Volume 545, September 2012
|Number of page(s)||10|
|Section||Interstellar and circumstellar matter|
|Published online||27 August 2012|
13CO and C18O J = 2–1 mapping of the environment of the Class 0 protostellar core SMM 3 in Orion B9⋆
Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
Received: 27 April 2012
Accepted: 24 July 2012
Context. Observations of molecular spectral lines provide information on the gas kinematics and chemistry of star-forming regions.
Aims. We attempt to achieve a better understanding of the gas distribution and velocity field around the deeply embedded Class 0 protostar SMM 3 in the Orion B9 star-forming region.
Methods. Using the APEX 12-m telescope, we mapped the line emission from the J = 2–1 rotational transition of two CO isotopologues, 13CO and C18O, over a 4′ × 4′ region around Orion B9/SMM 3.
Results. Both the 13CO and C18O lines exhibit two well-separated velocity components at about 1.3 and 8.7 km s-1. The emission of both CO isotopologues is more widely distributed than the submillimetre dust continuum emission as probed by LABOCA. The LABOCA 870-μm peak position of SMM 3 is devoid of strong CO isotopologue emission, which is consistent with our earlier detection of strong CO depletion in the source. No signatures of a large-scale outflow were found towards SMM 3. The 13CO and C18O emission seen at ~1.3 km s-1 is concentrated into a single clump-like feature at the eastern part of the map. The peak H2 column density towards a C18O maximum of the low-velocity component is estimated to be ~1022 cm-2. A velocity gradient was found across both the 13CO and C18O maps. Interestingly, SMM 3 lies on the border of this velocity gradient.
Conclusions. The 13CO and C18O emission at ~1.3 km s-1 is likely to originate from the “low-velocity part” of Orion B. Our analysis suggests that it contains high density gas (~1022 H2 molecules per cm2), which conforms to our earlier detection of deuterated species at similarly low radial velocities. Higher-resolution observations would be needed to clarify the outflow activity of SMM 3. The sharp velocity gradient in the region might represent a shock front resulting from the feedback from the nearby expanding H ii region NGC 2024. The formation of SMM 3, and possibly of the other members of Orion B9, might have been triggered by this feedback.
Key words: stars: formation / stars: protostars / ISM: clouds / ISM: individual objects: Orion B9/SMM 3 / submillimeter: ISM / ISM: kinematics and dynamics
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.