AAS 204th Meeting, June 2004
Session 25 The UV/Optical Universe at Ulta-High Angular Resolution
Special Session, Monday, May 31, 2004, 2:00-3:30pm, 707/709

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[25.01] Stellar activity and its impact on life in the universe

C.J. Schrijver (Lockheed Martin Advanced Technology Center, Palo Alto, CA)

Magnetic fields play a key role in the formation of stars and, likely, their planetary systems. The strong coronal emission and stellar wind that are powered by the intense field characteristic of a star's early years impact the planetary magnetospheres and atmospheres, and may play a role in the formation of molecules essential to life. Magnetic fields continue to play a role even in a star as old as our Sun, as we experience when space weather fronts affect our communication and navigation technologies or endanger astronauts. Longer term variations continue to influence planetary climates, leading on the earth to periods of above average temperature, as in the Grand Maxima, and to periods of cooler mean global temperatures, as in the Maunder Minimum. The stellar magnetic field is generated in the interior of a star like the Sun by a process that we refer to as the dynamo. The functioning of a nonlinear astrophysical dynamo remains shrouded in mystery, even though we know that rotation and convection are the most important ingredients. This is in part because at present we can study only one stellar dynamo in adequate detail, namely that of our Sun. In this talk, I explore: 1) the impacts of magnetic fields on stars and their environments and 2) how we can expect to achieve an understanding of the dynamo process by observing its functioning in distant stars of different physical properties.

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