SphinX MEASUREMENTS OF THE 2009 SOLAR MINIMUM X-RAY EMISSION

Abstract

The SphinX X-ray spectrophotometer on the CORONAS-PHOTON spacecraft measured\nsoft X-ray emission in the 1-15 keV energy range during the deep solar minimum\nof 2009 with a sensitivity much greater than GOES. Several intervals are\nidentified when the X-ray flux was exceptionally low, and the flux and solar\nX-ray luminosity are estimated. Spectral fits to the emission at these times\ngive temperatures of 1.7-1.9 MK and emission measures between 4 x 10^47 cm^-3\nand 1.1 x 10^48 cm^-3. Comparing SphinX emission with that from the Hinode\nX-ray Telescope, we deduce that most of the emission is from general coronal\nstructures rather than confined features like bright points. For one of 27\nintervals of exceptionally low activity identified in the SphinX data, the\nSun's X-ray luminosity in an energy range roughly extrapolated to that of ROSAT\n(0.1-2.4 keV) was less than most nearby K and M dwarfs.\n