NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T02:27:19 PDT
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For refcode 2001A&A...372..406R:
Retrieve 70 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2001A&A...372..406R The impact of bars on the mid-infrared dust emission of spiral galaxies: global and circumnuclear properties. ROUSSEL H., SAUVAGE M., VIGROUX L., BOSMA A., BONOLI C., GALLAIS P., HAWARDEN T., MADDEN S., MAZZEI P. Received 14 December 2000/Accepted 22 March 2000 Abstract. We study the mid-infrared properties of a sample of 69 nearby spiral galaxies, selected to avoid Seyfert activity contributing a significant fraction of the central energetics, or strong tidal interaction, and to have normal infrared luminosities. These observations were obtained with ISOCAM, which provides an angular resolution of the order of 10" (half-power diameter of the point spread function) and low- resolution spectro-imaging information. Between 5 and 18 microns, we mainly observe two dust phases, aromatic infrared bands and very small grains, both out of thermal equilibrium. On this sample, we show that the global F_15_/F_7_ colors of galaxies are very uniform, the only increase being found in early-type strongly barred galaxies, consistent with previous IRAS studies. The F_15_/F_7_ excesses are unambiguously due to galactic central regions where bar-induced starbursts occur. However, the existence of strongly barred early-type galaxies with normal circumnuclear colors indicates that the relationship between a distortion of the gravitational potential and a central starburst is not straightforward. As the physical processes at work in central regions are in principle identical in barred and unbarred galaxies, and since this is where the mid-infrared activity is mainly located, we investigate the mid-infrared circumnuclear properties of all the galaxies in our sample. We show how surface brightnesses and colors are related to both the available molecular gas content and the mean age of stellar populations contributing to dust heating. Therefore, the star formation history in galactic central regions can be constrained by their position in a color-surface brightness mid-infrared diagram. Key words: galaxies: spiral - galaxies: ISM - stars: formation - infrared: ISM: continuum - ISM: lines and bands
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