- ID:
- ivo://CDS.VizieR/J/ApJ/791/10
- Title:
- Radius distribution of planets around cool stars
- Short Name:
- J/ApJ/791/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We calculate an empirical, non-parametric estimate of the shape of the period-marginalized radius distribution of planets with periods less than 150 days using the small yet well-characterized sample of cool (T_eff_< 4000 K) dwarf stars in the Kepler catalog. In particular, we present and validate a new procedure, based on weighted kernel density estimation, to reconstruct the shape of the planet radius function down to radii smaller than the completeness limit of the survey at the longest periods. Under the assumption that the period distribution of planets does not change dramatically with planet radius, we show that the occurrence of planets around these stars continues to increase to below 1 R_{sun}_, and that there is no strong evidence for a turnover in the planet radius function. In fact, we demonstrate using many iterations of simulated data that a spurious turnover may be inferred from data even when the true distribution continues to rise toward smaller radii. Finally, the sharp rise in the radius distribution below ~3 R_{sun}_ implies that a large number of planets await discovery around cool dwarfs as the sensitivities of ground-based transit surveys increase.
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- ID:
- ivo://CDS.VizieR/J/ApJ/795/L14
- Title:
- Refracted light signals to discriminate exoplanets
- Short Name:
- J/ApJ/795/L14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a method to distinguish between cloudy, hazy, and clear sky (free of clouds and hazes) exoplanet atmospheres that could be applicable to upcoming large aperture space- and ground-based telescopes such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). These facilities will be powerful tools for characterizing transiting exoplanets, but only after a considerable amount of telescope time is devoted to a single planet. A technique that could provide a relatively rapid means of identifying haze-free targets (which may be more valuable targets for characterization) could potentially increase the science return for these telescopes. Our proposed method utilizes broadband observations of refracted light in the out-of-transit spectrum. Light refracted through an exoplanet atmosphere can lead to an increase of flux prior to ingress and subsequent to egress. Because this light is transmitted at pressures greater than those for typical cloud and haze layers, the detection of refracted light could indicate a cloud- or haze-free atmosphere. A detection of refracted light could be accomplished in <10 hr for Jovian exoplanets with JWST and <5 hr for super-Earths/mini-Neptunes with E-ELT. We find that this technique is most effective for planets with equilibrium temperatures between 200 and 500 K, which may include potentially habitable planets. A detection of refracted light for a potentially habitable planet would strongly suggest the planet was free of a global cloud or haze layer, and therefore a promising candidate for follow-up observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/159
- Title:
- Relative Ic photometry of WASP-17
- Short Name:
- J/ApJ/709/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day orbit around a sub-solar metallicity, V=11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a retrograde orbit ({lambda}~-150{deg}), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric orbit, such as the highly eccentric orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
- ID:
- ivo://CDS.VizieR/J/ApJ/692/L100
- Title:
- Relative photometry of WASP-10
- Short Name:
- J/ApJ/692/L100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the photometry of WASP-10 during a transit of its short-period Jovian planet. We employed the novel point-spread function shaping capabilities of the Orthogonal Parallel Transfer Imaging Camera mounted on the UH 2.2m telescope to achieve a photometric precision of 4.7x10^-4^ per 1.3 minute sample. With this new light curve, in conjunction with stellar evolutionary models, we improve on existing measurements of the planetary, stellar, and orbital parameters. We find a stellar radius R_*_=0.698+/-0.012R_{sun}_ and a planetary radius R_P_=1.080+/-0.020R_Jup_. The quoted errors do not include any possible systematic errors in the stellar evolutionary models. Our measurement improves the precision of the planet's radius by a factor of 4, and revises the previous estimate downward by 16% (2.5{sigma}, where {sigma} is the quadrature sum of the respective confidence limits). Our measured radius of WASP-10b is consistent with previously published theoretical radii for irradiated Jovian planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/715/421
- Title:
- Relative photometry of WASP-3
- Short Name:
- J/ApJ/715/421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3. Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis, {lambda}=3.3^+2.5^_-4.4_deg. This alignment between the axes suggests that WASP-3b has a low orbital inclination relative to the equatorial plane of its parent star. During our first night of spectroscopic measurements, we observed an unexpected redshift briefly exceeding the expected sum of the orbital and RM velocities by 140m/s. This anomaly could represent the occultation of material erupting from the stellar photosphere, although it is more likely to be an artifact caused by moonlight scattered into the spectrograph.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/302
- Title:
- Relative photometry of XO-3
- Short Name:
- J/ApJ/700/302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric and spectroscopic observations of the 2009 February 2 transit of the exoplanet XO-3b. The new data show that the planetary orbital axis and stellar rotation axis are misaligned, as reported earlier by Hebrard and coworkers. We find the angle between the sky projections of the two axes to be 37.3+/-3.7deg, as compared to the previously reported value of 70+/-15deg. The significance of this discrepancy is unclear because there are indications of systematic effects. XO-3b is the first exoplanet known to have a highly inclined orbit relative to the equatorial plane of its parent star, and as such it may fulfill the predictions of some scenarios for the migration of massive planets into close-in orbits. We revisit the statistical analysis of spin-orbit alignment in hot-Jupiter systems. Assuming the stellar obliquities to be drawn from a single Rayleigh distribution, we find the mode of the distribution to be 13^+5^_-2_deg. However, it remains the case that a model representing two different migration channels-in which some planets are drawn from a perfectly aligned distribution and the rest are drawn from an isotropic distribution-is favored over a single Rayleigh distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A76
- Title:
- Relative radial velocities and K2 fluxes of K2-132
- Short Name:
- J/A+A/613/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P<~10-days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017AJ....154..254G). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff=4878+/-70K, logg=3.289+/-0.004, and [Fe/H]=-0.11+/-0.05dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P=9.1708+/-0.0025d, e=0.290+/-0.049, Mp=0.495+/-0.007M_J_ and Rp=1.089+/-0.006R_J_. This is the fifth known planet orbiting any giant star with a<0.1, and the most eccentric one among them, making K2-132 b a very interesting object.
- ID:
- ivo://CDS.VizieR/J/AJ/141/63
- Title:
- Relative radial velocities of HAT-P-4 and HAT-P-14
- Short Name:
- J/AJ/141/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of the Rossiter-McLaughlin effect for two exoplanetary systems, revealing the orientations of their orbits relative to the rotation axes of their parent stars. HAT-P-4b is prograde, with a sky-projected spin-orbit angle of {lambda}=-4.9+/-11.9{deg}. In contrast, HAT-P-14b is retrograde, with {lambda}=189.1+/-5.1{deg}. These results conform with a previously noted pattern among the stellar hosts of close-in giant planets: hotter stars have a wide range of obliquities and cooler stars have low obliquities. This, in turn, suggests that three-body dynamics and tidal dissipation are responsible for the short-period orbits of many exoplanets. In addition, our data revealed a third body in the HAT-P-4 system, which could be a second planet or a companion star.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A34
- Title:
- Resolved astrometry of ten O-type binaries
- Short Name:
- J/A+A/601/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our long-term aim is to derive model-independent stellar masses and distances for long period massive binaries by combining apparent astrometric orbit with double-lined radial velocity amplitudes (SB2).We followed-up ten O+O binaries with AMBER, PIONIER and GRAVITY at the VLTI. Here, we report on 130 astrometric observations over the last seven years. We combined this dataset with distance estimates to compute the total mass of the systems. We also computed preliminary individual component masses for the five systems with available SB2 radial velocities. Nine of the ten binaries have their three-dimensional orbit well constrained. Four of them are known to be colliding wind, non-thermal radio emitters, and thus constitute valuable targets for future high angular resolution radio imaging. Two binaries break the correlation between period and eccentricity tentatively observed in previous studies. This suggests either that massive star formation produces a wide range of systems, or that several binary formation mechanisms are at play. Finally, we found that the use of existing SB2 radial velocity amplitudes can lead to unrealistic masses and distances.If not understood, the biases in radial velocity amplitudes will represent an intrinsic limitation for estimating dynamical masses from SB2+interferometry or SB2+Gaia. Nevertheless, our results can be combined with future Gaia astrometry to measure the dynamical masses and distances of the individual components with an accuracy of 5 to 15%, completely independently of the radial velocities.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/99
- Title:
- Revised radii of KIC stars & planets using Gaia DR2
- Short Name:
- J/ApJ/866/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One bottleneck for the exploitation of data from the Kepler mission for stellar astrophysics and exoplanet research has been the lack of precise radii and evolutionary states for most of the observed stars. We report revised radii of 177911 Kepler stars derived by combining parallaxes from the Gaia Data Release 2 with the DR25 Kepler Stellar Properties Catalog. The median radius precision is ~8%, a typical improvement by a factor of 4-5 over previous estimates for typical Kepler stars. We find that ~67% (~120000) of all Kepler targets are main-sequence stars, ~21% (~37000) are subgiants, and ~12% (~21000) are red giants, demonstrating that subgiant contamination is less severe than some previous estimates and that Kepler targets are mostly main-sequence stars. Using the revised stellar radii, we recalculate the radii for 2123 confirmed and 1922 candidate exoplanets. We confirm the presence of a gap in the radius distribution of small, close-in planets, but find that the gap is mostly limited to incident fluxes >200F_{Earth}_, and its location may be at a slightly larger radius (closer to ~2R_{Earth}_) when compared to previous results. Furthermore, we find several confirmed exoplanets occupying a previously described "hot super-Earth desert" at high irradiance, show the relation between a gas-giant planet's radius and its incident flux, and establish a bona fide sample of eight confirmed planets and 30 planet candidates with Rp<2R_{Earth}_ in circumstellar "habitable zones" (incident fluxes between 0.25 and 1.50F_{Earth}_). The results presented here demonstrate the potential for transformative characterization of stellar and exoplanet populations using Gaia data.
