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Session 68 - Disk Galaxies.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[68.08] HST WFPC-2 Observations of Typical Star Formation in M101

P. A. Scowen, J. J. Hester (Arizona State U.), J. S. Gallagher III, E. Wilcots (U. Wisconsin - Madison), W. Idt

We present narrow-band imaging of a field in the southern disk of M101. The field chosen for this study was intentionally picked to be removed from all regions of anomalous or enhanced star formation, such as regions close the the GEHR's NGC 5462 and NGC 5455, as well as being well separated from the tidally distorted arms to the west and north of the nucleus. The study focusses on an unbiassed sample of star formation regions limited only by the spatial resolution of the data (some 3.6 pc in the WFC chips).

We present evidence for sequential star formation, as well as triggered star formation across the field of study. The narrow-band images allow us to determine the nature of each cluster (young, old; HII region, SNR) and the ionized gas around it. We do see evidence for coherent but stochastic star formation around several very massive complexes leading us to conclude that while triggering may be initiated by the passage of a SDW subsequent star formation is a much more locally determined phenonena.

Using the [SII]/H\alpha ratio we can identify several SNR candidates which gives us important information about where local compression of the ISM is occuring, which might tell us something about subsequent star formation still to come. Many other objects of interest are pointed out, including several high-z hot bubbles that seem to be escaping upwards from the mid-plane where the OB stars are forming.

Future work with this field involves comparison with high resolution imaging of CO clouds, combined with neutral hydrogen maps of the same region.

Program listing for Wednesday