English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Radiative transfer plays a major role in the process of star formation. Manysimulations of gravitational collapse of a cold gas cloud followed by theformation of a protostellar core use a grey treatment of radiative transfercoupled to the hydrodynamics. However, dust opacities which dominate extinctionshow large variations as a function of frequency. In this paper, we usedfrequency-dependent radiative transfer to investigate the influence of theopacity variations on the properties of Larson's first core. We used amultigroup M1 moment model in a 1D radiation hydrodynamics code to simulate thespherically symmetric collapse of a 1 solar mass cloud core. Monochromatic dustopacities for five different temperature ranges were used to compute Planck andRosseland means inside each frequency group. The results are very consistentwith previous studies and only small differences were observed between the greyand multigroup simulations. For a same central density, the multigroupsimulations tend to produce first cores with a slightly higher radius andcentral temperature. We also performed simulations of the collapse of a 10 and0.1 solar mass cloud, which showed the properties of the first core to beindependent of the initial cloud mass, with again no major differences betweengrey and multigroup models. For Larson's first collapse, where temperaturesremain below 2000 K, the vast majority of the radiation energy lies in the IRregime and the system is optically thick. In this regime, the greyapproximation does a good job reproducing the correct opacities, as long asthere are no large opacity variations on scales much smaller than the width ofthe Planck function. The multigroup method is however expected to yield moreimportant differences in the later stages of the collapse when high energy (UVand X-ray) radiation is present and matter and radiation are stronglydecoupled.

Simulations of protostellar collapse using multigroup radiation hydrodynamics. I. The first collapse