Short-Term Spectral Variability in AB Aurigae: Clues for Activity in Herbig AE Stars. I. The Ultraviolet Lines of MG II and Fe II
Abstract
IUE satellite monitoring of the Herbig Ae star AB Aur in 1982 and 1984, with attention to the variability of both the Mg II 2795 A wind profile and a number of Fe II UV lines, has indicated temporal variations in the Mg II blue wing velocity by 30-50 percent at both epochs. By contrast, the Fe II spectrum was constant in 1982, but variable in 1984. There is no evidence of photometric variability in AB Aur during either period. An analysis of the Mg II blue wing velocity vs time shows that the variability can be fitted with a sine curve of period 45 + or - 6 hours, which is interpreted to be the stellar rotation period. The observed rotational modulation of the blue wing velocity of Mg II 2795 A in AB Aur's wind is the first direct evidence of a nonaxisymmetric wind in an A-type premain sequence object.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1986
- DOI:
- 10.1086/164076
- Bibcode:
- 1986ApJ...303..311P
- Keywords:
-
- A Stars;
- Line Spectra;
- Periodic Variations;
- Pre-Main Sequence Stars;
- Spectral Energy Distribution;
- Stellar Activity;
- Ultraviolet Spectra;
- Iron;
- Iue;
- Magnesium;
- Spaceborne Astronomy;
- Stellar Magnetic Fields;
- Stellar Rotation;
- Stellar Spectrophotometry;
- Stellar Winds;
- Astrophysics;
- STARS: EMISSION-LINE;
- STARS: INDIVIDUAL CONSTELLATION NAME: AB AURIGAE;
- STARS: WINDS;
- ULTRAVIOLET: SPECTRA