- ID:
- ivo://CDS.VizieR/J/MNRAS/510/4308
- Title:
- Local main-sequence stars with phot. metallicities
- Short Name:
- J/MNRAS/510/4308
- Date:
- 26 Jan 2022 00:36:57
- Publisher:
- CDS
- Description:
- We present a catalogue of 551214 main-sequence stars in the local (d<2kpc) Galactic thick disk and halo, based on a search of stars with large proper motions (>40.0mas/yr) in the Gaia Early Data Release 3. We derive photometric metallicity calibrated from the colour-luminosity-metallicity distribution of 20047 stars with spectroscopic metallicities, collected from various spectroscopic surveys, including SDSS SEGUE/APOGEE, GALAH DR3, and LAMOST DR6. We combine these results to construct an empirical colour- magnitude-metallicity grid, which can be used to estimate photometric metallicities for low-mass metal-poor stars of K and M subtypes from their absolute G magnitude and colour values. We find that low-mass, high-velocity stars in our catalogue share similar kinematics as reported in recent studies of more luminous Galactic halo stars. The pseudo-kinematic analysis of our sample recovers the main local halo structures, including the Gaia-Enceladus Stream and the Helmi stream; aside from these the local halo stars appear to show a remarkably smooth distribution in velocity space. Since the future Gaia data release will provide radial velocity measurements for only a small number of our sample, our catalogue provides targets of high interest for the future spectroscopic observation programs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/373/13
- Title:
- Lower main-sequence stars fundamental param.
- Short Name:
- J/MNRAS/373/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive an empirical effective temperature and bolometric luminosity calibration for G and K dwarfs, by applying our own implementation of the Infrared Flux Method to multiband photometry. Our study is based on 104 stars for which we have excellent BV(RI)_C_ JHK_s_ photometry, excellent parallaxes and good metallicities. Colours computed from the most recent synthetic libraries (ATLAS9 and MARCS) are found to be in good agreement with the empirical colours in the optical bands, but some discrepancies still remain in the infrared. Synthetic and empirical bolometric corrections also show fair agreement.
- ID:
- ivo://CDS.VizieR/J/A+A/471/499
- Title:
- Low-mass stars and brown dwarfs in Blanco 1
- Short Name:
- J/A+A/471/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a deep wide field optical survey of the young (~100-150Myr) open cluster Blanco 1 to study its low mass population well down into the brown dwarf regime and estimate its mass function over the whole cluster mass range.
- ID:
- ivo://CDS.VizieR/J/AJ/141/52
- Title:
- Low-mass visual companions to nearby G-dwarfs
- Short Name:
- J/AJ/141/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete census of wide visual companions to nearby G-dwarf stars can be achieved by selecting candidates from the Two Micron All Sky Survey (2MASS) Point-Source Catalog and checking their status by second-epoch imaging. Such data are obtained for 124 candidates with separations up to 20", 47 of which are shown to be new physical low-mass stellar companions. A list of visual binaries with G-dwarf primaries is produced by combining newly found companions with historical data.
- ID:
- ivo://CDS.VizieR/J/AJ/133/439
- Title:
- Luminosity function of M7-L8 ultracool dwarfs
- Short Name:
- J/AJ/133/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 20pc, volume-limited sample of M7-L8 dwarfs created through spectroscopic follow-up of sources selected from the Two Micron All Sky Survey Second Incremental Release Point Source Catalog. In this paper we present optical spectroscopy of 198 candidate nearby ultracool dwarfs, including 12 late-M and L dwarfs likely to be within 20pc of the Sun and 94 more distant late-type dwarfs. We have also identified five ultracool dwarfs with spectral signatures of low gravity. Combining these data with previous results, we define a sample of 99 ultracool dwarfs in 91 systems within 20pc. These are used to estimate the J- and K-band luminosity functions for dwarfs with optical spectral types between M7 and L8 (10.5<M_J_<15, 9.5<M_Ks_<13). We find a space density of 4.9x10^-3^/pc^3^ for late-M dwarfs (M7-M9.5) and a lower limit of 3.8x10^-3^/pc^3^ for L dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/40
- Title:
- Main-sequence A, F, G, and K stars photometry
- Short Name:
- J/ApJ/771/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main-sequence stars, ranging from spectral types A7 to K0, 5 of which are exoplanet host stars. We derive linear radii, effective temperatures, and absolute luminosities of the stars using Hipparcos parallaxes and measured bolometric fluxes. The new data are combined with previously published values to create an Angular Diameter Anthology of measured angular diameters to main-sequence stars (luminosity classes V and IV). This compilation consists of 125 stars with diameter uncertainties of less than 5%, ranging in spectral types from A to M. The large quantity of empirical data is used to derive color-temperature relations to an assortment of color indices in the Johnson (BVR_J_I_J_JHK), Cousins (R_C_I_C_), Kron (R_K_I_K_), Sloan (griz), and WISE (W_3_W_4_) photometric systems. These relations have an average standard deviation of ~3% and are valid for stars with spectral types A0-M4. To derive even more accurate relations for Sun-like stars, we also determined these temperature relations omitting early-type stars (T_eff_>6750K) that may have biased luminosity estimates because of rapid rotation; for this subset the dispersion is only ~2.5%. We find effective temperatures in agreement within a couple of percent for the interferometrically characterized sample of main-sequence stars compared to those derived via the infrared flux method and spectroscopic analysis.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A54
- Title:
- 61 main-sequence and subgiant oscillations
- Short Name:
- J/A+A/543/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars, thereby providing a way to probe the stars using asteroseismology We provide the mode frequencies of the oscillations of various stars required to perform a comparison with those obtained from stellar modelling. We used a time series of nine months of data for each star. The 61 stars observed were categorised in three groups: simple, F-like, and mixed-mode. The simple group includes stars for which the identification of the mode degree is obvious. The F-like group includes stars for which the identification of the degree is ambiguous. The mixed-mode group includes evolved stars for which the modes do not follow the asymptotic relation of low-degree frequencies. Following this categorisation, the power spectra of the 61 main-sequence and subgiant stars were analysed using both maximum likelihood estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths, and mode heights. We developed and describe a methodology for extracting a single set of mode frequencies from multiple sets derived by different methods and individual scientists. We report on how one can assess the quality of the fitted parameters using the likelihood ratio test and the posterior probabilities. We provide the mode frequencies of 61 stars (with their 1-{sigma} error bars), as well as their associated echelle diagrams.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A42
- Title:
- Main-sequence companions to massive Be stars
- Short Name:
- J/A+A/641/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 20% of all B-type stars are classical Be stars. The Be phenomenon is strongly correlated with rapid rotation, the origin of which remains unclear. It may be rooted in single- or binary-star evolution. In the framework of the binary channel, the initially more massive star transfers mass and angular momentum to the original secondary, which becomes a Be star. The system then evolves into a Be binary with a post-main-sequence companion, which may later be disrupted in a supernova event. Hence, if the binary channel dominates the formation of Be stars, one may expect a strong lack of close Be binaries with main sequence (MS) companions. Through an extensive, star-by-star review of the literature of a magnitude-limited sample of Galactic early-type Be stars, we investigate whether Be binaries with MS companions are known to exist. Our sample is constructed from the BeSS database and cross-matched with all available literature on the individual stars. Out of an initial list of 505 Be stars, we compile a final sample of 287 Galactic Be stars earlier than B1.5 with V<=12mag. Out of those, 13 objects were reported as Be binaries with known post-MS companions and 11 as binaries with unknown, uncertain or debated companions. We find no confirmed reports of Be binaries with MS companions. For the remaining 263 targets, no significant reports of multiplicity exist in the literature, implying that they are either Be binaries with faint companions, or truly single. The clear lack of reported MS companions to Be stars, which stands in contrast to the high number of detected B+B MS binaries, strongly supports the hypothesis that early-type Be stars are binary interaction products that spun up after mass and angular momentum transfer from a companion star. Taken at face value, our results may suggest that a large majority of the early-type Be stars have formed through binary mass-transfer.
- ID:
- ivo://CDS.VizieR/J/AJ/156/27
- Title:
- Masses & radii of 4 VLM stars in EB systems
- Short Name:
- J/AJ/156/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries (EBs) with one of the companions as very low-mass stars (VLMSs; or M dwarfs) are testbeds to substantiate stellar models and evolutionary theories. Here we present four EB candidates with F-type primaries, namely, SAO 106989, HD 24465, EPIC 211682657, and HD 205403, identified from different photometry missions, SuperWASP, Kilodegree Extremely Little Telescope (KELT), Kepler 2 (K2), and Solar Terrestrial Relations Observatory (STEREO). Using the high-resolution spectrograph PRL Advanced Radial velocity Abu-sky Search at the 1.2 m telescope at Mount Abu, Rajasthan, India, we hereby report the detection of four VLMSs as companions to the four EBs. We performed spectroscopic analysis and found the companion masses to be 0.256+/-0.005, 0.233+/-0.002, 0.599+/-0.017, and 0.406+/-0.005 M_{sun}_ for SAO 106989, HD 24465, EPIC 211682657, and SAO 106989B, respectively. We determined orbital periods of 4.39790+/-0.00001, 7.19635+/-0.00002, 3.142023+/-0.000003, and 2.444949+/-0.000001 days and eccentricities of 0.248+/-0.005, 0.208+/-0.002, 0.0097+/- 0.0008, and 0.002+/-0.002 for EBs SAO 106989, HD 24465, EPIC 211682657, and HD 205403, respectively. The radii derived by modeling the photometry data are 0.326+/-0.012 R_{sun}_ for SAO 106989, 0.244+/-0.001 R_{sun}_ for HD 24465B, 0.566+/-0.005 R_{sun}_ for EPIC 211682657B, and 0.444+/-0.014 R_{sun}_ for HD 205403B. The radii of HD 24465B and EPIC 211682657B have been measured by precise Kepler photometry and are consistent with theory within the error bars. However, the radii of SAO 106989B and HD 205403B, measured by KELT and STEREO photometry, are 17%-20% higher than those predicted by theory. A brief comparison of the results of the current work is made with the M dwarfs already studied in the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1817
- Title:
- 2MASS/SDSS data for 806 ultracool dwarfs
- Short Name:
- J/MNRAS/404/1817
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify 806 ultracool dwarfs (of which 34 are newly discovered L dwarfs) from their Sloan Digital Sky Survey (SDSS) riz photometry and obtain proper motions through cross-matching with the United Kingdom Infrared Telescope Infrared Deep Sky Survey (UKIDSS) and Two-Micron All-Sky Survey (2MASS). Proper-motion and distance constraints show that nine of our ultracool dwarfs are members of widely separated binary systems.
