The CLASP2 space experiment participated in by the Canarias Institute of Space Research made it possible for the first time to map the solar magnetic field from the weak photosphere to the thick and hot corona. These results provide evidence that the magnetic field heats the star’s upper atmosphere, which drives solar activity.
This Chromosphere Is an area of the solar atmosphere that stretches thousands of kilometers between relatively thin and cold Photosphere (The temperature is about several thousand degrees), and the temperature range is extremely high Corona (The temperature exceeds one million degrees).
Although the temperature of the chromosphere is a hundred times lower than that of the corona, it is denser and requires more energy to maintain itself. In addition, the energy required to heat the corona must pass through the chromosphere, making it a key area for solving many key problems in solar and stellar physics.
One of the current scientific challenges is to understand how Vigorous activity in the solar atmosphere, Sometimes disturbs the earth’s magnetosphere, causing serious consequences to our current technological world.
Layers of the Sun / Mikel Rodríguez Hidalgo
In this case, right Longitudinal magnetic field Using data obtained from suborbital space experiments CLASP2, The results provided support our star’s magnetic field to heat its upper atmosphere, thereby driving solar activity.
The research was published in the journal Scientific progress, It can help scientists map the magnetic field in the entire solar atmosphere and better understand how it directs energy to the outer gaseous layer of the sun.
“If we cannot determine the atmosphere of the sun, it is impossible to understand the atmosphere of the sun. Chromosphere magnetic fieldEspecially in the outer layer, the plasma temperature is about 10,000 degrees, and the magnetic force dominates the structure and dynamics of the plasma,” ensure co-author Javier Trujillo Good, CSIC professor of IAC, he is also a scientist in the group Polmag.
The theoretical research conducted by the group shows that through observation polarization Produced by various physical mechanisms Ultraviolet radiation It is emitted by the neutral hydrogen atoms and ionized magnesium in the solar chromosphere.
Because the earth’s atmosphere absorbs the sun’s ultraviolet rays, you must observe it at an altitude of more than 100 kilometers. With this in mind, an international consortium was led by the Marshall Space Flight Center of the National Aeronautics and Space Administration (NASA), the National Astronomical Observatory of Japan (NAOJ), the French Institute of Space Astrophysics and IAC.
The team designed a series of space experiments, which were approved by NASA as part of the rocket probe research program. Their names, Chromosphere Lyman-Alpha Spectrometer (CLASP1, Launched in 2015) and Chromatography (CLASP2, Released in 2019).
This study used CLASP2 data to analyze the strength and circular polarization of the solar system. Ultraviolet radiation The plasma in the solar atmospheric activity area is within the spectral range Ion Magnesium with Neutral Manganese.
CLASP2 and Hinode data used in the study. The background is an image taken by the Solar Dynamics Observatory (SDO) satellite. / NAOJ, NASA, IAC, IAS
The circular polarization observed by CLASP2 is caused by a physical phenomenon called a phenomenon. Zeeman effect, When the atom has a magnetic field, the radiation emitted by the atom is polarized.
“The circular polarization signal in the magnesium wire is sensitive to the magnetic field in the central and outer regions of the solar chromosphere, while the circular polarization signal in the manganese wire responds to the magnetic field in the deepest region of the color layer,” explains Sontanusso, Germany, Is one of the scientists of the POLMAG group and the international team.
At the same time as CLASP2 observed, Sunrise Space Telescope It points to the same active area of the solar disk at the same time. He said: “This makes it possible to obtain information about the magnetic field in the photosphere from the polarization observed in the spectral lines of neutral iron,” he said. Andrés Asensio Ramos, Another IAC researcher who participated in the project.
The team also worked with IRIS Space Telescope (Not applicable to measuring polarization), UV intensity Has a higher spatial resolution.
Lanzamiento del Experimento CLASP2. /U.S. Army photo, Baisha Missile Range
The authors of this international study coordinated by NAOJ and Trujillo researcher Ryohko Ishikawa achieved Draw the magnetic field for the first time In the atmosphere of the entire active area observed by CLASP2, From the ball of light to the bottom of the crown.
He said: “This mapping of the magnetic field at different heights in the solar atmosphere is of great scientific significance, because it will help decipher the magnetic coupling between different regions of the solar atmosphere.” Ernest Alsina Ballester, Is a team researcher, he has just joined IAC after getting his first postdoc in Switzerland.
The results confirmed and proved that in these regions of the solar atmosphere, Magnetic line of force They swell and flood the entire chromosphere before reaching the bottom of the canopy.
The longitudinal component diagram of the magnetic field in the different layers of the photosphere and the chromosphere. / NAOJ, IAC, NASA / MSFC, IAS
Another important result of this research is Magnetic field strength The ions in the outermost layer of the chromosphere are closely related to the radiation intensity at the center of the magnesium spectral line and the pressure of the electrons in these layers, which reveals Magnetic source for heating From the outer region of the solar atmosphere.
According to the author, CLASP1 and CLASP2 space experiments represent Milestones in astrophysicsThis is the first time that it is possible to observe relatively weak polarization signals generated by various physical mechanisms in the solar ultraviolet spectrum.
These findings greatly confirmed the theoretical predictions, Verify quantum theory These scientists study the production and transfer of polarized radiation used when studying the magnetic field of the solar chromosphere.
New experiment in 2022
The team has just received good news that NASA has selected their most recent proposal to conduct a new space experiment next year, which will allow them to map the magnetic field of a larger area of the solar disk.
Trujillo said: “Obviously, a systematic observation of the solar ultraviolet radiation intensity and polarization requires a space telescope equipped with CLASP instruments, because a few minutes of suborbital observations are not enough.”
The researchers firmly believe that with the proof of CLASP, this type of space telescope will soon become a reality, and their physical interpretation of spectral polarization observations will enable people to better understand the magnetic activity in the outer region of the space telescope. The atmosphere of the sun and other stars.
R.Ishikawa et al. “Mapping the solar magnetic field from the photosphere to the bottom of the corona.” Scientific progress, 2021.