UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

The origin of quasi-periodicities during circular ribbon flares

Kashapova, LK; Kupriyanova, EG; Xu, Z; Reid, HAS; Kolotkov, DY; (2020) The origin of quasi-periodicities during circular ribbon flares. Astronomy & Astrophysics , 642 , Article A195. 10.1051/0004-6361/201833947. Green open access

[thumbnail of Reid_aa33947-18.pdf]
Reid_aa33947-18.pdf - Published Version

Download (2MB) | Preview


Context. Solar flares with a fan-spine magnetic topology are able to form circular ribbons. A previous study based on Hα line observations of the solar flares on 5 March 2014 revealed a uniform and continuous rotation of the magnetic fan-spine. A preliminary analysis of the flare time profiles revealed quasi-periodic pulsations (QPPs) with similar properties in hard X-rays, Hα, and microwaves. / Aims. In this work, we address the question of whether the observed periodicities are related to periodic acceleration of electrons or plasma heating. / Methods. We analysed QPPs in the Hα emission from the centre of the fan (inner ribbon R1), a circular ribbon (R2), a remote source (R3), and an elongated ribbon (R4) located between R2 and R3. We used methods of correlation, Fourier, wavelet, and empirical mode decomposition. We compared the QPPs in Hα emission with those in microwave and X-ray emission. / Results. We found multi-wavelength QPPs with periods around 150 s, 125 s, and 190 s. The 150 s period is seen to co-exist in Hα, hard X-rays, and microwave emissions, which allowed us to connect it with flare kernels R1 and R2. These kernels spatially coincide with the site of the primary flare energy release. The 125 s period is found in the Hα emission of the elongated ribbon R4 and the microwave emission at 5.7 GHz during the decay phase. The 190 s period is present in the emission during all flare phases in the Hα emission of both the remote source, R3, and the elongated ribbon, R4, in soft X-rays and in microwaves at 4–8 GHz. / Conclusions. We connected the dominant 150 s QPPs with the slipping reconnection mechanism occurring in the fan. We suggested that the period of 125 s in the elongated ribbon can be caused by a kink oscillation of the outer spine, connecting the primary reconnection site with the remote footpoint. The period of 190 s is associated with the three-minute sunspot oscillations.

Type: Article
Title: The origin of quasi-periodicities during circular ribbon flares
Open access status: An open access version is available from UCL Discovery
DOI: 10.1051/0004-6361/201833947
Publisher version: https://doi.org/10.1051/0004-6361/201833947
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Sun: flares / acceleration of particles / magnetic reconnection / Sun: radio radiation / Sun: X-rays, gamma rays / Sun: chromosphere
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10113457
Downloads since deposit
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item