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L. Lanz (U. Maryland), S. E. Strom, S. C. Wolff (NOAO)
Two mechanisms have been proposed to account for the formation of massive stars: 1) an accretion process similar to the one that has been shown to apply to low mass stars; or 2) the merger of already formed protostars. If massive stars form by mergers, one might expect to find a systematic difference in the angular momentum of high and low mass stars; specifically, mergers are likely to lead to high values of angular momentum.
Spectroscopic observations of massive stars in NGC 6611 have been used to measure values of vsini. Stellar models have then been used to calculate the specific angular momentum (Jsini/M) for each star. When combined with vsini measurements for lower mass pre-main sequence stars on convective tracks in Orion, the data show that the upper limits on Jsini/M plotted as a function of M follow a simple power law throughout the mass range from 0.1-50 solar masses. The absence of any discontinuity in specific angular momentum suggests that there is a single mechanism for star formation throughout this entire mass range.
This research was supported in part by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program, which is funded by the National Science Foundation through Scientific Program Order No. 3 (AST-0243875) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.