Torsional oscillations and observed rotational period
variations in early-type stars

J 2017

Torsional oscillations and observed rotational period variations in early-type stars

KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Gregory W. HENRY, Petr KURFÜRST, Marian KARLICKY et. al.

Basic information

Original name

Torsional oscillations and observed rotational period variations in early-type stars

Authors

KRTIČKA, Jiří (203 Czech Republic, guarantor, belonging to the institution), Zdeněk MIKULÁŠEK (203 Czech Republic, belonging to the institution), Gregory W. HENRY (840 United States of America), Petr KURFÜRST (203 Czech Republic, belonging to the institution) and Marian KARLICKY (203 Czech Republic)

Edition

Monthly Notices of the Royal Astronomical Society, Oxford, OXFORD UNIV PRESS, 2017, 0035-8711

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10308 Astronomy

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

URL

Impact factor

Impact factor: 5.194

RIV identification code

RIV/00216224:14310/17:00094567

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1093/mnras/stw2451

UT WoS

000393646300070

Keywords in English

MHD stars; chemically peculiar stars; early-type stars; magnetic field; stars rotation

Abstract

V originále

Some chemically peculiar stars in the upper main sequence show rotational period variations of unknown origin. We propose that these variations are a consequence of the propagation of internal waves in magnetic rotating stars that lead to the torsional oscillations of the star. We simulate the magnetohydrodynamic waves and calculate resonant frequencies for two stars that show rotational variations: CU Vir and HD 37776. We provide updated analyses of rotational period variations in these stars and compare our results with numerical models. For CU Vir, the length of the observed rotational period cycle, Pi=67.6(5) yr, can be well reproduced by the models, which predict a cycle length of 51 yr. However, for HD 37776, the observed lower limit of the cycle length, Pi>100 yr, is significantly longer than the numerical models predict. We conclude that torsional oscillations provide a reasonable explanation at least for the observed period variations in CU Vir.

Links

GA16-01116S, research and development project

Name: Atmosféry a okolohvězdné prostředí magnetických horkých hvězd

Investor: Czech Science Foundation

Citovat

KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Gregory W. HENRY, Petr KURFÜRST and Marian KARLICKY. Torsional oscillations and observed rotational period variations in early-type stars. Monthly Notices of the Royal Astronomical Society. Oxford: OXFORD UNIV PRESS, 2017, vol. 464, No 1, p. 933-939. ISSN 0035-8711. Available from: https://dx.doi.org/10.1093/mnras/stw2451.

@article{1359789,
   author = {Krtička, Jiří and Mikulášek, Zdeněk and Henry, Gregory W. and Kurfürst, Petr and Karlicky, Marian},
   article_location = {Oxford},
   article_number = {1},
   doi = {http://dx.doi.org/10.1093/mnras/stw2451},
   keywords = {MHD stars; chemically peculiar stars; early-type stars; magnetic field; stars rotation},
   language = {eng},
   issn = {0035-8711},
   journal = {Monthly Notices of the Royal Astronomical Society},
   title = {Torsional oscillations and observed rotational period variations in early-type stars},
   url = {http://adsabs.harvard.edu/abs/2017MNRAS.464..933K},
   volume = {464},
   year = {2017}
}

TY  - JOUR
ID  - 1359789
AU  - Krtička, Jiří - Mikulášek, Zdeněk - Henry, Gregory W. - Kurfürst, Petr - Karlicky, Marian
PY  - 2017
TI  - Torsional oscillations and observed rotational period variations in early-type stars
JF  - Monthly Notices of the Royal Astronomical Society
VL  - 464
IS  - 1
SP  - 933-939
EP  - 933-939
PB  - OXFORD UNIV PRESS
SN  - 00358711
KW  - MHD stars
KW  - chemically peculiar stars
KW  - early-type stars
KW  - magnetic field
KW  - stars rotation
UR  - http://adsabs.harvard.edu/abs/2017MNRAS.464..933K
L2  - http://adsabs.harvard.edu/abs/2017MNRAS.464..933K
N2  - Some chemically peculiar stars in the upper main sequence show rotational period variations of unknown origin. We propose that these variations are a consequence of the propagation of internal waves in magnetic rotating stars that lead to the torsional oscillations of the star. We simulate the magnetohydrodynamic waves and calculate resonant frequencies for two stars that show rotational variations: CU Vir and HD 37776. We provide updated analyses of rotational period variations in these stars and compare our results with numerical models. For CU Vir, the length of the observed rotational period cycle, Pi=67.6(5) yr, can be well reproduced by the models, which predict a cycle length of 51 yr. However, for HD 37776, the observed lower limit of the cycle length, Pi>100 yr, is significantly longer than the numerical models predict. We conclude that torsional oscillations provide a reasonable explanation at least for the observed period variations in CU Vir.
ER  -

KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Gregory W. HENRY, Petr KURFÜRST and Marian KARLICKY. Torsional oscillations and observed rotational period variations in early-type stars. \textit{Monthly Notices of the Royal Astronomical Society}. Oxford: OXFORD UNIV PRESS, 2017, vol.~464, No~1, p.~933-939. ISSN~0035-8711. Available from: https://dx.doi.org/10.1093/mnras/stw2451.

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