Search Publications
Global Sausage Oscillation of Solar Flare Loops Detected by the Interface Region Imaging Spectrograph
Reeves, Katharine K.; Chen, Bin; He, Jiansen +4 more
An observation from the Interface Region Imaging Spectrograph reveals coherent oscillations in the loops of an M1.6 flare on 2015 March 12. Both the intensity and Doppler shift of Fe xxi 1354.08 Å show clear oscillations with a period of ∼25 s. Remarkably similar oscillations were also detected in the soft X-ray flux recorded by the Geostationary …
Hooked Flare Ribbons and Flux-rope-related QSL Footprints
Li, Hui; Aulanier, Guillaume; Schmieder, Brigitte +3 more
We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory/Atmospheric Imaging Assem…
Simultaneous IRIS and Hinode/EIS Observations and Modelling of the 2014 October 27 X2.0 Class Flare
Mason, H. E.; Golub, L.; Del Zanna, G. +5 more
We present a study of the X2-class flare which occurred on 2014 October 27 and was observed with the Interface Region Imaging Spectrograph (IRIS) and the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. Thanks to the high cadence and spatial resolution of the IRIS and EIS instruments, we are able to compare simultaneous observations o…
The Relation between Solar Eruption Topologies and Observed Flare Features. II. Dynamical Evolution
Pariat, E.; DeLuca, E. E.; McKillop, S. +4 more
A long-established goal of solar physics is to build understanding of solar eruptions and develop flare and coronal mass ejection (CME) forecasting models. In this paper, we continue our investigation of nonlinear forces free field (NLFFF) models by comparing topological properties of the solutions to the evolution of the flare ribbons. In particu…
Measurements of Non-thermal Line Widths in Solar Active Regions
Warren, Harry P.; Brooks, David H.
Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1-4 MK) o…
Chromospheric Condensation and Quasi-periodic Pulsations in a Circular-ribbon Flare
Li, D.; Zhang, Q. M.; Ning, Z. J.
In this paper, we report our multiwavelength observations of the C3.1 circular-ribbon flare SOL2015-10-16T10:20 in active region (AR) 12434. The flare consisted of a circular flare ribbon (CFR), an inner flare ribbon (IFR) inside it, and a pair of short parallel flare ribbons (PFRs). The PFRs located to the north of the IFR were most striking in t…
Observation of a Quasiperiodic Pulsation in Hard X-Ray, Radio, and Extreme-ultraviolet Wavelengths
Kumar, Pankaj; Cho, Kyung-Suk; Nakariakov, Valery M.
We present a multiwavelength analysis of a quasiperiodic pulsation (QPP) observed in the hard X-ray (HXR), radio, and extreme-ultraviolet (EUV) channels during an M1.9 flare that occurred on 2011 September 23-24. The nonthermal HXR emission in 25-50 keV observed by RHESSI shows five distinct impulsive peaks of decaying amplitude with a period of a…
High Spatial Resolution Fe XII Observations of Solar Active Regions
Testa, Paola; De Pontieu, Bart; Hansteen, Viggo
We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (∼0.33″). We find that by using appropriate observational strategies (I.e., long exposures, lossless compression), Fe xii emission can…
The Solar Internetwork. II. Flux Appearance and Disappearance Rates
Gošić, M.; Bellot Rubio, L. R.; Katsukawa, Y. +2 more
Small-scale internetwork magnetic fields are important ingredients of the quiet Sun. In this paper we analyze how they appear and disappear on the solar surface. Using high resolution Hinode magnetograms, we follow the evolution of individual magnetic elements in the interior of two supergranular cells at the disk center. From up to 38 hr of conti…
Observational Signatures of Coronal Loop Heating and Cooling Driven by Footpoint Shuffling
Velli, M.; Warren, H. P.; Ugarte-Urra, I. +4 more
The evolution of a coronal loop is studied by means of numerical simulations of the fully compressible three-dimensional magnetohydrodynamic equations using the HYPERION code. The footpoints of the loop magnetic field are advected by random motions. As a consequence, the magnetic field in the loop is energized and develops turbulent nonlinear dyna…