{"id":{"repo_id":"soton","oai_identifier":"oai:eprints.soton.ac.uk:167473"},"canonical_url":"https://search.dev.ndltd.org/etd/soton/oai:eprints.soton.ac.uk:167473","repository":{"repo_id":"soton","name":"University of Southampton","base_url":"https://eprints.soton.ac.uk/cgi/oai2"},"display":{"title":"Equilibria and oscillations of magnetised neutron stars","abstract":"We investigate equilibrium configurations and oscillation spectra of neutron stars,
modelled as rotating magnetised fluid bodies in Newtonian gravity. We also explore
the idea that these model neutron stars could have dynamics analogous to rigid-body
free precession.
In axisymmetry, the equations of magnetohydrodynamics reduce to a purely
toroidal-field case and a mixed-field case (with a purely poloidal-field limit). We
solve these equations using a nonlinear code which finds stationary rotating magnetised
stars by an iterative procedure. We find that despite the general nature of
our approach, the mixed-field configurations we produce are all dominated by their
poloidal component. We calculate distortions induced both by magnetic fields and
by rotation; our results suggest that the relationship between the magnetic energy
and the induced ellipticity should be close to linear for all known neutron stars.
We then investigate the oscillation spectra of neutron stars, using these stationary
configurations as a background on which to study perturbations. This is done
by evolving the perturbations numerically, making the Cowling approximation and
specialising to purely toroidal fields for simplicity. The results of the evolutions
show a number of magnetically-restored Alfv´en modes. We find that in a rotating
star pure inertial and pure Alfv´en modes are replaced by hybrid magneto-inertial
modes. We also show that magnetic fields appear to reduce the effect of the r-mode
instability.
Finally, we look at precession-like dynamics in magnetised fluid stars, using both
analytic and numerical methods. Whilst these studies are only preliminary, they
indicate deficiencies in previous research on this topic. We suggest ways in which
the problem of magnetised-fluid precession could be better understood.","abstract_html":"We investigate equilibrium configurations and oscillation spectra of neutron stars,<br/>modelled as rotating magnetised fluid bodies in Newtonian gravity. We also explore<br/>the idea that these model neutron stars could have dynamics analogous to rigid-body<br/>free precession.<br/><br/>In axisymmetry, the equations of magnetohydrodynamics reduce to a purely<br/>toroidal-field case and a mixed-field case (with a purely poloidal-field limit). We<br/>solve these equations using a nonlinear code which finds stationary rotating magnetised<br/>stars by an iterative procedure. We find that despite the general nature of<br/>our approach, the mixed-field configurations we produce are all dominated by their<br/>poloidal component. We calculate distortions induced both by magnetic fields and<br/>by rotation; our results suggest that the relationship between the magnetic energy<br/>and the induced ellipticity should be close to linear for all known neutron stars.<br/><br/>We then investigate the oscillation spectra of neutron stars, using these stationary<br/>configurations as a background on which to study perturbations. This is done<br/>by evolving the perturbations numerically, making the Cowling approximation and<br/>specialising to purely toroidal fields for simplicity. The results of the evolutions<br/>show a number of magnetically-restored Alfv´en modes. We find that in a rotating<br/>star pure inertial and pure Alfv´en modes are replaced by hybrid magneto-inertial<br/>modes. We also show that magnetic fields appear to reduce the effect of the r-mode<br/>instability.<br/><br/>Finally, we look at precession-like dynamics in magnetised fluid stars, using both<br/>analytic and numerical methods. Whilst these studies are only preliminary, they<br/>indicate deficiencies in previous research on this topic. We suggest ways in which<br/>the problem of magnetised-fluid precession could be better understood.","abstract_has_math":false,"creators":["Lander, Samuel Kenneth"],"institution":"University of Southampton","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Jones, D.I."],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-04","date_published":"2010-04","updated_at":"2026-07-24T04:36:17Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Jones, D.I."]},{"key":"dc:creator","label":"Author","values":["Lander, Samuel Kenneth"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-04"]},{"key":"dc:date.issued","label":"Date","values":["2010-04"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Mathematics (pre 2011 reorg)","School of Mathematics"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Southampton"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.soton.ac.uk/167473/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.soton.ac.uk/167473/1/Thesis.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["We investigate equilibrium configurations and oscillation spectra of neutron stars,
modelled as rotating magnetised fluid bodies in Newtonian gravity. We also explore
the idea that these model neutron stars could have dynamics analogous to rigid-body
free precession.
In axisymmetry, the equations of magnetohydrodynamics reduce to a purely
toroidal-field case and a mixed-field case (with a purely poloidal-field limit). We
solve these equations using a nonlinear code which finds stationary rotating magnetised
stars by an iterative procedure. We find that despite the general nature of
our approach, the mixed-field configurations we produce are all dominated by their
poloidal component. We calculate distortions induced both by magnetic fields and
by rotation; our results suggest that the relationship between the magnetic energy
and the induced ellipticity should be close to linear for all known neutron stars.
We then investigate the oscillation spectra of neutron stars, using these stationary
configurations as a background on which to study perturbations. This is done
by evolving the perturbations numerically, making the Cowling approximation and
specialising to purely toroidal fields for simplicity. The results of the evolutions
show a number of magnetically-restored Alfv´en modes. We find that in a rotating
star pure inertial and pure Alfv´en modes are replaced by hybrid magneto-inertial
modes. We also show that magnetic fields appear to reduce the effect of the r-mode
instability.
Finally, we look at precession-like dynamics in magnetised fluid stars, using both
analytic and numerical methods. Whilst these studies are only preliminary, they
indicate deficiencies in previous research on this topic. We suggest ways in which
the problem of magnetised-fluid precession could be better understood."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Equilibria and oscillations of magnetised neutron stars"]}]}],"canonical_facts":{"dc:contributor.advisor":["Jones, D.I."],"dc:creator":["Lander, Samuel Kenneth"],"dc:date":["2010-04"],"dc:date.issued":["2010-04"],"dc:description.abstract":["We investigate equilibrium configurations and oscillation spectra of neutron stars,
modelled as rotating magnetised fluid bodies in Newtonian gravity. We also explore
the idea that these model neutron stars could have dynamics analogous to rigid-body
free precession.
In axisymmetry, the equations of magnetohydrodynamics reduce to a purely
toroidal-field case and a mixed-field case (with a purely poloidal-field limit). We
solve these equations using a nonlinear code which finds stationary rotating magnetised
stars by an iterative procedure. We find that despite the general nature of
our approach, the mixed-field configurations we produce are all dominated by their
poloidal component. We calculate distortions induced both by magnetic fields and
by rotation; our results suggest that the relationship between the magnetic energy
and the induced ellipticity should be close to linear for all known neutron stars.
We then investigate the oscillation spectra of neutron stars, using these stationary
configurations as a background on which to study perturbations. This is done
by evolving the perturbations numerically, making the Cowling approximation and
specialising to purely toroidal fields for simplicity. The results of the evolutions
show a number of magnetically-restored Alfv´en modes. We find that in a rotating
star pure inertial and pure Alfv´en modes are replaced by hybrid magneto-inertial
modes. We also show that magnetic fields appear to reduce the effect of the r-mode
instability.
Finally, we look at precession-like dynamics in magnetised fluid stars, using both
analytic and numerical methods. Whilst these studies are only preliminary, they
indicate deficiencies in previous research on this topic. We suggest ways in which
the problem of magnetised-fluid precession could be better understood."],"dc:format":["text"],"dc:identifier.uri":["https://eprints.soton.ac.uk/167473/1/Thesis.pdf"],"dc:publisher.department":["Mathematics (pre 2011 reorg)","School of Mathematics"],"dc:publisher.institution":["University of Southampton"],"dc:relation.isreferencedby":["https://eprints.soton.ac.uk/167473/"],"dc:title":["Equilibria and oscillations of magnetised neutron stars"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T04:36:17Z"}