Professor
Umran S. Inan
Winter
2002-2003
Date: Wednesday, January 15, 2003
Time: 4:15 PM – Refreshments at 4:00
Location: Bldg. 200, Rm. 013
Professor
Robert P. Lin
Physics Department and the Space Sciences
Laboratory,
University of California, Berkeley
The
Sun is the most powerful particle accelerator in the solar system, accelerating
ions up to tens of GeV and electrons to hundreds of MeV in both solar flares and
fast Coronal Mass Ejections (CMEs). Solar flares
are the most energetic explosions, releasing up to 10^32-10^33 ergs in 10-1000s. The accelerated ~10-100 keV electrons (and
sometimes >~1 MeV ions) appear
to contain >~10-50% of this energy, indicating that the particle acceleration and energy release processes are
intimately linked. The RHESSI (Ramaty High Energy Solar Spectroscopic Imager)
Small Explorer mission utilizes rotating modulation collimators and cooled
germanium detectors to provide the first high resolution imaging (~2
arcsec) and spectroscopy (~keV FWHM) of flare hard X-ray/gamma-ray
continuum and gamma-ray lines emitted by energetic electrons and ions,
respectively, at the Sun. I will present RHESSI hard X-ray imaging
spectroscopy of solar flares, and discuss the implications for particle
acceleration and energy release. In addition, I will present the first high
resolution spectroscopy and imaging of flare gamma-ray lines, the first
detection of continous solar emission and microflares in the 3-10 keV energy
range, and first detection of hard X-ray counterparts to solar type III radio
bursts.