Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD51452

被引：57

作者：

Neiner, C. ^{[1
]}

Floquet, M. ^{[2
]}

Samadi, R. ^{[1
]}

Lara, F. Espinosa ^{[3
]}

Fremat, Y. ^{[4
]}

Mathis, S. ^{[1
,5
]}

Leroy, B. ^{[1
]}

de Batz, B. ^{[1
]}

Rainer, M. ^{[6
]}

Poretti, E. ^{[6
]}

Mathias, P. ^{[3
]}

Flo, J. Guarro

Buil, C. ^{[7
]}

Ribeiro, J.

Alecian, E. ^{[1
]}

Andrade, L. ^{[8
]}

Briquet, M. ^{[1
,9
]}

Diago, P. D. ^{[10
,12
]}

Emilio, M. ^{[11
]}

Fabregat, J. ^{[12
]}

Gutierrez-Soto, J. ^{[1
,10
,13
]}

Hubert, A. -M. ^{[2
]}

Janot-Pacheco, E. ^{[8
]}

Martayan, C. ^{[14
]}

Semaan, T. ^{[2
]}

Suso, J. ^{[12
]}

Zorec, J. ^{[15
]}

机构：

[1] Univ Paris Diderot, UPMC, Observ Paris, CNRS,UMR 8109,LESIA, F-92195 Meudon, France

[2] Univ Paris Diderot, Observ Paris, CNRS, UMR 8111,GEPI, F-92195 Meudon, France

[3] Univ Toulouse, CNRS, IRAP, UPS OMP, F-31400 Toulouse, France

[4] Royal Observ Belgium, B-1180 Brussels, Belgium

[5] CEA DSM CNRS Univ Paris Diderot, Ctr Saclay, IRFU SAp, Lab AIM Paris Saclay, F-91191 Gif Sur Yvette, France

[6] INAF Osservatorio Astron Brera, I-23807 Merate, LC, Italy

[7] Castanet Tolosan Observ, F-31320 Castanet Tolosan, France

[8] Univ Sao Paulo, BR-05508 Sao Paulo, Brazil

[9] Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium

[10] VIU, Castellon De La Plana 12006, Spain

[11] Univ Estadual Ponta Grossa, Observ Astron DEGEO, BR-4748 Ponta Grossa, Parana, Brazil

[12] Univ Valencia, Astron Observ, Valencia 46980, Spain

[13] Inst Astrofis Andalucia CSIC, Granada 18008, Spain

[14] ESO, Santiago 19001 19, Chile

[15] Univ Paris 06, CNRS, UMR 7095, Inst Astrophys Paris, F-75014 Paris, France

来源：

ASTRONOMY & ASTROPHYSICS | 2012年 / 546卷

关键词：

stars:; emission-line; Be; stars: individual: HD51452; stars: oscillations; stars: rotation; MAIN-SEQUENCE STARS; RAPIDLY ROTATING STARS; B-TYPE STARS; OPACITY MECHANISM; TIME-SERIES; OSCILLATIONS; ASTEROSEISMOLOGY; PULSATIONS; SIMULATIONS; CONVECTION;

D O I：

10.1051/0004-6361/201219820

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the kappa-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods. We analyzed the CoRoT and spectroscopic data with several methods: CLEAN-NG, FREQFIND, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d(-1). The main frequencies are also recovered in the spectroscopic data. In particular we find that HD51452 undergoes gravito-inertial modes that are not in the domain of those excited by the kappa-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts. Conclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD51452, which are stochastically excited gravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot Be stars.

引用

页数：14

共 12 条

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