Outer atmospheres of cool stars. IV. A discussion of cool stellar wind models

Journal Article · Tue Jan 15 04:00:00 EST 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157655· OSTI ID:5461878

Haisch, B M; Linsky, J L; Basri, G S

We investigate possible wind models for late-type stars which appear not to have hot coronae and transition regions. Taking Arcturus as our prototypical star, we consider wind models with T> or approx. =20,000 K and search for solutions with mass loss rates approx.10/sup -9/ M/sub sun/ yr/sup -1/. Thermally driven models which are spherically symmetric or include widely diverging geometries predict mass loss rates orders of magnitude less than 10/sup -9/ M/sub sun/ yr/sup -1/. We find that the radiation pressure of L..cap alpha.. resonance scattering can exceed the force of gravity in the chromosphere and initiate a net outflow, but it is insufficient to sustain a wind. If an additional momentum input term, such as Alfven wave pressure, is also present, then L..cap alpha.. radiation pressure may play a crucial role in turning on strong winds in stars like Arcturus by producing a critical point in the chromosphere and a locally supersonic flow which the additional mechanism can further accelerate. We conclude that L..cap alpha.. radiation-pressure-initiated winds can occur in stars to the right of the Linsky-Haisch dividing line in the H-R diagram between stars with and without transition regions and presumably hot coronae, and that the existence of these winds may explain energetically the absence of hot coronae in these stars.

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado and National Bureau of Standards
• OSTI ID: 5461878
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 235:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
ATMOSPHERES
DIAGRAMS
DIFFERENTIAL EQUATIONS
EQUATIONS
EQUATIONS OF MOTION
FLUID FLOW
FLUID MECHANICS
GRAVITATION
HERTZSPRUNG-RUSSELL DIAGRAM
HYDRODYNAMICS
HYDROMAGNETIC WAVES
LYMAN LINES
MAGNETIC FIELDS
MATHEMATICAL MODELS
MECHANICS
RADIATION PRESSURE
SHOCK WAVES
STAR MODELS
STARS
STELLAR ATMOSPHERES
STELLAR RADIATION
STELLAR WINDS