Context. Quasi-periodic plasma jets are often ejected from the Sun into interplanetary space. The commonly observed signatures are day-long sequences of type III radio bursts.
Aims: The aim is to identify the source of quasi-periodic jets observed on 3 Aug. 2010 in the Sun's corona and in interplanetary space.
Methods: Images from the Solar Dynamics Observatory (SDO) at 211 Å are used to identify the solar source of the type III radio bursts seen in WIND/WAVES dynamic spectra. We analyse a 2.5 h period during which six strong bursts are seen. The radio signals are cross-correlated with emission from extreme ultraviolet (EUV) jets coming from the western side of a sunspot in AR 11092. The jets are further cross-correlated with brightening at a small site on the edge of the sunspot umbra, and the brightening with 3-min sunspot intensity oscillations.
Results: The radio bursts correlate very well with the EUV jets. The EUV jet emission also correlates well with brightening at what looks like their footpoint at the edge of the umbra. The jet emission lags the radio signals and the footpoint brightening by about 30 s because the EUV jets take time to develop. For 10-15 min after strong EUV jets are ejected, the footpoint brightens at roughly 3 min intervals. In both the EUV images and the extracted light curves, it looks as though the brightening is related to the 3-min sunspot oscillations, although the correlation coefficient is rather low. The only open field near the jets is rooted in the sunspot.
Conclusions: Active region EUV/X-ray jets and interplanetary electron streams originate on the edge of the sunspot umbra. They form along a current sheet between the sunspot open field and closed field connecting to underlying satellite flux. Sunspot running penumbral waves cause roughly 3-min jet footpoint brightening. The relationship between the waves and jets is less clear.
Astronomy and Astrophysics
- Pub Date:
- July 2011
- Sun: activity;
- Sun: oscillations;
- Sun: radio radiation;
- Sun: UV radiation;
- magnetic reconnection;
- Astrophysics - Solar and Stellar Astrophysics
- 4 pages, 7 figures, Accepted by A&