AAS 197, January 2001
Session 13. Early Science from the Sloan Digital Sky Survey
Display, Monday, January 8, 2001, 9:30am-7:00pm, Exhibit Hall

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[13.09] Needles in a Haystack: Faint Carbon Stars Discovered by the Sloan Digital Sky Survey

B. Margon, S. F. Anderson, B. F. Williams, E. W. Deutsch (U. Washington), H. Harris (USNO), X. Fan, G. R. Knapp, M. A. Strauss, R. H. Lupton (Princeton U.), D. E. Vanden Berk (Fermilab), D. Schneider (PSU)

At magnitudes fainter than 16, carbon stars are less than one in a million stellar images. However, the precision five-color photometry of the Sloan Digital Sky Survey has enabled discovery of more than two dozen such faint high latitude carbon stars (FHLCs) in an informal analysis of commissioning data. The objects range over 16.6 < r' < 20.2, and show a diversity of temperatures as judged by both colors and NaD line strengths. These stars are in general too faint and too warm to be effectively identified in other modern automated surveys such as 2MASS, nor are their IR colors distinctive. We present new proper motion measures for most of the objects, indicating that the sample is in all probability a mixture of extremely distant (>100~kpc) halo stars, plus members of the recently-recognized exotic class of very nearby dwarf carbon (dC) stars. Motions, and thus dC classification, are inferred for 40-50% of the sample, depending on the level of statistical significance invoked. The SDSS spectra also suggest the presence of a long-awaited low-resolution spectroscopic luminosity discriminant between dC's and distant luminous giants. The implied surface density of FHLCs in this magnitude range is uncertain due to completeness corrections, but is at least 0.04~deg2, significantly higher than previous reports, but consistent with the fainter limits of our technique, and the somewhat different intrinsic properties of our sample. At the completion of the Sloan Survey, there will be many hundred homogeneously selected and observed FHLCs in this sample.

The author(s) of this abstract have provided an email address for comments about the abstract: margon@astro.washington.edu

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