Journal Article

The sequence of low- and high-mass star formation in the young stellar cluster IRAS 19343+2026

D. K. Ojha, M. S. N. Kumar, C. J. Davis and J. M. C. Grave

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 407, issue 3, pages 1807-1818
Published in print September 2010 | ISSN: 0035-8711
Published online September 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17018.x
The sequence of low- and high-mass star formation in the young stellar cluster IRAS 19343+2026

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BVRIJHK photometry, Spitzer-GLIMPSE photometry and HK-band spectroscopy were used to study the stellar content of IRAS 19343+2026, a (proto)star/cluster candidate, located close to the Galactic plane. The data suggest that IRAS 19343+2026 is a rich cluster associated with a massive protostar of 7.6 M with an age of ∼105 yr. Three point sources in the vicinity of the far-infrared peak are also found to be early B-type stars. The remaining (predominantly low mass) members of the cluster are best represented by a 1–3 Myr pre-main-sequence (PMS) population. HK-band spectra of two bright and five faint point sources in the cluster confirm that the results obtained from the photometry are good representations of their young stellar object (YSO) nature. Thus, IRAS 19343+2026 is a young cluster with at least four early B-type stars classified as young (104–105 yr), that are surrounded by a somewhat older (1–3 Myr) population of low-mass YSOs. Together, these results argue for a scenario in which low-mass stars form prior to massive stars in a cluster forming environment. We compute the initial mass function (IMF) for this cluster using the K-band luminosity function; the slope of the IMF is shallower than predicted by the Salpeter's mass function. The cluster mass, Mtotal, is estimated to be in the range ∼307 M (from the data completeness limit) to 585 M (extrapolated down to the brown dwarf limit, assuming a certain IMF).

Keywords: stars: formation; stars: massive; H ii regions; infrared: stars; ISM: general

Journal Article.  7339 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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