Homologous flaring activity over a sunspot light bridge in an emerging active region
arXiv:2012.07454 · doi:10.3847/2041-8213/abd478
Abstract
Sunspot light bridges are known to exhibit a variety of dynamic and persistent phenomena such as surges, small-scale jets etc. in the chromosphere and transition region. While it has generally been proposed that magnetic reconnection is responsible for this small-scale dynamism, persistent flaring activity lasting several hours from the same spatial location on a sunspot light bridge, has rarely been reported. We combine observations from the Atmospheric Imaging Assembly and the Helioseismic Magnetic Imager on board the Solar Dynamics Observatory to investigate homologous flaring activity over a small sunspot light bridge in an emerging flux region. The homologous flares all produced broad, collimated jets, including a B6.4 class flare. The jets rise at a speed of about 200 km/s, reach projected heights of about 98 Mm, and emerge from the same spatial location for nearly 14 hrs, after which they cease completely. A non-linear force free extrapolation of the photospheric magnetic field shows a low-lying flux rope connecting the light bridge to a remote opposite-polarity network. The persistent flares occur as a result of the rapid horizontal motion of the leading sunspot that causes the relatively vertical magnetic fields in the adjacent umbra to reconnect with the low-lying flux rope in the light bridge. Our results indicate that the flaring ceases once the flux rope has lost sufficient twist through repeated reconnections.
arXiv commentAccepted for publication in The Astrophysical Journal Letters, 8 pages, 5 figures, 1 animation
References in corpus (21)
- The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches
- Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
- Nonlinear force-free modeling of the solar coronal magnetic field
- Fine structure, magnetic field and heating of sunspot penumbrae
- How to optimize nonlinear force-free coronal magnetic field extrapolations from SDO/HMI vector magnetograms?
- Plasma Ejections from a Light Bridge in a Sunspot Umbra
- Frequently Occurring Reconnection Jets from Sunspot Light Bridges
- Light Bridge in a Developing Active Region. I. Observation of Light Bridge and its Dynamic Activity Phenomena
- Fan-shaped jets above the light bridge of a sunspot driven by reconnection
- Supersonic Downflows in a Sunspot Light Bridge
- Small-scale chromospheric jets above a sunspot light bridge
- Upflows in the central dark lane of sunspot light bridges
- Surge-like oscillations above sunspot light bridges driven by magnetoacoustic shocks
- Triggering an eruptive flare by emerging flux in a solar active-region complex
- Sunspot splitting triggering an eruptive flare
- Analysis of a Fragmenting Sunspot using Hinode Observations
- Chromospheric Plasma Ejections in a Light Bridge of a Sunspot
- Signatures of magnetic reconnection at the footpoints of fan shape jets on a light bridge driven by photospheric convective motions
- The formation of an atypical sunspot light bridge as a result of large-scale flux emergence
- Small-scale magnetic and velocity inhomogeneities in a sunspot light bridge
- Three-minute Sunspot Oscillations Driven by Magnetic Reconnection in a Light Bridge