Modeling Atmospheric Activity of Cool Stars
Carolus J. Schrijver
Institute: Lockheed Martin Advanced Technology Center
Contact Email: schryver@lmsal.com
Abstract:
This review discusses a set of simple models for cool-star activity with
which we
compute (1) photospheric field patterns on stars of different activity levels,
(2) the associated outer-atmospheric field
configurations, and (3) the soft X-ray emission that is expected to
result from the ensemble
of loop atmospheres in the coronae of these stars. The model is based on
empirically-determined properties of solar activity. It
allows us to extrapolate to stars
of significantly higher and lower activity than seen on the present-day
Sun through its cycle. With it, we can, for example, gain insight into
stellar field patterns (including a possible formation mechanism for
polar starspots), as well as in the properties of coronal heating (helpful
in the identification of the quiescent coronal heating mechanism).
Lacking comprehensive theoretical understanding, the model's reliance
on empirical solar data means that the multitude of
processes involved are approximated to be independent of
rotation rate, activity level, and fundamental stellar parameters, or
-- where unavoidably necessary -- assumed
to simply scale with activity. An evaluation of the most
important processes involved guides a discussion of the limits of
the model, of the limitations in our knowledge, and of future needs.
Index Keywords:
Next: Ness
Up: Thursday Index
Up: Top Index
Manuscript submitted: 2001-Sep-27
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.