Ultraviolet through far-infrared spatially resolved analysis of the recent star formation in M81 (NGC 3031)

Pablo G. Pérez-González, Robert C. Kennicutt, Karl D. Gordon, Karl A. Misselt, Armando Gil De Paz, Charles W. Engelbracht, George H. Rieke, George J. Bendo, Luciana Bianchi, Samuel Boissier, Daniela Calzetti, Daniel A. Dale, Bruce T. Draine, Thomas H. Jarrett, David Hollenbach, Moire K.M. Prescott

Research output: Contribution to journalArticlepeer-review

111 Scopus citations


The recent star formation (SF) in the early-type spiral galaxy M81 is characterized using imaging observations from the far-ultraviolet to the far-infrared. We compare these data with models of the stellar, gas, and dust emission for subgalactic regions. Our results suggest the existence of a diffuse dust emission not directly linked to the recent star formation. We find a radial decrease of the dust temperature and dust mass density, and in the attenuation of the stellar light. The IR emission in M81 can be modeled with three components: (1) cold dust with a temperature 〈Tc〉 = 18 ± 2 K, concentrated near the H II regions but also presenting a diffuse distribution; (2) warm dust with 〈Tw〉 = 53 ± 7 K, directly linked with the H II regions; and (3) aromatic molecules, with diffuse morphology peaking around the H II regions. We derive several relationships to obtain total IR luminosities from IR monochromatic fluxes, and we compare five different star formation rate (SFR) estimators for H II regions in M81 and M51: the UV, Hα, and three estimators based on Spitzer data. We find that the Hα luminosity absorbed by dust correlates tightly with the 24 μm emission. The correlation with the total IR luminosity is not as good. Important variations from galaxy to galaxy are found when estimating the total SFR with the 24 μm or the total IR emission alone. The most reliable estimations of the total SFRs are obtained by combining the Hα emission (or the UV) and an IR luminosity (especially the 24 μm emission), which probe the unobscured and obscured SF, respectively. For the entire M81 galaxy, about 50% of the total SF is obscured by dust. The percentage of obscured SF ranges from 60% in the inner regions of the galaxy to 30% in the outer zones.

Original languageEnglish (US)
Pages (from-to)987-1006
Number of pages20
JournalAstrophysical Journal
Issue number2 I
StatePublished - Sep 10 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Dust, extinction
  • Galaxies: ISM
  • Galaxies: Individual (M81, NGC 3031)
  • Galaxies: Photometry
  • Galaxies: Spiral
  • Galaxies: Stellar content
  • Infrared: Galaxies


Dive into the research topics of 'Ultraviolet through far-infrared spatially resolved analysis of the recent star formation in M81 (NGC 3031)'. Together they form a unique fingerprint.

Cite this