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Changes Of Dust Opacity With Density in the Orion A Molecular Cloud

dc.contributor.authorROY, Arnaud
dc.contributor.authorMARTIN, Peter G.
dc.contributor.authorPOLYCHRONI, Danae
hal.structure.identifierFORMATION STELLAIRE 2013
dc.contributor.authorBONTEMPS, Sylvain
hal.structure.identifierInstitut d'astrophysique spatiale [IAS]
dc.contributor.authorABERGEL, Alain
hal.structure.identifierRecherche en épidémiologie et biostatistique
dc.contributor.authorANDRE, Philippe
dc.contributor.authorARZOUMANIAN, Doris
dc.contributor.authorDI FRANCESCO, James
dc.contributor.authorHILL, Tracey
dc.contributor.authorKONYVES, Vera
dc.contributor.authorNGUYEN-LUONG, Quang
dc.contributor.authorPEZZUTO, Stefano
hal.structure.identifierFORMATION STELLAIRE 2013
dc.contributor.authorSCHNEIDER, N.
hal.structure.identifierINAF - Osservatorio Astrofisico di Arcetri [OAA]
dc.contributor.authorTESTI, Leonardo
hal.structure.identifierSLAC National Accelerator Laboratory [SLAC]
dc.contributor.authorWHITE, Glenn
dc.date.created2012-11-27
dc.date.issued2013
dc.identifier.issn0004-637X
dc.description.abstractEnWe have studied the opacity of dust grains at submillimeter wavelengths by estimating the optical depth from imaging at 160, 250, 350, and 500 um from the Herschel Gould Belt Survey and comparing this to a column density obtained from the 2MASS-derived color excess E(J-Ks). Our main goal was to investigate the spatial variations of the opacity due to "big" grains over a variety of environmental conditions and thereby quantify how emission properties of the dust change with column (and volume) density. The central and southern areas of the Orion A molecular cloud examined here, with NH ranging from 1.5X10^21 cm^-2 to 50X10^21 cm^-2, are well suited to this approach. We fit the multi-frequency Herschel spectral energy distributions (SEDs) of each pixel with a modified blackbody to obtain the temperature, T, and optical depth, \tau(1200), at a fiducial frequency of 1200 GHz (250 um). Using a calibration of NH/E(J-Ks)for the interstellar medium (ISM) we obtained the opacity (dust emission cross-section per H nucleon), \sigma_e(1200), for every pixel. From a value of ~ 1X10^-25 cm^2 H^-1 at the lowest column densities that is typical of the high latitude diffuse ISM, \sigma_e(1200) increases as NH^0.28 over the range studied. This is suggestive of grain evolution. Integrating the SEDs over frequency, we also calculated the specific power P (emission power per H) for the big grains. In low column density regions where dust clouds are optically thin to the interstellar radiation field (ISRF), P is typically 3.7 X 10^-31 W H^-1, again close to that in the high latitude diffuse ISM. However, we find evidence for a decrease of P in high column density regions, which would be a natural outcome of attenuation of the ISRF that heats the grains, and for localized increases for dust illuminated by nearby stars or embedded protostars.
dc.language.isoen
dc.publisherAmerican Astronomical Society
dc.title.enChanges Of Dust Opacity With Density in the Orion A Molecular Cloud
dc.typeArticle de revue
dc.identifier.doi10.1088/0004-637X/763/1/55
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
dc.identifier.arxiv1211.6475
bordeaux.journalThe Astrophysical Journal
bordeaux.pageid. 55
bordeaux.volume763
bordeaux.issue1
bordeaux.peerReviewedoui
hal.identifierhal-00838730
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00838730v1
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