The Discovery of Two Nearby Carbon Dwarfs

The comparison of optical and Two Micron All Sky Survey near-infrared photometry for large samples of cataloged proper-motion stars has given us the potential to discover previously unrecognized nearby objects of rare type. In this Letter we present the discovery of two new carbon dwarfs, LSR 2105+2514 and LP 758-43, which were drawn from proper-motion lists and which lie in a sparsely populated part of optical/near-IR color-color space. Their optical spectra, exhibiting absorptions by C₂ and/or CN, are discussed. LSR 2105+2514 is believed to lie within 200 pc and would have M_Ks>=6.7, making it lower in luminosity than any carbon dwarf with a measured trigonometric parallax. LP 758-43, which is not as red but still probably cooler than the best studied carbon dwarfs, is believed to lie within 360 pc. Using our optical/near-infrared selection technique on published lists of proper-motion stars, we hope in the near future to expand further the current sample of carbon dwarfs, which numbers only 31 objects at this writing.