- ID:
- ivo://CDS.VizieR/J/AJ/154/109
- Title:
- California-Kepler Survey (CKS). III. Planet radii
- Short Name:
- J/AJ/154/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey to study the size distribution of 2025 Kepler planets in fine detail. We detect a factor of >=2 deficit in the occurrence rate distribution at 1.5-2.0R_{Earth}_. This gap splits the population of close-in (P<100days) small planets into two size regimes: R_P_<1.5R_{Earth}_ and R_P_=2.0--3.0R_{Earth}_, with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0R_{Earth}_ supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5R_{Earth}_ or smaller with varying amounts of low-density gas that determine their total sizes.
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- ID:
- ivo://CDS.VizieR/J/AJ/154/108
- Title:
- California-Kepler Survey (CKS). II. Properties
- Short Name:
- J/AJ/154/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar and planetary properties for 1305 Kepler Objects of Interest hosting 2025 planet candidates observed as part of the California-Kepler Survey. We combine spectroscopic constraints, presented in Paper I, with stellar interior modeling to estimate stellar masses, radii, and ages. Stellar radii are typically constrained to 11%, compared to 40% when only photometric constraints are used. Stellar masses are constrained to 4%, and ages are constrained to 30%. We verify the integrity of the stellar parameters through comparisons with asteroseismic studies and Gaia parallaxes. We also recompute planetary radii for 2025 planet candidates. Because knowledge of planetary radii is often limited by uncertainties in stellar size, we improve the uncertainties in planet radii from typically 42% to 12%. We also leverage improved knowledge of stellar effective temperature to recompute incident stellar fluxes for the planets, now precise to 21%, compared to a factor of two when derived from photometry.
- ID:
- ivo://CDS.VizieR/J/AJ/154/107
- Title:
- California-Kepler Survey (CKS). I. 1305 stars
- Short Name:
- J/AJ/154/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The California-Kepler Survey (CKS) is an observational program developed to improve our knowledge of the properties of stars found to host transiting planets by NASA's Kepler Mission. The improvement stems from new high-resolution optical spectra obtained using HIRES at the W. M. Keck Observatory. The CKS stellar sample comprises 1305 stars classified as Kepler objects of interest, hosting a total of 2075 transiting planets. The primary sample is magnitude-limited (K_p_<14.2) and contains 960 stars with 1385 planets. The sample was extended to include some fainter stars that host multiple planets, ultra-short period planets, or habitable zone planets. The spectroscopic parameters were determined with two different codes, one based on template matching and the other on direct spectral synthesis using radiative transfer. We demonstrate a precision of 60K in T_eff_, 0.10dex in logg, 0.04dex in [Fe/H], and 1.0km/s in Vsini. In this paper, we describe the CKS project and present a uniform catalog of spectroscopic parameters. Subsequent papers in this series present catalogs of derived stellar properties such as mass, radius, and age; revised planet properties; and statistical explorations of the ensemble. CKS is the largest survey to determine the properties of Kepler stars using a uniform set of high-resolution, high signal-to-noise ratio spectra. The HIRES spectra are available to the community for independent analyses.
- ID:
- ivo://CDS.VizieR/J/AJ/155/89
- Title:
- California-Kepler Survey (CKS). IV. Planets
- Short Name:
- J/AJ/155/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Probing the connection between a star's metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity M. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having P=10-100 days and R_P_=1.0-1.7 R_{Earth}_, planet occurrence is nearly constant over metallicities spanning -0.4 to +0.4 dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes (R_P_=1.7-4.0 R_{Earth}_) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as df{prop.to}10^{beta}M^dM, where {beta} characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. For warm super-Earths {beta}=-0.3_-0.2_^+0.2^, while for hot Jupiters {beta}=+3.4_-0.8_^+0.9^. High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7 R_{Earth}_. The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet-planet scattering.
- ID:
- ivo://CDS.VizieR/J/AJ/155/48
- Title:
- California-Kepler Survey (CKS). V. Masses and radii
- Short Name:
- J/AJ/155/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have established precise planet radii, semimajor axes, incident stellar fluxes, and stellar masses for 909 planets in 355 multi-planet systems discovered by Kepler. In this sample, we find that planets within a single multi-planet system have correlated sizes: each planet is more likely to be the size of its neighbor than a size drawn at random from the distribution of observed planet sizes. In systems with three or more planets, the planets tend to have a regular spacing: the orbital period ratios of adjacent pairs of planets are correlated. Furthermore, the orbital period ratios are smaller in systems with smaller planets, suggesting that the patterns in planet sizes and spacing are linked through formation and/or subsequent orbital dynamics. Yet, we find that essentially no planets have orbital period ratios smaller than 1.2, regardless of planet size. Using empirical mass-radius relationships, we estimate the mutual Hill separations of planet pairs. We find that 93% of the planet pairs are at least 10 mutual Hill radii apart, and that a spacing of ~20 mutual Hill radii is most common. We also find that when comparing planet sizes, the outer planet is larger in 65%+/-0.4% of cases, and the typical ratio of the outer to inner planet size is positively correlated with the temperature difference between the planets. This could be the result of photo-evaporation.
- ID:
- ivo://CDS.VizieR/J/AJ/156/264
- Title:
- California-Kepler Survey. VII. Planet radius gap
- Short Name:
- J/AJ/156/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of planet sizes encodes details of planet formation and evolution. We present the most precise planet size distribution to date based on Gaia parallaxes, Kepler photometry, and spectroscopic temperatures from the California-Kepler Survey. Previously, we measured stellar radii to 11% precision using high-resolution spectroscopy; by adding Gaia astrometry, the errors are now 3%. Planet radius measurements are, in turn, improved to 5% precision. With a catalog of ~1000 planets with precise properties, we probed in fine detail the gap in the planet size distribution that separates two classes of small planets, rocky super-Earths and gas-dominated sub-Neptunes. Our previous study and others suggested that the gap may be observationally under-resolved and inherently flat-bottomed, with a band of forbidden planet sizes. Analysis based on our new catalog refutes this; the gap is partially filled in. Two other important factors that sculpt the distribution are a planet's orbital distance and its host-star mass, both of which are related to a planet's X-ray/UV irradiation history. For lower-mass stars, the bimodal planet distribution shifts to smaller sizes, consistent with smaller stars producing smaller planet cores. Details of the size distribution including the extent of the "sub-Neptune desert" and the width and slope of the gap support the view that photoevaporation of low-density atmospheres is the dominant evolutionary determinant of the planet size distribution.
- ID:
- ivo://CDS.VizieR/J/AJ/156/254
- Title:
- California-Kepler Survey.VI. Kepler multis & singles
- Short Name:
- J/AJ/156/254
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The California-Kepler Survey (CKS) catalog contains precise stellar and planetary properties for the Kepler planet candidates, including systems with multiple detected transiting planets ("multis") and systems with just one detected transiting planet ("singles", although additional planets could exist). We compared the stellar and planetary properties of the multis and singles in a homogeneous subset of the full CKS-Gaia catalog. We found that sub-Neptune-sized singles and multis do not differ in their stellar properties or planet radii. In particular: (1) The distributions of stellar properties M_*_, [Fe/H], and vsini for the Kepler sub-Neptune-sized singles and multis are statistically indistinguishable. (2) The radius distributions of the sub-Neptune-sized singles and multis with P>3 days are indistinguishable, and both have a valley at ~1.8 R_{Earth}_. However, there are significantly more detected short-period (P<3 days), sub-Neptune-sized singles than multis. The similarity of the host-star properties, planet radii, and radius valley for singles and multis suggests a common origin. The similar radius valley, which is likely sculpted by photo-evaporation from the host star within the first 100 Myr, suggests that planets in both singles and multis spend much of the first 100 Myr near their present, close-in locations. One explanation that is consistent with the similar fundamental properties of singles and multis is that many of the singles are members of multi-planet systems that underwent planet-planet scattering.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A76
- Title:
- California molecular cloud CO datacubes
- Short Name:
- J/A+A/642/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dense molecular filaments are central to the star formation process, but the detailed manner in which they fragment into prestellar cores is not well understood yet. Here, we investigate the fragmentation properties and dynamical state of several star-forming filaments in the X-shaped nebula region of the California molecular cloud in an effort to shed some light on this issue. We used multiwavelength far-infrared images from Herschel as well as the getsources and getfilaments extraction methods to identify dense cores and filaments in the region and derive their basic properties. We also used a map of ^13^CO(2-1) emission from the Arizona 10m Submillimeter Telescope (SMT) to constrain the dynamical state of the filaments. We identified ten filaments with aspect ratios of AR>4 and column density contrasts of C>0.5, as well as 57 dense cores, including two protostellar cores, 20 robust prestellar cores, 11 candidate prestellar cores, and 24 unbound starless cores. All ten filaments have roughly the same deconvolved full width at half maximum (FWHM), with a median value of 0.12+/-0.03pc, which is independent of their column densities ranging from <10^21^cm^-2^ to >10^22^cm^-2^. Two star-forming filaments (# 8 and # 10) stand out since they harbor quasi-periodic chains of dense cores with a typical projected core spacing of ~0.15pc. These two filaments have thermally supercritical line masses and are not static. Filament 8 exhibits a prominent transverse velocity gradient, suggesting that it is accreting gas from the parent cloud gas reservoir at an estimated rate of ~40+/-10M_{sun}_/Myr/pc. Filament 10 includes two embedded protostars with outflows and it is likely at a somewhat later evolutionary stage than filament 8. In both cases, the observed (projected) core spacing is similar to the filament width and significantly shorter than the canonical separation of ~4 times the filament width predicted by classical cylinder fragmentation theory. It is unlikely that projection effects can explain this discrepancy. We suggest that the continuous accretion of gas onto the two star-forming filaments, as well as the geometrical bending of the filaments, may account for the observed core spacing. Our findings suggest that the characteristic fragmentation lengthscale of molecular filaments is quite sensitive to external perturbations from the parent cloud, such as the gravitational accretion of ambient material.
- ID:
- ivo://CDS.VizieR/J/AJ/157/229
- Title:
- CALSPEC: WFC3 infrared grism spectrophotometry
- Short Name:
- J/AJ/157/229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The collections of spectral energy distributions (SEDs) in the Hubble Space Telescope (HST) CALSPEC database are augmented by 19 infrared (IR) SEDs from Wide Field Camera 3 (WFC3) IR grism spectra. Together, the two IR grisms, G102 and G141, cover the 0.8-1.7 {mu}m range with resolutions of R=200 and 150, respectively. These new WFC3 SEDs overlap existing CALSPEC Space Telescope Imaging Spectrograph (STIS) standard star flux distributions at 0.8-1 {mu}m with agreement to ~<1%. Some CALSPEC standards already have near-IR camera and multi-object spectrogragh (NICMOS) SEDs; but in their overlap region at 0.8-1.7 {mu}m, the WFC3 data have better wavelength accuracy, better spectral resolution, better repeatability, and, consequently, better flux distributions of ~1% accuracy in our CALSPEC absolute flux SEDs versus ~2% for NICMOS. With the improved SEDs in the WFC3 range, the modeled extrapolations to 32 {mu}m for the James Webb Space Telescope flux standards begin to lose precision longward of the 1.7 {mu}m WFC3 limit, instead of at the 1.0-{mu}m-long wavelength limit for STIS. For example, the extrapolated IR flux longward of 1.7 {mu}m for 1808347 increases by ~1% for the model fit to the data with WFC3, instead of just to the STIS SED alone.
- ID:
- ivo://CDS.VizieR/J/AJ/120/2190
- Title:
- Caltech Faint Galaxy Redshift Survey. XIV
- Short Name:
- J/AJ/120/2190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Morphological classifications are reported for Hubble Space Telescope images of 241 galaxies in the Hubble Deep Field and its flanking fields with measured redshifts in the interval 0.25<z<1.2, drawn from a magnitude-limited redshift survey to R=24.0. The galaxies are divided into three groups with redshifts in the intervals 0.25-0.6, 0.6-0.8, and 0.8-1.2. R_606_ images from the first group and I814 images from the second and third groups are compared with B-band images of nearby galaxies. All classifications were therefore made at approximately the same rest wavelength. Selection biases are discussed.
