Cool Stars 14 - Submitted Abstract # 29
This version created on 05 October 2006

Winds of Main-Sequence Stars:  Observational Limits and a Path to
Theoretical Prediction


Steven R. Cranmer, Harvard-Smithsonian Center for Astrophysics

It is notoriously difficult to measure the winds of solar-type stars.
Traditional spectroscopic and radio continuum techniques are sensitive
to mass loss rates at least two to three orders of magnitude stronger
than the Sun's relatively feeble wind.  Much has been done with these
methods to probe the more massive outflows of younger (T Tauri) and
older (giant, AGB, supergiant) cool stars, but the main sequence
remains terra incognita.  This presentation reviews the limits on
traditional diagnostics and outlines more recent ideas such as Lyman
alpha astrospheres and charge-exchange X-ray emission.  In addition,
there are hybrid constraints on mass loss rates that combine existing
observables and theoretical models.  The Sackmann/Boothroyd conjecture
of a more massive young Sun (and thus a much stronger ZAMS wind) is
one such idea that needs to be tested further.  Another set of ideas
involves a strong proposed coupling between coronal heating and
stellar mass loss rates, where the former is easier to measure in
stars down to solar-like values.  The combined modeling of stellar
coronae and stellar winds is developing rapidly, and it seems to be
approaching a level of development where the only remaining "free
parameters" involve the sub-photospheric convection.  This talk will
also summarize these theoretical efforts to predict the properties of
solar-type main-sequence winds.

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