TY - JOUR
T1 - ISO mid-infrared observations of normal star-forming galaxies
T2 - The key project sample
AU - Dale, Daniel A.
AU - Silbermann, Nancy A.
AU - Helou, George
AU - Valjavec, Emmanuel
AU - Malhotra, Sangeeta
AU - Beichman, Charles A.
AU - Brauher, James
AU - Contursi, Alessandra
AU - Dinerstein, Harriet L.
AU - Hollenbach, David J.
AU - Hunter, Deidre A.
AU - Kolhatkar, Sonali
AU - Lo, Kwok Yung
AU - Lord, Steven D.
AU - Lu, Nanyao Y.
AU - Rubin, Robert H.
AU - Stacey, Gordon J.
AU - Thronson, Harley A.
AU - Werner, Michael W.
AU - Corwin, Harold G.
PY - 2000/8
Y1 - 2000/8
N2 - We present mid-infrared maps and preliminary analysis for 61 galaxies observed with the ISOCAM instrument aboard the Infrared Space Observatory. Many of the general features of galaxies observed at optical wavelengths - spiral arms, disks, rings, and bright knots of emission - are also seen in the mid-infrared, except the prominent optical bulges are absent at 6.75 and 15 μm. In addition, the maps are quite similar at 6.75 and 15 μm, except for a few cases where a central starburst leads to lower Iv(6.75 μm)/Iv(15 μm) ratios in the inner region. We also present infrared flux densities and mid-infrared sizes for these galaxies. The mid-infrared color Iv(6.75 μm)/Iv(15 μm) shows a distinct trend with the far-infrared color Iv(60 μm)/Iv(100 μm). The quiescent galaxies in our sample [Iv(60 μm)/Iv(100 μm) ≲ 0.6] show Iv(6.75 μm)/Iv(15 μm) near unity, whereas this ratio drops significantly for galaxies with higher global heating intensity levels. Azimuthally averaged surface brightness profiles indicate the extent to which the mid-infrared flux is centrally concentrated, and provide information on the radial dependence of mid-infrared colors. The galaxies are mostly well resolved in these maps: almost half of them have <10% of their flux in the central resolution element. A comparison of optical and mid-infrared isophotal profiles indicates that the flux at 4400 Å near the optical outskirts of the galaxies is approximately 8 (7) times that at 6.75 μm (15 μm), comparable to observations of the diffuse quiescent regions of the Milky Way.
AB - We present mid-infrared maps and preliminary analysis for 61 galaxies observed with the ISOCAM instrument aboard the Infrared Space Observatory. Many of the general features of galaxies observed at optical wavelengths - spiral arms, disks, rings, and bright knots of emission - are also seen in the mid-infrared, except the prominent optical bulges are absent at 6.75 and 15 μm. In addition, the maps are quite similar at 6.75 and 15 μm, except for a few cases where a central starburst leads to lower Iv(6.75 μm)/Iv(15 μm) ratios in the inner region. We also present infrared flux densities and mid-infrared sizes for these galaxies. The mid-infrared color Iv(6.75 μm)/Iv(15 μm) shows a distinct trend with the far-infrared color Iv(60 μm)/Iv(100 μm). The quiescent galaxies in our sample [Iv(60 μm)/Iv(100 μm) ≲ 0.6] show Iv(6.75 μm)/Iv(15 μm) near unity, whereas this ratio drops significantly for galaxies with higher global heating intensity levels. Azimuthally averaged surface brightness profiles indicate the extent to which the mid-infrared flux is centrally concentrated, and provide information on the radial dependence of mid-infrared colors. The galaxies are mostly well resolved in these maps: almost half of them have <10% of their flux in the central resolution element. A comparison of optical and mid-infrared isophotal profiles indicates that the flux at 4400 Å near the optical outskirts of the galaxies is approximately 8 (7) times that at 6.75 μm (15 μm), comparable to observations of the diffuse quiescent regions of the Milky Way.
KW - Galaxies: ISM
KW - Galaxies: general
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U2 - 10.1086/301478
DO - 10.1086/301478
M3 - Article
AN - SCOPUS:0042732115
SN - 0004-6256
VL - 120
SP - 583
EP - 603
JO - Astronomical Journal
JF - Astronomical Journal
IS - 2
ER -