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J. Schroeder, G.R. Knapp (Princeton), B. Margon (STScI), D.J. Schlegel, M.A. Strauss (Princeton), C. Tremonti (JHU), H. Harris (USNO), J. Liebert, D. Eisenstein (Arizona), J.E. Gunn, E. Sirko, R.H. Lupton, Z. Ivezic (Princeton), S. Anderson, C.M. Rockosi (U. Washington), R. Downes (STScI), D.P. Schneider (Penn State), T.A. McKay (Michigan), SDSS Collaboration
SDSS spectroscopy of some 8000 high-latitude main-sequence-turnoff stars between magnitudes r* = 15-18.5 finds that 20 show the Swan bands of \rm C2, as well as anomalously strong CH bands. Three further members of this class are found in other SDSS spectroscopy. The ``underlying'' spectra are dominated by strong Balmer and CaII absorption, corresponding to late F/G spectral type. The spectra resemble those of the giant and subgiant CH stars, but the proper motion information suggests that many are main-sequence stars. The effective temperatures (as estimated from SDSS and 2MASS photometry) fall in the range 5000 K to 6400 K, while the strengths of the CaII lines and the radial velocities suggest that most of these are metal-poor halo stars. The discovery of these objects shows that stars with C/O > 1 extend all the way along the old main sequence, and measures the fraction of the halo main sequence stars which are carbon stars to be 0.2%.
Funding for the SDSS is provided by the Alfred P. Sloan Foundation, NASA, NSF, DoE, Monbukagakusho, the Max Planck Society and the member institutions. The SDSS web site is http://www.sdss.org/.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.