2002/08/28 by U. Lisenfeld, Ute Lisenfeld, Jonathan Braine +9 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Atomic carbon #Carbon monoxide #Dwarf galaxy #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hydrogen molecule #Intergalactic travel #Molecular cloud #Star formation #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021232
published as Astron.Astrophys. 394 (2002) 823-834 · 12 pages, accepted by A&A, version with full resolution images available at http://www.iaa.es/~ute/sq_final.ps
arxiv created 2002/08/28 · openalex publication_date 2002/10/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Stephan's Quintet (SQ) is a system consisting of at least four interacting galaxies which is well known for its complex dynamical and star formation history. It possesses a rich intergalactic medium (IGM), where hydrogen clouds, both atomic and molecular, associated with two starbursts (refered to as SQ A and B) have been found. In order to study the extent, origin and fate of the intergalactic molecular gas and its relation to the formation of stars outside galaxies and Tidal Dwarf Galaxies (TDGs), we mapped with the IRAM 30 m antenna the carbon monoxide (CO) towards several regions of the IGM in SQ. In both SQ A and B, we detected unusually large amounts of molecular gas ( and , respectively). In contrast, no significant CO detection was achieved towards HII regions south of the pair NGC 7318a/b despite their high Hα luminosities. The molecular gas is very extended in both SQ A and SQ B, over areas of between 15 and 25 kpc. The CO clouds seem to have otherwise different properties and may be of a different nature. The integrated CO line of SQ A is in particular much wider than in SQ B. Its CO spectrum shows emission at two velocities (6000 and 6700 km s-1) that are coincident with two HI lines. The strongest emission at 6000 km s-1 is however spatially offset from the HI emission and situated on a ridge south-east of the starburst region. In SQ B the CO emission coincides with that of tracers of star formation (Hα, 15 μm and radio continuum). The CO peak lies slightly offset from the HI peak towards a steep HI gradient. This is indicating that the molecular gas is forming in-situ, possibly in a region of compressed HI, with subsequent star formation. The star forming region at SQ B is the object in SQ that most resembles a TDG.