SDSS absolute magnitudes for thin-disc stars based on trigonometric parallaxes |
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| Authors: | S Bilir S Karaali S Ak K B Co&#;kuno&#;lu E Yaz A Cabrera-Lavers |
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| Institution: | Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey;Beykent University, Faculty of Science and Letters, Department of Mathematics and Computer, Beykent 34398, Istanbul, Turkey;Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain;GTC Project Office, E-38205 La Laguna, Tenerife, Spain |
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| Abstract: | We present a new luminosity–colour relation based on trigonometric parallaxes for thin-disc main-sequence stars in Sloan Digital Sky Survey (SDSS) photometry. We matched stars from the newly reduced Hipparcos catalogue with the ones taken from Two-Micron All-Sky Survey (2MASS) All-Sky Catalogue of Point Sources, and applied a series of constraints, i.e. relative parallax errors (σπ/π≤ 0.05) , metallicity (?0.30 ≤M/H]≤ 0.20 dex) , age (0 ≤ t ≤ 10 Gyr) and surface gravity (log g > 4) , and obtained a sample of thin-disc main-sequence stars. Then, we used our previous transformation equations ( Bilir et al. 2008a ) between SDSS and 2MASS photometries and calibrated the Mg absolute magnitudes to the ( g ? r )0 and ( r ? i )0 colours. The transformation formulae between 2MASS and SDSS photometries along with the absolute magnitude calibration provide space densities for bright stars which saturate the SDSS magnitudes. |
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| Keywords: | stars: distances Galaxy: disc solar neighbourhood |
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