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Astron. Astrophys. 344, 848-856 (1999)


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Very young massive stars in the Small Magellanic Cloud, revealed by HST  *

M. Heydari-Malayeri 1, M.R. Rosa  **  2, H. Zinnecker 3, L. Deharveng 4 and V. Charmandaris 1

1 DEMIRM , Observatoire de Paris, 61 Avenue de l'Observatoire, F-75014 Paris, France
2 Space Telescope European Coordinating Facility, European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany
3 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
4 Observatoire de Marseille, 2 Place Le Verrier, F-13248 Marseille Cedex 4, France

Received 1 December 1998 / Accepted 18 January 1999

Abstract

High spatial resolution imaging with the Hubble Space Telescope allowed us to resolve the compact H II region N 81 lying in the Small Magellanic Cloud (SMC). We show the presence of a tight cluster of newborn massive stars embedded in this nebular "blob" of [FORMULA] 10" across. This is the first time the stellar content and internal morphology of such an object is uncovered. These are among the youngest massive stars in this galaxy accessible to direct observations at ultraviolet and optical wavelengths. Six of them are grouped in the core region of [FORMULA] 2" diameter, with a pair of the main exciting stars in the very center separated by only 0".27 or 0.08 pc. The images display violent phenomena such as stellar winds, shocks, ionization fronts, typical of turbulent starburst regions. Since the SMC is the most metal-poor galaxy observable with very high angular resolution, these observations provide important templates for studying star formation in the very distant metal-poor galaxies which populate the early Universe.

Key words: stars: early-type – stars: Wolf-Rayet – ISM: dust, extinction – ISM: H ii regions – ISM: individual objects: N 81 (SMC) – galaxies: Magellanic Clouds

* Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
** Affiliated to the Astrophysics Division, Space Science Department of the European Space Agency.

Send offprint requests to: M. Heydari-Malayeri (heydari@obspm.fr)

© European Southern Observatory (ESO) 1999

Online publication: March 29, 1999

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