Mon. Not. R. Astron. Soc., 473, 4754-4772 (2018/February-1)
Upper stellar mass limit by radiative feedback at low-metallicities: metallicity and accretion rate dependence.
FUKUSHIMA H., OMUKAI K. and HOSOKAWA T.
Abstract (from CDS):
We investigate the upper stellar mass limit set by radiative feedback for a forming star with various accretion rates and metallicities. Thus, we numerically solve the structures of both a protostar and its surrounding accretion envelope assuming a spherical symmetric and steady flow. The optical depth of the dust cocoon, a dusty part of the accretion envelope, differs for direct light from the stellar photosphere and diffuse light re-emitted as dust thermal emission. As a result, varying the metallicity qualitatively changes the way that the radiative feedback suppresses the accretion flow. With a fixed accretion rate of 10–3 M☉ yr–1, both direct and diffuse light jointly operate to prevent mass accretion at Z >= 10–1 Z☉. At Z <= 10–1 Z☉, the diffuse light is no longer effective and the direct light solely limits the mass accretion. At Z <= 10–3 Z☉, formation of the H II region plays an important role in terminating the accretion. The resultant upper mass limit increases with decreasing metallicity, from a few x 10 M☉ to ∼103 M☉ over Z = 1 Z☉-10–4 Z☉. We also illustrate how the radiation spectrum of massive star-forming cores changes with decreasing metallicity. First, the peak wavelength of the spectrum, which is located around 30 µm at 1 Z☉, shifts to < 3 µm at Z <= 0.1 Z☉. Secondly, a characteristic feature at 10 µm due to the amorphous silicate band appears as a dip at 1 Z☉, but changes to a bump at Z <= 0.1 Z☉. Using these spectral signatures, we can search massive accreting protostars in nearby low-metallicity environments with upcoming observations.
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
accretion, accretion discs - stars: formation - stars: massive - stars: Population II
View the reference in ADS
To bookmark this query, right click on this link: simbad:2018MNRAS.473.4754F and select 'bookmark this link' or equivalent in the popup menu