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Candidate subdwarfs and white dwarfs from the 2MASS, Tycho-2, XPM and UCAC3 catalogues
- Source :
- Monthly Notices of the Royal Astronomical Society. 413:1581-1599
- Publication Year :
- 2011
- Publisher :
- Oxford University Press (OUP), 2011.
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Abstract
- The photometry from 2MASS, UCAC3 and SuperCosmos catalogues together with the proper motions from the Tycho-2, XPM and UCAC3 catalogues are used to select the all-sky samples of 34 white dwarfs, 1996 evolved and 7769 unevolved subdwarfs candidates for R from 9 to 17 magnitude. The samples are separated from the main sequence with admixture less than 10% owing to the detailed analysis of the distribution of the stars in the different color index (CI) vs. reduced proper motion (RPM) diagrams for various latitudes with special attention to the estimation of admixtures in the samples and with Monte-Carlo simulation. It is shown that the XPM and UCAC3 have the same level of proper motion accuracy. Most of the selected stars has at least 6-band photometry with accuracy is proved to be better than 0.2. The multicolor photometry allows us to eliminate some admixtures and reveal some binaries. The empirical calibrations of absolute magnitude versus CI and RPM for Hipparcos stars give us photometric distances and 3D distribution for all the stars. Although the selection method and uneven distribution of the XPM and UCAC3 data provide noticeable biases the preliminary conclusions are made. The subdwarfs show some concentration to the galactic centre hemisphere with voids because of extinction in the Gould belt and galactic plane. Some yet unexplained overdensities of the evolved subdwarfs are seen in several parts of the sky. For 183 stars with radial velocities 3D motion and galactic orbits are calculated. For 56 stars with Fe/H collected from various sources we find the relations of the metallicity with CI, asymmetric drift velocity and orbital eccentricity. It is shown that most unevolved subdwarfs belong to the halo with
Details
- ISSN :
- 00358711
- Volume :
- 413
- Database :
- OpenAIRE
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Accession number :
- edsair.doi...........ecea3956942ec91693e7dbf649d619d0