TY - JOUR
T1 - Ultraviolet through far-infrared spatially resolved analysis of the recent star formation in M81 (NGC 3031)
AU - Pérez-González, Pablo G.
AU - Kennicutt, Robert C.
AU - Gordon, Karl D.
AU - Misselt, Karl A.
AU - Gil De Paz, Armando
AU - Engelbracht, Charles W.
AU - Rieke, George H.
AU - Bendo, George J.
AU - Bianchi, Luciana
AU - Boissier, Samuel
AU - Calzetti, Daniela
AU - Dale, Daniel A.
AU - Draine, Bruce T.
AU - Jarrett, Thomas H.
AU - Hollenbach, David
AU - Prescott, Moire K.M.
PY - 2006/9/10
Y1 - 2006/9/10
N2 - 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.
AB - 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.
KW - Dust, extinction
KW - Galaxies: ISM
KW - Galaxies: Individual (M81, NGC 3031)
KW - Galaxies: Photometry
KW - Galaxies: Spiral
KW - Galaxies: Stellar content
KW - Infrared: Galaxies
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UR - http://www.scopus.com/inward/citedby.url?scp=33750556196&partnerID=8YFLogxK
U2 - 10.1086/506196
DO - 10.1086/506196
M3 - Article
AN - SCOPUS:33750556196
SN - 0004-637X
VL - 648
SP - 987
EP - 1006
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 I
ER -