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4671. White-dwarf + main-sequence binaries in SDSS DR9
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.
4672. White dwarf population of Messier 67
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.
4673. White dwarf-red dwarf binaries in the SDSS
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.
4674. Wide binaries in Tycho-Gaia: search method
ID:
ivo://CDS.VizieR/J/MNRAS/472/675
Title:
Wide binaries in Tycho-Gaia: search method
Short Name:
J/MNRAS/472/675
Date:
21 Oct 2021
Publisher:
CDS
Description:
We mine the Tycho-Gaia astrometric solution (TGAS) catalogue for wide stellar binaries by matching positions, proper motions and astrometric parallaxes. We separate genuine binaries from unassociated stellar pairs through a Bayesian formulation that includes correlated uncertainties in the proper motions and parallaxes. Rather than relying on assumptions about the structure of the Galaxy, we calculate Bayesian priors and likelihoods based on the nature of Keplerian orbits and the TGAS catalogue itself. We calibrate our method using radial velocity measurements and obtain 7108 high-confidence candidate wide binaries with projected separations s<~1pc. The normalization of this distribution suggests that at least 0.7 per cent of TGAS stars have an associated, distant TGAS companion in a wide binary. We demonstrate that Gaia's astrometry is precise enough that it can detect projected orbital velocities in wide binaries with orbital periods as large as 10^6^yr. For pairs with s<~4x10^4^au, characterization of random alignments indicates our contamination to be 5-10 per cent. For s<~5x10^3^au, our distribution is consistent with Opik's law. At larger separations, the distribution is steeper and consistent with a power-law P(s){propto}s^-1.6^; there is no evidence in our data of any bimodality in this distribution for s<~1pc. Using radial velocities, we demonstrate that at large separations, i.e. of order s~1pc and beyond, any potential sample of genuine wide binaries in TGAS cannot be easily distinguished from ionized former wide binaries, moving groups or contamination from randomly aligned stars.
4675. Wide field imagers ground-based astrometry. V.
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.
4676. Wide-field optical imaging of 4 fields
ID:
ivo://CDS.VizieR/J/MNRAS/416/927
Title:
Wide-field optical imaging of 4 fields
Short Name:
J/MNRAS/416/927
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present u-, g-, r-, i- and z-band optical images and associated catalogues taken primarily with the Isaac Newton Telescope Wide Field Camera on the European Large Area ISO Survey (ELAIS) N1 and N2, First Look Survey and Lockman Hole fields comprising a total of 1000h of integration time over 80deg^2^ and approximately 4.3 million objects. In this paper we outline the observations and data processing and characterize the completeness, reliability, photometric and astrometric accuracy of this data set. All images have been photometrically calibrated using the Sloan Digital Sky Survey and a uniform and homogeneous data set is composed over all the observed fields. Magnitude limits are u, g, r, i, z of 23.9, 24.5, 24.0, 23.3, 22.0 (AB, 5{sigma}). These data have been used for optical identification of past and ongoing projects including the surveys ELAIS, Spitzer Wide-Area Infrared Extragalactic Survey, Spitzer Extragalactic Representative Volume Survey and Herschel Multi-tiered Extragalactic Survey.
4677. Wide-field photometry of the GC Palomar 5
ID:
ivo://CDS.VizieR/J/ApJ/819/1
Title:
Wide-field photometry of the GC Palomar 5
Short Name:
J/ApJ/819/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of wide-field photometric surveys of the Palomar 5 globular cluster and its stellar stream, based on g- and r-band measures together with narrow-band DDO 51 photometry. In this first study, we use the deep (g, r) data to measure the incidence of gaps and peaks along the stream. Examining the star-counts profile of the stream plus contaminating populations, we find no evidence for significant underdensities, and find only a single significant overdensity. This is at odds with earlier studies based on matched-filter maps derived from shallower SDSS data if the contaminating population possesses plausible spatial properties. The lack of substantial substructure along the stream may be used in future dynamical simulations to examine the incidence of dark matter sub-halos in the Galactic halo. We also present a measurement of the relative distances along the stream, which we use to create the deepest wide-field map of this system to date. Universe}
4678. Wide-Field Plate Database
ID:
ivo://CDS.VizieR/VI/90
Title:
Wide-Field Plate Database
Short Name:
VI/90
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Wide-Field Plate Database (WFPDB) contains the descriptive information for the astronomical wide-field (~>1deg.) photographic observations stored in numerous archives all over the world. When finished it will provide an on-line access to the information for about 2 million observations from nearly 300 archives, obtained since the end of last century. Presently the WFPDB includes data for about 330 000 observations from 57 plate catalogues. About 120 000 observations more from 32 plate catalogs are in preparation to be included in the database. The WFPDB provides for each observation information for the corresponding archive, the parameters of the observational instrument, the observation parameters (position on sky, observation time, object name, method, exposure time, emulsion type, filter type, spectral band, plate size), as well as data on the plate quality, comments, and observers. Data on the plate availability and digitization will be supplemented in the WFPDB in the future.
4679. Wide-field spectrosc. survey of GCs in Virgo cluster
ID:
ivo://CDS.VizieR/J/ApJ/835/212
Title:
Wide-field spectrosc. survey of GCs in Virgo cluster
Short Name:
J/ApJ/835/212
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a wide-field spectroscopic survey of globular clusters (GCs) in the Virgo cluster. We obtain spectra for 201 GCs and 55 ultracompact dwarfs (UCDs) using Hectospec on the Multiple-Mirror Telescope and derive their radial velocities. We identify 46 genuine intracluster GCs (IGCs), not associated with any Virgo galaxies, using the 3D GMM test on the spatial and radial velocity distribution. They are located at a projected distance 200kpc<~R<~500kpc from the center of M87. The radial velocity distribution of these IGCs shows two peaks, one at v_r_=1023km/s, associated with the Virgo main body, and another at v_r_=36km/s, associated with the infalling structure. The velocity dispersion of the IGCs in the Virgo main body is {sigma}_GC_~314km/s, which is smoothly connected to the velocity dispersion profile of M87 GCs but is much lower than that of dwarf galaxies in the same survey field, {sigma}_dwarf_~608km/s. The UCDs are more centrally concentrated on massive galaxies-M87, M86, and M84. The radial velocity dispersion of the UCD system is much smaller than that of dwarf galaxies. Our results confirm the large-scale distribution of Virgo IGCs indicated by previous photometric surveys. The color distribution of the confirmed IGCs shows a bimodality similar to that of M87 GCs. This indicates that most IGCs are stripped off dwarf galaxies and some off massive galaxies in the Virgo.
4680. Wide field ugriz photometry of 0.06<z<0.4 AGNs
ID:
ivo://CDS.VizieR/J/ApJ/800/93
Title:
Wide field ugriz photometry of 0.06<z<0.4 AGNs
Short Name:
J/ApJ/800/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of the large-scale environments of a sample of 12 broad line active galactic nuclei (AGNs) with 0.06<z<0.37 from deep images in the Sloan Digital Sky Survey u, g, r, and i filters taken with the 90Prime prime focus camera on the Steward Observatory Bok Telescope. We measure galaxy clustering around these AGNs using two standard techniques: correlation amplitude (B_gq_) and the two point correlation function. We find average correlation amplitudes for the 10 radio-quiet objects in the sample equal to (9+/-18, 144+/-114, -39+/-56, 295+/-260)Mpc^1.77^ in (u, g, r, i), all consistent with the expectation from galaxy clustering. Using a ratio of the galaxy-quasar cross-correlation function to the galaxy autocorrelation function, we calculate the relative bias of galaxies and AGNs, b_gq_. The bias in the u band, b_gq_=3.08+/-0.51 is larger compared to that calculated in the other bands, but it does not correlate with AGN luminosity, black hole mass, or AGN activity via the luminosity of the [OIII] emission line. Thus ongoing nuclear accretion activity is not reflected in the large scale environments from ~10h^-1^kpc to ~0.5h^-1^Mpc and may indicate a non-merger mode of AGN activity and/or a significant delay between galaxy mergers and nuclear activity in this sample of mostly radio-quiet quasars.