Astronomers Discover Stars With Carbon Atmospheres. Released at November 21, 2007 P. Dufour, J. Liebert, G. Fontaine, N. Behara published the results in the Nov. 22 issue of Nature. Introduction. Normal white dwarf : the DAs and the non-DAs. George P. McCook and Edward M. Sion,
Astronomers Discover Stars With Carbon Atmospheres
Released at November 21, 2007
P. Dufour, J. Liebert, G. Fontaine, N. Behara
published the resultsin the Nov. 22 issue of Nature
George P. McCook and Edward M. Sion,
The Astrophysical Journal Supplement Series 121, #1 (March 1999), pp. 1–130.
- carbon maximum contamination at Teff~10, 000 K
because of convection
- atmosphere behavior of the hot side had not been
- the discovery of several new hot white dwarfs
with carbon lines in the Sloan Digital Sky Survey
(Liebert et al. 2003)
Fit to the optical spectra (left panel) and energy distribution (right panel) for carbon-rich white dwarfs with log g fixed at 8. Hydrogen and helium abundances are constrained (or dermined in two cases) from the absence of the H(4861) and HeI 4471 lines.
Photometric distances, based on the assumption that log g = 8, are indicated
in each panel.
Artists' concept of the surface of the white dwarf star H1504+65, believed to have somehow expelled all its hydrogen and all but a very small trace of its helium, leaving an essentially bare stellar nucleus with a surface of 50 percent oxygen and 50 percent carbon. When this star cools, it may have a carbon atmosphere.