TY - JOUR
T1 - Gas absorption and dust extinction towards the Orion Nebula Cluster
AU - Hasenberger, Birgit
AU - Forbrich, Jan
AU - Alves, João
AU - Wolk, Scott J.
AU - Meingast, Stefan
AU - Getman, Konstantin V.
AU - Pillitteri, Ignazio
N1 - Publisher Copyright:
© ESO, 2016.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - Aims. We characterise the relation between the gas and dust content of the interstellar medium towards young stellar objects in the Orion Nebula Cluster. Methods. X-ray observations provide estimates of the absorbing equivalent hydrogen column density NH based on spectral fits. Near-infrared extinction values are calculated from intrinsic and observed colour magnitudes (J - H) and (H - Ks) as given by the VISTA Orion A survey. A linear fit of the correlation between column density and extinction values AV yields an estimate of the NH/AV 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 NH/AV ratio. Results. Assuming a Galactic extinction law with RV = 3.1 and solar abundances by Anders & Grevesse (1989, Geochim. Cosmochim. Acta, 53, 197), we deduce an NH/AV ratio of (1.39 ± 0.14) × 1021 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 NH/AV ratios. Changes in the assumed extinction law and elemental abundances are demonstrated to have a relevant impact on deduced AV and NH values, respectively. Large systematic uncertainties associated with metal abundances in the Orion Nebula Cluster represent the primary limitation for the deduction of a definitive NH/AV ratio and the physical interpretation of these results.
AB - Aims. We characterise the relation between the gas and dust content of the interstellar medium towards young stellar objects in the Orion Nebula Cluster. Methods. X-ray observations provide estimates of the absorbing equivalent hydrogen column density NH based on spectral fits. Near-infrared extinction values are calculated from intrinsic and observed colour magnitudes (J - H) and (H - Ks) as given by the VISTA Orion A survey. A linear fit of the correlation between column density and extinction values AV yields an estimate of the NH/AV 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 NH/AV ratio. Results. Assuming a Galactic extinction law with RV = 3.1 and solar abundances by Anders & Grevesse (1989, Geochim. Cosmochim. Acta, 53, 197), we deduce an NH/AV ratio of (1.39 ± 0.14) × 1021 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 NH/AV ratios. Changes in the assumed extinction law and elemental abundances are demonstrated to have a relevant impact on deduced AV and NH values, respectively. Large systematic uncertainties associated with metal abundances in the Orion Nebula Cluster represent the primary limitation for the deduction of a definitive NH/AV ratio and the physical interpretation of these results.
UR - http://www.scopus.com/inward/record.url?scp=84984924393&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84984924393&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201628517
DO - 10.1051/0004-6361/201628517
M3 - Article
AN - SCOPUS:84984924393
SN - 0004-6361
VL - 593
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A7
ER -