Search Publications
Frequently Occurring Reconnection Jets from Sunspot Light Bridges
Solanki, Sami K.; Ni, Lei; Chen, Yajie +12 more
Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world’s largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line …
Investigating the Response of Loop Plasma to Nanoflare Heating Using RADYN Simulations
Reale, Fabio; De Pontieu, B.; Carlsson, M. +5 more
We present the results of 1D hydrodynamic simulations of coronal loops that are subject to nanoflares, caused by either in situ thermal heating or nonthermal electron (NTE) beams. The synthesized intensity and Doppler shifts can be directly compared with Interface Region Imaging Spectrograph (IRIS) and Atmospheric Imaging Assembly (AIA) observatio…
Identifying Typical Mg II Flare Spectra Using Machine Learning
Krucker, Säm; Kleint, Lucia; Panos, Brandon +4 more
The Interface Region Imaging Spectrograph (IRIS) performs solar observations over a large range of atmospheric heights, including the chromosphere where the majority of flare energy is dissipated. The strong Mg II h&k spectral lines are capable of providing excellent atmospheric diagnostics, but have not been fully utilized for flaring atmosph…
Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence
Chen, Yajie; Tian, Hui; Zhu, Xiaoshuai +3 more
On 2016 September 20, the Interface Region Imaging Spectrograph observed an active region during its earliest emerging phase for almost 7 hr. The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory observed continuous emergence of small-scale magnetic bipoles with a rate of ∼1016 Mx s-1. The emergence of …
Two Episodes of Magnetic Reconnections during a Confined Circular-ribbon Flare
Hou, Yijun; Li, Ting; Yang, Shuhong +2 more
We analyze a unique event with an M1.8 confined circular-ribbon flare on 2016 February 13, with successive formations of two circular ribbons at the same location. The flare had two distinct phases of UV and extreme ultraviolet emissions with an interval of about 270 s, of which the second peak was energetically more important. The first episode w…
IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation
Tiwari, Sanjiv K.; De Pontieu, Bart; Panesar, Navdeep K. +3 more
Recent observations show that the buildup and triggering of minifilament eruptions that drive coronal jets result from magnetic flux cancelation at the neutral line between merging majority- and minority-polarity magnetic flux patches. We investigate the magnetic setting of 10 on-disk small-scale UV/EUV jets (jetlets, smaller than coronal X-ray je…
Transverse Wave Induced Kelvin-Helmholtz Rolls in Spicules
De Pontieu, B.; Schmit, D.; Pereira, T. M. D. +2 more
In addition to their jet-like dynamic behavior, spicules usually exhibit strong transverse speeds, multi-stranded structure, and heating from chromospheric to transition region temperatures. In this work we first analyze Hinode and IRIS observations of spicules and find different behaviors in terms of their Doppler velocity evolution and collectiv…
Impact of Type II Spicules in the Corona: Simulations and Synthetic Observables
Martínez-Sykora, Juan; De Pontieu, Bart; Carlsson, Mats +2 more
The role of type II spicules in the corona has been a much debated topic in recent years. This paper aims to shed light on the impact of type II spicules in the corona using novel 2.5D radiative MHD simulations, including ion-neutral interaction effects with the Bifrost code. We find that the formation of simulated type II spicules, driven by the …
Pre-eruptive Magnetic Reconnection within a Multi-flux-rope System in the Solar Corona
Wang, Haimin; Wang, Yuming; Shen, Chenglong +2 more
The solar corona is frequently disrupted by coronal mass ejections (CMEs), whose core structure is believed to be a flux rope made of helical magnetic field. This has become a “standard” picture; though, it remains elusive how the flux rope forms and evolves toward eruption. While one-third of the ejecta passing through spacecraft demonstrate a fl…
Multi-episode Chromospheric Evaporation Observed in a Solar Flare
Tian, H.; Chen, N. -H.
With observations of the Interface Region Imaging Spectrograph (IRIS), we study chromospheric heating and evaporation during an M1.6 flare SOL2015-03-12T11:50. At the flare ribbons, the Mg II 2791.59 Å line shows quasi-periodic short-duration red-wing enhancement, which is likely related to repetitive chromospheric condensation as a result of epis…