University of Maryland
Computer & Space Science Building, Room 2400
4:30 PM Monday, 23 October
Coffee, Tea & Cookies 4:00-4:30 PM
Gordon D. Holman
NASA GSFC
Results from X-Ray Observations of Solar Flares with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
Observations of solar flares in X-rays
provide the most direct information about the hottest plasma and the
energetic electrons accelerated in flares. The Ramaty High Energy Solar
Spectroscopic Imager (RHESSI) has observed over 20,000 solar flares in
X-rays since its launch in February of 2002. RHESSI observes the full
Sun at X-ray energies from as low as 3 keV to gamma-ray energies as
high as 17 MeV with a spectral resolution on the order of 1 keV. It
also provides images in arbitrary bands within this energy range with
spatial resolution as good as 3 seconds of arc. Full images are
typically produced every 4 seconds, although higher time resolution is
possible. This unprecedented combination of spatial, spectral, and
temporal resolution, spectral range and flexibility has led to
fundamental advances in our understanding of flares.
I will show RHESSI
and coordinated observations that confirm coronal magnetic reconnection
models for eruptive flares and coronal mass ejections, but also present
new puzzles for these models. I will demonstrate how the analysis of
RHESSI spectra has led to a better determination of the energy flux and
total energy in accelerated electrons, and of the energy in the hot,
thermal flare plasma. I will discuss how these energies compare with
each other and with the energy contained in other flare-related
phenomena such as interplanetary particles and coronal mass ejections.
Sponsored by: Department of Physics
and the Institute for Physical Science and Technology, University of Maryland. For information
call John Paquette at (301) 405-6237 or go to the UMD Space Physics group seminar web site.
For free parking please park in lot DD or anywhere on levels 1-2 in lot B (the big parking garage) after 4:00 pm.
Make sure that you park in a spot WITHOUT a parking meter. More parking information is at the seminar website.