skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • High-resolution Observations of a Small-scale Cancellation Nanoflare: Supporting Evidence for the Cancellation Nanoflare Model

This content will become publicly available on May 15, 2026

Title: High-resolution Observations of a Small-scale Cancellation Nanoflare: Supporting Evidence for the Cancellation Nanoflare Model
Abstract An analytical cancellation nanoflare model has recently been established to show the fundamental role that ubiquitous small-scale cancellation nanoflares play in solar atmospheric heating. Although this model is well supported by simulations, observational evidence is needed to deepen our understanding of cancellation nanoflares. We present observations of a small-scale cancellation nanoflare event, analyzing its magnetic topology evolution, triggers, and physical parameters. Using coordinated observations from the Solar Dynamics Observatory and Goode Solar Telescope, we identify a photospheric flow-driven cancellation event with a flux cancellation rate of ∼1015Mx s−1and a heating rate of 8.7 × 106erg cm−2s−1. The event shows the characteristic transition fromπ-shaped to X-shaped magnetic configuration before the formation of a 2″ current sheet, closely matching model predictions. This event provides critical observational support for the cancellation nanoflare model and its role in solar atmospheric heating.  more » « less
Award ID(s):
2309939
PAR ID:
10598774
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
The Author(s). Published by the American Astronomical Society.
Date Published:
Journal Name:
The Astrophysical Journal Letters
Volume:
985
Issue:
1
ISSN:
2041-8205
Page Range / eLocation ID:
L11
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, The Astrophysical Journal)
    Abstract In this study, we analyze high-spatial-resolution (0.″24) magnetograms and high-spatial-resolution (0.″10) Hαoff-band (± 0.8 Å) images taken by the 1.6 m Goode Solar Telescope to investigate the magnetic properties associated with small-scale ejections in a coronal hole boundary region from a statistical perspective. With one and a half hours of optical observations under excellent seeing, we focus on the magnetic structure and evolution by tracking the magnetic features with the Southwest Automatic Magnetic Identification Suite (SWAMIS). The magnetic field at the studied coronal hole boundary is dominated by negative polarity with flux cancellations at the edges of the negative unipolar cluster. In a total of 1250 SWAMIS-detected magnetic cancellation events, ∼39% are located inside the coronal hole with an average flux cancellation rate of 2.0 × 1018Mx Mm−2hr−1, and ∼49% are located outside the coronal hole with an average flux cancellation rate of 8.8 × 1017Mx Mm−2hr−1. We estimated that the magnetic energy released due to flux cancellation inside the coronal hole is six times more than that outside the coronal hole. Flux cancellation accounts for ∼9.5% of the total disappearance of magnetic flux. Other forms of its disappearance are mainly due to fragmentation of unipolar clusters or merging with elements of the same polarity. We also observed a number of significant small-scale ejections associated with magnetic cancellations at the coronal hole boundary that have corresponding EUV brightenings. 
    more » « less
  2. ; ; ; ; ; (, The Astrophysical Journal Letters)
    Abstract We present the first joint high-resolution observations of small-scale EUV jets using Solar Orbiter (SolO)’s Extreme Ultraviolet Imager and High Resolution Imager (EUI/HRIEUV) and Hαimaging from the Visible Imaging Spectrometer installed on the 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory. These jets occurred on 2022 October 29 around 19:10 UT in a quiet Sun region, and their main axis aligns with the overarching magnetic structure traced by a cluster of spicules. However, they develop a helical morphology, while the Hαspicules maintain straight, linear trajectories elsewhere. Alongside the spicules, thin, elongated red- and blueshifted Hαfeatures appear to envelope the EUV jets, which we tentatively call sheath flows. The EUI jet moving upward at a speed of ∼110 km s−1is joined by a strong Hαredshift at ∼20 km s−1to form bidirectional outflows lasting ∼2 minutes. Using AI-assisted differential emission measure analysis of SolO’s Full Sun Imager, we derived total energy of the EUV jet as ∼1.9 × 1026erg with 87% in thermal energy and 13% in kinetic energy. The parameters and morphology of this small-scale EUV jet are interpreted based on a thin flux tube model that predicts Alfvénic waves driven by impulsive interchange reconnection localized as narrowly as ∼1.6 Mm with a magnetic flux of ∼5.4 × 1017Mx, belonging to the smallest magnetic features in the quiet Sun. This detection of intricate corona–chromospheric coupling highlights the power of high-resolution imaging in unraveling the mechanisms behind small-scale solar ejections across atmospheric layers. 
    more » « less
  3. ; ; ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract Minifilaments are widespread small-scale structures in the solar atmosphere. To better understand their formation and eruption mechanisms, we investigate the entire life of a sigmoidal minifilament located below a large quiescent filament observed by Big Bear Solar Observatory/Goode Solar Telescope on 2015 August 3. The Hαstructure initially appears as a group of arched threads, then transforms into two J-shaped arcades, and finally forms a sigmoidal shape. Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly observations in 171 Å show that two coronal jets occur around the southern footpoint of the minifilament before the minifilament eruption. The minifilament eruption starts from the southern footpoint, then interacts with the overlying filament and fails. The aforementioned observational changes correspond to three episodes of flux cancellations observed by SDO/Helioseismic and Magnetic Imager. Unlike previous studies, the flux cancellation occurs between the polarity where the southern footpoint of the minifilament is rooted and an external polarity. We construct two magnetic field models before the eruption using the flux rope insertion method and find a hyperbolic flux tube above the flux cancellation site. The observation and modeling results suggest that the eruption is triggered by the external magnetic reconnection between the core field of the minifilament and the external fields due to flux cancellations. This study reveals a new triggering mechanism for minifilament eruptions and a new relationship between minifilament eruptions and coronal jets. 
    more » « less
  4. ; ; ; ; ; ; (, The Astrophysical Journal Letters)
    Abstract Recurrent chromospheric fan-shaped jets highlight the highly dynamic nature of the solar atmosphere. They have been named as “light walls” or “peacock jets” in high-resolution observations. In this study, we examined the underlying mechanisms responsible for the generation of recurrent chromospheric fan-shaped jets utilizing data from the Goode Solar Telescope at Big Bear Solar Observatory, along with data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. These jets appear as dark elongated structures in Hαwing images, persist for over an hour, and are located in the intergranular lanes between a pair of same-polarity sunspots. Our analysis reveals that magnetic flux cancellation at the jet base plays a crucial role in their formation. HMI line-of-sight magnetograms show a gradual decrease in opposite-polarity fluxes spanning the sequence of jets in Hα−0.8 Å images, suggesting that recurrent magnetic reconnection, likely driven by recurrent miniature flux-rope eruptions that are built up and triggered by flux cancellation, powers these jets. Additionally, magnetic field extrapolations reveal a 3D magnetic null-point topology at the jet formation site ∼1.25 Mm height. Furthermore, we observed strong brightening in the AIA 304 Å channel above the neutral line. Based on our observations and extrapolation results, we propose that these recurrent chromospheric fan-shaped jets align with the minifilament eruption model previously proposed for coronal jets. Though our study focuses on fan-shaped jets in between same-polarity sunspots, a similar mechanism might be responsible for light-bridge-associated fan-shaped jets. 
    more » « less
  5. ; ; ; ; (, The Astrophysical Journal)
    Abstract Minifilament eruptions producing small jets and microflares have mostly been studied based on coronal observations at extreme-ultraviolet and X-ray wavelengths. This study presents chromospheric plasma diagnostics of a quiet-Sun minifilament of size ∼ 2″ × 5″ with a sigmoidal shape and an associated microflare observed on 2021 August 7 17:00 UT using high temporal and spatial resolution spectroscopy from the Fast Imaging Solar Spectrograph (FISS) and high-resolution magnetograms from the Near InfraRed Imaging Spectropolarimeter (NIRIS) installed on the 1.6 m Goode Solar Telescope at Big Bear Solar Observatory. Using FISS Hαand Caii8542 Å line spectra at the time of the minifilament activation we determined a temperature of 8600 K and a nonthermal speed of 7.9 km s−1. During the eruption, the minifilament was no longer visible in the Caii8542 Å line, and only the Hαline spectra were used to find the temperature of the minifilament, which reached 1.2 × 104K and decreased afterward. We estimated thermal energy of 3.6 × 1024erg from the maximum temperature and kinetic energy of 2.6 × 1024erg from the rising speed (18 km s−1) of the minifilament. From the NIRIS magnetograms we found small-scale flux emergence and cancellation coincident with the minifilament eruption, and the magnetic energy change across the conjugate footpoints reaches 7.2 × 1025erg. Such spectroscopic diagnostics of the chromospheric minifilament complement earlier studies of minifilament eruptions made using coronal images. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email