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3741. The DEBCat detached eclipsing binary catalogue
ID:
ivo://CDS.VizieR/V/152
Title:
The DEBCat detached eclipsing binary catalogue
Short Name:
V/152
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detached eclipsing binary star systems are our primary source of measured physical properties of normal stars. I introduce DEBCat: a catalog of detached eclipsing binaries with mass and radius measurements to the 2% precision necessary to put useful constraints on theoretical models of stellar evolution. The catalog was begun in 2006, as an update of the compilation by Andersen (1991A&ARv...3...91A). It now contains over 195 systems (2017/10/10), and new results are added on appearance in the refereed literature.
3742. The DEEP2-DR1 Photometric Catalog
ID:
ivo://CDS.VizieR/II/301
Title:
The DEEP2-DR1 Photometric Catalog
Short Name:
II/301
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Deep Extragalactic Evolutionary Probe (DEEP) is a multi-year program which uses the twin 10m Keck Telescopes and the Hubble Space Telescope (HST) to conduct a truly large-scale survey of distant, faint, field galaxies. The broad scientific goals include: the formation and evolution of galaxies, the origin of large-scale structure, the nature of the dark matter, and the geometry of the Universe. This project is led by the Lick Observatory at University of California (UC) Santa Cruz, in collaboration with UC Berkeley, University of Hawaii (UH) Manoa, Johns Hopkins University, University of Chicago and California Institute of Technology. The photometric data were taken with the CFH12K camera on the 3.6-meter Canada-France-Hawai'i Telescope. Each DEEP2 field is covered by multiple CFHT/CFH12K pointings with each pointing numbered within its respective
3743. The 2dF-SDSS QSO survey
ID:
ivo://CDS.VizieR/J/MNRAS/392/19
Title:
The 2dF-SDSS QSO survey
Short Name:
J/MNRAS/392/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG (luminous red galaxy) and QSO (2SLAQ) survey. This is a deep, 18<g<21.85 (extinction corrected), sample aimed at probing in detail the faint end of the broad line active galactic nuclei luminosity distribution at z<=2.6. The candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg2 and contains new spectra of 16326 objects, of which 8764 are QSOs and 7623 are newly discovered [the remainder were previously identified by the 2dF QSO Redshift Survey (2QZ) and SDSS]. The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission-line galaxies with a median redshift of z=0.22.
3744. The doubly lensed quasar SDSS J1001+5027
ID:
ivo://CDS.VizieR/J/A+A/557/A44
Title:
The doubly lensed quasar SDSS J1001+5027
Short Name:
J/A+A/557/A44
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents optical R-band light curves and the time delay of the doubly imaged gravitationally lensed quasar SDSS J1001+5027 at a redshift of 1.838. We have observed this target for more than six years, between March 2005 and July 2011, using the 1.2-m Mercator Telescope, the 1.5-m telescope of the Maidanak Observatory and the 2-m Himalayan Chandra Telescope. Our resulting light curves are composed of 443 independent epochs, and show strong intrinsic quasar variability, with an amplitude of the order of 0.2 magnitudes. From this data, we measure the time delay using five different methods, all relying on distinct approaches. One of these techniques is a new development presented in this paper. All our time-delay measurements are perfectly compatible. By combining them, we conclude that image A is leading B by 119.3+/-3.3 days (1{sigma}, 2.8%), including systematic errors. It has been shown recently that such accurate time-delay measurements offer a highly complementary probe of dark energy and spatial curvature, as they independently constrain the Hubble constant. The next mandatory step towards using SDSS J1001+5027 in this context will be the measurement of the redshift of the lensing galaxy, in combination with deep HST imaging.
3745. The edge of the young Galactic disk
ID:
ivo://CDS.VizieR/J/ApJ/718/683
Title:
The edge of the young Galactic disk
Short Name:
J/ApJ/718/683
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we report and discuss the detection of two distant diffuse stellar groups in the third Galactic quadrant. They are composed of young stars, with spectral types ranging from late O to late B, and lie at galactocentric distances between 15 and 20kpc. These groups are located in the area of two cataloged open clusters (VdB-Hagen 04 and Ruprecht 30), projected toward the Vela-Puppis constellations, and within the core of the Canis Major overdensity. Their reddening and distances have been estimated by analyzing their color-color and color-magnitude diagrams, derived from deep UBV photometry. The existence of young star aggregates at such extreme distances from the Galactic center challenges the commonly accepted scenario in which the Galactic disk has a sharp cutoff at about 14kpc from the Galactic center and indicates that it extends to much greater distances (as also supported by the recent detection of CO molecular complexes well beyond this distance). While the groups we find in the area of Ruprecht 30 are compatible with the Orion and Norma-Cygnus spiral arms, respectively, the distant group we identify in the region of VdB-Hagen 04 lies in the external regions of the Norma-Cygnus arm, at a galactocentric distance (~20kpc) where no young stars have been detected so far in the optical.
3746. The ELM survey. I. Low-mass white dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/723/1072
Title:
The ELM survey. I. Low-mass white dwarfs
Short Name:
J/ApJ/723/1072
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze radial velocity observations of the 12 extremely low-mass (ELM), with <=0.25M_{sun}_, white dwarfs (WDs) in the MMT Hypervelocity Star Survey. Eleven of the twelve WDs are binaries with orbital periods shorter than 14hr; the one non-variable WD is possibly a pole-on system among our non-kinematically selected targets. Our sample is unique: it is complete in a well-defined range of apparent magnitude and color. The orbital mass functions imply that the unseen companions are most likely other WDs, although neutron star companions cannot be excluded. Six of the eleven systems with orbital solutions will merge within a Hubble time due to the loss of angular momentum through gravitational wave radiation. The quickest merger is J0923+3028, a g=15.7 ELM WD binary with a 1.08hr orbital period and a <=130Myr merger time. The chance of a supernova Ia event among our ELM WDs is only 1%-7%, however. Three binary systems (J0755+4906, J1233+1602, and J2119-0018) have extreme mass ratios and will most likely form stable mass-transfer AM CVn systems. Two of these objects, SDSS J1233+1602 and J2119-0018, are the lowest surface gravity WDs ever found; both show CaII absorption likely from accretion of circumbinary material. We predict that at least one of our WDs is an eclipsing detached double WD system, important for constraining helium core WD models.
3747. The ELM Survey. VIII. Final double WD binaries
ID:
ivo://CDS.VizieR/J/ApJ/889/49
Title:
The ELM Survey. VIII. Final double WD binaries
Short Name:
J/ApJ/889/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final sample of 98 detached double white dwarf (WD) binaries found in the Extremely Low Mass (ELM) Survey, a spectroscopic survey targeting <0.3M_{sun}_ He-core WDs completed in the Sloan Digital Sky Survey footprint. Over the course of the survey we observed ancillary low-mass WD candidates like GD 278, which we show is a P=0.19d double WD binary, as well as candidates that turn out to be field blue straggler/subdwarf A-type stars with luminosities too high to be WDs given their Gaia parallaxes. Here, we define a clean sample of ELM WDs that is complete within our target selection and magnitude range 15<g_0_<20mag. The measurements are consistent with 100% of ELM WDs being 0.0089<P<1.5d double WD binaries, 35% of which belong to the Galactic halo. We infer that these are mostly He+CO WD binaries given the measurement constraints. The merger rate of the observed He+CO WD binaries exceeds the formation rate of stable mass-transfer AM CVn binaries by a factor of 25, and so the majority of He+CO WD binaries must experience unstable mass transfer and merge. The systems with the shortest periods, such as J0651+2844, are signature LISA verification binaries that can be studied with gravitational waves and light.
3748. The ELM survey. VII. 15 new ELM white dwarf cand.
ID:
ivo://CDS.VizieR/J/ApJ/818/155
Title:
The ELM survey. VII. 15 new ELM white dwarf cand.
Short Name:
J/ApJ/818/155
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of 15 extremely low-mass (5<logg<7) white dwarf (WD) candidates, 9 of which are in ultra-compact double-degenerate binaries. Our targeted extremely low-mass Survey sample now includes 76 binaries. The sample has a lognormal distribution of orbital periods with a median period of 5.4hr. The velocity amplitudes imply that the binary companions have a normal distribution of mass with 0.76 M_{sun}_ mean and 0.25M_{sun}_ dispersion. Thus extremely low-mass WDs are found in binaries with a typical mass ratio of 1:4. Statistically speaking, 95% of the WD binaries have a total mass below the Chandrasekhar mass, and thus are not type Ia supernova progenitors. Yet half of the observed binaries will merge in less than 6Gyr due to gravitational wave radiation; probable outcomes include single massive WDs and stable mass transfer AM CVn binaries.
3749. The ELM survey. V. White dwarf binaries
ID:
ivo://CDS.VizieR/J/ApJ/769/66
Title:
The ELM survey. V. White dwarf binaries
Short Name:
J/ApJ/769/66
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P<=1 day) binaries. Our sample includes four objects with remarkable logg=~5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times <10Gyr. Four have >~0.9M_{sun}_ companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the Extremely low mass (ELM) Survey to 54; 31 of these binaries will merge within a Hubble time.
3750. The ELQS in SDSS footprint. II. North Gal. Cap
ID:
ivo://CDS.VizieR/J/ApJ/863/144
Title:
The ELQS in SDSS footprint. II. North Gal. Cap
Short Name:
J/ApJ/863/144
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the North Galactic Cap sample of the Extremely Luminous Quasar Survey (ELQS-N), which targets quasars with M_1450_{<}-27 at 2.8<=z<5 in an area of ~7600deg^2^ of the Sloan Digital Sky Survey (SDSS) footprint with 90{deg}<RA<270{deg}. Based on a near-infrared/infrared JKW2 color cut, the ELQS selection efficiently uses random forest methods to classify quasars and to estimate photometric redshifts; this scheme overcomes some of the difficulties of pure optical quasar selection at z~3. As a result, we retain a completeness of >70% over z~3.0-5.0 at m_i_<~17.5, limited toward fainter magnitudes by the depth of the Two Micron All Sky Survey. The presented quasar catalog consists of a total of 270 objects, of which 39 are newly identified in this work with spectroscopy obtained at the Vatican Advanced Technology Telescope and the MMT 6.5m telescope. In addition to the high completeness, which allowed us to discover new quasars in the already well-surveyed SDSS North Galactic Cap, the efficiency of our selection is relatively high at ~79%. Using 120 objects of this quasar sample we are able to extend the previously measured optical quasar luminosity function (QLF) by one magnitude toward the bright end at 2.8<=z<=4.5. A first analysis of the QLF suggests a relatively steep bright-end slope of {beta}~-4 for this sample. This result contrasts with previous results in the same redshift range, which find a much flatter slope around {beta}~-2.5, but agrees with recent measurements of the bright-end slope at lower and higher redshifts. Our results constrain the bright-end slope at z=2.8-4.5 to {beta}{<}-2.94 with a 99% confidence.