Search Publications
Spectroscopic Observations of Current Sheet Formation and Evolution
Warren, Harry P.; Doschek, George A.; Ugarte-Urra, Ignacio +3 more
We report on the structure and evolution of a current sheet that formed in the wake of an eruptive X8.3 flare observed at the west limb of the Sun on 2017 September 10. Using observations from the EUV Imaging Spectrometer (EIS) on Hinode and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory, we find that plasma in the curren…
Observations of Turbulent Magnetic Reconnection within a Solar Current Sheet
Cheng, X.; Ding, M. D.; Zhang, J. +4 more
Magnetic reconnection is a fundamental physical process in various astrophysical, space, and laboratory environments. Many pieces of evidence for magnetic reconnection have been uncovered. However, its specific processes that could be fragmented and turbulent have been short of direct observational evidence. Here, we present observations of a supe…
Determination of Differential Emission Measure from Solar Extreme Ultraviolet Images
Veronig, Astrid M.; Gan, Weiqun; Cheung, Mark C. M. +5 more
The Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) has been providing high-cadence, high-resolution, full-disk UV-visible/extreme ultraviolet (EUV) images since 2010, with the best time coverage among all the solar missions. A number of codes have been developed to extract plasma differential emission measures (DEM…
Magnetic Flux Cancelation as the Trigger of Solar Coronal Jets in Coronal Holes
Panesar, Navdeep K.; Moore, Ronald L.; Sterling, Alphonse C.
We investigate in detail the magnetic cause of minifilament eruptions that drive coronal-hole jets. We study 13 random on-disk coronal-hole jet eruptions, using high-resolution X-ray images from the Hinode/X-ray telescope(XRT), EUV images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), and magnetograms from the SDO/He…
Spectroscopic Observations of a Current Sheet in a Solar Flare
Feng, L.; Gan, W. Q.; Cheng, X. +6 more
The current sheet is believed to be the region of energy dissipation via magnetic reconnection in solar flares. However, its properties, for example, the dynamic process, are not fully understood. Here, we report a current sheet in a solar flare (SOL2017-09-10T16:06) that was clearly observed by the Atmospheric Imaging Assembly on board the Solar …
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…
Broad Non-Gaussian Fe XXIV Line Profiles in the Impulsive Phase of the 2017 September 10 X8.3-class Flare Observed by Hinode/EIS
Reeves, Katharine K.; Polito, Vanessa; Chen, Bin +4 more
We analyze the spectra of high-temperature Fe XXIV lines observed by the Hinode/Extreme-Ultraviolet Imaging Spectrometer (EIS) during the impulsive phase of the X8.3-class flare on 2017 September 10. The line profiles are broad, show pronounced wings, and clearly depart from a single-Gaussian shape. The lines can be well fitted with κ distribution…
Super-strong Magnetic Field in Sunspots
Okamoto, Takenori J.; Sakurai, Takashi
Sunspots are the most notable structure on the solar surface with strong magnetic fields. The field is generally strongest in a dark area (umbra), but sometimes stronger fields are found in non-dark regions, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Here we report clear e…
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…