J/A+A/614/A65ivo://CDS.VizieR/J/A+A/614/A65doi:10.26093/cds/vizier.36140065CDSMeingast S.Alves J.Lombardi M.2019-03-25T13:53:49Z2019-01-16T06:46:25ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frinfrared-sourcesinfrared-photometrysurveysWe have investigated the shape of the extinction curve in the infrared up to ~25{mu}m for the Orion A star-forming complex. The basis of this work is near-infrared data acquired with the Visual and Infrared Survey Telescope for Astronomy, in combination with Pan-STARRS and mid-infrared Spitzer photometry. We obtain colour excess ratios for eight passbands by fitting a series of colour-colour diagrams. The fits are performed using Markov chain Monte Carlo methods, together with a linear model under a Bayesian formalism. The resulting colour excess ratios are directly interpreted as a measure of the extinction law. We show that the Orion A molecular cloud is characterized by flat mid-infrared extinction, similar to many other recently studied sightlines. Moreover, we find statistically significant evidence that the extinction law from ~1{mu}m to at least ~6{mu}m varies across the cloud. In particular, we find a gradient along galactic longitude, where regions near the Orion Nebula Cluster show a different extinction law compared to L1641 and L1647, the low-mass star-forming sites in the cloud complex. These variations are of the order of only 3% and are most likely caused by the influence of the massive stars on their surrounding medium. While the observed general trends in our measurements are in agreement with model predictions, both well-established and new dust grain models are not able to fully reproduce our infrared extinction curve. We also present a new extinction map featuring a resolution of 1' and revisit the correlation between extinction and dust optical depth. This analysis shows that cloud substructure, which is not sampled by background sources, affects the conversion factor between these two measures. In conclusion, we argue that specific characteristics of the infrared extinction law are still not well understood, but Orion A can serve as an unbiased template for future studies.2018A&A...614A..65Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/614/A65CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/587/A153 : VISION I. VISTA Orion A Survey (Meingast+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/614/A65https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/614/A65http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/614/A65https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/614/A65https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/614/A65http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/614/A65GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/614/A65/list (Information of fits file extensions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/614/A65/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/614/A65/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/614/A65/list?GETtext/xml+votable180.050000true84.4657503-6.66886540.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/614/A656/21436https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/614/A65?format=asciiInfrareddefaultJ/A+A/614/A65/listInformation of fits file extensionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintsizeSize of FITS file extensionKibytephys.size;meta.fitsintExt[1/4] Extension numbermeta.idintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS file extensionmeta.title;phys.angSize;meta.fitscharAssocDataAssociated Data web pagemeta.ref.urlchar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexed