TESTING A PREDICTIVE THEORETICAL MODEL FOR THE MASS LOSS RATES OF COOL STARS
By S. Cranmer, S. Saar. 2011
217 citations recorded by the source corpus.
The basic mechanisms responsible for producing winds from cool, late-type stars are still largely unknown. We take inspiration from recent progress in understanding solar wind acceleration to develop a physically motivated model of the time-steady mass loss rates of cool main-sequence stars and evolved giants. This model follows the energy flux of magnetohydrodynamic turbulence from a subsurface convection zone to its eventual dissipation and escape through open magnetic flux tubes. We show how Alfvén waves and turbulence can produce winds in either a hot corona or a cool extended chromosphere, and we specify the conditions that determine whether or not coronal heating occurs. These models do not utilize arbitrary normalization factors, but instead predict the mass loss rate directly from a star's fundamental properties. We take account of stellar magnetic activity by extending standard age-activity-rotation indicators to include the evolution of the filling factor of strong photospheric magnetic fields. We compared the predicted mass loss rates with observed values for 47 stars and found significantly better agreement than was obtained from the popular scaling laws of Reimers, Schröder, and Cuntz. The algorithm used to compute cool-star mass loss rates is provided as a self-contained and efficient computer code. We anticipate that the results from this kind of model can be incorporated straightforwardly into stellar evolution calculations and population synthesis techniques.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/937a873a9e5463036821274dfba39e1caf9eca43
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Citations in the corpus
- THE MASS-DEPENDENCE OF ANGULAR MOMENTUM EVOLUTION IN SUN-LIKE STARS (2014, methodology): “…progress in measurements of mass-loss rates of sun-like stars (Wood et al. 2005), theoretical predictions of wind properties (Suzuki et al. 2012; Cranmer & Saar 2011), mapping of surface magnetic fields (Donati & Landstreet 2009), and dynamo models (Miesch & Toomre 2009; Brun et al. 2014), we…”
- Stellar winds on the main-sequence - II. The evolution of rotation and winds (2015, methodology): “The Cranmer & Saar (2011b) model predicts mass loss rates that are a factor of a few higher than the mass loss rates that we predict.”
- Origins of the Ambient Solar Wind: Implications for Space Weather (2017, background): “ted by the still-unidentified source of coronal heating, and F cond is the energy flux conducted back down to the chromosphere (see also Hammer 1982; Hansteen and Leer 1995; Schwadron and McComas 2003; Cranmer and Saar 2011). The equation above neglects enthalpy fluxes and radiative losses, both of whi”
- Improved angular momentum evolution model for solar-like stars II. Exploring the mass dependence (2015, unknown): “The evolution of the mean magnetic field B ∗ f ∗ as a function of stellar density, effective temperature, and angular velocity is taken from the model developed by Cranmer & Saar (2011).”
- Mass loss of stars on the asymptotic giant branch (2018, background): “…from Alvén waves seems to be a promising mechanism for driving the winds of red giants and possibly red supergiants (Airapetian et al. 2000, 2010; Cranmer and Saar 2011), but there is doubt if it extends to the typical stellar parameter regime of AGB stars, and especially to the cooler part of…”
- Improved angular momentum evolution model for solar-like stars (2013, methodology): “However, the braking rate in the present models increases more steeply than Kawaler’s in the unsaturated regime (cf. Table 4) and the braking efficiency thus becomes larger than Kawaler’s as soon as the angular velocity exceeds the solar value.”