HR: 1330h
AN: SP43B-01    [Abstracts]
TI: Turbulent Dynamos and the Minimum X-ray Flux in Solar-Type Main Sequence Stars
AU: * Bercik, D J
EM: bercik@ssl.berkeley.edu
AF: University of California,Berkeley, University of California at Berkeley Space Sciences Laboratory 7 Gauss Way, Berkeley, CA 94720-7450 United States
AU: Fisher, G H
EM: fisher@ssl.berkeley.edu
AF: University of California,Berkeley, University of California at Berkeley Space Sciences Laboratory 7 Gauss Way, Berkeley, CA 94720-7450 United States
AU: Johns-Krull, C M
EM: cmj@rice.edu
AF: Rice University, Department of Physics and Astronomy Rice University 6100 Main St. MS-108, Houston, TX 77005 United States
AU: Abbett, W P
EM: abbett@ssl.berkeley.edu
AF: University of California,Berkeley, University of California at Berkeley Space Sciences Laboratory 7 Gauss Way, Berkeley, CA 94720-7450 United States
AB: We investigate whether a small-scale turbulent dynamo can account quantitatively for the observed lower limit of X-ray surface flux in solar-type main sequence stars. Our approach is to use 3D numerical simulations of a turbulent dynamo driven by convection to characterize the dynamic behavior, magnetic field strengths, and filling factors in a non-rotating stratified medium, and to predict these magnetic properties at the surface of cool stars. We use simple applications of stellar structure theory for the convective envelopes of main-sequence stars to scale our simulations to the outer layers of stars in the F0--M0 spectral range, which allows us to estimate the unsigned magnetic flux on the surface of non-rotating reference stars. With these estimates we use the observed magnetic flux--X-ray flux correlation of Pevtsov et al. (2003) to predict the level of X-ray emission from such a turbulent dynamo, and find that our results compare well with observed lower limits of surface X-ray flux. This suggests that dynamo action from a convecting, non-rotating plasma is a viable alternative to acoustic heating models as an explanation for the basal emission level seen in chromospheric, transition region, and coronal diagnostics from late-type stars.
DE: 7524 Magnetic fields
DE: 7539 Stellar astronomy
DE: 7544 Stellar interiors and dynamo theory
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly