K-band Spectroscopy of Clusters in NGC 4038/4039
ArXiv astro-ph/0010238 (2000)
Authors:
Sabine Mengel, Matthew D Lehnert, Niranjan Thatte, Lowell E Tacconi-Garman, Reinhard Genzel
Abstract:
Integral field spectroscopy in the K-band (1.9-2.4um) was performed on four
IR-bright star clusters and the two nuclei in NGC 4038/4039 (``The Antennae'').
Two of the clusters are located in the overlap region of the two galaxies, and
together comprise ~25% of the total 15um and ~10% of the total 4.8 GHz emission
from this pair of merging galaxies. The other two clusters, each of them
spatially resolved into two components, are located in the northern galaxy, one
in the western and one in the eastern loop of blue clusters. Comparing our
analysis of Brgamma, CO band-heads, He I (2.058um), Halpha (from archival HST
data), and V-K colors with stellar population synthesis models indicates that
the clusters are extincted (A_V ~ 0.7 - 4.3 mags) and young, displaying a
significant age spread (4-13 Myrs). The starbursts in the nuclei are much older
(65 Myrs), with the nucleus of NGC 4038 displaying a region of recent star
formation northward of its K-band peak. Using our derived age estimates and
assuming the parameters of the IMF (Salpeter slope, upper mass cut-off of 100
M_sun, Miller-Scalo between 1 M_sun and 0.1 M_sun), we find that the clusters
have masses between 0.5 and 5 * 10^6M_sun.
