Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes

Details Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes

Aug 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006iaujd...8e..21i&link_type=abstract

Solar and Stellar Activity Cycles, 26th meeting of the IAU, Joint Discussion 8, 17-18 August 2006, Prague, Czech Republic, JD08,

Computer Science

Scientific paper

Rapidly rotating cool stars are known to have large magnetic regions at mid- to high-latitudes. Mid-latitude starspots and magnetic regions have characteristic lifetimes on the order of one month as observed using (Zeeman-) Doppler imaging techniques. The structure and detailed morphology of starspots are not observable at present. In this study, we present numerical simulations of the surface transport of bipolar magnetic regions (BMRs) and magnetic spots on stars which have radii and surface rotational shears of AB Doradus, the Sun, and the HR 1099 primary. The surface flux transport model is based on the magnetic induction equation for radial fields under the effects of surface differential rotation, meridional flow, and turbulent diffusion due to supergranulation. We calculate flux evolution and lifetimes of BMRs with different emergence latitudes, surface shear rates, and tilt angles. For BMRs comparable to the largest ones on the Sun, we find that varying the surface flows and tilt angle modifies the lifetimes over a range of a month. For very large BMRs (area fraction ~ 0.1) the assumption of Joy's law for the tilt angle - as compared to the case with zero tilt - leads to a significant increase of lifetime. Such regions can evolve to form circumpolar spots that live more than a year. Taking the observed weak latitudinal shear and the radius of the active subgiant component of HR 1099, we find longer BMR lifetimes as compared to the more strongly sheared AB Dor case. We have also considered the effect on decay and lifetimes of starspots if they are monolithic or a conglomerate of smaller spots of similar total size. We find these different configurations differ neither in their decay patterns, nor in their lifetimes. We also give an analytical explanation for the linear decay of magnetic flux in the monolithic-spot simulation.

Affiliated with

Also associated with

No associations

Rating

Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic Flux Transport on Active Cool Stars and Starspot Lifetimes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1784114