- ID:
- ivo://CDS.VizieR/J/A+A/605/A72
- Title:
- Planetary systems AMD-stability
- Short Name:
- J/A+A/605/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here in full detail the evolution of the angular momentum deficit (AMD) during collisions as it was described in (Laskar 2000, Physical Review Letters, 84, 3240). Since then, the AMD has been revealed to be a key parameter for the understanding of the outcome of planetary formation models. We define here the AMD-stability criterion that can be easily verified on a newly discovered planetary system. We show how AMD-stability can be used to establish a classification of the multiplanet systems in order to exhibit the planetary systems that are long-term stable because they are AMD-stable, and those that are AMD- unstable which then require some additional dynamical studies to conclude on their stability. The AMD-stability classification is applied to the 131 multiplanet systems from The Extrasolar Planet Encyclopaedia database (exoplanet.eu) for which the orbital elements are sufficiently well known.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/226/7
- Title:
- Planet candidates discovered using K2's 1st yr
- Short Name:
- J/ApJS/226/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R_P_=2.3R_{Earth}_, P=8.6 days, Teff=5300K, and Kp=12.7mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4R_{Earth}_, Kp=9-13mag). Of particular interest are 76 planets smaller than 2R_{Earth}_, 15 orbiting stars brighter than Kp=11.5mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems-including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2R_{Earth}_) and larger for candidates with radii >8R_{Earth}_ and/or with P<3days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/155/21
- Title:
- Planet candidates from K2 campaigns 5-8
- Short Name:
- J/AJ/155/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 151 planet candidates orbiting 141 stars from K2 campaigns 5-8 (C5-C8), identified through a systematic search of K2 photometry. In addition, we identify 16 targets as likely eclipsing binaries, based on their light curve morphology. We obtained follow-up optical spectra of 105/141 candidate host stars and 8/16 eclipsing binaries to improve stellar properties and to identify spectroscopic binaries. Importantly, spectroscopy enables measurements of host star radii with ~10% precision, compared to ~40% precision when only broadband photometry is available. The improved stellar radii enable improved planet radii. Our curated catalog of planet candidates provides a starting point for future efforts to confirm and characterize K2 discoveries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/496/5423
- Title:
- 4 planet-hosting stars asteroseismic masses
- Short Name:
- J/MNRAS/496/5423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of planet occurrence as a function of stellar mass is important for a better understanding of planet formation. Estimating stellar mass, especially in the red giant regime, is difficult. In particular, stellar masses of a sample of evolved planet-hosting stars based on spectroscopy and grid-based modelling have been put to question over the past decade with claims they were overestimated. Although efforts have been made in the past to reconcile this dispute using asteroseismology, results were inconclusive. In an attempt to resolve this controversy, we study four more evolved planet-hosting stars in this paper using asteroseismology, and we revisit previous results to make an informed study of the whole ensemble in a self-consistent way. For the four new stars, we measure their masses by locating their characteristic oscillation frequency, numax, from their radial velocity time series observed by SONG. For two stars, we are also able to measure the large frequency separation, Delta nu, helped by extended SONG single-site and dual-site observations and new TESS observations. We establish the robustness of the numax-only-based results by determining the stellar mass from Delta nu, and from both Delta nu and numax. We then compare the seismic masses of the full ensemble of 16 stars with the spectroscopic masses from three different literature sources. We find an offset between the seismic and spectroscopic mass scales that is mass-dependent, suggesting that the previously claimed overestimation of spectroscopic masses only affects stars more massive than about 1.6M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/3961
- Title:
- Planet-hosting stars chemical compositions
- Short Name:
- J/MNRAS/495/3961
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a line-by-line differential analysis of a sample of 16 planet-hosting stars and 68 comparison stars using high-resolution, high signal-to-noise ratio spectra gathered using Keck. We obtained accurate stellar parameters and high-precision relative chemical abundances with average uncertainties in Teff, logg, [Fe/H], and [X/H] of 15K, 0.034cm/s^2^, 0.012dex, and 0.025dex, respectively. For each planet host, we identify a set of comparison stars and examine the abundance differences (corrected for Galactic chemical evolution effect) as a function of the dust condensation temperature, Tcond, of the individual elements. While we confirm that the Sun exhibits a negative trend between abundance and Tcond, we also confirm that the remaining planet hosts exhibit a variety of abundance-Tcond trends with no clear dependence upon age, metallicity, or Teff. The diversity in the chemical compositions of planet-hosting stars relative to their comparison stars could reflect the range of possible planet-induced effects present in these planet hosts, from the sequestration of rocky material (refractory poor) to the possible ingestion of planets (refractory rich). Other possible explanations include differences in the time-scale, efficiency and degree of planet formation, or inhomogeneous chemical evolution. Although we do not find an unambiguous chemical signature of planet formation among our sample, the high-precision chemical abundances of the host stars are essential for constraining the composition and structure of their exoplanets.
- ID:
- ivo://CDS.VizieR/J/AJ/152/187
- Title:
- Planet occurrence and stellar metallicity for KOIs
- Short Name:
- J/AJ/152/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Host star metallicity provides a measure of the conditions in protoplanetary disks at the time of planet formation. Using a sample of over 20000 Kepler stars with spectroscopic metallicities from the LAMOST survey, we explore how the exoplanet population depends on host star metallicity as a function of orbital period and planet size. We find that exoplanets with orbital periods less than 10 days are preferentially found around metal-rich stars ([Fe/H]{simeq}0.15+/-0.05dex). The occurrence rates of these hot exoplanets increases to ~30% for super-solar metallicity stars from ~10% for stars with a sub-solar metallicity. Cooler exoplanets, which reside at longer orbital periods and constitute the bulk of the exoplanet population with an occurrence rate of >~90%, have host star metallicities consistent with solar. At short orbital periods, P<10days, the difference in host star metallicity is largest for hot rocky planets (<1.7R_{Earth}_), where the metallicity difference is [Fe/H]{simeq}0.25+/-0.07dex. The excess of hot rocky planets around metal-rich stars implies they either share a formation mechanism with hot Jupiters, or trace a planet trap at the protoplanetary disk inner edge, which is metallicity dependent. We do not find statistically significant evidence for a previously identified trend that small planets toward the habitable zone are preferentially found around low-metallicity stars. Refuting or confirming this trend requires a larger sample of spectroscopic metallicities.
- ID:
- ivo://CDS.VizieR/J/ApJ/814/130
- Title:
- Planet occurrence rates calculated for KOIs
- Short Name:
- J/ApJ/814/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trends in the planet population with host star mass provide an avenue to constrain planet formation theories. We derive the planet radius distribution function for Kepler stars of different spectral types, sampling a range in host star masses. We find that M dwarf stars have 3.5 times more small planets (1.0-2.8R_{Earth}_) than main-sequence FGK stars, but two times fewer Neptune-sized and larger (>2.8R_{Earth}_) planets. We find no systematic trend in the planet size distribution between spectral types F, G, and K to explain the increasing occurrence rates. Taking into account the mass-radius relationship and heavy-element mass of observed exoplanets, and assuming those are independent of spectral type, we derive the inventory of the heavy-element mass locked up in exoplanets at short orbits. The overall higher planet occurrence rates around M stars are not consistent with the redistribution of the same mass into more, smaller planets. At the orbital periods and planet radii where Kepler observations are complete for all spectral types, the average heavy-element mass locked up in exoplanets increases roughly inversely with stellar mass from 4M_{Earth}_ in F stars to 5M_{Earth}_in G and K stars to 7M_{Earth}_ in M stars. This trend stands in stark contrast with observed protoplanetary disk masses that decrease toward lower mass stars, and provides a challenge for current planet formation models. Neither models of in situ formation nor migration of fully formed planets are consistent with these results. Instead, these results are indicative of large-scale inward migration of planetary building blocks --either through type-I migration or radial drift of dust grains-- that is more efficient for lower mass stars, but does not result in significantly larger or smaller planets.
- ID:
- ivo://CDS.VizieR/J/ApJS/216/7
- Title:
- Planets Around Low-Mass Stars (PALMS). IV.
- Short Name:
- J/ApJS/216/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a high-contrast adaptive optics imaging search for giant planets and brown dwarfs (>~1M_Jup_) around 122 newly identified nearby (<~40pc) young M dwarfs. Half of our targets are younger than 135Myr and 90% are younger than the Hyades (620Myr). After removing 44 close stellar binaries (implying a stellar companion fraction of >35.4%+/-4.3% within 100AU), 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 (0.1-0.6M_{sun}_) to date. Our H- and K-band coronagraphic observations with Keck/NIRC2 and Subaru/HiCIAO achieve typical contrasts of 12-14mag and 9-13mag at 1", respectively, which correspond to limiting planet masses of 0.5-10M_Jup_ at 5-33AU for 85% of our sample. We discovered four young brown dwarf companions: 1RXS J235133.3+312720B (32+/-6M_Jup_; L0^+2^_-1_; 120+/-20AU), GJ 3629B (64^+30^_-23_M_Jup_; M7.5+/-0.5; 6.5+/-0.5AU), 1RXS J034231.8+121622B (35+/-8M_Jup_; L0+/-1; 19.8+/-0.9AU), and 2MASS J15594729+4403595B (43+/-9M_Jup_; M8.0+/-0.5; 190+/-20AU). 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.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A45
- Title:
- Planets around metal-poor stars
- Short Name:
- J/A+A/543/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. We analyzed two samples of metal-poor stars (-2.0<[Fe/H]<0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. A general Lomb Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of 2.63^+2.5^_-0.89_%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent (4.48^+4.04^_-1.38_%) around stars with [Fe/H]>-0.7, while they are rare around stars with [Fe/H]<-0.7. We conclude that giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/146
- Title:
- Planets in Kepler's multi-transiting systems
- Short Name:
- J/ApJ/790/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the orbital architectures of Kepler systems having multiple-planet candidates identified in the analysis of data from the first six quarters of Kepler data and reported by Batalha et al. (2013, J/ApJS/204/24). These data show 899 transiting planet candidates in 365 multiple-planet systems and provide a powerful means to study the statistical properties of planetary systems. Using a generic mass-radius relationship, we find that only two pairs of planets in these candidate systems (out of 761 pairs total) appear to be on Hill-unstable orbits, indicating ~96% of the candidate planetary systems are correctly interpreted as true systems. We find that planet pairs show little statistical preference to be near mean-motion resonances. We identify an asymmetry in the distribution of period ratios near first-order resonances (e.g., 2:1, 3:2), with an excess of planet pairs lying wide of resonance and relatively few lying narrow of resonance. Finally, based upon the transit duration ratios of adjacent planets in each system, we find that the interior planet tends to have a smaller transit impact parameter than the exterior planet does. This finding suggests that the mode of the mutual inclinations of planetary orbital planes is in the range 1.{deg}0-2.{deg}2, for the packed systems of small planets probed by these observations.
