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Long term observations of the high mass X-ray binary A0535+262/HDE 245770

Long term observations of the high mass X-ray binary A0535+262/HDE 245770
Long term observations of the high mass X-ray binary A0535+262/HDE 245770

This thesis contains the results of a long term monitoring campaign of the High Mass X-ray Binary A0535+262/ HDE 245770, a system consisting of an 09.5IIIe primary and a neutron star secondary in an eccentric (e=0.49) 111.3 day orbit. The system is of interest due to the large degree of variability seen at all energies and timescales. Since it is thought that the X-ray variability is due to changes in the circumstellar envelope of the primary, it is hoped that by understanding these changes an explanation for the X-ray variability will also be found.

Analysis of the optical and near IR spectral dataset reveals that the circumstellar envelope is commonly found to be in an asymmetric state, with a one armed density wave propagating through the inner regions of the disc. Modeling the most recent episode of this behaviour reveals that the density perturbation is constrained to lie close to the star (R~5R*). However, the periastron distance of the neutron star ((R~11R*) precludes any interaction. There is no evidence (He II emission, high velocity line components) for emission from a (transient) accretion disc in the spectroscopic data set, even though X-ray data reveals that presence of one at the time of the 1994 Giant X-ray outburst.

Photometric data reveals that the long term variability of the continuum emission can be well explained by free free and free bound emission from an isothermal circumstellar disc at Tdisc=0.8T* with a varying mass content; there is no evidence for emission from additional sources in the system (such as an accretion disc). Modeling this data shows that the Emission Measure of the disc varies between 9.2x1058cm-3 and 3.6 x 1060cm-3 between optically faint and bright states. If this is assumed to be due to a change in the base density of the disc it corresponds to a change by a factor of six.

University of Southampton
Clark, James Simon
Clark, James Simon

Clark, James Simon (1997) Long term observations of the high mass X-ray binary A0535+262/HDE 245770. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

This thesis contains the results of a long term monitoring campaign of the High Mass X-ray Binary A0535+262/ HDE 245770, a system consisting of an 09.5IIIe primary and a neutron star secondary in an eccentric (e=0.49) 111.3 day orbit. The system is of interest due to the large degree of variability seen at all energies and timescales. Since it is thought that the X-ray variability is due to changes in the circumstellar envelope of the primary, it is hoped that by understanding these changes an explanation for the X-ray variability will also be found.

Analysis of the optical and near IR spectral dataset reveals that the circumstellar envelope is commonly found to be in an asymmetric state, with a one armed density wave propagating through the inner regions of the disc. Modeling the most recent episode of this behaviour reveals that the density perturbation is constrained to lie close to the star (R~5R*). However, the periastron distance of the neutron star ((R~11R*) precludes any interaction. There is no evidence (He II emission, high velocity line components) for emission from a (transient) accretion disc in the spectroscopic data set, even though X-ray data reveals that presence of one at the time of the 1994 Giant X-ray outburst.

Photometric data reveals that the long term variability of the continuum emission can be well explained by free free and free bound emission from an isothermal circumstellar disc at Tdisc=0.8T* with a varying mass content; there is no evidence for emission from additional sources in the system (such as an accretion disc). Modeling this data shows that the Emission Measure of the disc varies between 9.2x1058cm-3 and 3.6 x 1060cm-3 between optically faint and bright states. If this is assumed to be due to a change in the base density of the disc it corresponds to a change by a factor of six.

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Published date: 1997

Identifiers

Local EPrints ID: 463007
URI: http://eprints.soton.ac.uk/id/eprint/463007
PURE UUID: 0726f742-4173-40d6-8af0-5872b9f60d40

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Date deposited: 04 Jul 2022 20:37
Last modified: 04 Jul 2022 20:37

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Author: James Simon Clark

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