EDP Sciences
Free access
Volume 408, Number 3, September IV 2003
Page(s) L13 - L16
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20031148

A&A 408, L13-L16 (2003)
DOI: 10.1051/0004-6361:20031148


A molecular gas bridge between the Taffy galaxies

J. Braine1, E. Davoust2, M. Zhu3, U. Lisenfeld4, C. Motch5 and E. R. Seaquist3

1  Observatoire de Bordeaux, UMR 5804, CNRS/INSU, BP 89, 33270 Floirac, France
2  UMR 5572, Observatoire Midi-Pyrénées, 11 avenue Édouard Belin, 31400 Toulouse, France
3  Univ. of Toronto, Dept. of Astronomy & Astrophysics, 60 Saint George St., Toronto ON M5S 3H8, Canada
4  Instituto de Astrofísica de Andalucía, CSIC, Apdo. Correos 3004, 18080 Granada, Spain
5  Observatoire de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France

(Received 5 May 2003 / Accepted 28 July 2003 )

The Taffy Galaxies system, UGC 12914/5, contains huge amounts of molecular gas in the bridge region between the receding spirals after a direct collision. $2{-}9 \times 10^9$  $M_\odot$ of molecular gas is present between the galaxies, more than the CO emission from the entire Milky Way! Such dense gas can only be torn off by collisions between dense clouds, in this case with relative velocities of about 800 ${\rm\, km \, s^{-1}}$, such that the remnant cloud acquires an intermediate velocity and is left in the bridge after separation of the colliding galaxies. We suggest that after ionization in the collision front, the gas cooled and recombined very quickly such that the density remained high and the gas left the colliding disks in molecular form.

Key words: galaxies: spiral -- galaxies: evolution -- galaxies: ISM -- galaxies: interaction -- galaxies: individual: UGC 12914 -- galaxies: individual: UGC 12915

Offprint request: J. Braine, braine@obs.u-bordeaux1.fr

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