Volume 552, April 2013
|Number of page(s)||4|
|Published online||29 March 2013|
Physical properties of outflows⋆
Comparing CO- and H2O-based parameters in Class 0 sources
Department of Earth and Space SciencesChalmers University of Technology,
Onsala Space Observatory,
2 INAF – Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
3 Observatorio Astronómico Nacional (IGN), Calle Alfonso XII, 3., 28014 Madrid, Spain
4 Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
5 Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
Received: 30 January 2013
Accepted: 7 March 2013
Context. The observed physical properties of outflows from low-mass sources put constraints on possible ejection mechanisms. Historically, these quantities have been derived from CO using ground-based observations. It is, therefore, important to investigate whether parameters such as momentum rate (thrust) and mechanical luminosity (power) are the same when different molecular tracers are used.
Aims. Our objective is to determine the outflow momentum, dynamical time-scale, thrust, energy, and power using CO and H2O as tracers of outflow activity.
Methods. Within the framework of the Water In Star-forming regions with Herschel (WISH) key program, three molecular outflows from Class 0 sources have been mapped using the Heterodyne Instrument for the Far Infrared (HIFI) instrument aboard Herschel. We used these observations together with previously published H2 data to infer the physical properties of the outflows. We compared the physical properties derived here with previous estimates based on CO observations.
Results. Inspection of the spatial distribution of H2O and H2 confirms that these molecules are co-spatial. The most prominent emission peaks in H2 coincide with strong H2O emission peaks and the estimated widths of the flows when using the two tracers are comparable.
Conclusions. For the momentum rate and the mechanical luminosity, inferred values are not dependent on which tracer is used, i.e. the values agree to within a factor of 4 and 3, respectively.
Key words: ISM: molecules / ISM: jets and outflows / stars: formation / stars: winds, outflows
© ESO, 2013
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.