On the Radiation Problem of High Mass Stars.

Nyambuya, G. G. (2010) On the Radiation Problem of High Mass Stars.

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Official URL: http://ir.nust.ac.zw/xmlui/handle/123456789/298

Abstract

A massive star is defined to be one with a mass greater than 8 - 10M . Central to the on-going debate on how these objects [massive stars] come into being is the so-called Radiation Problem. For nearly forty years now, it has been argued that the radiation field emanating from massive stars is high enough to cause a global reversal of direct radial in-fall of material onto the nascent star. We argue that only in the case of a non-spinning isolated star does the gravitational field of the nascent star overcome the radiation field. An isolated non-spinning star is a non-spinning star without any circumstellar material around it, the gravitational field beyond its surface is described exactly by Newton?s inverse square law. The fact that massive stars should have their gravitational field being much stronger than their radiation field is drawn from the analysis of an isolated massive star, where in this case the gravitational field is much stronger than the radiation field. This conclusion is erroneously extended to the case of massive stars enshrouded in gas & dust. We find that, for the case of a non-spinning gravitating body where we take into consideration the circumstellar material, that at 8 - 10M , the radiation field will not reverse the radial in-fall of matter but a stalemate between the radiation and gravitational field will be achieved ? i.e., in-fall is halted but not reversed. This picture is very different from the common picture that is projected and accepted in the popular literature that at 8 - 10M , all the circumstellar material ? from the surface of the star, right up to the edge of the core; is expected to be swept away by the radiation field. We argue that massive stars should be able to come into being if the molecular core from which they form exhibit some rotation because a rotating core exhibits an ASGF which causes there to be an equatorial accretion disk and along this equatorial disk, the radiation field can not be much stronger than the gravitational field hence this equatorial accretion disk becomes the channel via which the nascent massive star accretes all of its material.,Supported by the Republic of South Africa?s National Research Foundation and the North West University, and Germany?s DAAD Programme via the University of K?oln.

Item Type: Article
Uncontrolled Keywords: stars, circumstellar matter,stars, formation ? radiative transfer
Divisions: Universities > State Universities > National University of Science and Technology
Depositing User: Mr. Edmore Sibanda
Date Deposited: 30 Nov 2015 23:01
Last Modified: 30 Nov 2015 23:01
URI: http://researchdatabase.ac.zw/id/eprint/1126

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