Date : 9/21 (Wed) [10:00 - 12:00] @ F620
Speaker: Dr. Kei Tanaka (University of Florida)
Title : Massive star formation by core accretion
Abstract: In this talk, I would like to introduce the theoretical view of massive star formation in various environment. Massive stars play important roles in many astrophysical fields: they are the main sources of mechanical, radiative and chemical feedback which regulate the evolution of interstellar medium and star formation activity in cosmic history. We are developing an analytical model of massive star formation by prestellar-cloud core collapse including the evolution of protostars and disks, and multiple feedback processes. Our model shows that the momentum by MHD disk wind drives strong outflow which sweeps up about 60% of the core material almost same as the case of low-mass star formation. In the formation of over-10Msun stars, the additional feedback by radiation, such as radiation pressure and photo-evaporation, stellar wind, reduces the core-to-star efficiency down to ~10% at minimum in our model. However, the dominant momentum output process is the MHD disk wind, and the radiation feedback do not limit the maximum mass which can formed by core accretion due to flashlight effect and dust absorption of EUV photons. Based on our accretion model, we also perform the radiative transfer calculation and make observational predictions to test theoretical model. We find that our model predictions are consistent with the properties of observed radio jets and winds. I'll also briefly explain similarities and differences of massive star formation processes at lower metallicities, e.g., metallicity dependence of radiation feedback and disk stability.


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