Japan supercomputer: Fugaku succeeded in reproducing: The special rotation of the sun,
-Expectations for elucidation of fluctuations in the number of black dots-
2021/9/14
Chiba University:
Research teams such as Chiba University have succeeded for the first time in the world.
Not possible with conventional supercomputers:
With conventional supercomputer simulations, it was impossible to reproduce the special rotation of the sun.
Reproduced with the latest supercomputer Fugaku:
We succeeded in reproducing the special rotation of the sun with the world’s highest performance supercomputer “Fugaku”.
The biggest mystery in heliophysics:
The elucidation of the special rotation period of the sun is considered to be the greatest mystery in heliophysics.
It is said that it will lead to the elucidation of the phenomenon that the number of black spots of the sun fluctuates in a cycle of about 11 years.
The rotation period of the sun is special:
Unlike the Earth, which rotates at the same speed at all latitudes, the rotation period of the Sun is special.
It takes about 30 days near the North Pole and the South Pole,
It is about 25 days near the equator
It has been known for a long time by observation.
It seems that it is caused by “the function of the heat convection layer that occupies about 30% of the outside of the radius”.
I don’t know the details.
Research team simulation:
Divide the entire heat convection layer into 5.4 billion points,
Density, temperature, pressure, etc. for each
Simulate by applying precisely.
Simulation results:
As a result, we were able to reproduce the rotation of the sun, which is almost the same as the observed data.
In past supercomputers, the heat convection layer could only be divided into about 200 million points.
This time, the observation points were dramatically made finer, and the generated magnetic field was accurately reproduced.
Relationship between sun rotation and sunspot formation:
The rotation of the sun is said to be closely related to the formation of sunspots.
Sunspots increase and decrease every 11 years.
When there are many, the solar flare explosion
Emits strong electromagnetic waves,
Impair artificial satellites and power lines,
Hideyuki Hotta, Associate Professor, Chiba University:
I would like to deepen my understanding of the rotation of the sun through simulations.
This will lead to the elucidation of the mystery of the periodic increase and decrease of sunspots.
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Solar differential rotation reproduced with high-resolution simulation
H. Hotta Department of Physics, Graduate School of Science, Chiba University, Chiba, Japan
The Sun rotates differentially with a fast equator and slow pole1.
Convection in the solar interior is thought to maintain the differential rotation.
However, although many numerical simulations
have been conducted to reproduce the solar differential rotation2,3,4,5,6,7, previous high-resolution calculations with solar parameters fall into the antisolar (fast-pole) differential rotation regime.
Consequently,
we still do not know the true reason why the Sun has a fast-rotating equator.While
the construction of the fast equator requires a strong rotational influence on the convection,the previous calculations
have not been able to achieve the situation without any manipulations.The problem is called the convective conundrum8.
The convection and the differential rotation in numerical simulations were different from the observations.
Here, we show that
a high-resolution calculation succeeds in reproducing the solar-like differential rotation.Our calculations indicate that
the strong magnetic field generated by a small-scale dynamo has a significant impact on thermal convection.The successful reproduction of the differential rotation, convection and magnetic field
achieved in our calculation is an essential step to understanding the cause of the most basic nature of solar activity, specifically, the 11 yr cycle of sunspot activity.
Nature Astronomy