Astron. Astrophys. 325, 1157-1162
Available formats: HTML |
Two ring nebulae around blue supergiants
in the Large Magellanic Cloud
K. Weis1,2,*, Y.-H. Chu2,*, W.J. Duschl1,3, and D.J. Bomans2,*,**
1Institut für Theoretische Astrophysik, Tiergartenstr. 15, D-69121
2University of Illinois, Department of Astronomy, 1002 W. Green Street,
Urbana, IL 61801, USA
3Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn,
Received 4 March 1997 / Accepted 28 April 1997
Ring nebulae are often found around massive stars such as
Wolf-Rayet stars, OB and Of stars and Luminous Blue Variables (LBVs).
In this paper we report on two ring nebulae around blue supergiants
in the Large Magellanic Cloud. The star Sk-69 279 is classified as
O9f and is surrounded by a closed shell with a diameter of 4.5 pc.
Our echelle observations show an expansion velocity of 14 km s-1 and a
high [NII] 6583Å/H ratio.
This line ratio suggests nitrogen abundance enhancement
consistent with those seen in ejectas from LBVs.
Thus the ring nebula around Sk-69 279 is a circumstellar bubble.
The star Sk-69 271, a B2 supergiant, is surrounded by an H
arc resembling an half shell.
Echelle observations show a large expanding shell
with the arc being part of the approaching surface.
The expansion velocity is ~ 24 km s-1 and the
[NII] 6583Å/H is not much higher than that of the
The lack of nitrogen abundance anomaly suggests that the expanding shell
is an interstellar bubble with a dynamic age of 2 105 yr.
Key words: stars: circumstellar matter -
stars: individual: Sk-69 271 - stars: individual:
Sk-69 279 - stars: mass-loss - ISM: bubbles - Magellanic Clouds
*Visiting Astronomer, Cerro Tololo
Inter-American Observatory, National Optical Astronomy Observatories,
operated by the Association of Universities for Research in Astronomy, Inc.,
under contract with the National Science Foundation.
**Feodor-Lynen Fellow of the
Alexander von Humboldt Foundation
Send offprint requests to: K. Weis
© European Southern Observatory (ESO) 1997
Online publication: September 9, 1997
Last change: April 28, 1998