Search Publications
Recovering Thermodynamics from Spectral Profiles observed by IRIS: A Machine and Deep Learning Approach
De Pontieu, Bart; Gošić, Milan; Sainz Dalda, Alberto +1 more
Inversion codes allow the reconstruction of a model atmosphere from observations. With the inclusion of optically thick lines that form in the solar chromosphere, such modeling is computationally very expensive because a non-LTE evaluation of the radiation field is required. In this study, we combine the results provided by these traditional metho…
SI IV Resonance Line Emission during Solar Flares: Non-LTE, Nonequilibrium, Radiation Transfer Simulations
Kerr, Graham S.; Carlsson, Mats; Young, Peter R. +2 more
The Interface Region Imaging Spectrograph routinely observes the Si IV resonance lines. When analyzing quiescent observations of these lines, it has typically been assumed that they form under optically thin conditions. This is likely valid for the quiescent Sun, but this assumption has also been applied to the more extreme flaring scenario. We us…
Solar Chromospheric Temperature Diagnostics: A Joint ALMA-Hα Analysis
Cranmer, Steven R.; Reardon, Kevin P.; Uitenbroek, Han +4 more
We present the first high-resolution, simultaneous observations of the solar chromosphere in the optical and millimeter wavelength ranges, obtained with the Atacama Large Millimeter Array (ALMA) and the Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope. In this paper we concentrate on the comparison between the brightness temp…
Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO
Tiwari, Sanjiv K.; Golub, Leon; Winebarger, Amy R. +14 more
The second Hi-C flight (Hi-C 2.1) provided unprecedentedly high spatial and temporal resolution (∼250 km, 4.4 s) coronal EUV images of Fe IX/X emission at 172 Å of AR 12712 on 2018 May 29, during 18:56:21-19:01:56 UT. Three morphologically different types (I: dot-like; II: loop-like; III: surge/jet-like) of fine-scale sudden-brightening events (ti…
Flame-like Ellerman Bombs and Their Connection to Solar Ultraviolet Bursts
Chen, Yajie; Cao, Wenda; Wang, Haimin +6 more
Ellerman bombs (EBs) are small-scale intense brightenings in Hα wing images, which are generally believed to be signatures of magnetic reconnection around the temperature minimum region of the solar atmosphere. They have a flame-like morphology when observed near the solar limb. Recent observations from the Interface Region Imaging Spectrograph (I…
First Detection of Plasmoids from Breakout Reconnection on the Sun
Antiochos, Spiro K.; Kumar, Pankaj; DeVore, C. Richard +2 more
Transient collimated plasma ejections (jets) occur frequently throughout the solar corona, in active regions, quiet Sun, and coronal holes. Although magnetic reconnection is generally agreed to be the mechanism of energy release in jets, the factors that dictate the location and rate of reconnection remain unclear. Our previous studies demonstrate…
Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar Magnetic Network Lanes
Tiwari, Sanjiv K.; Winebarger, Amy R.; Warren, Harry P. +15 more
We present high-resolution, high-cadence observations of six, fine-scale, on-disk jet-like events observed by the High-resolution Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We combine the Hi-C 2.1 images with images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and the Interface Region Imaging S…
Modeling Mg II h, k and Triplet Lines at Solar Flare Ribbons
Kowalski, Adam F.; Carlsson, Mats; Tian, Hui +3 more
Observations from the Interface Region Imaging Spectrograph often reveal significantly broadened and non-reversed profiles of the Mg II h, k and triplet lines at flare ribbons. To understand the formation of these optically thick Mg II lines, we perform plane-parallel radiative hydrodynamics modeling with the RADYN code, and then recalculate the M…
Can the Superposition of Evaporative Flows Explain Broad Fe XXI Profiles during Solar Flares?
Polito, Vanessa; Testa, Paola; De Pontieu, Bart
The observation of the high-temperature (≳10 MK) Fe XXI 1354.1 Å line with the Interface Region Imaging Spectrograph has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resol…
Subarcsecond Blobs in Flare-related Coronal Jets
Zhang, Q. M.; Ni, L.
In this paper, we report multiwavelength observations of subarcsecond blobs in coronal jets. In AR 12149, a C5.5 circular-ribbon flare occurred at ∼04:55 UT on 2014 August 24, which consisted of a discrete circular ribbon and a short inner ribbon inside. Two jets (jet1 and jet2) were related to the flare. Jet1 appeared first and experienced untwis…