SIMBAD references

2018MNRAS.473.4754F - 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.


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.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): accretion, accretion discs - stars: formation - stars: massive - stars: Population II

Simbad objects: 2

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