Acceleration and injection of highly relativistic electrons during the August 7, 1972, solar flare

Journal Article · Fri Nov 30 04:00:00 EST 1973 · Nature (London), v. 246, no. 5430, pp. 300-301

DOI:https://doi.org/10.1038/246300a0· OSTI ID:4383865

Maccagni, D; Perotti, F; Villa, G; Cherki, G; Raviart, A; Treguer, L

It is stated that the 3B flare of August 7, 1972 was one of the largest of the present solar cycle, and thanks to the favorable conditions for particle propagation and to the time of day it occurred, a large quantity of data is available. Highly relativistic electrons from the flare have been observed in outer space by spacecraft. The time profile of the onset of the flare electrons is shown graphically and the time history of relevant phenomena that occurred on August 7th is shown schematically. The GHz radio bursts and the hard x-ray emission are sure signs of relativistic electrons moving in the solar magnetic fields, and the magnetic field in which the electrons radiate must have been of the order of 1000 gauss. Several accelerations appear to have taken place during the approximates 10 min. rise time of the radio and x-ray bursts. each acceleration lasting less than 1 min. This multiple acceleration cannot, however, explain the time lag on the Earth between protons and electrons. If a very fine structure of the interplanetary magnetic field is not responsible for the delay in arrival time of the first electrons, these must spend 5 to 10 min. after acceleration in the solar corona, in a region where radiation energy losses are not large. This implies that since the times of acceleration and of injection into interplanetary space may not always coincide care must be taken in applying propagation theories to solar panticle events. Furthermore, if the time delay in the onset of the relativistic electrons means that they spend this time in the solar corona, not only their injection time but also the longitude of injection can be different from that of the protons. (UK)

• Research Organization: Consiglo Nazionale delle Ricerche, Milan
• NSA Number: NSA-29-016575
• OSTI ID: 4383865
• Journal Information: Nature (London), v. 246, no. 5430, pp. 300-301, Journal Name: Nature (London), v. 246, no. 5430, pp. 300-301; ISSN NATUA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

ACCELERATION
INTERPLANETARY SPACE
MAGNETIC FIELDS
N56400* --Physics (Astrophysics & Cosmology)--Solar Phenomena
RADIOWAVE RADIATION
RELATIVISTIC RANGE
TIME DEPENDENCE
X RADIATION