Hot stars in old stellar populations: a continuing need for intermediate ages |
| |
| Authors: | S C Trager Guy Worthey S M Faber Alan Dressler |
| |
| Institution: | School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS |
| |
| Abstract: | We present numerical investigations into the formation of massive stars from turbulent cores of density structure ρ∝ r ?1.5 . The results of five hydrodynamical simulations are described, following the collapse of the core, fragmentation and the formation of small clusters of protostars. We generate two different initial turbulent velocity fields corresponding to power-law spectra P ∝ k ?4 and P ∝ k ?3.5 , and we apply two different initial core radii. Calculations are included for both completely isothermal collapse, and a non-isothermal equation of state above a critical density (10?14 g cm?3) . Our calculations reveal the preference of fragmentation over monolithic star formation in turbulent cores. Fragmentation was prevalent in all the isothermal cases. Although disc fragmentation was largely suppressed in the non-isothermal runs due to the small dynamic range between the initial density and the critical density, our results show that some fragmentation still persisted. This is inconsistent with previous suggestions that turbulent cores result in the formation of a single massive star. We conclude that turbulence cannot be measured as an isotropic pressure term. |
| |
| Keywords: | hydrodynamics turbulence stars: formation |
|
|
