Star formation through an accretion shock: a model for H+ blisters.
Abstract
A mechanism for the formation of stars is proposed in which subcondensations are compressed by passage through the accretion shock of a contracting parent cloud. It turns out that typical parent cloud masses are 10,000 to 50,000 solar masses, with radii 10-20 pc. When the pressure jump across the shock exceeds about 4, the largest subclouds are shattered by deceleration through the shock, whereas the smallest are not sufficiently compressed to be able to collapse. Only subclouds of intermediate mass (about 200 solar masses) are induced to form stars. Small groups of young stars are thereby generated on the periphery of the parent cloud. The observational appearance of such a system is calculated by solving the nonspherical Stromgren problem. It turns out that the resulting ionized regions ('blisters') are a natural consequence of this star formation mechanism. Characteristically, the maximum in the emission measure of a blister is displaced from the ionizing star in the direction of the center of the parent cloud. Also, double spectral line profiles with a velocity splitting up to 50 km/s are expected from the velocity structure in the blister.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1979
- Bibcode:
- 1979A&A....78..352I
- Keywords:
-
- Astronomical Models;
- Hydrogen Ions;
- Shock Wave Interaction;
- Star Formation;
- Stellar Mass Accretion;
- Deceleration;
- Early Stars;
- Fine Structure;
- Line Shape;
- Stellar Models;
- Astrophysics;
- Accretion:Star Formation;
- Shock Waves:Star Formation;
- Star Formation:Models