NOAO >   Observing Info >   Approved Programs >   2014A-0090

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Proposal Information for 2014A-0090


PI: Jay Farihi, University of Cambridge, jfarihi@ast.cam.ac.uk
Address: Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

CoI: Hugh Harris, US Naval Observatory Flagstaff
CoI: Carolina Bergfors, University of Cambridge
CoI: Paul Green, Harvard-Smithsonian Center for Astrophysics
CoI: Boris Gansicke, University of Warwick

Title: Are All Dwarf Carbon Stars Binary?

Abstract: The origin of dwarf carbon stars is a persistent astrophysical curiosity dating back to 1977. Only giant stars dredge up interior carbon, and hence the discovery of an unevolved dwarf star with C/O >1 was a big surprise. Astronomers are no closer to understanding these rare and spectrally peculiar stars 35 years later(!). The bulk of dwarf carbon stars show no sign of an evolved companion necessary to account for their externally polluted atmospheres. These stars are sensitive tracers of Galactic chemical evolution and star formation, and provide strong constraints on the potential for carbon-dominated (single star) planetary systems. We propose to conclusively validate or refute the hypothetical binary nature of dwarf carbon stars, and hence their chemical and physical formation channel(s). For all binaries, we will initially constrain and eventually measure orbital periods. By determining their physical separation during the previous epoch of mass transfer, we will distinguish between the Roche lobe overflow and wind capture models for the creation of carbon dwarfs.


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NOAO >   Observing Info >   Approved Programs >   2014A-0090

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