Seismology of magnetic massive stars
About ten percent of stars with spectral type O, B or A have a detectable stable strong large-scale magnetic field at their surface, which most often resembles a magnetic dipole. These large-scale magnetic fields extend into the radiative layers of the OBA stars. Theory and simulations predict that...
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ftunivparis:oai:HAL:tel-02096862v1 2024-05-19T07:50:09+00:00 Seismology of magnetic massive stars Sismologie des étoiles chaudes magnétiques Buysschaert, Bram Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Université Paris sciences et lettres KU Leuven (1970-.) Coralie Laurence Neiner Conny Aerts 2018-04-26 https://theses.hal.science/tel-02096862 https://theses.hal.science/tel-02096862/document https://theses.hal.science/tel-02096862/file/buysschaert_archivage_78548.pdf en eng HAL CCSD NNT: 2018PSLEO004 tel-02096862 https://theses.hal.science/tel-02096862 https://theses.hal.science/tel-02096862/document https://theses.hal.science/tel-02096862/file/buysschaert_archivage_78548.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-02096862 Astrophysics [astro-ph]. Université Paris sciences et lettres; KU Leuven (1970-.), 2018. English. ⟨NNT : 2018PSLEO004⟩ Hot stars Pulsating stars Magnetic stars Asteroseismology Stellar magnetism Étoiles chaudes Étoiles pulsantes Étoiles magnetiques Astérosismologie Magnétisme stellaire [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] info:eu-repo/semantics/doctoralThesis Theses 2018 ftunivparis 2024-04-23T03:46:41Z About ten percent of stars with spectral type O, B or A have a detectable stable strong large-scale magnetic field at their surface, which most often resembles a magnetic dipole. These large-scale magnetic fields extend into the radiative layers of the OBA stars. Theory and simulations predict that they alter the internal structure and physical properties of these stars. In particular, it is expected that these large-scale magnetic fields enforce uniform rotation in the radiative layers and may suppress convective core overshooting. This has consequences for the evolution of these magnetic hot stars and it has implications for galactic evolution. Therefore, we observed and investigated the internal structure of magnetic hot stars. To do so, asteroseismology is the best method as the oscillation properties are directly related to the internal physical conditions. Various types of stellar oscillations are known and they are classified based on their dominant restoring force. Of these, gravity modes are governed by the buoyancy force and have their strongest probing power in the near core region, which is the domain of our interest.Our first objective was to identify pulsating magnetic hot stars and characterize their magnetic and seismic properties. We constructed a sample of magnetic candidate stars, by following indirect observational diagnostics for the presence of a large-scale magnetic field, to confirm with ground-based high-resolution optical spectropolarimetry taken with ESPaDOnS, Narval or HARPSpol. For two known magnetic stars, HD43317 and o Lup, we characterized the geometry and strength of the field in detail by analysing spectropolarimetric time series. For each star in our sample, we obtained high-cadence high-precision space-based photometry from BRITE, CoRoT, or K2 to study (periodic) variability. Only HD43317 revealed tens of stellar pulsations mode frequencies that pointed towards gravity modes. Only a few other stars studied showed a few pulsation mode frequencies, unsuitable for seismic ... Doctoral or Postdoctoral Thesis narval narval Université de Paris: Portail HAL |
institution |
Open Polar |
collection |
Université de Paris: Portail HAL |
op_collection_id |
ftunivparis |
language |
English |
topic |
Hot stars Pulsating stars Magnetic stars Asteroseismology Stellar magnetism Étoiles chaudes Étoiles pulsantes Étoiles magnetiques Astérosismologie Magnétisme stellaire [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] |
spellingShingle |
Hot stars Pulsating stars Magnetic stars Asteroseismology Stellar magnetism Étoiles chaudes Étoiles pulsantes Étoiles magnetiques Astérosismologie Magnétisme stellaire [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] Buysschaert, Bram Seismology of magnetic massive stars |
topic_facet |
Hot stars Pulsating stars Magnetic stars Asteroseismology Stellar magnetism Étoiles chaudes Étoiles pulsantes Étoiles magnetiques Astérosismologie Magnétisme stellaire [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] |
description |
About ten percent of stars with spectral type O, B or A have a detectable stable strong large-scale magnetic field at their surface, which most often resembles a magnetic dipole. These large-scale magnetic fields extend into the radiative layers of the OBA stars. Theory and simulations predict that they alter the internal structure and physical properties of these stars. In particular, it is expected that these large-scale magnetic fields enforce uniform rotation in the radiative layers and may suppress convective core overshooting. This has consequences for the evolution of these magnetic hot stars and it has implications for galactic evolution. Therefore, we observed and investigated the internal structure of magnetic hot stars. To do so, asteroseismology is the best method as the oscillation properties are directly related to the internal physical conditions. Various types of stellar oscillations are known and they are classified based on their dominant restoring force. Of these, gravity modes are governed by the buoyancy force and have their strongest probing power in the near core region, which is the domain of our interest.Our first objective was to identify pulsating magnetic hot stars and characterize their magnetic and seismic properties. We constructed a sample of magnetic candidate stars, by following indirect observational diagnostics for the presence of a large-scale magnetic field, to confirm with ground-based high-resolution optical spectropolarimetry taken with ESPaDOnS, Narval or HARPSpol. For two known magnetic stars, HD43317 and o Lup, we characterized the geometry and strength of the field in detail by analysing spectropolarimetric time series. For each star in our sample, we obtained high-cadence high-precision space-based photometry from BRITE, CoRoT, or K2 to study (periodic) variability. Only HD43317 revealed tens of stellar pulsations mode frequencies that pointed towards gravity modes. Only a few other stars studied showed a few pulsation mode frequencies, unsuitable for seismic ... |
author2 |
Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Université Paris sciences et lettres KU Leuven (1970-.) Coralie Laurence Neiner Conny Aerts |
format |
Doctoral or Postdoctoral Thesis |
author |
Buysschaert, Bram |
author_facet |
Buysschaert, Bram |
author_sort |
Buysschaert, Bram |
title |
Seismology of magnetic massive stars |
title_short |
Seismology of magnetic massive stars |
title_full |
Seismology of magnetic massive stars |
title_fullStr |
Seismology of magnetic massive stars |
title_full_unstemmed |
Seismology of magnetic massive stars |
title_sort |
seismology of magnetic massive stars |
publisher |
HAL CCSD |
publishDate |
2018 |
url |
https://theses.hal.science/tel-02096862 https://theses.hal.science/tel-02096862/document https://theses.hal.science/tel-02096862/file/buysschaert_archivage_78548.pdf |
genre |
narval narval |
genre_facet |
narval narval |
op_source |
https://theses.hal.science/tel-02096862 Astrophysics [astro-ph]. Université Paris sciences et lettres; KU Leuven (1970-.), 2018. English. ⟨NNT : 2018PSLEO004⟩ |
op_relation |
NNT: 2018PSLEO004 tel-02096862 https://theses.hal.science/tel-02096862 https://theses.hal.science/tel-02096862/document https://theses.hal.science/tel-02096862/file/buysschaert_archivage_78548.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1799468750084243456 |