companions with masses in the range of 2-80 MJup, and % for planetary mass companions (2-14 MJup), at physical separations of 8 to 400 AU for both cases. Comparing our results with a previous survey targeting more massive stars, we find evidence that substellar companions more massive than 1 MJup with a low mass ratio Q with respect to their host star (Q < 1%), are less frequent around low-mass stars. This may represent observational evidence that the frequency of imaged wide-orbit substellar companions is correlated with stellar mass, corroborating theoretical expectations. Contrarily, we show statistical evidence that intermediate-mass ratio (1% < Q < 5%) companion with masses >2 MJup might be independent from the mass of the host star.

  5. Interior phase transformations and mass-radius relationships of silicon-carbon planets

    SciTech Connect

    Wilson, Hugh F.; Militzer, Burkhard

    2014-09-20

    Planets such as 55 Cancri e orbiting stars with a high carbon-to-oxygen ratio may consist primarily of silicon and carbon, with successive layers of carbon, silicon carbide, and iron. The behavior of silicon-carbon materials at the extreme pressures prevalent in planetary interiors, however, has not yet been sufficiently understood. In this work, we use simulations based on density functional theory to determine high-pressure phase transitions in the silicon-carbon system, including the prediction of new stable compounds with Si{sub 2}C and SiC{sub 2} stoichiometry at high pressures. We compute equations of state for these silicon-carbon compounds as a function of pressure, and hence derive interior structural models and mass-radius relationships for planets composed of silicon and carbon. Notably, we predict a substantially smaller radius for SiC planets than in previous models, and find that mass radius relationships for SiC planets are indistinguishable from those of silicate planets. We also compute a new equation of state for iron. We rederive interior models for 55 Cancri e and are able to place more stringent restrictions on its composition.

  6. Interior Phase Transformations and Mass-Radius Relationships of Silicon-Carbon Planets

    NASA Astrophysics Data System (ADS)

    Wilson, Hugh F.; Militzer, Burkhard

    2014-09-01

    Planets such as 55 Cancri e orbiting stars with a high carbon-to-oxygen ratio may consist primarily of silicon and carbon, with successive layers of carbon, silicon carbide, and iron. The behavior of silicon-carbon materials at the extreme pressures prevalent in planetary interiors, however, has not yet been sufficiently understood. In this work, we use simulations based on density functional theory to determine high-pressure phase transitions in the silicon-carbon system, including the prediction of new stable compounds with Si2C and SiC2 stoichiometry at high pressures. We compute equations of state for these silicon-carbon compounds as a function of pressure, and hence derive interior structural models and mass-radius relationships for planets composed of silicon and carbon. Notably, we predict a substantially smaller radius for SiC planets than in previous models, and find that mass radius relationships for SiC planets are indistinguishable from those of silicate planets. We also compute a new equation of state for iron. We rederive interior models for 55 Cancri e and are able to place more stringent restrictions on its composition.

  7. The Lick Planet Search: Detectability and Mass Thresholds

    NASA Astrophysics Data System (ADS)

    Cumming, Andrew; Marcy, Geoffrey W.; Butler, R. Paul

    1999-12-01

    We present an analysis of 11 yr of precision radial velocity measurements of 76 nearby solar-type stars from the Lick radial velocity survey. For each star, we report on variability, periodicity, and long-term velocity trends. Our sample of stars contains eight known companions with mass (Mpsini) less than 8 Jupiter masses (MJ), six of which were discovered at Lick. For the remaining stars, we place upper limits on the companion mass as a function of orbital period. For most stars, we can exclude companions with velocity amplitude K>~20 m s-1 at the 99% level, or Mpsini>~0.7MJ(a/AU)1/2 for orbital radii a<~5 AU. We examine the implications of our results for the observed distribution of mass and orbital radius of companions. We show that the combination of intrinsic stellar variability and measurement errors most likely explains why all confirmed companions so far have K>~40 m s-1. The finite duration of the observations limits detection of Jupiter-mass companions to a<~3 AU. Thus it remains possible that the majority of solar-type stars harbor Jupiter-mass companions much like our own, and if so these companions should be detectable in a few years. It is striking that more massive companions with Mpsini>3MJ are rare at orbital radii 4-6 AU; we could have detected such objects in ~90% of stars, yet found none. The observed companions show a ``piling-up'' toward small orbital radii, and there is a paucity of confirmed and candidate companions with orbital radii between ~0.2 and ~1 AU. The small number of confirmed companions means that we are not able to rule out selection effects as the cause of these features. We show that the traditional method for detecting periodicities, the Lomb-Scargle periodogram, fails to account for statistical fluctuations in the mean of a sampled sinusoid, making it nonrobust when the number of observations is small, the sampling is uneven, or for periods comparable to or greater than the duration of the observations. We adopt a

  8. Constraining the mass of the planet(s) sculpting a disk cavity. The intriguing case of 2MASS J16042165-2130284

    NASA Astrophysics Data System (ADS)

    Canovas, H.; Hardy, A.; Zurlo, A.; Wahhaj, Z.; Schreiber, M. R.; Vigan, A.; Villaver, E.; Olofsson, J.; Meeus, G.; Ménard, F.; Caceres, C.; Cieza, L. A.; Garufi, A.

    2017-02-01

    Context. The large cavities observed in the dust and gas distributions of transition disks may be explained by planet-disk interactions. At 145 pc, 2MASS J16042165-2130284 (J1604) is a 5-12 Myr old transitional disk with different gap sizes in the mm- and μm-sized dust distributions (outer edges at 79 and at 63 au, respectively). Its 12CO emission shows a 30 au cavity. This radial structure suggests that giant planets are sculpting this disk. Aims: We aim to constrain the masses and locations of plausible giant planets around J1604. Methods: We observed J1604 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) at the Very Large Telescope (VLT), in IRDIFS_EXT, pupil-stabilized mode, obtaining YJH-band images with the integral field spectrograph (IFS) and K1K2-band images with the Infra-Red Dual-beam Imager and Spectrograph (IRDIS). The dataset was processed exploiting the angular differential imaging (ADI) technique with high-contrast algorithms. Results: Our observations reach a contrast of ΔK,ΔYH 12 mag from 0".15 to 0".80 ( 22 to 115 au), but no planet candidate is detected. The disk is directly imaged in scattered light at all bands from Y to K, and it shows a red color. This indicates that the dust particles in the disk surface are mainly ≳0.3 μm-sized grains. We confirm the sharp dip/decrement in scattered light in agreement with polarized light observations. Comparing our images with a radiative transfer model we argue that the southern side of the disk is most likely the nearest. Conclusions: This work represents the deepest search yet for companions around J1604. We reach a mass sensitivity of ≳2-3 MJup from 22 to 115 au according to a hot start scenario. We propose that a brown dwarf orbiting inside of 15 au and additional Jovian planets at larger radii could account for the observed properties of J1604 while explaining our lack of detection. Based on observations made with the VLT, program 095.C-0673(A).The reduced images (FITS

  9. MIGRATION THEN ASSEMBLY: FORMATION OF NEPTUNE-MASS PLANETS INSIDE 1 AU

    SciTech Connect

    Hansen, Brad M. S.; Murray, Norm

    2012-06-01

    We demonstrate that the observed distribution of 'hot Neptune'/'super-Earth' systems is well reproduced by a model in which planet assembly occurs in situ, with no significant migration post-assembly. This is achieved only if the amount of mass in rocky material is {approx}50-100 M{sub Circled-Plus} interior to 1 AU. Such a reservoir of material implies that significant radial migration of solid material takes place, and that it occurs before the stage of final planet assembly. The model not only reproduces the general distribution of mass versus period but also the detailed statistics of multiple planet systems in the sample. We furthermore demonstrate that cores of this size are also likely to meet the criterion to gravitationally capture gas from the nebula, although accretion is rapidly limited by the opening of gaps in the gas disk. If the mass growth is limited by this tidal truncation, then the scenario sketched here naturally produces Neptune-mass objects with substantial components of both rock and gas, as is observed. The quantitative expectations of this scenario are that most planets in the 'hot Neptune/super-Earth' class inhabit multiple-planet systems, with characteristic orbital spacings. The model also provides a natural division into gas-rich (hot Neptune) and gas-poor (super-Earth) classes at fixed period. The dividing mass ranges from {approx}3 M{sub Circled-Plus} at 10 day orbital periods to {approx}10 M{sub Circled-Plus} at 100 day orbital periods. For orbital periods <10 days, the division is less clear because a gas atmosphere may be significantly eroded by stellar radiation.

  10. Fomalhaut's Debris Disk and Planet: Constraining the Mass of Formalhaut B from Disk Morphology

    NASA Technical Reports Server (NTRS)

    Chiang, E.; Kite, E.; Kalas, P.; Graham, J. R.; Clampin, M.

    2008-01-01

    Following the optical imaging of exoplanet candidate Fomalhaut b (Fom b), we present a numerical model of how Fomalhaut's debris disk is gravitationally shaped by a single interior planet. The model is simple, adaptable to other debris disks, and can be extended to accommodate multiple planets. If Fom b is the dominant perturber of the belt, then to produce the observed disk morphology it must have a mass M(sub pl) < 3M(sub J), an orbital semimajor axis a(sub pl) > 101.5AU, and an orbital eccentricity e(sub pl) = 0.11 - 0.13. These conclusions are independent of Fom b's photometry. To not disrupt the disk, a greater mass for Fom b demands a smaller orbit farther removed from the disk; thus, future astrometric measurement of Fom b's orbit, combined with our model of planet-disk interaction, can be used to determine the mass more precisely. The inner edge of the debris disk at a approximately equals 133AU lies at the periphery of Fom b's chaotic zone, and the mean disk eccentricity of e approximately equals 0.11 is secularly forced by the planet, supporting predictions made prior to the discovery of Fom b. However, previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our constraint is more reliable. It is based on a global model of the disk that is not restricted to the planet's chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical stability over the system age of approximately 100 Myr, and model them separately from their dust grain progeny; the latter's orbits are strongly affected by radiation pressure and their lifetimes are limited to approximately 0.1 Myr by destructive grain-grain collisions. The single planet model predicts that planet and disk orbits be apsidally aligned. Fomalhaut b's nominal space velocity does not bear this out, but the astrometric uncertainties are difficult to quantify. Even if the apsidal misalignment proves real, our calculated upper mass limit of 3 M(sub J) still

  11. Fomalhaut's Debris Disk and Planet: Constraining the Mass of Fomalhaut b from disk Morphology

    NASA Astrophysics Data System (ADS)

    Chiang, E.; Kite, E.; Kalas, P.; Graham, J. R.; Clampin, M.

    2009-03-01

    Following the optical imaging of exoplanet candidate Fomalhaut b (Fom b), we present a numerical model of how Fomalhaut's debris disk is gravitationally shaped by a single interior planet. The model is simple, adaptable to other debris disks, and can be extended to accommodate multiple planets. If Fom b is the dominant perturber of the belt, then to produce the observed disk morphology it must have a mass M pl < 3M J, an orbital semimajor axis a pl > 101.5 AU, and an orbital eccentricity e pl = 0.11-0.13. These conclusions are independent of Fom b's photometry. To not disrupt the disk, a greater mass for Fom b demands a smaller orbit farther removed from the disk; thus, future astrometric measurement of Fom b's orbit, combined with our model of planet-disk interaction, can be used to determine the mass more precisely. The inner edge of the debris disk at a ≈ 133 AU lies at the periphery of Fom b's chaotic zone, and the mean disk eccentricity of e ≈ 0.11 is secularly forced by the planet, supporting predictions made prior to the discovery of Fom b. However, previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our constraint is more reliable. It is based on a global model of the disk that is not restricted to the planet's chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical stability over the system age of ~ 100 Myr, and model them separately from their dust grain progeny; the latter's orbits are strongly affected by radiation pressure and their lifetimes are limited to ~ 0.1 Myr by destructive grain-grain collisions. The single planet model predicts that planet and disk orbits be apsidally aligned. Fomalhaut b's nominal space velocity does not bear this out, but the astrometric uncertainties may be large. If the apsidal misalignment proves real, our calculated upper mass limit of 3M J still holds. If the orbits are aligned, our model predicts M pl = 0.5M J, a pl = 115 AU, and e pl = 0

  12. Extreme Planet-Like Systems: Brown Dwarfs at the Exoplanet Mass Boundary

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline Kelly

    2015-12-01

    Brown dwarfs have long been the observational anchors for our theoretical understanding of giant gas planets. Recent studies have uncovered a population of nearby young sources that rival the age and mass of many planetary mass companions. From detailed observations, we postulate that objects in this young population have dynamic atmospheres ripe with exotic, thick condensate cloud species that drive extreme photometric and spectroscopic characteristics. In this talk I will review how we are using these so-called exoplanet analogs to establish luminosity, temperature, age, and mass relations for brown dwarf into planetary mass objects.

  13. The HARPS search for southern extra-solar planets. XLII. A system of Earth-mass planets around the nearby M dwarf YZ Ceti

    NASA Astrophysics Data System (ADS)

    Astudillo-Defru, N.; Díaz, R. F.; Bonfils, X.; Almenara, J. M.; Delisle, J.-B.; Bouchy, F.; Delfosse, X.; Forveille, T.; Lovis, C.; Mayor, M.; Murgas, F.; Pepe, F.; Santos, N. C.; Ségransan, D.; Udry, S.; Wünsche, A.

    2017-09-01

    Exoplanet surveys have shown that systems with multiple low-mass planets on compact orbits are common. Except for a few cases, however, the masses of these planets are generally unknown. At the very end of the main sequence, host stars have the lowest mass and hence offer the largest reflect motion for a given planet. In this context, we monitored the low-mass (0.13 M⊙) M dwarf YZ Cet (GJ 54.1, HIP 5643) intensively and obtained radial velocities and stellar-activity indicators derived from spectroscopy and photometry, respectively. We find strong evidence that it is orbited by at least three planets in compact orbits (POrb = 1.97, 3.06, 4.66 days), with the inner two near a 2:3 mean-motion resonance. The minimum masses are comparable to the mass of Earth (M sin i = 0.75 ± 0.13, 0.98 ± 0.14, and 1.14 ± 0.17 M⊕), and they are also the lowest masses measured by radial velocity so far. We note the possibility for a fourth planet with an even lower mass of M sin i = 0.472 ± 0.096 M⊕ at POrb = 1.04 days. An n-body dynamical model is used to place further constraints on the system parameters. At 3.6 parsecs, YZ Cet is the nearest multi-planet system detected to date. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 180.C-0886(A), 183.C-0437(A), and 191.C-0873(A) at Cerro La Silla (Chile).Radial velocity data (Table B.4) 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/605/L11

  14. XUV-driven mass loss from extrasolar giant planets orbiting active stars

    NASA Astrophysics Data System (ADS)

    Chadney, J. M.; Galand, M.; Unruh, Y. C.; Koskinen, T. T.; Sanz-Forcada, J.

    2015-04-01

    Upper atmospheres of Hot Jupiters are subject to extreme radiation conditions that can result in rapid atmospheric escape. The composition and structure of the upper atmospheres of these planets are affected by the high-energy spectrum of the host star. This emission depends on stellar type and age, which are thus important factors in understanding the behaviour of exoplanetary atmospheres. In this study, we focus on Extrasolar Giant Planets (EPGs) orbiting K and M dwarf stars. XUV spectra for three different stars - ɛ Eridani, AD Leonis and AU Microscopii - are constructed using a coronal model. Neutral density and temperature profiles in the upper atmosphere of hypothetical EGPs orbiting these stars are then obtained from a fluid model, incorporating atmospheric chemistry and taking atmospheric escape into account. We find that a simple scaling based solely on the host star's X-ray emission gives large errors in mass loss rates from planetary atmospheres and so we have derived a new method to scale the EUV regions of the solar spectrum based upon stellar X-ray emission. This new method produces an outcome in terms of the planet's neutral upper atmosphere very similar to that obtained using a detailed coronal model of the host star. Our results indicate that in planets subjected to radiation from active stars, the transition from Jeans escape to a regime of hydrodynamic escape at the top of the atmosphere occurs at larger orbital distances than for planets around low activity stars (such as the Sun).

  15. The SOPHIE search for northern extrasolar planets. XII. Three giant planets suitable for astrometric mass determination with Gaia

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    We present new radial velocity measurements for three low-metallicity solar-like stars observed with the SOPHIE spectrograph and its predecessor ELODIE, both installed at the 193 cm telescope of the Haute-Provence Observatory, allowing the detection and characterization of three new giant extrasolar planets in intermediate periods of 1.7 to 3.7 yr. All three stars, HD 17674, HD 42012 and HD 29021 present single giant planetary companions with minimum masses between 0.9 and 2.5 MJup. The range of periods and masses of these companions, along with the distance of their host stars, make them good targets to look for astrometric signals over the lifetime of the new astrometry satellite Gaia. We discuss the preliminary astrometric solutions obtained from the first Gaia data release. 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.Tables 5-7 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A9

  16. On the minimum core mass for giant planet formation at wide separations

    SciTech Connect

    Piso, Ana-Maria A.; Youdin, Andrew N.

    2014-05-01

    In the core accretion hypothesis, giant planets form by gas accretion onto solid protoplanetary cores. The minimum (or critical) core mass to form a gas giant is typically quoted as 10 M {sub ⊕}. The actual value depends on several factors: the location in the protoplanetary disk, atmospheric opacity, and the accretion rate of solids. Motivated by ongoing direct imaging searches for giant planets, this study investigates core mass requirements in the outer disk. To determine the fastest allowed rates of gas accretion, we consider solid cores that no longer accrete planetesimals, as this would heat the gaseous envelope. Our spherical, two-layer atmospheric cooling model includes an inner convective region and an outer radiative zone that matches onto the disk. We determine the minimum core mass for a giant planet to form within a typical disk lifetime of 3 Myr. The minimum core mass declines with disk radius, from ∼8.5 M {sub ⊕} at 5 AU to ∼3.5 M {sub ⊕} at 100 AU, with standard interstellar grain opacities. Lower temperatures in the outer disk explain this trend, while variations in disk density are less influential. At all distances, a lower dust opacity or higher mean molecular weight reduces the critical core mass. Our non-self-gravitating, analytic cooling model reveals that self-gravity significantly affects early atmospheric evolution, starting when the atmosphere is only ∼10% as massive as the core.

  17. 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

  18. 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

  19. VOLATILE DELIVERY TO PLANETS FROM WATER-RICH PLANETESIMALS AROUND LOW-MASS STARS

    SciTech Connect

    Ciesla, Fred J.; Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

    2015-05-01

    Most models of volatile delivery to accreting terrestrial planets assume that the carriers for water are similar in water content to the carbonaceous chondrites in our solar system. Here we consider how the water content of planetesimals may be higher in many planetary systems, as they could lack the short-lived radionuclides that drove water loss in carbonaceous chondrites in our solar system. Using N-body simulations, we explore how planetary accretion would be different if bodies beyond the water line contained a water-mass fraction consistent with chemical equilibrium calculations, and more similar to comets, as opposed to the more traditional water-depleted values. We apply this model to consider planet formation around stars of different masses and identify trends in the properties of habitable zone planets and planetary system architecture that could be tested by ongoing exoplanet census data collection. Comparison of such data with the model-predicted trends will serve to evaluate how well the N-body simulations and the initial conditions used in studies of planetary accretion can be used to understand this stage of planet formation.

  20. Volatile Delivery to Planets from Water-rich Planetesimals around Low Mass Stars

    NASA Astrophysics Data System (ADS)

    Ciesla, Fred J.; Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

    2015-05-01

    Most models of volatile delivery to accreting terrestrial planets assume that the carriers for water are similar in water content to the carbonaceous chondrites in our solar system. Here we consider how the water content of planetesimals may be higher in many planetary systems, as they could lack the short-lived radionuclides that drove water loss in carbonaceous chondrites in our solar system. Using N-body simulations, we explore how planetary accretion would be different if bodies beyond the water line contained a water-mass fraction consistent with chemical equilibrium calculations, and more similar to comets, as opposed to the more traditional water-depleted values. We apply this model to consider planet formation around stars of different masses and identify trends in the properties of habitable zone planets and planetary system architecture that could be tested by ongoing exoplanet census data collection. Comparison of such data with the model-predicted trends will serve to evaluate how well the N-body simulations and the initial conditions used in studies of planetary accretion can be used to understand this stage of planet formation.

  1. Surfing the photon noise: New techniques to find low-mass planets around M dwarfs

    NASA Astrophysics Data System (ADS)

    Anglada-Escudé, G.; Butler, R. P.; Reiners, A.; Jones, H. R. A.; Tuomi, M.; Jenkins, J. S.; Barnes, J. R.; Vogt, S. S.; Zechmeister, M.

    2013-02-01

    The current precision radial velocities techniques to detect low mass planets in M dwarf are quickly reviewed. This includes high resolution spectroscopic observations made both in the optical and in the near infrared. We discuss that, given the current instrumental performance, optical RVs are still far ahead over other approaches. However, this situation might change soon with the advent of new spectrographs with red/nIR capabilities. We review a newly developed method to obtain precision RV measurements on stabilized spectrographs and how it is implemented to archival HARPS observations. In addition to get much closer to the photon noise, this approach allows us to identify and filter out wavelength dependent noise sources achieving unprecedented accuracy on G, K and specially M dwarfs. We show how including red/infrared observations is of paramount importance to efficiently and unambiguously detect very low mass planets around cool spectral types. As examples, we show new measurements on Barnard's star indicating that the star is stable down to 0.9 cm s^-1 over a time-span of 4 years and how RV signals correlated with activity indices disappear when using the reddest half of the HARPS wavelength range. To conclude, we present new results, detections and describe the implications in terms of planet/multi-planet abundances around cool stars.

  2. 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.

  3. Generation of inclined protoplanetary discs and misaligned planets through mass accretion - I. Coplanar secondary discs

    NASA Astrophysics Data System (ADS)

    Xiang-Gruess, M.; Kroupa, P.

    2017-10-01

    We study the three-dimensional (3D) evolution of a viscous protoplanetary disc that accretes gas material from a second protoplanetary disc during a close encounter in an embedded star cluster. The aim is to investigate the capability of the mass accretion scenario to generate strongly inclined gaseous discs that could later form misaligned planets. We use smoothed particle hydrodynamics to study mass transfer and disc inclination for passing stars and circumstellar discs with different masses. We explore different orbital configurations to find the parameter space that allows significant disc inclination generation. Thies et al. suggested that significant disc inclination and disc or planetary system shrinkage can generally be produced by the accretion of external gas material with a different angular momentum. We found that this condition can be fulfilled for a large range of gas mass and angular momentum. For all encounters, mass accretion from the secondary disc increases with decreasing mass of the secondary proto-star. Thus, higher disc inclinations can be attained for lower secondary stellar masses. Variations of the secondary disc's orientation relative to the orbital plane can alter the disc evolution significantly. The results taken together show that mass accretion can change the 3D disc orientation significantly resulting in strongly inclined discs. In combination with the gravitational interaction between the two star-disc systems, this scenario is relevant for explaining the formation of highly inclined discs that could later form misaligned planets.

  4. Post-RGB Stars With Planets And Mass Loss On The RGB.

    NASA Astrophysics Data System (ADS)

    Willson, Lee Anne M.; Struck, C.; Wang, Q.; Marasinghe, K.

    2009-01-01

    Recent observations of mass loss from a fraction of the stars along the RGB in 47 Tuc are at odds with our understanding of single-star mechanisms for mass loss as these kick in only at or above the tip of the RGB. The observations are well fitted by mass loss rates matched to the evolutionary time scale for the stars (dlnM/dt ≈ dlnR/dt), suggesting a negative-feedback mass loss mechanism depending on the red giant radius. One possibility for such a mechanism is the effect of a jovian-mass planet orbiting near the surface of the red giant; if this drives mass loss then negative feedback is likely for sufficiently large planetary compations. The positive feedback maintains a favorable ratio of the orbital size to the stellar radius, allowing the orbit to expand as the radius expands. A prediction of this explanation for red giant mass loss is that there will be a pronounced overabundance of jovian-mass planets near 1AU around post-RGB stars. This work is supported by the National Science Foundation grant NSF-AST 0708143 to LAW.

  5. The International Deep Planet Survey. II. The frequency of directly imaged giant exoplanets with stellar mass

    NASA Astrophysics Data System (ADS)

    Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Barman, T.; Konopacky, Q.; Song, I.; Patience, J.; Lafrenière, D.; Doyon, R.; Nielsen, E. L.

    2016-10-01

    Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims: We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods: We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results: The main result of the international deep planet survey is the discovery of the HR 8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05+2.80-0.70% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300 AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30+5.95-1.55%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions: The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works. Tables 11-15 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  6. Planet Hunters: Two New Confirmed Planets and the First Kepler Seven Candidate System

    NASA Astrophysics Data System (ADS)

    Schmitt, Joseph; Wang, J.; Jek, K.; Fischer, D.; Agol, E.; Hunters, Planet

    2014-01-01

    Planet Hunters has confirmed two new planets, PH3 b and PH3 c, through transit timing variations (TTVs) and discovered a seventh planet candidate KOI-351.07, marking the first Kepler seven candidate system. Since most Kepler multiple planet candidates are true planets, KOI-351.07 is the strongest proposed seventh planet candidate in any planetary system. KOI-351 is a very compact system; all candidates have periods < 1 year. . Although errors are large, the inner five planets appear to all be sub-Neptune, while the outer two are likely gas giants. In our new confirmed system PH3, both confirmed planets experience significant TTVs, with PH3 b having an amplitude of over 5 hours. Along with the third candidate in the system (KOI-1353.02), this system may be in a Laplace resonance: Pout/Pmid = Pmid/Pin = 1.91. These new discoveries add to Planet Hunters previous successes: two previously confirmed planets and ≈ 60 other planet candidates.

  7. A HOT URANUS ORBITING THE SUPER METAL-RICH STAR HD 77338 AND THE METALLICITY-MASS CONNECTION

    SciTech Connect

    Jenkins, J. S.; Hoyer, S.; Jones, M. I.; Rojo, P.; Day-Jones, A. C.; Ruiz, M. T.; Jones, H. R. A.; Tuomi, M.; Barnes, J. R.; Pavlenko, Y. V.; Pinfield, D. J.; Murgas, F.; Ivanyuk, O.; Jordan, A.

    2013-04-01

    We announce the discovery of a low-mass planet orbiting the super metal-rich K0V star HD 77338 as part of our ongoing Calan-Hertfordshire Extrasolar Planet Search. The best-fit planet solution has an orbital period of 5.7361 {+-} 0.0015 days and with a radial velocity semi-amplitude of only 5.96 {+-} 1.74 ms{sup -1}, we find a minimum mass of 15.9{sup +4.7}{sub -5.3} M{sub Circled-Plus }. The best-fit eccentricity from this solution is 0.09{sup +0.25}{sub -0.09}, and we find agreement for this data set using a Bayesian analysis and a periodogram analysis. We measure a metallicity for the star of +0.35 {+-} 0.06 dex, whereas another recent work finds +0.47 {+-} 0.05 dex. Thus HD 77338b is one of the most metal-rich planet-host stars known and the most metal-rich star hosting a sub-Neptune-mass planet. We searched for a transit signature of HD 77338b but none was detected. We also highlight an emerging trend where metallicity and mass seem to correlate at very low masses, a discovery that would be in agreement with the core accretion model of planet formation. The trend appears to show that for Neptune-mass planets and below, higher masses are preferred when the host star is more metal-rich. Also a lower boundary is apparent in the super metal-rich regime where there are no very low mass planets yet discovered in comparison to the sub-solar metallicity regime. A Monte Carlo analysis shows that this low-mass planet desert is statistically significant with the current sample of 36 planets at the {approx}4.5{sigma} level. In addition, results from Kepler strengthen the claim for this paucity of the lowest-mass planets in super metal-rich systems. Finally, this discovery adds to the growing population of low-mass planets around low-mass and metal-rich stars and shows that very low mass planets can now be discovered with a relatively small number of data points using stable instrumentation.

  8. A Hot Uranus Orbiting the Super Metal-rich Star HD 77338 and the Metallicity-Mass Connection

    NASA Astrophysics Data System (ADS)

    Jenkins, J. S.; Jones, H. R. A.; Tuomi, M.; Murgas, F.; Hoyer, S.; Jones, M. I.; Barnes, J. R.; Pavlenko, Y. V.; Ivanyuk, O.; Rojo, P.; Jordán, A.; Day-Jones, A. C.; Ruiz, M. T.; Pinfield, D. J.

    2013-04-01

    We announce the discovery of a low-mass planet orbiting the super metal-rich K0V star HD 77338 as part of our ongoing Calan-Hertfordshire Extrasolar Planet Search. The best-fit planet solution has an orbital period of 5.7361 ± 0.0015 days and with a radial velocity semi-amplitude of only 5.96 ± 1.74 ms-1, we find a minimum mass of 15.9^{+4.7}_{-5.3} M ⊕. The best-fit eccentricity from this solution is 0.09^{+0.25}_{-0.09}, and we find agreement for this data set using a Bayesian analysis and a periodogram analysis. We measure a metallicity for the star of +0.35 ± 0.06 dex, whereas another recent work finds +0.47 ± 0.05 dex. Thus HD 77338b is one of the most metal-rich planet-host stars known and the most metal-rich star hosting a sub-Neptune-mass planet. We searched for a transit signature of HD 77338b but none was detected. We also highlight an emerging trend where metallicity and mass seem to correlate at very low masses, a discovery that would be in agreement with the core accretion model of planet formation. The trend appears to show that for Neptune-mass planets and below, higher masses are preferred when the host star is more metal-rich. Also a lower boundary is apparent in the super metal-rich regime where there are no very low mass planets yet discovered in comparison to the sub-solar metallicity regime. A Monte Carlo analysis shows that this low-mass planet desert is statistically significant with the current sample of 36 planets at the ~4.5σ level. In addition, results from Kepler strengthen the claim for this paucity of the lowest-mass planets in super metal-rich systems. Finally, this discovery adds to the growing population of low-mass planets around low-mass and metal-rich stars and shows that very low mass planets can now be discovered with a relatively small number of data points using stable instrumentation. Based on observations collected at the La Silla Paranal Observatory, ESO (Chile) with the HARPS spectrograph on the ESO 3.6 m telescope

  9. An independent planet search in the Kepler dataset. II. An extremely low-density super-Earth mass planet around Kepler-87

    NASA Astrophysics Data System (ADS)

    Ofir, Aviv; Dreizler, Stefan; Zechmeister, Mathias; Husser, Tim-Oliver

    2014-01-01

    Context. The primary goal of the Kepler mission is the measurement of the frequency of Earth-like planets around Sun-like stars. However, the confirmation of the smallest of Kepler's candidates in long periods around FGK dwarfs is extremely difficult or even beyond the limit of current radial velocity technology. Transit timing variations (TTVs) may offer the possibility for these confirmations of near-resonant multiple systems by the mutual gravitational interaction of the planets. Aims: We previously detected the second planet candidate in the KOI 1574 system. The two candidates have relatively long periods (about 114 d and 191 d) and are in 5:3 resonance. We therefore searched for TTVs in this particularly promising system. Methods: The full Kepler data was detrended with the proven SARS pipeline. The entire data allowed one to search for TTVs of the above signals, and to search for additional transit-like signals. Results: We detected strong anti-correlated TTVs of the 114 d and 191 d signals, dynamically confirming them as members of the same system. Dynamical simulations reproducing the observed TTVs allowed us to also determine the masses of the planets. We found KOI 1574.01 (hereafter Kepler-87 b) to have a radius of 13.49 ± 0.55 R⊕ and a mass of 324.2 ± 8.8 M⊕, and KOI 1574.02 (Kepler-87 c) to have a radius of 6.14 ± 0.29 R⊕ and a mass of 6.4 ± 0.8 M⊕. Both planets have low densities of 0.729 and 0.152 g cm-3, respectively, which is non-trivial for such cold and old (7-8 Gyr) planets. Specifically, Kepler-87 c is the lowest-density planet in the super-Earth mass range. Both planets are thus particularly amenable to modeling and planetary structure studies, and also present an interesting case where ground-based photometric follow-up of Kepler planets is very desirable. Finally, we also detected two more short-period super-Earth sized (<2 R⊕) planetary candidates in the system, making the relatively high multiplicity of this system notable

  10. 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

  11. DID FOMALHAUT, HR 8799, AND HL TAURI FORM PLANETS VIA THE GRAVITATIONAL INSTABILITY? PLACING LIMITS ON THE REQUIRED DISK MASSES

    SciTech Connect

    Nero, D.; Bjorkman, J. E.

    2009-09-10

    Disk fragmentation resulting from the gravitational instability has been proposed as an efficient mechanism for forming giant planets. We use the planet Fomalhaut b, the triple-planetary system HR 8799, and the potential protoplanet associated with HL Tau to test the viability of this mechanism. We choose the above systems since they harbor planets with masses and orbital characteristics favored by the fragmentation mechanism. We do not claim that these planets must have formed as the result of fragmentation, rather the reverse: if planets can form from disk fragmentation, then these systems are consistent with what we should expect to see. We use the orbital characteristics of these recently discovered planets, along with a new technique to more accurately determine the disk cooling times, to place both lower and upper limits on the disk surface density-and thus mass-required to form these objects by disk fragmentation. Our cooling times are over an order of magnitude shorter than those of Rafikov, which makes disk fragmentation more feasible for these objects. We find that the required mass interior to the planet's orbital radius is {approx}0.1 M{sub sun} for Fomalhaut b, the protoplanet orbiting HL Tau, and the outermost planet of HR 8799. The two inner planets of HR 8799 probably could not have formed in situ by disk fragmentation.

  12. Passing NASA's Planet Quest Baton from Kepler to TESS

    NASA Astrophysics Data System (ADS)

    Jenkins, J.

    Kepler vaulted into the heavens on March 7, 2009, initiating NASAs search for Earth- size planets orbiting Sun-like stars in the habitable zone, where liquid water could exist on a rocky planetary surface. In the 4 years since Kepler began science operations, a flood of photometric data on upwards of 190,000 stars of unprecedented precision and continuity has provoked a watershed of 134+ confirmed or validated planets, 3200+ planetary candidates (most sub-Neptune in size and many compara- ble to or smaller than Earth), and a resounding revolution in asteroseismology and astrophysics. The most recent discoveries include Kepler-62 with 5 planets total of which 2 are in the habitable zone with radii of 1.4 and 1.7 Re. The focus of the mission is shifting towards how to rapidly vet the 18,000+ threshold crossing events produced with each transiting planet search, and towards those studies that will allow us to understand what the data are saying about the prevalence of planets in the solar neighborhood and throughout the galaxy. This talk will provide an overview of the science results from the Kepler Mission and the work ahead to derive the frequency of Earth-size planets in the habitable zone of solar-like stars from the treasure trove of Kepler data. NASAs quest for exoplanets continues with the Transiting Exoplanet Survey Satel- lite (TESS) mission, slated for launch in May 2017 by NASAs Explorer Program. TESS will conduct an all-sky transit survey to identify the 1000 best small exoplanets in the solar neighborhood for follow up observations and characterization. TESSs targets will include all F, G, K dwarfs from +4 to +12 magnitude and all M dwarfs known within ˜200 light-years. 500,000 target stars will be observed over two years with ˜500 square degrees observed continuously for a year in each hemisphere in the James Webb Space Telescopes continuously viewable zones. Since the typical TESS target star is 5 magnitudes brighter than Kepler’s and 10 times

  13. Microlens masses from astrometry and parallax in space-based surveys: From planets to black holes

    SciTech Connect

    Gould, Andrew; Yee, Jennifer C.

    2014-03-20

    We show that space-based microlensing experiments can recover lens masses and distances for a large fraction of all events (those with individual photometric errors ≲ 0.01 mag) using a combination of one-dimensional microlens parallaxes and astrometric microlensing. This will provide a powerful probe of the mass distributions of planets, black holes, and neutron stars, the distribution of planets as a function of Galactic environment, and the velocity distributions of black holes and neutron stars. While systematics are in principle a significant concern, we show that it is possible to vet against all systematics (known and unknown) using single-epoch precursor observations with the Hubble Space Telescope roughly 10 years before the space mission.

  14. Microlens Masses from Astrometry and Parallax in Space-based Surveys: From Planets to Black Holes

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Yee, Jennifer C.

    2014-03-01

    We show that space-based microlensing experiments can recover lens masses and distances for a large fraction of all events (those with individual photometric errors <~ 0.01 mag) using a combination of one-dimensional microlens parallaxes and astrometric microlensing. This will provide a powerful probe of the mass distributions of planets, black holes, and neutron stars, the distribution of planets as a function of Galactic environment, and the velocity distributions of black holes and neutron stars. While systematics are in principle a significant concern, we show that it is possible to vet against all systematics (known and unknown) using single-epoch precursor observations with the Hubble Space Telescope roughly 10 years before the space mission.

  15. Confirmation of Earth-Mass Planets Orbiting the Millisecond Pulsar PSR B1257 + 12.

    PubMed

    Wolszczan, A

    1994-04-22

    The discovery of two Earth-mass planets orbiting an old ( approximately 10(9) years), rapidly spinning neutron star, the 6.2-millisecond radio pulsar PSR B1257+12, was announced in early 1992. It was soon pointed out that the approximately 3:2 ratio of the planets' orbital periods should lead to accurately predictable and possibly measurable gravitational perturbations of their orbits. The unambiguous detection of this effect, after 3 years of systematic timing observations of PSR B1257+12 with the 305-meter Arecibo radiotelescope, as well as the discovery of another, moon-mass object in orbit around the pulsar, constitutes irrefutable evidence that the first planetary system around a star other than the sun has been identified.

  16. 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.

  17. Constraints on the Mass and Location of Planet 9 set by Range and VLBI Observations of Spacecraft at Saturn

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.; Folkner, William M.; Park, Ryan S.; Williams, James G.

    2017-06-01

    Batygin and Brown, 2016 AJ, found that all Kuiper belt objects (KBOs) with well determined orbits having periods greater than 4000 years share nearly the same orbital plane and are apsidally aligned. They attribute this orbital clustering to the existence of a distant planet, Planet 9, well beyond Neptune, with a mass roughly ten times that of Earth. If such a planet exists, it would affect the motion of the known solar system planets, in particular Saturn, which is well observed with radiometric ranging from the Voyager and Cassini spacecraft and VLBI observations of Cassini. The current planetary ephemerides do not account for the postulated Planet 9, yet their fit to the observational data shows no obvious effect that could be attributed to neglecting that planet. However, it is possible that the effect could be absorbed by the estimated parameters used to determine the ephemerides. Those parameters include the planetary orbital elements, mass of the Sun, and the masses of the asteroids that perturb the Martian orbit. We recently updated the Voyager and Cassini data sets and extended the latter through 2017 March. We analyze the sensitivity of these data to the tidal perturbations caused by Planet 9 for a range of positions on the sky and tidal parameters (the ratio of the mass of Planet 9 to the cube of its distance from Saturn). We determine an upper bound on the tidal parameter and the most probable directions consistent with the observational data.

  18. Planetary populations in the mass-period diagram: A statistical treatment of exoplanet formation and the role of planet traps

    SciTech Connect

    Hasegawa, Yasuhiro; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2013-11-20

    The rapid growth of observed exoplanets has revealed the existence of several distinct planetary populations in the mass-period diagram. Two of the most surprising are (1) the concentration of gas giants around 1 AU and (2) the accumulation of a large number of low-mass planets with tight orbits, also known as super-Earths and hot Neptunes. We have recently shown that protoplanetary disks have multiple planet traps that are characterized by orbital radii in the disks and halt rapid type I planetary migration. By coupling planet traps with the standard core accretion scenario, we showed that one can account for the positions of planets in the mass-period diagram. In this paper, we demonstrate quantitatively that most gas giants formed at planet traps tend to end up around 1 AU, with most of these being contributed by dead zones and ice lines. We also show that a large fraction of super-Earths and hot Neptunes are formed as 'failed' cores of gas giants—this population being constituted by comparable contributions from dead zone and heat transition traps. Our results are based on the evolution of forming planets in an ensemble of disks where we vary only the lifetimes of disks and their mass accretion rates onto the host star. We show that a statistical treatment of the evolution of a large population of planetary cores caught in planet traps accounts for the existence of three distinct exoplanetary populations—the hot Jupiters, the more massive planets around r = 1 AU, and the short-period super-Earths and hot Neptunes. There are very few populations that feed into the large orbital radii characteristic of the imaged Jovian planet, which agrees with recent surveys. Finally, we find that low-mass planets in tight orbits become the dominant planetary population for low-mass stars (M {sub *} ≤ 0.7 M {sub ☉}).

  19. THE ROLE OF CORE MASS IN CONTROLLING EVAPORATION: THE KEPLER RADIUS DISTRIBUTION AND THE KEPLER-36 DENSITY DICHOTOMY

    SciTech Connect

    Lopez, Eric D.; Fortney, Jonathan J.

    2013-10-10

    We use models of coupled thermal evolution and photo-evaporative mass loss to understand the formation and evolution of the Kepler-36 system. We show that the large contrast in mean planetary density observed by Carter et al. can be explained as a natural consequence of photo-evaporation from planets that formed with similar initial compositions. However, rather than being due to differences in XUV irradiation between the planets, we find that this contrast is due to the difference in the masses of the planets' rock/iron cores and the impact that this has on mass-loss evolution. We explore in detail how our coupled models depend on irradiation, mass, age, composition, and the efficiency of mass loss. Based on fits to large numbers of coupled evolution and mass-loss runs, we provide analytic fits to understand threshold XUV fluxes for significant atmospheric loss, as a function of core mass and mass-loss efficiency. Finally we discuss these results in the context of recent studies of the radius distribution of Kepler candidates. Using our parameter study, we make testable predictions for the frequency of sub-Neptune-sized planets. We show that 1.8-4.0 R{sub ⊕} planets should become significantly less common on orbits within 10 days and discuss the possibility of a narrow 'occurrence valley' in the radius-flux distribution. Moreover, we describe how photo-evaporation provides a natural explanation for the recent observations of Ciardi et al. that inner planets are preferentially smaller within the systems.

  20. Ogle-2012-blg-0724lb: A Saturn Mass Planet Around an M-dwarf

    NASA Technical Reports Server (NTRS)

    Hirao, Y.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Suzuki, D.; Koshimoto, N.; Abe, F.; Asakura, Y.; Bhattacharya, A.

    2016-01-01

    We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q = (1.58 +/- 0.15) x 10(exp -3). By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of M(sub L) = 0.29(+0.33/-0.16) solar mass located at D(sub L) = 6.7(+1.1/-1.2) kpc away from the Earth and the companion's mass is m(sub P) = 0.47(+0.54/-0.26) M(Jup). The projected planet- host separation is a falsum = 1.6(+0.4/-0.3) AU. Because the lens-source relative proper motion is relatively high, future highresolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters (0.2 less than m(sub P)/M(sub Jup) less than 1) in contrast to a lack of Jupiters (approximately 1-2 M(sub Jup)) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.

  1. The Planets Around Low-Mass Stars (PALMS) Direct Imaging Survey

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, M. C.; Shkolnik, E.; Mann, A.; Tamura, M.

    2013-01-01

    Direct imaging is the only method to study the outer architecture (>10 AU) of extrasolar planetary systems in a targeted fashion. Previous imaging surveys have primarily focused on intermediate- and high-mass stars because of the relative dearth of known nearby young M dwarfs. As a result, even though M dwarfs make up 70% of stars in our galaxy, there are few constraints on the population of giant planets at moderate separations (10-100 AU) in this stellar mass regime. We present results from an ongoing high-contrast adaptive optics imaging survey targeting newly identified nearby (<35 pc) young (<300 Myr) M dwarfs with Keck-2/NIRC2 and Subaru/HiCIAO. We have already discovered four young brown dwarf companions with masses between 30-70 Mjup; two of these are members of the ~120 Myr AB Dor moving group, and another one will yield a dynamical mass in the near future. Follow-up optical and near-infrared spectroscopy of these companions reveal spectral types of late-M to early-L and spectroscopic indicators of youth such as angular H-band morphologies, weak J-band alkali lines, and Li absorption and Halpha emission in one target. Altogether our survey is sensitive to planet masses a few times that of Jupiter at separations down to ~10 AU. With a sample size of roughly 80 single M dwarfs, this program represents the deepest and most extensive imaging search for planets around young low-mass stars to date.

  2. Ogle-2012-blg-0724lb: A Saturn Mass Planet Around an M-dwarf

    NASA Technical Reports Server (NTRS)

    Hirao, Y.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Suzuki, D.; Koshimoto, N.; Abe, F.; Asakura, Y.; Bhattacharya, A.

    2016-01-01

    We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q = (1.58 +/- 0.15) x 10(exp -3). By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of M(sub L) = 0.29(+0.33/-0.16) solar mass located at D(sub L) = 6.7(+1.1/-1.2) kpc away from the Earth and the companion's mass is m(sub P) = 0.47(+0.54/-0.26) M(Jup). The projected planet- host separation is a falsum = 1.6(+0.4/-0.3) AU. Because the lens-source relative proper motion is relatively high, future highresolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters (0.2 less than m(sub P)/M(sub Jup) less than 1) in contrast to a lack of Jupiters (approximately 1-2 M(sub Jup)) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.

  3. Migrating Planets

    NASA Astrophysics Data System (ADS)

    Murray, N.; Hansen, B.; Holman, M.; Tremaine, S.

    1998-01-01

    A planet orbiting in a disk of planetesimals can experience an instability in which it migrates to smaller orbital radii. Resonant interactions between the planet and planetesimals remove angular momentum from the planetesimals, increasing their eccentricities. Subsequently, the planetesimals either collide with or are ejected by the planet, reducing the semimajor axis of the planet. If the surface density of planetesimals exceeds a critical value, corresponding to 0.03 solar masses of gas inside the orbit of Jupiter, the planet will migrate inward a large distance. This instability may explain the presence of Jupiter-mass objects in small orbits around nearby stars.

  4. Some physical properties predicted for the putative Planet Nine of the solar system

    NASA Astrophysics Data System (ADS)

    Toth, I.

    2016-08-01

    Context. Nothing is known as yet about the physical properties of the putative Planet Nine (P9), which is hypothesized to orbit at the fringes of the solar system. Two groups of observers are using the eight-meter Subaru telescope to search for P9. Early estimates and predictions are important to characterize this hypothetic planet. We here predict some properties to compare them with the observed physical properties when Planet Nine has been unambiguously detected comparisons between the predicted and observed physical properties. Aims: We estimate the size, apparent observable brightness, shortest rotation period, and extension of the stable orbital region of possible satellites of P9. Methods: Using the predicted mass and adopting a possible mean bulk density range of P9, we computed its radius and assumed a domain for its geometric albedo. We then determined the apparent magnitude along its elliptic orbit. By testing different plausible physical models of a sub-Neptune class planet, we estimated the regions of stability and destruction versus rotational breakup in the radius-rotational period plane. In this plane the shortest rotational period is constrained by the possible size range of P9 and the separation curves. We applied quantitative measures of the stability domain of possible satellites orbiting P9 to quantify the search region in which to find possible satellite companions of the putative trans-Neptunian giant planet of our solar system. Results: Its predicted apparent magnitude even near aphelion allows discovering P9 with eight-meter class telescopes. P9 is stable against rotational breakup for stronger material if the period is longer than ~6 h, and for weaker material if the period is longer than ~13 h. The Szebehely stability domain for possible satellites of the hypothetical P9 is very large: for a small satellite it extents to ~1.7 au from the planet, and the longest orbital period of the satellite in this orbit is ~396 yr. For a possible twin

  5. OGLE-2012-BLG-0724Lb: A Saturn-mass Planet around an M Dwarf

    NASA Astrophysics Data System (ADS)

    Hirao, Y.; Udalski, A.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Suzuki, D.; Koshimoto, N.; Abe, F.; Asakura, Y.; Bhattacharya, A.; Freeman, M.; Fukui, A.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Matsuo, T.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Saito, To.; Sharan, A.; Shibai, H.; Sullivan, D. J.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Kozłowski, S.; Pietrukowicz, P.; Soszyński, I.; Wyrzykowski, Ł.; Ulaczyk, K.; OGLE Collaboration

    2016-06-01

    We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q=(1.58+/- 0.15)× {10}-3. By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of {M}{{L}}={0.29}-0.16+0.33 {M}⊙ located at {D}{{L}}={6.7}-1.2+1.1 {{kpc}} away from the Earth and the companion’s mass is {m}{{P}}={0.47}-0.26+0.54 {M}{{Jup}}. The projected planet-host separation is {a}\\perp ={1.6}-0.3+0.4 {{AU}}. Because the lens-source relative proper motion is relatively high, future high-resolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters (0.2\\lt {m}{{P}}/{M}{{Jup}}\\lt 1) in contrast to a lack of Jupiters (˜ 1{--}2 {M}{{Jup}}) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.

  6. The SOPHIE search for northern extrasolar planets. III. A Jupiter-mass companion around HD 109246

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Eggenberger, A.; Santos, N. C.; Lovis, C.; Bouchy, F.; Hébrard, G.; Arnold, L.; Bonfils, X.; Delfosse, X.; Desort, M.; Díaz, R. F.; Ehrenreich, D.; Forveille, T.; Gallenne, A.; Lagrange, A. M.; Moutou, C.; Udry, S.; Pepe, F.; Perrier, C.; Perruchot, S.; Pont, F.; Queloz, D.; Santerne, A.; Ségransan, D.; Vidal-Madjar, A.

    2010-11-01

    We report the detection of a Jupiter-mass planet discovered with the SOPHIE spectrograph mounted on the 1.93-m telescope at the Haute-Provence Observatory. The new planet orbits HD 109246, a G0V star slightly more metallic than the Sun. HD 109246b has a minimum mass of 0.77 MJup, an orbital period of 68 days, and an eccentricity of 0.12. It is placed in a sparsely populated region of the period distribution of extrasolar planets. We also present a correction method for the so-called seeing effect that affects the SOPHIE radial velocities. We complement this discovery announcement with a description of some calibrations that are implemented in the SOPHIE automatic reduction pipeline. These calibrations allow the derivation of the photon-noise radial velocity uncertainty and some useful stellar properties (v sin i, [Fe/H], log R’HK) directly from the SOPHIE data. Based on observations made with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS/OAMP), France (program 07A.PNP.CONS).RV tables (Tables C.1 and C.2) are only available in electronic form 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/523/A88

  7. Advanced Ion Mass Spectrometer for Giant Planet Ionospheres, Magnetospheres and Moons

    NASA Astrophysics Data System (ADS)

    Sittler, EC; Cooper, JF; Paschalidis, N.; Jones, SL; Rodriguez, M.; Ali, A.; Coplan, MA; Chornay, DJ; Sturner; Bateman, FB; Andre, N.; Fedorov, A.; Wurz, P.

    2015-10-01

    The Advanced Ion Composition Spectrometer (AIMS) has been under development from various NASA sources (NASA LWSID, NASA ASTID, NASA Goddard IRADs) to measure elemental, isotopic, and simple molecular composition abundances of 1 eV/e to 25 keV/e hot ions with wide field-of-view (FOV) in the 1 - 60 amu mass range at mass resolution M/ΔM ≤ 60 over a wide dynamic range of intensities and penetrating radiation background from the inner magnetospheres of Jupiter and Saturn to the outer magnetospheric boundary regions and the upstream solar wind. This instrument will work for both spinning spacecraft and 3-axis stabilized spacecraft with wide field-of-view capability in both cases. It will measure the ion velocity distribution functions (IVDF) for the individual ion species; ion velocity moments of the IVDF will give the fluid parameters (density, flow velocity and temperature) of the individual ion species. Outer planet mission applications are Io Observer, Jupiter Europa Orbiter/Europa Clipper, Enceladus Orbiter, and Uranus Orbiter as described in the decadal survey, but would also be valuable for inclusion on other missions to outer planet destinations such as Saturn- Titan and Neptune-Triton and for future missions to terrestrial planets, Venus and Mars, the Moon, asteroids, and comets, and of course for geospace applications to the Earth.

  8. AN UNDERSTANDING OF THE SHOULDER OF GIANTS: JOVIAN PLANETS AROUND LATE K DWARF STARS AND THE TREND WITH STELLAR MASS

    SciTech Connect

    Gaidos, Eric; Fischer, Debra A.; Mann, Andrew W.; Howard, Andrew W.

    2013-07-01

    Analyses of exoplanet statistics suggest a trend of giant planet occurrence with host star mass, a clue to how planets like Jupiter form. One missing piece of the puzzle is the occurrence around late K dwarf stars (masses of 0.5-0.75 M{sub Sun} and effective temperatures of 3900-4800 K). We analyzed four years of Doppler radial velocity (RVs) data for 110 late K dwarfs, one of which hosts two previously reported giant planets. We estimate that 4.0% {+-} 2.3% of these stars have Saturn-mass or larger planets with orbital periods <245 days, depending on the planet mass distribution and RV variability of stars without giant planets. We also estimate that 0.7% {+-} 0.5% of similar stars observed by Kepler have giant planets. This Kepler rate is significantly (99% confidence) lower than that derived from our Doppler survey, but the difference vanishes if only the single Doppler system (HIP 57274) with completely resolved orbits is considered. The difference could also be explained by the exclusion of close binaries (without giant planets) from the Doppler but not Kepler surveys, the effect of long-period companions and stellar noise on the Doppler data, or an intrinsic difference between the two populations. Our estimates for late K dwarfs bridge those for solar-type stars and M dwarfs, and support a positive trend with stellar mass. Small sample size precludes statements about finer structure, e.g., a ''shoulder'' in the distribution of giant planets with stellar mass. Future surveys such as the Next Generation Transit Survey and the Transiting Exoplanet Satellite Survey will ameliorate this deficiency.

  9. EFFECTS OF DYNAMICAL EVOLUTION OF GIANT PLANETS ON SURVIVAL OF TERRESTRIAL PLANETS

    SciTech Connect

    Matsumura, Soko; Ida, Shigeru; Nagasawa, Makiko

    2013-04-20

    The orbital distributions of currently observed extrasolar giant planets allow marginally stable orbits for hypothetical, terrestrial planets. In this paper, we propose that many of these systems may not have additional planets on these ''stable'' orbits, since past dynamical instability among giant planets could have removed them. We numerically investigate the effects of early evolution of multiple giant planets on the orbital stability of the inner, sub-Neptune-like planets which are modeled as test particles, and determine their dynamically unstable region. Previous studies have shown that the majority of such test particles are ejected out of the system as a result of close encounters with giant planets. Here, we show that secular perturbations from giant planets can remove test particles at least down to 10 times smaller than their minimum pericenter distance. Our results indicate that, unless the dynamical instability among giant planets is either absent or quiet like planet-planet collisions, most test particles down to {approx}0.1 AU within the orbits of giant planets at a few AU may be gone. In fact, out of {approx}30% of survived test particles, about three quarters belong to the planet-planet collision cases. We find a good agreement between our numerical results and the secular theory, and present a semi-analytical formula which estimates the dynamically unstable region of the test particles just from the evolution of giant planets. Finally, our numerical results agree well with the observations, and also predict the existence of hot rocky planets in eccentric giant planet systems.

  10. Range of outward migration and influence of the disc's mass on the migration of giant planet cores

    NASA Astrophysics Data System (ADS)

    Bitsch, B.; Kley, W.

    2011-12-01

    Context. The migration of planets plays an important role in the early planet-formation process. An important problem has been that standard migration theories predict very rapid inward migration, which poses problems for population synthesis models. However, it has been shown recently that low-mass planets (20-30 MEarth) that are still embedded in the protoplanetary disc can migrate outwards under certain conditions. Simulations have been performed mostly for planets at given radii for a particular disc model. Aims: Here, we plan to extend previous work and consider different masses of the disc to quantify the influence of the physical disc conditions on planetary migration. The migration behaviour of the planets will be analysed for a variety of positions in the disc. Methods: We perform three-dimensional (3D) radiation hydrodynamical simulations of embedded planets in protoplanetary discs. We use the explicit-implicit 3D hydrodynamical code NIRVANA that includes full tensor viscosity, and implicit radiation transport. For planets on circular orbits at various locations we measure the radial dependence of the torques for three different planetary masses. Results: For all considered planet masses (20-30 MEarth) in this study we find outward migration within a limited radial range of the disc, typically from about 0.5 up to 1.5-2.5 aJup. Inside and outside this interval, migration is inward and given by the Lindblad value for large radii. Interestingly, the fastest outward migration occurs at a radius of about aJup for different disc and planet masses. Because outward migration stops at a certain location in the disc, there exists a zero-torque distance for planetary embryos, where they can continue to grow without moving too fast. For higher disc masses (Mdisc > 0.02 M⊙) convection ensues, which changes the structure of the disc and therefore the torque on the planet as well. Conclusions: Outward migration stops at different points in the disc for different

  11. 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

  12. 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

  13. Measurements of Kepler Planet Masses and Eccentricities from Transit Timing Variations: Analytic and N-body Results

    NASA Astrophysics Data System (ADS)

    Hadden, Sam; Lithwick, Yoram

    2015-12-01

    Several Kepler planets reside in multi-planet systems where gravitational interactions result in transit timing variations (TTVs) that provide exquisitely sensitive probes of their masses of and orbits. Measuring these planets' masses and orbits constrains their bulk compositions and can provide clues about their formation. However, inverting TTV measurements in order to infer planet properties can be challenging: it involves fitting a nonlinear model with a large number of parameters to noisy data, often with significant degeneracies between parameters. I present results from two complementary approaches to TTV inversion: Markov chain Monte Carlo simulations that use N-body integrations to compute transit times and a simplified analytic model for computing the TTVs of planets near mean motion resonances. The analytic model allows for straightforward interpretations of N-body results and provides an independent estimate of parameter uncertainties that can be compared to MCMC results which may be sensitive to factors such as priors. We have conducted extensive MCMC simulations along with analytic fits to model the TTVs of dozens of Kepler multi-planet systems. We find that the bulk of these sub-Jovian planets have low densities that necessitate significant gaseous envelopes. We also find that the planets' eccentricities are generally small but often definitively non-zero.

  14. Hydrodynamics of giant planet formation. II - Model equations and critical mass. III - Jupiter's nucleated instability

    SciTech Connect

    Wuchterl, G. )

    1991-05-01

    A spherically symmetric protoplanetary model with a growing rigid core and a gaseous envelope of solar composition is used to investigate the character and evolution of the nucleated instability; the model equations formulated are used to follow the static evolution of a protogiant planet in the 'Kyoto' solar nebula, lying at Jupiter's solar distance, to its critical core mass. Convective energy transfer has been formulated for inclusion in implicit radiation hydrodynamical computations. It is established that collapse need not occur at the critical mass, which in agreement with earlier investigations is found to be of the order of 13.1 earth masses. This model is then used as an initial condition for a radiation hydrodynamical calculation of the nucleated instability. It is found that nonlinear hydrodynamic waves are excited by a kappa mechanism, and that an outflow is driven. 56 refs.

  15. Advanced Ion Mass Spectrometer for Giant Planet Ionosphere, Magnetospheres and Moons

    NASA Astrophysics Data System (ADS)

    Sittler, Edward; Cooper, John; Paschalidis, Nick; Jones, Sarah; Brinkerhoff, William; Paterson, William; Ali, Ashraf; Coplan, Michael; Chornay, Dennis; Sturner, Steve; Benna, Mehdi; Bateman, Fred; Fontaine, Dominique; Verdeil, Christophe; Andre, Nicolas; Blanc, Michel; Wurz, Peter

    2017-01-01

    We present our Advanced Ion Mass Spectrometer (AIMS) for outer planet missions which has been under development from various NASA sources (NASA Living with a Star Instrument Development (LWSID), NASA Astrobiology Instrument Development (ASTID), NASA Goddard Internal Research and Development (IRAD)s) to measure elemental, isotopic, and simple molecular composition abundances of 1 V to 25 kV hot ions with wide field-of-view (FOV) in the 1 - 60 amu mass range at mass resolution M/ ΔM <= 60 over a wide dynamic range of particle intensities and penetrating radiation background from the inner magnetospheres of Jupiter and Saturn to the outer magnetospheric boundary regions and the upstream solar wind. This instrument will work for both spinning spacecraft and 3-axis stabilized spacecraft. AIMS will measure the ion velocity distribution functions (VDF) for the individual ion species from which velocity moments will give their ion density, flow velocity and temperature.

  16. The mass of the super-Earth orbiting the brightest Kepler planet hosting star

    NASA Astrophysics Data System (ADS)

    Lopez-Morales, Mercedes; HARPS-N Team

    2016-01-01

    HD 179070, aka Kepler-21, is a V = 8.25 oscillating F6IV star and the brightest exoplanet host discovered by Kepler. An early analysis of the Q0 - Q5 Kepler light curves by Howell et al. (2012) revealed transits of a planetary companion, Kepler-21b, with a radius of 1.6 R_Earth and an orbital period of 2.7857 days. However, they could not determine the mass of the planet from the initial radial velocity observations with Keck-HIRES, and were only able to impose a 2s upper limit of about 10 M_Earth. Here we present 82 new radial velocity observations of this system obtained with the HARPS-N spectrograph. We detect the Doppler shift signal of Kepler-21b at the 3.6s level, and measure a planetary mass of 5.9 ± 1.6 M_Earth. We also update the radius of the planet to 1.65 ± 0.08 R_Earth, using the now available Kepler Q0 - Q17 photometry for this target. The mass of Kepler-21b appears to fall on the apparent dividing line between super-Earths that have lost all the material in their outer layers and those that have retained a significant amount of volatiles. Based on our results Kepler-21b belongs to the first group. Acknowledgement: This work was supported by funding from the NASA XRP Program and the John Templeton Foundation.

  17. Atmospheric mass loss during planet formation: The importance of planetesimal impacts

    NASA Astrophysics Data System (ADS)

    Schlichting, Hilke E.; Sari, Re'em; Yalinewich, Almog

    2015-02-01

    Quantifying the atmospheric mass loss during planet formation is crucial for understanding the origin and evolution of planetary atmospheres. We examine the contributions to atmospheric loss from both giant impacts and planetesimal accretion. Giant impacts cause global motion of the ground. Using analytic self-similar solutions and full numerical integrations we find (for isothermal atmospheres with adiabatic index γ=5/3) that the local atmospheric mass loss fraction for ground velocities vg≲0.25vesc is given by χloss=(1.71, where vesc is the escape velocity from the target. Yet, the global atmospheric mass loss is a weaker function of the impactor velocity vImp and mass mImp and given by Xloss≃0.4x+1.4x2-0.8x3 (isothermal atmosphere) and Xloss≃0.4x+1.8x2-1.2x3 (adiabatic atmosphere), where x=(vImpm/vescM). Atmospheric mass loss due to planetesimal impacts proceeds in two different regimes: (1) large enough impactors m≳√{2}ρ0( (25 km for the current Earth), are able to eject all the atmosphere above the tangent plane of the impact site, which is h/2R of the whole atmosphere, where h, R and ρ0 are the atmospheric scale height, radius of the target, and its atmospheric density at the ground. (2) Smaller impactors, but above m>4πρ0h3 (1 km for the current Earth) are only able to eject a fraction of the atmospheric mass above the tangent plane. We find that the most efficient impactors (per unit impactor mass) for atmospheric loss are planetesimals just above that lower limit (2 km for the current Earth). For impactor flux size distributions parametrized by a single power law, N(>r)∝r, with differential power law index q, we find that for 1mass loss proceeds in regime (1) whereas for q>3 the mass loss is dominated by regime (2). Impactors with m≲4πρ0h3 are not able to eject any atmosphere. Despite being bombarded by the same planetesimal population, we find that the current differences in Earth's and Venus' atmospheric masses

  18. 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.

  19. 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.

  20. THE VLA VIEW OF THE HL TAU DISK: DISK MASS, GRAIN EVOLUTION, AND EARLY PLANET FORMATION

    SciTech Connect

    Carrasco-González, Carlos; Rodríguez, Luis F.; Galván-Madrid, Roberto; Henning, Thomas; Linz, Hendrik; Birnstiel, Til; Boekel, Roy van; Klahr, Hubert; Chandler, Claire J.; Pérez, Laura; Anglada, Guillem; Macias, Enrique; Osorio, Mayra; Flock, Mario; Menten, Karl; Testi, Leonardo; Torrelles, José M.; Zhu, Zhaohuan E-mail: l.rodriguez@crya.unam.mx E-mail: henning@mpia.de

    2016-04-10

    The first long-baseline ALMA campaign resolved the disk around the young star HL Tau into a number of axisymmetric bright and dark rings. Despite the very young age of HL Tau, these structures have been interpreted as signatures for the presence of (proto)planets. The ALMA images triggered numerous theoretical studies based on disk–planet interactions, magnetically driven disk structures, and grain evolution. Of special interest are the inner parts of disks, where terrestrial planets are expected to form. However, the emission from these regions in HL Tau turned out to be optically thick at all ALMA wavelengths, preventing the derivation of surface density profiles and grain-size distributions. Here, we present the most sensitive images of HL Tau obtained to date with the Karl G. Jansky Very Large Array at 7.0 mm wavelength with a spatial resolution comparable to the ALMA images. At this long wavelength, the dust emission from HL Tau is optically thin, allowing a comprehensive study of the inner disk. We obtain a total disk dust mass of (1–3) × 10{sup −3} M {sub ⊙}, depending on the assumed opacity and disk temperature. Our optically thin data also indicate fast grain growth, fragmentation, and formation of dense clumps in the inner densest parts of the disk. Our results suggest that the HL Tau disk may be actually in a very early stage of planetary formation, with planets not already formed in the gaps but in the process of future formation in the bright rings.

  1. The VLA View of the HL Tau Disk: Disk Mass, Grain Evolution, and Early Planet Formation

    NASA Astrophysics Data System (ADS)

    Carrasco-González, Carlos; Henning, Thomas; Chandler, Claire J.; Linz, Hendrik; Pérez, Laura; Rodríguez, Luis F.; Galván-Madrid, Roberto; Anglada, Guillem; Birnstiel, Til; van Boekel, Roy; Flock, Mario; Klahr, Hubert; Macias, Enrique; Menten, Karl; Osorio, Mayra; Testi, Leonardo; Torrelles, José M.; Zhu, Zhaohuan

    2016-04-01

    The first long-baseline ALMA campaign resolved the disk around the young star HL Tau into a number of axisymmetric bright and dark rings. Despite the very young age of HL Tau, these structures have been interpreted as signatures for the presence of (proto)planets. The ALMA images triggered numerous theoretical studies based on disk-planet interactions, magnetically driven disk structures, and grain evolution. Of special interest are the inner parts of disks, where terrestrial planets are expected to form. However, the emission from these regions in HL Tau turned out to be optically thick at all ALMA wavelengths, preventing the derivation of surface density profiles and grain-size distributions. Here, we present the most sensitive images of HL Tau obtained to date with the Karl G. Jansky Very Large Array at 7.0 mm wavelength with a spatial resolution comparable to the ALMA images. At this long wavelength, the dust emission from HL Tau is optically thin, allowing a comprehensive study of the inner disk. We obtain a total disk dust mass of (1-3) × 10-3 M ⊙, depending on the assumed opacity and disk temperature. Our optically thin data also indicate fast grain growth, fragmentation, and formation of dense clumps in the inner densest parts of the disk. Our results suggest that the HL Tau disk may be actually in a very early stage of planetary formation, with planets not already formed in the gaps but in the process of future formation in the bright rings.

  2. Secure Mass Measurements from Transit Timing: 10 Kepler Exoplanets between 3 and 8 M⊕ with Diverse Densities and Incident Fluxes

    NASA Astrophysics Data System (ADS)

    Jontof-Hutter, Daniel; Ford, Eric B.; Rowe, Jason F.; Lissauer, Jack J.; Fabrycky, Daniel C.; Van Laerhoven, Christa; Agol, Eric; Deck, Katherine M.; Holczer, Tomer; Mazeh, Tsevi

    2016-03-01

    We infer dynamical masses in eight multiplanet systems using transit times measured from Kepler's complete data set, including short-cadence data where available. Of the 18 dynamical masses that we infer, 10 pass multiple tests for robustness. These are in systems Kepler-26 (KOI-250), Kepler-29 (KOI-738), Kepler-60 (KOI-2086), Kepler-105 (KOI-115), and Kepler-307 (KOI-1576). Kepler-105 c has a radius of 1.3 R⊕ and a density consistent with an Earth-like composition. Strong transit timing variation (TTV) signals were detected from additional planets, but their inferred masses were sensitive to outliers or consistent solutions could not be found with independently measured transit times, including planets orbiting Kepler-49 (KOI-248), Kepler-57 (KOI-1270), Kepler-105 (KOI-115), and Kepler-177 (KOI-523). Nonetheless, strong upper limits on the mass of Kepler-177 c imply an extremely low density of ˜0.1 g cm-3. In most cases, individual orbital eccentricities were poorly constrained owing to degeneracies in TTV inversion. For five planet pairs in our sample, strong secular interactions imply a moderate to high likelihood of apsidal alignment over a wide range of possible eccentricities. We also find solutions for the three planets known to orbit Kepler-60 in a Laplace-like resonance chain. However, nonlibrating solutions also match the transit timing data. For six systems, we calculate more precise stellar parameters than previously known, enabling useful constraints on planetary densities where we have secure mass measurements. Placing these exoplanets on the mass-radius diagram, we find that a wide range of densities is observed among sub-Neptune-mass planets and that the range in observed densities is anticorrelated with incident flux.

  3. A lower radius and mass for the transiting extrasolar planet HAT-P-8 b

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Southworth, J.; Ciceri, S.; Fortney, J. J.; Morley, C. V.; Dittmann, J. A.; Tregloan-Reed, J.; Bruni, I.; Barbieri, M.; Evans, D. F.; D'Ago, G.; Nikolov, N.; Henning, Th.

    2013-03-01

    Context. The extrasolar planet HAT-P-8 b was thought to be one of the more inflated transiting hot Jupiters. Aims: By using new and existing photometric data, we computed precise estimates of the physical properties of the system. Methods: We present photometric observations comprising eleven light curves covering six transit events, obtained using five medium-class telescopes and telescope-defocussing technique. One transit was simultaneously obtained through four optical filters, and two transits were followed contemporaneously from two observatories. We modelled these and seven published datasets using the jktebop code. The physical parameters of the system were obtained from these results and from published spectroscopic measurements. In addition, we investigated the theoretically-predicted variation of the apparent planetary radius as a function of wavelength, covering the range 330-960 nm. Results: We find that HAT-P-8 b has a significantly lower radius (1.321 ± 0.037 RJup) and mass (1.275 ± 0.053 MJup) compared to previous estimates (1.50-0.06+0.08 R_{Jup} and 1.52-0.16+0.18 M_{Jup} respectively). We also detect a radius variation in the optical bands that, when compared with synthetic spectra of the planet, may indicate the presence of a strong optical absorber, perhaps TiO and VO gases, near the terminator of HAT-P-8 b. Conclusions: These new results imply that HAT-P-8 b is not significantly inflated, and that its position in the planetary mass-radius diagram is congruent with those of many other transiting extrasolar planets. Full Table 2 is only available in electronic form 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/551/A11

  4. THE DEUTERIUM-BURNING MASS LIMIT FOR BROWN DWARFS AND GIANT PLANETS

    SciTech Connect

    Spiegel, David S.; Burrows, Adam; Milsom, John A. E-mail: burrows@astro.princeton.edu

    2011-01-20

    There is no universally acknowledged criterion to distinguish brown dwarfs from planets. Numerous studies have used or suggested a definition based on an object's mass, taking the {approx}13 Jupiter mass (M{sub J} ) limit for the ignition of deuterium. Here, we investigate various deuterium-burning masses for a range of models. We find that, while 13 M{sub J} is generally a reasonable rule of thumb, the deuterium fusion mass depends on the helium abundance, the initial deuterium abundance, the metallicity of the model, and on what fraction of an object's initial deuterium abundance must combust in order for the object to qualify as having burned deuterium. Even though, for most proto-brown dwarf conditions, 50% of the initial deuterium will burn if the object's mass is {approx}(13.0 {+-} 0.8) M{sub J} , the full range of possibilities is significantly broader. For models ranging from zero-metallicity to more than three times solar metallicity, the deuterium-burning mass ranges from {approx}11.0 M{sub J} (for three times solar metallicity, 10% of initial deuterium burned) to {approx}16.3 M{sub J} ( for zero metallicity, 90% of initial deuterium burned).

  5. Habitability of terrestrial-mass planets in the HZ of M Dwarfs - I. H/He-dominated atmospheres

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Mohanty, Subhanjoy

    2016-07-01

    The ubiquity of M dwarfs, combined with the relative ease of detecting terrestrial-mass planets around them, has made them prime targets for finding and characterizing planets in the `habitable zone' (HZ). However, Kepler finds that terrestrial-mass exoplanets are often born with voluminous H/He envelopes, comprising mass-fractions (Menv/Mcore) ≳1 per cent. If these planets retain such envelopes over Gyr time-scales, they will not be `habitable' even within the HZ. Given the strong X-ray/UV fluxes of M dwarfs, we study whether sufficient envelope mass can be photoevaporated away for these planets to become habitable. We improve upon previous work by using hydrodynamic models that account for radiative cooling as well as the transition from hydrodynamic to ballistic escape. Adopting a template active M dwarf XUV spectrum, including stellar evolution, and considering both evaporation and thermal evolution, we show that: (1) the mass-loss is (considerably) lower than previous estimates that use an `energy-limited' formalism and ignore the transition to Jeans escape; (2) at the inner edge of the HZ, planets with core mass ≲ 0.9 M⊕ can lose enough H/He to become habitable if their initial envelope mass-fraction is ˜1 per cent; (3) at the outer edge of the HZ, evaporation cannot remove a ˜1 per cent H/He envelope even from cores down to 0.8 M⊕. Thus, if planets form with bulky H/He envelopes, only those with low-mass cores may eventually be habitable. Cores ≳1 M⊕, with ≳1 per cent natal H/He envelopes, will not be habitable in the HZ of M dwarfs.

  6. Influence of Sudden Change of Solar Mass in the PN Stage on the Orbit of Earth-Like Planet

    NASA Astrophysics Data System (ADS)

    Zhu, Yunfeng; Pan, Caijuan; Pan, Dasheng; Huang, Hongqiang; Chen, Zhi-Fu

    2014-09-01

    Assuming that the terminated mass is confined within the range of 0.4551-0.5813 M ⊙ when the sun is going to evolve into a white dwarf, the velocity of the sun projecting the shell in the PN stage is much greater than the revolving velocity of the earth-like planet, therefore, we think that the solar mass change is instantaneous.

  7. THE EVOLUTION OF THE SOLAR NEBULA I. EVOLUTION OF THE GLOBAL PROPERTIES AND PLANET MASSES

    SciTech Connect

    Jin Liping; Sui Ning E-mail: suining@email.jlu.edu.c

    2010-02-20

    We investigate the formation, structure, and evolution of the solar nebula by including nonuniform viscosity and the mass influx from the gravitational collapse of the molecular cloud core. The calculations are done by using currently accepted viscosity, which is nonuniform, and probable mass influx from star formation theory. In the calculation of the viscosity, we include the effect of magnetorotational instability. The radial distributions of the surface density and other physical quantities of the nebula are significantly different from nebula models with constant alpha viscosity and the models which do not include the mass influx. We find that the nebula starts to form from the inner boundary because of the inside-out collapse and then expands due to viscosity. The surface density is not a monotonic function of the radius like the case of uniform viscosity. There are minimums near 1.5 AU due to nonuniform viscosity. The general shape of the surface density is sustained before the mass influx stops because the mass supply offsets mass loss accreted onto the protosun and provides the mass needed for the nebula expansion. We show that not all protoplanetary disks experience gravitational instability during some periods of their lifetime. We find that the nebula becomes gravitationally unstable in some durations when the angular momentum of the cloud core is high. Our numerical calculations confirm Jin's early suggestion that nonuniform viscosity explains the differences in mass and gas content among Jovian planets. Our calculations of nebular evolution show that the nebula temperature is less than 1200 K. Even in the inner portion of the nebula, refractory material from the molecular cloud may survive and refractory condensates may form.

  8. Mass inventory of the giant-planet formation zone in a solar nebula analogue

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Bergin, Edwin A.; Blake, Geoffrey A.; Cleeves, L. Ilsedore; Schwarz, Kamber R.

    2017-06-01

    The initial mass distribution in the solar nebula is a critical input to planet formation models that seek to reproduce today's Solar System 1 . Traditionally, constraints on the gas mass distribution are derived from observations of the dust emission from disks 2,3 , but this approach suffers from large uncertainties in dust opacity and gas-to-dust ratio 2 . On the other hand, previous observations of gas tracers only probe surface layers above the bulk mass reservoir 4 . Here we present the first partially spatially resolved observations of the 13C18O J = 3-2 line emission in the closest protoplanetary disk, TW Hydrae, a gas tracer that probes the bulk mass distribution. Combining it with the C18O J = 3-2 emission and the previously detected HD J = 1-0 flux, we directly constrain the mid-plane temperature and optical depths of gas and dust emission. We report a gas mass distribution with radius, R, of 13 - 5 + 8 × ( R / 20 .5 au ) - 0.9 - 0.3 + 0.4  g cm-2 in the expected formation zone of gas and ice giants (5-21 au). We find that the mass ratio of total gas to millimetre-sized dust is 140 in this region, suggesting that at least 2.4M⊕ of dust aggregates have grown to centimetre sizes (and perhaps much larger). The radial distribution of gas mass is consistent with a self-similar viscous disk profile but much flatter than the posterior extrapolation of mass distribution in our own and extrasolar planetary systems.

  9. THE NASA-UC ETA-EARTH PROGRAM. II. A PLANET ORBITING HD 156668 WITH A MINIMUM MASS OF FOUR EARTH MASSES

    SciTech Connect

    Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Johnson, John Asher; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.

    2011-01-10

    We report the discovery of HD 156668 b, an extrasolar planet with a minimum mass of M{sub P} sin i = 4.15 M{sub +}. This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 days. The Doppler semi-amplitude of this planet, K = 1.89 m s{sup -1}, is among the lowest ever detected, on par with the detection of GJ 581 e using HARPS. A longer period (P {approx} 2.3 years), low-amplitude signal of unknown origin was also detected in the radial velocities and was filtered out of the data while fitting the short-period planet. Additional data are required to determine if the long-period signal is due to a second planet, stellar activity, or another source. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 156668 (an old, quiet K3 dwarf) is photometrically constant over the radial velocity period to 0.1 mmag, supporting the existence of the planet. No transits were detected down to a photometric limit of {approx}3 mmag, ruling out transiting planets dominated by extremely bloated atmospheres, but not precluding a transiting solid/liquid planet with a modest atmosphere.

  10. The Stellar Obliquity, Planet Mass, and Very Low Albedo of Qatar-2 from K2 Photometry

    NASA Astrophysics Data System (ADS)

    Dai, Fei; Winn, Joshua N.; Yu, Liang; Albrecht, Simon

    2017-01-01

    The Qatar-2 transiting exoplanet system was recently observed in short-cadence mode by Kepler as part of K2 Campaign 6. We identify dozens of starspot-crossing events, when the planet eclipses a relatively dark region of the stellar photosphere. The observed patterns of these events demonstrate that the planet always transits over the same range of stellar latitudes and, therefore, that the stellar obliquity is less than about 10°. We support this conclusion with two different modeling approaches: one based on explicit identification and timing of the events and the other based on fitting the light curves with a spotted-star model. We refine the transit parameters and measure the stellar rotation period (18.5 ± 1.9 days), which corresponds to a “gyrochronological” age of 1.4 ± 0.3 Gyr. Coherent flux variations with the same period as the transits are well modeled as the combined effects of ellipsoidal light variations (15.4 ± 4.8 ppm) and Doppler boosting (14.6 ± 5.1 ppm). The magnitudes of these effects correspond to a planetary mass of 2.6+/- 0.9 {M}{Jup} and 3.9+/- 1.5 {M}{Jup}, respectively. Both of these independent mass estimates agree with the mass determined by the spectroscopic Doppler technique (2.487+/- 0.086 {M}{Jup}). No occultations are detected, giving a 2σ upper limit of 0.06 on the planet’s visual geometric albedo. We find no evidence for orbital decay, although we are only able to place a weak lower bound on the relevant tidal quality factor: {Q}\\star \\prime > 1.5× {10}4 (95% confidence).

  11. ON THE HORSESHOE DRAG OF A LOW-MASS PLANET. II. MIGRATION IN ADIABATIC DISKS

    SciTech Connect

    Masset, F. S.; Casoli, J. E-mail: jules.casoli@cea.f

    2009-09-20

    We evaluate the horseshoe drag exerted on a low-mass planet embedded in a gaseous disk, assuming the disk's flow in the co-orbital region to be adiabatic. We restrict this analysis to the case of a planet on a circular orbit, and we assume a steady flow in the corotating frame. We also assume that the corotational flow upstream of the U-turns is unperturbed, so that we discard saturation effects. In addition to the classical expression for the horseshoe drag in barotropic disks, which features the vortensity gradient across corotation, we find an additional term which scales with the entropy gradient, and whose amplitude depends on the perturbed pressure at the stagnation point of the horseshoe separatrices. This additional torque is exerted by evanescent waves launched at the horseshoe separatrices, as a consequence of an asymmetry of the horseshoe region. It has a steep dependence on the potential's softening length, suggesting that the effect can be extremely strong in the three-dimensional case. We describe the main properties of the co-orbital region (the production of vortensity during the U-turns, the appearance of vorticity sheets at the downstream separatrices, and the pressure response), and we give torque expressions suitable to this regime of migration. Side results include a weak, negative feedback on migration, due to the dependence of the location of the stagnation point on the migration rate, and a mild enhancement of the vortensity-related torque at a large entropy gradient.

  12. Fundamental Parameters Of The Lowest Mass Stars To The Highest Mass Planets

    NASA Astrophysics Data System (ADS)

    Filippazzo, Joseph C.

    2016-09-01

    The physical and atmospheric properties of ultracool dwarfs are deeply entangled due to the degenerate effects of mass, age, metallicity, clouds and dust, activity, rotation, and possibly even formation mechanism on observed spectra. Accurate determination of funda- mental parameters for a wide diversity of objects at the low end of the initial mass function (IMF) is thus crucial to testing stellar and planetary formation theories. To determine these quantities, we constructed and flux calibrated nearly-complete spectral energy distributions (SEDs) for 234 M, L, T, and Y dwarfs using published parallaxes and (0.3-40 \\mu m) spectra and photometry. From these homogeneous SEDs, we calculated bolometric luminosity ((L_\\text{bol})), effective temperature ((T_\\text{off})), mass, surface gravity, radius, spectral indexes, synthetic photometry, and bolometric corrections (BCs) for each object. We used these results to derive (L_\\text{bol}), (T_\\text{eff}), and BC polynomial relations across the entire very-low-mass star/brown dwarf/planetary mass regime. We use a subsample of objects with age constraints based on nearby young moving group membership, companionship with a young star, or spectral signatures of low surface gravity to define new age-sensitive diagnostics and characterize the reddening of young substellar atmospheres as a redistribution of flux from the near-infrared (NIR) into the mid-infrared (MIR). Consequently we find the SED flux pivots at K-band, making BCK as a function of spectral type a reliable, age-independent relationship. We find that young L dwarfs are systematically 300 K cooler than field age objects of the same spectral type and up to 600 K cooler than field age objects of the same absolute H magnitude. These findings are used to create prescriptions for the reliable and efficient characterization of new ultracool dwarfs using heterogeneous and limited spectral data.

  13. Toward a Deterministic Model of Planetary Formation. I. A Desert in the Mass and Semimajor Axis Distributions of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ida, S.; Lin, D. N. C.

    2004-03-01

    In an attempt to develop a deterministic theory for planet formation, we examine the accretion of cores of giant planets from planetesimals, gas accretion onto the cores, and their orbital migration. We adopt a working model for nascent protostellar disks with a wide variety of surface density distributions in order to explore the range of diversity among extrasolar planetary systems. We evaluate the cores' mass growth rate Mc through runaway planetesimal accretion and oligarchic growth. The accretion rate of cores is estimated with a two-body approximation. In the inner regions of disks, the cores' eccentricity is effectively damped by their tidal interaction with the ambient disk gas and their early growth is stalled by ``isolation.'' In the outer regions, the cores' growth rate is much smaller. If some cores can acquire more mass than a critical value of several Earth masses during the persistence of the disk gas, they would be able to rapidly accrete gas and evolve into gas giant planets. The gas accretion process is initially regulated by the Kelvin-Helmholtz contraction of the planets' gas envelope. Based on the assumption that the exponential decay of the disk gas mass occurs on the timescales ~106-107 yr and that the disk mass distribution is comparable to those inferred from the observations of circumstellar disks of T Tauri stars, we carry out simulations to predict the distributions of masses and semimajor axes of extrasolar planets. In disks as massive as the minimum-mass disk for the solar system, gas giants can form only slightly outside the ``ice boundary'' at a few AU. However, cores can rapidly grow above the critical mass inside the ice boundary in protostellar disks with 5 times more heavy elements than those of the minimum-mass disk. Thereafter, these massive cores accrete gas prior to its depletion and evolve into gas giants. The limited persistence of the disk gas and the decline in the stellar gravity prevent the formation of cores capable of

  14. 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.

  15. RADIO INTERFEROMETRIC PLANET SEARCH. II. CONSTRAINTS ON SUB-JUPITER-MASS COMPANIONS TO GJ 896A

    SciTech Connect

    Bower, Geoffrey C.; Bolatto, Alberto; Ford, Eric B.; Fries, Adam; Kalas, Paul; Sanchez, Karol; Viscomi, Vincent; Sanderbeck, Phoebe

    2011-10-10

    We present results from the Radio Interferometric Planet search for companions to the nearby star GJ 896A. We present 11 observations over 4.9 yr. Fitting astrometric parameters to the data reveals a residual with peak-to-peak amplitude of {approx}3 mas in right ascension. This residual is well fit by an acceleration term of 0.458 {+-} 0.032 mas yr{sup -2}. The parallax is fit to an accuracy of 0.2 mas and the proper motion terms are fit to accuracies of 0.01 mas yr{sup -1}. After fitting astrometric and acceleration terms, residuals are 0.26 mas in each coordinate, demonstrating that stellar jitter does not limit the ability to carry out radio astrometric planet detection and characterization. The acceleration term originates in part from the companion GJ 896B, but the amplitude of the acceleration in declination is not accurately predicted by the orbital model. The acceleration sets a mass upper limit of 0.15 M{sub J} at a semimajor axis of 2 AU for a planetary companion to GJ 896A. For semimajor axes between 0.3 and 2 AU upper limits are determined by the maximum angular separation; the upper limits scale from the minimum value in proportion to the inverse of the radius. Upper limits at larger radii are set by the acceleration and scale as the radius squared. An improved solution for the stellar binary system could improve the exoplanet mass sensitivity by an order of magnitude.

  16. OGLE-2016-BLG-0596Lb: A High-mass Planet from a High-magnification Pure-survey Microlensing Event

    NASA Astrophysics Data System (ADS)

    Mróz, P.; Han, C.; and; Udalski, A.; Poleski, R.; Skowron, J.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE group; Albrow, M. D.; Cha, S.-M.; Chung, S.-J.; Jung, Y. K.; Kim, D.-J.; Kim, S.-L.; Lee, C.-U.; Lee, Y.; Park, B.-G.; Pogge, R. W.; Ryu, Y.-H.; Shin, I.-G.; Yee, J. C.; Zhu, W.; Gould, A.; (KMTNet group

    2017-04-01

    We report the discovery of a high mass ratio planet, q = 0.012, i.e., 13 times higher than the Jupiter/Sun ratio. The host mass has not yet been measured but can be determined or strongly constrained from adaptive optics imaging. The planet was discovered in a small archival study of high-magnification events in pure-survey microlensing data, which was unbiased by the presence of anomalies. The fact that it was previously unnoticed may indicate that more such planets lie in archival data and could be discovered by a similar systematic study. In order to understand the transition from predominantly survey+followup to predominately survey-only planet detections, we conduct the first analysis of these detections in the observational (s, q) plane. Here s is the projected separation in units of the Einstein radius. We find some evidence that survey+followup is relatively more sensitive to planets near the Einstein ring, but that there is no statistical difference in sensitivity by mass ratio.

  17. HIGH-MASS, FOUR-PLANET CONFIGURATIONS FOR HR 8799: CONSTRAINING THE ORBITAL INCLINATION AND AGE OF THE SYSTEM

    SciTech Connect

    Sudol, Jeffrey J.; Haghighipour, Nader E-mail: nader@ifa.hawaii.edu

    2012-08-10

    Debates regarding the age and inclination of the planetary system orbiting HR 8799, and the release of additional astrometric data following the discovery of the fourth planet, prompted us to examine the possibility of constraining these two quantities by studying the long-term stability of this system at different orbital inclinations and in its high-mass configuration (7-10-10-10 M{sub Jup}). We carried out {approx}1.5 million N-body integrations for different combinations of orbital elements of the four planets. The most dynamically stable combinations survived less than {approx}5 Myr at inclinations of 0 Degree-Sign and 13 Degree-Sign , and 41, 46, and 31 Myr at 18 Degree-Sign , 23 Degree-Sign , and 30 Degree-Sign , respectively. Given such short lifetimes and the location of the system on the age-luminosity diagram for low-mass objects, the most reasonable conclusion of our study is that the planetary masses are less than 7-10-10-10 M{sub Jup} and the system is quite young. Two trends to note from our work are as follows. (1) In the most stable systems, the higher the inclination, the more the coordinates for planets b and c diverge from the oldest archival astrometric data (released after we completed our N-body integrations), suggesting that either these planets are in eccentric orbits or have lower orbital inclinations than that of planet d. (2) The most stable systems place planet e closer to the central star than is observed, supporting the conclusion that the planets are more massive and the system is young. We present the details of our simulations and discuss the implications of the results.

  18. Terrestrial planet formation in a protoplanetary disk with a local mass depletion: A successful scenario for the formation of Mars

    SciTech Connect

    Izidoro, A.; Winter, O. C.; Haghighipour, N.; Tsuchida, M. E-mail: nader@ifa.hawaii.edu

    2014-02-10

    Models of terrestrial planet formation for our solar system have been successful in producing planets with masses and orbits similar to those of Venus and Earth. However, these models have generally failed to produce Mars-sized objects around 1.5 AU. The body that is usually formed around Mars' semimajor axis is, in general, much more massive than Mars. Only when Jupiter and Saturn are assumed to have initially very eccentric orbits (e ∼ 0.1), which seems fairly unlikely for the solar system, or alternately, if the protoplanetary disk is truncated at 1.0 AU, simulations have been able to produce Mars-like bodies in the correct location. In this paper, we examine an alternative scenario for the formation of Mars in which a local depletion in the density of the protosolar nebula results in a non-uniform formation of planetary embryos and ultimately the formation of Mars-sized planets around 1.5 AU. We have carried out extensive numerical simulations of the formation of terrestrial planets in such a disk for different scales of the local density depletion, and for different orbital configurations of the giant planets. Our simulations point to the possibility of the formation of Mars-sized bodies around 1.5 AU, specifically when the scale of the disk local mass-depletion is moderately high (50%-75%) and Jupiter and Saturn are initially in their current orbits. In these systems, Mars-analogs are formed from the protoplanetary materials that originate in the regions of disk interior or exterior to the local mass-depletion. Results also indicate that Earth-sized planets can form around 1 AU with a substantial amount of water accreted via primitive water-rich planetesimals and planetary embryos. We present the results of our study and discuss their implications for the formation of terrestrial planets in our solar system.

  19. OGLE-2012-bLG-0950Lb: the First Planet Mass Measurement From Only Microlens Parallax and Lens Flux

    NASA Technical Reports Server (NTRS)

    Koshimoto, N.; Udalski, A.; Beaulieu, J. P.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Fukui, A.; Bhattacharya, A.; Suzuki, D.

    2016-01-01

    We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with a planet/host mass ratio Periapsis Approx. = 2 x10(exp. -4). A long term distortion detected in both MOA and OGLE light curve can be explained by themicrolens parallax due to the Earths orbital motion around the Sun. Although the finite source effect is not detected, we obtain the lens flux by the high resolution Keck AO observation. Combining the microlens parallax and the lens flux reveal the nature of the lens: a planet with mass of M(sub p) = 35(+17/-)M compared to Earth is orbiting around an M-dwarf with mass of M(sub host) = 0.56(+0.12/-0.16) M compared to the Sun with a planet-host projected separation of r1 = 2.7(+0.6/-0.7) au located at Luminosity Distance = 3.0(+0.8/-1.1) kpc from us. This is the first mass measurement from only microlens parallax and the lens flux without the finite source effect. In the coming space observation-era with Spitzer, K2, Euclid, and WFIRST, we expect many such events for which we will not be able to measure any finite source effect. This work demonstrates an ability of mass measurements in such events.

  20. OGLE-2012-BLG-0950Lb: The First Planet Mass Measurement from Only Microlens Parallax and Lens Flux

    NASA Astrophysics Data System (ADS)

    Koshimoto, N.; Udalski, A.; Beaulieu, J. P.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Fukui, A.; Batista, V.; Marquette, J. B.; Brillant, S.; and; Abe, F.; Asakura, Y.; Bhattacharya, A.; Donachie, M.; Freeman, M.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Matsuo, T.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Saito, To.; Sharan, A.; Shibai, H.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Kozłowski, S.; Pietrukowicz, P.; Poleski, R.; Skowron, J.; Soszyński, I.; Szymański, M. K.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration

    2017-01-01

    We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with a planet/host mass ratio of q≃ 2× {10}-4. A long term distortion detected in both MOA and OGLE light curve can be explained by the microlens parallax due to the Earth’s orbital motion around the Sun. Although the finite source effect is not detected, we obtain the lens flux by the high resolution Keck AO observation. Combining the microlens parallax and the lens flux reveal the nature of the lens: a planet with mass of {M}{{p}}={35}-9+17{M}\\oplus is orbiting around an M-dwarf with mass of {M}{host}={0.56}-0.16+0.12{M}ȯ with a planet-host projected separation of {r}\\perp ={2.7}-0.7+0.6 au located at {D}{{L}}={3.0}-1.1+0.8 kpc from us. This is the first mass measurement from only microlens parallax and the lens flux without the finite source effect. In the coming space observation-era with Spitzer, K2, Euclid, and WFIRST, we expect many such events for which we will not be able to measure any finite source effect. This work demonstrates an ability of mass measurements in such events.

  1. The GAPS Programme with HARPS-N at TNG . XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets

    NASA Astrophysics Data System (ADS)

    Bonomo, A. S.; Desidera, S.; Benatti, S.; Borsa, F.; Crespi, S.; Damasso, M.; Lanza, A. F.; Sozzetti, A.; Lodato, G.; Marzari, F.; Boccato, C.; Claudi, R. U.; Cosentino, R.; Covino, E.; Gratton, R.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Poretti, E.; Smareglia, R.; Affer, L.; Biazzo, K.; Bignamini, A.; Esposito, M.; Giacobbe, P.; Hébrard, G.; Malavolta, L.; Maldonado, J.; Mancini, L.; Martinez Fiorenzano, A.; Masiero, S.; Nascimbeni, V.; Pedani, M.; Rainer, M.; Scandariato, G.

    2017-06-01

    We carried out a Bayesian homogeneous determination of the orbital parameters of 231 transiting giant planets (TGPs) that are alone or have distant companions; we employed differential evolution Markov chain Monte Carlo methods to analyse radial-velocity (RV) data from the literature and 782 new high-accuracy RVs obtained with the HARPS-N spectrograph for 45 systems over 3 years. Our work yields the largest sample of systems with a transiting giant exoplanet and coherently determined orbital, planetary, and stellar parameters. We found that the orbital parameters of TGPs in non-compact planetary systems are clearly shaped by tides raised by their host stars. Indeed, the most eccentric planets have relatively large orbital separations and/or high mass ratios, as expected from the equilibrium tide theory. This feature would be the outcome of planetary migration from highly eccentric orbits excited by planet-planet scattering, Kozai-Lidov perturbations, or secular chaos. The distribution of α = a/aR, where a and aR are the semi-major axis and the Roche limit, for well-determined circular orbits peaks at 2.5; this agrees with expectations from the high-eccentricity migration (HEM), although it might not be limited to this migration scenario. The few planets of our sample with circular orbits and α> 5 values may have migrated through disc-planet interactions instead of HEM. By comparing circularisation times with stellar ages, we found that hot Jupiters with a< 0.05 au have modified tidal quality factors 105 ≲ Q'p ≲ 109, and that stellar Q's ≳ 106 - 107 are required to explain the presence of eccentric planets at the same orbital distance. As aby-product of our analysis, we detected a non-zero eccentricity e = 0.104-0.018+0.021 for HAT-P-29; we determined that five planets that were previously regarded to be eccentric or to have hints of non-zero eccentricity, namely CoRoT-2b, CoRoT-23b, TrES-3b, HAT-P-23b, and WASP-54b, have circular orbits or undetermined

  2. 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

  3. THE SUB-SATURN MASS TRANSITING PLANET HAT-P-12b

    SciTech Connect

    Lee, Jae Woo; Youn, Jae-Hyuck; Kim, Seung-Lee; Lee, Chung-Uk; Hinse, Tobias Cornelius E-mail: jhyoon@kasi.re.kr E-mail: leecu@kasi.re.kr

    2012-04-15

    We present new photometric data of the transiting planet HAT-P-12b observed in 2011. Our three transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law. Including our measurements, 18 transit times spanning about 4.2 yr were used to determine the improved ephemeris with a transit epoch of 2,454,187.85560 {+-} 0.00011 BJD and an orbital period of 3.21305961 {+-} 0.00000035 days. The physical properties of the star-planet system are computed using empirical calibrations from eclipsing binary stars and stellar evolutionary models, combined with both our transit parameters and previously known spectroscopic results. We found that the absolute dimensions of the host star are M{sub A} = 0.73 {+-} 0.02 M{sub Sun }, R{sub A} = 0.70 {+-} 0.01 R{sub Sun }, log g{sub A} = 4.61 {+-} 0.02, {rho}{sub A} = 2.10 {+-} 0.09 {rho}{sub Sun }, and L{sub A} = 0.21 {+-} 0.01 L{sub Sun }. The planetary companion has M{sub b} = 0.21 {+-} 0.01 M{sub Jup}, R{sub b} = 0.94 {+-} 0.01 R{sub Jup}, log g{sub b} = 2.77 {+-} 0.02, {rho}{sub b} = 0.24 {+-} 0.01 {rho}{sub Jup}, and T{sub eq} = 960 {+-} 14 K. Our results agree well with standard models of irradiated gas giants with a core mass of 11.3 M{sub Circled-Plus }.

  4. Extrasolar Planets and Prospects for Terrestrial Planets

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

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

  5. 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

  6. Low-mass Planets in Protoplanetary Disks with Net Vertical Magnetic Fields: The Planetary Wake and Gap Opening

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaohuan; Stone, James M.; Rafikov, Roman R.

    2013-05-01

    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 α 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 α 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 α-viscosity to model gaps in protoplanetary disks.

  7. Toward Eta-Earth: The Occurrences, Sizes, Orbits, Masses, and Host Stars of Planets 1-2x the Size of Earth

    NASA Astrophysics Data System (ADS)

    Borucki, William

    2013-08-01

    We propose a "Kepler Key Science" project to provide the high-resolution spectroscopic support for the Kepler Mission, during 4 semesters. We focus on KOIs having planets smaller than 2 Earth-radii to determine Teff, log g, and [Fe/H] to establish stellar and hence planet radii. We measure radial velocities with a precision of ~1.5 m/s to determine planet masses and densities, working with TTV measurements. We detect companion stars spectroscopically, to guard against false positives. Data products will be archived on the CFOP. We will determine the occurrence of Earth-size planets, and distinguish rocky from volatile-rich planets.

  8. Toward Eta-Earth: The Occurrences, Sizes, Orbits, Masses, and Host Stars of Planets 1-2x the Size of Earth

    NASA Astrophysics Data System (ADS)

    Borucki, William

    2014-02-01

    We propose a 'Kepler Key Science' project to provide the high-resolution spectroscopic support for the Kepler Mission, during 4 semesters. We focus on KOIs having planets smaller than 2 Earth-radii to determine Teff, log g, and [Fe/H] to establish stellar and hence planet radii. We measure radial velocities with a precision of ~1.5 m/s to determine planet masses and densities, working with TTV measurements. We detect companion stars spectroscopically, to guard against false positives. Data products will be archived on the CFOP. We will determine the occurrence of Earth-size planets, and distinguish rocky from volatile-rich planets.

  9. VizieR Online Data Catalog: Mass-radius relationship for planets with Rp<4 (Wolfgang+, 2016)

    NASA Astrophysics Data System (ADS)

    Wolfgang, A.; Rogers, L. A.; Ford, E. B.

    2016-08-01

    Table 2 shows all of the masses and radii that we consider, with our baseline data set denoted with a label of 0; the list was constructed by starting with the WM14 (Weiss & Marcy, 2014ApJ...783L...6W) data set and identifying new planets and updates in the NASA Exoplanet Archive (last accessed 2015 January 30). We manually double-checked each planet to verify that the reported measurements were correct. See section 3 for further details. (2 data files).

  10. The SOPHIE search for northern extrasolar planets . I. A companion around HD 16760 with mass close to the planet/brown-dwarf transition

    NASA Astrophysics Data System (ADS)

    Bouchy, F.; Hébrard, G.; Udry, S.; Delfosse, X.; Boisse, I.; Desort, M.; Bonfils, X.; Eggenberger, A.; Ehrenreich, D.; Forveille, T.; Lagrange, A. M.; Le Coroller, H.; Lovis, C.; Moutou, C.; Pepe, F.; Perrier, C.; Pont, F.; Queloz, D.; Santos, N. C.; Ségransan, D.; Vidal-Madjar, A.

    2009-10-01

    We report on the discovery of a substellar companion or a massive Jupiter orbiting the G5V star HD 16760 using the spectrograph SOPHIE installed on the OHP 1.93-m telescope. Characteristics and performances of the spectrograph are presented, as well as the SOPHIE exoplanet consortium program. With a minimum mass of 14.3 {M}_Jup, an orbital period of 465 days and an eccentricity of 0.067, HD 16760b seems to be located just at the end of the mass distribution of giant planets, close to the planet/brown-dwarf transition. Its quite circular orbit supports a formation in a gaseous protoplanetary disk. Based on observations made with SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS/OAMP), France (program 07A.PNP.CONS). Table 2 is also 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/505/853

  11. MINIMUM CORE MASSES FOR GIANT PLANET FORMATION WITH REALISTIC EQUATIONS OF STATE AND OPACITIES

    SciTech Connect

    Piso, Ana-Maria A.; Murray-Clay, Ruth A.; Youdin, Andrew N.

    2015-02-20

    Giant planet formation by core accretion requires a core that is sufficiently massive to trigger runaway gas accretion in less than the typical lifetime of protoplanetary disks. We explore how the minimum required core mass, M {sub crit}, depends on a non-ideal equation of state (EOS) and on opacity changes due to grain growth across a range of stellocentric distances from 5-100 AU. This minimum M {sub crit} applies when planetesimal accretion does not substantially heat the atmosphere. Compared to an ideal gas polytrope, the inclusion of molecular hydrogen (H{sub 2}) dissociation and variable occupation of H{sub 2} rotational states increases M {sub crit}. Specifically, M {sub crit} increases by a factor of ∼2 if the H{sub 2} spin isomers, ortho- and parahydrogen, are in thermal equilibrium, and by a factor of ∼2-4 if the ortho-to-para ratio is fixed at 3:1. Lower opacities due to grain growth reduce M {sub crit}. For a standard disk model around a Solar mass star, we calculate M {sub crit} ∼ 8 M {sub ⊕} at 5 AU, decreasing to ∼5 M {sub ⊕} at 100 AU, for a realistic EOS with an equilibrium ortho-to-para ratio and for grain growth to centimeter-sizes. If grain coagulation is taken into account, M {sub crit} may further reduce by up to one order of magnitude. These results for the minimum critical core mass are useful for the interpretation of surveys that find exoplanets at a range of orbital distances.

  12. MOA-2012-BLG-505Lb: A Super-Earth-mass Planet That Probably Resides in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Nagakane, M.; Sumi, T.; Koshimoto, N.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Suzuki, D.; Abe, F.; Asakura, Y.; Barry, R.; Bhattacharya, A.; Donachie, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Matsuo, T.; Muraki, Y.; Ohnishi, K.; Ranc, C.; Saito, To.; Sharan, A.; Shibai, H.; Sullivan, D. J.; Tristram, P. J.; Yamada, T.; Yonehara, A.; MOA Collaboration

    2017-07-01

    We report the discovery of a super-Earth-mass planet in the microlensing event MOA-2012-BLG-505. This event has the second shortest event timescale of t E = 10 ± 1 days where the observed data show evidence of a planetary companion. Our 15 minute high cadence survey observation schedule revealed the short subtle planetary signature. The system shows the well known close/wide degeneracy. The planet/host-star mass ratio is q = 2.1 × 10-4 and the projected separation normalized by the Einstein radius is s = 1.1 or 0.9 for the wide and close solutions, respectively. We estimate the physical parameters of the system by using a Bayesian analysis and find that the lens consists of a super-Earth with a mass of {6.7}-3.6+10.7 {M}\\oplus orbiting around a brown dwarf or late-M-dwarf host with a mass of {0.10}-0.05+0.16 {M}⊙ with a projected star-planet separation of {0.9}-0.2+0.3 {au}. The system is at a distance of 7.2 ± 1.1 kpc, i.e., it is likely to be in the Galactic bulge. The small angular Einstein radius (θ E = 0.12 ± 0.02 mas) and short event timescale are typical for a low-mass lens in the Galactic bulge. Such low-mass planetary systems in the Bulge are rare because the detection efficiency of planets in short microlensing events is relatively low. This discovery may suggest that such low-mass planetary systems are abundant in the Bulge and currently on-going high cadence survey programs will detect more such events and may reveal an abundance of such planetary systems.

  13. The stability of tightly-packed, evenly-spaced systems of Earth-mass planets orbiting a Sun-like star

    NASA Astrophysics Data System (ADS)

    Obertas, Alysa; Van Laerhoven, Christa; Tamayo, Daniel

    2017-09-01

    Many of the multi-planet systems discovered to date have been notable for their compactness, with neighbouring planets closer together than any in the Solar System. Interestingly, planet-hosting stars have a wide range of ages, suggesting that such compact systems can survive for extended periods of time. We have used numerical simulations to investigate how quickly systems go unstable in relation to the spacing between planets, focusing on hypothetical systems of Earth-mass planets on evenly-spaced orbits (in mutual Hill radii). In general, the further apart the planets are initially, the longer it takes for a pair of planets to undergo a close encounter. We recover the results of previous studies, showing a linear trend in the initial planet spacing between 3 and 8 mutual Hill radii and the logarithm of the stability time. Investigating thousands of simulations with spacings up to 13 mutual Hill radii reveals distinct modulations superimposed on this relationship in the vicinity of first and second-order mean motion resonances of adjacent and next-adjacent planets. We discuss the impact of this structure and the implications on the stability of compact multi-planet systems. Applying the outcomes of our simulations, we show that isolated systems of up to five Earth-mass planets can fit in the habitable zone of a Sun-like star without close encounters for at least 109 orbits.

  14. Astrometric Constraints on the Masses of Long-period Gas Giant Planets in the TRAPPIST-1 Planetary System

    NASA Astrophysics Data System (ADS)

    Boss, Alan P.; Weinberger, Alycia J.; Keiser, Sandra A.; Astraatmadja, Tri L.; Anglada-Escude, Guillem; Thompson, Ian B.

    2017-09-01

    Transit photometry of the M8V dwarf star TRAPPIST-1 (2MASS J23062928-0502285) has revealed the presence of at least seven planets with masses and radii similar to that of Earth, orbiting at distances that might allow liquid water to be present on their surfaces. We have been following TRAPPIST-1 since 2011 with the CAPSCam astrometric camera on the 2.5 m du Pont telescope at the Las Campanas Observatory in Chile. In 2016, we noted that TRAPPIST-1 lies slightly farther away than previously thought, at 12.49 pc, rather than 12.1 pc. Here, we examine 15 epochs of CAPSCam observations of TRAPPIST-1, spanning the five years from 2011 to 2016, and obtain a revised trigonometric distance of 12.56 ± 0.12 pc. The astrometric data analysis pipeline shows no evidence for a long-period astrometric wobble of TRAPPIST-1. After proper motion and parallax are removed, residuals at the level of ±1.3 mas remain. The amplitude of these residuals constrains the masses of any long-period gas giant planets in the TRAPPIST-1 system: no planet more massive than ∼4.6 M Jup orbits with a 1 year period, and no planet more massive than ∼1.6 M Jup orbits with a 5 year period. Further refinement of the CAPSCam data analysis pipeline, combined with continued CAPSCam observations, should either detect any long-period planets, or put an even tighter constraint on these mass upper limits.

  15. 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.

  16. The Lick-Carnegie exoplanet survey: Gliese 687 b—A Neptune-mass planet orbiting a nearby red dwarf

    SciTech Connect

    Burt, Jennifer; Vogt, Steven S.; Hanson, Russell; Rivera, Eugenio J.; Laughlin, Gregory; Meschiari, Stefano; Henry, Gregory W.

    2014-07-10

    Precision radial velocities from the Automated Planet Finder (APF) and Keck/HIRES reveal an Msin (i) = 18 ± 2 M{sub ⊕} planet orbiting the nearby M3V star GJ 687. This planet has an orbital period P = 38.14 days and a low orbital eccentricity. Our Strömgren b and y photometry of the host star suggests a stellar rotation signature with a period of P = 60 days. The star is somewhat chromospherically active, with a spot filling factor estimated to be several percent. The rotationally induced 60 day signal, however, is well separated from the period of the radial velocity variations, instilling confidence in the interpretation of a Keplerian origin for the observed velocity variations. Although GJ 687 b produces relatively little specific interest in connection with its individual properties, a compelling case can be argued that it is worthy of remark as an eminently typical, yet at a distance of 4.52 pc, a very nearby representative of the galactic planetary census. The detection of GJ 687 b indicates that the APF telescope is well suited to the discovery of low-mass planets orbiting low-mass stars in the as yet relatively un-surveyed region of the sky near the north celestial pole.

  17. The Lick-Carnegie Exoplanet Survey: Gliese 687 b—A Neptune-mass Planet Orbiting a Nearby Red Dwarf

    NASA Astrophysics Data System (ADS)

    Burt, Jennifer; Vogt, Steven S.; Butler, R. Paul; Hanson, Russell; Meschiari, Stefano; Rivera, Eugenio J.; Henry, Gregory W.; Laughlin, Gregory

    2014-07-01

    Precision radial velocities from the Automated Planet Finder (APF) and Keck/HIRES reveal an Msin (i) = 18 ± 2 M ⊕ planet orbiting the nearby M3V star GJ 687. This planet has an orbital period P = 38.14 days and a low orbital eccentricity. Our Strömgren b and y photometry of the host star suggests a stellar rotation signature with a period of P = 60 days. The star is somewhat chromospherically active, with a spot filling factor estimated to be several percent. The rotationally induced 60 day signal, however, is well separated from the period of the radial velocity variations, instilling confidence in the interpretation of a Keplerian origin for the observed velocity variations. Although GJ 687 b produces relatively little specific interest in connection with its individual properties, a compelling case can be argued that it is worthy of remark as an eminently typical, yet at a distance of 4.52 pc, a very nearby representative of the galactic planetary census. The detection of GJ 687 b indicates that the APF telescope is well suited to the discovery of low-mass planets orbiting low-mass stars in the as yet relatively un-surveyed region of the sky near the north celestial pole.

  18. 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

  19. 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

  20. 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.

  1. Five Planets Transiting a Ninth Magnitude Star

    NASA Astrophysics Data System (ADS)

    Vanderburg, Andrew; Becker, Juliette C.; Kristiansen, Martti H.; Bieryla, Allyson; Duev, Dmitry A.; Jensen-Clem, Rebecca; Morton, Timothy D.; Latham, David W.; Adams, Fred C.; Baranec, Christoph; Berlind, Perry; Calkins, Michael L.; Esquerdo, Gilbert A.; Kulkarni, Shrinivas; Law, Nicholas M.; Riddle, Reed; Salama, Maïssa; Schmitt, Allan R.

    2016-08-01

    The Kepler mission has revealed a great diversity of planetary systems and architectures, but most of the planets discovered by Kepler orbit faint stars. Using new data from the K2 mission, we present the discovery of a five-planet system transiting a bright (V = 8.9, K = 7.7) star called HIP 41378. HIP 41378 is a slightly metal-poor late F-type star with moderate rotation (v sin i ≃ 7 {km} {{{s}}}-1) and lies at a distance of 116 ± 18 pc from Earth. We find that HIP 41378 hosts two sub-Neptune-sized planets orbiting 3.5% outside a 2:1 period commensurability in 15.6 and 31.7 day orbits. In addition, we detect three planets that each transit once during the 75 days spanned by K2 observations. One planet is Neptune-sized in a likely ˜160 day orbit, one is sub-Saturn-sized, likely in a ˜130 day orbit, and one is a Jupiter-sized planet in a likely ˜1 year orbit. We show that these estimates for the orbital periods can be made more precise by taking into account dynamical stability considerations. We also calculate the distribution of stellar reflex velocities expected for this system, and show that it provides a good target for future radial velocity observations. If a precise orbital period can be determined for the outer Jovian planets through future observations, this system will be an excellent candidate for follow-up transit observations to study its atmosphere and measure its oblateness.

  2. On-sky Doppler performance of TOU optical very high-resolution spectrograph for detecting low-mass planets

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Ma, Bo; Sithajan, Sirinrat; Singer, Michael A.; Powell, Scott; Varosi, Frank; Zhao, Bo; Schofield, Sidney; Liu, Jian; Grieves, Nolan; Cassette, Anthony; Avner, Louis; Jakeman, Hali; Muterspaugh, Matthew; Williamson, Michael; Barnes, Rory

    2016-08-01

    The TOU robotic, compact very high resolution optical spectrograph (R=100,000, 0.38-0.9 microns) has been fully characterized at the 2 meter Automatic Spectroscopy Telescope (AST) at Fairborn Observatory in Arizona during its pilot survey of 12 bright FGK dwarfs in 2015. This instrument has delivered sub m/s Doppler precision for bright reference stars (e.g., 0.7 m/s for Tau Ceti over 60 days) with 5-30 min exposures and 0.7 m/s long-term instrument stability, which is the best performance among all of the known Doppler spectrographs to our knowledge. This performance was achieved by maintaining the instrument in a very high vacuum of 1 micron torr and about 0.5 mK (RMS) long-term temperature stability through an innovative close-loop instrument bench temperature control. It has discovered a 21 Earth-mass planet (P=43days) around a bright K dwarf and confirmed three super-Earth planetary systems, HD 1461, 190360 and HD 219314. This instrument will be used to conduct the Dharma Planet Survey (DPS) in 2016-2019 to monitor 100 nearby very bright FGK dwarfs (most of them brighter than V=8) at the dedicated 50-inch Robotic Telescope on Mt. Lemmon. With very high RV precision and high cadence ( 100 observations per target randomly spread over 450 days), a large number of rocky planets, including possible habitable ones, are expected to be detected. The survey also provides the largest single homogenous high precision RV sample of nearby stars for studying low mass planet populations and constraining various planet formation models. Instrument on-sky performance is summarized.

  3. Confirming the transit of the Earth-mass planet orbiting Alpha Centauri B

    NASA Astrophysics Data System (ADS)

    Demory, Brice-Olivier

    2013-10-01

    One of the most fascinating exoplanet findings of the past years is undoubtedly the discovery of an Earth-mass exoplanet orbiting Alpha Centauri B. Alpha Cen Bb orbits one component of the closest stellar system to the Earth and has the potential to become a true Rosetta stone in exoplanet science, if its transiting nature were revealed. In 2013, we observed Alpha Centauri B during 16 orbits with HST/STIS to search for the transit of Alpha Cen Bb. We recently carried out in-depth photometric analyses of this dataset that resulted in the clear detection of a transit-shaped pattern. Several factors, however, prevent us from securing the planetary nature of the signal found in the STIS time-series. Now that we know where and when to look for, we propose to confirm the repeatability of this signal and to firmly establish Alpha Cen Bb's existence and tighten its physical and orbital properties. We base our observing strategy on the successful approach employed just one year ago with the same instrument. Until Aug 9th 2014, combination of HST available roll angles, Alpha Cen binary separation and position angle will match the nearly-ideal configuration we had in July 2013. It would even be possible to benefit from CVZ status from 24/7/2014 to 28/7/2014, in which one transit of Alpha Centauri Bb is expected. HST/STIS is the only facility able to confirm a transit from such a small planet at a high confidence level.

  4. THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE

    SciTech Connect

    Barman, Travis S.; Macintosh, Bruce; Konopacky, Quinn M.; Marois, Christian

    2011-07-10

    The properties of 2M1207b, a young ({approx}8 Myr) planet-mass companion, have lacked a satisfactory explanation for some time. The combination of low luminosity, red near-IR colors, and L-type near-IR spectrum (previously consistent with T{sub eff} {approx} 1600 K) implies an abnormally small radius. Early explanations for the apparent underluminosity of 2M1207b invoked an edge-on disk or the remnant of a recent protoplanetary collision. The discovery of a second planet-mass object (HR8799b) with similar luminosity and colors as 2M1207b indicates that a third explanation, one of a purely atmospheric nature, is more likely. By including clouds, non-equilibrium chemistry, and low gravity, an atmosphere with effective temperature consistent with evolution cooling-track predictions is revealed. Consequently, 2M1207b, and others like it, requires no new physics to explain nor do they belong to a new class of objects. Instead they most likely represent the natural extension of cloudy substellar atmospheres down to low T{sub eff} and log (g). If this atmosphere only explanation for 2M1207b is correct, then very young planet-mass objects with near-IR spectra similar to field T dwarfs may be rare.

  5. The Effect of Population-wide Mass-to-radius Relationships on the Interpretation of Kepler and HARPS Super-Earth Occurrence Rates

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Laughlin, Gregory

    2012-05-01

    planets, while Kepler detects a large population of gaseous sub-Neptunes.

  6. THE EFFECT OF POPULATION-WIDE MASS-TO-RADIUS RELATIONSHIPS ON THE INTERPRETATION OF KEPLER AND HARPS SUPER-EARTH OCCURRENCE RATES

    SciTech Connect

    Wolfgang, Angie; Laughlin, Gregory

    2012-05-10

    detecting a large population of dense low-mass planets, while Kepler detects a large population of gaseous sub-Neptunes.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

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

  9. Planet formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1993-01-01

    Models of planetary formation are developed using the present single example of a planetary system, supplemented by limited astrophysical observations of star-forming regions and circumstellar disks. The solar nebula theory and the planetesimal hypothesis are discussed. The latter is found to provide a viable theory of the growth of the terrestrial planets, the cores of the giant planets, and the smaller bodies present in the solar system. The formation of solid bodies of planetary size should be a common event, at least around young stars which do not have binary companions orbiting at planetary distances. Stochastic impacts of large bodies provide sufficient angular momentum to produce the obliquities of the planets. The masses and bulk compositions of the planets can be understood in a gross sense as resulting from planetary growth within a disk whose temperature and surface density decreased with distance from the growing sun.

  10. Planet or brown dwarf? Inferring the companion mass in HD 100546 from the wall shape using mid-infrared interferometry

    NASA Astrophysics Data System (ADS)

    Mulders, Gijs D.; Paardekooper, Sijme-Jan; Panić, Olja; Dominik, Carsten; van Boekel, Roy; Ratzka, Thorsten

    2013-09-01

    Context. Giant planets form in protoplanetary disks while these disks are still gas-rich, and can reveal their presence through the annular gaps they carve out. HD 100546 is a gas-rich disk with a wide gap between a radius of ~1 and 13 AU, possibly cleared out by a planetary companion or planetary system. Aims: We aim to identify the nature of the unseen companion near the far end of the disk gap. Methods: We used mid-infrared interferometry at multiple baselines to constrain the curvature of the disk wall at the far end of the gap. We used 2D hydrodynamical simulations of embedded planets and brown dwarfs to estimate the viscosity of the disk and the mass of a companion close to the disk wall. Results: We find that the disk wall at the far end of the gap is not vertical, but rounded-off by a gradient in the surface density. This gradient can be reproduced in hydrodynamical simulations with a single, heavy companion (≳30...80 MJup) while the disk has a viscosity of at least α ≳ 5 × 10-3. Taking into account the changes in the temperature structure after gap opening reduces the lower limit on the planet mass and disk viscosity to 20 MJup and α = 2 × 10-3. Conclusions: The object in the disk gap of HD 100546 that shapes the disk wall is most likely a 60+20-40 MJup brown dwarf, while the disk viscosity is estimated to be at least α = 2 × 10-3. The disk viscosity is an important factor in estimating planetary masses from disk morphologies: more viscous disks need heavier planets to open an equally deep gap.

  11. Finding Earth clones with SIM: The most promising near-term technique to detect, find masses for, and determine three-dimensional orbits of nearby habitable planets

    NASA Astrophysics Data System (ADS)

    Shao, Michael; Unwin, Stephen C.; Beichman, Charles; Catanzarite, Joseph; Edberg, Stephen J.; Marr, James C., IV; Marcy, Geoffrey

    2007-09-01

    SIM is a space astrometric interferometer capable of better than one-microarcsecond ( as) single measurement accuracy, providing the capability to detect stellar "wobble" resulting from planets in orbit around nearby stars. While a search for exoplanets can be optimized in a variety of ways, a SIM five-year search optimized to detect Earth analogs (0.3 to 10 Earth masses) in the middle of the habitable zone (HZ) of nearby stars would yield the masses, without M*sin(i) ambiguity, and three-dimensional orbital parameters for planets around ~70 stars, including those in the HZ and further away from those same stars. With >200 known planets outside our solar system, astrophysical theorists have built numerical models of planet formation that match the distribution of Jovian planets discovered to date and those models predict that the number of terrestrial planets (< 10 M (+) ) would far exceed the number of more massive Jovian planets. Even so, not every star will have an Earth analog in the middle of its HZ. This paper describes the relationship between SIM and other planet detection methods, the SIM planet observing program, expected results, and the state of technical readiness for the SIM mission.

  12. 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.

  13. MINERVA-Red: A telescope dedicated to the discovery of planets orbiting the nearest low-mass stars

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Results from Kepler and ground-based exoplanet surveys suggest that M-dwarfs host numerous small sized planets. Additionally, the discovery of the Earth-sized exoplanets orbiting Proxima Centauri and Trappist 1 demonstrate that these stars can host terrestrial planets in their habitable zones. Since low-mass stars are intrinsically faint at optical wavelengths, obtaining 1 m/s Doppler resolution to detect their planetary companions remains a challenge for instruments designed for sun-like stars. We describe a novel, high-cadence approach aimed at detecting and characterizing planets orbiting the closest low-mass stars to the Sun. MINERVA-Red is an echelle spectrograph optimized for the 'deep red', between 800 nm and 900 nm, where M-dwarfs are brightest. The spectrograph will be temperature controlled at 20C +/- 10mk and in a vacuum chamber which maintains a pressure below 0.01 mbar while using a Fabry-Perot etalon and U/Ne lamp for wavelength calibration. The spectrometer will operate with a robotic, 0.7-meter telescope at Mt. Hopkins, Arizona. We expect first light in 2017.

  14. THE AGE OF THE HD 15407 SYSTEM AND THE EPOCH OF FINAL CATASTROPHIC MASS ACCRETION ONTO TERRESTRIAL PLANETS AROUND SUN-LIKE STARS

    SciTech Connect

    Melis, C.; Zuckerman, B.; Rhee, Joseph H.; Song, Inseok

    2010-07-01

    From optical spectroscopic measurements we determine that the HD 15407 binary system is {approx}80 Myr old. The primary star, HD 15407A (spectral type F5 V), exhibits strong mid-infrared excess emission indicative of a recent catastrophic collision between rocky planetary embryos or planets in its inner planetary system. The synthesis of all known stars with large quantities of dust in their terrestrial planet zone indicates that for stars of roughly solar mass this warm dust phenomenon occurs at ages between 30 and 100 Myr. In contrast, for stars of a few solar masses, the dominant era of the final assembling of rocky planets occurs earlier, between 10 and 30 Myr age. The incidence of the warm dust phenomenon, when compared against models for the formation of rocky terrestrial-like bodies, implies that rocky planet formation in the terrestrial planet zone around Sun-like stars is common.

  15. MOA 2010-BLG-477Lb: CONSTRAINING THE MASS OF A MICROLENSING PLANET FROM MICROLENSING PARALLAX, ORBITAL MOTION, AND DETECTION OF BLENDED LIGHT

    SciTech Connect

    Bachelet, E.; Fouque, P.; Shin, I.-G.; Han, C.; Gould, A.; Dong, Subo; Marshall, J.; Skowron, J.; Menzies, J. W.; Beaulieu, J.-P.; Marquette, J.-B.; Bennett, D. P.; Bond, I. A.; Heyrovsky, D.; Street, R. A.; Sumi, T.; Udalski, A.; Abe, L.; Agabi, K.; Albrow, M. D.; Collaboration: PLANET Collaboration; FUN muCollaboration; MOA Collaboration; OGLE Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; and others

    2012-07-20

    Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA 2010-BLG-477. The measured planet-star mass ratio is q = (2.181 {+-} 0.004) Multiplication-Sign 10{sup -3} and the projected separation is s = 1.1228 {+-} 0.0006 in units of the Einstein radius. The angular Einstein radius is unusually large {theta}{sub E} = 1.38 {+-} 0.11 mas. Combining this measurement with constraints on the 'microlens parallax' and the lens flux, we can only limit the host mass to the range 0.13 < M/M{sub Sun} < 1.0. In this particular case, the strong degeneracy between microlensing parallax and planet orbital motion prevents us from measuring more accurate host and planet masses. However, we find that adding Bayesian priors from two effects (Galactic model and Keplerian orbit) each independently favors the upper end of this mass range, yielding star and planet masses of M{sub *} = 0.67{sup +0.33}{sub -0.13} M{sub Sun} and m{sub p} = 1.5{sup +0.8}{sub -0.3} M{sub JUP} at a distance of D = 2.3 {+-} 0.6 kpc, and with a semi-major axis of a = 2{sup +3}{sub -1} AU. Finally, we show that the lens mass can be determined from future high-resolution near-IR adaptive optics observations independently from two effects, photometric and astrometric.

  16. OGLE-2012-BLG-0563Lb: A Saturn-mass Planet around an M Dwarf with the Mass Constrained by Subaru AO Imaging

    NASA Astrophysics Data System (ADS)

    Fukui, A.; Gould, A.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Han, C.; Suzuki, D.; Beaulieu, J.-P.; Batista, V.; Udalski, A.; Street, R. A.; Tsapras, Y.; Hundertmark, M.; Abe, F.; Bhattacharya, A.; Freeman, M.; Itow, Y.; Ling, C. H.; Koshimoto, N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Ohnishi, K.; Philpott, L. C.; Rattenbury, N.; Saito, T.; Sullivan, D. J.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Choi, J.-Y.; Christie, G. W.; DePoy, D. L.; Dong, Subo; Drummond, J.; Gaudi, B. S.; Hwang, K.-H.; Kavka, A.; Lee, C.-U.; McCormick, J.; Natusch, T.; Ngan, H.; Park, H.; Pogge, R. W.; Shin, I.-G.; Tan, T.-G.; Yee, J. C.; μFUN Collaboration; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Bramich, D. M.; Browne, P.; Dominik, M.; Horne, K.; Ipatov, S.; Kains, N.; Snodgrass, C.; Steele, I. A.; RoboNet Collaboration

    2015-08-01

    We report the discovery of a microlensing exoplanet OGLE-2012-BLG-0563Lb with the planet-star mass ratio of ˜ 1× {10}-3. Intensive photometric observations of a high-magnification microlensing event allow us to detect a clear signal of the planet. Although no parallax signal is detected in the light curve, we instead succeed at detecting the flux from the host star in high-resolution JHK‧-band images obtained by the Subaru/AO188 and Infrared Camera and Spectrograph instruments, allowing us to constrain the absolute physical parameters of the planetary system. With the help of spectroscopic information about the source star obtained during the high-magnification state by Bensby et al., we find that the lens system is located at 1.3{}-0.8+0.6 kpc from us, and consists of an M dwarf (0.34 {}-0.20+0.12M{}⊙ ) orbited by a Saturn-mass planet (0.39 {}-0.23+0.14MJup) at the projected separation of 0.74{}-0.42+0.26 AU (close model) or 4.3{}-2.5+1.5 AU (wide model). The probability of contamination in the host star’s flux, which would reduce the masses by a factor of up to three, is estimated to be 17%. This possibility can be tested by future high-resolution imaging. We also estimate the (J-{K}{{s}}) and (H-{K}{{s}}) colors of the host star, which are marginally consistent with a low metallicity mid-to-early M dwarf, although further observations are required for the metallicity to be conclusive. This is the fifth sub-Jupiter-mass (0.2\\lt {m}{{p}}/{M}{Jup}\\lt 1) microlensing planet around an M dwarf with the mass well constrained. The relatively rich harvest of sub-Jupiters around M dwarfs is contrasted with a possible paucity of ˜1-2 Jupiter-mass planets around the same type of star, which can be explained by the planetary formation process in the core-accretion scheme.

  17. Embedded Protostellar Disks Around (Sub-)Solar Stars. II. Disk Masses, Sizes, Densities, Temperatures, and the Planet Formation Perspective

    NASA Astrophysics Data System (ADS)

    Vorobyov, Eduard I.

    2011-03-01

    We present basic properties of protostellar disks in the embedded phase of star formation (EPSF), which is difficult to probe observationally using available observational facilities. We use numerical hydrodynamics simulations of cloud core collapse and focus on disks formed around stars in the 0.03-1.0 M sun mass range. Our obtained disk masses scale near-linearly with the stellar mass. The mean and median disk masses in the Class 0 and I phases (M mean d,C0 = 0.12 M sun, M mdn d,C0 = 0.09 M sun and M mean d,CI = 0.18 M sun, M mdn d,CI = 0.15 M sun, respectively) are greater than those inferred from observations by (at least) a factor of 2-3. We demonstrate that this disagreement may (in part) be caused by the optically thick inner regions of protostellar disks, which do not contribute to millimeter dust flux. We find that disk masses and surface densities start to systematically exceed that of the minimum mass solar nebular for objects with stellar mass as low as M * = 0.05-0.1 M sun. Concurrently, disk radii start to grow beyond 100 AU, making gravitational fragmentation in the disk outer regions possible. Large disk masses, surface densities, and sizes suggest that giant planets may start forming as early as in the EPSF, either by means of core accretion (inner disk regions) or direct gravitational instability (outer disk regions), thus breaking a longstanding stereotype that the planet formation process begins in the Class II phase.

  18. DEUTERIUM BURNING IN MASSIVE GIANT PLANETS AND LOW-MASS BROWN DWARFS FORMED BY CORE-NUCLEATED ACCRETION

    SciTech Connect

    Bodenheimer, Peter; Fortney, Jonathan J.; Saumon, Didier E-mail: gennaro.dangelo@nasa.gov E-mail: jfortney@ucolick.org

    2013-06-20

    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{sub Circled-Plus }, are assumed to accrete gas up to final masses of 10-15 Jupiter masses (M{sub 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{sub 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{sub 50} fall in the range 11.6-13.6 M{sub 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{sub 50}. For masses above M{sub 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.

  19. Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere . The impact on stellar and planetary mass

    NASA Astrophysics Data System (ADS)

    Sousa, S. G.; Santos, N. C.; Mortier, A.; Tsantaki, M.; Adibekyan, V.; Delgado Mena, E.; Israelian, G.; Rojas-Ayala, B.; Neves, V.

    2015-04-01

    Aims: In this work we derive new precise and homogeneous parameters for 37 stars with planets. For this purpose, we analyze high resolution spectra obtained by the NARVAL spectrograph for a sample composed of bright planet host stars in the northern hemisphere. The new parameters are included in the SWEET-Cat online catalogue. Methods: To ensure that the catalogue is homogeneous, we use our standard spectroscopic analysis procedure, ARES+MOOG, to derive effective temperatures, surface gravities, and metallicities. These spectroscopic stellar parameters are then used as input to compute the stellar mass and radius, which are fundamental for the derivation of the planetary mass and radius. Results: We show that the spectroscopic parameters, masses, and radii are generally in good agreement with the values available in online databases of exoplanets. There are some exceptions, especially for the evolved stars. These are analyzed in detail focusing on the effect of the stellar mass on the derived planetary mass. Conclusions: We conclude that the stellar mass estimations for giant stars should be managed with extreme caution when using them to compute the planetary masses. We report examples within this sample where the differences in planetary mass can be as high as 100% in the most extreme cases. Based on observations obtained at the Telescope Bernard Lyot (USR5026) operated by the Observatoire Midi-Pyrénées and the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France (Run ID L131N11 - OPTICON_2013A_027).

  20. 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.

  1. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  2. ON SHOCKS DRIVEN BY HIGH-MASS PLANETS IN RADIATIVELY INEFFICIENT DISKS. II. THREE-DIMENSIONAL GLOBAL DISK SIMULATIONS

    SciTech Connect

    Lyra, Wladimir; Richert, Alexander J. W.; Boley, Aaron; Turner, Neal; Okuzumi, Satoshi; Flock, Mario; Mac Low, Mordecai-Mark E-mail: neal.j.turner@jpl.nasa.gov E-mail: ajr327@psu.edu E-mail: mordecai@amnh.org

    2016-02-01

    Recent high-resolution, near-infrared images of protoplanetary disks have shown that these disks often present spiral features. Spiral arms are among the structures predicted by models of disk–planet interaction and thus it is tempting to suspect that planetary perturbers are responsible for these signatures. However, such interpretation is not free of problems. The observed spirals have large pitch angles, and in at least one case (HD 100546) it appears effectively unpolarized, implying thermal emission of the order of 1000 K (465 ± 40 K at closer inspection). We have recently shown in two-dimensional models that shock dissipation in the supersonic wake of high-mass planets can lead to significant heating if the disk is sufficiently adiabatic. Here we extend this analysis to three dimensions in thermodynamically evolving disks. We use the Pencil Code in spherical coordinates for our models, with a prescription for thermal cooling based on the optical depth of the local vertical gas column. We use a 5M{sub J} planet, and show that shocks in the region around the planet where the Lindblad resonances occur heat the gas to substantially higher temperatures than the ambient gas. The gas is accelerated vertically away from the midplane to form shock bores, and the gas falling back toward the midplane breaks up into a turbulent surf. This turbulence, although localized, has high α values, reaching 0.05 in the inner Lindblad resonance, and 0.1 in the outer one. We find evidence that the disk regions heated up by the shocks become superadiabatic, generating convection far from the planet’s orbit.

  3. HAT-P-26b: A Low-density Neptune-mass Planet Transiting a K Star

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Kipping, D. M.; Torres, G.; Kovács, G.; Noyes, R. W.; Latham, D. W.; Howard, A. W.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Isaacson, H.; Quinn, S. N.; Buchhave, L. A.; Béky, B.; Sasselov, D. D.; Stefanik, R. P.; Esquerdo, G. A.; Everett, M.; Perumpilly, G.; Lázár, J.; Papp, I.; Sári, P.

    2011-02-01

    We report the discovery of HAT-P-26b, a transiting extrasolar planet orbiting the moderately bright V = 11.744 K1 dwarf star GSC 0320-01027, with a period P = 4.234516 ± 0.000015 days, transit epoch Tc = 2455304.65122 ± 0.00035 (BJD; Barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1023 ± 0.0010 days. The host star has a mass of 0.82 ± 0.03 M sun, radius of 0.79+0.10 -0.04 R sun, effective temperature 5079 ± 88 K, and metallicity [Fe/H] = -0.04 ± 0.08. The planetary companion has a mass of 0.059 ± 0.007 M J, and radius of 0.565+0.072 -0.032 R J yielding a mean density of 0.40 ± 0.10 g cm-3. HAT-P-26b is the fourth Neptune-mass transiting planet discovered to date. It has a mass that is comparable to those of Neptune and Uranus, and slightly smaller than those of the other transiting Super-Neptunes, but a radius that is ~65% larger than those of Neptune and Uranus, and also larger than those of the other transiting Super-Neptunes. HAT-P-26b is consistent with theoretical models of an irradiated Neptune-mass planet with a 10 M ⊕ heavy element core that comprises gsim50% of its mass with the remainder contained in a significant hydrogen-helium envelope, though the exact composition is uncertain as there are significant differences between various theoretical models at the Neptune-mass regime. The equatorial declination of the star makes it easily accessible to both Northern and Southern ground-based facilities for follow-up observations. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NASA (N018Hr and N167Hr).

  4. 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

  5. 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

  6. 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.

  7. Kepler Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2015-01-01

    Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

  8. RETIRED A STARS AND THEIR COMPANIONS. III. COMPARING THE MASS-PERIOD DISTRIBUTIONS OF PLANETS AROUND A-TYPE STARS AND SUN-LIKE STARS

    SciTech Connect

    Bowler, Brendan P.; Johnson, John Asher; Liu, Michael C.; Marcy, Geoffrey W.; Peek, Kathryn M. G.; Henry, Gregory W.; Fischer, Debra A.; Clubb, Kelsey I.; Reffert, Sabine; Schwab, Christian; Lowe, Thomas B.

    2010-01-20

    We present an analysis of approx5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 approx< M{sub *}/M{sub sun}approx< 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26{sup +9}{sub -8}%, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to left brace0.2, 0.3, 0.5, 0.6, 1.3right brace M{sub Jup} within left brace0.1, 0.3, 0.6, 1.0, 3.0right brace AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN propor to M {sup a}lpha P {sup b}eta dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of alpha and beta for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4sigma level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (approx50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets.

  9. STELLAR PARAMETERS FOR HD 69830, A NEARBY STAR WITH THREE NEPTUNE MASS PLANETS AND AN ASTEROID BELT

    SciTech Connect

    Tanner, Angelle; Boyajian, Tabetha S.; Brewer, John M.; Fischer, Debra; Von Braun, Kaspar; Van Belle, Gerard T.; Kane, Stephen; Farrington, Chris; Brummelaar, Theo A. ten; McAlister, Harold A.; Schaefer, Gail; Beichman, Charles A.

    2015-02-20

    We used the CHARA Array to directly measure the angular diameter of HD 69830, home to three Neptune mass planets and an asteroid belt. Our measurement of 0.674 ± 0.014 mas for the limb-darkened angular diameter of this star leads to a physical radius of R {sub *} = 0.9058 ± 0.0190 R {sub ☉} and luminosity of L {sub *} = 0.622 ± 0.014 L {sub ☉} when combined with a fit to the spectral energy distribution of the star. Placing these observed values on an Hertzsprung-Russel diagram along with stellar evolution isochrones produces an age of 10.6 ± 4 Gyr and mass of 0.863 ± 0.043 M {sub ☉}. We use archival optical echelle spectra of HD 69830 along with an iterative spectral fitting technique to measure the iron abundance ([Fe/H] = –0.04 ± 0.03), effective temperature (5385 ± 44 K), and surface gravity (log g = 4.49 ± 0.06). We use these new values for the temperature and luminosity to calculate a more precise age of 7.5 ± 3 Gyr. Applying the values of stellar luminosity and radius to recent models on the optimistic location of the habitable zone produces a range of 0.61-1.44 AU; partially outside the orbit of the furthest known planet (d) around HD 69830. Finally, we estimate the snow line at a distance of 1.95 ± 0.19 AU, which is outside the orbit of all three planets and its asteroid belt.

  10. Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Tanner, Angelle; Boyajian, Tabetha S.; von Braun, Kaspar; Kane, Stephen; Brewer, John M.; Farrington, Chris; van Belle, Gerard T.; Beichman, Charles A.; Fischer, Debra; ten Brummelaar, Theo A.; McAlister, Harold A.; Schaefer, Gail

    2015-02-01

    We used the CHARA Array to directly measure the angular diameter of HD 69830, home to three Neptune mass planets and an asteroid belt. Our measurement of 0.674 ± 0.014 mas for the limb-darkened angular diameter of this star leads to a physical radius of R * = 0.9058 ± 0.0190 R ⊙ and luminosity of L * = 0.622 ± 0.014 L ⊙ when combined with a fit to the spectral energy distribution of the star. Placing these observed values on an Hertzsprung-Russel diagram along with stellar evolution isochrones produces an age of 10.6 ± 4 Gyr and mass of 0.863 ± 0.043 M ⊙. We use archival optical echelle spectra of HD 69830 along with an iterative spectral fitting technique to measure the iron abundance ([Fe/H] = -0.04 ± 0.03), effective temperature (5385 ± 44 K), and surface gravity (log g = 4.49 ± 0.06). We use these new values for the temperature and luminosity to calculate a more precise age of 7.5 ± 3 Gyr. Applying the values of stellar luminosity and radius to recent models on the optimistic location of the habitable zone produces a range of 0.61-1.44 AU partially outside the orbit of the furthest known planet (d) around HD 69830. Finally, we estimate the snow line at a distance of 1.95 ± 0.19 AU, which is outside the orbit of all three planets and its asteroid belt.

  11. 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.

  12. 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.

  13. THE LICK-CARNEGIE EXOPLANET SURVEY: A SATURN-MASS PLANET IN THE HABITABLE ZONE OF THE NEARBY M4V STAR HIP 57050

    SciTech Connect

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

    2010-05-20

    Precision radial velocities (RV) from Keck/HIRES reveal a Saturn-mass planet orbiting the nearby M4V star HIP 57050. The planet has a minimum mass of Msin i {approx} 0.3 M{sub J}, an orbital period of 41.4 days, and an orbital eccentricity of 0.31. V-band photometry reveals a clear stellar rotation signature of the host star with a period of 98 days, well separated from the period of the RV variations and reinforcing a Keplerian origin for the observed velocity variations. The orbital period of this planet corresponds to an orbit in the habitable zone of HIP 57050, with an expected planetary temperature of {approx}230 K. The star has a metallicity of [Fe/H] = 0.32 {+-} 0.06 dex, of order twice solar and among the highest metallicity stars in the immediate solar neighborhood. This newly discovered planet provides further support that the well-known planet-metallicity correlation for F, G, and K stars also extends down into the M-dwarf regime. The a priori geometric probability for transits of this planet is only about 1%. However, the expected eclipse depth is {approx}7%, considerably larger than that yet observed for any transiting planet. Though long on the odds, such a transit is worth pursuing as it would allow for high quality studies of the atmosphere via transmission spectroscopy with Hubble Space Telescope. At the expected planetary effective temperature, the atmosphere may contain water clouds.

  14. KELT-10b and KELT-11b: Two Sub-Jupiter Mass Planets well-Suited for Atmospheric Characterization in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Rodriguez, Joseph E.

    2015-12-01

    The Kilodegree Extremely Little Telescope (KELT) project is a photometric survey in both the northern and southern hemispheres for transiting planets around bright stars (8 < V < 11), and has discovered 15 planets to date. Of these, several possess unique characteristics that make them especially well suited for study of planet atmospheres. Here, I present the first two discoveries from the KELT-South survey. KELT-10b is an inflated transiting sub-Jupiter mass planet (0.68 MJ) around a V=10.7 early G-star. It has the 3rd deepest transit (1.4%) in the southern hemisphere for a star V < 12.5, making it a great target for transmission spectroscopy. KELT-11b is a highly inflated transiting Saturn mass planet (0.22 MJ) orbiting one of the brightest planet-hosting stars in the southern hemisphere. Interestingly, KELT-11b's host star is a clear sub-giant star (log(g) ~ 3.7). I will discuss their impact for atmospheric characterization. For example, the highly inflated nature of the KELT-11b planet provides the ability to study a sub-Jupiter atmosphere at very low planetary gravity, while the sub-giant nature of its host star allows us to study the effects of post main sequence evolution of a host star on a hot Jupiter.

  15. The CRIRES Search for Planets Around the Lowest-Mass Stars: High-Precision nIR Radial Velocities with a New Gas Cell

    NASA Astrophysics Data System (ADS)

    Seifahrt, Andreas; Bean, J.; Hartman, H.; Nilsson, H.; Wiedemann, G.; Reiners, A.; Dreizler, S.; Henry, T.

    2010-01-01

    We are currently carrying out a search for planets around the lowest-mass stars using the CRIRES instrument at the VLT under the auspices of an ESO Large Programme. The main purposes of this work are to illuminate the correlation between stellar mass and planet formation, improve the census of planets, and identify new planets that can be followed-up for detailed study. We have developed, and are utilizing a new type of gas cell for obtaining high-precision radial velocities of late-type stars in the nIR spectral region. Observations in the nIR offer the advantages in that the targeted stars are bright enough for high-precision spectroscopy, and that the noise contribution from stellar activity is significantly reduced. We will describe the new gas cell and our radial velocity measurement algorithm, and present extensive tests of the obtained precision.

  16. HAT-P-28b AND HAT-P-29b: TWO SUB-JUPITER MASS TRANSITING PLANETS

    SciTech Connect

    Buchhave, L. A.; Bakos, G. A.; Hartman, J. D.; Torres, G.; Latham, D. W.; Noyes, R. W.; Esquerdo, G. A.; Beky, B.; Sasselov, D. D.; Furesz, G.; Quinn, S. N.; Stefanik, R. P.; Szklenar, T.; Andersen, J.; Kovacs, G.; Shporer, A.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.

    2011-06-01

    We present the discovery of two transiting exoplanets. HAT-P-28b orbits a V = 13.03 G3 dwarf star with a period P = 3.2572 days and has a mass of 0.63 {+-} 0.04 M{sub J} and a radius of 1.21{sup +0.11}{sub -0.08} R{sub J} yielding a mean density of 0.44 {+-} 0.09 g cm{sup -3}. HAT-P-29b orbits a V = 11.90 F8 dwarf star with a period P = 5.7232 days and has a mass of 0.78{sup +0.08}{sub -0.04} M{sub J} and a radius of 1.11{sup +0.14}{sub -0.08} R{sub J} yielding a mean density of 0.71 {+-} 0.18 g cm{sup -3}. We discuss the properties of these planets in the context of other known transiting planets.

  17. Indication of a massive circumbinary planet orbiting the low-mass X-ray binary MXB 1658-298

    NASA Astrophysics Data System (ADS)

    Jain, Chetana; Paul, Biswajit; Sharma, Rahul; Jaleel, Abdul; Dutta, Anjan

    2017-06-01

    We present an X-ray timing analysis of the transient X-ray binary MXB 1658-298, using data obtained from the RXTE and XMM-Newton observatories. We have made 27 new mid-eclipse time measurements from observations made during the two outbursts of the source. These new measurements have been combined with the previously known values to study long-term changes in orbital period of the binary system. We have found that the mid-eclipse timing record of MXB 1658-298 is quite unusual. The long-term evolution of mid-eclipse times indicates an overall orbital period decay with a time-scale of -6.5(7) × 107 yr. Over and above this orbital period decay, the O-C residual curve also shows a periodic residual on shorter time-scales. This sinusoidal variation has an amplitude of ˜9 lt-s and a period of ˜760 d. This is indicative of the presence of a third body around the compact X-ray binary. The mass and orbital radius of the third body are estimated to lie in the ranges 20.5-26.9 Jupiter mass and 750-860 lt-s, respectively. If true, then it will be the most massive circumbinary planet and also the smallest period binary known to host a planet.

  18. Testing Planet Formation Models with Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ford, E. B.

    The first discoveries of extrasolar planets demonstrated that nature produces a much greater diversity of planetary systems than astronomers had anticipated. In an attempt to explain these surprises, theorists have proposed numerous generalizations to the classical model of planet formation. Recently, researchers have begun testing some of these theories by comparing the predicted distributions of planet periods, eccentricities, and masses to those of the observed population of extrasolar planets. Such comparisons are becoming increasingly powerful thanks to the increasing number of known planets, improving measurement precision, increasing temporal baselines, and improving capability to control for detection biases. Here, we discuss some of the orbital properties of the extrasolar planet population based on a systematic analysis of radial velocity planets and discuss implications for the formation and evolution of planetary systems.

  19. Spitzer as a Microlens Parallax Satellite: Mass Measurement for the OGLE-2014-BLG-0124L Planet and its Host Star

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Yee, J. C.; Gould, A.; Carey, S.; Zhu, W.; Skowron, J.; Kozłowski, S.; Poleski, R.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Mróz, P.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Han, C.; Calchi Novati, S.; Pogge, R. W.

    2015-02-01

    We combine Spitzer and ground-based observations to measure the microlens parallax vector {\\boldsymbol {π }}_E, and thus the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. The planet and star have masses of m ~ 0.5 M jup and M ~ 0.7 M ⊙ and are separated by a ~ 3.1 AU in projection. The main source of uncertainty in all of these numbers (approximately 30%, 30%, and 20%) is the relatively poor measurement of the Einstein radius θE, rather than uncertainty in πE, which is measured with 2.5% precision. This compares to 22% based on OGLE data alone, implying that the Spitzer data provide not only a substantial improvement in the precision of the πE measurement, but also the first independent test of a ground-based {\\boldsymbol {π }}_E measurement.

  20. A First-look Atmospheric Modeling Study of the Young Directly Imaged Planet-mass Companion, ROXs 42Bb

    NASA Astrophysics Data System (ADS)

    Currie, Thayne; Burrows, Adam; Daemgen, Sebastian

    2014-06-01

    We present and analyze JKsL' photometry and our previously published H-band photometry and K-band spectroscopy for ROXs 42Bb, an object Currie et al. first reported as a young directly imaged planet-mass companion. ROXs 42Bb exhibits IR colors redder than field L dwarfs but consistent with other planet-mass companions. From the H2O-2 spectral index, we estimate a spectral type of L0 ± 1; weak detections/non-detections of the CO bandheads, Na I, and Ca I support evidence for a young, low surface gravity object primarily derived from the H2(K) index. ROXs 42Bb's photometry/K-band spectrum are inconsistent with limiting cases of dust-free atmospheres (COND) and marginally inconsistent with the AMES/DUSTY models and the BT-SETTL models. However, ROXS 42Bb data are simultaneously fit by atmosphere models incorporating several micron-sized dust grains entrained in thick clouds, although further modifications are needed to better reproduce the K-band spectral shape. ROXs 42Bb's best-estimated temperature is T eff ~ 1950-2000 K, near the low end of the empirically derived range in Currie et al. For an age of ~1-3 Myr and considering the lifetime of the protostar phase, ROXs 42Bb's luminosity of log(L/L ⊙) ~ -3.07 ± 0.07 implies a mass of 9^{+3}_{-3} MJ , making it one of the lightest planetary-mass objects yet imaged.

  1. A first-look atmospheric modeling study of the young directly imaged planet-mass companion, ROXS 42Bb

    SciTech Connect

    Currie, Thayne; Daemgen, Sebastian; Burrows, Adam

    2014-06-01

    We present and analyze JK{sub s}L' photometry and our previously published H-band photometry and K-band spectroscopy for ROXs 42Bb, an object Currie et al. first reported as a young directly imaged planet-mass companion. ROXs 42Bb exhibits IR colors redder than field L dwarfs but consistent with other planet-mass companions. From the H{sub 2}O-2 spectral index, we estimate a spectral type of L0 ± 1; weak detections/non-detections of the CO bandheads, Na I, and Ca I support evidence for a young, low surface gravity object primarily derived from the H{sub 2}(K) index. ROXs 42Bb's photometry/K-band spectrum are inconsistent with limiting cases of dust-free atmospheres (COND) and marginally inconsistent with the AMES/DUSTY models and the BT-SETTL models. However, ROXS 42Bb data are simultaneously fit by atmosphere models incorporating several micron-sized dust grains entrained in thick clouds, although further modifications are needed to better reproduce the K-band spectral shape. ROXs 42Bb's best-estimated temperature is T {sub eff} ∼ 1950-2000 K, near the low end of the empirically derived range in Currie et al. For an age of ∼1-3 Myr and considering the lifetime of the protostar phase, ROXs 42Bb's luminosity of log(L/L {sub ☉}) ∼ –3.07 ± 0.07 implies a mass of 9{sub −3}{sup +3} M{sub J} , making it one of the lightest planetary-mass objects yet imaged.

  2. Characterizing Transiting Planets with JWST Spectra: Simulations and Retrievals

    NASA Technical Reports Server (NTRS)

    Greene, Tom; Line, Michael; Fortney, Jonathan

    2015-01-01

    There are now well over a thousand confirmed exoplanets, ranging from hot to cold and large to small worlds. JWST spectra will provide much more detailed information on the molecular constituents, chemical compositions, and thermal properties of the atmospheres of transiting planets than is now known. We explore this by modeling clear, cloudy,and high mean molecular weight atmospheres of typical hot Jupiter, warm Neptune, warm sub-Neptune, and cool super-Earth planets and then simulating their JWST transmission and emission spectra. These simulations were performed for several JWST instrument modes over 1 - 11 microns and incorporate realistic signal and noise components. We then performed state-of the art retrievals to determine how well temperatures and abundances (CO, CO2, H2O, NH3) will be constrained and over what pressures for these different planet types. Using these results, we appraise what instrument modes will be most useful for determining what properties of the different planets, and we assess how well we can constrain their compositions, CO ratios, and temperature profiles.

  3. SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs. I. New atmospheric parameters and masses for 48 stars with planets

    NASA Astrophysics Data System (ADS)

    Santos, N. C.; Sousa, S. G.; Mortier, A.; Neves, V.; Adibekyan, V.; Tsantaki, M.; Delgado Mena, E.; Bonfils, X.; Israelian, G.; Mayor, M.; Udry, S.

    2013-08-01

    Context. Thanks to the importance that the star-planet relation has to our understanding of the planet formation process, the precise determination of stellar parameters for the ever increasing number of discovered extra-solar planets is of great relevance. Furthermore, precise stellar parameters are needed to fully characterize the planet properties. It is thus important to continue the efforts to determine, in the most uniform way possible, the parameters for stars with planets as new discoveries are announced. Aims: In this paper we present new precise atmospheric parameters for a sample of 48 stars with planets. We then take the opportunity to present a new catalogue of stellar parameters for FGK and M stars with planets detected by radial velocity, transit, and astrometry programs. Methods: Stellar atmospheric parameters and masses for the 48 stars were derived assuming local thermodynamic equilibrium (LTE) and using high-resolution and high signal-to-noise spectra. The methodology used is based on the measurement of equivalent widths for a list of iron lines and making use of iron ionization and excitation equilibrium principles. For the catalogue, and whenever possible, we used parameters derived in previous works published by our team, using well-defined methodologies for the derivation of stellar atmospheric parameters. This set of parameters amounts to over 65% of all planet host stars known, including more than 90% of all stars with planets discovered through radial velocity surveys. For the remaining targets, stellar parameters were collected from the literature. Results: The stellar parameters for the 48 stars are presented and compared with previously determined literature values. For the catalogue, we compile values for the effective temperature, surface gravity, metallicity, and stellar mass for almost all the planet host stars listed in the Extrasolar Planets Encyclopaedia. This data will be updated on a continuous basis. The compiled catalogue is

  4. PHOTOMETRICALLY DERIVED MASSES AND RADII OF THE PLANET AND STAR IN THE TrES-2 SYSTEM

    SciTech Connect

    Barclay, Thomas; Huber, Daniel; Rowe, Jason F.; Quintana, Elisa V.; Christiansen, Jessie L.; Jenkins, Jon M.; Mullally, Fergal; Seader, Shaun E.; Tenenbaum, Peter; Thompson, Susan E.; Barentsen, Geert; Bloemen, Steven; Demory, Brice-Olivier; Fulton, Benjamin J.; Shporer, Avi; Ragozzine, Darin

    2012-12-10

    We measure the mass and radius of the star and planet in the TrES-2 system using 2.7 years of observations by the Kepler spacecraft. The light curve shows evidence for ellipsoidal variations and Doppler beaming on a period consistent with the orbital period of the planet with amplitudes of 2.79{sup +0.44}{sub -0.62} and 3.44{sup +0.32}{sub -0.37} parts per million (ppm), respectively, and a difference between the dayside and the nightside planetary flux of 3.41{sup +0.55}{sub -0.82} ppm. We present an asteroseismic analysis of solar-like oscillations on TrES-2A which we use to calculate the stellar mass of 0.94 {+-} 0.05 M{sub Sun} and radius of 0.95 {+-} 0.02 R{sub Sun }. Using these stellar parameters, a transit model fit and the phase-curve variations, we determine the planetary radius of 1.162{sup +0.020}{sub -0.024} R{sub Jup} and derive a mass for TrES-2b from the photometry of 1.44 {+-} 0.21 M{sub Jup}. The ratio of the ellipsoidal variation to the Doppler beaming amplitudes agrees to better than 2{sigma} with theoretical predications, while our measured planet mass and radius agree within 2{sigma} of previously published values based on spectroscopic radial velocity measurements. We measure a geometric albedo of 0.0136{sup +0.0022}{sub -0.0033} and an occultation (secondary eclipse) depth of 6.5{sup +1.7}{sub -1.8} ppm which we combined with the day/night planetary flux ratio to model the atmosphere of TrES-2b. We find that an atmosphere model that contains a temperature inversion is strongly preferred. We hypothesize that the Kepler bandpass probes a significantly greater atmospheric depth on the night side relative to the day side.

  5. MICROLENS TERRESTRIAL PARALLAX MASS MEASUREMENTS: A RARE PROBE OF ISOLATED BROWN DWARFS AND FREE-FLOATING PLANETS

    SciTech Connect

    Gould, Andrew; Yee, Jennifer C. E-mail: jyee@astronomy.ohio-state.edu

    2013-02-10

    Terrestrial microlens parallax is one of the very few methods that can measure the mass and number density of isolated dark low-mass objects, such as old free-floating planets and brown dwarfs. Terrestrial microlens parallax can be measured whenever a microlensing event differs substantially as observed from two or more well-separated sites. If the lens also transits the source during the event, then its mass can be measured. We derive an analytic expression for the expected rate of such events and then use this to derive two important conclusions. First, the rate is directly proportional to the number density of a given population, greatly favoring low-mass populations relative to their contribution to the general microlensing rate, which further scales as M {sup 1/2} where M is the lens mass. Second, the rate rises sharply as one probes smaller source stars, despite the fact that the probability of transit falls directly with source size. We propose modifications to current observing strategies that could yield a factor of 100 increase in sensitivity to these rare events.

  6. Microlens Terrestrial Parallax Mass Measurements: A Rare Probe of Isolated Brown Dwarfs and Free-floating Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Yee, Jennifer C.

    2013-02-01

    Terrestrial microlens parallax is one of the very few methods that can measure the mass and number density of isolated dark low-mass objects, such as old free-floating planets and brown dwarfs. Terrestrial microlens parallax can be measured whenever a microlensing event differs substantially as observed from two or more well-separated sites. If the lens also transits the source during the event, then its mass can be measured. We derive an analytic expression for the expected rate of such events and then use this to derive two important conclusions. First, the rate is directly proportional to the number density of a given population, greatly favoring low-mass populations relative to their contribution to the general microlensing rate, which further scales as M 1/2 where M is the lens mass. Second, the rate rises sharply as one probes smaller source stars, despite the fact that the probability of transit falls directly with source size. We propose modifications to current observing strategies that could yield a factor of 100 increase in sensitivity to these rare events.

  7. ASTROMETRY AND RADIAL VELOCITIES OF THE PLANET HOST M DWARF GJ 317: NEW TRIGONOMETRIC DISTANCE, METALLICITY, AND UPPER LIMIT TO THE MASS OF GJ 317b

    SciTech Connect

    Anglada-Escude, Guillem; Boss, Alan P.; Weinberger, Alycia J.; Butler, R. Paul; Thompson, Ian B.; Vogt, Steven S.; Rivera, Eugenio J.

    2012-02-10

    We have obtained precision astrometry of the planet host M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. The resulting absolute magnitudes suggest that it is metal-rich and more massive than previously assumed. This result strengthens the correlation between high metallicity and the presence of gas giants around low-mass stars. At 15.3 pc, the minimal astrometric amplitude for planet candidate GJ 317b is 0.3 mas (edge-on orbit), just below our astrometric sensitivity. However, given the relatively large number of observations and good astrometric precision, a Bayesian Monte Carlo Markov Chain analysis indicates that the mass of planet b has to be smaller than twice the minimum mass with a 99% confidence level, with a most likely value of 2.5 M{sub Jup}. Additional radial velocity (RV) measurements obtained with Keck by the Lick-Carnegie Planet search program confirm the presence of an additional very long period planet candidate, with a period of 20 years or more. Even though such an object will imprint a large astrometric wobble on the star, its curvature is yet not evident in the astrometry. Given high metallicity, and the trend indicating that multiple systems are rich in low-mass companions, this system is likely to host additional low-mass planets in its habitable zone that can be readily detected with state-of-the-art optical and near-infrared RV measurements.

  8. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Technical Reports Server (NTRS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.

    2016-01-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 +/- 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B and C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of an approximately 4-9 Gyr lens star of M(sub lens) = 1.06 +/- 0.05 solar mass at a distance of D(sub lens) = 4.0 +/- 0.3 kpc, orbited by two giant planets of 0.145 +/- 0.008 M(sub Jup) and 0.86 +/- 0.06 M(sub Jup), with projected separations of 4.0 +/- 0.5 au and 4.8 +/- 0.7 au, respectively. Because the lens is brighter than the source star by 16 +/- 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  9. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Technical Reports Server (NTRS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.

    2016-01-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 +/- 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B and C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of an approximately 4-9 Gyr lens star of M(sub lens) = 1.06 +/- 0.05 solar mass at a distance of D(sub lens) = 4.0 +/- 0.3 kpc, orbited by two giant planets of 0.145 +/- 0.008 M(sub Jup) and 0.86 +/- 0.06 M(sub Jup), with projected separations of 4.0 +/- 0.5 au and 4.8 +/- 0.7 au, respectively. Because the lens is brighter than the source star by 16 +/- 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  10. Observsational Planet Formation

    NASA Astrophysics Data System (ADS)

    Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

    2017-06-01

    Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

  11. Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Bhattacharya, A.; Anderson, J.; Bond, I. A.; Anderson, N.; Barry, R.; Batista, V.; Beaulieu, J.-P.; DePoy, D. L.; Dong, Subo; Gaudi, B. S.; Gilbert, E.; Gould, A.; Pfeifle, R.; Pogge, R. W.; Suzuki, D.; Terry, S.; Udalski, A.

    2015-08-01

    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of {M}*=0.69+/- 0.02{M}⊙ and {m}{{p}}=14.1+/- 0.9{M}\\oplus . The planetary microlens system is located toward the Galactic bulge at a distance of {D}L=4.1+/- 0.4 kpc and the projected star-planet separation is {a}\\perp =3.5+/- 0.3 AU, corresponding to a semimajor axis of a={4.0}-0.6+2.2 AU.

  12. Climate and Water Contents on Rocky Planets Near the Inner Boundary of Habitable Zones (IHZ) Around Low Mass Star

    NASA Astrophysics Data System (ADS)

    Bin, Jiayu; Tian, Feng

    2017-04-01

    Exoplanets around low mass stars are the focus of the search for habitable exoplanets. Previous general circulation models (GCM) studied the locations of the IHZ around stars with effective temperature from 3300 to 4500K (Yang et al. 2014, Kopparapu et al. 2016). However, water vapor mixing ratios at 3 hPa pressure level do not satisfy what is required for scenarios of rapid water loss in the "last converged solution" for stars cooler than 4000 K. In this work we use the Community Earth System Model (CESM) to investigate the IHZ problem for low mass stars. The model includes atmospheres with 1 bar of N2, 1 ppm of CO2, and slab oceans with thermodynamic sea ice. Rotation period is determined by the mass and luminosity of the star and planet orbital distance. Black body spectra of low mass stars are used to obtain top-of-atmosphere incident short wavelength radiation. Our model results are qualitatively consistent but quantitatively different from those in earlier works. Specifically, water vapor mixing ratios required by rapid water loss are found at 3 hPa for hosts star warmer than 3650 K.

  13. Microlensing Constraints on the Frequency of Jupiter-Mass Companions: Analysis of 5 Years of PLANET Photometry

    NASA Astrophysics Data System (ADS)

    Gaudi, B. S.; Albrow, M. D.; An, J.; Beaulieu, J.-P.; Caldwell, J. A. R.; DePoy, D. L.; Dominik, M.; Gould, A.; Greenhill, J.; Hill, K.; Kane, S.; Martin, R.; Menzies, J.; Naber, R. M.; Pel, J.-W.; Pogge, R. W.; Pollard, K. R.; Sackett, P. D.; Sahu, K. C.; Vermaak, P.; Vreeswijk, P. M.; Watson, R.; Williams, A.

    2002-02-01

    We analyze 5 years of PLANET photometry of microlensing events toward the Galactic bulge to search for the short-duration deviations from single-lens light curves that are indicative of the presence of planetary companions to the primary microlenses. Using strict event-selection criteria, we construct a well-defined sample of 43 intensively monitored events. We search for planetary perturbations in these events over a densely sampled region of parameter space spanning two decades in mass ratio and projected separation, but find no viable planetary candidates. By combining the detection efficiencies of the events, we find that, at 95% confidence, less than 25% of our primary lenses have companions with mass ratio q=10-2 and separations in the lensing zone, [0.6-1.6]θE, where θE is the Einstein ring radius. Using a model of the mass, velocity, and spatial distribution of bulge lenses, we infer that the majority of our lenses are likely M dwarfs in the Galactic bulge. We conclude that less than 33% of M dwarfs in the Galactic bulge have companions with mass mp=MJ between 1.5 and 4 AU, and less than 45% have companions with mp=3MJ between 1 and 7 AU, the first significant limits on planetary companions to M dwarfs. We consider the effects of the finite size of the source stars and changing our detection criterion, but find that these do not alter our conclusions substantially.

  14. Advanced Ion Mass spectrometer for Giant Planet Ionospheres, Magnetospheres and Moons

    NASA Astrophysics Data System (ADS)

    Sittler, E. C.; Cooper, J. F.; Paschalidis, N.; Jones, S. L.; Brinckerhoff, W. L.; Paterson, W. R.; Ali, A.; Coplan, M. A.; Chornay, D.; Sturner, S. J.; Benna, M.; Bateman, F. B.; Fontaine, D.; Verdeil, C.; Andre, N.; Blanc, M.; Wurz, P.

    2016-10-01

    Advanced Ion Mass Spectrometer is being developed to measure both major and minor ion species from 1 V to 25 kV with wide field-of-view in the 1-60 amu mass range at M/ΔM ≤ 60 over a wide range of ion intensities within high radiation environments.

  15. Triaxial deformation and asynchronous rotation of rocky planets in the habitable zone of low-mass stars

    NASA Astrophysics Data System (ADS)

    Zanazzi, J. J.; Lai, Dong

    2017-08-01

    Rocky planets orbiting M-dwarf stars in the habitable zone tend to be driven to synchronous rotation by tidal dissipation, potentially causing difficulties for maintaining a habitable climate on the planet. However, the planet may be captured into asynchronous spin-orbit resonances, and this capture may be more likely if the planet has a sufficiently large intrinsic triaxial deformation. We derive the analytic expression for the maximum triaxiality of a rocky planet, with and without a liquid envelope, as a function of the planet's radius, density, rigidity and critical strain of fracture. The derived maximum triaxiality is consistent with the observed triaxialities for terrestrial planets in the Solar system, and indicates that rocky planets in the habitable zone of M-dwarfs can in principle be in a state of asynchronous spin-orbit resonances.

  16. Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Tanner, Angelle M.; Boyajian, T. S.; von Braun, K.; van Belle, G.; Beichman, C. A.; Fischer, D.; Brewer, J. M.; GSU CHARA Team

    2014-01-01

    We have used the GSU CHARA telescope to directly measure the diameter of HD 69830, home to three Neptune mass planets and an asteroid belt. Our estimate for the limb-darkened angular diameter of this star leads to its physical radius and luminosity when combined with a fit to its observed optical to infrared spectral energy distribution. With precise values of the luminosity and effective temperature, we can then place HD 69830 on an HR diagram along with isochrones from the latest stellar formation models to determine the age of the star. Finally, the new value of stellar luminosity also leads to a refined estimate of the location of the habitable zone and the ice line for HD 69830. In this poster, we will report the newly determined stellar parameters for this high profile star and discuss how they influence our knowledge of the properties of its solar system.

  17. Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c

    NASA Astrophysics Data System (ADS)

    Jones, M. I.; Jenkins, J. S.; Rojo, P.; Olivares, F.; Melo, C. H. F.

    2015-08-01

    Context. Precision radial velocities are required to discover and characterize exoplanets. Optical spectra that exhibit many hundreds of absorption lines can allow the m s-1 precision levels required for this work. After the main-sequence, intermediate-mass stars expand and rotate more slowly than their progenitors, thus, thousands of spectral lines appear in the optical region, permitting the search for Doppler signals in these types of stars. Aims: In 2009, we began the EXPRESS program, aimed at detecting substellar objects around evolved stars, and studying the effects of the mass and evolution of the host star on their orbital and physical properties. Methods: We obtained precision radial velocity measurements for the giant stars HIP 65891 and HIP 107773, from CHIRON and FEROS spectra. Also, we obtained new radial velocity epochs for the star HIP 67851, which is known to host a planetary system. Results: We present the discovery of two giant planets around the intermediate-mass evolved star HIP 65891 and HIP 107773. The best Keplerian fit to the HIP 65891 and HIP 107773 radial velocities leads to the following orbital parameters: P = 1084.5 d; mb sini = 6.0 MJ ; e = 0.13 and P = 144.3 d; mb sini = 2.0 MJ ; e = 0.09, respectively. In addition, we confirm the planetary nature of the outer object orbiting the giant star HIP 67851. The orbital parameters of HIP 67851 c are: P = 2131.8 d, mc sini = 6.0MJ, and e = 0.17. Conclusions: With masses of 2.5 M⊙ and 2.4 M⊙, HIP 65891 and HIP 107773 are two of the most massive planet-hosting stars. Additionally, HIP 67851 is one of five giant stars that are known to host a planetary system having a close-in planet (a< 0.7 AU). Based on the evolutionary states of those five stars, we conclude that close-in planets do exist in multiple systems around subgiants and slightly evolved giants stars, but most likely they are subsequently destroyed by the stellar envelope during the ascent of the red giant branch phase. Based on

  18. Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

    NASA Astrophysics Data System (ADS)

    Gandolfi, D.; Parviainen, H.; Deeg, H. J.; Lanza, A. F.; Fridlund, M.; Prada Moroni, P. G.; Alonso, R.; Augusteijn, T.; Cabrera, J.; Evans, T.; Geier, S.; Hatzes, A. P.; Holczer, T.; Hoyer, S.; Kangas, T.; Mazeh, T.; Pagano, I.; Tal-Or, L.; Tingley, B.

    2015-04-01

    We report the spectroscopic confirmation of the Kepler object of interest KOI-183.01 (Kepler-423b), a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1-17) with high-precision radial velocity measurements taken with the FIES spectrograph at the Nordic Optical Telescope. We simultaneously modelled the photometric and spectroscopic data-sets using Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that the Kepler pre-search data conditioned light curve of Kepler-423 exhibits quarter-to-quarter systematic variations of the transit depth, with a peak-to-peak amplitude of ~4.3% and seasonal trends reoccurring every four quarters. We attributed these systematics to an incorrect assessment of the quarterly variation of the crowding metric. The host star Kepler-423 is a G4 dwarf with M⋆ = 0.85 ± 0.04 M⊙, R⋆ = 0.95 ± 0.04 R⊙, Teff= 5560 ± 80 K, [M/H] = - 0.10 ± 0.05 dex, and with an age of 11 ± 2 Gyr. The planet Kepler-423b has a mass of Mp= 0.595 ± 0.081MJup and a radius of Rp= 1.192 ± 0.052RJup, yielding a planetary bulk density of ρp = 0.459 ± 0.083 g cm-3. The radius of Kepler-423b is consistent with both theoretical models for irradiated coreless giant planets and expectations based on empirical laws. The inclination of the stellar spin axis suggests that the system is aligned along the line of sight. We detected a tentative secondary eclipse of the planet at a 2σ confidence level (ΔFec = 14.2 ± 6.6 ppm) and found that the orbit might have asmall non-zero eccentricity of 0.019+0.028-0.014. With a Bond albedo of AB = 0.037 ± 0.019, Kepler-423b is one of the gas-giant planets with the lowest albedo known so far. Based on observations obtained with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of

  19. OGLE-2015-BLG-0051/KMT-2015-BLG-0048Lb: A Giant Planet Orbiting a Low-mass Bulge Star Discovered by High-cadence Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Bozza, V.; Jung, Y. K.; Albrow, M. D.; Kim, S.-L.; Lee, C.-U.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; Park, B.-G.; Shin, I.-G.; KMTNet Collaboration; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE Collaboration

    2016-10-01

    We report the discovery of an extrasolar planet detected from the combined data of a microlensing event OGLE-2015-BLG-0051/KMT-2015-BLG-0048 acquired by two microlensing surveys. Despite the fact that the short planetary signal occurred in the very early Bulge season during which the lensing event could be seen for just about an hour, the signal was continuously and densely covered. From the Bayesian analysis using models of the mass function, and matter and velocity distributions, combined with information on the angular Einstein radius, it is found that the host of the planet is located in the Galactic bulge. The planet has a mass {0.72}-0.07+0.65 {M}{{J}} and it is orbiting a low-mass M-dwarf host with a projected separation {d}\\perp =0.73+/- 0.08 {{au}}. The discovery of the planet demonstrates the capability of the current high-cadence microlensing lensing surveys in detecting and characterizing planets.

  20. Dynamical mass measurement of the young spectroscopic binary V343 Normae AaAb resolved with the Gemini Planet Imager

    DOE PAGES

    Nielsen, Eric L.; De Rosa, Robert J.; Wang, Jason; ...

    2016-11-22

    Here, we present new spatially resolved astrometry and photometry from the Gemini Planet Imager of the inner binary of the young multiple star system V343 Normae, which is a member of the β Pictoris (β Pic) moving group. V343 Normae comprises a K0 and mid-M star in a ~4.5 year orbit (AaAb) and a wide 10'' M5 companion (B). By combining these data with archival astrometry and radial velocities we fit the orbit and measure individual masses for both components ofmore » $${M}_{\\mathrm{Aa}}=1.10\\pm 0.10\\,{M}_{\\odot }$$ and $${M}_{\\mathrm{Ab}}=0.290\\pm 0.018\\,{M}_{\\odot }$$. Comparing to theoretical isochrones, we find good agreement for the measured masses and JHK band magnitudes of the two components consistent with the age of the β Pic moving group. We derive a model-dependent age for the β Pic moving group of 26 ± 3 Myr by combining our results for V343 Normae with literature measurements for GJ 3305, which is another group member with resolved binary components and dynamical masses.« less

  1. High-Contrast 3.8 Micron Imaging of the Brown Dwarf/Planet-Mass Companion to GJ 758

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Bailey, Vanessa; Fabrycky, Daniel; Murray-Clay, Ruth; Rodigas, Timothy; Hinz, Phil

    2010-01-01

    We present L' band (3.8 Micron) MMT/Clio high-contrast imaging data for the nearby star GJ 758, which was recently reported by Thalmann et al. (2009) to have one -- possibly two-- faint comoving companions (GJ 7588 and "C", respectively). GJ 758B is detected in two distinct datasets. Additionally, we report a \\textit(possible) detection of the object identified by Thalmann et al as "GJ 758C" in our more sensitive dataset, though it is likely a residual speckle. However, if it is the same object as that reported by Thalmann et al. it cannot be a companion in a bound orbit. GJ 758B has a H-L'color redder than nearly all known L--T8 dwarfs. Based on comparisons with the COND evolutionary models, GJ 758B has Te approx. 560 K (+150 K, -90 K) and a mass ranging from approx. 10-20 Mj if it is approx. 1 Gyr old to approx. 25-40 Mj if it is 8.7 Gyr old. GJ 758B is likely in a highly eccentric orbit, e approx. 0.73 (+0.12,-0.21), with a semimajor axis of approx. 44 AU (+32 AU, -14 AU). Though GJ 758B is sometimes discussed within the context of exoplanet direct imaging, its mass is likely greater than the deuterium-burning limit and its formation may resemble that of binary stars rather than that of jovian-mass planets.

  2. High-Contrast 3.8 Micron Imaging of the Brown Dwarf/Planet-Mass Companion to GJ 758

    NASA Technical Reports Server (NTRS)

    Currie, Thayne M.; Bailey, Vanessa; Fabrycky, Daniel; Murray-Clay, Ruth; Rodigas, Timothy; Hinz, Phil

    2011-01-01

    We present L' band (3.8 Micron) MMT/Clio high-contrast imaging data for the nearby star GJ 758, which was recently reported by Thalmann et al. (2009) to have one - possibly two - faint comoving companions (GJ 7588 and "C", respectively). GJ 758B is detected in two distinct datasets. Additionally, we report a \\textit{possible} detection of the object identified by Thalmann et al as "GJ 758C" in our more sensitive dataset, though it is likely a residual speckle. However, if it is the same object as that reported by Thalmann et al. it cannot be a companion in a bound orbit. GJ 7588 has a H-L' color redder than nearly all known L-T8 dwarfs. 8ased on comparisons with the COND evolutionary models, GJ 7588 has Te approx. 560 K (+150 K, -90 K) and a mass ranging from approx.10-20 Mj if it is approx.1 Gyr old to approx. 25-40 Mj if it is 8.7 Gyr old. GJ 7588 is likely in a highly eccentric orbit, e approx. 0.73 (+0.12,-0.21), with a semimajor axis of approx. 44 AU (+32 AU, -14 AU). Though GJ 7588 is sometimes discussed within the context of exoplanet direct imaging, its mass is likely greater than the deuterium-burning limit and its formation may resemble that of binary stars rather than that of jovian-mass planets.

  3. High-Contrast 3.8 Micron Imaging of the Brown Dwarf/Planet-Mass Companion to GJ 758

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Bailey, Vanessa; Fabrycky, Daniel; Murray-Clay, Ruth; Rodigas, Timothy; Hinz, Phil

    2010-01-01

    We present L' band (3.8 Micron) MMT/Clio high-contrast imaging data for the nearby star GJ 758, which was recently reported by Thalmann et al. (2009) to have one -- possibly two-- faint comoving companions (GJ 7588 and "C", respectively). GJ 758B is detected in two distinct datasets. Additionally, we report a \\textit(possible) detection of the object identified by Thalmann et al as "GJ 758C" in our more sensitive dataset, though it is likely a residual speckle. However, if it is the same object as that reported by Thalmann et al. it cannot be a companion in a bound orbit. GJ 758B has a H-L'color redder than nearly all known L--T8 dwarfs. Based on comparisons with the COND evolutionary models, GJ 758B has Te approx. 560 K (+150 K, -90 K) and a mass ranging from approx. 10-20 Mj if it is approx. 1 Gyr old to approx. 25-40 Mj if it is 8.7 Gyr old. GJ 758B is likely in a highly eccentric orbit, e approx. 0.73 (+0.12,-0.21), with a semimajor axis of approx. 44 AU (+32 AU, -14 AU). Though GJ 758B is sometimes discussed within the context of exoplanet direct imaging, its mass is likely greater than the deuterium-burning limit and its formation may resemble that of binary stars rather than that of jovian-mass planets.

  4. Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric L.; De Rosa, Robert J.; Wang, Jason; Rameau, Julien; Song, Inseok; Graham, James R.; Macintosh, Bruce; Ammons, Mark; Bailey, Vanessa P.; Barman, Travis S.; Bulger, Joanna; Chilcote, Jeffrey K.; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Katherine B.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn M.; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Oppenheimer, Rebecca; Palmer, David W.; Patience, Jenny; Perrin, Marshall D.; Poyneer, Lisa A.; Pueyo, Laurent; Rajan, Abhijith; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2016-12-01

    We present new spatially resolved astrometry and photometry from the Gemini Planet Imager of the inner binary of the young multiple star system V343 Normae, which is a member of the β Pictoris (β Pic) moving group. V343 Normae comprises a K0 and mid-M star in a ˜4.5 year orbit (AaAb) and a wide 10″ M5 companion (B). By combining these data with archival astrometry and radial velocities we fit the orbit and measure individual masses for both components of {M}{Aa}=1.10+/- 0.10 {M}⊙ and {M}{Ab}=0.290+/- 0.018 {M}⊙ . Comparing to theoretical isochrones, we find good agreement for the measured masses and JHK band magnitudes of the two components consistent with the age of the β Pic moving group. We derive a model-dependent age for the β Pic moving group of 26 ± 3 Myr by combining our results for V343 Normae with literature measurements for GJ 3305, which is another group member with resolved binary components and dynamical masses.

  5. Dynamical mass measurement of the young spectroscopic binary V343 Normae AaAb resolved with the Gemini Planet Imager

    SciTech Connect

    Nielsen, Eric L.; De Rosa, Robert J.; Wang, Jason; Rameau, Julien; Song, Inseok; Graham, James R.; Macintosh, Bruce; Ammons, Mark; Bailey, Vanessa P.; Barman, Travis S.; Bulger, Joanna; Chilcote, Jeffrey K.; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Follette, Katherine B.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li -Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn M.; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Oppenheimer, Rebecca; Palmer, David W.; Patience, Jenny; Perrin, Marshall D.; Poyneer, Lisa A.; Pueyo, Laurent; Rajan, Abhijith; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2016-11-22

    Here, we present new spatially resolved astrometry and photometry from the Gemini Planet Imager of the inner binary of the young multiple star system V343 Normae, which is a member of the β Pictoris (β Pic) moving group. V343 Normae comprises a K0 and mid-M star in a ~4.5 year orbit (AaAb) and a wide 10'' M5 companion (B). By combining these data with archival astrometry and radial velocities we fit the orbit and measure individual masses for both components of ${M}_{\\mathrm{Aa}}=1.10\\pm 0.10\\,{M}_{\\odot }$ and ${M}_{\\mathrm{Ab}}=0.290\\pm 0.018\\,{M}_{\\odot }$. Comparing to theoretical isochrones, we find good agreement for the measured masses and JHK band magnitudes of the two components consistent with the age of the β Pic moving group. We derive a model-dependent age for the β Pic moving group of 26 ± 3 Myr by combining our results for V343 Normae with literature measurements for GJ 3305, which is another group member with resolved binary components and dynamical masses.

  6. Fomalhaut's Disk And Planet: Constraining The Mass And Orbit Of Fomalhaut-b Using Disk Morphology"

    NASA Astrophysics Data System (ADS)

    Chiang, Eugene; Kite, E.; Kalas, P.; Graham, J. R.; Clampin, M.

    2009-01-01

    We present a numerical model of how Fomalhaut b, the recently imaged exoplanet candidate, shapes Fomalhaut's debris disk. Our model indicates that Fomalhaut b must have a mass less than 3 Jupiter masses. Previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our new constraints on the mass and the orbit of Fomalhaut b are more reliable. They are based on a global model of the disk that is not restricted to the chaotic zone boundary. We screen disk parent bodies, which define Fomalhaut's birth ring, for dynamical stability over the system age. Parent bodies are modelled separately from their dust grain progeny, whose orbits are strongly affected by radiation pressure and whose lifetimes are limited to about 0.1 Myr by destructive grain-grain collisions. Parent bodies are evacuated from mean-motion resonances with Fomalhaut b; these empty resonances are akin to the Kirkwood gaps opened by Jupiter. The belt contains at least 3 Earth masses of solids that are grinding down to dust, their velocity dispersions stirred so strongly by Fomalhaut b that collisions are destructive.

  7. Conditions for water ice lines and Mars-mass exomoons around accreting super-Jovian planets at 1-20 AU from Sun-like stars

    NASA Astrophysics Data System (ADS)

    Heller, R.; Pudritz, R.

    2015-06-01

    Context. The first detection of a moon around an extrasolar planet (an "exomoon") might be feasible with NASA's Kepler or ESA's upcoming PLATO space telescopes or with the future ground-based European Extremely Large Telescope. To guide observers and to use observational resources most efficiently, we need to know where the largest, most easily detected moons can form. Aims: We explore the possibility of large exomoons by following the movement of water (H2O) ice lines in the accretion disks around young super-Jovian planets. We want to know how the different heating sources in those disks affect the location of the H2O ice lines as a function of stellar and planetary distance. Methods: We simulate 2D rotationally symmetric accretion disks in hydrostatic equilibrium around super-Jovian exoplanets. The energy terms in our semi-analytical framework - (1) viscous heating; (2) planetary illumination; (3) accretional heating of the disk; and (4) stellar illumination - are fed by precomputed planet evolution models. We consider accreting planets with final masses between 1 and 12 Jupiter masses at distances between 1 and 20 AU to a solar type star. Results: Accretion disks around Jupiter-mass planets closer than about 4.5 AU to Sun-like stars do not feature H2O ice lines, whereas the most massive super-Jovians can form icy satellites as close as 3 AU to Sun-like stars. We derive an empirical formula for the total moon mass as a function of planetary mass and stellar distance and predict that super-Jovian planets forming beyond about 5 AU can host Mars-mass moons. Planetary illumination is the major heat source in the final stages of accretion around Jupiter-mass planets, whereas disks around the most massive super-Jovians are similarly heated by planetary illumination and viscous heating. This indicates a transition towards circumstellar accretion disks, where viscous heating dominates in the stellar vicinity. We also study a broad range of circumplanetary disk

  8. 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.

  9. BAGEMASS: Bayesian age and mass estimates for transiting planet host stars

    NASA Astrophysics Data System (ADS)

    Maxted, P. F. L.; Serenelli, A. M.; Southworth, J.

    2017-08-01

    BAGEMASS calculates the posterior probability distribution for the mass and age of a star from its observed mean density and other observable quantities using a grid of stellar models that densely samples the relevant parameter space. It is written in Fortran and requires FITSIO (ascl:1010.001).

  10. Integral Field Spectroscopy of the Low-mass Companion HD 984 B with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Johnson-Groh, Mara; Marois, Christian; De Rosa, Robert J.; Nielsen, Eric L.; Rameau, Julien; Blunt, Sarah; Vargas, Jeffrey; Ammons, S. Mark; Bailey, Vanessa P.; Barman, Travis S.; Bulger, Joanna; Chilcote, Jeffrey K.; Cotten, Tara; Doyon, René; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Kate B.; Goodsell, Stephen; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn M.; Larkin, James E.; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Oppenheimer, Rebecca; Palmer, David W.; Patience, Jenny; Perrin, Marshall; Poyneer, Lisa A.; Pueyo, Laurent; Rajan, Abhijith; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J. Kent; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2017-04-01

    We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager (GPI) as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J (1.12–1.3 μm) and H (1.50–1.80 μm) bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au (70-year) orbit with a 68% confidence interval between 14 and 28 au, an eccentricity of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119° with a 68% confidence interval between 114° and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ± 1.5 spectral type with a corresponding temperature of {2730}-180+120 K. Photometry of the companion yields a luminosity of {log}({L}{bol}/{L}ȯ )=-2.88+/- 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ± 1 to 95 ± 4 M Jup. These results are consistent with previous measurements of the object.

  11. Integral field spectroscopy of the low-mass companion HD 984 B with the Gemini Planet Imager

    DOE PAGES

    Johnson-Groh, Mara; Marois, Christian; De Rosa, Robert J.; ...

    2017-03-31

    We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager (GPI) as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J (1.12–1.3 μm) and H (1.50–1.80 μm) bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au (70-year) orbit with a 68% confidence interval between 14 and 28 au, an eccentricity of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119° with a 68% confidence interval between 114° and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ± 1.5 spectral type with a corresponding temperature ofmore » $${2730}_{-180}^{+120}$$ K. Photometry of the companion yields a luminosity of $$\\mathrm{log}({L}_{\\mathrm{bol}}$$/$${L}_{\\odot })=-2.88\\pm 0.07$$ dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ± 1 to 95 ± 4 M Jup. Lastly, these results are consistent with previous measurements of the object.« less

  12. The Snow Line in Viscous Disks around Low-mass Stars: Implications for Water Delivery to Terrestrial Planets in the Habitable Zone

    NASA Astrophysics Data System (ADS)

    Mulders, Gijs D.; Ciesla, Fred J.; Min, Michiel; Pascucci, Ilaria

    2015-07-01

    The water-ice or snow line is one of the key properties of protoplanetary disks that determines the water content of terrestrial planets in the habitable zone. Its location is determined by the properties of the star, the mass accretion rate through the disk, and the size distribution of dust suspended in the disk. We calculate the snow-line location from recent observations of mass accretion rates and as a function of stellar mass. By taking the observed dispersion in mass accretion rates as a measure of the dispersion in initial disk mass, we find that stars of a given mass will exhibit a range of snow-line locations. At a given age and stellar mass, the observed dispersion in mass accretion rates of 0.4 dex naturally leads to a dispersion in snow-line locations of ˜0.2 dex. For ISM-like dust sizes, the 1σ snow-line location among solar-mass stars of the same age ranges from ˜2 to ˜5 AU. For more realistic dust opacities that include larger grains, the snow line is located up to two times closer to the star. We use these locations and the outcome of N-body simulations to predict the amount of water delivered to terrestrial planets that formed in situ in the habitable zone. We find that the dispersion in snow-line locations leads to a large range in water content. For ISM-like dust sizes, a significant fraction of habitable-zone terrestrial planets around Sun-like stars remain dry, and no water is delivered to the habitable zones of low-mass M stars (\\lt 0.5 {M}⊙ ) as in previous works. The closer-in snow line in disks with larger grains enables water delivery to the habitable zone for a significant fraction of M stars and all FGK stars. Considering their larger numbers and higher planet occurrence, M stars may host most of the water-rich terrestrial planets in the galaxy if these planets are able to hold on to their water in their subsequent evolution.

  13. 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.

  14. SPITZER AS A MICROLENS PARALLAX SATELLITE: MASS MEASUREMENT FOR THE OGLE-2014-BLG-0124L PLANET AND ITS HOST STAR

    SciTech Connect

    Udalski, A.; Skowron, J.; Kozłowski, S.; Poleski, R.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Mróz, P.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Yee, J. C.; Gould, A.; Zhu, W.; Pogge, R. W.; Carey, S.; Han, C.; Calchi Novati, S.

    2015-02-01

    We combine Spitzer and ground-based observations to measure the microlens parallax vector π{sub E}, and thus the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. The planet and star have masses of m ∼ 0.5 M {sub jup} and M ∼ 0.7 M {sub ☉} and are separated by a ∼ 3.1 AU in projection. The main source of uncertainty in all of these numbers (approximately 30%, 30%, and 20%) is the relatively poor measurement of the Einstein radius θ{sub E}, rather than uncertainty in π{sub E}, which is measured with 2.5% precision. This compares to 22% based on OGLE data alone, implying that the Spitzer data provide not only a substantial improvement in the precision of the π{sub E} measurement, but also the first independent test of a ground-based π{sub E} measurement.

  15. THE RADIAL VELOCITY DETECTION OF EARTH-MASS PLANETS IN THE PRESENCE OF ACTIVITY NOISE: THE CASE OF {alpha} CENTAURI Bb

    SciTech Connect

    Hatzes, Artie P.

    2013-06-20

    We present an analysis of the publicly available HARPS radial velocity (RV) measurements for {alpha} Cen B, a star hosting an Earth-mass planet candidate in a 3.24 day orbit. The goal is to devise robust ways of extracting low-amplitude RV signals of low-mass planets in the presence of activity noise. Two approaches were used to remove the stellar activity signal which dominates the RV variations: (1) Fourier component analysis (pre-whitening), and (2) local trend filtering (LTF) of the activity using short time windows of the data. The Fourier procedure results in a signal at P = 3.236 days and K = 0.42 m s{sup -1}, which is consistent with the presence of an Earth-mass planet, but the false alarm probability for this signal is rather high at a few percent. The LTF results in no significant detection of the planet signal, although it is possible to detect a marginal planet signal with this method using a different choice of time windows and fitting functions. However, even in this case the significance of the 3.24 day signal depends on the details of how a time window containing only 10% of the data is filtered. Both methods should have detected the presence of {alpha} Cen Bb at a higher significance than is actually seen. We also investigated the influence of random noise with a standard deviation comparable to the HARPS data and sampled in the same way. The distribution of the noise peaks in the period range 2.8-3.3 days has a maximum of Almost-Equal-To 3.2 days and amplitudes approximately one-half of the K-amplitude for the planet. The presence of the activity signal may boost the velocity amplitude of these signals to values comparable to the planet. It may be premature to attribute the 3.24 day RV variations to an Earth-mass planet. A better understanding of the noise characteristics in the RV data as well as more measurements with better sampling will be needed to confirm this exoplanet.

  16. Planet Demographics from Transits

    NASA Astrophysics Data System (ADS)

    Howard, Andrew

    2015-08-01

    From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.

  17. AB INITIO EQUATION OF STATE FOR HYDROGEN-HELIUM MIXTURES WITH RECALIBRATION OF THE GIANT-PLANET MASS-RADIUS RELATION

    SciTech Connect

    Militzer, B.; Hubbard, W. B.

    2013-09-10

    Using density functional molecular dynamics simulations, we determine the equation of state (EOS) for hydrogen-helium mixtures spanning density-temperature conditions typical of giant-planet interiors, {approx}0.2-9 g cm{sup -3} and 1000-80,000 K for a typical helium mass fraction of 0.245. In addition to computing internal energy and pressure, we determine the entropy using an ab initio thermodynamic integration technique. A comprehensive EOS table with 391 density-temperature points is constructed and the results are presented in the form of a two-dimensional free energy fit for interpolation. Deviations between our ab initio EOS and the semi-analytical EOS model by Saumon and Chabrier are analyzed in detail, and we use the results for initial revision of the inferred thermal state of giant planets with known values for mass and radius. Changes are most pronounced for planets in the Jupiter mass range and below. We present a revision to the mass-radius relationship that makes the hottest exoplanets increase in radius by {approx}0.2 Jupiter radii at fixed entropy and for masses greater than {approx}0.5 Jupiter mass. This change is large enough to have possible implications for some discrepant ''inflated giant exoplanets''.

  18. The mass of planet GJ 676A b from ground-based astrometry. A planetary system with two mature gas giants suitable for direct imaging

    NASA Astrophysics Data System (ADS)

    Sahlmann, J.; Lazorenko, P. F.; Ségransan, D.; Astudillo-Defru, N.; Bonfils, X.; Delfosse, X.; Forveille, T.; Hagelberg, J.; Lo Curto, G.; Pepe, F.; Queloz, D.; Udry, S.; Zimmerman, N. T.

    2016-11-01

    The star GJ 676A is an M0 dwarf hosting both gas-giant and super-Earth-type planets that were discovered with radial-velocity measurements. Using FORS2/VLT, we obtained position measurements of the star in the plane of the sky that tightly constrain its astrometric reflex motion caused by the super-Jupiter planet "b" in a 1052-day orbit. This allows us to determine the mass of this planet to be , which is 40% higher than the minimum mass inferred from the radial-velocity orbit. Using new HARPS radial-velocity measurements, we improve upon the orbital parameters of the inner low-mass planets "d" and "e" and we determine the orbital period of the outer giant planet "c" to be Pc = 7340 days under the assumption of a circular orbit. The preliminary minimum mass of planet "c" is Mcsini = 6.8 MJ with an upper limit of 39 MJ that we set using NACO/VLT high-contrast imaging. We also determine precise parallaxes and relative proper motions for both GJ 676A and its wide M3 companion GJ 676B. Although the system is probably quite mature, the masses and projected separations ( 0.̋1-0.̋4) of planets "b" and "c" make them promising targets for direct imaging with future instruments in space and on extremely large telescopes. In particular, we estimate that GJ 676A b and GJ 676A c are promising targets for directly detecting their reflected light with the WFIRST space mission. Our study demonstrates the synergy of radial-velocity and astrometric surveys that is necessary to identify the best targets for such a mission. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 385.C-0416 (A,B), 086.C-0515(A), 089.C-0115(D,E), 072.C-0488(E), 180.C-0886(A), 183.C-0437(A), 085.C-0019(A), 091.C-0034(A), 095.C-0551(A), 096.C-0460(A).Full Table A.2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A77

  19. The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet

    SciTech Connect

    Dumusque, Xavier; Buchhave, Lars A.; Latham, David W.; Charbonneau, David; Dressing, Courtney D.; Gettel, Sara; Lopez-Morales, Mercedes; Bonomo, Aldo S.; Haywood, Raphaëlle D.; Cameron, Andrew Collier; Horne, Keith; Malavolta, Luca; Ségransan, Damien; Pepe, Francesco; Udry, Stéphane; Molinari, Emilio; Cosentino, Rosario; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Figueira, Pedro; and others

    2014-07-10

    Kepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M{sub ⊕} for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M{sub ⊕} and an updated radius of 1.47{sub −0.02}{sup +0.03} R{sub ⊕}, Kepler-10b has a density of 5.8 ± 0.8 g cm{sup –3}, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M{sub ⊕} and radius of 2.35{sub −0.04}{sup +0.09} R{sub ⊕}, Kepler-10c has a density of 7.1 ± 1.0 g cm{sup –3}. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.

  20. The Kepler-10 Planetary System Revisited by HARPS-N: A Hot Rocky World and a Solid Neptune-Mass Planet

    NASA Astrophysics Data System (ADS)

    Dumusque, Xavier; Bonomo, Aldo S.; Haywood, Raphaëlle D.; Malavolta, Luca; Ségransan, Damien; Buchhave, Lars A.; Collier Cameron, Andrew; Latham, David W.; Molinari, Emilio; Pepe, Francesco; Udry, Stéphane; Charbonneau, David; Cosentino, Rosario; Dressing, Courtney D.; Figueira, Pedro; Fiorenzano, Aldo F. M.; Gettel, Sara; Harutyunyan, Avet; Horne, Keith; Lopez-Morales, Mercedes; Lovis, Christophe; Mayor, Michel; Micela, Giusi; Motalebi, Fatemeh; Nascimbeni, Valerio; Phillips, David F.; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Sozzetti, Alessandro; Szentgyorgyi, Andrew; Watson, Chris

    2014-07-01

    Kepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M ⊕ for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M ⊕ and an updated radius of 1.47+0.03-0.02 R ⊕, Kepler-10b has a density of 5.8 ± 0.8 g cm-3, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M ⊕ and radius of 2.35+0.09-0.04 R ⊕, Kepler-10c has a density of 7.1 ± 1.0 g cm-3. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundacin Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  1. A Scientometric Prediction of the Discovery of the First Potentially Habitable Planet with a Mass Similar to Earth

    PubMed Central

    Arbesman, Samuel; Laughlin, Gregory

    2010-01-01

    Background The search for a habitable extrasolar planet has long interested scientists, but only recently have the tools become available to search for such planets. In the past decades, the number of known extrasolar planets has ballooned into the hundreds, and with it, the expectation that the discovery of the first Earth-like extrasolar planet is not far off. Methodology/Principal Findings Here, we develop a novel metric of habitability for discovered planets and use this to arrive at a prediction for when the first habitable planet will be discovered. Using a bootstrap analysis of currently discovered exoplanets, we predict the discovery of the first Earth-like planet to be announced in the first half of 2011, with the likeliest date being early May 2011. Conclusions/Significance Our predictions, using only the properties of previously discovered exoplanets, accord well with external estimates for the discovery of the first potentially habitable extrasolar planet and highlight the the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields. PMID:20957226

  2. A scientometric prediction of the discovery of the first potentially habitable planet with a mass similar to Earth.

    PubMed

    Arbesman, Samuel; Laughlin, Gregory

    2010-10-04

    The search for a habitable extrasolar planet has long interested scientists, but only recently have the tools become available to search for such planets. In the past decades, the number of known extrasolar planets has ballooned into the hundreds, and with it, the expectation that the discovery of the first Earth-like extrasolar planet is not far off. Here, we develop a novel metric of habitability for discovered planets and use this to arrive at a prediction for when the first habitable planet will be discovered. Using a bootstrap analysis of currently discovered exoplanets, we predict the discovery of the first Earth-like planet to be announced in the first half of 2011, with the likeliest date being early May 2011. Our predictions, using only the properties of previously discovered exoplanets, accord well with external estimates for the discovery of the first potentially habitable extrasolar planet and highlight the the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields.

  3. Exploring Disks Around Planets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-07-01

    Giant planets are thought to form in circumstellar disks surrounding young stars, but material may also accrete into a smaller disk around the planet. Weve never detected one of these circumplanetary disks before but thanks to new simulations, we now have a better idea of what to look for.Image from previous work simulating a Jupiter-mass planet forming inside a circumstellar disk. The planet has its own circumplanetary disk of accreted material. [Frdric Masset]Elusive DisksIn the formation of giant planets, we think the final phase consists of accretion onto the planet from a disk that surrounds it. This circumplanetary disk is important to understand, since it both regulates the late gas accretion and forms the birthplace of future satellites of the planet.Weve yet to detect a circumplanetary disk thus far, because the resolution needed to spot one has been out of reach. Now, however, were entering an era where the disk and its kinematics may be observable with high-powered telescopes (like the Atacama Large Millimeter Array).To prepare for such observations, we need models that predict the basic characteristics of these disks like the mass, temperature, and kinematic properties. Now a researcher at the ETH Zrich Institute for Astronomy in Switzerland, Judit Szulgyi, has worked toward this goal.Simulating CoolingSzulgyi performs a series of 3D global radiative hydrodynamic simulations of 1, 3, 5, and 10 Jupiter-mass (MJ) giant planets and their surrounding circumplanetary disks, embedded within the larger circumstellar disk around the central star.Density (left column), temperature (center), and normalized angular momentum (right) for a 1 MJ planet over temperatures cooling from 10,000 K (top) to 1,000 K (bottom). At high temperatures, a spherical circumplanetary envelope surrounds the planet, but as the planet cools, the envelope transitions around 64,000 K to a flattened disk. [Szulgyi 2017]This work explores the effects of different planet temperatures and

  4. 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.

  5. Short-duration Lensing Events. I. Wide-orbit Planets? Free-floating Low-mass Objects? Or High-velocity Stars?

    NASA Astrophysics Data System (ADS)

    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.

  6. Planets, planets everywhere

    NASA Astrophysics Data System (ADS)

    1999-09-01

    The authors, an international team led by Harm Habing, from Leiden University (The Netherlands), wanted to know if stars belonging to a particular class were more likely than others to form planets. In our own Solar System planets formed out of a disc of small particles of dust, so every star surrounded by such a disc is a potential planet-forming star. The astronomers therefore chose a sample of 84 nearby stars, all of them very common and in the most stable phase of their lives - the 'main sequence' - but of different ages. Which ones would have discs? Discs are difficult to see because they emit very faintly; only a few had been positively detected so far. Using ESA's highly sensitive infrared space observatory, ISO, the international team found that 15 stars in their sample did have a disc. Then they analysed the ages of the stars: it turned out that most of those younger than 400 million years had discs, while the great majority of the older ones did not. "We show for the first time that the presence of a disc around a main sequence star depends strongly on the star's age. Why do those above a precise age not have discs? We searched for clues in our own Solar System, and realised that it was just when the Sun was that age (about 400 million years) that planets were forming", Habing says. In our Solar System, several facts demonstrate that very soon after the formation of the planets the disc orbiting the Sun disappeared. Some evidence comes, for instance, from Moon craters. These 'scars' on the lunar surface were made while the planets were completing their formation phase and the Sun was losing its own disc of debris, during the 'clean-up phase' of the Solar System. The newly-born planets scattered the remaining planetesimals, which were ejected from the system, fell into the Sun or collided with other large bodies - such as the Moon. The age determinations of lunar rocks brought back by the Apollo missions prove that all this happened when the Sun was 300 to

  7. 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.

  8. 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.

  9. Wave of a Planet

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This plot tells astronomers that a fifth planet is in orbit around the star 55 Cancri, making the star the record-holder for hosting the most known exoplanets.

    As planets circle around their stars, they cause the stars to wobble back and forth in a regular pattern. By looking for this motion in a star, scientists can find planets that can't be seen with telescopes.

    The wobble caused by the fifth planet discovered around 55 Cancri is represented here by the sinuous line in blue. The actual data points are yellow and error bars are the lines above and below the yellow dots. The cycle of the wobble indicates that the planet circles around its star about every 260 days. The amplitude of the wobble indicates that the planet is a giant at least 45 times the mass of Earth.

    The wobbles caused by the other four planets has been removed from this plot, to reveal that caused by the fifth. The departure from a perfect sine wave suggests the planet's orbit is not perfectly circular.

    Because 55 Cancri has multiple planets, the star had to be observed for a long time before astronomers could find and confirm its fifth planet. These data were collected over a period of 18 years using both the Lick Observatory near San Jose, Calif., and the W.M. Keck Observatory in Hawaii.

  10. HAT-P-12b: A LOW-DENSITY SUB-SATURN MASS PLANET TRANSITING A METAL-POOR K DWARF

    SciTech Connect

    Hartman, J. D.; Bakos, G. A.; Torres, G.; Noyes, R. W.; Pal, A.; Latham, D. W.; Sipocz, B.; Esquerdo, G. A.; Sasselov, D. D.; Kovacs, Gabor; Stefanik, R. P.; Fernandez, J. M.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Butler, R. P.; Lazar, J.; Papp, I.

    2009-11-20

    We report on the discovery of HAT-P-12b, a transiting extrasolar planet orbiting the moderately bright V approx 12.8 K4 dwarf GSC 03033 - 00706, with a period P = 3.2130598 +- 0.0000021 d, transit epoch T{sub c} = 2454419.19556 +- 0.00020 (BJD), and transit duration 0.0974 +- 0.0006 d. The host star has a mass of 0.73 +- 0.02 M{sub sun}, radius of 0.70{sup +0.02}{sub -0.01} R{sub sun}, effective temperature 4650 +- 60 K, and metallicity [Fe/H] = -0.29 +- 0.05. We find a slight correlation between the observed spectral line bisector spans and the radial velocity, so we consider, and rule out, various blend configurations including a blend with a background eclipsing binary, and hierarchical triple systems where the eclipsing body is a star or a planet. We conclude that a model consisting of a single star with a transiting planet best fits the observations, and show that a likely explanation for the apparent correlation is contamination from scattered moonlight. Based on this model, the planetary companion has a mass of 0.211 +- 0.012 M{sub J} and radius of 0.959{sup +0.029}{sub -0.021} R{sub J} yielding a mean density of 0.295 +- 0.025 g cm{sup -3}. Comparing these observations with recent theoretical models, we find that HAT-P-12b is consistent with a approx1-4.5 Gyr, mildly irradiated, H/He-dominated planet with a core mass M{sub C} approx< 10 M {sub +}. HAT-P-12b is thus the least massive H/He-dominated gas giant planet found to date. This record was previously held by Saturn.

  11. 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.

  12. 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.

  13. 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.

  14. A Combined Subaru/VLT/MMT 1-5 Micrometer Study of Planets Orbiting HR 8799: Implications For Atmospheric Properties, Masses and Formation

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Burrows, Adam; Itoh, Yoichi; Matsumura, Soko; Fukagawa, Misato; Apai, Daniel; Madhusudhan, Nikku; Hinz, Philip M.; Rodigas, T. J.; Kasper, Markus; hide

    2011-01-01

    We present new 1-1.25 micron (z and J band) Subaru/IRCS and 2 micron (K band) VLT/NaCo data for HR 8799 and a rereduction of the 3-5 micron MMT/Clio data first presented by Hinz et al. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of approximately 15 AU--"HR 8799e ." We also report new, albeit weak detections of HR 8799b at 1.03 micron and 3.3 micron. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/ magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for unphysically small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for resealing the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T(sub eff) = 900 K. while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T(sub eff) = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M(sub j), 7-10 M(sub j), 7-10 M(sub j), and 7-10 M(sub j). "Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.

  15. A Combined Subaru/VLT/MMT 1-5 Micrometer Study of Planets Orbiting HR 8799: Implications For Atmospheric Properties, Masses and Formation

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Burrows, Adam; Itoh, Yoichi; Matsumura, Soko; Fukagawa, Misato; Apai, Daniel; Madhusudhan, Nikku; Hinz, Philip M.; Rodigas, T. J.; Kasper, Markus; Pyo, T.-S.; Ogino, Satoshi

    2011-01-01

    We present new 1-1.25 micron (z and J band) Subaru/IRCS and 2 micron (K band) VLT/NaCo data for HR 8799 and a rereduction of the 3-5 micron MMT/Clio data first presented by Hinz et al. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of approximately 15 AU--"HR 8799e ." We also report new, albeit weak detections of HR 8799b at 1.03 micron and 3.3 micron. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/ magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for unphysically small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for resealing the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T(sub eff) = 900 K. while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T(sub eff) = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M(sub j), 7-10 M(sub j), 7-10 M(sub j), and 7-10 M(sub j). "Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.

  16. HAT-P-18b AND HAT-P-19b: TWO LOW-DENSITY SATURN-MASS PLANETS TRANSITING METAL-RICH K STARS

    SciTech Connect

    Hartman, J. D.; Bakos, G. A.; Torres, G.; Noyes, R. W.; Latham, D. W.; Buchhave, L. A.; Fueresz, G.; Perumpilly, G.; Beky, B.; Stefanik, R. P.; Sasselov, D. D.; Esquerdo, G. A.; Everett, M.; Csubry, Z.; Sato, B.; Kovacs, G.; Fischer, D. A.; Howard, A. W.; Marcy, G. W.; Johnson, J. A.

    2011-01-01

    We report the discovery of two new transiting extrasolar planets. HAT-P-18b orbits the V = 12.759 K2 dwarf star GSC 2594-00646, with a period P = 5.508023 {+-} 0.000006 days, transit epoch T{sub c} = 2454715.02174 {+-} 0.00020 (BJD), and transit duration 0.1131 {+-} 0.0009 days. The host star has a mass of 0.77 {+-} 0.03 M{sub sun}, radius of 0.75 {+-} 0.04 R{sub sun}, effective temperature 4803 {+-} 80 K, and metallicity [Fe/H] = +0.10 {+-} 0.08. The planetary companion has a mass of 0.197 {+-} 0.013 M{sub J} and radius of 0.995 {+-} 0.052 R{sub J}, yielding a mean density of 0.25 {+-} 0.04 g cm{sup -3}. HAT-P-19b orbits the V = 12.901 K1 dwarf star GSC 2283-00589, with a period P = 4.008778 {+-} 0.000006 days, transit epoch T{sub c} = 2455091.53417 {+-} 0.00034 (BJD), and transit duration 0.1182 {+-} 0.0014 days. The host star has a mass of 0.84 {+-} 0.04 M{sub sun}, radius of 0.82 {+-} 0.05 R{sub sun}, effective temperature 4990 {+-} 130 K, and metallicity [Fe/H] = +0.23 {+-} 0.08. The planetary companion has a mass of 0.292 {+-} 0.018 M{sub J} and radius of 1.132 {+-} 0.072 R{sub J}, yielding a mean density of 0.25 {+-} 0.04 g cm{sup -3}. The radial velocity residuals for HAT-P-19 exhibit a linear trend in time, which indicates the presence of a third body in the system. Comparing these observations with theoretical models, we find that HAT-P-18b and HAT-P-19b are each consistent with a hydrogen-helium-dominated gas giant planet with negligible core mass. HAT-P-18b and HAT-P-19b join HAT-P-12b and WASP-21b in an emerging group of low-density Saturn-mass planets, with negligible inferred core masses. However, unlike HAT-P-12b and WASP-21b, both HAT-P-18b and HAT-P-19b orbit stars with super-solar metallicity. This calls into question the heretofore suggestive correlation between the inferred core mass and host star metallicity for Saturn-mass planets.

  17. 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.

  18. Atmospheric expansion in runaway greenhouse atmospheres: the inner edge of the habitable zone depends on planet mass

    NASA Astrophysics Data System (ADS)

    Goldblatt, C.; Zahnle, K. J.

    2014-12-01

    As a wet planet becomes hot, evaporation of the ocean provides a thick steam atmosphere. As the atmosphere thickens, the level at which optical depth is unity (whence radiative emission and absorption dominantly occur) rises into the atmosphere, first for thermal wavelengths and later for solar wavelengths. Consequently, two radiation limits emerge. First, an asymptotic limit on the thermal radiation, as the level at which thermal emission occurs tends towards a fixed temperature, decoupled from surface temperature. Next, a limit the albedo of the planet, as all incoming sunlight is either reflected or absorbed in the atmosphere and almost none reaches the surface. A runaway greenhouse occurs when the product of co-albedo and area-averaged incoming sunlight exceeds the thermal radiation limit. Earth today is perilously close to this [1].Returning to the first sentence, we generate a thick atmosphere: the height of optical depth of unity becomes a non-trivial fraction of the planetary radius. Hence the area of the absorbing and emitting surfaces increase. Thermal emission wins slightly, as this occurs higher, increasing thermal emission in all cases. The underlying tendency is for a larger thermal limit for heavier planets due to pressure effects, making these appear more resistant to a runaway. However, atmospheric expansion affects light planets more, making these seem much more resilient. The least resilient planet would be between Mars-size and Venus-size (Figure 1). It would be foolish to regard small planets as habitable. As the atmospheres become large, so does the problem of atmospheric escape. Theoretical considerations show hydrodynamic escape to happen disastrously for a Europa-size planet. The observation is that Mars is too feeble to hold on to any hefty atmosphere, even far from the Sun as it is, is probably relevant too. The take home points for habitable zone nerds are: (1) planet size matters (2) for small planets, atmospheric escape from a "moist

  19. Planets around Low-mass Stars (PALMS). VI. Discovery of a Remarkably Red Planetary-mass Companion to the AB Dor Moving Group Candidate 2MASS J22362452+4751425*

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Mawet, Dimitri; Ngo, Henry; Malo, Lison; Mace, Gregory N.; McLane, Jacob N.; Lu, Jessica R.; Tristan, Isaiah I.; Hinkley, Sasha; Hillenbrand, Lynne A.; Shkolnik, Evgenya L.; Benneke, Björn; Best, William M. J.

    2017-01-01

    We report the discovery of an extremely red planetary-mass companion to 2MASS J22362452+4751425, a ≈0.6 M⊙ late-K dwarf likely belonging to the ˜120 Myr AB Doradus moving group. 2M2236+4751 b was identified in multi-epoch NIRC2 adaptive optics imaging at Keck Observatory at a separation of 3\\buildrel{\\prime\\prime}\\over{.} 7, or 230 ± 20 AU in projection at the kinematic distance of 63 ± 5 pc to its host star. Assuming membership in the AB Dor group, as suggested from its kinematics, the inferred mass of 2M2236+4751 b is 11-14 MJup. Follow-up Keck/OSIRIS K-band spectroscopy of the companion reveals strong CO absorption similar to other faint red L dwarfs and lacks signs of methane absorption, despite having an effective temperature of ≈900-1200 K. With a (J-K)MKO color of 2.69 ± 0.12 mag, the near-infrared slope of 2M2236+4751 b is redder than all of the HR 8799 planets and instead resembles the ≈23 Myr isolated planetary-mass object PSO J318.5-22, implying that similarly thick photospheric clouds can persist in the atmospheres of giant planets at ages beyond 100 Myr. In near-infrared color-magnitude diagrams, 2M2236+4751 b is located at the tip of the red L dwarf sequence and appears to define the “elbow” of the AB Dor substellar isochrone separating low-gravity L dwarfs from the cooler young T dwarf track. 2M2236+4751 b is the reddest substellar companion to a star and will be a valuable benchmark to study the shared atmospheric properties of young low-mass brown dwarfs and extrasolar giant planets. 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.

  20. How Do Earth-Sized, Short-Period Planets Form?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-08-01

    day)23 hot Jupiters (larger than 4 times Earths radius and orbital period shorter than 10 days)243 small hot planets (smaller than 4 times Earths radius and orbital period between 1 and 10 days)They then compare the metallicity distributions of these three groups.Back to the Drawing BoardMetallicity distributions of the three statistical samples. The hot-Jupiter hosts (orange) have different distribution than the others; it is weighted more toward higher metallicities. [Winn et al. 2017]Winn and collaborators find that hosts of ultra-short-period planets do not have the same metallicity distribution as hot-Jupiter hosts; the metallicities of hot-Jupiter hosts are significantly higher. The metallicity distributions for hosts of ultra-short-period planets and hosts of small hot planets were statistically indistinguishable, however.These results strongly suggest that the majority of ultra-short-period planets are not the cores of former hot Jupiters. Alternative options include the possibility that they are the cores of smaller planets, such as sub-Neptunes, or that they are the short-period extension of the distribution of close-in, small rocky planets that formed by core accretion.This narrowing of the options for the formation of ultra-short-period planets is certainly intriguing. We can hope to further explore possibilities in the future after the Transiting Exoplanet Survey Satellites (TESS) comes online next year; TESS is expected to discover many more ultra-short-period planets that are too faint for Kepler to detect.CitationJoshua N. Winn et al 2017 AJ 154 60. doi:10.3847/1538-3881/aa7b7c

  1. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of 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 as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. 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, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  2. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of 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 as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. 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, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  3. Iceball Planet Artist's Concept

    NASA Image and Video Library

    2017-04-26

    This artist's concept shows OGLE-2016-BLG-1195Lb, a planet discovered through a technique called microlensing. The planet was reported in a 2017 study in the Astrophysical Journal Letters. Study authors used the Korea Microlensing Telescope Network (KMTNet), operated by the Korea Astronomy and Space Science Institute, and NASA's Spitzer Space Telescope, to track the microlensing event and find the planet. Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our sun, the similarities may end there. This planet is nearly 13,000 light-years away and orbits a star so small, scientists aren't sure if it's a star at all. https://photojournal.jpl.nasa.gov/catalog/PIA21430

  4. The NASA-UC-UH ETA-Earth Program. IV. A Low-mass Planet Orbiting an M Dwarf 3.6 PC from Earth

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 ⊕, 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 & 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 ⊙ based on interferometry from CHARA. 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. Keck time was granted for this project by the University of Hawaii, the University of California, and NASA.

  5. 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.

  6. Complex patterns in the distribution of planets show planet migration and planet and star properties

    NASA Astrophysics Data System (ADS)

    Taylor, Stuart F.

    2015-08-01

    We present dramatic patterns in the distribution of exoplanet periods and eccentricities that vary as functions of iron abundance of the host star, planet mass, stellar properties, and presence of a stellar companion. These patterns include surprising peaks and gaps. They raise the question of whether planets themselves contribute to increasing stellar metallicity by causing other planets or material to “pollute” the star.We also show that the falloff in planets at the shortest periods can be used to determine the rate of planets migrating into the star as a function of the strength of tidal dissipation in the star. A small rate of planets migrating into the star can produce the observed population of the shortest period planets without having to invoke extremely weak tidal dissipation. Tidal dissipation strengths stronger than the tidal quality factor Q being equal to 107 are possible if there is a moderate flow of giant planets into the star. It is likely that within a decade it will be possible to measure the time shift of transits of the shortest period orbits due to orbital period decreases caused by tidal migration.The distribution of the shortest period planets indicates that the strength of tidal dissipation in stars is a function of stellar mass, making it worthwhile to monitor the shortest period systems for time shifts across a range of stellar masses. This time shift is inversely proportional to the lifetime of a planet.It is essential to know the rate of planets migrating into stars in order to understand whether inflated planets are only briefly inflated during a faster migration into the star, or if planets maintain anomalously large radii for longer periods of time.The paucity of Neptune-mass planets at the shortest periods could be due either to a lower rate of inward migration or to evaporation. Knowing how evaporation contributes to this paucity could help determine the fractions of planets that are rock, liquid water, or gas.

  7. Exotic Earths: forming habitable worlds with giant planet migration.

    PubMed

    Raymond, Sean N; Mandell, Avi M; Sigurdsson, Steinn

    2006-09-08

    Close-in giant planets (e.g., "hot Jupiters") are thought to form far from their host stars and migrate inward, through the terrestrial planet zone, via torques with a massive gaseous disk. Here we simulate terrestrial planet growth during and after giant planet migration. Several-Earth-mass planets also form interior to the migrating jovian planet, analogous to recently discovered "hot Earths." Very-water-rich, Earth-mass planets form from surviving material outside the giant planet's orbit, often in the habitable zone and with low orbital eccentricities. More than a third of the known systems of giant planets may harbor Earth-like planets.

  8. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that most single stars should have rocky planets in orbit about them; the frequency 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. Models for the formation of the giant planets found in recent radial velocity searches are discussed.

  9. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    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.

  10. Simulated JWST/NIRISS Spectroscopy of Anticipated TESS Planets and Selected Super-Earths Discovered from K2 and Ground-Based Surveys

    NASA Astrophysics Data System (ADS)

    Louie, Dana; Albert, Loic; Deming, Drake

    2017-01-01

    The 2018 launch of James Webb Space Telescope (JWST), coupled with the 2017 launch of the Transiting Exoplanet Survey Satellite (TESS), heralds a new era in Exoplanet Science, with TESS projected to detect over one thousand transiting sub-Neptune-sized planets (Ricker et al, 2014), and JWST offering unprecedented spectroscopic capabilities. Sullivan et al (2015) used Monte Carlo simulations to predict the properties of the planets that TESS is likely to detect, and published a catalog of 962 simulated TESS planets. Prior to TESS launch, the re-scoped Kepler K2 mission and ground-based surveys such as MEarth continue to seek nearby Earth-like exoplanets orbiting M-dwarf host stars. The exoplanet community will undoubtedly employ JWST for atmospheric characterization follow-up studies of promising exoplanets, but the targeted planets for these studies must be chosen wisely to maximize JWST science return. The goal of this project is to estimate the capabilities of JWST’s Near InfraRed Imager and Slitless Spectrograph (NIRISS)—operating with the GR700XD grism in Single Object Slitless Spectrography (SOSS) mode—during observations of exoplanets transiting their host stars. We compare results obtained for the simulated TESS planets, confirmed K2-discovered super-Earths, and exoplanets discovered using ground-based surveys. By determining the target planet characteristics that result in the most favorable JWST observing conditions, we can optimize the choice of target planets in future JWST follow-on atmospheric characterization studies.

  11. Kepler-11 is a Solar Twin: Revising the Masses and Radii of Benchmark Planets via Precise Stellar Characterization

    NASA Astrophysics Data System (ADS)

    Bedell, Megan; Bean, Jacob L.; Meléndez, Jorge; Mills, Sean M.; Fabrycky, Daniel C.; Freitas, Fabrício C.; Ramírez, Ivan; Asplund, Martin; Liu, Fan; Yong, David

    2017-04-01

    The six planets of the Kepler-11 system are the archetypal example of a population of surprisingly low-density transiting planets revealed by the Kepler mission. We have determined the fundamental parameters and chemical composition of the Kepler-11 host star to unprecedented precision using an extremely high-quality spectrum from Keck-HIRES (R ≃ 67,000, S/N per pixel ≃ 260 at 600 nm). Contrary to previously published results, our spectroscopic constraints indicate that Kepler-11 is a young main-sequence solar twin. The revised stellar parameters and new analysis raise the densities of the Kepler-11 planets by between 20% and 95% per planet, making them more typical of the emerging class of “puffy” close-in exoplanets. We obtain photospheric abundances of 22 elements and find that Kepler-11 has an abundance pattern similar to that of the Sun with a slightly higher overall metallicity. We additionally analyze the Kepler light curves using a photodynamical model and discuss the tension between spectroscopic and transit/TTV-based estimates of stellar density.

  12. The Search for Planet Nine

    NASA Astrophysics Data System (ADS)

    Brown, Michael E.; Batygin, Konstantin

    2016-10-01

    We use an extensive suite of numerical simulations to constrain the mass and orbit of Planet Nine, and we use these constraints to begin the search for this newly proposed planet in new and in archival data. Here, we compare our simulations to the observed population of aligned eccentric high semimajor axis Kuiper belt objects and determine which simulation parameters are statistically compatible with the observations. We find that only a narrow range of orbital elements can reproduce the observations. In particular, the combination of semimajor axis, eccentricity, and mass of Planet Nine strongly dictates the semimajor axis range of the orbital confinement of the distant eccentric Kuiper belt objects. Allowed orbits, which confine Kuiper belt objects with semimajor axis beyond 380 AU, have perihelia roughly between 150 and 350 AU, semimajor axes between 380 and 980 AU, and masses between 5 and 20 Earth masses. Orbitally confined objects also generally have orbital planes similar to that of the planet, suggesting that the planet is inclined approximately 30 degrees to the ecliptic. We compare the allowed orbital positions and estimated brightness of Planet Nine to previous and ongoing surveys which would be sensitive to the planet's detection and use these surveys to rule out approximately two-thirds of the planet's orbit. Planet Nine is likely near aphelion with an approximate brightness of 22planet.

  13. The planet Mercury (1971)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

  14. Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

    NASA Astrophysics Data System (ADS)

    Reffert, S.; Quirrenbach, A.

    2011-03-01

    Context. The recently completed re-reduction of the Hipparcos data by van Leeuwen (2007a, Astrophysics and Space Science Library, 350) makes it possible to search for the astrometric signatures of planets and brown dwarfs known from radial velocity surveys in the improved Hipparcos intermediate astrometric data. Aims: Our aim is to put more significant constraints on the orbital parameters which cannot be derived from radial velocities alone, i.e. the inclination and the longitude of the ascending node, than was possible before. The determination of the inclination in particular allows to calculate an unambiguous companion mass, rather than the lower mass limit which can be obtained from radial velocity measurements. Methods: We fitted the astrometric orbits of 310 substellar companions around 258 stars, which were all discovered via the radial velocity method, to the Hipparcos intermediate astrometric data provided by van Leeuwen. Results: Even though the astrometric signatures of the companions cannot be detected in most cases, the Hipparcos data still provide lower limits on the inclination for all but 67 of the investigated companions, which translates into upper limits on the masses of the unseen companions. For nine companions the derived upper mass limit lies in the planetary and for 75 companions in the brown dwarf mass regime, proving the substellar nature of those objects. Two of those objects have minimum masses also in the brown dwarf regime and are thus proven to be brown dwarfs. The confirmed planets are the ones around Pollux (β Gem b), ɛ Eri b, ɛ Ret b, μ Ara b, υ And c and d, 47 UMa b, HD 10647 b and HD 147513 b. The confirmed brown dwarfs are HD 137510 b and HD 168443 c. In 20 cases, the astrometric signature of the substellar companion was detected in the Hipparcos data, resulting in reasonable constraints on inclination and ascending node. Of these 20 companions, three are confirmed as planets or lightweight brown dwarfs (HD 87833 b, ι Dra

  15. Observations of Outer Solar System Satellites and Planets

    NASA Astrophysics Data System (ADS)

    Houck, James R.; van Cleve, Jeffrey

    2004-09-01

    We examine the principal satellites of outer Solar System planets, as well as Uranus, Neptune, and Pluto, using all SIRTF instruments. IRAC photometry will establish the hitherto unknown albedo of these cold objects at wavelengths between 3.5 and 8 microns, IRS will do reflectance spectrosopy at wavelengths between 5.3 and 15 um, and thermal emission spectroscopy between 10 and 40 um. Combined with MIPS photometry and SED measurements, these data willl provide compositional information, albedo, and thermal properties of these objects. All synchronous satellites are observed at leading and trailing hemispheres, while in addition the sub-Neptune hemisphere of Triton, and a series of follow-on measurements of this particularly interesting moon, are performed. The observations of Uranus and Neptune will be used to monitor atmospheric trends seen by HST and ISO, for trace composition data, and for precise straylight subtraction for observations of their innermost principal satellites. Observations of Titan will be examined for different spectral signatures of the hemisphere containing the "continent" seen in near-IR Hubble images compared to the trailing hemisphere, and interpreted in terms of surface composition and temperature.

  16. 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

  17. Extrasolar planets.

    PubMed

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

    2000-11-07

    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.

  18. The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by ground-based photometry

    NASA Astrophysics Data System (ADS)

    Nascimbeni, V.; Piotto, G.; Pagano, I.; Scandariato, G.; Sani, E.; Fumana, M.

    2013-11-01

    GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a nearby M1.5 dwarf. It is crucial for atmospheric studies because it is one of the most inflated low-mass planets known, bridging the boundary between "super-Earths" and Neptunian planets. We present two new ground-based light curves of GJ3470b gathered by the LBC camera at the Large Binocular Telescope. Simultaneous photometry in the ultraviolet (λc = 357.5 nm) and optical infrared (λc = 963.5 nm) allowed us to detect a significant change in the effective radius of GJ3470b as a function of wavelength. This can be interpreted as a signature of scattering processes occurring in the planetary atmosphere, which should be cloud-free and with a low mean molecular weight. The unprecedented accuracy of our measurements demonstrates that the photometric detection of Earth-sized planets around M dwarfs is achievable using 8-10 m size ground-based telescopes. We provide updated planetary parameters and a greatly improved orbital ephemeris for any forthcoming study of this planet. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota, and University of Virginia.Photometric data 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/559/A32

  19. 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.

  20. 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.

  1. Astrometric Planet Searches with SIM PlanetQuest

    NASA Technical Reports Server (NTRS)

    Beichman, Charles A.; Unwin, Stephen C.; Shao, Michael; Tanner, Angelle M.; Catanzarite, Joseph H.; March, Geoffrey W.

    2007-01-01

    SIM will search for planets with masses as small as the Earth's orbiting in the habitable zones' around more than 100 of the stars and could discover many dozen if Earth-like planets are common. With a planned 'Deep Survey' of 100-450 stars (depending on desired mass sensitivity) SIM will search for terrestrial planets around all of the candidate target stars for future direct detection missions such as Terrestrial Planet Finder and Darwin, SIM's 'Broad Survey' of 2010 stars will characterize single and multiple-planet systems around a wide variety of stellar types, including many now inaccessible with the radial velocity technique. In particular, SIM will search for planets around young stars providing insights into how planetary systems are born and evolve with time.

  2. Observed properties of extrasolar planets.

    PubMed

    Howard, Andrew W

    2013-05-03

    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.

  3. Kepler-77b: a very low albedo, Saturn-mass transiting planet around a metal-rich solar-like star

    NASA Astrophysics Data System (ADS)

    Gandolfi, D.; Parviainen, H.; Fridlund, M.; Hatzes, A. P.; Deeg, H. J.; Frasca, A.; Lanza, A. F.; Prada Moroni, P. G.; Tognelli, E.; McQuillan, A.; Aigrain, S.; Alonso, R.; Antoci, V.; Cabrera, J.; Carone, L.; Csizmadia, Sz.; Djupvik, A. A.; Guenther, E. W.; Jessen-Hansen, J.; Ofir, A.; Telting, J.

    2013-09-01

    We report the discovery of Kepler-77b (alias KOI-127.01), a Saturn-mass transiting planet in a 3.6-day orbit around a metal-rich solar-like star. We combined the publicly available Kepler photometry (quarters 1-13) with high-resolution spectroscopy from the Sandiford at McDonald and FIES at NOT spectrographs. We derived the system parameters via a simultaneous joint fit to the photometric and radial velocity measurements. Our analysis is based on the Bayesian approach and is carried out by sampling the parameter posterior distributions using a Markov chain Monte Carlo simulation. Kepler-77b is a moderately inflated planet with a mass of Mp = 0.430 ± 0.032 MJup, a radius of Rp = 0.960 ± 0.016 RJup, and a bulk density of ρp = 0.603 ± 0.055 g cm-3. It orbits a slowly rotating (Prot = 36 ± 6 days) G5 V star with M⋆ = 0.95 ± 0.04 M⊙, R⋆ = 0.99 ± 0.02 R⊙, Teff = 5520 ± 60 K, [M/H] = 0.20 ± 0.05 dex, that has an age of 7.5 ± 2.0 Gyr. The lack of detectable planetary occultation with a depth higher than ~10 ppm implies a planet geometric and Bond albedo of Ag ≤ 0.087 ± 0.008 and AB ≤ 0.058 ± 0.006, respectively, placing Kepler-77b among the gas-giant planets with the lowest albedo known so far. We found neither additional planetary transit signals nor transit-timing variations at a level of ~0.5 min, in accordance with the trend that close-in gas giant planets seem to belong to single-planet systems. The 106 transitsobserved in short-cadence mode by Kepler for nearly 1.2 years show no detectable signatures of the planet's passage in front of starspots. We explored the implications of the absence of detectable spot-crossing events for the inclination of the stellar spin-axis, the sky-projected spin-orbit obliquity, and the latitude of magnetically active regions. Based on observations obtained with the 2.1-m Otto Struve telescope at McDonald Observatory, Texas, USA.Based on observations obtained with the Nordic Optical Telescope, operated on the

  4. Kepler's Multiple Planet Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2012-01-01

    Among the 1800 Kepler targets that have candidate planets, 20% have two or more candidate planets. While most of these objects have not yet been confirmed as true planets, several considerations strongly suggest that the vast majority of these multi-candidate systems are true planetary systems. Virtually all candidate systems are stable, as tested by numerical integrations (assuming a nominal mass-radius relationship). Statistical studies performed on these candidates reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness of planetary systems. The distribution of observed period ratios shows that the vast majority of candidate pairs are neither in nor near low-order mean motion resonances. Nonetheless, there are small but statistically significant excesses of candidate pairs both in resonance and spaced slightly too far apart to be in resonance, particularly near the 2:1 resonance. The characteristics of the confirmed Kepler multi-planet systems will also be discussed.

  5. PREDICTING PLANETS IN KEPLER MULTI-PLANET SYSTEMS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-05-20

    We investigate whether any multi-planet systems among Kepler candidates (2011 February release) can harbor additional terrestrial-mass planets or smaller bodies. We apply the packed planetary systems hypothesis that suggests all planetary systems are filled to capacity, and use a Hill stability criterion to identify eight two-planet systems with significant gaps between the innermost and outermost planets. For each of these systems, we perform long-term numerical integrations of 10{sup 7} years to investigate the stability of 4000-8000 test particles injected into the gaps. We map out stability regions in orbital parameter space, and therefore quantify the ranges of semimajor axes and eccentricities of stable particles. Strong mean-motion resonances can add additional regions of stability in otherwise unstable parameter space. We derive simple expressions for the extent of the stability regions, which is related to quantities such as the dynamical spacing {Delta}, the separation between two planets in units of their mutual Hill radii. Our results suggest that planets with separation {Delta} < 10 are unlikely to host extensive stability regions, and that about 95 out of a total of 115 two-planet systems in the Kepler sample may have sizeable stability regions. We predict that Kepler candidate systems including KOI 433, KOI 72/Kepler-10, KOI 555, KOI 1596, KOI 904, KOI 223, KOI 1590, and KOI 139 can harbor additional planets or low-mass bodies between the inner and outer detected planets. These predicted planets may be detected by future observations.

  6. HAT-P-18b and HAT-P-19b: Two Low-density Saturn-mass Planets Transiting Metal-rich K Stars

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Sato, B.; Torres, G.; Noyes, R. W.; Latham, D. W.; Kovács, G.; Fischer, D. A.; Howard, A. W.; Johnson, J. A.; Marcy, G. W.; Buchhave, L. A.; Füresz, G.; Perumpilly, G.; Béky, B.; Stefanik, R. P.; Sasselov, D. D.; Esquerdo, G. A.; Everett, M.; Csubry, Z.; Lázár, J.; Papp, I.; Sári, P.

    2011-01-01

    We report the discovery of two new transiting extrasolar planets. HAT-P-18b orbits the V = 12.759 K2 dwarf star GSC 2594-00646, with a period P = 5.508023 ± 0.000006 days, transit epoch Tc = 2454715.02174 ± 0.00020 (BJD), and transit duration 0.1131 ± 0.0009 days. The host star has a mass of 0.77 ± 0.03 M sun, radius of 0.75 ± 0.04 R sun, effective temperature 4803 ± 80 K, and metallicity [Fe/H] = +0.10 ± 0.08. The planetary companion has a mass of 0.197 ± 0.013 M J and radius of 0.995 ± 0.052 R J, yielding a mean density of 0.25 ± 0.04 g cm-3. HAT-P-19b orbits the V = 12.901 K1 dwarf star GSC 2283-00589, with a period P = 4.008778 ± 0.000006 days, transit epoch Tc = 2455091.53417 ± 0.00034 (BJD), and transit duration 0.1182 ± 0.0014 days. The host star has a mass of 0.84 ± 0.04 M sun, radius of 0.82 ± 0.05 R sun, effective temperature 4990 ± 130 K, and metallicity [Fe/H] = +0.23 ± 0.08. The planetary companion has a mass of 0.292 ± 0.018 M J and radius of 1.132 ± 0.072 R J, yielding a mean density of 0.25 ± 0.04 g cm-3. The radial velocity residuals for HAT-P-19 exhibit a linear trend in time, which indicates the presence of a third body in the system. Comparing these observations with theoretical models, we find that HAT-P-18b and HAT-P-19b are each consistent with a hydrogen-helium-dominated gas giant planet with negligible core mass. HAT-P-18b and HAT-P-19b join HAT-P-12b and WASP-21b in an emerging group of low-density Saturn-mass planets, with negligible inferred core masses. However, unlike HAT-P-12b and WASP-21b, both HAT-P-18b and HAT-P-19b orbit stars with super-solar metallicity. This calls into question the heretofore suggestive correlation between the inferred core mass and host star metallicity for Saturn-mass planets. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO (A146Hr, A201Hr

  7. A Kepler Transiting Circumbinary Planet

    NASA Astrophysics Data System (ADS)

    Welsh, William F.; Orosz, J. A.; Fabrycky, D. C.; Haghighipour, N.; Short, D. R.; Kepler Team

    2014-01-01

    Among the thousands of planet candidates discovered by Kepler only a few have been detected in binary star systems. To date, seven transiting circumbinary planets have been confirmed, with several more candidates planets under investigation. Of the confirmed cases, the planets orbit short-period eclipsing binaries that have periods between one and seven weeks. The eclipsing binary nature of the stars allows their masses and radii to be accurately determined. Perturbations of the binary can be detected by eclipsing timing variations, sometimes allowing the mass of the planet to be measured. In this talk, we present the most recent Kepler transiting circumbinary planet. We gratefully acknowledge support from the NSF via grant AST-1109928, and from NASA via Kepler PSP grant NNX12AS23G and OSS grant NNX12AI76G.

  8. 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.

  9. 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.

  10. On collisional capture rates of irregular satellites around the gas-giant planets and the minimum mass of the solar nebula

    NASA Astrophysics Data System (ADS)

    Koch, F. Elliott; Hansen, Bradley M. S.

    2011-09-01

    We investigate the probability that an inelastic collision of planetesimals within the Hill sphere of the Jovian planets could explain the presence and orbits of observed irregular satellites. Capture of satellites via this mechanism is highly dependent on not only the mass of the protoplanetary disc, but also the shape of the planetesimal size distribution. We performed 2000 simulations for integrated time intervals ˜2 Myr and found that, given the currently accepted value for the minimum mass solar nebula and planetesimal number density based upon the Nesvorný et al. and Charnoz & Morbidelli size distribution dN˜D-3.5dD, the collision rates for the different Jovian planets range between ˜0.6 and ≳170 Myr-1 for objects with radii 1 km ≤r≤ 10 km. Additionally, we found that the probability that these collisions remove enough orbital energy to yield a bound orbit was ≲10-5 and had very little dependence on the relative size of the planetesimals. Of these collisions, the collision energy between two objects was ≳103 times the gravitational binding energy for objects with radii ˜100 km. We find that capturing irregular satellites via collisions between unbound objects can only account for ˜0.1 per cent of the observed population, hence this cannot be the sole method of producing irregular satellites.

  11. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Astrophysics Data System (ADS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.; Bhattacharya, A.; Koshimoto, N.; Suzuki, D.; Tristram, P. J.; Han, C.; Gould, A.; Pogge, R.; Yee, J.

    2016-06-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 ± 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B&C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of a ˜4-9 Gyr lens star of M lens = 1.06 ± 0.05 M ⊙ at a distance of D lens = 4.0 ± 0.3 kpc, orbited by two giant planets of 0.145 ± 0.008 M Jup and 0.86 ± 0.06 M Jup, with projected separations of 4.0 ± 0.5 au and 4.8 ± 0.7 au, respectively. Because the lens is brighter than the source star by 16 ± 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  12. A Quantitative Criterion for Defining Planets

    NASA Astrophysics Data System (ADS)

    Margot, Jean-Luc

    2015-12-01

    A simple metric can be used to determine whether a planet or exoplanet can clear its orbital zone during a characteristic time scale, such as the lifetime of the host star on the main sequence. This criterion requires only estimates of star mass, planet mass, and orbital period, making it possible to immediately classify 99% of all known exoplanets. All eight planets and all classifiable exoplanets satisfy the criterion. This metric may be useful in generalizing and simplifying the definition of a planet.

  13. A Quantitative Criterion for Defining Planets

    NASA Astrophysics Data System (ADS)

    Margot, J. L.

    2015-12-01

    A simple metric can be used to determine whether a planet or exoplanet can clear its orbital zone during a characteristic time scale, such as the lifetime of the host star on the main sequence. This criterion requires only estimates of star mass, planet mass, and orbital period, making it possible to immediately classify 99% of all known exoplanets. All 8 planets and all classifiable exoplanets satisfy the criterion. This metric may be useful in generalizing and simplifying the definition of a planet.

  14. The Metallicity of Giant Planets

    NASA Astrophysics Data System (ADS)

    Thorngren, Daniel P.; Fortney, Jonathan

    2015-12-01

    Unique clues about the formation processes of giant planets can be found in their bulk compositions. Transiting planets provide us with bulk density determinations that can then be compared to models of planetary structure and evolution, to deduce planet bulk metallicities. At a given mass, denser planets have a higher mass fraction of metals. However, the unknown hot Jupiter "radius inflation" mechanism leads to under-dense planets that severely biases this work. Here we look at cooler transiting gas giants (Teff < 1000 K), which do not exhibit the radius inflation effect seen in their warmer cousins. We identified 40 such planets between 20 M_Earth and 20 M_Jup from the literature and used evolution models to determine their bulk heavy-element ("metal") mass. Several important trends are apparent. We see that all planets have at least ~10 M_Earth of metals, and that the mass of metal correlates strongly with the total mass of the planet. The heavy-element mass goes as the square root of the total mass. Both findings are consistent with the core accretion model. We also examined the effect of the parent star metallicity [Fe/H], finding that planets around high-metallicity stars are more likely to have large amounts of metal, but the relation appears weaker than previous studies with smaller sample sizes had suggested. We also looked for connections between bulk composition and planetary orbital parameters and stellar parameters, but saw no pattern, which is also an important result. This work can be directly compared to current and future outputs from planet formation models, including population synthesis.

  15. Inside-out planet formation

    SciTech Connect

    Chatterjee, Sourav; Tan, Jonathan C. E-mail: jt@astro.ufl.edu

    2014-01-01

    The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M {sub ⊕} planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

  16. ALMA observations of the nearby AGB star L2 Puppis. I. Mass of the central star and detection of a candidate planet

    NASA Astrophysics Data System (ADS)

    Kervella, P.; Homan, W.; Richards, A. M. S.; Decin, L.; McDonald, I.; Montargès, M.; Ohnaka, K.

    2016-12-01

    Six billion years from now, while evolving on the asymptotic giant branch (AGB), the Sun will metamorphose from a red giant into a beautiful planetary nebula. This spectacular evolution will impact the solar system planets, but observational confirmations of the predictions of evolution models are still elusive as no planet orbiting an AGB star has yet been discovered. The nearby AGB red giant L2 Puppis (d = 64 pc) is surrounded by an almost edge-on circumstellar dust disk. We report new observations with ALMA at very high angular resolution (18 × 15 mas) in band 7 (ν ≈ 350 GHz) that allow us to resolve the velocity profile of the molecular disk. We establish that the gas velocity profile is Keplerian within the central cavity of the dust disk, allowing us to derive the mass of the central star L2 Pup A, mA = 0.659 ± 0.011 ± 0.041 M⊙ (± 6.6%). From evolutionary models, we determine that L2 Pup A had a near-solar main-sequence mass, and is therefore a close analog of the future Sun in 5 to 6 Gyr. The continuum map reveals a secondary source (B) at a radius of 2 AU contributing fB/fA = 1.3 ± 0.1% of the flux of the AGB star. L2 Pup B is also detected in CO emission lines at a radial velocity of vB = 12.2 ± 1.0 km s-1. The close coincidence of the center of rotation of the gaseous disk with the position of the continuum emission from the AGB star allows us to constrain the mass of the companion to mB = 12 ± 16 MJup. L2 Pup B is most likely a planet or low-mass brown dwarf with an orbital period of about five years. Its continuum brightness and molecular emission suggest that it may be surrounded by an extended molecular atmosphere or an accretion disk. L2 Pup therefore emerges as a promising vantage point on the distant future of our solar system.

  17. Prospects for Planet Detection with SIM

    NASA Astrophysics Data System (ADS)

    Catanzarite, Joseph; Law, N.; Shao, M.; Unwin, S.; Edberg, S.

    2007-07-01

    SIM is an optical Michelson interferometer with a 9-meter baseline, with angular precision of 1 microarcsecond in a single measurement. SIM's direct measurement of the stellar astrometric reflex motion due to a planetary companion permits accurate orbit determination, giving eccentricity and inclination, and most importantly, unambiguous measurement of the planet mass. SIM is the only mission that is * Sensitive to detection of planets across nearly the entire range of masses and orbit periods where terrestrial planets form and evolve. * Capable of detecting and confirming rocky planets in the habitable zones of nearby solar-type stars We present results o