Dynamics and photodissociation region properties in IC 1396A

Y. Okada¹, R. Güsten², M. A. Requena-Torres², M. Röllig¹, P. Hartogh³, H.-W. Hübers^4,5, T. Klein², O. Ricken¹, R. Simon¹ and J. Stutzki¹

¹ I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
e-mail: okada@ph1.uni-koeln.de
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
³ Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Straße 2, 37191 Katlenburg-Lindau, Germany
⁴ Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
⁵ Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany

Received: 30 January 2012
Accepted: 2 March 2012

Abstract

Aims. We investigate the gas dynamics and the physical properties of photodissociation regions (PDRs) in IC 1396A, which is an illuminated bright-rimmed globule with internal structures created by young stellar objects.

Methods. Our mapping observations of the [C ii] emission in IC 1396A with GREAT onboard SOFIA revealed the detailed velocity structure of this region. We combined them with observations of the [C i] ³P₁−³P₀ and CO(4–3) emissions to study the dynamics of the different tracers and physical properties of the PDRs.

Results. The [C ii] emission generally matches the IRAC 8 μm, which traces the polycyclic aromatic hydrocarbon (PAH) emissions. The CO(4–3) emission peaks inside the globule, and the [C i] emission is strong in outer regions, following the 8  μm emission to some degree, but its peak is different from that of [C ii]. The [C ii] emitting gas shows a clear velocity gradient within the globule, which is not significant in the [C i] and CO(4–3) emission. Some clumps that are prominent in [C ii] emission appear to be blown away from the rim of the globule. The observed ratios of [C ii]/[C i] and [C ii]/CO(4–3) are compared to the KOSMA-τ PDR model, which indicates a density of 10⁴–10⁵ cm^-3.