**Executive Summary**
This report details a study by the Aryabhatta Research Institute of Observational Sciences (ARIES) and IIT Delhi, published on May 20, 2026, regarding the heating of the solar corona. Using 3D magnetohydrodynamic (MHD) simulations, researchers demonstrated how transverse waves generate hidden turbulence and spectral asymmetries. These findings provide a new diagnostic tool for understanding solar dynamics, with potential for observational validation using high-resolution facilities like the Daniel K. Inouye Solar Telescope (DKIST).
**Key Points / Main Content**
**The Solar Corona Mystery**
* The Sun’s outer atmosphere, or corona, is significantly hotter than its visible surface, a phenomenon scientists aim to explain through the study of magnetic structures.
* Transverse MHD waves (Alfvénic or kink waves) are common in the corona and cause magnetic structures to oscillate sideways as they move outward.
**Research Methodology and Simulations**
* Researchers used advanced 3D MHD simulations combined with forward modeling to study an open-field coronal region with density inhomogeneities.
* The study analyzed the Fe XIII 10749 Å spectral line to determine how plasma emission appears when affected by transverse waves.
* Waves were driven at a lower boundary and allowed to propagate upward along structured magnetic fields.
**Development of Turbulence and Spectral Asymmetry**
* As waves propagate, density variations within magnetic plumes lead to phase mixing, which generates fine-scale structures and turbulence.
* This wave-driven turbulence results in overlapping emissions from different regions moving at different velocities.
* The combined emission produces alternating blue and red wing asymmetries in spectral lines, which were previously interpreted primarily as signatures of upward flows or jets.
* Simulated asymmetries reached up to 20 percent of the line peak intensity, with secondary velocities ranging from 30 to 40 km s⁻¹.
**Impact Analysis**
**Solar Physicists and Researchers**
**Impact**
The study provides a novel method to detect "hidden" turbulence and clarifies that transverse MHD waves alone can generate systematic spectral asymmetries. This challenges previous interpretations that attributed such asymmetries solely to mass motions or jets.
**Action Required**
Researchers should incorporate these findings into their diagnostic models to better interpret wave-driven dynamics and coronal heating mechanisms.
**Astronomical Observation Facilities (e.g., DKIST)**
**Impact**
The findings highlight the necessity of high spatial and spectral resolution to observe these complex plasma motions. The study confirms that current advanced facilities are now capable of detecting these phenomena.
**Action Required**
Facilities should utilize high-resolution instruments to seek observational evidence of the simulated red-blue spectral patterns to validate the study’s findings.
Key Entities Referenced
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital: An autonomous institute under the Department of Science and Technology that led the study into the solar corona's high temperature.
Indian Institute of Technology (IIT) Delhi: The collaborative research institution whose Department of Physics performed 3D simulations to investigate coronal spectral asymmetries.
Department of Science and Technology (DST): The central government department that oversees ARIES and supports the research initiative.
The Astrophysical Journal: The scientific journal where the study's findings regarding wave-driven turbulence and solar plasma dynamics were published.
Daniel K. Inouye Solar Telescope (DKIST): A high-resolution observational facility mentioned as essential for future detection of the predicted solar wave phenomena.
Ministry of Science & Technology
NEW STUDY PAVES WAY FOR SOLVING THE
MYSTERIOUSLY HIGH TEMPERATURE OF
SOLAR CORONA
Posted On: 20 MAY 2026 4:16PM by PIB Delhi
A novel way to detect hidden turbulence in the Sun’s outer atmosphere or corona could help scientists gain
new insights into the long-standing mystery of why the corona is much hotter than the Sun’s visible
surface.
The Sun’s outer atmosphere, the corona, is filled with magnetic structures that constantly sway as waves
travel along them. Among the most common of these are propagating transverse magnetohydrodynamic
(MHD) waves, often described as Alfvénic or kink waves. These waves make coronal structures oscillate
sideways as they move outward along these magnetic structures.
Spectroscopically, such waves are known to produce alternating red and blue Doppler shifts, signatures of
plasma moving toward and away from the observer due to transverse motions perpendicular to the
magnetic field. However, whether these propagating transverse waves can also modify the shape of
coronal spectral lines, producing measurable asymmetries in otherwise Gaussian profiles, has not yet been
clearly established observationally.
Previous observations of the corona and transition region have revealed ubiquitous blueward asymmetries
in spectral lines. These have largely been interpreted as signatures of upward flows, jets, or mass motions
along magnetic field lines. In contrast, transverse waves are often considered nearly incompressible and
therefore not expected to produce strong line profile asymmetries. As a result, their potential contribution
to spectral asymmetries has received far less attention.
In a recent study by Aryabhatta Research Institute of Observational Sciences, (ARIES) Nainital, an
autonomous institute of the Department of Science and Technology (DST), and Indian Institute of
Technology (IIT) Delhi, advanced three-dimensional MHD simulations combined with forward modeling
were used to investigate this question. The researchers Ms. Ambika Saxena, PhD student at ARIES and
Prof. Vaibhav Pant from the Department of Physics, IIT, Delhi, performed simulations of an open-field
coronal region containing density inhomogeneities across its transverse cross-section. Transverse waves
were driven at the lower boundary and allowed to propagate upward along the structured magnetic field.
Using forward modeling, they then computed how the plasma emission would appear in a commonly
observed coronal spectral line, Fe XIII 10749 Å.Figure 1: Starting point of the simulation. This image shows how the plasma is arranged at the
beginning. The upward direction corresponds to height in the solar atmosphere, while the patchy
pattern shows variations in density across the structure.
The simulations in the study published in The Astrophysical Journal, revealed a consistent pattern. As
transverse waves propagate along a structured magnetic plume, the plasma within the structure does not
move uniformly. The cross-section of the plume contains density variations, and as the wave evolves, it
generates increasingly fine-scale structure through phase mixing. This process leads to the development of
turbulence, producing small-scale velocity and density structuring within the magnetic structure.
Because the solar corona is optically thin, emission from many parts of the structure overlaps along the
line of sight. Different regions move with different velocities at the same time. When this emission is
combined, the resulting spectral line is no longer perfectly symmetric. Instead, it develops alternating blue
and red wing asymmetries that switch in time and height as the wave travels.
Figure 2: Evolution of spectral asymmetry with radial height. Panels (1) and (2) show
snapshots at two different heights in the simulated corona. The maps illustrate how plasma
moving at different speeds contributes to the observed signal. These patterns reflect the complex
motions generated by the propagating wave.
Importantly, these asymmetries arise naturally from the combined effects of transverse wave dynamics,
cross-sectional inhomogeneities, and the development of wave-driven turbulence. The simulated
asymmetries can reach up to about 20 percent of the line peak intensity, with apparent secondary velocitiesof 30 to 40 km s⁻¹. Moreover, the alternating red–blue pattern itself propagates outward at speeds
consistent with the wave.
These results demonstrate that propagating transverse MHD waves alone can generate systematic
alternating spectral asymmetries. With the high spatial and spectral resolution now available from
facilities such as DKIST, observations of this phenomenon may soon become possible, offering a new
diagnostic of wave-driven dynamics in the solar corona.
Publication link: https://iopscience.iop.org/article/10.3847/1538-4357/ae2482
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