Doctor of Philosophy (PhD)
First Committee Member
Number of Pages
We have obtained STIS longslit spectra of the central region of the advanced merger NGC 4194. The spectra cover the wavelength ranges 1150--1750A in the UV and 2900--10270A in the visible. Results from the study of the properties of 14 star forming regions (knots) are presented. We determine the average E(B-V) = 1.1 mag using the combined Halpha+[N II] flux. If the [N II] contribution is 40% then the average E(B-V) = 0.7 mag. The metal abundances are found to be approximately solar. The average abundances calculated range from 8.1 +/- 0.5 to 8.9 +/- 0.1. The Halpha luminosities of the 14 observed knots yield a total SFR of ∼46 M⊙ yr-1. The sizes of the H II regions in the knots were determined from L(Hbeta) and range from ∼28 pc to ∼119 pc when a filling factor of 0.1 is assumed. The sizes are a factor of ∼2.15 smaller when a filling factor of 1 is assumed. Using Starburst99, and the EW(Halpha+[N II]) and EW(Hbeta), we estimate the ages of the star forming regions to be 5.5--10.5 Myr. From ground based spectra, the effective temperatures of the H II regions were found to be ∼11,000 K and the electron densities were determined to be ∼530 cm-3. We find that 8 of the knots likely formed with a Salpeter Initial Mass Function truncated at an upper mass of 30 M⊙ and that one of the knots likely formed with a standard Salpeter Initial Mass Function. We find that the knots formed with a median SFE ≈ 18%. The knots in our sample have stellar masses in the range ∼0.6 x 106 M⊙ up to ∼27 x 106 M⊙ . We suggest that the knots in our sample are likely the precursors of globular clusters.
Center; Forming; Interacting Galaxies; Ngc; Ngc 4194; Properties; Spectroscopic; Star; Star-forming; Starburst Galaxies; Study
University of Nevada, Las Vegas
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Hancock, Mark, "A spectroscopic study of the star -forming properties of the center of Ngc 4194" (2004). UNLV Retrospective Theses & Dissertations. 2608.