Dartmouth Events

Abstract: The Sun is our paradigm for how stars evolve and behave. It is the only star whose surface is well-resolved in time and space. It is the only star which local helioseisomology can look into and through. It is also the only star with a well-resolved corona. One tool we use to study the Sun is the Solar Dynamics Observatory (SDO), a NASA satellite that has been returning data for six years. SDO focuses on the variations in the Sun caused by changes in the magnetic field generated by the convection zone. I will describe several SDO measurements that can be directly related to Sun-like stars. First are spectral irradiance measurements in extreme ultraviolet wavelengths that contribute to the loss of planetary atmospheres. Next are failed filament eruptions that fall back onto the surface as a form of accretion and views of comets never seen before SDO --- in the EUV where one comet simply disappears. Both of these phenomena show how cool plasma is heated by the solar atmosphere. Finally, I will describe some results about the solar convection zone and solar dynamo that constrain models of stellar convection zones. Please come and see how studying the Sun informs our knowledge of stars.

BIO: W. Dean Pesnell is the Project Scientist of the Solar Dynamics Observatory. He has published papers in research areas such as solar physics, variable stars, the Sun-Earth connection, quantum mechanics, and meteors in planetary atmospheres. He received his Ph.D. in 1983 from the University of Florida. After a post-doc at the University of Colorado and a visiting professorship at New Mexico State University, he became a contract research scientist at Goddard, eventually forming Nomad Research, Inc. in 1995. One series of contracts was to design the Living With a Star Geospace missions. He started work on SDO in 2004 and became the Project Scientist in 2005. His piano plot of 105 predictions of the amplitude of Solar Cycle 24 showed how far we have to go in understanding the Sun.