AN AZIMUTHAL DYNAMO WAVE IN SPHERICAL SHELL CONVECTION

被引：26

作者：

Cole, Elizabeth ^{[1
]}

Kapyla, Petri J. ^{[1
,2
,3
]}

Mantere, Maarit J. ^{[1
,4
]}

Brandenburg, Axel ^{[2
,3
,5
]}

机构：

[1] Univ Helsinki, Dept Phys, FI-00014 Helsinki, Finland

[2] KTH Royal Inst Technol, NORDITA, SE-10691 Stockholm, Sweden

[3] Stockholm Univ, SE-10691 Stockholm, Sweden

[4] Aalto Univ, Dept Informat & Comp Sci, FI-00076 Aalto, Finland

[5] Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, SE-10691 Stockholm, Sweden

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2014年 / 780卷 / 02期

基金：

欧洲研究理事会; 瑞典研究理事会; 芬兰科学院;

关键词：

convection; dynamo; magnetohydrodynamics (MHD); stars: activity; stars: late-type; turbulence; FK COMAE BERENICES; DIFFERENTIAL ROTATION; II-PEGASI; MAGNETIC CYCLES; WEDGE GEOMETRY; FLIP-FLOPS; STARS; EVOLUTION; MODELS; STRATIFICATION;

D O I：

10.1088/2041-8205/780/2/L22

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report the discovery of an azimuthal dynamo wave of a low-order (m = 1) mode in direct numerical simulations (DNS) of turbulent convection in spherical shells. Such waves are predicted by mean-field dynamo theory and have been obtained previously in mean-field models. An azimuthal dynamo wave has been proposed as a possible explanation for the persistent drifts of spots observed on several rapidly rotating stars, as revealed through photometry and Doppler imaging. However, this has been judged unlikely because evidence for such waves from DNS has been lacking. Here we present DNS of large-scale magnetic fields showing a retrograde m = 1 mode. Its pattern speed is nearly independent of latitude and does not reflect the speed of the differential rotation at any depth. The extrema of magnetic m = 1 structures coincide reasonably well with the maxima of m = 2 structures of the temperature. These results provide direct support for the observed drifts being due to an azimuthal dynamo wave.

引用

页数：6

共 50 条

[1] SIMULATION STUDY OF A MAGNETOHYDRODYNAMIC DYNAMO - CONVECTION IN A ROTATING SPHERICAL-SHELL
KAGEYAMA, A
WATANABE, K
SATO, T
[J]. PHYSICS OF FLUIDS B-PLASMA PHYSICS, 1993, 5 (08): : 2793 - 2805
[2] Helicity inversion in spherical convection as a means for equatorward dynamo wave propagation
Duarte, Lucia D. V.
Wicht, Johannes
Browning, Matthew K.
Gastine, Thomas
[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2016, 456 (02) : 1708 - 1722
[3] Dynamo mechanism in a rotating spherical shell: competition between magnetic field and convection vortices
Ishihara, N
Kida, S
[J]. JOURNAL OF FLUID MECHANICS, 2002, 465 : 1 - 32
[4] Cellular dynamo in a rotating spherical shell
Getling, A
Simitev, RD
Busse, FH
[J]. ASTRONOMISCHE NACHRICHTEN, 2005, 326 (3-4) : 241 - 244
[5] A dynamo wave in a thin shell
Kuzanyan, KM
Sokolov, DD
[J]. ASTRONOMICHESKII ZHURNAL, 1996, 73 (03): : 469 - 476
[6] Dynamo effect with inertial modes in a spherical shell ?
Rieutord, M
Valdettaro, L
[J]. DYNAMO AND DYNAMICS, A MATHEMATICAL CHALLENGE, 2001, 26 : 271 - 277
[7] Azimuthal winds, convection and dynamo action in the polar regions of planetary cores
Sreenivasan, Binod
Jones, Chris A.
[J]. GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS, 2006, 100 (4-5): : 319 - 339
[8] Numerical modeling of magnetohydrodynamic convection in a rapidly rotating spherical shell: Weak and strong field dynamo action
Kuang, WJ
Bloxham, J
[J]. JOURNAL OF COMPUTATIONAL PHYSICS, 1999, 153 (01) : 51 - 81
[9] CONVECTION IN A SPHERICAL-SHELL
ZEBIB, A
SCHUBERT, G
STRAUS, JM
[J]. BULLETIN OF THE AMERICAN PHYSICAL SOCIETY, 1978, 23 (08): : 1008 - 1008
[10] Fingering convection in a spherical shell
Tassin, Theo
Gastine, Thomas
Fournier, Alexandre
[J]. JOURNAL OF FLUID MECHANICS, 2024, 988

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