Publication Date:
2009-01-06
Description:
Self-gravity plays a decisive role in the final stages of star formation, where dense cores (size approximately 0.1 parsecs) inside molecular clouds collapse to form star-plus-disk systems. But self-gravity's role at earlier times (and on larger length scales, such as approximately 1 parsec) is unclear; some molecular cloud simulations that do not include self-gravity suggest that 'turbulent fragmentation' alone is sufficient to create a mass distribution of dense cores that resembles, and sets, the stellar initial mass function. Here we report a 'dendrogram' (hierarchical tree-diagram) analysis that reveals that self-gravity plays a significant role over the full range of possible scales traced by (13)CO observations in the L1448 molecular cloud, but not everywhere in the observed region. In particular, more than 90 per cent of the compact 'pre-stellar cores' traced by peaks of dust emission are projected on the sky within one of the dendrogram's self-gravitating 'leaves'. As these peaks mark the locations of already-forming stars, or of those probably about to form, a self-gravitating cocoon seems a critical condition for their existence. Turbulent fragmentation simulations without self-gravity-even of unmagnetized isothermal material-can yield mass and velocity power spectra very similar to what is observed in clouds like L1448. But a dendrogram of such a simulation shows that nearly all the gas in it (much more than in the observations) appears to be self-gravitating. A potentially significant role for gravity in 'non-self-gravitating' simulations suggests inconsistency in simulation assumptions and output, and that it is necessary to include self-gravity in any realistic simulation of the star-formation process on subparsec scales.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3817203/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3817203/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Goodman, Alyssa A -- Rosolowsky, Erik W -- Borkin, Michelle A -- Foster, Jonathan B -- Halle, Michael -- Kauffmann, Jens -- Pineda, Jaime E -- P41 RR013218/RR/NCRR NIH HHS/ -- P41 RR013218-12/RR/NCRR NIH HHS/ -- U54 EB005149/EB/NIBIB NIH HHS/ -- U54 EB005149-05/EB/NIBIB NIH HHS/ -- U54-EB005149/EB/NIBIB NIH HHS/ -- England -- Nature. 2009 Jan 1;457(7225):63-6. doi: 10.1038/nature07609.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Initiative in Innovative Computing at Harvard, Cambridge, Massachusetts 02138, USA. agoodman@cfa.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19122636" target="_blank"〉PubMed〈/a〉
Keywords:
Algorithms
;
Astronomy
;
Carbon Monoxide/analysis
;
Computer Simulation
;
*Gravitation
;
Stars, Celestial/*chemistry
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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