THE CARBON MIRA UV AURIGAE AND ITS COMPANION
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
The carbon Mira UV Aur (photometric period 394 days) and its companion present several interesting spectroscopic issues. The late B-type companion, at a separation of 3.''36, is seen through at least two shells expanding from the C9-type primary, as evidenced by a series of narrow, displaced absorption features at the D{sub 1,2} lines of Na I. The (projected) expansion velocity of the fastest shell is about 116 km s{sup -1}, much larger than the typical outflow velocity of about 15 km s{sup -1} seen in C-type giants, but reminiscent of the velocities observed in the envelope of another C-type Mira, V Hya. Emission lines of H, Ca II, and Na I are present in UV Aur A; its Balmer emission lines are heavily mutilated by overlying C-type absorptions (much as is seen in Me-type Miras), so they must be formed at a lower level. UV Aur B offers the opportunity to test a speculation that the carriers of the diffuse interstellar bands (DIBs), believed to be a family of carbon-containing polyatomic molecules, may be formed in cool, carbon-rich stars. Moderately strong DIBs are indeed present in the spectrum of UV Aur B at about the same strength and velocity seen in nearby (in the sky) B-type stars. But the essential question is, are DIBs present in the outflow from UV Aur A, at the velocities of the Na I shell components? The answer is no, at least at the level permitted by the signal-to-noise ratio of these Keck/HIRES spectrograms.
- OSTI ID:
- 21301542
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 138, Issue 5; Other Information: DOI: 10.1088/0004-6256/138/5/1502; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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