Evidence for halo kinematics among cool carbon-rich dwarfs
| Autor: | Jay Farihi, L J Whitehouse, A R Arendt, H S Machado |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Physics
education.field_of_study Proper motion Stellar mass Population FOS: Physical sciences White dwarf Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrometry Astrophysics 01 natural sciences Galaxy Galactic halo Stars Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010306 general physics education 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 477:3801-3806 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | This paper reports preliminary yet compelling kinematical inferences for N ~ 600 carbon-rich dwarf stars that demonstrate around 30% to 60% are members of the Galactic halo. The study uses a spectroscopically and non-kinematically selected sample of stars from the SDSS, and cross-correlates these data with three proper motion catalogs based on Gaia DR1 astrometry to generate estimates of their 3-D space velocities. The fraction of stars with halo-like kinematics is roughly 30% for distances based on a limited number of parallax measurements, with the remainder dominated by the thick disk, but close to 60% of the sample lie below an old, metal-poor disk isochrone in reduced proper motion. An ancient population is consistent with an extrinsic origin for C/O >1 in cool dwarfs, where a fixed mass of carbon pollution more readily surmounts lower oxygen abundances, and with a lack of detectable ultraviolet-blue flux from younger white dwarf companions. For an initial stellar mass function that favors low-mass stars as in the Galactic disk, the dC stars are likely to be the dominant source of carbon-enhanced, metal-poor stars in the Galaxy. 7 pages, 1 table, and 3 figures. Accepted to MNRAS |
| Databáze: | OpenAIRE |
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