CLUES TO THE STAR FORMATION IN NGC 346 ACROSS TIME AND SPACE

Journal Article · Mon Oct 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/740/1/10; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587435

De Marchi, Guido ^[1]; Panagia, Nino; Sabbi, Elena ^[2]

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1. European Space Agency, Space Science Department, Keplerlaan 1, 2200 AG Noordwijk (Netherlands)
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

We have studied the properties of the stellar populations in the field of the NGC 346 cluster in the Small Magellanic Cloud, using the results of a novel self-consistent method that provides a reliable identification of pre-main sequence (PMS) objects actively undergoing mass accretion, regardless of their age. The 680 identified bona fide PMS stars show a bimodal age distribution, with two roughly equally numerous populations peaked, respectively, at {approx}1 Myr and {approx}20 Myr. We use the age and other physical properties of these PMS stars to study how star formation has proceeded across time and space in NGC 346. We find no correlation between the locations of young and old PMS stars, nor do we find a correspondence between the positions of young PMS stars and those of massive OB stars of similar age. Furthermore, the mass distribution of stars with similar age shows large variations throughout the region. We conclude that, while on a global scale it makes sense to talk about an initial mass function, this concept is not meaningful for individual star-forming regions. An interesting implication of the separation between regions where massive stars and low-mass objects appear to form is that high-mass stars might not be 'perfect' indicators of star formation and hence a large number of low-mass stars formed elsewhere might have so far remained unnoticed. For certain low surface density galaxies this way of preferential low-mass star formation may be the predominant mechanism, with the consequence that their total mass as derived from the luminosity may be severely underestimated and that their evolution is not correctly understood.

• OSTI ID: 21587435
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 740; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CORRELATIONS
DISTRIBUTION
FUNCTIONS
GALAXIES
LUMINOSITY
MAGELLANIC CLOUDS
MASS
MASS DISTRIBUTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPATIAL DISTRIBUTION
STAR CLUSTERS
STARS
VARIATIONS