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3541. DB white dwarfs from the Hamburg/ESO survey
ID:
ivo://CDS.VizieR/J/A+A/363/1040
Title:
DB white dwarfs from the Hamburg/ESO survey
Short Name:
J/A+A/363/1040
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of 40 cool helium-rich white dwarfs found in the Hamburg/ESO survey. They were selected for follow-up spectroscopy because of their U-B colour below -0.18, the absence of strong absorption lines, and a continuum shape similar to that of a quasar. Effective temperatures for individual stars were determined by fitting model atmospheres of nearly pure helium with a small admixture of hydrogen. As a consequence of the selection criteria all but one sample stars have T_eff_ below 20000K. Four stars clearly show helium and hydrogen lines in their spectra. In the spectra of another three, helium, hydrogen, and metal lines can be detected. For these stars hydrogen and metal abundances were also determined by fitting appropriate model atmospheres containing these elements. Seven sample stars most likely have helium-rich atmospheres but do not show any helium lines. They either have featureless spectra or show calcium lines.
3542. DB white dwarfs in SDSS DR10 and DR12
ID:
ivo://CDS.VizieR/J/A+A/583/A86
Title:
DB white dwarfs in SDSS DR10 and DR12
Short Name:
J/A+A/583/A86
Date:
21 Oct 2021
Publisher:
CDS
Description:
White dwarfs with helium-dominated atmospheres (spectral types DO, DB) comprise approximately 20% of all white dwarfs. There are fewer studies than of their hydrogen-rich counterparts (DA) and thus several questions remain open. Among these are the total masses and the origin of the hydrogen traces observed in a large number and the nature of the deficit of DBs in the range from 30000-45000K. We use the largest-ever sample (by a factor of 10) provided by the Sloan Digital Sky Survey (SDSS) to study these questions. The photometric and spectroscopic data of 1107 helium-rich objects from the SDSS are analyzed using theoretical model atmospheres. Along with the effective temperature and surface gravity, we also determine hydrogen and calcium abundances or upper limits for all objects. The atmosphere models are extended with envelope calculations to determine the extent of the helium convection zones and thus the total amount of hydrogen and calcium present.
3543. DB white dwarfs with SDSS and Gaia data
ID:
ivo://CDS.VizieR/J/ApJ/882/106
Title:
DB white dwarfs with SDSS and Gaia data
Short Name:
J/ApJ/882/106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive analysis of DB white dwarfs drawn from the Sloan Digital Sky Survey, based on model fits to ugriz photometry and medium-resolution spectroscopy from the Sloan Digital Sky Survey. We also take advantage of the exquisite trigonometric parallax measurements recently obtained by the Gaia mission. Using the so-called photometric and spectroscopic techniques, we measure the atmospheric and physical parameters of each object in our sample (Teff, logg, H/He, Ca/He, R, M), and compare the values obtained from both techniques in order to assess the precision and accuracy of each method. We then explore in great detail the surface gravity, stellar mass, and hydrogen abundance distributions of DB white dwarfs as a function of effective temperature. We present some clear evidence for a large population of unresolved double-degenerate binaries composed of DB+DB and even DB+DA white dwarfs. In the light of our results, we finally discuss the spectral evolution of DB white dwarfs, in particular the evolution of the DB-to-DA ratio as a function of Teff, and we revisit the question of the origin of hydrogen in DBA white dwarfs.
3544. 2-D Classification, Vilnius Photometry M56 Region
ID:
ivo://CDS.VizieR/II/130
Title:
2-D Classification, Vilnius Photometry M56 Region
Short Name:
II/130
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue gives the seven-color photometry in the Vilnius system stars and two-dimensional classification of 752 stars. Photographically determined magnitudes obtained by COSMOS (MacGillivray and Stobie 1984) on the Schmidt plates were input into software described by Smriglio et al. (1986) as a method of automated two-dimensional stellar classification in the Vilnius seven-color intermediate band photometric system (Straizys and Zdanavicius 1970). A region of approximately two square degrees in Lyra centered on RA(1950) = 19h14.6min, DE(1950) = 30deg05' in the direction of the globular cluster M56 was studied and the two-dimensional classification of 752 stars in the magnitude range V = 11 to 15 mag was studied. The photometric system, the method of reduction, the classification procedure and errors were described by Smriglio et al. (1986). The number of stars for which all the six color indices in the Vilnius system are available is close to 3000, but the number of stars which have received two dimensional classification is 752. The success rate of classification appears to be high for stars brighter than V = 15.0 mag for which photometric accuracy is better than +-5%.
3545. DCld303-14.8 & Thumbprint Nebula JHKs phot.
ID:
ivo://CDS.VizieR/J/A+A/463/1029
Title:
DCld303-14.8 & Thumbprint Nebula JHKs phot.
Short Name:
J/A+A/463/1029
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of radial density structure of the star forming globule, DCld303.8-14.2 (DC303), and a non-star forming globule, Thumbprint Nebula (TPN), using near-infrared data taken with the ISAAC instrument on the Very Large Telescope. We derive the extinction through the globules using the color excess technique and examine the radial density distribution using Bonnor-Ebert and power-law models.
3546. 400d Cluster Survey Weak Lensing Programme II
ID:
ivo://CDS.VizieR/J/A+A/546/A79
Title:
400d Cluster Survey Weak Lensing Programme II
Short Name:
J/A+A/546/A79
Date:
21 Oct 2021
Publisher:
CDS
Description:
Evolution in the mass function of galaxy clusters sensitively traces both the expansion history of the Universe and cosmological structure formation. Robust cluster mass determinations are a key ingredient for a reliable measurement of this evolution, especially at high redshift. Weak gravitational lensing is a promising tool for, on average, unbiased mass estimates. This weak lensing project aims at measuring reliable weak lensing masses for a complete X-ray selected sample of 36 high redshift (0.35<z<0.9) clusters. The goal of this paper is to demonstrate the robustness of the methodology against commonly encountered problems, including pure instrumental effects, the presence of bright (8-9mag) stars close to the cluster centre, ground based measurements of high-z (z~0.8) clusters, and the presence of massive unrelated structures along the line-sight.
3547. 3D-corrected oxygen abundances for halo stars
ID:
ivo://CDS.VizieR/J/A+A/624/A44
Title:
3D-corrected oxygen abundances for halo stars
Short Name:
J/A+A/624/A44
Date:
21 Oct 2021
Publisher:
CDS
Description:
Measurable amounts of Be could have been synthesised primordially if the Universe were non-homogeneous or in the presence of late decaying relic particles. We investigate the Be abundance in the extremely metal-poor star 2MASS J1808-5104 ([Fe/H]=-3.84) with the aim of constraining inhomogeneities or the presence of late decaying particles. High resolution, high signal-to-noise ratio (S/N) UV spectra were acquired at ESO with the Kueyen 8.2m telescope and the UVES spectrograph. Abundances were derived using several model atmospheres and spectral synthesis code. We measured log(Be/H)=-14.3 from a spectrum synthesis of the region of the Be line. Using a conservative approach, however we adopted an upper limit two times higher, i.e. log(Be/H)<-14.0. We measured the O abundance from UV-OH lines and find [O/H]=-3.46 after a 3D correction. Our observation reinforces the existing upper limit on primordial Be. There is no observational indication for a primordial production of 9Be. This places strong constraints on the properties of putative relic particles. This result also supports the hypothesis of a homogeneous Universe, at the time of nucleosynthesis. Surprisingly, our upper limit of the Be abundance is well below the Be measurements in stars of similar [O/H]. This may be evidence that the Be-O relation breaks down in the early Galaxy, perhaps due to the escape of spallation products from the gas clouds in which stars such as 2MASS J1808-5104 have formed.
3548. 2D decomposition of CALIFA galaxies
ID:
ivo://CDS.VizieR/J/A+A/598/A32
Title:
2D decomposition of CALIFA galaxies
Short Name:
J/A+A/598/A32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a two-dimensional multi-component photometric decomposition of 404 galaxies from the Calar Alto Legacy Integral Field Area Data Release 3 (CALIFA-DR3). They represent all possible galaxies with no clear signs of interaction and not strongly inclined in the final CALIFA data release. Galaxies are modelled in the g, r, and i Sloan Digital Sky Survey (SDSS) images including, when appropriate, a nuclear point source, bulge, bar, and an exponential or broken disc component. We use a human-supervised approach to determine the optimal number of structures to be included in the fit. The dataset, including the photometric parameters of the CALIFA sample, is released together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(M*/M_{sun}_)>11), the galaxy population is dominated by galaxies modelled with a single Sersic or a bulge+disc with a bulge-to-total (B/T) luminosity ratio B/T>0.2. At intermediate masses (9.5<log(M*/M_{sun}_)<11), galaxies described with bulge+disc but B/T<0.2 are preponderant, whereas, at the low mass end (log(M*/M_{\sun}_)<9.5), the prevailing population is constituted by galaxies modelled with either pure discs or nuclear point sources+discs (i.e., no discernible bulge). The analyses of the extended multi-component radial profile result in a volume-corrected distribution of 62%, 28%, and 10% for the so-called Type I (pure exponential), Type II (down-bending), and Type III (up-bending) disc profiles, respectively. These fractions are in discordance with previous findings. We argue that the different methodologies used to detect the breaks are the main cause for these differences.
3549. 3D density & temp. profiles of 5 clusters
ID:
ivo://CDS.VizieR/J/A+A/617/A64
Title:
3D density & temp. profiles of 5 clusters
Short Name:
J/A+A/617/A64
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed study of the integrated total hydrostatic mass profiles of the five most massive (M_500_^SZ^>5x10^14^M_{sun}_) galaxy 500 clusters selected at z~1 via the Sunyaev-Zel'dovich effect. These objects represent an ideal laboratory to test structure formation models where the primary driver is gravity. Optimally exploiting spatially-resolved spectroscopic information from XMM-Newton and Chandra observations, we used both parametric (forward, backward) and non-parametric methods to recover the mass profiles, finding that the results are extremely robust when density and temperature measurements are both available. Our X-ray masses at R_500_ are higher than the weak lensing masses obtained from the Hubble Space Telescope (HST), with a mean ratio of 1.39^+0.47^_-0.35_. This offset goes in the opposite direction to that expected in a scenario where the hydrostatic method yields a biased, underestimated, mass. We investigated halo shape parameters such as sparsity and concentration, and compared to local X-ray selected clusters, finding hints for evolution in the central regions (or for selection effects). The total baryonic content is in agreement with the cosmic value at R_500_. Comparison with numerical simulations shows that the mass distribution and concentration are in line with expectations. These results illustrate the power of X-ray observations to probe the statistical properties of the gas and total mass profiles in this high-mass, high-redshift regime.
3550. DDO Photoelectric Photometric Catalog
ID:
ivo://CDS.VizieR/II/164
Title:
DDO Photoelectric Photometric Catalog
Short Name:
II/164
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue collects the DDO photometric data published in the astronomical literature until the end of 1988, and contains 8034 DDO measurements, concerning 6139 stars. The DDO 6-filter has the following peak wavelengths and widths: ------------------------ Filter Peak Width [nm] [nm] ------------------------ 35 346.0 38.3 38 381.5 33.0 41 416.6 8.3 42 425.7 7.3 45 451.7 7.6 48 488.6 18.6 51 (*) 513.0 13.4 ------------------------ (*) additional to DDO.

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