Issue |
A&A
Volume 569, September 2014
|
|
---|---|---|
Article Number | A7 | |
Number of page(s) | 11 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/201322176 | |
Published online | 10 September 2014 |
The Earliest Phases of Star formation (EPoS)
Temperature, density, and kinematic structure of the star-forming core CB 17⋆
1
Leiden Observatory, Leiden University,
PO Box 9513,
2300 RA
Leiden,
The Netherlands
e-mail:
schmalzl@strw.leidenuniv.nl
2
Max Planck Institute for Astronomy, Königstuhl 17, 69117
Heidelberg,
Germany
3
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,
Cambridge,
MA
02138,
USA
4
Universität zu Köln, Zülpicher Straße 77, 50937
Köln,
Germany
Received:
29
June
2013
Accepted:
25
May
2014
Context. The initial conditions for the gravitational collapse of molecular cloud cores and the subsequent birth of stars are still not well constrained. The characteristic cold temperatures (~10 K) in such regions require observations at sub-millimetre and longer wavelengths. The Herschel Space Observatory and complementary ground-based observations presented in this paper have the unprecedented potential to reveal the structure and kinematics of a prototypical core region at the onset of stellar birth.
Aims. This paper aims to determine the density, temperature, and velocity structure of the star-forming Bok globule CB 17. This isolated region is known to host (at least) two sources at different evolutionary stages: a dense core, SMM1, and a Class I protostar, IRS.
Methods. We modeled the cold dust emission maps from 100 μm to 1.2 mm with both a modified blackbody technique to determine the optical depth-weighted line-of-sight temperature and column density and a ray-tracing technique to determine the core temperature and volume density structure. Furthermore, we analysed the kinematics of CB17 using the high-density gas tracer N2H+.
Results. From the ray-tracing analysis, we find a temperature in the centre of SMM1 of T0 = 10.6 K, a flat density profile with radius 9.5 × 103 au, and a central volume density of nH,0 = 2.3 × 105 cm-3. The velocity structure of the N2H+ observations reveal global rotation with a velocity gradient of 4.3 km s-1 pc-1. Superposed on this rotation signature we find a more complex velocity field, which may be indicative of differential motions within the dense core.
Conclusions. SMM is a core in an early evolutionary stage at the verge of being bound, but the question of whether it is a starless or a protostellar core remains unanswered.
Key words: dust, extinction / ISM: molecules / ISM: kinematics and dynamics / stars: formation / stars: low-mass / ISM: individual objects: CB 17
The Herschel data (Fig. 2) including N- and T-maps in Fig. 3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A7
© ESO, 2014
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.