AAS 203rd Meeting, January 2004
Session 115 Dwarf, Irregular and Starburst Galaxies
Poster, Thursday, January 8, 2004, 9:20am-4:00pm, Grand Hall

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[115.16] The Mass Distribution and Star-Formation Rate of the Star-Forming Knots in NGC 4194

D. Weistrop, D. Eggers, M. Hancock, C.H. Nelson, R. Bachilla (UNLV), M.E. Kaiser (JHU)

We have identified a complete sample of 38 UV bright knots in the advanced merger NGC 4194, using Hubble Space Telescope images. These knots produce 20% of the ultraviolet emission from the area of the galaxy observed. The bright end of the knot flux distribution can be fit by a power law with exponent -1.47± 0.27 but the complete flux distribution is Gaussian. Comparison with reddened starburst evolutionary tracks indicates two-thirds of the knots are younger than 20 Myr. There is one concentration of very young knots less than 5 Myrs old. The knot masses are large, comparable to those found in other major merger galaxies. The mass distribution is a power law with exponent -1.85 ±0.24. The difference between the far ultraviolet flux distribution and the mass distribution can be understood by the rapid decrease in a knot's far ultraviolet flux due to stellar evolution. The star formation rate calculated from knots younger than 20 Myr is 6 solar masses per year, suggesting the star formation rate throughout the galaxy may be as high as 30 solar masses per year. The location and masses of individual star forming regions in NGC 4194 and the rate of star formation are typical of major merger galaxies.

Further investigation of NGC 4194 can be found in the poster 'A Spectroscopic Study of the Star-forming Properties of the Center of NGC 4194' by Hancock, et al. in this session.

This work is supported in part by NASA Guaranteed Time Observer funding to the STIS Science Team under NASA contract NAS5-31231 and through the Nevada Space Grant Consortium.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.