Solar Observations 2 J Todd Hoeksema Stanford University

Solar Observations 2 J. Todd Hoeksema Stanford University

SOHO/MDI Magnetic Rotation May 1998

Three-Temperature Solar Rotation

Solar X-Ray Cycle

Stellar Cycles

Hinode G-Band Image of Stellar Surface

Flare Helioseismology Sounds Of Modes

SOLAR SCIENCE - Nov 07, 2006 Monster Stellar Flare Dwarfs All Others Scientists using NASA's Swift satellite have spotted a stellar flare on a nearby star so powerful that, had it been from our sun, it would have triggered a mass extinction on Earth. The flare was perhaps the most energetic magnetic stellar explosion ever detected. The flare was seen in December 2005 on a star slightly less massive than the sun, in a two-star system called II Pegasi in the constellation Pegasus. It was about a hundred million times more energetic than the sun's typical solar flare, releasing energy equivalent to about 50 million trillion atomic bombs. Fortunately, our sun is now a stable star that doesn't produce such powerful flares. And II Pegasi is at a safe distance of about 135 light-years from Earth. Yet in detecting this brilliant flare, scientists obtained direct observational evidence that stellar flares on other stars involve particle acceleration, just like on our sun. Rachel Osten of University of Maryland NASA Goddard Space Flight Center in Greenbelt, Md. , presents this finding today at the Cool Stars 14 meeting in Pasadena, Calif. , , This is a real image of a typical solar flare from our sun, from September 2005, captured in the X-ray waveband by NASA's TRACE satellite. Note the bright magnetic loops of matter. The twisting and reconnecting of these loops initiate the flare. NASA's Swift satellite detected a similar flare from a star system called II Pegasi 135 light-years from Earth. . . except it was one hundred million times more energetic than the sun's typical solar flare. Had it been from our sun, it would have triggered a mass extinction on Earth. The II Pegasi flare was too distant (fortunately) to image in detail. Credit: NASA/LMSAL