Showing papers in "The Astronomical Journal in 2020"
Lund University1, Malmö University2, New Mexico State University3, Spanish National Research Council4, University of La Laguna5, University of Arizona6, University of Utah7, University of Texas at Austin8, University of Colorado Boulder9, Sternberg Astronomical Institute10, Apache Corporation11, Uppsala University12, University of Virginia13, Eötvös Loránd University14, Universidade Federal de Sergipe15, Carnegie Learning16, Princeton University17, University of Toronto18, Texas Christian University19, Ohio State University20, University of Washington21
TL;DR: The spectral analysis and data products in Data Release 16 (DR16; 2019 December) from the high-resolution near-infrared Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2/Sloan Digital Sky Survey (SDSS)-IV survey are described in this article.
Abstract: The spectral analysis and data products in Data Release 16 (DR16; 2019 December) from the high-resolution near-infrared Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2/Sloan Digital Sky Survey (SDSS)-IV survey are described. Compared to the previous APOGEE data release (DR14; 2017 July), APOGEE DR16 includes about 200,000 new stellar spectra, of which 100,000 are from a new southern APOGEE instrument mounted on the 2.5 m du Pont telescope at Las Campanas Observatory in Chile. DR16 includes all data taken up to 2018 August, including data released in previous data releases. All of the data have been re-reduced and re-analyzed using the latest pipelines, resulting in a total of 473,307 spectra of 437,445 stars. Changes to the analysis methods for this release include, but are not limited to, the use of MARCS model atmospheres for calculation of the entire main grid of synthetic spectra used in the analysis, a new method for filling "holes"in the grids due to unconverged model atmospheres, and a new scheme for continuum normalization. Abundances of the neutron-capture element Ce are included for the first time. A new scheme for estimating uncertainties of the derived quantities using stars with multiple observations has been applied, and calibrated values of surface gravities for dwarf stars are now supplied. Compared to DR14, the radial velocities derived for this release more closely match those in the Gaia DR2 database, and a clear improvement in the spectral analysis of the coolest giants can be seen. The reduced spectra as well as the result of the analysis can be downloaded using links provided on the SDSS DR16 web page. (Less)
209 citations
188 citations
TL;DR: The Gaia-Kepler Stellar Properties Catalog as mentioned in this paper is a set of stellar properties of 186,301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available.
Abstract: An accurate and precise Kepler Stellar Properties Catalog is essential for the interpretation of the Kepler exoplanet survey results. Previous Kepler Stellar Properties Catalogs have focused on reporting the best-available parameters for each star, but this has required combining data from a variety of heterogeneous sources. We present the Gaia-Kepler Stellar Properties Catalog, a set of stellar properties of 186,301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available. Our photometric effective temperatures, derived from $g-K_s$ colors, are calibrated on stars with interferometric angular diameters. Median catalog uncertainties are 112 K for $T_{\mathrm{eff}}$, 0.05 dex for $\log g$, 4% for $R_\star$, 7% for $M_\star$, 13% for $\rho_\star$, 10% for $L_\star$, and 56% for stellar age. These precise constraints on stellar properties for this sample of stars will allow unprecedented investigations into trends in stellar and exoplanet properties as a function of stellar mass and age. In addition, our homogeneous parameter determinations will permit more accurate calculations of planet occurrence and trends with stellar properties.
146 citations
TL;DR: In this article, the authors derived analytic closed-form solutions for the light curve of a planet transiting a star with a limb darkening profile which is a polynomial function of the stellar elevation, up to arbitrary integer order.
Abstract: We derive analytic, closed-form solutions for the light curve of a planet transiting a star with a limb darkening profile which is a polynomial function of the stellar elevation, up to arbitrary integer order. We provide improved analytic expressions for the uniform, linear, and quadratic limb-darkened cases, as well as novel expressions for higher order integer powers of limb darkening. The formulae are crafted to be numerically stable over the expected range of usage. We additionally present analytic formulae for the partial derivatives of instantaneous flux with respect to the radius ratio, impact parameter, and limb darkening coefficients. These expressions are rapid to evaluate, and compare quite favorably in speed and accuracy to existing transit light curve codes. We also use these expressions to numerically compute the first partial derivatives of exposure-time averaged transit light curves with respect to all model parameters. An additional application is modeling eclipsing binary or eclipsing multiple star systems in cases where the stars may be treated as spherically symmetric. We provide code which implements these formulae in C++, Python, IDL, and Julia, with tests and examples of usage.
112 citations
TL;DR: In this article, the authors re-compute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age, and find evidence of a stellar age dependence of the planet populations straddling the radius valley.
Abstract: Studies of exoplanet demographics require large samples and precise constraints on exoplanet host stars. Using the homogeneous Kepler stellar properties derived using Gaia Data Release 2 by Berger et al. (2020), we re-compute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age. We measure the stellar mass dependence of the planet radius valley to be $d \log R_{\mathrm{p}}$/$d \log M_\star = 0.26^{+0.21}_{-0.16}$, consistent with the slope predicted by a planet mass dependence on stellar mass ($0.24-0.35$) and core-powered mass-loss (0.33). We also find first evidence of a stellar age dependence of the planet populations straddling the radius valley. Specifically, we determine that the fraction of super-Earths ($1-1.8 \mathrm{R_\oplus}$) to sub-Neptunes ($1.8-3.5 \mathrm{R_\oplus}$) increases from $0.61 \pm 0.09$ at young ages ( 1 Gyr), consistent with the prediction by core-powered mass-loss that the mechanism shaping the radius valley operates over Gyr timescales. Additionally, we find a tentative decrease in the radii of relatively cool ($F_{\mathrm{p}} 650 \mathrm{F_\oplus}$) and show that these planets are preferentially orbiting more evolved stars compared to other planets at similar incident fluxes. In addition, we identify candidates for cool ($F_{\mathrm{p}} < 20 \mathrm{F_\oplus}$) inflated Jupiters, present a revised list of habitable zone candidates, and find that the ages of single- and multiple-transiting planet systems are statistically indistinguishable.
98 citations
TL;DR: In this article, the authors combine high-contrast imaging observations of substellar companions obtained primarily with Keck/NIRC2 together with astrometry from the literature to test for differences in the population level eccentricity distributions of 27 long-period giant planets and brown dwarf companions between 5 and 100 au using hierarchical Bayesian modeling.
Abstract: The orbital eccentricities of directly imaged exoplanets and brown dwarf companions provide clues about their formation and dynamical histories. We combine new high-contrast imaging observations of substellar companions obtained primarily with Keck/NIRC2 together with astrometry from the literature to test for differences in the population-level eccentricity distributions of 27 long-period giant planets and brown dwarf companions between 5 and 100 au using hierarchical Bayesian modeling. Orbit fits are performed in a uniform manner for companions with short orbital arcs; this typically results in broad constraints for individual eccentricity distributions, but together as an ensemble, these systems provide valuable insight into their collective underlying orbital patterns. The shape of the eccentricity distribution function for our full sample of substellar companions is approximately flat from e = 0–1. When subdivided by companion mass and mass ratio, the underlying distributions for giant planets and brown dwarfs show significant differences. Low mass ratio companions preferentially have low eccentricities, similar to the orbital properties of warm Jupiters found with radial velocities and transits. We interpret this as evidence for in situ formation on largely undisturbed orbits within massive extended disks. Brown dwarf companions exhibit a broad peak at e ≈ 0.6–0.9 with evidence for a dependence on orbital period. This closely resembles the orbital properties and period-eccentricity trends of wide (1–200 au) stellar binaries, suggesting that brown dwarfs in this separation range predominantly form in a similar fashion. We also report evidence that the "eccentricity dichotomy" observed at small separations extends to planets on wide orbits: the mean eccentricity for the multi-planet system HR 8799 is lower than for systems with single planets. In the future, larger samples and continued astrometric orbit monitoring will help establish whether these eccentricity distributions correlate with other parameters such as stellar host mass, multiplicity, and age.
89 citations
TL;DR: In this article, the occurrence rate of small close-in planets around low-mass dwarf stars using the known planet populations from the Kepler and K2 missions was analyzed and the slope of the radius valley was shown to be $r{p,\text{valley}} \propto F^{-0.060\pm 0.025}$ which bears the opposite sign from that measured around Sun-like stars.
Abstract: We present calculations of the occurrence rate of small close-in planets around low mass dwarf stars using the known planet populations from the $Kepler$ and $K2$ missions. Applying completeness corrections clearly reveals the radius valley in the maximum a-posteriori occurrence rates as a function of orbital separation and planet radius. We measure the slope of the valley to be $r_{p,\text{valley}} \propto F^{-0.060\pm 0.025}$ which bears the opposite sign from that measured around Sun-like stars thus suggesting that thermally driven atmospheric mass loss may not dominate the evolution of planets in the low stellar mass regime or that we are witnessing the emergence of a separate channel of planet formation. The latter notion is supported by the relative occurrence of rocky to non-rocky planets increasing from $0.5\pm 0.1$ around mid-K dwarfs to $8.5\pm 4.6$ around mid-M dwarfs. Furthermore, the center of the radius valley at $1.54\pm 0.16$ R$_{\oplus}$ is shown to shift to smaller sizes with decreasing stellar mass in agreement with physical models of photoevaporation, core-powered mass loss, and gas-poor formation. Although current measurements are insufficient to robustly identify the dominant formation pathway of the radius valley, such inferences may be obtained by $TESS$ with $\mathcal{O}(85,000)$ mid-to-late M dwarfs observed with 2-minute cadence. The measurements presented herein also precisely designate the subset of planetary orbital periods and radii that should be targeted in radial velocity surveys to resolve the rocky to non-rocky transition around low mass stars.
89 citations
Texas Christian University1, University of Arizona2, University of Concepción3, Spanish National Research Council4, University of La Laguna5, University of La Serena6, University of Barcelona7, Carnegie Learning8, Princeton University9, Apache Corporation10, Sternberg Astronomical Institute11, University of Utah12, INAF13, Leibniz Institute for Astrophysics Potsdam14, Space Telescope Science Institute15, Lund University16, Malmö University17, University of Atacama18, Pontifical Catholic University of Chile19, University of Virginia20, Andrés Bello National University21, University of Washington22
TL;DR: SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Institutes of Health (NIH), and the U.S. Department of Energy Office of Science as discussed by the authors.
Abstract: comments.
J.D. and P.M.F. acknowledge support for this research from the
National Science Foundation (AST-1311835 & AST-1715662).
K.C. acknowledges support for this research from the National
Science Foundation (AST-0907873).
D.A.G.H. acknowledges support from the State Research
Agency (AEI) of the Spanish Ministry of Science, Innovation,
and Universities (MCIU), and the European Regional Development Fund (FEDER) under grant AYA2017-88254-P.
D.G. and D.M. gratefully acknowledge support from the
Chilean Centro de Excelencia en Astrofisica y Tecnologias Afines
(CATA) BASAL grant AFB-170002. D.G. also acknowledges
financial support from the Direccion de Investigacion y Desarrollo
de la Universidad de La Serena through the Programa de
Incentivo a la Investigacion de Academicos (PIA-DIDULS). D.M.
is also supported by the Programa Iniciativa Cientifica Milenio grant IC120009, awarded to the Millennium Institute of
Astrophysics (MAS), and by Proyecto FONDECYT regular No.
1170121.
H.J. acknowledges support from the Crafoord Foundation,
Stiftelsen Olle Engkvist Byggmastare, and Ruth och Nils-Erik
Stenbacks stiftelse.
A.R.-L. acknowledges financial support provided in Chile by
Comision Nacional de Investigacion Cientifica y Tecnologica
(CONICYT) through the FONDECYT project 1170476 and by
the QUIMAL project 130001
Funding for SDSS-III has been provided by the Alfred P.
Sloan Foundation, the Participating Institutions, the National
Science Foundation, and the U.S. Department of Energy Office
of Science. The SDSS-III website is http://www.sdss3.org/.
SDSS-III is managed by the Astrophysical Research
Consortium for the Participating Institutions of the SDSS-III
Collaboration including the University of Arizona, the
Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the
French Participation Group, the German Participation Group,
Harvard University, the Instituto de Astrofisica de Canarias, the
Michigan State/Notre Dame/JINA Participation Group, Johns
Hopkins University, Lawrence Berkeley National Laboratory,
Max Planck Institute for Astrophysics, Max Planck Institute for
Extraterrestrial Physics, New Mexico State University, New
York University, Ohio State University, Pennsylvania State
University, University of Portsmouth, Princeton University, the
Spanish Participation Group, University of Tokyo, University
of Utah, Vanderbilt University, University of Virginia,
University of Washington, and Yale University.
Funding for the Sloan Digital Sky Survey IV has been provided
by the Alfred P. Sloan Foundation, the U.S. Department of
Energy Office of Science, and the Participating Institutions.
SDSS-IV acknowledges support and resources from the Center
for High-Performance Computing at the University of Utah. The
SDSS website is www.sdss.org.
82 citations
University of Maryland, College Park1, Arizona State University2, Goddard Space Flight Center3, California Institute of Technology4, Princeton University5, University of California, Santa Cruz6, Johns Hopkins University7, Université de Montréal8, Space Telescope Science Institute9, Cornell University10, University of Cambridge11, Johns Hopkins University Applied Physics Laboratory12
TL;DR: In this paper, the authors report 78 secondary eclipse depths for a sample of 36 transiting hot Jupiters observed at 3.6 and 4.5 μm using the Spitzer Space Telescope.
Abstract: We report 78 secondary eclipse depths for a sample of 36 transiting hot Jupiters observed at 3.6 and 4.5 μm using the Spitzer Space Telescope. Our eclipse results for 27 of these planets are new, and include highly irradiated worlds such as KELT-7b, WASP-87b, WASP-76b, and WASP-64b, and important targets for James Webb Space Telescope such as WASP-62b. We find that WASP-62b has a slightly eccentric orbit (e cos ω = 0.00614±0.00064), and we confirm the eccentricity of HAT-P-13b and WASP-14b. The remainder are individually consistent with circular orbits, but we find statistical evidence for eccentricity increasing with orbital period in our range from 1 to 5 days. Our day-side brightness temperatures for the planets yield information on albedo and heat redistribution, following Cowan & Agol (2011). Planets having maximum day-side temperatures exceeding ~2200 K are consistent with having zero albedo and a distribution of stellar irradiance uniformly over the day-side hemisphere. Our most intriguing result is that we detect a systematic difference between the emergent spectra of these hot Jupiters as compared to blackbodies. The ratio of observed brightness temperatures, Tb(4.5)/Tb(3.6), increases with equilibrium temperature by 100 ± 24 parts-per-million per Kelvin, over the entire temperature range in our sample (800–2500 K). No existing model predicts this trend over such a large range of temperature. We suggest that this may be due to a structural difference in the atmospheric temperature profiles of real planetary atmospheres as compared to models.
82 citations
University of North Carolina at Chapel Hill1, Las Cumbres Observatory Global Telescope Network2, University of Texas at Austin3, Dartmouth College4, Smithsonian Institution5, California Institute of Technology6, INAF7, University of Geneva8, University of Cambridge9, University of St Andrews10, Technical University of Denmark11, University of Oxford12, University of California, Riverside13, University of California, Santa Barbara14, Massachusetts Institute of Technology15, Princeton University16, Ames Research Center17, University of Maryland, Baltimore County18, Goddard Space Flight Center19, Search for extraterrestrial intelligence20, University of New Mexico21
TL;DR: In this paper, the authors used the National Science Foundation Graduate Research Fellowship Program (GRF) under grant No. DGE-1650116 to support the work of P.A.W.V.
Abstract: A.W.M. was supported through NASA's Astrophysics Data Analysis Program (80NSSC19K0583). M.L.W. was supported by a grant through NASA's K2 GO program (80NSSC19K0097). This material is based on work supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1650116 to P.C.T. A.V.'s work was performed under contract with the California Institute of Technology/Jet Propulsion Laboratory funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. D.D. acknowledges support from NASA through Caltech/JPL grant RSA-1006130 and through the TESS Guest Investigator Program grant 80NSSC19K1727.
80 citations
TL;DR: In this article, the authors explore the use of the baryonic Tully-Fisher relation (bTFR) as a new distance indicator, using 50 galaxies with accurate distances from Cepheids or the tip magnitude of the red giant branch.
Abstract: We explore the use of the baryonic Tully–Fisher relation (bTFR) as a new distance indicator. Advances in near-IR imaging and stellar population models, plus precise rotation curves, have reduced the scatter in the bTFR such that distance is the dominant source of uncertainty. Using 50 galaxies with accurate distances from Cepheids or the tip magnitude of the red giant branch, we calibrate the bTFR on a scale independent of H o . We then apply this calibrated bTFR to 95 independent galaxies from the SPARC sample, using CosmicFlows-3 velocities, to deduce the local value of H o . We find H o = 75.1 ± 2.3 (stat) ±1.5 (sys) km s−1 Mpc−1.
Leibniz Institute for Astrophysics Potsdam1, Lund University2, Centre national de la recherche scientifique3, University of Ljubljana4, Australian National University5, Johns Hopkins University6, University of Virginia7, University of Strasbourg8, University of Southern Queensland9, Australian Astronomical Observatory10, University of Hull11, University of Cambridge12, Heidelberg University13, Kapteyn Astronomical Institute14, Saint Martin's University15, INAF16, University of Victoria17, University of Hong Kong18, University of Sydney19, Macquarie University20, University College London21, University of Padua22, Department of Industry23, Kavli Institute for Theoretical Physics24, University of Barcelona25, University of Porto26, Université Paris-Saclay27, Paris Diderot University28, University of Birmingham29, Aarhus University30, Max Planck Society31, Diego Portales University32, University of La Laguna33, Spanish National Research Council34
TL;DR: In this article, the authors presented the Rave project, which was provided by the Leibniz-Institut f¨ur Astrophysik Potsdam (AIP), the Australian Astronomical Observatory, the Australian National University; the Australian Research Council; the French National Research Agency (PNCG) of CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES); the German ResearchFoundation (SPP 1177 and SFB 881); the European Research Council (ERC-StG
Abstract: Funding for Rave has been provided by: the Leibniz-Institut f¨ur Astrophysik Potsdam (AIP);
the Australian Astronomical Observatory; the Australian National University; the Australian Research Council; the French National Research Agency (Programme National Cosmology et Galaxies
(PNCG) of CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES); the German Research
Foundation (SPP 1177 and SFB 881); the European Research Council (ERC-StG 240271 Galactica);
the Istituto Nazionale di Astrofisica at Padova; The Johns Hopkins University; the National Science
Foundation of the USA (AST-0908326); the W. M. Keck foundation; the Macquarie University; the
Netherlands Research School for Astronomy; the Natural Sciences and Engineering Research Council of Canada; the Slovenian Research Agency (research core funding no. P1-0188); the Swiss National
Science Foundation; the Science & Technology Facilities Council of the UK; Opticon; Strasbourg
Observatory; and the Universities of Basel, Groningen, Heidelberg, and Sydney. PJM is supported
by grant 2017-03721 from the Swedish Research Council. LC is the recipient of the ARC Future
Fellowship FT160100402. RAG acknowledges the support from the PLATO CNES grant. SM would
like to acknowledge support from the Spanish Ministry with the Ramon y Cajal fellowship number
RYC-2015-17697. MS thanks the Research School of Astronomy & Astrophysics in Canberra for
support through a Distinguished Visitor Fellowship. RFGW thanks the Kavli Institute for Theoretical Physics and the Simons Foundation for support as a Simons Distinguished Visiting Scholar.
This research was supported in part by the National Science Foundation under Grant No. NSF
PHY-1748958 to KITP.
TL;DR: In this article, the results from the LBTI/Hunt for Observable Signatures of Terrestrial Systems survey for exozodiacal dust were analyzed and a 1σ median sensitivity of 23 zodis times the solar system dust surface density in its habitable zone (HZ) was estimated.
Abstract: The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 μm) to suppress a star's bright light and probe for faint circumstellar emission. We present and statistically analyze the results from the LBTI/Hunt for Observable Signatures of Terrestrial Systems survey for exozodiacal dust. By comparing our measurements to model predictions based on the solar zodiacal dust in the N band, we estimate a 1σ median sensitivity of 23 zodis times the solar system dust surface density in its habitable zone (HZ; 23 zodis) for early-type stars and 48 zodis for Sun-like stars, where 1 zodi is the surface density of HZ dust in the solar system. Of the 38 stars observed, 10 show significant excess. A clear correlation of our detections with the presence of cold dust in the systems was found, but none with the stellar spectral type or age. The majority of Sun-like stars have relatively low HZ dust levels (best-fit median: 3 zodis, 1σ upper limit: 9 zodis, 95% confidence: 27 zodis based on our N band measurements), while ~20% are significantly more dusty. The solar system's HZ dust content is consistent with being typical. Our median HZ dust level would not be a major limitation to the direct imaging search for Earth-like exoplanets, but more precise constraints are still required, in particular to evaluate the impact of exozodiacal dust for the spectroscopic characterization of imaged exo-Earth candidates.
TL;DR: In this article, a transiting hot Jupiter was discovered orbiting HIP 67522 in the 10-20 Myr old Sco-Cen OB association, with an orbital period of 6.9596$+0.000016} and radius of 10.23$ days.
Abstract: We present the discovery of a transiting hot Jupiter orbiting HIP 67522 ($T_{eff}\sim5650$ K; $M_* \sim 1.2 M_{\odot}$) in the 10-20 Myr old Sco-Cen OB association. We identified the transits in the TESS data using our custom notch-filter planet search pipeline, and characterize the system with additional photometry from Spitzer, spectroscopy from SOAR/Goodman, SALT/HRS, LCOGT/NRES, and SMARTS/CHIRON, and speckle imaging from SOAR/HRCam. We model the photometry as a periodic Gaussian process with transits to account for stellar variability, and find an orbital period of 6.9596$^{+0.000016}_{-0.000015}$ days and radius of 10.02$^{+0.54}_{-0.53}$ R$_\oplus$. We also identify a single transit of an additional candidate planet with radius 8.01$^{+0.75}_{-0.71}$ R$_\oplus$ that has an orbital period of $\gtrsim23$ days. The validated planet HIP 67522 b is currently the youngest transiting hot Jupiter discovered and is an ideal candidate for transmission spectroscopy and radial velocity follow-up studies, while also demonstrating that some young giant planets either form in situ at small orbital radii, or else migrate promptly from formation sites farther out in the disk.
Leibniz Institute for Astrophysics Potsdam1, University of Ljubljana2, Lund University3, Australian National University4, Johns Hopkins University5, University of Virginia6, University of Strasbourg7, University of Oxford8, Australian Astronomical Observatory9, University of Southern Queensland10, University of Hull11, University of Cambridge12, Heidelberg University13, University of Groningen14, Saint Martin's University15, INAF16, University of Victoria17, University of Hong Kong18, University of Sydney19, University College London20, University of Padua21, Department of Industry22, University of California, Santa Barbara23, University of Barcelona24, University of Porto25, Université Paris-Saclay26, University of Paris27, University of Birmingham28, Aarhus University29, Max Planck Society30, Diego Portales University31, University of La Laguna32, University of Potsdam33, Paris Diderot University34
TL;DR: In this paper, the authors presented the Rave project, which was supported by the Leibniz-Institut f¨ur Astrophysik Potsdam (AIP), the Australian Astronomical Observatory, the Australian National University; the Australian Research Council; the French National Research Agency (Programme National Cosmology et Galaxies (PNCG) of CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES); the German Research Foundation (SPP 1177 and SFB 881); the
Abstract: Funding for Rave has been provided by: the Leibniz-Institut f¨ur Astrophysik Potsdam (AIP); the Australian Astronomical Observatory; the Australian National University; the Australian Research Council; the French National Research Agency (Programme National Cosmology et Galaxies (PNCG) of CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES); the German Research Foundation (SPP 1177 and SFB 881); the European Research Council (ERC-StG 240271 Galactica); the Istituto Nazionale di Astrofisica at Padova; The Johns Hopkins University; the National Science Foundation of the USA (AST-0908326); the W. M. Keck foundation; the Macquarie University; the Netherlands Research School for Astronomy; the Natural Sciences and Engineering Research Council of Canada; the Slovenian Research Agency (research core funding no. P1-0188); the Swiss National Science Foundation; the Science & Technology Facilities Council of the UK; Opticon; Strasbourg Observatory; and the Universities of Basel, Groningen, Heidelberg, and Sydney. PJM is supported by grant 2017-03721 from the Swedish Research Council. LC is the recipient of the ARC Future Fellowship FT160100402. RAG acknowledges the support from the PLATO CNES grant. SM would like to acknowledge support from the Spanish Ministry with the Ramon y Cajal fellowship number RYC-2015-17697. MS thanks the Research School of Astronomy & Astrophysics in Canberra for support through a Distinguished Visitor Fellowship. RFGW thanks the Kavli Institute for Theoretical Physics and the Simons Foundation for support as a Simons Distinguished Visiting Scholar. This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958 to KITP.
TL;DR: orbitize! as discussed by the authors is an open-source, object-oriented software package for fitting the orbits of directly imaged objects, which is intended to be navigable by both orbit-fitting novices and seasoned experts.
Abstract: orbitize! is an open-source, object-oriented software package for fitting the orbits of directly imaged objects. It packages the Orbits for the Impatient (OFTI) algorithm and a parallel-tempered Markov Chain Monte Carlo (MCMC) algorithm into a consistent and intuitive Python API. orbitize! makes it easy to run standard astrometric orbit fits; in less than 10 lines of code, users can read in data, perform one fit using OFTI and another using MCMC, and make two publication-ready figures. Extensive pedagogical tutorials, intended to be navigable by both orbit-fitting novices and seasoned experts, are available on our documentation page. We have designed the orbitize! API to be flexible and easy to use/modify for unique cases. orbitize! was designed by members of the exoplanet imaging community to be a central repository for algorithms, techniques, and know-how developed by this community. We intend for it to continue to expand and change as the field progresses and new techniques are developed, and call for community involvement in this process. Complete and up-to-date documentation is available at orbitize.info, and the source code is available at github.com/sblunt/orbitize.
TL;DR: In this paper, a method for the probabilistic inference of the inclination of a star's rotation axis based on independent data sets that constrain the star rotation velocity and its projection onto our line of sight is presented.
Abstract: It is possible to learn about the orientation of a star's rotation axis by combining measurements of the star's rotation velocity ($v$) and its projection onto our line of sight ($v\sin i$). This idea has found many applications, including the investigation of the obliquities of stars with transiting planets. Here, we present a method for the probabilistic inference of the inclination of the star's rotation axis based on independent data sets that constrain $v$ and $v\sin i$. We also correct several errors and misconceptions that appear in the literature.
Ames Research Center1, University of British Columbia2, Goddard Space Flight Center3, Search for extraterrestrial intelligence4, Aarhus University5, University of California, Santa Cruz6, Carnegie Institution for Science7, Technical University of Denmark8, Massachusetts Institute of Technology9, Lawrence Livermore National Laboratory10, University of Birmingham11, NASA Exoplanet Science Institute12, University of Texas at Austin13, Lowell Observatory14, Smithsonian Institution15, California Institute of Technology16, Smithsonian Astrophysical Observatory17, Space Telescope Science Institute18, University of California, Berkeley19, Marshall Space Flight Center20, Spanish National Research Council21, University of La Laguna22, University of Southern California23, Villanova University24, Brigham Young University25, Carnegie Learning26, Jacobs Engineering Group27, University of Nevada, Las Vegas28, National Science Foundation29, San Diego State University30
TL;DR: In this article, the authors presented the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets, and they found that the HZ occurrence of planets with radius between 0.5 and 1.5 R orbiting stars with effective temperatures between 4800 K and 6300 K. They also presented occurrence rates for various stellar populations and planet size ranges.
Abstract: We present occurrence rates for rocky planets in the habitable zones (HZ) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η⊕ as the HZ occurrence of planets with radius between 0.5 and 1.5 R⊕ orbiting stars with effective temperatures between 4800 K and 6300 K. We find that η⊕ for the conservative HZ is between 0.37^(+0.48)_(−0.21) (errors reflect 68% credible intervals) and 0.60^(+0.90)_(−0.36) planets per star, while the optimistic HZ occurrence is between 0.58^(+0.73)_(−0.33) and 0.88^(+1.28)_(−0.51) planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates using both a Poisson likelihood Bayesian analysis and Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is about 6 pc away, and there are about 4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun.
TL;DR: In this article, the authors measured the WFC3 transmission spectra to be featureless between 1.15 and 1.63 μm, ruling out any variations greater than 0.6 scale heights (assuming a H/Hedominated atmosphere), thus showing no significant water absorption features.
Abstract: The Kepler mission revealed a class of planets known as "super-puffs," with masses only a few times larger than Earth's but radii larger than Neptune, giving them very low mean densities. All three of the known planets orbiting the young solar-type star Kepler 51 are super-puffs. The Kepler 51 system thereby provides an opportunity for a comparative study of the structures and atmospheres of this mysterious class of planets, which may provide clues about their formation and evolution. We observed two transits each of Kepler 51b and 51d with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope. Combining new WFC3 transit times with reanalyzed Kepler data and updated stellar parameters, we confirmed that all three planets have densities lower than 0.1 g cm⁻³. We measured the WFC3 transmission spectra to be featureless between 1.15 and 1.63 μm, ruling out any variations greater than 0.6 scale heights (assuming a H/He-dominated atmosphere), thus showing no significant water absorption features. We interpreted the flat spectra as the result of a high-altitude aerosol layer (pressure <3 mbar) on each planet. Adding this new result to the collection of flat spectra that have been observed for other sub-Neptune planets, we find support for one of the two hypotheses introduced by Crossfield & Kreidberg, that planets with cooler equilibrium temperatures have more high-altitude aerosols. We strongly disfavor their other hypothesis that the H/He mass fraction drives the appearance of large-amplitude transmission features.
TL;DR: In this article, the discovery and validation of a three-planar system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135) was presented.
Abstract: We present the discovery and validation of a three-planet system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135). TOI-700 lies in the TESS continuous viewing zone in the Southern Ecliptic Hemisphere; observations spanning 11 sectors reveal three planets with radii ranging from 1 R_⊕ to 2.6 R_⊕ and orbital periods ranging from 9.98 to 37.43 days. Ground-based follow-up combined with diagnostic vetting and validation tests enable us to rule out common astrophysical false-positive scenarios and validate the system of planets. The outermost planet, TOI-700 d, has a radius of 1.19 ± 0.11 R_⊕ and resides in the conservative habitable zone of its host star, where it receives a flux from its star that is approximately 86% of the Earth's insolation. In contrast to some other low-mass stars that host Earth-sized planets in their habitable zones, TOI-700 exhibits low levels of stellar activity, presenting a valuable opportunity to study potentially-rocky planets over a wide range of conditions affecting atmospheric escape. While atmospheric characterization of TOI-700 d with the James Webb Space Telescope (JWST) will be challenging, the larger sub-Neptune, TOI-700 c (R = 2.63 R_⊕), will be an excellent target for JWST and beyond. TESS is scheduled to return to the Southern Hemisphere and observe TOI-700 for an additional 11 sectors in its extended mission, which should provide further constraints on the known planet parameters and searches for additional planets and transit timing variations in the system.
University of California, Berkeley1, Search for extraterrestrial intelligence2, University of California, Los Angeles3, California Institute of Technology4, University of Grenoble5, Arizona State University6, Space Telescope Science Institute7, Stanford University8, University of Western Ontario9, University of Hawaii10, University of Georgia11, University of Victoria12, National Research Council13, Amherst College14, Stony Brook University15, Université de Montréal16, Johns Hopkins University17, Yale University18, Leiden University19, Lawrence Livermore National Laboratory20, University of Arizona21, University of Notre Dame22, University of Michigan23, University of Exeter24, University of California, San Diego25, Ames Research Center26, American Museum of Natural History27, Cornell University28
TL;DR: The results of a ~4 yr direct imaging survey of 104 stars to resolve and characterize circumstellar debris disks in scattered light as part of the Gemini Planet Imager (GPI) Exoplanet Survey were reported in this article.
Abstract: We report the results of a ~4 yr direct imaging survey of 104 stars to resolve and characterize circumstellar debris disks in scattered light as part of the Gemini Planet Imager (GPI) Exoplanet Survey We targeted nearby (≲150 pc), young (≲500 Myr) stars with high infrared (IR) excesses (L_(IR)/L★ > 10⁻⁵), including 38 with previously resolved disks Observations were made using the GPI high-contrast integral field spectrograph in H-band (16 μm) coronagraphic polarimetry mode to measure both polarized and total intensities We resolved 26 debris disks and 3 protoplanetary/transitional disks Seven debris disks were resolved in scattered light for the first time, including newly presented HD 117214 and HD 156623, and we quantified basic morphologies of five of them using radiative transfer models All of our detected debris disks except HD 156623 have dust-poor inner holes, and their scattered-light radii are generally larger than corresponding radii measured from resolved thermal emission and those inferred from spectral energy distributions To assess sensitivity, we report contrasts and consider causes of nondetections Detections were strongly correlated with high IR excess and high inclination, although polarimetry outperformed total intensity angular differential imaging for detecting low-inclination disks (≲70°) Based on postsurvey statistics, we improved upon our presurvey target prioritization metric predicting polarimetric disk detectability We also examined scattered-light disks in the contexts of gas, far-IR, and millimeter detections Comparing H-band and ALMA fluxes for two disks revealed tentative evidence for differing grain properties Finally, we found no preference for debris disks to be detected in scattered light if wide-separation substellar companions were present
TL;DR: The detection of helium in the extended atmosphere of the sub-Saturn WASP-107b using high resolution near-infrared spectra from Keck II/NIRSPEC was reported in this paper.
Abstract: We present the detection of helium in the extended atmosphere of the sub-Saturn WASP-107b using high resolution ($R \approx 25000$) near-infrared spectra from Keck II/NIRSPEC. We find peak excess absorption of $7.26 \pm 0.24\%$ (30$\sigma$) centered on the HeI triplet at 10833A. The amplitude and shape of the helium absorption profile is in excellent agreement with previous observations of escaping helium from this planet made by CARMENES and HST. This suggests there is no significant temporal variation in the signature of escaping helium from the planet over a two year baseline. This result demonstrates Keck II/NIRSPEC's ability to detect atmospheric escape in exoplanets, making it a useful instrument to further our understanding of the evaporation of exoplanetary atmospheres via ground-based observations of HeI.
TL;DR: In this paper, the authors analyzed the transmission and emission spectra of the ultra-hot Jupiter WASP-76 b, observed with the G141 grism of the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3).
Abstract: We analyze the transmission and emission spectra of the ultra-hot Jupiter WASP-76 b, observed with the G141 grism of the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3). We reduce and fit the raw data for each observation using the open-source software Iraclis before performing a fully Bayesian retrieval using the publicly available analysis suite TauREx 3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of titanium oxide (TiO) and vanadium oxide (VO) or non-gray clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyze this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, eliminating the need for a non-gray cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of TiO and an atmospheric thermal inversion, along with a significant amount of water. Given the brightness of the host star and the size of the atmospheric features, WASP-76 b is an excellent target for further characterization with HST, or with future facilities, to better understand the nature of its atmosphere, to confirm the presence of TiO and to search for other optical absorbers.
TL;DR: The Nancy Grace Roman Space Telescope (Roman) will perform a Galactic Exoplanet Survey (RGES) to discover bound exoplanets with semi-major axes greater than 1 au using gravitational microlensing as discussed by the authors.
Abstract: The Nancy Grace Roman Space Telescope (Roman) will perform a Galactic Exoplanet Survey (RGES) to discover bound exoplanets with semi-major axes greater than 1 au using gravitational microlensing. Roman will even be sensitive to planetary mass objects that are not gravitationally bound to any host star. Such free-floating planetary mass objects (FFPs) will be detected as isolated microlensing events with timescales shorter than a few days. A measurement of the abundance and mass function of FFPs is a powerful diagnostic of the formation and evolution of planetary systems, as well as the physics of the formation of isolated objects via direct collapse. We show that Roman will be sensitive to FFP lenses that have masses from that of Mars ($0.1 M_\oplus$) to gas giants ($M\gtrsim100M_\oplus$) as isolated lensing events with timescales from a few hours to several tens of days, respectively. We investigate the impact of the detection criteria on the survey, especially in the presence of finite-source effects for low-mass lenses. The number of detections will depend on the abundance of such FFPs as a function of mass, which is at present poorly constrained. Assuming that FFPs follow the fiducial mass function of cold, bound planets adapted from Cassan et al. (2012), we estimate that Roman will detect $\sim250$ FFPs with masses down to that of Mars (including $\sim 60$ with masses $\le M_\oplus$). We also predict that Roman will improve the upper limits on FFP populations by at least an order of magnitude compared to currently-existing constraints.
TL;DR: In this article, the atmospheric characterization of three large, gaseous planets: WASP-127 b, WASP79 b, and WASP62 b was performed using spectroscopic data obtained with the G141 grism (1.088 −1.68 μm).
Abstract: This paper presents the atmospheric characterization of three large, gaseous planets: WASP-127 b, WASP-79 b, and WASP-62 b. We analyzed spectroscopic data obtained with the G141 grism (1.088–1.68 μm) of the Wide Field Camera 3 on board the Hubble Space Telescope using the Iraclis pipeline and the TauREx3 retrieval code, both of which are publicly available
TL;DR: In this article, it was shown that axion minihalos in galaxy clusters should collectively produce subtle surface density fluctuations of amplitude with projected length scales of 10−4 and AU, which imprint irregularities in the microlensing light curves of caustic transiting stars.
Abstract: Axions are a viable candidate for Cold Dark Matter (CDM) which should generically form minihalos of sub-planetary masses from white-noise isocurvature density fluctuations if the Peccei-Quinn phase transition occurs after inflation. Despite being denser than the larger halos formed out of adiabatic fluctuations from inflation, axion minihalos have surface densities much smaller than the critical value required for gravitational lensing to produce multiple images or high magnification, and hence are practically undetectable as lenses in isolation. However, their lensing effect can be enhanced when superposed near critical curves of other lenses. We propose a method to detect them through photometric monitoring of recently discovered caustic transiting stars behind cluster lenses, under extreme magnification factors $\mu \gtrsim 10^3$--$10^4$ as the lensed stars cross microlensing caustics induced by intracluster stars. For masses of the first gravitationally collapsed minihalos in the range $\sim 10^{-15}$--$10^{-8}\,h^{-1}\,M_\odot$, we show that axion minihalos in galaxy clusters should collectively produce subtle surface density fluctuations of amplitude $\sim 10^{-4}$--$10^{-3}$ on projected length scales of $\sim 10$--$10^4\,$AU, which imprint irregularities in the microlensing light curves of caustic transiting stars. We estimate that, inside a cluster halo and over the age of the Universe, most of these minihalos are likely to avoid dynamic disruption by encounters with stars or other minihalos.
TL;DR: In this paper, a neural network called Auriga was developed to estimate the age, extinction, and distance of a stellar group based on the input photometry and parallaxes of individual members.
Abstract: We present the results of the hierarchical clustering analysis of the Gaia DR2 data to search for clusters, co-moving groups, and other stellar structures. The current paper builds on the sample from the previous work, extending it in distance from 1 kpc to 3 kpc, increasing the number of identified structures up to 8292. To aid in the analysis of the population properties, we developed a neural network called Auriga to robustly estimate the age, extinction, and distance of a stellar group based on the input photometry and parallaxes of the individual members. We apply Auriga to derive the properties of not only the structures found in this paper, but also previously identified open clusters. Through this work, we examine the temporal structure of the spiral arms. Specifically, we find that the Sagittarius arm has moved by >500 pc in the last 100 Myr, and the Perseus arm has been experiencing a relative lull in star formation activity over the last 25 Myr. We confirm the findings from the previous paper on the transient nature of the spiral arms, with the timescale of transition of a few 100 Myr. Finally, we find a peculiar ~1 Gyr old stream of stars that appears to be heliocentric. It is unclear what is the origin of it.
Smithsonian Institution1, Harvard University2, Catholic University of the Most Holy Conception3, University of Grenoble4, University of Cambridge5, Queen's University Belfast6, University of Geneva7, INAF8, American Association of Variable Star Observers9, University of Toronto10, Massachusetts Institute of Technology11, University of Kansas12, Princeton University13, Ames Research Center14, Search for extraterrestrial intelligence15, Goddard Space Flight Center16, University of Porto17, University of Padua18, European Southern Observatory19, Federal University of Rio Grande do Norte20, University of North Carolina at Chapel Hill21, Georgia State University22, University of Louisville23, Swarthmore College24, University of California, Santa Cruz25, University of California, Berkeley26, Université de Montréal27, National Scientific and Technical Research Council28, George Mason University29, University of St Andrews30, California Institute of Technology31, Technical University of Denmark32
TL;DR: The work in this paper is supported by a Dunlap Fellowship at the Dunlap Institute for Astronomy & Astrophysics, funded through an endowment established by the Dunllap family and the University of Toronto.
Abstract: Funding: N.A.D. acknowledges support from FONDECYT 3180063.A.M. acknowledges support from the senior Kavli InstituteFellowships.J.G.W. is supported by a grant from the John Templeton Foundation. .C.Z. is supported by a Dunlap Fellowship at the Dunlap Institute for Astronomy & Astrophysics, funded through an endowment established by the Dunlap family and the University of Toronto. I.J.M.C. acknowledges support from the NSF through grant AST-1824644 and NASA through Caltech/JPL grant RSA-1610091. F.L. gratefully acknowledges a scholarship from the Fondation Zdnek et Michaela Bakala. M.S. thanks the Swiss National Science Foundation (SNSF) and Geneva University for their continuous support of our exoplanet researches. This work has been in particular carried out in the frame of the National Center for Competence in Research “PlanetS” supported by SNSF.C.A.W. acknowledges support from Science and Technology Facilities Council grant ST/P000312/1. N.C.S. acknowledges supported by FCT, Fundacao para a Ciencia e a Tecnologia, through national funds and by FEDER through COMPETE2020, Programa Operacional Competitividade e Internacionalizacao, by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953. M.Pi. gratefully acknowledges support from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 313014 (ETAEARTH). J.R.M. acknowledges support by the CAPES, CNPq, and FAPERN Brazilian agencies.