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Title: Magnetohydrostatic equilibrium in starspots: dependences on color (Teff) and surface gravity (g)
Authors: Rajaguru, S. P
Hasan, S. S
Keywords: Sun: magnetic fields;Sunspots; stars;Magnetic fields;Stars: spots;Stars: activity
Issue Date: Aug-2011
Publisher: Cambridge University Press
Citation: The Physics of Sun and Star Spots, Proceedings of the International Astronomical Union, IAU Symposium, Vol. 273, pp. 276-280
Series/Report no.: International Astronomical Union Symposium; No. 273
Abstract: Temperature contrasts and magnetic field strengths of sunspot umbrae broadly follow the thermal-magnetic relationship obtained from magnetohydrostatic equilibrium. Using a compilation of recent observations, especially in molecular bands, of temperature contrasts of starspots in cool stars, and a grid of Kurucz stellar model atmospheres constructed to cover layers of sub-surface convection zone, we examine how the above relationship scales with effective temperature (Teff), surface gravity g and the associated changes in opacity of stellar photospheric gas. We calculate expected field strengths in starpots and find that a given relative reduction in temperatures (or the same darkness contrasts) yield increasing field strengths against decreasing Teff due to a combination of pressure and opacity variations against Teff.
Description: Open Access
???metadata.dc.rights???: © International Astronomical Union
Appears in Collections:IIAP Publications

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