Preliminary trigonometric parallaxes and BVI photometry are presented for two dwarf carbon stars , LP765 - 18 ( = LHS1075 ) and LP328 - 57 ( = CLS96 ) .
The data are combined with the literature values for a third dwarf carbon star , G77 - 61 ( = LHS1555 ) .
All three stars have very similar luminosities ( 9.6 < M _ { V } < 10.0 ) and very similar broadband colors across the entire visual-to-near IR ( BVIJHK ) wavelength range .
Their visual ( BVI ) colors differ from all known red dwarfs , subdwarfs , and white dwarfs .
In the M _ { V } versus V - I color–magnitude diagram they are approximately 2 magnitudes subluminous compared with normal disk dwarfs with solar-like metallicities , occupying a region also populated by O-rich subdwarfs with -1.5 < [ m/H ] < -1.0 .
The kinematics indicate that they are members of the Galactic spheroid population .
The subluminosity of all three stars is due to an as-yet-unknown combination of ( undoubtedly low ) metallicity , possibly enhanced helium abundance , and unusual line-blanketing in the bandpasses considered .
The properties of the stars are compared with models for the production of dwarf carbon stars .