Magnetic fields, convection and solar luminosity variability

Abstract

Model calculations universally indicate that heat transport from the solar interior is almost entirely by convection in the outer envelope. Spiegel and Weiss¹ have recently discussed how magnetic fields can intrude into this envelope to affect convection and thus introduce transients into the Sun's luminosity. I demonstrate here from Fourier transform spectrometer observations of Fraunhofer line asymmetry that granular convection is retarded in the presence of surface magnetism. I then present full disk observations which suggest a lessening of convection over the past 5 yr. As this time interval coincides with the rise from a minimum to a maximum of solar activity, with the presumed injection of new magnetic flux from the interior, the resolved disk and full disk observations are consistent. Finally I note the continued temporal decrease in the spectroscopic temperature of the low photosphere and consider how a change of convection and the lowering temperature may be related.