Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-11-19
Astronomy and Astrophysics
Astrophysics
Accepted for publication in MNRAS
Scientific paper
10.1111/j.1365-2966.2008.14278.x
(Abridged) The gravitational term for clouds and cores entering in the virial theorem is usually assumed to be equal to the gravitational energy, since the contribution to the gravitational force from the mass distribution outside the volume of integration is assumed to be negligible. Such approximation may not be valid in the presence of an important external net potential. In the present work we analyze the effect of an external gravitational field on the gravitational budget of a density structure. Our cases under analysis are (a) a giant molecular cloud (GMC) with different aspect ratios embedded within a galactic net potential, and (b) a molecular cloud core embedded within the gravitational potential of its parent molecular cloud. We find that for roundish GMCs, the tidal tearing due to the shear in the plane of the galaxy is compensated by the tidal compression in the z direction. The influence of the external effective potential on the total gravitational budget of these clouds is relatively small, although not necessarily negligible. However, for more filamentary GMCs, the external effective potential can be dominant and can even overwhelm self-gravity, regardless of whether its main effect on the cloud is to disrupt it or compress it. This may explain the presence of some GMCs with few or no signs of massive star formation, such as the Taurus or the Maddalena's clouds. In the case of dense cores embedded in their parent molecular cloud, we found that the gravitational content due to the external field may be more important than the gravitational energy of the cores themselves. This effect works in the same direction as the gravitational energy, i.e., favoring the collapse of cores. We speculate on the implications of these results for star formation models.
Ballesteros-Paredes Javier
Gomez Gilberto C.
Pichardo Barbara
Vázquez-Semadeni Enrique
No associations
LandOfFree
On the gravitational content of molecular clouds and their cores does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On the gravitational content of molecular clouds and their cores, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the gravitational content of molecular clouds and their cores will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-667523