Proceedings of the
Workshop
"
The Magellanic Clouds and Other Dwarf Galaxies"
of the
Bonn/Bochum-Graduiertenkolleg
ROSAT observations of the giant
H II complex N 11 in the LMC
Sean D. Points2, R. Chris Smith3,
and Bart P. Wakker4
1Max-Planck-Institut für
Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
2Dept. of Astronomy, Univ.
of Illinois, 1002 W. Green St., Urbana, IL 61801, USA
3Dept. of Astronomy,
Univ. of Michigan, 934 Dennison Bldg., Ann Arbor, MI 48109, USA
4Dept. of Astronomy, Univ.
of Wisconsin, 475 N. Charter Street, Madison, WI 53706, USA
Received 15th March 1998
The giant H II complex N 11 in the Large Magellanic
Cloud (Henize 1956) contains OB associations at several different stages in
their life histories (Lucke & Hodge 1970; Parker et al. 1992, 1996).
We have obtained
ROSAT
PSPC and HRI X-ray observations, CTIO
Curtis Schmidt CCD images, CTIO
4 m echelle spectra in Halpha and
[N II] lines, and
IUE
interstellar absorption line observations of this region.
Figure 1 shows the X-ray and
Halpha images. Quantitative
results
and the calibration of the data are described in Mac Low et al. (1998).
We find that the central bubble of N 11 has an X-ray luminosity a factor
of only 3-7 brighter than predicted for an energy-conserving superbubble
(Chu & Mac Low 1990; Chu et al. 1995), making this the first detection of
X-ray emission from a superbubble without a strong X-ray excess.
The region N 11 B contains an extremely young OB association analogous
to the central association of the Carina nebula, apparently still embedded
in its natal molecular cloud (Caldwell 1996, 1997; Israel & De Graauw 1991).
N 11 B emits diffuse X-ray emission, probably powered by stellar
winds.
Finally, we compare the tight cluster HD 32228 in N 11 to R136 in
30 Dor.
The latter is a strong X-ray source (Wang & Helfand 1991), while the former
is not detected, showing that strong X-ray emission from compact objects
(Wang 1995) is not a universal property of such tight clusters.
[Click here to see Fig. 1!]
Acknowledgments.
We thank G. García-Segura for participation in early stages of this
project.
SDP acknowledges the hospitality of the Max-Planck-Institut für Astronomie,
and support from a National Science Foundation Graduate Fellowship.
This research was partially supported by NASA grants NAG5-2245 and NAG5-1900.
References
- Caldwell D. A., 1996, Bull. Amer. Astron. Soc. 28, 953
- Caldwell D. A., 1997, PhD Thesis, Rensselaer Polytechnic Institute
- Chu Y.-H., Chang H., Su Y., Mac Low M.-M., 1995, ApJ 450, 157
- Chu Y.-H., Mac Low M.-M., 1990, ApJ 365, 510
- Henize K. G., 1956, ApJS 2, 315
- Israel F.P., de Graauw Th., 1991, in 'The Magellanic Clouds', Haynes R.,
Milne D. (eds.), p. 45
- Lucke P.B., Hodge P.W., 1970, AJ 75, 171
- Mac Low M.-M., Chang T.H., Chu Y.-H., Points S.D., Smith R.C., Wakker B.P.,
1998, ApJ 493, 260
- Parker J.Wm., Garmany C.D., Massey P., Walborn N.R., 1992, AJ 103, 1205
- Parker J.Wm., Hill J.K., Bohlin R.C., O'Connell R.W., Neff S.G.,
Roberts M.S., Smith A.M., Stecher T.P., 1996, ApJ 472, L29
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- Wang Q., Helfand D.J., 1991, ApJ 370, 541
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| First version: | 09th | August, | 1998
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| Last update: | 30th | September, | 1998
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Jochen M. Braun &
Tom Richtler
(E-Mail: jbraun|richtler@astro.uni-bonn.de)