Spectroscopy of Massive Stars in NGC 6822 and M33

ABSTRACT We present blue spectra of massive stars in the Local Group galaxies NGC 6822 and M33. For all the targets, selected from our previousHubble Space TelescopeWFPC2 photometry, no previous spectroscopic studies exist, to our knowledge, except for a bright Wolf‐Rayet star in NGC 6822. Photosp... Ausführliche Beschreibung

1. Person: Bianchi, Luciana
Weitere Personen: Catanzaro, Giovanni verfasserin; Scuderi, Salvatore verfasserin; Hutchings, John B. verfasserin
Quelle: in Publications of the Astronomical Society of the Pacific : electronic edition Vol. 113, No. 784 (2001), p. 697-702
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Format: Online-Artikel
Sprache: English
Veröffentlicht: 2001
Beschreibung: Online-Ressource
Schlagworte: research-article
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Anmerkung: 1 Center for Astrophysical Sciences, Johns Hopkins University, 239 Bloomberg Center, 3400 North Charles Street, Baltimore, MD 21218‐2695; bianchi@pha.jhu.edu . 2 Also at Osservatorio Astronomico di Torino, Italy. 3 Observer with the Canada‐France‐Hawaii Telescope, which is operated by the NRC of Canada, CNRS of France, and the University of Hawaii. 4 Osservatorio Astrofisico di Catania, Italy. 5 Dominion Astrophysical Observatory, NRC of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada.
Copyright: © 2001. The American Astronomical Society. All rights reserved. Printed in U.S.A.
Zusammenfassung: ABSTRACT We present blue spectra of massive stars in the Local Group galaxies NGC 6822 and M33. For all the targets, selected from our previousHubble Space TelescopeWFPC2 photometry, no previous spectroscopic studies exist, to our knowledge, except for a bright Wolf‐Rayet star in NGC 6822. Photospheric parametersT effand gravity are derived by a model fit of the Balmer lines and multiband (UV to optical) photometry combined and are compared with evolutionary models. Inferred masses range from ≈7 to ≈40 $M_{\odot }$ in the sample. From the spectroscopy, we classify the Wolf‐Rayet star in NGC 6822 as WN3(‐4), with no hydrogen. We estimate its progenitor mass of ≈ $40\pm 10$ $M_{\odot }$ . For two stars in the NGC 6822 sample, our data are not sufficient to establish whether they are foreground stars toward NGC 6822 or they belong to the galaxy.
ISSN: 1538-3873

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