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Record Details

Record 56 of 3503
Solar Type II Radio Bursts and IP Type II Events
External Online Source: doi:10.1086/428820
Author and Affiliation:
Cane, H. V.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Erickson, W. C.(Tasmania Univ., School of Mathematics, Hobart, Australia)
Abstract: We have examined radio data from the WAVES experiment on the Wind spacecraft in conjunction with ground-based data in order to investigate the relationship between the shocks responsible for metric type II radio bursts and the shocks in front of coronal mass ejections (CMEs). The bow shocks of fast, large CMEs are strong interplanetary (IP) shocks, and the associated radio emissions often consist of single broad bands starting below approx. 4 MHz; such emissions were previously called IP type II events. In contrast, metric type II bursts are usually narrowbanded and display two harmonically related bands. In addition to displaying complete dynamic spectra for a number of events, we also analyze the 135 WAVES 1 - 14 MHz slow-drift time periods in 2001-2003. We find that most of the periods contain multiple phenomena, which we divide into three groups: metric type II extensions, IP type II events, and blobs and bands. About half of the WAVES listings include probable extensions of metric type II radio bursts, but in more than half of these events, there were also other slow-drift features. In the 3 yr study period, there were 31 IP type II events; these were associated with the very fastest CMEs. The most common form of activity in the WAVES events, blobs and bands in the frequency range between 1 and 8 MHz, fall below an envelope consistent with the early signatures of an IP type II event. However, most of this activity lasts only a few tens of minutes, whereas IP type II events last for many hours. In this study we find many examples in the radio data of two shock-like phenomena with different characteristics that occur simultaneously in the metric and decametric/hectometric bands, and no clear example of a metric type II burst that extends continuously down in frequency to become an IP type II event. The simplest interpretation is that metric type II bursts, unlike IP type II events, are not caused by shocks driven in front of CMEs.
Publication Date: Apr 20, 2005
Document ID:
20050180332
(Acquired Jun 21, 2005)
Subject Category: SOLAR PHYSICS
Document Type: Journal Article
Publication Information: Astrophysical Journal; p. 1180-1194; Volume 623
Publisher Information: American Astronautical Society, United States
Contract/Grant/Task Num: NSF ATM-02-07221
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD, United States
National Science Foundation; Arlington, VA, United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 15p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: SOLAR RADIO BURSTS; RADIO ASTRONOMY; SHOCK WAVES; CORONAL MASS EJECTION; SIGNATURES; PARTICLE ACCELERATION
Availability Source: Other Sources
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