|
| | | | |
| | | |
| Stat |
Members: 3645
Articles: 2'504'928
Articles rated: 2609
26 April 2024 |
|
| | | | |
|
Article overview
| |
|
|
High-Dispersion Spectroscopy of Luminous, Young Star Clusters: Evidence for Present-Day Formation of Globular Clusters | | Luis C. Ho
; Alexei V. Filippenko
; | | Date: |
5 Jun 1996 | | Subject: | astro-ph | | Affiliation: | Center for Astrophysics) and Alexei V. Filippenko (U.C. Berkeley | | Abstract: | We present evidence that some of the compact, luminous, young star clusters recently discovered through images taken with the Hubble Space Telescope (HST) have masses comparable to those of old Galactic globular clusters. The "super star cluster" in the center of the nearby amorphous galaxy NGC 1705 has been observed with high dispersion at optical wavelengths using the HIRES echelle spectrograph on the Keck 10 m telescope. Numerous weak metal lines arising from the atmospheres of cool supergiants have been detected in the integrated spectrum, permitting a direct measurement of the line-of-sight stellar velocity dispersion through cross-correlation with a template star; the result is $sigma_*$ = 11.4$pm$1.5 kms. Assuming that the system is gravitationally bound and using a cluster size measured from HST images, we apply the virial theorem to obtain the dynamical mass. Its derived mass [(8.2$pm$2.1) x 10$^4$ $M_{odot}$], mass density (2.7 x 10$^4$ $M_{odot}$ pc$^{-3}$), and predicted mass-to-light ratio after aging by 10--15 Gyr [0.6--1.6 ($M/L_V$)$_{odot}$] closely resemble those of the majority of evolved Galactic globular clusters. The central cluster in NGC 1705 appears to be very similar in nature to one of the bright clusters in NGC 1569, which is discussed by Ho Filippenko (1996). We also observed the brightest cluster in the Magellanic irregular galaxy NGC 4214, but no lines suitable for measuring its velocity dispersion were detected, most likely because of the very young age of the cluster. Although these observations need to be extended to a much larger sample of objects before generalizations can be made concerning the nature of similar clusters observed in other galaxies, our preliminary results are tantalizing and strongly suggest that, at least in two cases, we are witnessing globular | | Source: | arXiv, astro-ph/9606031 | | Services: | Forum | Review | PDF | Favorites | |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
|
News, job offers and information for researchers and scientists:
| |
REGISTER