A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum
Autor(a) principal: | |
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Data de Publicação: | 1992 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/88377 |
Resumo: | HR 3831 is a rapidly oscillating Ap star with a pulsational period of 11.67 min. The amplitude of this pulsation ranges from O to about 5 mmag as a function of the rotational aspect of the star. We use 268 hr of new high-speed photometric observa tions obtained in 1990 and 1991 plus 238 hr of published high-speed photometry from 1980, 1981, 1985 and 1986 to show that the period of pulsation amplitude modulation is equal to the period of mean-light variation. We use this to show that an interpretation of the pulsation-amplitude modulation as rotationally perturbed m modes requires that Cnt≤2 X 10-5 at the 3σ a confidence level, making that interpretation highly unlikely. We also show that the time of pulsation maximum pre cedes the time of mean-light extremum by 0.177 ± 0.007 d (0.062 ± 0.002 rotation periods), a 25σ a difference. The time of magnetic extremum coincides with the time of pulsation-amplitude maximum but differs from mean-light extremum by 0.158±0.032 d, a 5σ difference. This argues that HR3831 is an oblique pulsator with the magnetic axis and pulsation axis aligned, rather than a spotted pulsator with amplitude modulation caused by surface inhomogeneities. lt also indicates a deviation from cylindrical symmetry which makes the interpretation of the pulsation-amplitude modulation in terms of the oblique-pulsator model more complex than has yet been considered. By shifting the pulsation-amplitude variations into phase with the mean light variations and normalizing both data sets, we refine the rotation frequency for HR3831 to be vrot=0.3506333±0.0000006 d-1=4058.256±0.007 nHz, or Prot=2.851982±0.000005 d. |
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Kurtz, Donald W.Kanaan Neto, Antonio NemerMartinez, PeterTripe, P.2014-03-13T01:50:40Z19920035-8711http://hdl.handle.net/10183/88377000056054HR 3831 is a rapidly oscillating Ap star with a pulsational period of 11.67 min. The amplitude of this pulsation ranges from O to about 5 mmag as a function of the rotational aspect of the star. We use 268 hr of new high-speed photometric observa tions obtained in 1990 and 1991 plus 238 hr of published high-speed photometry from 1980, 1981, 1985 and 1986 to show that the period of pulsation amplitude modulation is equal to the period of mean-light variation. We use this to show that an interpretation of the pulsation-amplitude modulation as rotationally perturbed m modes requires that Cnt≤2 X 10-5 at the 3σ a confidence level, making that interpretation highly unlikely. We also show that the time of pulsation maximum pre cedes the time of mean-light extremum by 0.177 ± 0.007 d (0.062 ± 0.002 rotation periods), a 25σ a difference. The time of magnetic extremum coincides with the time of pulsation-amplitude maximum but differs from mean-light extremum by 0.158±0.032 d, a 5σ difference. This argues that HR3831 is an oblique pulsator with the magnetic axis and pulsation axis aligned, rather than a spotted pulsator with amplitude modulation caused by surface inhomogeneities. lt also indicates a deviation from cylindrical symmetry which makes the interpretation of the pulsation-amplitude modulation in terms of the oblique-pulsator model more complex than has yet been considered. By shifting the pulsation-amplitude variations into phase with the mean light variations and normalizing both data sets, we refine the rotation frequency for HR3831 to be vrot=0.3506333±0.0000006 d-1=4058.256±0.007 nHz, or Prot=2.851982±0.000005 d.application/pdfengMonthly Notices of the Royal Astronomical Society. London. Vol. 255, no. 2 (Mar. 1992), p. 289-294Astrofisica estelarAstronomia e astrofisicaA refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremumEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL000056054.pdf000056054.pdfTexto completo (inglês)application/pdf203202http://www.lume.ufrgs.br/bitstream/10183/88377/1/000056054.pdf05cd09634911c49509f86a09d3e343b6MD51TEXT000056054.pdf.txt000056054.pdf.txtExtracted Texttext/plain132http://www.lume.ufrgs.br/bitstream/10183/88377/2/000056054.pdf.txt39326fdf69b6cb79f80c640f8aeb8c75MD52THUMBNAIL000056054.pdf.jpg000056054.pdf.jpgGenerated Thumbnailimage/jpeg1956http://www.lume.ufrgs.br/bitstream/10183/88377/3/000056054.pdf.jpg13018cf306132dae9bbca636a07c5d5fMD5310183/883772022-02-22 05:06:19.550578oai:www.lume.ufrgs.br:10183/88377Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2022-02-22T08:06:19Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
title |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
spellingShingle |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum Kurtz, Donald W. Astrofisica estelar Astronomia e astrofisica |
title_short |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
title_full |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
title_fullStr |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
title_full_unstemmed |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
title_sort |
A refinement of the rotation period of the roap star hr 3831 and the discovery of a significant phase lag between the times of pulsation and magnetic extrema and the time of mean-light extremum |
author |
Kurtz, Donald W. |
author_facet |
Kurtz, Donald W. Kanaan Neto, Antonio Nemer Martinez, Peter Tripe, P. |
author_role |
author |
author2 |
Kanaan Neto, Antonio Nemer Martinez, Peter Tripe, P. |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Kurtz, Donald W. Kanaan Neto, Antonio Nemer Martinez, Peter Tripe, P. |
dc.subject.por.fl_str_mv |
Astrofisica estelar Astronomia e astrofisica |
topic |
Astrofisica estelar Astronomia e astrofisica |
description |
HR 3831 is a rapidly oscillating Ap star with a pulsational period of 11.67 min. The amplitude of this pulsation ranges from O to about 5 mmag as a function of the rotational aspect of the star. We use 268 hr of new high-speed photometric observa tions obtained in 1990 and 1991 plus 238 hr of published high-speed photometry from 1980, 1981, 1985 and 1986 to show that the period of pulsation amplitude modulation is equal to the period of mean-light variation. We use this to show that an interpretation of the pulsation-amplitude modulation as rotationally perturbed m modes requires that Cnt≤2 X 10-5 at the 3σ a confidence level, making that interpretation highly unlikely. We also show that the time of pulsation maximum pre cedes the time of mean-light extremum by 0.177 ± 0.007 d (0.062 ± 0.002 rotation periods), a 25σ a difference. The time of magnetic extremum coincides with the time of pulsation-amplitude maximum but differs from mean-light extremum by 0.158±0.032 d, a 5σ difference. This argues that HR3831 is an oblique pulsator with the magnetic axis and pulsation axis aligned, rather than a spotted pulsator with amplitude modulation caused by surface inhomogeneities. lt also indicates a deviation from cylindrical symmetry which makes the interpretation of the pulsation-amplitude modulation in terms of the oblique-pulsator model more complex than has yet been considered. By shifting the pulsation-amplitude variations into phase with the mean light variations and normalizing both data sets, we refine the rotation frequency for HR3831 to be vrot=0.3506333±0.0000006 d-1=4058.256±0.007 nHz, or Prot=2.851982±0.000005 d. |
publishDate |
1992 |
dc.date.issued.fl_str_mv |
1992 |
dc.date.accessioned.fl_str_mv |
2014-03-13T01:50:40Z |
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dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/88377 |
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0035-8711 |
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000056054 |
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http://hdl.handle.net/10183/88377 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Monthly Notices of the Royal Astronomical Society. London. Vol. 255, no. 2 (Mar. 1992), p. 289-294 |
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openAccess |
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