IUE observations of UV carbon I absorption lines in the spectrum of the C2 white dwarf L 97-3.

Abstract

Extremely strong absorption features have been detected in the short wavelength UV spectrum of a cool helium-rich white dwarf, L 97-3, classified C₂ weak from faint Swan band absorption in the visible. The spectrum shows the signature of neutral carbon, whose resonance lines as well as at least 4 additional lines are identified. The carbon abundance appears to be rather low with He/C ≈ 10⁷. Strong asymmetries appear below λ1930 and λ1657 Å. It is the first time that transitions from the lowest levels of neutral carbon have been found in a stellar spectrum.