- ID:
- ivo://CDS.VizieR/J/ApJ/750/L37
- Title:
- Stellar parameters of low-mass KOIs
- Short Name:
- J/ApJ/750/L37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report stellar parameters for late-K and M-type planet-candidate host stars announced by the Kepler Mission. We obtained medium-resolution, K-band spectra of 84 cool (T_eff_<~4400K) Kepler Objects of Interest (KOIs) from Borucki et al (2011, Cat. J/ApJ/728/117). We identified one object as a giant (KOI 977); for the remaining dwarfs, we measured effective temperatures (T_eff_) and metallicities [M/H] using the K-band spectral indices of Rojas-Ayala et al (2012, Cat. J/ApJ/748/93). We determine the masses (M_*_) and radii (R_*_) of the cool KOIs by interpolation onto the Dartmouth evolutionary isochrones. The resultant stellar radii are significantly less than the values reported in the Kepler Input Catalog and, by construction, correlate better with T_eff_. Applying the published KOI transit parameters to our stellar radius measurements, we report new physical radii for the planet candidates. Recalculating the equilibrium temperatures of the planet-candidates assuming Earth's albedo and re-radiation fraction, we find that three of the planet-candidates are terrestrial sized with orbital semimajor axes that lie within the habitable zones of their host stars (KOI 463.01, KOI 812.03, and KOI 854.01).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/158/56
- Title:
- Stellar parameters of M and K dwarfs
- Short Name:
- J/AJ/158/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Empirical correlations between stellar parameters such as rotation or radius and magnetic activity diagnostics require estimates of the effective temperatures and the stellar radii. The aim of this study is to propose simple methods that can be applied to large samples of stars in order to derive estimates of the stellar parameters. Good empirical correlations between red/infrared colors (e.g., (R-I)_C_) and effective temperatures have been well established for a long time. The more recent (R-I)_C_ color-T_eff_ correlation using the data of Mann et al. (2015, J/ApJ/804/64, hereafter M15) and Boyajian et al. (2012, J/ApJ/757/112, hereafter B12) shows that this color can be applied as a temperature estimate for large samples of stars. We find that the mean scatter in T_eff_ relative to the (R-I)_C_-T_eff_ relationship of B12 and M15 data is only +/-3{sigma}=44.6 K for K dwarfs and +/-3{sigma}=39.4 K for M dwarfs. These figures are small and show that the (R-I)_C_ color can be used as a first-guess effective temperature estimator for K and M dwarfs. We derive effective temperatures for about 1910 K and M dwarfs using the calibration of (R-I)_C_ color-T_eff_ from B12 and M15 data. We also compiled T_eff_ and metallicity measurements available in the literature using the VizieR database. We determine T_eff_ for 441 stars with previously unknown effective temperatures. We also identified 21 new spectroscopic binaries and one triple system from our high-resolution spectra.
- ID:
- ivo://CDS.VizieR/J/ApJS/168/297
- Title:
- Stellar parameters of nearby cool stars
- Short Name:
- J/ApJS/168/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive detailed theoretical models for 1074 nearby stars from the SPOCS (Spectroscopic Properties of Cool Stars) Catalog. We provide a catalog of physical parameters for 1074 stars that are based on a uniform set of high-quality spectral observations, a uniform spectral reduction procedure, and a uniform set of stellar evolutionary models.
- ID:
- ivo://CDS.VizieR/J/AJ/156/217
- Title:
- Stellar properties for M dwarfs in MEarth-South
- Short Name:
- J/AJ/156/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar rotation periods are valuable both for constraining models of angular momentum loss and for understanding how magnetic features impact inferences of exoplanet parameters. Building on our previous work in the northern hemisphere, we have used long-term, ground-based photometric monitoring from the MEarth Observatory to measure 234 rotation periods for nearby, southern hemisphere M dwarfs. Notable examples include the exoplanet hosts GJ 1132, LHS 1140, and Proxima Centauri. We find excellent agreement between our data and K2 photometry for the overlapping subset. Among the sample of stars with the highest quality data sets, we recover periods in 66%; as the length of the data set increases, our recovery rate approaches 100%. The longest rotation periods we detect are around 140 days, which we suggest represent the periods that are reached when M dwarfs are as old as the local thick disk (about 9 Gyr).
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/5487
- Title:
- Stellar properties of KIC stars
- Short Name:
- J/MNRAS/475/5487
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Investigations of the origin and evolution of the Milky Way disc have long relied on chemical and kinematic identifications of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined to the solar neighbourhood. Here, we break this impasse with the help of asteroseismic inference and perform a chronology of the evolution of the disc throughout the age of the Galaxy. We chemically dissect the Milky Way disc population using a sample of red giant stars spanning out to 2 kpc in the solar annulus observed by the Kepler satellite, with the added dimension of asteroseismic ages. Our results reveal a clear difference in age between the low- and high-{alpha} populations, which also show distinct velocity dispersions in the V and W components. We find no tight correlation between age and metallicity nor [{alpha}/Fe] for the high-{alpha} disc stars. Our results indicate that this component formed over a period of more than 2 Gyr with a wide range of [M/H] and [{alpha}/Fe] independent of time. Our findings show that the kinematic properties of young {alpha}-rich stars are consistent with the rest of the high-{alpha} population and different from the low-{alpha} stars of similar age, rendering support to their origin being old stars that went through a mass transfer or stellar merger event, making them appear younger, instead of migration of truly young stars formed close to the Galactic bar.
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/816
- Title:
- SuperWASP-North extrasolar planet candidates
- Short Name:
- J/MNRAS/379/816
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SuperWASP-I (Wide Angle Search for Planets-I) instrument observed 6.7 million stars between 8 and 15mag from La Palma during the 2004 May-September season. Our transit-hunting algorithm selected 11626 objects from the 184442 stars within the RA (right ascension) range 18-21h. We describe our thorough selection procedure whereby catalogue information is exploited along with careful study of the SuperWASP data to filter out, as far as possible, transit mimics. We have identified 35 candidates which we recommend for follow-up observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/647
- Title:
- SuperWASP-North extrasolar planet candidates
- Short Name:
- J/MNRAS/379/647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed photometric observations of nearly seven million stars with 8<V<15 with the SuperWASP-North instrument from La Palma between 2004 May to September. Fields in the right ascension range 17-18h, yielding over 185000 stars with sufficient quality data, have been searched for transits using a modified box least-squares (BLS) algorithm. We find a total of 58 initial transiting candidates which have high signal-to-noise ratio in the BLS, show multiple transit-like dips and have passed visual inspection. Analysis of the blending and the inferred planetary radii for these candidates leave, a total of seven transiting planet candidates which pass all the tests plus four which pass the majority. We discuss the derived parameters for these candidates and their properties and comment on the implications for future transit searches.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/1097
- Title:
- SuperWASP-North extrasolar planet candidates
- Short Name:
- J/MNRAS/384/1097
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Wide Angle Search for Planets (WASP) survey currently operates two installations, designated SuperWASP-N and SuperWASP-S, located in the Northern and Southern hemispheres, respectively. These installations are designed to provide high time-resolution photometry for the purpose of detecting transiting extrasolar planets, asteroids, and transient events. Here, we present results from a transit-hunting observing campaign using SuperWASP-N covering a right ascension (RA) range of 06h<RA<16h. This paper represents the fifth and final in the series of transit candidates released from the 2004 observing season. In total, 729335 stars from 33 fields were monitored with 130566 having sufficient precision to be scanned for transit signatures. Using a robust transit detection algorithm and selection criteria, six stars were found to have events consistent with the signature of a transiting extrasolar planet based on the photometry, including the known transiting planet XO-1b. These transit candidates are presented here along with discussion of follow-up observations and the expected number of candidates in relation to the overall observing strategy.
- ID:
- ivo://CDS.VizieR/J/AJ/161/134
- Title:
- Survey of stellar & planetary comp. within 25pc
- Short Name:
- J/AJ/161/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25pc. Using adaptive optics imaging observations from the Lick 3m and Palomar 200" Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single and multiple-star systems. We found that planets with masses in the range of 0.1-10M_J_ and with semimajor axes of 0.1-10au have an occurrence rate of 0.18_-0.03_^+0.04^ planets per star when they orbit single stars and an occurrence rate of 0.12{+/-}0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation <100au, and none had a separation <50au. These numbers yielded planet occurrence rates of 0.20_-0.06_^+0.07^ planets per star for binaries with separation aB>100au and 0.04_-0.02_^+0.04^ planets per star for binaries with separation aB<100au. The similarity in the planet occurrence rate around single stars and wide primaries implies that wide binary systems should actually host more planets than single-star systems, since they have more potential host stars. We estimated a system-wide planet occurrence rate of 0.3 planets per wide binary system for binaries with separations aB>100au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1au than inside 1au by nearly 4{sigma}, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100au.
- ID:
- ivo://CDS.VizieR/J/AJ/155/54
- Title:
- TBOSS Survey. II. ALMA continuum observations
- Short Name:
- J/AJ/155/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 885 {mu}m ALMA continuum flux densities for 24 Taurus members spanning the stellar/substellar boundary with spectral types from M4 to M7.75. Of the 24 systems, 22 are detected at levels ranging from 1.0 to 55.7 mJy. The two nondetections are transition disks, though other transition disks in the sample are detected. Converting ALMA continuum measurements to masses using standard scaling laws and radiative transfer modeling yields dust mass estimates ranging from ~0.3 to 20 M_{Earth}_. The dust mass shows a declining trend with central object mass when combined with results from submillimeter surveys of more massive Taurus members. The substellar disks appear as part of a continuous sequence and not a distinct population. Compared to older Upper Sco members with similar masses across the substellar limit, the Taurus disks are brighter and more massive. Both Taurus and Upper Sco populations are consistent with an approximately linear relationship in M_dust_ to M_star_, although derived power-law slopes depend strongly upon choices of stellar evolutionary model and dust temperature relation. The median disk around early-M stars in Taurus contains a comparable amount of mass in small solids as the average amount of heavy elements in Kepler planetary systems on short-period orbits around M-dwarf stars, with an order of magnitude spread in disk dust mass about the median value. Assuming a gas-to-dust ratio of 100:1, only a small number of low-mass stars and brown dwarfs have a total disk mass amenable to giant planet formation, consistent with the low frequency of giant planets orbiting M dwarfs.
