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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358540.0, MPI für Astronomie / Publikationen_mpia
Dust and atomic gas in dwarf irregular galaxies of the M81 group: the SINGS and THINGS view
Authors:Walter, F.; Cannon, J. M.; Roussel, H.; Bendo, G. J.; Calzetti, D.; Dale, D. A.; Draine, B. T.; Helou, G.; Kennicutt, R. C.; Moustakas, J.; Rieke, G. H.; Armus, L.; Engelbracht, C. W.; Gordon, K.; Hollenbach, D. J.; Lee, J.; Li, A.; Meyer, M. J.; Murphy, E. J.; Regan, M. W.; Smith, J.-D.; Brinks, E.; de Blok, W. J. G.; Bigiel, F.; Thornley, M. D.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Start Page:102
End Page:114
Audience:Not Specified
Abstract / Description:We present observations of the dust and atomic gas phase in seven dwarf irregular galaxies of the M81 group from the Spitzer SINGS and VLA THINGS surveys. The Spitzer observations provide a first glimpse of the nature of the nonatomic ISM in these metal-poor (Z~0.1 Zsolar), quiescent (SFR~0.001-0.1 Msolar yr-1) dwarf galaxies. Most detected dust emission is restricted to H I column densities >1×1021 cm-2, and almost all regions of high H I column density (>2.5×1021 cm-2) have associated dust emission. Spitzer spectroscopy of two regions in the brightest galaxies (IC 2574 and Holmberg II) show distinctly different spectral shapes and aromatic features, although the galaxies have comparable gas-phase metallicities. This result emphasizes that the strength of the aromatic features is not a simple linear function of metallicity. We estimate dust masses of ~104-106 Msolar for the M81 dwarf galaxies, resulting in an average dust-to-gas ratio (Mdust/MHI) of ~3×10-4 (1.5×10-3 if only the H I that is associated with dust emission is considered); this is an order of magnitude lower than the typical value derived for the SINGS spirals. The dwarf galaxies are underluminous per unit star formation rate at 70 mum as compared to the more massive galaxies in SINGS by a factor of ~2. However, the average 70/160 mum ratio in the sample dwarf galaxies is higher than what is found in the other galaxies of the SINGS sample. This can be explained by a combination of a lower dust content in conjunction with a higher dust temperature in the dwarfs.
Free Keywords:Galaxies: Dwarf; galaxies: individual (DDO 53); galaxies: individual (DDO 165); galaxies: individual (Holmberg I); Galaxies: Individual: Name: Holmberg II; Galaxies: Individual: Alphanumeric: IC 2574; galaxies: individual (M81 dwA); galaxies: individual (M81 dwB); Galaxies: Irregular; Galaxies: ISM; Infrared: Galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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