NASA’s Unprecedented Map of Sun’s Magnetic Field – Including the Mysterious Chromosphere

Chromosphere 1999 Total Solar Eclipse

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The chromosphere, photographed throughout the 1999 overall solar eclipse. The red and pink colors – light given off by hydrogen – made it the name chromosphere, from the Greek “chrôma” significance color. Credit: Luc Viatour

For years after its discovery, observers might just see the solar chromosphere for a couple of short lived minutes: throughout an overall solar eclipse, when a brilliant red radiance ringed the Moon’s shape.

More than a a century later on, the chromosphere stays the most mystical of the Sun’s climatic layers. Sandwiched in between the intense surface area and the heavenly solar corona, the Sun’s external environment, the chromosphere is a location of fast modification, where temperature level increases and electromagnetic fields start to control the Sun’s habits.

Now, for the very first time, a triad of NASA objectives have actually peered into the chromosphere to return multi-height measurements of its electromagnetic field. The observations – recorded by 2 satellites and the Chromospheric Layer Spectropolarimeter 2, or CLASP2 objective, aboard a little suborbital rocket – aid expose how electromagnetic fields on the Sun’s surface area generate the fantastic eruptions in its external environment. The paper was released on February 19, 2021, in Science Advances.

A significant objective of heliophysics – the science of the Sun’s impact on area, consisting of planetary environments – is to anticipate area weather condition, which frequently starts on the Sun however can quickly spread out through area to trigger interruptions near Earth.

Driving these solar eruptions is the Sun’s electromagnetic field, the undetectable lines of force extending from the solar surface area to area well previous Earth. This electromagnetic field is challenging to see – it can just be observed indirectly, by light from the plasma, or super-heated gas, that traces out its lines like vehicle headlights taking a trip a far-off highway. Yet how those magnetic lines organize themselves – whether slack and straight or tight and twisted – makes all the distinction in between a peaceful Sun and a solar eruption.

“The Sun is both beautiful and mysterious, with constant activity triggered by its magnetic fields,” stated Ryohko Ishikawa, solar physicist at the National Astronomical Observatory of Japan in Tokyo and lead author of the paper.

Sun Regions

The chromosphere lies in between the photosphere, or intense surface area of the Sun that discharges noticeable light, and the super-heated corona, or external environment of the Sun at the source of solar eruptions. The chromosphere is an essential link in between these 2 areas and a missing out on variable identifying the Sun’s magnetic structure. Credit: Credits: NASA’s Goddard Space Flight Center

Ideally, scientists might read out the electromagnetic field lines in the corona, where solar eruptions happen, however the plasma is method too sporadic for precise readings. (The corona is far less than a billionth as thick as air at sea level.)

Instead, researchers determine the more largely jam-packed photosphere – the Sun’s noticeable surface area – 2 layers listed below. They then utilize mathematical designs to propagate that field upwards into the corona.  This technique avoids determining the chromosphere, which lies in between the 2, rather, wanting to mimic its habits.

Unfortunately the chromosphere has actually ended up being a wildcard, where electromagnetic field lines reorganize in manner ins which are tough to expect. The designs have a hard time to record this intricacy.

“The chromosphere is a hot, hot mess,” stated Laurel Rachmeler, previous NASA job researcher for CLASP2, now at the National Oceanic and Atmospheric Administration, or NOAA. “We make simplifying assumptions of the physics in the photosphere, and separate assumptions in the corona. But in the chromosphere, most of those assumptions break down.”

Institutions in the U.S., Japan, Spain and France interacted to establish an unique technique to determine the chromosphere’s electromagnetic field in spite of its messiness. Modifying an instrument that flew in 2015, they installed their solar observatory on a sounding rocket, so called for the nautical term “to sound” significance to determine. Sounding rockets introduce into area for short, few-minute observations prior to falling back to Earth. More cost effective and quicker to develop and fly than bigger satellite objectives, they’re likewise a perfect phase to evaluate out originalities and ingenious methods.

Launching from the White Sands Missile Range in New Mexico, the rocket shot to an elevation of 170 miles (274 kilometers) for a view of the Sun from above Earth’s environment, which otherwise obstructs particular wavelengths of light. They set their sights on a plage, the edge of an “active region” on the Sun where the magnetic field strength was strong, perfect for their sensing units.

As CLASP2 peered at the Sun, NASA’s Interface Region Imaging Spectrograph or IRIS and the JAXA/NASA Hinode satellite, both viewing the Sun from Earth orbit, changed their telescopes to take a look at the very same place. In coordination, the 3 objectives concentrated on the very same part of the Sun, however peered to various depths.


To procedure magnetic field strength, the group benefited from the Zeeman result, a century-old strategy. (The very first application of the Zeeman result to the Sun, by astronomer George Ellery Hale in 1908, is how we discovered that the Sun was magnetic.) The Zeeman result describes the truth that spectral lines, in the existence of strong electromagnetic fields, splinter into multiples. The further apart they divided, the more powerful the electromagnetic field.

Zeeman Effect.

The Zeeman result. This animated image reveals a spectrum with numerous absorption lines – spectral lines produced when atoms at particular temperature levels soak up a particular wavelength of light. When an electromagnetic field is presented (revealed here as blue electromagnetic field lines originating from a bar magnetic), absorption lines divided into 2 or more. The variety of divides and the range in between them exposes the strength of the electromagnetic field. Note that not all spectral lines divided in this method, which the CLASP2 experiment determined spectral lines in the ultraviolet variety, whereas this demonstration reveals lines in the noticeable variety. Credit: NASA’s Goddard Space Flight Center/Scott Weissinger

The disorderly chromosphere, nevertheless, tends to “smear” spectral lines, making it challenging to inform simply how far apart they divide – that’s why previous objectives had problem determining it. CLASP2’s novelty remained in working around this restriction by determining “circular polarization,” a subtle shift in the light’s orientation that occurs as part of the Zeeman result. By thoroughly determining the degree of circular polarization, the CLASP2 group might determine how far apart those smeared lines need to have divided, and therefore how strong the electromagnetic field was.

Hinode concentrated on the photosphere, searching for spectral lines from neutral iron formed there. CLASP2 targeted 3 various heights within the chromosphere, locking onto spectral lines from ionized magnesium and manganese. Meanwhile, IRIS determined the magnesium lines in greater resolution, to adjust the CLASP2 information. Together, the objectives kept an eye on 4 various layers within and surrounding the chromosphere.

Eventually the outcomes remained in: The very first multi-height map of the chromosphere’s electromagnetic field.

“When Ryohko first showed me these results, I just couldn’t stay in my seat,” stated David McKenzie, CLASP2 principal private investigator at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “I know it sounds esoteric – but you’ve just showed the magnetic field at four heights at the same time. Nobody does that!”

The most striking element of the information was simply how differed the chromosphere ended up being. Both along the part of the Sun they studied and at various heights within it, the electromagnetic field differed substantially.

“At the Sun’s surface we see magnetic fields changing over short distances; higher up those variations are much more smeared out. In some places, the magnetic field didn’t reach all the way up to the highest point we measured whereas in other places, it was still at full strength.”

The group wants to utilize this strategy for multi-height magnetic measurements to map the whole chromosphere’s electromagnetic field. Not just would this aid with our capability to anticipate area weather condition, it will informs us essential details about the environment around our star.

“I’m a coronal physicist – I’m really interested in the magnetic fields up there,” Rachmeler stated. “Being able to raise our measurement boundary to the top of the chromosphere would help us understand so much more, help us predict so much more – it would be a huge step forward in solar physics.”

They’ll have an opportunity to take that advance quickly: A re-flight of the objective was simply greenlit by NASA. Though the launch date isn’t yet set, the group prepares to utilize the very same instrument however with a brand-new strategy to determine a much wider swath of the Sun.

“Instead of just measuring the magnetic fields along the very narrow strip, we want to scan it across the target and make a two-dimensional map,” McKenzie stated.

Read Unprecedented Map of the Sun’s Magnetic Field Created by CLASP2 Space Experiment for more on this research study.

Reference: “Mapping Solar Magnetic Fields from the Photosphere to the Base of the Corona” by Ryohko Ishikawa, Javier Trujillo Bueno, Tanausú del Pino Alemán, Takenori J. Okamoto, David E. McKenzie, Frédéric Auchère, Ryouhei Kano, Donguk Song, Masaki Yoshida, Laurel A. Rachmeler, Ken Kobayashi, Hirohisa Hara, Masahito Kubo, Noriyuki Narukage, Taro Sakao, Toshifumi Shimizu, Yoshinori Suematsu, Christian Bethge, Bart De Pontieu, Alberto Sainz Dalda, Genevieve D. Vigil, Amy Winebarger, Ernest Alsina Ballester, Luca Belluzzi, Jiri Stepan, Andrés Asensio Ramos, Mats Carlsson and Jorrit Leenaarts, 19 February 2021, Science Advances.
DOI: 10.1126/sciadv.abe8406

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