SIMBAD references

2011AJ....141...31C - Astron. J., 141, 31 (2011/February-0)

History and modes of star formation in the most active region of the Small Magellanic Cloud, NGC 346.


Abstract (from CDS):

We discuss the star formation history of the Small Magellanic Cloud (SMC) region NGC 346 based on Hubble Space Telescope images. The region contains both field stars and cluster members. Using a classical synthetic color-magnitude diagram (CMD) procedure applied to the field around NGC 346 we find that the star formation pace there has been rising, from a quite low rate 13 Gyr ago to ~1.4x10–8 M/yr/pc2 in the last 100 Myr. This value is significantly higher than that in other star-forming regions of the SMC. For NGC 346 itself, we compare theoretical and observed CMDs of several stellar sub-clusters identified in the region, and we derive their basic evolution parameters. We find that NGC 346 experienced different star formation regimes, including a dominant and focused "high-density mode," with the sub-clusters hosting both pre-main-sequence (PMS) and upper main-sequence (UMS) stars, and a diffuse "low-density mode," as indicated by the presence of low-mass PMS sub-clusters. Quantitatively, the star formation in the oldest sub-clusters started about 6 Myr ago with remarkable synchronization, it continued at a high rate (up to 2x10–5 M/yr/pc2) for about 3 Myr and is now progressing at a lower rate. Interestingly, sub-clusters mainly composed of low-mass PMS stars now seem to experience the first episode of star formation, following multi-seeded spatial patterns, instead of resulting from a coherent trigger. Two speculative scenarios are put forth to explain the deficiency of UMS stars: the first invokes underthreshold conditions of the parent gas and the second speculates that the initial mass function is a function of time, with the youngest sub-clusters not having had sufficient time to form more massive stars.

Abstract Copyright:

Journal keyword(s): galaxies: star clusters: general - Magellanic Clouds - stars: formation - stars: pre-main sequence

Simbad objects: 9

goto Full paper

goto View the reference in ADS

To bookmark this query, right click on this link: simbad:2011AJ....141...31C and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact