- ID:
- ivo://CDS.VizieR/J/ApJ/721/1
- Title:
- Keck ESI observations of Ly{alpha} systems
- Short Name:
- J/ApJ/721/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from a survey of SDSS quasars selected for strong HI damped Ly{alpha} (DLA) absorption with corresponding low equivalent width absorption from strong low-ion transitions (e.g., CII{lambda}1334 and SiII{lambda}1260). These metal-poor DLA candidates were selected from the SDSS fifth release quasar spectroscopic database, and comprise a large new sample for probing low-metallicity galaxies. Medium-resolution echellette spectra from the Keck Echellette Spectrograph and Imager spectrograph for an initial sample of 35 systems were obtained to explore the metal-poor tail of the DLA distribution and to investigate the nucleosynthetic patterns at these metallicities. We have estimated saturation corrections for the moderately underresolved spectra, and systems with very narrow Doppler parameters (b<=5km/s) will likely have underestimated abundances. For those systems with Doppler parameters b>5km/s, we have measured low-metallicity DLA gas with [X/H]<-2.4 for at least one of C, O, Si, or Fe. Assuming non-saturated components, we estimate that several DLA systems have [X/H]<-2.8, including five DLA systems with both low equivalent widths and low metallicity in transitions of both CII and OI. All of the measured DLA metallicities, however, exceed or are consistent with a metallicity of at least 1/1000 of solar, regardless of the effects of saturation in our spectra.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/860/109
- Title:
- Keck HIRES obs. of 245 subgiants (retired A stars)
- Short Name:
- J/ApJ/860/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]) but also on the mass (M*). However, measuring accurate masses for subgiants and giants is far more challenging than it is for their main-sequence counterparts, which has led to recent concerns regarding the veracity of the correlation between stellar mass and planet occurrence. In order to address these concerns, we use HIRES spectra to perform a spectroscopic analysis on a sample of 245 subgiants and derive new atmospheric and physical parameters. We also calculate the space velocities of this sample in a homogeneous manner for the first time. When reddening corrections are considered in the calculations of stellar masses and a -0.12M_{sun}_ offset is applied to the results, the masses of the subgiants are consistent with their space velocity distributions, contrary to claims in the literature. Similarly, our measurements of their rotational velocities provide additional confirmation that the masses of subgiants with M*>=1.6M_{sun}_ (the "retired A stars") have not been overestimated in previous analyses. Using these new results for our sample of evolved stars, together with an updated sample of FGKM dwarfs, we confirm that giant planet occurrence increases with both stellar mass and metallicity up to 2.0M_{sun}_. We show that the probability of formation of a giant planet is approximately a one-to-one function of the total amount of metals in the protoplanetary disk M* 10^[Fe/H]. This correlation provides additional support for the core accretion mechanism of planet formation.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A17
- Title:
- Keck+HIRES spectra of HD 80606 and HD 80607
- Short Name:
- J/A+A/582/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the probable chemical signature of planet formation in the remarkable binary system HD 80606/7. The star HD 80606 hosts a giant planet with 4 MJup detected by both transit and radial velocity techniques. We study condensation temperature Tc trends of volatile and refractory element abundances to determine whether there is a depletion of refractories that could be related to the terrestrial planet formation. Finally, we speculate about a possible planet around the star HD 80607.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/2
- Title:
- K2 EPIC stellar properties for 138600 targets
- Short Name:
- J/ApJS/224/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission uses the Kepler spacecraft to obtain high-precision photometry over ~80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission. We describe the construction of the EPIC, as well as modifications and shortcomings of the catalog. Kepler magnitudes (Kp) are shown to be accurate to ~0.1mag for the Kepler field, and the EPIC is typically complete to Kp~17 (Kp~19 for campaigns covered by Sloan Digital Sky Survey). We furthermore classify 138600 targets in Campaigns 1-8 (~88% of the full target sample) using colors, proper motions, spectroscopy, parallaxes, and galactic population synthesis models, with typical uncertainties for G-type stars of ~3% in Teff, ~0.3dex in logg~40% in radius, ~10% in mass, and ~40% in distance. Our results show that stars targeted by K2 are dominated by K-M dwarfs (~41% of all selected targets), F-G dwarfs (~36%), and K giants (~21%), consistent with key K2 science programs to search for transiting exoplanets and galactic archeology studies using oscillating red giants. However, we find significant variation of the fraction of cool dwarfs with galactic latitude, indicating a target selection bias due to interstellar reddening and increased contamination by giant stars near the galactic plane. We discuss possible systematic errors in the derived stellar properties, and differences with published classifications for K2 exoplanet host stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/173
- Title:
- Kepler asteroseismic LEGACY sample. II.
- Short Name:
- J/ApJ/835/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens of individual oscillation frequencies extracted from the time series of each star among seven modeling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics, and analysis methods employed by the different teams. Average uncertainties are of the order of ~2% in radius, ~4% in mass, and ~10% in age, making this the best-characterized sample of main-sequence stars available to date. Our predicted initial abundances and mixing-length parameters are checked against inferences from chemical enrichment laws {Delta}Y/{Delta}Z and predictions from 3D atmospheric simulations. We test the accuracy of the determined stellar properties by comparing them to the Sun, angular diameter measurements, Gaia parallaxes, and binary evolution, finding excellent agreement in all cases and further confirming the robustness of asteroseismically determined physical parameters of stars when individual frequencies of oscillation are available. Baptised as the Kepler dwarfs LEGACY sample, these stars are the solar-like oscillators with the best asteroseismic properties available for at least another decade. All data used in this analysis and the resulting stellar parameters are made publicly available for the community.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/2636
- Title:
- Kepler-10 chemical composition
- Short Name:
- J/MNRAS/456/2636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality Canada-France-Hawaii Telescope, Hobby-Eberly Telescope and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ~13 Earth masses, while the two known planets in Kepler-10 system have a combined ~20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors [e.g. planet signature, stellar age, stellar birth location and Galactic chemical evolution (GCE)] could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/149
- Title:
- Kepler Follow-up Observation Program. II. Spectro.
- Short Name:
- J/ApJ/861/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from spectroscopic follow-up observations of stars identified in the Kepler field and carried out by teams of the Kepler Follow-up Observation Program. Two samples of stars were observed over 6yr (2009-2015): 614 standard stars (divided into "platinum" and "gold" categories) selected based on their asteroseismic detections and 2667 host stars of Kepler Objects of Interest (KOIs), most of them planet candidates. Four data analysis pipelines were used to derive stellar parameters for the observed stars. We compare the Teff, log(g), and [Fe/H] values derived for the same stars by different pipelines; from the average of the standard deviations of the differences in these parameter values, we derive error floors of ~100K, 0.2dex, and 0.1dex for Teff, log(g), and [Fe/H], respectively. Noticeable disagreements are seen mostly at the largest and smallest parameter values (e.g., in the giant star regime). Most of the log(g) values derived from spectra for the platinum stars agree on average within 0.025dex (but with a spread of 0.1-0.2dex) with the asteroseismic log(g) values. Compared to the Kepler Input Catalog (KIC), the spectroscopically derived stellar parameters agree within the uncertainties of the KIC but are more precise and thus an important contribution toward deriving more reliable planetary radii.
938. Kepler Input Catalog
- ID:
- ivo://CDS.VizieR/V/133
- Title:
- Kepler Input Catalog
- Short Name:
- V/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets. The KIC, or Kepler Input Catalog, is the primary source of information about objects observed as part of the ground-based Kepler Spectral Classification Program (SCP) in preparation for the selection of Kepler PI and GO targets. The KIC lists objects down to 21mag, but it is not complete to this limit. Light from only about 1/3 of these objects falls on the Kepler CCD detector. A small number of the KIC objects are calibration objects distributed across the sky. For this reason the full KIC should never be used for Kepler target selection.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A112
- Title:
- Kepler LEGACY stars high-precision abundances
- Short Name:
- J/A+A/608/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HARPS-N spectra with S/N>250 and MARCS model atmospheres were used to derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten stars from the Kepler LEGACY sample including the binary pair 16 Cyg A and B. Stellar gravities and ages were obtained from seismic data and effective temperatures were determined by comparing non-LTE iron abundances derived from FeI and FeII lines. Available non-LTE corrections were also applied when deriving abundances of the other elements.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/130
- Title:
- Kepler multiple transiting planet systems
- Short Name:
- J/ApJ/813/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler mission provides a wealth of multiple transiting planet systems (MTPSs). The formation and evolution of multi-planet systems are likely to be influenced by companion stars given the abundance of multiple stellar systems. We study the influence of stellar companions by measuring the stellar multiplicity rate of MTPSs. We select 138 bright (K_P_<13.5) Kepler MTPSs and search for stellar companions with adaptive optics (AO) imaging data and archival radial velocity data. We obtain new AO images for 73 MTPSs. Other MTPSs in the sample have archival AO imaging data from the Kepler Community Follow-up Observation Program. From these imaging data, we detect 42 stellar companions around 35 host stars. For stellar separation 1 AU<a<100 AU, the stellar multiplicity rate is 5.2+/-5.0% for MTPSs, which is 2.8{sigma} lower than 21.1+/-2.8% for the control sample, i.e., the field stars in the solar neighborhood. We identify two origins for the deficit of stellar companions within 100 AU of MTPSs: (1) a suppressive planet formation and (2) the disruption of orbital coplanarity due to stellar companions. To distinguish between the two origins, we compare the stellar multiplicity rates of MTPSs and single transiting planet systems (STPSs). However, current data are not sufficient for this purpose. For 100 AU<a<2000 AU, the stellar multiplicity rates are comparable for MTPSs (8.0+/-4.0%), STPSs (6.4+/-5.8%), and the control sample (12.5+/-2.8%).