Structure Generation by Irradiation: What can GLIMPSE teach us about the ISM structure?

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dc.creatorHeitsch, F.
dc.creatorWhitney, B.
dc.creatorIndebetouw, R.
dc.creatorMeade, M. R.
dc.creatorBabler, B. L.
dc.creatorChurchwell, E.
dc.creator;
dc.date2006-07-14
dc.date.accessioned2026-07-07T10:39:35Z
dc.date.available2026-07-07T10:39:35Z
dc.descriptionDiffuse emission in the mid-infrared shows a wealth of structure, that lends itself to high-resolution structure analysis of the interstellar gas. A large part of the emission comes from polycyclic aromatic hydrocarbons, excited by nearby ultra-violet sources. Can the observed diffuse emission structure be interpreted as column density structure? We discuss this question with the help of a set of model molecular clouds bathed in the radiation field of a nearby O-star. The correlation strength between column density and ``observed'' flux density strongly depends on the absolute volume density range in the region. Shadowing and irradiation effects may completely alter the appearance of an object. Irradiation introduces additional small-scale structure and it can generate structures resembling shells around HII-regions in objects that do not possess any shell-like structures whatsoever. Nevertheless, structural information about the underlying interstellar medium can be retrieved. In the more diffuse regime ($n({HI})\lesssim 100$cm$^{-3}$), flux density maps may be used to trace the 3D density structure of the cloud via density gradients. Thus, while caution definitely is in order, mid-infrared surveys such as GLIMPSE will provide quantitative insight into the turbulent structure of the interstellar medium.
dc.description19 pages, 20 figures, submitted to ApJ
dc.identifierhttps://arxiv.org/abs/astro-ph/0607318
dc.identifierhttp://arxiv.org/abs/astro-ph/0607318
dc.identifierAstrophys.J.656:227-241,2007
dc.identifierdoi:10.1086/510522
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/181078
dc.subjectAstrophysics
dc.titleStructure Generation by Irradiation: What can GLIMPSE teach us about the ISM structure?
dc.typetext

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