Source regions of the type II radio burst observed during a CME–CME interaction on 2013 May 22
by P. Mäkelä et al.*

2016-12-06 3,063 views

Occasionally the Sun ejects a pair of magnetized plasma clouds, called coronal mass ejections (CMEs), roughly into the same propagation direction in closely timed sequence. If the second CME is faster than the first one, the CMEs could either just slip through each other or they could collide and interact, when the following CME catches up the preceding one. The possibility of the CME-CME interaction was first suggested by Gopalswamy […]

Fragmented radio emission reveals a shock passing through solar active region loops
by Silja Pohjolainen, Jens Pomoell and Rami Vainio

2008-09-02 1,022 views

Shocks and type II bursts Radio type II bursts are observed in association with flares and coronal mass ejections (CMEs). Metric type II bursts can be observed in dynamic radio spectra as slowly drifting emission lanes, with drift rates approximately 0.1 — 1.0 MHz/s. The start frequency of metric type II bursts is usually at about 100 — 200 MHz. The mechanism behind the bursts is generally assumed to be […]

A New Wind/WAVES Type II Burst Catalog Available Online
by Nat Gopalswamy

2007-11-22 298 views

The CDAW Data Center announces the availability of a new catalog of type II radio bursts detected by the Radio and Plasma Waves (WAVES) experiment on board the Wind spacecraft and the associated coronal mass ejections (CMEs) observed by the Solar and Heliospheric Observatory (SOHO). The catalog is available at http://cdaw.gsfc.nasa.gov/CME_list/radio/waves_type2.html The catalog also contains information on the associated flares (X-ray importance and NOAA active region number). The CME sources […]

Coronal shock waves: tracking down the drivers for radio emission
by Silja Pohjolainen

2006-09-21 158 views

In the solar corona, shocks are formed when the speed of a disturbance exceeds the local magnetosonic (Alfvén) speed. At low atmospheric heights, above high-density active regions, the Alfvén velocity can drop down to a few hundred km/s, but it then rises steadily to a global maximum of about 1000 km/s near the heliocentric height of 3.5 R (see calculations in Warmuth & Mann 2005). At heights above 1.5 R […]

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