The Mid-Infrared Extinction Law in the Ophiuchus, Perseus, and Serpens Molecular Clouds

Simple item page
dc.creatorChapman, Nicholas L.
dc.creatorMundy, Lee G.
dc.creatorLai, Shih-Ping
dc.creatorEvans II, Neal J.
dc.date2008-09-05
dc.date.accessioned2026-07-07T12:15:33Z
dc.date.available2026-07-07T12:15:33Z
dc.descriptionWe compute the mid-infrared extinction law from 3.6-24 microns in three molecular clouds: Ophiuchus, Perseus, and Serpens, by combining data from the "Cores to Disks" Spitzer Legacy Science program with deep JHKs imaging. Using a new technique, we are able to calculate the line-of-sight extinction law towards each background star in our fields. With these line-of-sight measurements, we create, for the first time, maps of the chi-squared deviation of the data from two extinction law models. Because our chi-squared maps have the same spatial resolution as our extinction maps, we can directly observe the changing extinction law as a function of the total column density. In the Spitzer IRAC bands, 3.6-8 microns, we see evidence for grain growth. Below $A_{K_s} = 0.5$, our extinction law is well-fit by the Weingartner & Draine (2001) $R_V = 3.1$ diffuse interstellar medium dust model. As the extinction increases, our law gradually flattens, and for $A_{K_s} >= 1$, the data are more consistent with the Weingartner & Draine $R_V = 5.5$ model that uses larger maximum dust grain sizes. At 24 microns, our extinction law is 2-4 times higher than the values predicted by theoretical dust models, but is more consistent with the observational results of Flaherty et al. (2007). Lastly, from our chi-squared maps we identify a region in Perseus where the IRAC extinction law is anomalously high considering its column density. A steeper near-infrared extinction law than the one we have assumed may partially explain the IRAC extinction law in this region.
dc.description38 pages, 19 figures in pre-print format. Accepted for publication in ApJ. A version with full-resolution figures can be found here: http://peggysue.as.utexas.edu/SIRTF/
dc.identifierhttps://arxiv.org/abs/0809.1106
dc.identifierhttp://arxiv.org/abs/0809.1106
dc.identifierAstrophys.J.690:496-511,2009
dc.identifierdoi:10.1088/0004-637X/690/1/496
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/211525
dc.subjectAstrophysics
dc.titleThe Mid-Infrared Extinction Law in the Ophiuchus, Perseus, and Serpens Molecular Clouds
dc.typetext

Files

Collections

arXiv