THE EFFECT OF MAGNETIC SPOTS ON STELLAR WINDS AND ANGULAR MOMENTUM LOSS

We simulate the effect of latitudinal variations in the location of star spots, as well as their magnetic field strength, on stellar angular momentum loss (AML) to the stellar wind. We use the Michigan solar corona global magnetohydrodynamic model, which incorporates realistic relation between the magnetic field topology and the wind distribution. We find that the spots' location significantly affects the stellar wind structure, and as a result, the total mass loss rate and AML rate. In particular, we find that the AML rate is controlled by the mass flux when spots are located at low latitudes but is controlled by an increased plasma density between the stellar surface and the Alfvén surface when spots are located at high latitudes. Our results suggest that there might be a feedback mechanism between the magnetic field distribution, wind distribution, AML through the wind, and the motions at the convection zone that generate the magnetic field. This feedback might explain the role of coronal magnetic fields in stellar dynamos.

[1]  Toulouse,et al.  The non-dipolar magnetic fields of accreting T Tauri stars , 2008, 0807.0758.

[2]  I. Sokolov,et al.  Three-dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations , 2008, 0805.3707.

[3]  G. Belle.  14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun , 2008 .

[4]  H. M. Antia,et al.  Solar Rotation Rate and Its Gradients During Cycle 23 , 2008, 0803.3619.

[5]  T. Gombosi,et al.  Validation of a synoptic solar wind model , 2008 .

[6]  R. Pudritz,et al.  Accretion-powered Stellar Winds. III. Spin-Equilibrium Solutions , 2008, 0801.0440.

[7]  R. Pudritz,et al.  Accretion-powered Stellar Winds. II. Numerical Solutions for Stellar Wind Torques , 2008, 0801.0436.

[8]  J. Lima,et al.  Magnetic braking in young late-type stars : The effect of polar spots , 2007, 0707.3588.

[9]  F. Favata,et al.  The coronal structure of AB Doradus determined from contemporaneous Doppler imaging and X-ray spectroscopy , 2007, astro-ph/0703619.

[10]  S. Cranmer,et al.  Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence , 2007, astro-ph/0703333.

[11]  M. Velli,et al.  A Semiempirical Magnetohydrodynamical Model of the Solar Wind , 2007 .

[12]  N. Sheeley,et al.  Sources of the Solar Wind at Ulysses during 1990-2006 , 2006 .

[13]  T. Suzuki.  Forecasting Solar Wind Speeds , 2006, astro-ph/0602062.

[14]  David R. Chesney,et al.  Space Weather Modeling Framework: A new tool for the space science community , 2005, Journal of Geophysical Research.

[15]  Astronomy,et al.  A further "degree of freedom" in the rotational evolution of stars , 2005, astro-ph/0508643.

[16]  J. Linsky,et al.  New Mass-Loss Measurements from Astrospheric Lyα Absorption , 2005, astro-ph/0506401.

[17]  A. V. Ballegooijen,et al.  Slingshot prominences above stellar X-ray coronae , 2005, astro-ph/0506229.

[18]  V. Holzwarth.  Impact of non-uniform surface magnetic fields on stellar winds , 2005, astro-ph/0506173.

[19]  K. Wood,et al.  The changing corona of LQ Hya , 2004 .

[20]  Sun Mi Chung,et al.  Doppler Shifts and Broadening and the Structure of the X-Ray Emission from Algol , 2004, astro-ph/0401583.

[21]  R. Taam,et al.  Magnetic Braking Revisited , 2003, astro-ph/0308361.

[22]  K. Wood,et al.  Polar fields for AB Doradus , 2003, astro-ph/0307210.

[23]  S. Owocki,et al.  Dynamical Simulations of Magnetically Channeled Line-driven Stellar Winds. I. Isothermal, Nonrotating, Radially Driven Flow , 2002, astro-ph/0201195.

[24]  C. Schrijver,et al.  On the Formation of Polar Spots in Sun-like Stars , 2001 .

[25]  R. Wichmann,et al.  Surface differential rotation and prominences of the Lupus post T Tauri star RX J1508.6–4423 , 2000 .

[26]  C. Arge,et al.  Improvement in the prediction of solar wind conditions using near‐real time solar magnetic field updates , 2000 .

[27]  M. Pinsonneault,et al.  The Angular Momentum Evolution of Very Low Mass Stars , 2000, astro-ph/0001065.

[28]  J. P. Goedbloed,et al.  Stellar Winds, Dead Zones, and Coronal Mass Ejections , 1999, astro-ph/9910152.

[29]  P. Roe,et al.  A Solution-Adaptive Upwind Scheme for Ideal Magnetohydrodynamics , 1999 .

[30]  J. Cassinelli,et al.  Introduction to Stellar Winds , 1999 .

[31]  J. Cassinelli,et al.  Introduction to Stellar Winds by Henny J. G. L. M. Lamers , 1999 .

[32]  A. Collier Cameron,et al.  Differential rotation and magnetic polarity patterns on AB Doradus , 1997 .

[33]  M. Pinsonneault,et al.  Theoretical Models of the Angular Momentum Evolution of Solar-Type Stars , 1997 .

[34]  S. Sofia,et al.  On the Origin of the Ultrafast Rotators in Young Star Clusters , 1996 .

[35]  S. Suess,et al.  Ulysses solar wind plasma observations from pole to pole , 1995 .

[36]  R. Jeffries.  Prominence activity on the rapidly rotating field star HD 197890 , 1993 .

[37]  A. Cameron,et al.  Prominence activity in G dwarfs of the α Persei cluster , 1992 .

[38]  N. Sheeley,et al.  Solar wind speed and coronal flux-tube expansion , 1990 .

[39]  S. Kawaler.  Angular momentum loss in low-mass stars , 1988 .

[40]  L. Mestel.  Magnetic Braking by a Stellar Wind—II , 1968 .

[41]  L. Davis,et al.  The angular momentum of the solar wind. , 1967 .

[42]  H. W. Babcock.  The Topology of the Sun's Magnetic Field and the 22-YEAR Cycle. , 1961 .

[43]  E. Parker.  Dynamics of the Interplanetary Gas and Magnetic Fields , 1958 .

[44]  Frank R Wilson.  N. R. A. , 1933 .

[45]  R. Rebolo,et al.  11th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun , 2001 .

[46]  J. Freeman,et al.  An empirical determination of the polytropic index for the free‐streaming solar wind using Helios 1 data , 1995 .

[47]  A. Cameron,et al.  Fast Hα variations on a rapidly rotating cool main sequence star – I. Circumstellar clouds , 1989 .

[48]  M. Altschuler,et al.  Magnetic fields and the structure of the solar corona , 1969 .