When a region of the solar atmosphere suddenly brightens like a burst of fire, the flare typically lasts minutes to hours. A research team at the Chinese Academy of Sciences' National Space Science Center has discovered that inside this fire, smaller flames are rapidly "blinking" — with periods of 6 to 24 seconds and the shortest heating episodes lasting only 2 to 3 seconds. In other words, magnetic reconnection exhibits a series of extremely fast energy pulses at finer scales, with bright cores sliding at high speed along the flare ribbon. The results were published on August 31, 2026 in The Astrophysical Journal.
Solar flares: violently cutting the 'magnetic bow'
A solar flare is an explosive release of magnetic energy in the solar atmosphere. A typical flare heats a localized region to millions of degrees within minutes to hours and emits electromagnetic radiation across the full spectrum, from radio to X-rays and gamma rays.
Its physical root is magnetic reconnection — the process in which magnetic field lines are 'cut' and 'reconnected,' converting energy stored in the magnetic field into kinetic and thermal energy of plasma. This process occurs in the solar corona as well as in stellar coronae, planetary magnetospheres, accretion disks, and even laboratory plasmas.
Understanding magnetic reconnection means understanding the common mechanism behind most high-energy explosive phenomena in the universe.
Yet for decades the physical picture has been essentially two-dimensional. What does 3D magnetic reconnection look like? Observational evidence has long been scarce. Solar flares are the ideal 'natural laboratory' for studying 3D reconnection: flare ribbons are fine structures formed when high-energy particles accelerated by reconnection deposit energy in the lower atmosphere, and their dynamical evolution is a probe for diagnosing reconnection in the coronal current sheet.
'Blinking' and 'sliding': 12 years of high-time-resolution IRIS data provide answers
A team led by the National Space Science Center of the Chinese Academy of Sciences used 12 years of ultra-high time-resolution (1–2 second) observations from NASA's IRIS (Interface Region Imaging Spectrograph) satellite — resolution high enough to capture transient phenomena that previous observations completely missed.
The researchers observed two key phenomena in the bright cores (fine structures) of flare ribbons:
1. Rapid 'blinking'
The bright cores undergo quasi-periodic brightness variations with periods of roughly 6 to 24 seconds. The shortest heating duration is only about 2 to 3 seconds — meaning energy deposition is concentrated in extremely small, localized regions of the flare ribbon bright cores, with energy injection lasting only seconds.
> Why does 'blinking' matter? In the old 2D picture, energy release was viewed as a one-time dump. But the 6–24 second quasi-periodicity shows that reconnection is pulsed and repetitive, with each episode lasting only seconds. This behavior is explained by the classic theory that reconnection is driven by tearing-mode instabilities generating many small magnetic islands, whose formation and merging produce pulsed bursts.
2. Sliding along the flare ribbon
Some bright cores exhibit sliding motion along the flare ribbon, at speeds of 20 to 1,800 km/s.
Sliding should not occur in 2D reconnection. It is a characteristic observational signature of 3D magnetic reconnection — the apparent motion of field lines as they reconnect.
Putting the two phenomena together: flare ribbon bright cores simultaneously show 'sliding' and 'blinking,' revealing that magnetic reconnection has both 'magnetic-island-mediated' and 'three-dimensional' properties. This is precisely the picture theorists have lacked direct evidence for over the past three decades.
A prediction confirmed after 30 years
Before this study, the three-dimensional pulsed explosive reconnection model — which predicts that reconnection is driven by tearing-mode instabilities generating many small magnetic islands whose continuous formation and merging give reconnection a pulsed, bursty character — long lacked direct observational data showing both the 'island pulses' and the '3D sliding' at the same time.
The 12-year accumulation of IRIS's 1–2 second time-resolution data finally completed both chains of evidence:
- 'Blinking' corresponds to the rapid energy injection of island-mediated pulses;
- 'Sliding' corresponds to the apparent motion of field lines in three-dimensional space.
- Space weather forecasting: accurate reconnection models are a prerequisite for predicting flare energy release.
- Controlled nuclear fusion: tearing-mode instabilities are a main cause of confinement degradation in tokamaks.
- Magnetospheric physics: reconnection events in Earth's magnetotail and substorm triggering share the same underlying physics.
- Accretion disk physics: jets around black holes and neutron stars involve reconnection-driven energy release.
- A commercial airliner cruises at about 0.25 km/s.
- A hypersonic missile travels at about 0.6 km/s.
- The lower limit of bright-core sliding speed is 80 times a jetliner's speed; the upper limit is 7,200 times.
- Chinese Academy of Sciences, "Progress in research on 3D magnetic reconnection and solar flare fine structures," 2026-08-31, https://www.cas.cn/syky/202608/t20260831_5119330.shtml
- Paper: The Astrophysical Journal, DOI 10.3847/1538-4357/ae80ae, https://iopscience.iop.org/article/10.3847/1538-4357/ae80ae
- Lead institution: National Space Science Center, Chinese Academy of Sciences
- IRIS satellite (NASA Interface Region Imaging Spectrograph) public mission documentation
The 'data threshold' in solar physics
Solar physicists have long faced the dilemma of insufficient time resolution — flares involve multi-scale energy release from seconds to hours, but most instruments sample at tens of seconds to minutes.
IRIS was designed specifically for high-time-resolution observations of the solar chromosphere and transition region. Its 1–2 second sampling accumulated high-resolution images of millions of flare events over 12 years. This study filtered bright-core samples with 'blinking + sliding' signatures from that archive — the product of large numbers plus high time resolution plus long-duration coverage.
| Dimension | Value | |---|---| | Satellite | IRIS (NASA) | | Time resolution | 1–2 seconds | | Data archive span | 12 years | | Bright-core blinking period | 6–24 seconds | | Shortest heating duration | 2–3 seconds | | Bright-core sliding speed | 20–1,800 km/s | | Journal | The Astrophysical Journal | | Publication date | 2026-08-31 | | Lead institution | National Space Science Center, CAS |
Cross-scale methodological significance
The discovery matters beyond the Sun. Magnetic reconnection is one of the most universal energy-release mechanisms in the universe — from solar and stellar flares, geomagnetic substorms, and accretion disk jets, to laboratory plasma devices (tokamaks, magneto-inertial fusion).
Completing the 3D reconnection picture has direct implications for:
The next question, noted in the paper: can these 'blinking' and 'sliding' events explain the initial pulse structures of solar energetic particle (SEP) events, and can their energy-release time series be precisely matched to satellite observations of solar energetic particles?
A sense of scale
To appreciate sliding speeds of 20–1,800 km/s:
These 'blinking' flames race across the solar atmosphere at speeds no human technology can match.