Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-03-30
Astronomy and Astrophysics
Astrophysics
27 pages, incl. 9 figures, submitted to The Astronomical Journal
Scientific paper
10.1086/300985
We have used the NASA Infra-Red Telescope Facility (IRTF) to observe the nuclear stellar cluster in the nearby, face-on, giant Scd spiral IC 342. From high resolution (R = 21500) spectra at the 12CO (2-0) bandhead at 2.3 micron we derive a line-of-sight stellar velocity dispersion sigma = (33 +- 3) km/s. To interpret this observation we construct dynamical models based on the Jeans equation for a spherical system. The light distribution of the cluster is modeled using an isophotal analysis of an HST V-band image from the HST Data Archive, combined with new ground-based K-band imaging. Under the assumption of an isotropic velocity distribution, the observed kinematics imply a K-band mass-to-light ratio M/L_K = 0.05, and a cluster mass M ~ 6 times 10^6 Msun. We model the mass-to-light ratio with the `starburst99' stellar population synthesis models of Leitherer and collaborators, and infer a best-fitting cluster age in the range 63-630 Myears. Although this result depends somewhat on a number of uncertainties in the modeling (e.g., the assumed extinction along the line-of-sight towards the nucleus, the IMF of the stellar population model, and the velocity dispersion anisotropy of the cluster), none of these can be plausibly modified to yield a significantly larger age. We discuss the implications of this result on possible scenarios for the frequency of nuclear starbursts and their impact on secular evolution of spiral galaxy nuclei. As a byproduct of our analysis, we infer that IC 342 cannot have any central black hole more massive than 0.5 million solar masses. This is ~ 6 times less massive than the black hole inferred to exist in our Galaxy, consistent with the accumulating evidence that galaxies with less massive bulges harbor less massive black holes.
Boeker Torsten
Vacca William D.
van der Marel Roeland P.
No associations
LandOfFree
CO-bandhead spectroscopy of IC 342: mass and age of the nuclear star cluster does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with CO-bandhead spectroscopy of IC 342: mass and age of the nuclear star cluster, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and CO-bandhead spectroscopy of IC 342: mass and age of the nuclear star cluster will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-660395