Gas absorption and dust extinction towards the Orion Nebula Cluster
- Author(s)
- Birgit Hasenberger, Jan Forbrich, Joao Alves, Scott J. Wolk, Stefan Meingast, Konstantin Getman, Ignazio Pillitteri
- Abstract
We characterise the relation between the gas and dust content of the interstellar medium towards young stellar objects in the Orion Nebula Cluster. X-ray observations provide estimates of the absorbing equivalent hydrogen column density N_H based on spectral fits. Near-infrared extinction values are calculated from intrinsic and observed colour magnitudes (J-H) and (H-K_s) as given by the VISTA Orion A survey. A linear fit of the correlation between column density and extinction values A_V yields an estimate of the N_H/A_V ratio. We investigate systematic uncertainties of the results by describing and (if possible) quantifying the influence of circumstellar material and the adopted extinction law, X-ray models, and elemental abundances on the N_H/A_V ratio. Assuming a Galactic extinction law with R_V=3.1 and solar abundances by Anders & Grevesse (1989), we deduce an N_H/A_V ratio of (1.39 +- 0.14) x 10^21 cm^-2 mag^-1 for Class III sources in the Orion Nebula Cluster where the given error does not include systematic uncertainties. This ratio is consistent with similar studies in other star-forming regions and approximately 31% lower than the Galactic value. We find no obvious trends in the spatial distribution of N_H/A_V ratios. Changes in the assumed extinction law and elemental abundances are demonstrated to have a relevant impact on deduced A_V and N_H values, respectively. Large systematic uncertainties associated with metal abundances in the Orion Nebula Cluster represent the primary limitation for the deduction of a definitive N_H/A_V ratio and the physical interpretation of these results.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Harvard-Smithsonian Center for Astrophysics, Pennsylvania State University, INAF Osservatorio Astronomico di Palermo
- Journal
- Astronomy & Astrophysics
- Volume
- 593
- No. of pages
- 10
- ISSN
- 0004-6361
- DOI
- https://doi.org/10.1051/0004-6361/201628517
- Publication date
- 09-2016
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/909996b3-c529-4258-94af-26634ad4f163