A note on the magnetic field strengths on the surfaces of cool dwarfs

Abstract

Various techniques have been used to detect and measure magnetic fields in cool dwarf stars. In the case of one of the stars discussed by Linsky and Gary (1983), it is shown that if the emission is optically thick gyrosynchrotron, then the fields at the surface of the star are in the range from 10 to 20 kilogauss. These field strengths have been labeled 'unrealistic' by Linsky and Gary. In the present investigation, it is shown that currently available observational data do not exclude the possibility that fields with field strengths in the range from 10 to 20 kilogauss exist in dark spots on the surfaces of cool dwarf stars. Thus, contrary to the statement of Linsky and Gary, photospheric fields in the 10-20 kilogauss range need not be 'unrealistic'.