Origin of the Diffuse, Far Ultraviolet Emission in the Interarm Regions of M101

Abstract

We present images from the Solar Blind Channel on HST that resolve hundreds of far ultraviolet (FUV) emitting stars in two ~1 kpc${}^2$ interarm regions of the grand-design spiral M101. The luminosity functions of these stars are compared with predicted distributions from simple star formation histories, and are best reproduced when the star formation rate has declined recently (past 10-50 Myr). This pattern is consistent with stars forming within spiral arms and then streaming into the interarm regions. We measure the diffuse FUV surface brightness after subtracting all of the detected stars, clusters and background galaxies. A residual flux is found for both regions which can be explained by a mix of stars below our detection limit and scattered FUV light. The amount of scattered light required is much larger for the region immediately adjacent to a spiral arm, a bright source of FUV photons.

11 pages, 9 figures, accepted for publication in ApJ

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Cited by in corpus (6)

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• The Spatial Distribution of the Young Stellar Clusters in the Star Forming Galaxy NGC 628
• Galaxy Zoo: star-formation versus spiral arm number
• Star-Forming Environments Throughout the M101 Group
• The Panchromatic Hubble Andromeda Treasury XVII. Examining Obscured Star Formation with Synthetic Ultraviolet Flux Maps in M31
• Mid and Far-Infrared Color-Color Relations within Local Galaxies