- ID:
- ivo://CDS.VizieR/J/MNRAS/433/3398
- Title:
- White dwarf main-sequence binaries
- Short Name:
- J/MNRAS/433/3398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectroscopic catalogue of white dwarf main-sequence (WDMS) binaries from the Sloan Digital Sky Survey (SDSS) is the largest and most homogeneous sample of compact binary stars currently known. However, because of selection effects, the current sample is strongly biased against systems containing cool white dwarfs and/or early-type companions, which are predicted to dominate the intrinsic population. In this study, we present colour selection criteria that combines optical (ugriz DR8 SDSS) plus infrared (yjhk DR9 UKIRT Infrared Sky Survey, JHK Two Micron All Sky Survey and/or W1W2 Wide-Field Infrared Survey Explorer) magnitudes to select 3419 photometric candidates of harbouring cool white dwarfs and/or dominant (M dwarf) companions. We demonstrate that 84 percent of our selected candidates are very likely genuine WDMS binaries, and that the white dwarf effective temperatures and secondary star spectral types of 71 percent of our selected sources are expected to be below <~10000-15000K, and concentrated at ~M2-3, respectively. We also present an updated version of the spectroscopic SDSS WDMS binary catalogue, which incorporates 47 new systems from SDSS DR8. The bulk of the DR8 spectroscopy is made up of main-sequence stars and red giants that were targeted as part of the Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey, therefore the number of new spectroscopic WDMS binaries in DR 8 is very small compared to previous SDSS data releases. Despite their low number, DR8 WDMS binaries are found to be dominated by systems containing cool white dwarfs and therefore represent an important addition to the spectroscopic sample. The updated SDSS DR8 spectroscopic catalogue of WDMS binaries consists of 2316 systems. We compare our updated catalogue with recently published lists of WDMS binaries and conclude that it currently represents the largest, most homogeneous and cleanest sample of spectroscopic WDMS binaries from SDSS.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/1331
- Title:
- White-dwarf + main-sequence binaries in SDSS DR9
- Short Name:
- J/MNRAS/445/1331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 227 new spectroscopic white-dwarf + main-sequence (WDMS) binaries from the ninth data release (DR9) of the Sloan Digital Sky Survey (SDSS). The SDSS spectra of the newly found WDMS binaries with a DA white dwarf and an M-dwarf are analysed based on a spectral decomposition/fitting method. We obtain the effective temperatures, surface gravities and masses of the white dwarf, together with the spectral types and metallicities of the secondary star. Two independent distance estimates are derived from the flux-scaling factors between the WDMS SDSS spectra and the white dwarf and M-dwarf model spectra. We find that about 25 per cent of the newly found WDMS binaries show a significant discrepancy between the two distance estimates. This might be caused by the effects of M-dwarf stellar activity or irradiation of the M-dwarf companions by the white dwarf. The stellar parameter distributions are used to investigate the global properties of the newly found WDMS binaries. We find that the WDMS binaries with a low signal-to-noise ratio (S/N<=4.0) usually have a massive DA white dwarf component with a higher surface gravity, and the metallicity is usually significantly different from solar. This suggests that the observational selection effects and the spectral S/N of the WDMS binaries have a significant influence on the determinations of these physical parameters of WDMS binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/867/62
- Title:
- White dwarf population of Messier 67
- Short Name:
- J/ApJ/867/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- White dwarfs (WDs) are excellent forensic tools for studying end-of-life issues surrounding low- and intermediate-mass stars, and the old, solar metallicity open star cluster Messier 67 is a proven laboratory for the study of stellar evolution for solar-type stars. In this paper, we present a detailed spectroscopic study of brighter (M_g_<=12.4) WDs in Messier 67, and in combination with previously published proper motion membership determinations, we identify a clean, representative sample of cluster WDs, including 13 members with hydrogen-dominated atmospheres, at least one of which is a candidate double degenerate, and 5 members with helium-dominated atmospheres. Using this sample we test multiple predictions surrounding the final stages of stellar evolution in solar-type stars. In particular, the stochasticity of the integrated mass lost by ~1.5 solar mass stars is less than 7% of the WD remnant mass. We identify WDs likely resulting from binary evolution, including at least one blue straggler remnant and two helium-core WDs. We observe no evidence of a significant population of helium-core WDs formed by enhanced mass loss on the red giant branch of the cluster. The distribution of WD atmospheric compositions is fully consistent with that in the field, limiting proposed mechanisms for the suppression of helium atmosphere WD formation in star clusters. In short, the WD population of Messier 67 is fully consistent with basic predictions of single- and multiple-star stellar evolution theories for solar metallicity stars.
- ID:
- ivo://CDS.VizieR/J/A+A/486/843
- Title:
- White dwarf-red dwarf binaries in the SDSS
- Short Name:
- J/A+A/486/843
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To reduce contamination by more distant sources, such as quasars, we have selected candidate white dwarf-red dwarf binaries from the catalogue of proper motion stars drawn from the intersection of the Sloan Digital Sky Survey (SDSS) and the USNO-B1.0 catalogue.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/1988
- Title:
- White dwarfs in Galactic plane
- Short Name:
- J/MNRAS/457/1988
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the prospects for systematic searches of white dwarfs at low Galactic latitudes, using the VLT Survey Telescope H{alpha} Photometric Survey of the Galactic plane and Bulge (VPHAS+). We targeted 17 white dwarf candidates along sightlines of known open clusters, aiming to identify potential cluster members. We confirmed all the 17 white dwarf candidates from blue/optical spectroscopy, and we suggest five of them to be likely cluster members. We estimated progenitor ages and masses for the candidate cluster members, and compare our findings to those for other cluster white dwarfs. A white dwarf in NGC 3532 is the most massive known cluster member (1.13M_{sun}_), likely with an oxygen-neon core, for which we estimate an M_{sun}_ progenitor, close to the mass-divide between white dwarf and neutron star progenitors. A cluster member in Ruprecht 131 is a magnetic white dwarf, whose progenitor mass exceeded 2-3M_{sun}_. We stress that wider searches, and improved cluster distances and ages derived from data of the ESA Gaia mission, will advance the understanding of the mass-loss processes for low- to intermediate-mass stars.
- ID:
- ivo://CDS.VizieR/J/AJ/143/50
- Title:
- White dwarfs in 47 Tuc (NGC 104) with HST
- Short Name:
- J/AJ/143/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new distance determination to the Galactic globular cluster 47 Tucanae (47 Tuc, NGC 104) by fitting the spectral energy distributions of its white dwarfs (WDs) to pure hydrogen atmosphere WD models. Our photometric data set is obtained from a 121-orbit Hubble Space Telescope program using the Wide Field Camera 3 UVIS/IR channels, capturing F390W, F606W, F110W, and F160W images. These images cover more than 60 arcmin^2^ and extend over a radial range of 5-13.7arcmin (6.5-17.9pc) within the globular cluster. Using a likelihood analysis, we obtain a best-fitting unreddened distance modulus of (m-M)_o_=13.36+/-0.02+/-0.06 corresponding to a distance of 4.69+/-0.04+/-0.13kpc, where the first error is random and the second is systematic. We also search the WD photometry for infrared excess in the F160W filter, indicative of low-mass companions, and find no convincing cases within our sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/586/1356
- Title:
- White dwarfs with cool companions
- Short Name:
- J/ApJ/586/1356
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (IR) magnitudes for all white dwarfs (selected from the catalog of McCook & Sion, 1999, See Cat. <III/235>) contained in the Two Micron All-Sky Survey second incremental data release (2MASS 2IDR, Cat. <II/241>). We show that the near-IR color-color diagram is an effective means of identifying candidate binary stars containing a WD and a low-mass, main-sequence star. The loci of single WDs and WD+red dwarf binaries occupy distinct regions of the near-IR color-color diagram. We recovered all known unresolved WD+red dwarf binaries located in the 2IDR sky coverage and also identified as many new candidate binaries (47 new candidates out of 95 total). Using observational near-IR data for WDs and M-L dwarfs, we have compared a sample of simulated WD+red dwarf binaries with our 2MASS data. The colors of the simulated binaries are dominated by the low-mass companion through the late M to early L spectral types. As the spectral type of the companion becomes progressively later, however, the colors of unresolved binaries become progressively bluer. Binaries containing the lowest mass companions will be difficult to distinguish from single WDs solely on the basis of their near-IR colors.
- ID:
- ivo://CDS.VizieR/J/AJ/141/50
- Title:
- White-light flares on cool stars from Kepler
- Short Name:
- J/AJ/141/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for white-light flares on ~23000 cool dwarfs in the Kepler Quarter 1 long cadence data. We have identified 373 flaring stars, some of which flare multiple times during the observation period. We calculate relative flare energies, flare rates, and durations and compare these with the quiescent photometric variability of our sample.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1669
- Title:
- Wide-field CCD phot. around nine open clusters
- Short Name:
- J/AJ/132/1669
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we study the evolution of the core and corona of nine open clusters using the projected radial density profiles derived from homogeneous CCD photometric data obtained with the 105cm Kiso Schmidt telescope. The age and galactocentric distance of the target clusters vary from 16 to 2000Myr and 9 to 10.8kpc, respectively. Barring Be 62, which is a young open cluster, other clusters show a uniform reddening across the cluster region.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A80
- Title:
- Wide field imagers ground-based astrometry. V.
- Short Name:
- J/A+A/563/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-precision astrometry requires accurate point-spread function modeling and accurate geometric-distortion corrections. This paper demonstrates that it is possible to achieve both requirements with data collected at the High Acuity Wide-field K-band Imager (HAWK-I); a wide-field imager installed at the Nasmyth focus of UT4/VLT ESO 8m telescope. Our final astrometric precision reaches ~3mas per coordinate for a well exposed star in a single image, with a systematic error less than 0.1mas. We constructed calibrated astro-photometric catalogs and atlases of 7 fields: the Baade's window, NGC 6656, NGC 6121, NGC 6822, NGC 6388, NGC 104, and the James Webb Space Telescope calibration field (in the LMC). We make these catalogs and images electronically available to the community. Furthermore, as a demonstration of the efficacy of our approach, combining archival material taken with the optical wide-field imager at the MPI/ESO 2.2m with HAWK-I observations, we are able to achieve an excellent separation between cluster members and field objects for NGC 6656 and NGC 6121 with a time base-line of about 8 years. Using both HST and HAWK-I data, we also study the radial distribution of the SGB populations in NGC 6656 and conclude that the radial trend is flat, within our uncertains. We also provide membership probabilities for most of the stars in NGC 6656 and NGC 6121 catalogs and estimate membership for the published variable stars in these two fields.
