A&A 407, 913-917 (2003)
Applicability of a Schmidt law to star formation in ring galaxiesE. I. Vorobyov
Institute of Physics, Stachki 194, Rostov-on-Don, Russia, and Isaac Newton Institute of Chile, Rostov-on-Don Branch, Russia
(Received 26 March 2003 / Accepted 19 June 2003)
The gas hydrodynamics modeling of the Cartwheel ring galaxy is performed with the purpose to reproduce the measured intensity and radial distribution of emission in the Cartwheel's disk. The star formation efficiency of is derived for an assumed Schmidt law with power index N=1.5 and a full thickness of the Cartwheel's gas disk of z0=250-1000 pc, respectively. Simulations with a Schmidt law of star formation yield a higher surface brightness ( ) in the Cartwheel's inner ring as compared to the observed values. The Toomre criterion for star formation fails to account for the observed sharp drop of massive star formation (MSF) in the inner ring. Numerical simulations indicate that a large shear near/at the position of the inner ring can raise the gas threshold for star formation and suppress MSF in the Cartwheel's inner regions. Hence, the Schmidt law has to be supplemented with a shear criterion for star formation in order to reproduce the observed radial distribution of in the Cartwheel's inner regions.
Key words: galaxies: individual: the Cartwheel -- galaxies: starburst
© ESO 2003