Astronomy and Astrophysics – Astronomy
Scientific paper
May 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004aas...204.4707s&link_type=abstract
American Astronomical Society Meeting 204, #47.07; Bulletin of the American Astronomical Society, Vol. 36, p.737
Astronomy and Astrophysics
Astronomy
Scientific paper
The 2004 Oct. 28 and Nov. 2 flares were the most prolific emitters of nuclear gamma-rays observed by RHESSI, with measured fluences >1900 and ˜ 900 γ cm-2, respectively. The Oct. 28 event was the brightest gamma-ray flare detected in over 20 years. We discuss measurements of nuclear de-excitation lines from Fe, Mg, Ne, Si, C, and O that provide information on the directionality of accelerated particles and the composition of the flare plasma where they interact. A strong narrow γ -ray line is emitted when neutrons produced by similar interactions are captured in the photosphere by H. We have imaged this capture-line and resolved a double source with components located on opposite sides of the post-flare arcade observed by TRACE in the Oct. 28 flare. We also discuss RHESSI images of the Oct. 29 and Nov. 2 flares. The positron-electron annihilation line and continuum provide information on the temperature and density near where the ions interact. The 511 keV line observed by RHESSI in the 2002 July 23 flare had a Gaussian width of 8.1 ± 1.1 keV FWHM, consistent with ˜ (4-7) × 105K, if the broadening is thermal. The annihilation lines observed early in the Oct. 28 and Nov. 2 flares are also broadened: ˜ 5.5 and ˜ 6.5 keV FWHM, respectively. The lack of a strong positronium continuum suggests that the lines are broadened thermally in an ionized medium at ˜ 1014 H cm-3. The line narrows significantly to ˜ 1 keV later in the Oct. 28 flare, suggestive of a significant drop in temperature. This work was supported by NASA DPR W19746/10049 at NRL and by NAS 5-98033 at UCB and GSFC.
Hurford Gordon J.
Lin Robert P.
Murphy Ronald J.
Schwartz Richard A.
Share Gerald H.
No associations
LandOfFree
Gamma-Ray Spectroscopy & Imaging - What We Learn About Flares From High-Energy Ions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Gamma-Ray Spectroscopy & Imaging - What We Learn About Flares From High-Energy Ions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gamma-Ray Spectroscopy & Imaging - What We Learn About Flares From High-Energy Ions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1173824