The association of aJ-burst with a solar jet

Abstract

Context. The Sun is an active star that produces large-scale energetic events such as solar flares and coronal mass ejections and numerous smaller-scale events such as solar jets. These events are often associated with accelerated particles that can cause emission at radio wavelengths. The reconfiguration of the solar magnetic field in the corona is believed to be the cause of the majority of solar energetic events and accelerated particles. Aims. Here, we investigate a bright J-burst that was associated with a solar jet and the possible emission mechanism causing these two phenomena. Methods. We used data from the Solar Dynamics Observatory (SDO) to observe a solar jet, and radio data from the Low Frequency Array (LOFAR) and the Nançay Radioheliograph (NRH) to observe a J-burst over a broad frequency range (33-173 MHz) on 9 July 2013 at ∼11:06 UT. Results. The J-burst showed fundamental and harmonic components and it was associated with a solar jet observed at extreme ultraviolet wavelengths with SDO. The solar jet occurred at a time and location coincident with the radio burst, in the northern hemisphere, and not inside a group of complex active regions in the southern hemisphere. The jet occurred in the negative polarity region of an area of bipolar plage. Newly emerged positive flux in this region appeared to be the trigger of the jet. Conclusions. Magnetic reconnection between the overlying coronal field lines and the newly emerged positive field lines is most likely the cause of the solar jet. Radio imaging provides a clear association between the jet and the J-burst which shows the path of the accelerated electrons. These electrons travelled from a region in the vicinity of the solar jet along closed magnetic field lines up to the top of a closed magnetic loop at a height of ∼360 Mm. Such small-scale complex eruptive events arising due to magnetic reconnection could facilitate accelerated electrons continuously to produce the large numbers of Type III bursts observed at low frequencies, in a similar way to the J-burst analysed here.

Solar Type J Radio Bursts and the Associated Coronal Loop

“…The animation shows an increase in brightness at the northern footpoint of the coronal loop, from which EUV jets are continuously injected into the loop. The series of type III bursts, seen in Figure 2(a), may be attributed to this brightening footpoint, which is consistent with previous studies on type III bursts (e.g., Aschwanden et al 1992;Aurass & Klein 1997;McCauley et al 2017;Morosan et al 2017).…”

“…For example, Yao et al (1997) gave the velocity (0.26-0.38 c) of energetic electrons exciting a U-shaped burst at 1.0-2.8 GHz, and Fernandes et al (2012) found the velocity to be 0.16-0.53c for a U-shaped burst in the frequency range 950-2500 MHz. Some type J, U, and N bursts have harmonic bands (Labrum & Stewart 1970;Aurass & Klein 1997;Dorovskyy et al 2015;Morosan et al 2017). Stewart (1974) pointed out that the frequency ratio of the second harmonic band to the fundamental is less than 2.…”

Unsupervised Generation of High Dynamic Range Solar Images: A Novel Algorithm for Self-calibration of Interferometry Data

“…These instruments are already producing interesting scientific results (e.g. Morosan et al 2014Morosan et al , 2015Tun Beltran et al 2015;Morosan et al 2016;Kontar et al 2017;Morosan et al 2017;McCauley et al 2017;Suresh et al 2017;Cairns et al 2018;Sharma et al 2018;Mohan et al 2018;Zucca et al 2018). The advent of Atacama Large millimeter and sub-millimeter Array, with its large number of elements, is leading to a large improvement in the quality of solar snapshot images at mm wavelengths (e.g.…”

Evidence for Super-Alfvénic Oscillations in Solar Type III Radio Burst Sources

“…There are now many studies in the literature exploiting this comparatively new capability to study various aspects of solar radio bursts and the ambient corona (e.g. Oberoi et al 2011;Chen et al 2013;Morosan et al 2014Morosan et al , 2017Mohan & Oberoi 2017;McCauley et al 2018McCauley et al , 2017Cairns et al 2018). SS imaging studies of sources of type III emission can provide a comprehensive spectro-temporal evolutionary picture of all observable properties, namely morphology, intensity and sky location.…”