Spatial variation of the cooling lines in the Orion Bar from Hersehel/PACS

dc.contributor.authorBernard-Salas, J.
dc.contributor.authorHabart, E.
dc.contributor.authorArab, H.
dc.contributor.authorAbergel, A.
dc.contributor.authorDartois, E.
dc.contributor.authorMartin, P.
dc.contributor.authorBontemps, S.
dc.contributor.authorJoblin, C.
dc.contributor.authorWhite, G. J.
dc.contributor.authorBernard, J.-P.
dc.contributor.authorNaylor, David A.
dc.descriptionSherpa Romeo green journal. Reproduced with permission from Astronomy & Astrophysics, ©ESO.en_US
dc.description.abstractContext. The energetics in photo-dissociation regions (PDRs) are mainly regulated by the balance between the heating from the photo-electric effect acting on dust grains, and the cooling via the copious emission of photons in far-infrared lines. The Orion Bar is a luminous and nearby PDR, which presents to the observer an ideal edge-on orientation in which to study this energy balance. Spatially resolved studies of such a nearby system are essential as they enable us to characterise the physical processes that control the energetics of the regions and can serve as templates for distant systems where these processes cannot be disentangled. Aims. We characterise the emission of the far-infrared fine-structure lines of [Cii](158 μm),[Oi](63and145 μm),and[Nii](122 μm) that trace the gas local conditions, via spatially resolved observations of the Orion Bar. The observed distribution and variation of the lines are discussed in relation to the underlying geometry and linked to the energetics associated with the Trapezium stars. Methods. Herschel/PACS observations are used to map the spatial distribution of these fine-structure lines across the Bar, with a spatial resolution between 4 and 11 and covering a total square area of about 120 ×105 . The spatial profile of the emission lines are modelled using the radiative transfer code Cloudy. Results. TheHerschel observations reveal in unprecedented detail the morphology of the Bar.The spatial distribution of the [Cii] line coincides with that of the [Oi] lines. The [Nii] line peaks closer to the ionising star than the other three lines, but with a small region of overlap. We can distinguish several knots of enhanced emission within the Bar indicating the presence of an in homogenous and structured medium. The emission profiles cannot be reproduced by a single PDR, clearly indicating that, besides the Bar, there is a significant contribution from additional PDR(s)over the area studied. The combination of both the [Nii] and [Oi] 145 μm lines can be used to estimate the [Cii] emission and distinguish between it sionised or neutral origin. We have calculated how much[Cii] emission comes from the neutral and ionised region, and find that at least ∼82% originates from the photo-dissocciation region. Together, the [Cii] 158 μm and [Oi] 63 and 145 μm lines account for∼90% of the power emitted by the main cooling lines in the Bar (including CO, H2, etc.), with [Oi] 63μm alone accounting for 72% of the total.en_US
dc.identifier.citationBernard-Salas, J., Habart, E., Arab,H., Abergel, A., Dartois, E., Martin, P.,...Naylor, D. (2012). Spatial variation of the cooling lines in the Orion Bar from Herschel/PACS. Astronomy & Astrophysics, 538,A37. doi: 10.1051/0004-6361/201118083en_US
dc.publisherEDP Sciencesen_US
dc.publisher.departmentDepartment of Physics & Astronomyen_US
dc.publisher.facultyArts and Scienceen_US
dc.publisher.institutionInstitut d'Astrophysique Spatialeen_US
dc.publisher.institutionCanadian Institute for Theoretical Astrophysicsen_US
dc.publisher.institutionLaboratoire d'Astrophysique de Bordeauxen_US
dc.publisher.institutionUniversité de Toulouseen_US
dc.publisher.institutionOpen Universityen_US
dc.publisher.institutionRutherford Appleton Laboratoryen_US
dc.publisher.institutionUniversity of Lethbridgeen_US
dc.subjectISM: lines and bandsen_US
dc.subjectH II regionsen_US
dc.subjectInfrared: generalen_US
dc.subjectISM: individual objectsen_US
dc.subjectOrion Baren_US
dc.subject.lcshInterstellar matter
dc.subject.lcshHerschel Space Observatory (Spacecraft)
dc.titleSpatial variation of the cooling lines in the Orion Bar from Hersehel/PACSen_US
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
1.5 MB
Adobe Portable Document Format
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
1.75 KB
Item-specific license agreed upon to submission