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J/A+A/533/A38       Extinction map of OMC-1                (Scandariato+, 2011)

The extinction map of the OMC-1 molecular cloud behind the Orion Nebula. Scandariato G., Robberto M., Pagano I., Hillenbrand L.A. <Astron. Astrophys. 533, A38 (2011)> =2011A&A...533A..38S
ADC_Keywords: Diffuse clouds ; H II regions ; Interstellar medium ; Nebulae ; Photometry, infrared ; Reddening Keywords: ISM: clouds - dust, extinction - open clusters and associations: individual: Orion Nebula Cluster - methods: statistical - techniques: photometric Abstract: The Orion Nebula and its associated young stellar cluster are located at the front-side of the optically thick OMC-1 molecular cloud. In order to disentangle the cluster members from background contamination, it is important to know the extinction provided by the OMC-1, which is poorly known, the available measurements yielding contradictory results. Our main goal is to derive a new extinction map of the OMC-1, obtaining information about the structure of the OMC-1 and the Orion Nebula Cluster. The most recent near-infrared catalog of stars is used to study the distribution of reddening across a 0.3deg2 area covering the Orion Nebula Cluster. On the basis of the observed (H,H-Ks) diagram, we establish a criterion for disentangling contaminants from bona-fide cluster members. For contaminant stars, interstellar reddenings are estimated by comparison with a synthetic galactic model. A statistical analysis is then performed to consistently account for local extinction, reddening and star-counts analysis. We derive the extinction map of the OMC-1 with angular resolution <5'. We also assemble a sample of candidate cluster members, for which we measure the extinction provided by the nebular environment. These extinction measurements are analyzed similarly to the contaminant sample, and an extinction map of the Orion Nebula is derived. The extinction provided by the OMC-1 is variable on spatial scales of a few arcminutes, while showing a general increase from the outskirts (AV∼6) to the direction of the Trapezium asterism (AV>30). The Orion Nebula extinction map is more irregular and optically thinner, with Av of the order of a few magnitudes. Both maps are consistent with the optical morphology, in particular the Dark Bay to the north-east of the Trapezium. Both maps also show the presence of a north-south high-density ridge, which confirms the filamentary structure of the Orion molecular complex inside which star formation is still taking place. Description: Extinction map of the OMC-1 and the Orion Nebula (with the corresponding error maps) in units of visyal extinction Av, extending over an area of ∼30'x40' roughly centered on θ1 OriC (IRCS position = 05:35:16.46-05:23:23.2). Objects: ---------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------- 05 35 14 -05 22.4 OMC-1 = NAME OMC-1 05 35 16.46 -05 23 23.2 θ1 OriC = * tet01 Ori ---------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file maps.dat 86 4 Summary of images of 6190x8237pixels (0.52x0.69deg) all centered at 05:34:58.51-05:28:07.4 (1pix=0.3") maps/* 0 4 FITS images
See also: J/A+A/466/949 : Velocities of OMC-1 flows (Nissen+, 2007) Byte-by-byte Description of file: maps.dat
Bytes Format Units Label Explanations
1- 15 A15 --- FileName Name of the map in subdirectory maps (1) 18- 86 A69 --- Title Title of the map
Note (1): all maps are 2D images of 6190x8237pixels of scale 0.3arcsec/pix, centered at (ICRS) 05:34:58.51-05:28:07.4 (field of view: 0.52x0.69deg)
Acknowledgements: Gaetano Scandariato, gscandariato(at)
(End) G. Scandariato [Univ. of Catania, Italy], P. Vannier [CDS] 19-Jul-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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