Interstellar H_2 in M 33 detected with FUSE

Abstract

FUSE spectra of the four brightest H II regions in M 33 show absorption by interstellar gas in the Galaxy and in M 33. On three lines of sight molecular hydrogen in M 33 is detected. This is the first measurement of diffuse H_2 in absorption in a Local Group galaxy other than the Magellanic Clouds. A quantitative analysis is difficult because of the low signal to noise ratio and the systematic effects produced by having multiple objects in the FUSE aperture. We use the M 33 FUSE data to demonstrate in a more general manner the complexity of interpreting interstellar absorption line spectra towards multi-object background sources. We derive H_2 column densities of approximately 10^16 to 10^17 cm^{-2} along 3 sight lines (NGC 588, NGC 592, NGC 595). Because of the systematic effects, these values most likely represent upper limits and the non-detection of H_2 towards NGC 604 does not exclude the existence of significant amounts of molecular gas along this sight line.

10 pages, 5 figures, accepted for publication in A&A

References in corpus (6)

• Overview of the Far Ultraviolet Spectroscopic Explorer Mission
• On-Orbit Performance of the Far Ultraviolet Spectroscopic Explorer (FUSE) Satellite
• A FUSE Survey of Interstellar Molecular Hydrogen in the Small and Large Magellanic Clouds
• IMAPS Observations of Interstellar Neutral Argon and the Implications for Partially Ionized Gas
• Small-Scale Interstellar Na I Structure Toward M92
• The Star Formation Histories and Efficiencies of Two Giant HII Regions in M33

Cited by in corpus (10)

• A model for atomic and molecular interstellar gas: The Meudon PDR code
• A FUSE survey of high-latitude Galactic molecular hydrogen
• NGC 604, the Scaled OB Association (SOBA) Prototype. I: Spatial Distribution of the Different Gas Phases and Attenuation by Dust
• Probing The Multiphase Interstellar Medium Of The Dwarf Starburst Galaxy NGC 625 With FUSE Spectroscopy
• Directional Radiation and Photodissociation Regions in Molecular Hydrogen Clouds
• Far Ultraviolet Observations of Molecular Hydrogen in the Diffuse Interstellar Medium of Starburst Galaxies
• Interstellar abundances in the neutral and ionized gas of NGC604
• Far-Ultraviolet Spectroscopy of Star-Forming Regions in Nearby Galaxies: Stellar Populations and Abundance Indicators
• The giant HII region NGC 588 as a benchmark for 2D photoionisation models
• Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view