Clumps and triggered star formation in ionized molecular clouds
Abstract
Infrared shells and bubbles are ubiquitous in the Galaxy and can generally be associated with H II regions formed around young, massive stars. In this paper, we use high-resolution 3D SPH simulations to explore the effect of a single O7 star emitting photons at 1049 s-1 and located at the centre of a molecular cloud with mass 104 M⊙ and radius 6.4 pc; the internal structure of the cloud is characterized by its fractal dimension, D (with 2.0≤ D ≤ 2.8), and the variance of its (lognormal) density distribution, σ O^2 (with 0.36 ≤ σ O^2 ≤ 1.42). Our study focuses on the morphology of the swept-up cold gas and the distribution and statistics of the resulting star formation. If the fractal dimension is low, the border of the H II region is dominated by extended shell-like structures, and these break up into a small number of massive high-density clumps which then spawn star clusters; star formation occurs relatively quickly, and delivers somewhat higher stellar masses. Conversely, if the fractal dimension is high, the border of the H II region is dominated by a large number of pillars and cometary globules, which contain compact dense clumps and tend to spawn single stars or individual multiple systems; star formation occurs later, the stellar masses are somewhat lower, and the stars are more widely distributed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2013
- DOI:
- 10.1093/mnras/stt1115
- arXiv:
- arXiv:1306.4317
- Bibcode:
- 2013MNRAS.435..917W
- Keywords:
-
- hydrodynamics;
- stars: formation;
- ISM: bubbles;
- H II regions;
- planetary nebulae: general;
- galaxies: ISM;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 12 pages, 11 figures, accepted for publication by MNRAS