The collaboration between a solar observation satellite and a sounding rocket telescope allowed scientists to determine Sun's magnetic field strength. Experts, through a triad of NASA missions, published their study in Science Advances.
The chromosphere lies between the photosphere, or bright surface of the Sun that emits visible light, and the super-heated corona, or outer atmosphere of the Sun at the source of solar eruptions. The chromosphere is a key link between these two regions and a missing variable determining the Sun’s magnetic structure.
The Sun still holds many mysteries for astronomers, despite being the brightest star in the sky. It is widely agreed that in heating the solar corona, magnetic fields play an essential role. But the specifics of this mechanism are still uncertain. It is crucial to know the chromosphere's magnetic field, which is found on the visible layer of the Sun, to solve the riddle.
NASA Marshall Space Flight Center, the National Astronomical Observatory of Japan, the French Institute of Space Astrophysics and the Spanish Instituto de Astrofísica de Canarias analyzed the data collected over six and a half minutes from the CLASP2 probe rocket experiment.
Above the active region layer and its surroundings, they determined the longitudinal portion of the magnetic field. The scientists studied the magnetic field's signature on the chromosphere's ultraviolet light to do this.
In the lower, middle, and upper regions of the chromosphere, the high-quality CLASP2 data allowed scientists to explore the magnetic field power. Simultaneously, data collected from the Japanese satellite for Sun Hinode observation released details on the photosphere's own magnetic field. Scientists find that the layer's magnetic field is highly organized in the photosphere but extends, mixes, and spreads downwards easily in the chromosphere. The research findings put scientists better at solving how energy is transmitted to the corona from the lower layers of the Sun by magnetic fields.
Magnetic Fields Analysis
NASA said institutions from France, Japan, Spain, and the United States made a new strategy to measure Sun's chromosphere's magnetic field despite its untidiness.
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They installed their solar observatory on a sounding rocket to adjust an instrument that flew in 2015, so named for the nautical term to measure sound significance.
For short, few-minute observation, sounding rockets launch into space before dropping back to Earth. They are also a perfect stage to carry out new concepts and revolutionary methods, more inexpensive and easier to develop and fly than larger satellite missions.
The team took advantage of the Zeeman effect, a century-old technique, to measure magnetic field power.
Astronomer George Ellery Hale's first application of the Zeeman effect to the Sun, in 1908, is how we discovered that the Sun was magnetic. The Zeeman effect, per Interesting Engineering, refers to the fact that spectral lines break into multiples in the presence of strong magnetic fields. The further apart they split, the stronger the field of magnetism.
Nevertheless, the turbulent chromosphere appears to "smear" spectral lines. Hence, scientists found it impossible to tell how far apart they split, which is why previous missions had difficulty calculating it. The breakthrough of CLASP2 was to work around this limitation by calculating "circular polarization," a slight change in the direction of light that occurs as part of the Zeeman effect.
The CLASP2 team was able to calculate, by carefully calculating the degree of circular polarization, how far apart those smeared lines must have broken, and how strong the magnetic field was.
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