Evolution of the magnetic field of Betelgeuse from 2009-2017

被引:24
作者
Mathias, P. [1 ]
Auriere, M. [1 ]
Ariste, A. Lopez [2 ]
Petit, P. [2 ]
Tessore, B. [3 ]
Josselin, E. [1 ,3 ]
Lebre, A. [3 ]
Morin, J. [3 ]
Wade, G. [4 ]
Herpin, F. [5 ]
Chiavassa, A. [6 ]
Montarges, M. [7 ]
Konstantinova-Antova, R. [8 ,9 ]
Kervella, P. [10 ]
Perrin, G. [10 ]
Donati, J-F [2 ]
Grunhut, J. [11 ]
机构
[1] Univ Toulouse, IRAP, CNRS, UPS,CNES, 57 Ave Azereix, F-65000 Tarbes, France
[2] Univ Toulouse, CNES, UPS, IRAP,CNRS, 14 Ave Edouard Belin, F-31400 Toulouse, France
[3] Univ Montpellier, CNRS, LUPM, Pl Eugene Bataillon, F-34095 Montpellier, France
[4] Univ Toronto, Dunlap Inst Astron & Astrophys, Rm 101,50 St George St, Toronto, ON M5S 3H4, Canada
[5] Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N, Allee Geoffroy St Hilaire, F-33615 Pessac, France
[6] Univ Cote Azur, Observ Cote Azur, CNRS, CS 34229, F-06304 Nice 4, France
[7] Katholieke Univ Leuven, Inst Astron, Celestijnenlaan 200D B2401, B-3001 Leuven, Belgium
[8] Bulgarian Acad Sci, Inst Astron, 72 Tsarigradsko Shore, Sofia 1784, Bulgaria
[9] Bulgarian Acad Sci, NAO, 72 Tsarigradsko Shore, Sofia 1784, Bulgaria
[10] Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris,PSL Res Univ, 5 Pl Jules Janssen, F-92195 Meudon, France
[11] Royal Mil Coll Canada, Dept Phys, POB 17000, Kingston, ON ON K7K 4B4, Canada
基金
加拿大自然科学与工程研究理事会; 欧盟地平线“2020”;
关键词
stars: magnetic field; stars: individual: Betelgeuse; stars: late-type; supergiants; LONG SECONDARY PERIODS; STARS; CONVECTION; DIAGNOSIS; ESPADONS; I; AP;
D O I
10.1051/0004-6361/201732542
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Context. Betelgeuse is an M-type supergiant that presents a circularly polarized (Stokes V) signal in its line profiles, interpreted in terms of a surface magnetic field. Aims. The weak circular polarization signal has been monitored over 7.5 years in order to follow its evolution on different timescales, and eventually to determine its physical origin. Linear polarization measurements have also been obtained regularly in the last few years. Methods. We used both the ESPaDOnS and Narval spectropolarimeters to obtain high signal-to-noise ratio spectra, which were processed by means of the least-squares deconvolution method. In order to ensure the reality of the very weak circular polarization, special care has been taken to limit instrumental effects. In addition, several tests were performed on the Stokes V signal to establish its stellar and Zeeman origin. Results. We confirm the magnetic nature of the circular polarization, pointing to a surface magnetic field of the order of 1 G. The Stokes V profiles present variations over different timescales, the most prominent one being close to the long secondary period (LSP; around 2000 d for Betelgeuse) often invoked in red evolved stars. This long period is also dominant for all the other Stokes parameters. The circular polarization is tentatively modeled by means of magnetic field concentrations mimicking spots, showing in particular that the velocity associated with each "spot" also follows the long timescale, and that this signal is nearly always slightly redshifted. Conclusions. From the coupled variations of both linear and circular polarization signatures in amplitude, velocity and timescale, we favour giant convection cells as the main engine at the origin of polarization signatures and variations in all the Stokes parameters. This strengthens support for the hypothesis that large convective cells are at the origin of the LSP.
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页数:14
相关论文
共 60 条
[1]   Weak magnetic fields in Ap/Bp stars - Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy [J].
Auriere, M. ;
Wade, G. A. ;
Silvester, J. ;
Lignieres, F. ;
Bagnulo, S. ;
Bale, K. ;
Dintrans, B. ;
Donati, J. F. ;
Folsom, C. P. ;
Gruberbauer, M. ;
Hoa, A. Hui Bon ;
Jeffers, S. ;
Johnson, N. ;
Landstreet, J. D. ;
Lebre, A. ;
Lueftinger, T. ;
Marsden, S. ;
Mouillet, D. ;
Naseri, S. ;
Paletou, F. ;
Petit, P. ;
Power, J. ;
Rincon, F. ;
Strasser, S. ;
Toque, N. .
ASTRONOMY & ASTROPHYSICS, 2007, 475 (03) :1053-U111
[2]   The magnetic fields at the surface of active single G-K giants [J].
Auriere, M. ;
Konstantinova-Antova, R. ;
Charbonnel, C. ;
Wade, G. A. ;
Tsvetkova, S. ;
Petit, P. ;
Dintrans, B. ;
Drake, N. A. ;
Decressin, T. ;
Lagarde, N. ;
Donati, J. -F. ;
Roudier, T. ;
Lignieres, F. ;
Schroeder, K. -P. ;
Landstreet, J. D. ;
Lebre, A. ;
Weiss, W. W. ;
Zahn, J. -P. .
ASTRONOMY & ASTROPHYSICS, 2015, 574
[3]   Stellar polarimetry with narval [J].
Aurière, M .
MAGNETISM AND ACTIVITY OF THE SUN AND STARS: AN INTERNATIONAL CONFERENCE TO HONOR THE WORK OF JEAN-LOUIS LEROY, 2003, 9 :105-107
[4]   The magnetic field of Betelgeuse: a local dynamo from giant convection cells? [J].
Auriere, M. ;
Donati, J. -F. ;
Konstantinova-Antova, R. ;
Perrin, G. ;
Petit, P. ;
Roudier, T. .
ASTRONOMY & ASTROPHYSICS, 2010, 516
[5]   Discovery of a weak magnetic field in the photosphere of the single giant Pollux [J].
Auriere, M. ;
Wade, G. A. ;
Konstantinova-Antova, R. ;
Charbonnel, C. ;
Catala, C. ;
Weiss, W. W. ;
Roudier, T. ;
Petit, P. ;
Donati, J. -F. ;
Alecian, E. ;
Cabanac, R. ;
Van Eck, S. ;
Folsom, C. P. ;
Power, J. .
ASTRONOMY & ASTROPHYSICS, 2009, 504 (01) :231-237
[6]  
Auriere M., 2016, ASTRON ASTROPHYS, V591, pA119
[7]   THE MAGNETICALLY VARIABLE STAR HD-125248 [J].
BABCOCK, HW .
ASTROPHYSICAL JOURNAL, 1951, 114 (01) :1-+
[8]   Stellar Spectropolarimetry with Retarder Waveplate and Beam Splitter Devices [J].
Bagnulo, S. ;
Landolfi, M. ;
Landstreet, J. D. ;
Degl'Innocenti, E. Landi ;
Fossati, L. ;
Sterzik, M. .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 2009, 121 (883) :993-1015
[9]  
Barrick G, 2010, SPIE E, p4CB
[10]  
Bedecarrax I., 2013, Betelgeuse Workshop 2012. The Physics of Red Supergiants: Recent Advances and Open Questions, P161, DOI 10.1051/eas/1360018