Tuesday Lunch 4/8: Paul Green (CfA)

Innocent Bystanders and Smoking Guns: the Dwarf Carbon Stars

Dr. Paul Green (CfA)
CAS 500, 12:30 pm, April 8, 2014

Fellow carbon-based life forms, as far as we know, most carbon throughout the Universe is created and dispersed by (AGB) stars in their final breaths. So it was at first surprising to find that the carbon stars most prevalent in the Galaxy are in fact dwarfs. We suspect that these dC stars are most likely innocent bystanders in post-mass transfer binaries, and may be predominantly metal-poor. As such, they may retain the chemical and orbital imprints of the first stars. Among 1200 C stars found in the SDSS, we confirm 724 dCs, of which a dozen are DA/dC stars in composite spectrum binaries, quadrupling the total sample of these “smoking guns” for AGB binary mass transfer. Whether you think of them as ‘enhanced’ or ‘polluted’ we’ll review the ubiquitous anomaly of C-enriched main sequence stars and several new projects to study them further.