New observations of extra-disk molecular gas in interacting galaxy systems, including a two-component system in Stephanis Quintet

Citation
Bj. Smith et C. Struck, New observations of extra-disk molecular gas in interacting galaxy systems, including a two-component system in Stephanis Quintet, ASTRONOM J, 121(2), 2001, pp. 710-726
Citations number
84
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMICAL JOURNAL
ISSN journal
0004-6256 → ACNP
Volume
121
Issue
2
Year of publication
2001
Pages
710 - 726
Database
ISI
SICI code
0004-6256(200102)121:2<710:NOOEMG>2.0.ZU;2-R
Abstract
We present new CO (1-0) observations of 11 extragalactic tails and bridges in nine interacting galaxy systems, almost doubling the number of such feat ures with sensitive CO measurements. Eight of these 11 features were undete cted in CO to very low CO/H I limits, with the most extreme case being the NGC 7714/5 bridge. This bridge contains luminous H II regions and has a ver y high H I column density (1.6 x 10(21) cm(-2) in the 55" CO beam), yet was undetected in CO to rms T-R(*) = 2.4 mK. The H I column density is higher than standard and CO self-shielding limits for solar-metallicity gas, sugge sting that the gas in this bridge is metal-poor and has an enhanced N-H2/I- CO ratio compared with the Galactic value. Only one of the 11 features in o ur sample was unambiguously detected in CO, a luminous H I-rich star format ion region near an optical tail in the compact group Stephan's Quintet. We detect CO at two widely separated velocities in this feature, at similar to 6000 and similar to 6700 km s(-1). Both of these components have H I and H a counterparts. These velocities correspond to those of galaxies in the gro up, suggesting that this gas is material that has been removed from two gal axies in the group. The CO/H I/H alpha ratios for both components are simil ar to global values for spiral galaxies.