Far-Ultraviolet Spectroscopy of Star-Forming Regions in Nearby Galaxies: Stellar Populations and Abundance Indicators

Abstract

We present FUSE spectroscopy and supporting data for star-forming regions in nearby galaxies, to examine their massive-star content and explore the use of abundance and population indicators in this spectral range for high-redshift galaxies. New far-ultraviolet spectra are shown for four bright H II regions in M33 (NGC 588, 592, 595, and 604), the H II region NGC 5461 in M101, and the starburst nucleus of NGC 7714, supplemented by the very-low-metallicity galaxy I Zw 18. In each case, we see strong Milky Way absorption systems from H2, but intrinsic absorption within each galaxy is weak or undetectable, perhaps because of the "UV bias" in which reddened stars which lie behind molecular-rich areas are also heavily reddened. We see striking changes in the stellar-wind lines from these populations with metallicity, suggesting that C II, C III, C IV, N II, N III, and P V lines are potential tracers of stellar metallicity in star-forming galaxies. Three of these relations - involving N IV, C III, and P V - are nearly linear over the range from O/H=0.05--0.8 solar. The major difference in continuum shapes among these systems is that the giant H II complex NGC 604 has a stronger continuum shortward of 950 A than any other object in this sample. Small-number statistics would likely go in the other direction; we favor this as the result of a discrete star-forming event ~3 Myr ago, as suggested by previous studies of its stellar population. (Supported by NASA grant NAG5-8959)

Astronomical Journal, in press (July 2004). 8 figures; before publication, full-resolution figures are available as a single PDF file from http://www.astr.ua.edu/keel/fusefigs.pdf

References in corpus (8)

• Rest-Frame Ultraviolet Spectra of z~3 Lyman Break Galaxies
• Giant Molecular Clouds in M33 - I. BIMA All Disk Survey
• Abundances in the Neutral Interstellar Medium of I Zw 18 from FUSE Observations
• Molecular Hydrogen Optical Depth Templates for FUSE Data Analysis
• Synthetic High-Resolution Line Spectra of Star-Forming Galaxies Below 1200A
• Evidence for chemical evolution in the spectra of high redshift galaxies
• STIS Spectral Imagery of the OB Stars in NGC 604: The Most Luminous Stars
• Interstellar H_2 in M 33 detected with FUSE

Cited by in corpus (12)

• Spectral Modelling of Star-Forming Regions in the Ultraviolet: Stellar Metallicity Diagnostics for High Redshift Galaxies
• Chandra X-Ray Imaging of the Interacting Starburst Galaxy System NGC 7714/5: Tidal ULXs, Emergent Wind, and Resolved HII Regions
• Direct Constraints on the Extremely Metal-Poor Massive Stars Underlying Nebular C IV Emission from Ultra-Deep HST/COS Ultraviolet Spectroscopy
• The UK Infrared Telescope M33 monitoring project. IV. Variable red giant stars across the galactic disc
• The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
• Massive Stellar Content of Giant HII Regions in M 33 and M 101
• The Chandra ACIS Survey of M33 (ChASeM33): Investigating the Hot Ionized Medium in NGC604
• Diffuse Far-UV Line Emission from the Low-Redshift Lyman Break Galaxy Analog KISSR242
• Exploring the Correlation between $\mathrm{H}\alpha$-to-UV Ratio and Burstiness for Typical Star-forming Galaxies at $z\sim 2$
• Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view
• A Far-Ultraviolet View of Starburst Galaxies
• Investigating Galactic Fountains in M101: Insights from Ionized, UV emissions and Neutral Gas