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Astron. Astrophys. 331, 857-872 (1998)


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Results of the SEST key programme: CO in the Magellanic Clouds

VII. 30 Doradus and its southern H II regions *

L.E.B. Johansson 1, A. Greve 2, R.S. Booth 1, F. Boulanger 3, 4, G. Garay 5, Th. de Graauw 6, F.P. Israel 7, M.L. Kutner 8, 9, J. Lequeux 3, 10, D.C. Murphy 11, L.-Å. Nyman 12 and M. Rubio 5

1 Onsala Space Observatory, S-439 92 Onsala, Sweden
2 IRAM, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d'Heres, France
3 Radioastronomie, Ecole Normale Superieure, 24 rue Lhomond, F-75231 Paris CEDEX 05, France
4 Institut d'Astrophysique Spatiale, Bat. 120, Université de Paris-XI, F-91045 Orsay CEDEX, France
5 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
6 Laboratorium voor Ruimteonderzoek, SRON, Postbus 800, 9700 AV Groningen,The Netherlands
7 Sterrewacht, Postbus 9513, 2300 RA Leiden, The Netherlands
8 NRAO, 949 N. Cherry Av., Campus Building 65, Tucson, AZ 85721-0655, USA
9 Department of Physics, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
10 DEMIRM, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris, France
11 The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101, USA
12 European Southern Observatory, Casilla 19001, Santiago 19, Chile

Received 4 August 1997 / Accepted 20 November 1997

Abstract

We have mapped the 12 CO(1-0) emission from the 30 Doradus region in the Large Magellanic Cloud with the Swedish-ESO Submillimetre Telescope (SEST). The regions investigated include the central part of the 30 Dor nebula, and the southern H II regions N 158C, N 159, and N 160. In addition, a few prominent CO clouds have been studied in the (2-1) and (3-2) transitions of CO.

The southern area shows the strongest 12 CO(1-0) emission, a factor of 3 higher than towards the central part of 30 Dor. A non-LTE analysis of the CO emission from a sample of clouds indicate kinetic temperatures between 10 and 50 K; the highest temperatures are found close to the 30 Dor nebula. We have estimated the CO-H2 conversion factor for the two areas, separately, under the assumption that the virial mass, determined from CO parameters, reflects the total molecular mass. We find an unexpectedly small difference between the two areas. This is explained as a bias effect.

Key words: galaxies: individual: LMC – Magellanic Clouds – galaxies: ISM – galaxies: irregular – ISM: molecules – ISM: clouds

* Based on results collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: L.E.B. Johansson

© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998
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