A Young Super Star Cluster in the Nuclear Region of NGC 253
Abstract
We present observations of a massive star cluster near the nuclear region of the nearby starburst galaxy NGC 253. The peak of near-infrared (IR) emission, which is spatially separated by 4'' from the kinematic center of the galaxy, is coincident with a super star cluster whose properties we examine with low-resolution (R ~ 1200) infrared Cerro Tololo Inter-American Observatory spectroscopy and optical/near-IR Hubble Space Telescope imaging. Extinction, measured from Fe II lines, is estimated at AV = 17.7 ± 2.6. The age of the cluster is estimated at 5.7 Myr, based on Brγ equivalent width for an instantaneous burst using Starburst99 modeling. However, a complex star formation history is inferred from the presence of both recombination emission and photospheric CO absorption. The ionizing photon flux has a lower limit of 7.3 ± 2.5 × 1053 s-1, corrected for extinction. Assuming a Kroupa initial mass function, we estimate a cluster mass of ~1.4+0.4 -0.5 × 107 M sun. We observe a strong Wolf-Rayet signature at 2.06 μm and report a weak feature at 2.19 μm which may be due to a massive stellar population, consistent with the derived mass and age of this cluster.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2009
- DOI:
- 10.1088/0004-637X/697/2/1180
- arXiv:
- arXiv:0902.4027
- Bibcode:
- 2009ApJ...697.1180K
- Keywords:
-
- galaxies: individual: NGC 253;
- galaxies: star clusters;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 8 pages, 5 figures, accepted for publication in ApJ