Type III bursts observed simultaneously by Wind and Ulysses
Abstract
We consider a period of five months when Ulysses was passing behind the Sun as viewed from Wind and measure the low frequency cutoffs flo and the local plasma frequency fp for 303 bursts seen by one, the other, or both spacecraft. The preliminary results are: 1) 68% of the bursts were seen on dynamic spectra of both spacecraft. 2) Only about half of the bursts were simultaneously detected when Ulysses was nearly directly behind the Sun and within 20° of the ecliptic, while 80% were detected at other times during the period of study. 3) The distribution of cutoffs is independent of fp at the spacecraft, and is statistically the same at Wind and Ulysses. 4) The correlation coefficient of flo at Wind and Ulysses is 0.51, with many bursts (28%) having the same flo at the two spacecraft to within a factor of 1.12 and 50% having the same flo to within a factor of 1.4; for the others flo differs by up to a factor of 5. We conclude that, for many bursts, the existence of an intrisic cutoff to the radiation mechanism seems certain, but for others propagation effects surely play a role.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- May 1996
- DOI:
- 10.1029/96GL01353
- Bibcode:
- 1996GeoRL..23.1203D
- Keywords:
-
- Solar Physics;
- Astrophysics;
- and Astronomy: Radio emissions;
- Space Plasma Physics: Radiation processes;
- Space Plasma Physics: Wave/particle interactions