Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503102
Title: Rapid rotation in Be stars : testing the null hypothesis - Be stars are all 'near-critical' rotators
Author: North, Matthew W. M.
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2008
Availability of Full Text:
Access from EThOS:
Full text unavailable from EThOS. Please try the link below.
Access from Institution:
Abstract:
The purpose of this thesis is to test the null hypothesis that all Be stars rotate close to their critical velocities. To do this, a grid of synthetic Be-star spectra is constructed, for Veq/Krit = 0.95, accounting for gravity darkening, limb darkening and viewing angle. This grid explores the full parameter space of the B star domain, subject to a minimum equatorial temperature constraint (TLOCai > 6000i*T), for a range of equatorial rotational velocities. The models are compared to 95 of the 116 Be stars in the Chauville et al. (2001) atlas. Of the stars modelled, 79 are fit acceptably, 12 show minor mismatches, the general cause of which is attributed to the presence of emission in the spectra. The four remaining fits are unacceptable, three due to a high degree of shell spectrum contamination, another as a result of a binary companion. In essence, the null hypothesis is believed to survive. One important implication of this is that velocities on the order of the sound speed are sufficient to promote the formation of Be-star circumstellar disks.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.503102  DOI: Not available
Share: