scholarly journals Meet the family − the catalog of known hot subdwarf stars

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Stephan Geier ◽  
Roy H. Østensen ◽  
Peter Nemeth ◽  
Ulrich Heber ◽  
Nicola P. Gentile Fusillo ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Far Infrared ◽  
Sloan Digital Sky Survey ◽  
Proper Motions ◽  
Sky Survey ◽  
The Family ◽  
Quantitative Spectral Analysis ◽  
Hot Subdwarfs ◽  
Halo Population

AbstractIn preparation for the upcoming all-sky data releases of the Gaia mission, we compiled a catalog of known hot subdwarf stars and candidates drawn from the literature and yet unpublished databases. The catalog contains 5613 unique sources and provides multi-band photometry from the ultraviolet to the far infrared, ground based proper motions, classifications based on spectroscopy and colors, published atmospheric parameters, radial velocities and light curve variability information. Using several different techniques, we removed outliers and misclassified objects. By matching this catalog with astrometric and photometric data from the Gaia mission, we will develop selection criteria to construct a homogeneous, magnitude-limited all-sky catalog of hot subdwarf stars based on Gaia data. As first application of the catalog data, we present the quantitative spectral analysis of 280 sdB and sdOB stars from the Sloan Digital Sky Survey Data Release 7. Combining our derived parameters with state-of-the-art proper motions, we performed a full kinematic analysis of our sample. This allowed us to separate the first significantly large sample of 78 sdBs and sdOBs belonging to the Galactic halo. Comparing the properties of hot subdwarfs from the disk and the halo with hot subdwarf samples from the globular clusters ! Cen and NGC 2808, we found the fraction of intermediate He-sdOBs in the field halo population to be significantly smaller than in the globular clusters.

scholarly journals Meet the family − the catalog of known hot subdwarf stars

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Stephan Geier ◽  
Roy H. Østensen ◽  
Peter Nemeth ◽  
Ulrich Heber ◽  
Nicola P. Gentile Fusillo ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Far Infrared ◽  
Sloan Digital Sky Survey ◽  
Proper Motions ◽  
Sky Survey ◽  
The Family ◽  
Quantitative Spectral Analysis ◽  
Hot Subdwarfs ◽  
Halo Population

AbstractIn preparation for the upcoming all-sky data releases of the Gaia mission, we compiled a catalog of known hot subdwarf stars and candidates drawn from the literature and yet unpublished databases. The catalog contains 5613 unique sources and provides multi-band photometry from the ultraviolet to the far infrared, ground based proper motions, classifications based on spectroscopy and colors, published atmospheric parameters, radial velocities and light curve variability information. Using several different techniques, we removed outliers and misclassified objects. By matching this catalog with astrometric and photometric data from the Gaia mission, we will develop selection criteria to construct a homogeneous, magnitude-limited all-sky catalog of hot subdwarf stars based on Gaia data. As first application of the catalog data, we present the quantitative spectral analysis of 280 sdB and sdOB stars from the Sloan Digital Sky Survey Data Release 7. Combining our derived parameters with state-of-the-art proper motions, we performed a full kinematic analysis of our sample. This allowed us to separate the first significantly large sample of 78 sdBs and sdOBs belonging to the Galactic halo. Comparing the properties of hot subdwarfs from the disk and the halo with hot subdwarf samples from the globular clusters ω Cen and NGC 2808, we found the fraction of intermediate He-sdOBs in the field halo population to be significantly smaller than in the globular clusters.

scholarly journals Globular clusters and their contribution to the formation of the Galactic halo

2015 ◽  
Vol 11 (S317) ◽  
pp. 97-103
Author(s):  
Eugenio Carretta
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
New Paradigm ◽  
Multiple Populations ◽  
Weak Points ◽  
Halo Population

AbstractThis is a “biased” review because I will show recent evidence on the contribution of globular clusters (GCs) to the halo of our Galaxy seen through the lens of the new paradigm of multiple populations in GCs. I will show a few examples where the chemistry of multiple populations helps to answer hot questions including whether and how much GCs did contribute to the halo population, if we have evidence of the GCs-halo link, what are the strengths and weak points concerning this contribution.

scholarly journals Stellar Populations in M31 from Broad-band Photometry

2010 ◽  
Vol 6 (S277) ◽  
pp. 199-202
Author(s):  
Antti Tamm ◽  
Elmo Tempel ◽  
Peeter Tenjes ◽  
Taavi Tuvikene
Keyword(s):  
Complex Structure ◽  
Broad Band ◽  
Far Infrared ◽  
Stellar Populations ◽  
Sloan Digital Sky Survey ◽  
Spectral Energy ◽  
3 Dimensional ◽  
Sky Survey ◽  
The Galaxy ◽  
M 31

AbstractDue to its proximity, size, complex structure and high inclination angle, M31 offers an excellent opportunity for studying galactic structures outside the Milky Way and for drawing implications for their cosmological origin. We have studied the stellar populations of M 31 using the Sloan Digital Sky Survey (SDSS) photometry and the Spitzer far-infrared (FIR) mappings of dust. Combining these data, we have constructed a 3-dimensional model of the galaxy, laying constraints on the intrinsic (dust-free) properties of the galaxy and its stellar populations: their apparent and intrinsic luminosities, luminosity distributions, colours, shapes and sizes. We have interpreted the derived spectral energy distributions with synthetic stellar populations created with the Starburst99 software, in order to constrain the ages and masses of the stellar components.

scholarly journals A SURVEY OF CN AND CH VARIATIONS IN GALACTIC GLOBULAR CLUSTERS FROM SLOAN DIGITAL SKY SURVEY SPECTROSCOPY

2011 ◽  
Vol 142 (4) ◽  
pp. 126 ◽  
Author(s):  
Jason P. Smolinski ◽  
Sarah L. Martell ◽  
Timothy C. Beers ◽  
Young Sun Lee
Keyword(s):  
Globular Clusters ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Galactic Globular Clusters

scholarly journals White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14

2019 ◽  
Vol 486 (2) ◽  
pp. 2169-2183 ◽  
Author(s):  
S O Kepler ◽  
Ingrid Pelisoli ◽  
Detlev Koester ◽  
Nicole Reindl ◽  
Stephan Geier ◽  
...  
Keyword(s):  
Survey Data ◽  
White Dwarf ◽  
White Dwarfs ◽  
Main Sequence ◽  
Sloan Digital Sky Survey ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release ◽  
Hot Subdwarfs

ABSTRACT White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs provide insight into the early ages of each population. Examining the spectra of all stars with 3σ proper motion in the Sloan Digital Sky Survey Data Release 14, we report the classification for 20 088 spectroscopically confirmed white dwarfs, plus 415 hot subdwarfs, and 311 cataclysmic variables. We obtain Teff, log  g, and mass for hydrogen atmosphere white dwarf stars (DAs), warm helium atmosphere white dwarfs (DBs), hot subdwarfs (sdBs and sdOs), and estimate photometric Teff for white dwarf stars with continuum spectra (DCs). We find 15 793 sdAs and 447 dCs between the white dwarf cooling sequence and the main sequence, especially below $T_\mathrm{eff}\simeq 10\, 000$ K; most are likely low-mass metal-poor main-sequence stars, but some could be the result of interacting binary evolution.

scholarly journals Gravitational Lensing by Globular Clusters and Arp Objects

2003 ◽  
Vol 214 ◽  
pp. 101-105
Author(s):  
Alexander Yushchenko ◽  
Chulhee Kim ◽  
Alexander Sergeev ◽  
Panos Niarchos ◽  
Vasilis Manimanis
Keyword(s):  
Observational Data ◽  
Gravitational Lensing ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Proper Motions ◽  
Spectroscopic Observations ◽  
Observational Test ◽  
Sky Survey

We try to explain quasar-galaxy associations by gravitational lensing by globular clusters, located in the halos of foreground galaxies. We propose observational test for verification of this hypothesis. We processed SUPERCOSMOS sky survey and found overdensities of star-like sources with zero proper motions in the vicinities of foreground galaxies from CfA3 catalog. We show mean effect for galaxies with different redshifts. Two effects can explain observational data - these are lensing by globular clusters and lensing by dwarf galaxies. We made CCD 3-color photometry with 2.0-1.2 meter telescopes to select extremely lensed objects around several galaxies for spectroscopic observations.

scholarly journals Probing star formation and ISM properties using galaxy disk inclination

2018 ◽  
Vol 615 ◽  
pp. A7 ◽  
Author(s):  
S. K. Leslie ◽  
M. T. Sargent ◽  
E. Schinnerer ◽  
B. Groves ◽  
A. van der Wel ◽  
...  
Keyword(s):  
Sample Selection ◽  
Ultra Violet ◽  
Far Infrared ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Star Forming Regions ◽  
Sky Survey ◽  
Dust Fraction ◽  
Galaxy Disk ◽  
Intermediate Redshift

Disk galaxies at intermediate redshift (z ~ 0.7) have been found in previous work to display more optically thick behaviour than their local counterparts in the rest-frame B-band surface brightness, suggesting an evolution in dust properties over the past ~6 Gyr. We compare the measured luminosities of face-on and edge-on star-forming galaxies at different wavelengths (Ultraviolet (UV), mid-infrared (MIR), far-infrared (FIR), and radio) for two well-matched samples of disk-dominated galaxies: a local Sloan Digital Sky Survey (SDSS)-selected sample at z ~ 0.07 and a sample of disks at z ~ 0.7 drawn from Cosmic Evolution Survey (COSMOS). We have derived correction factors to account for the inclination dependence of the parameters used for sample selection. We find that typical galaxies are transparent at MIR wavelengths at both redshifts, and that the FIR and radio emission is also transparent as expected. However, reduced sensitivity at these wavelengths limits our analysis; we cannot rule out opacity in the FIR or radio. Ultra-violet attenuation has increased between z ~ 0 and z ~ 0.7, with the z ~ 0.7 sample being a factor of ~3.4 more attenuated. The larger UV attenuation at z ~ 0.7 can be explained by more clumpy dust around nascent star-forming regions. There is good agreement between the fitted evolution of the normalisation of the SFRUV versus 1 − cos(i) trend (interpreted as the clumpiness fraction) and the molecular gas fraction/dust fraction evolution of galaxies found out to z < 1.

scholarly journals The kinematics of white dwarfs from the SDSS DR12

2017 ◽  
Vol 13 (S334) ◽  
pp. 294-295
Author(s):  
E. García–Berro ◽  
G. Skorobogatov ◽  
S. Torres ◽  
B. Anguiano ◽  
A. Rebassa-Mansergas
Keyword(s):  
White Dwarfs ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Three Dimensional ◽  
Radial Distance ◽  
Sloan Digital Sky Survey ◽  
Original Sample ◽  
Proper Motions ◽  
Sky Survey ◽  
Data Release

AbstractWe use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalogue to date, to study the evolution of the kinematical properties of the population of white dwarfs of the Galactic disk. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalogue are available, the three-dimensional components of the velocity are obtained. This subset of the original sample comprises 20,247 stars, making it the largest sample of white dwarfs with measured three-dimensional velocities. The volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance RG = 7.8 to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = +0.5 to –0.5 kpc.

scholarly journals Planetary Nebulae, Globular Clusters and the Galactic Halo

1973 ◽  
Vol 21 ◽  
pp. 26-28
Author(s):  
Sidney Van Den Bergh
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Planetary Nebulae ◽  
Halo Population

AbstractPlanetary nebulae are used as a tracer for halo Population II stars. A comparison of the number of planetary nebulae in the galactic pole caps (|b| ≥ 45°) with the number of planetaries in globular clusters suggests that (to within a factor of 2 or 3) the galactic halo has a luminosity LB ⋍ 2 × 108L⊙. From the work of Oort it is estimated that the galactic halo has a mass of at least so that for the galactic halo.

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