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D. Weistrop, D. Eggers, C.H. Nelson, M. Hancock, R. Bachilla (UNLV), M.E. Kaiser (JHU)
Using ultraviolet and visible wavelength imaging we have investigated the characteristics of starforming knots in the blue compact galaxy NGC 4194. Our sample is 99% complete for fluxes greater than 4.36x10-18 erg s-1 cm-2 Å-1 at \lambdae ~ 1595 Å(FUV) and 5.13x10-18 erg s-1 cm-2 Å-1 at \lambdae ~ 2010 Å(NUV). The complete sample contains 38 knots. Emission from these knots comprises 20% of the total detected FUV flux. Comparison with Starburst99 evolutionary tracks indicates knot reddening ranges from E(B-V) =0.00 to 0.70 mag. Reddening determined from emission lines in groundbased spectra is about twice that determined from the continuum, in agreement with previous results. Masses of the knots are also estimated from comparison with the Starburst99 evolutionary tracks.
The observed FUV luminosity function can be fit with a Gaussian with FWHM = 0.93 ± 0.27 in log flux centered at log flux = -16.10 ± 0.07. The bright end of the Gaussian can be fit by a power law with \alpha = -1.47 ± 0.27. Comparison of the estimated escape velocity with typical velocities in globular clusters suggests about half the knots are gravitationally bound. Estimate of the dynamical lifetime suggests almost all the knots are gravitationally bound. We conclude at least half the knots are candidate proto-globular clusters.
This work has been supported in part by NASA, under contract NAS5-31231, and through the Nevada Space Grant Consortium.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.