News – UK – NASA Missions Unprecedented Map Of Solar Magnetic Motif – Are You Betting On It?


For decades after its discovery, observers could only see the solar chromosphere for a few fleeting moments: during a total solar eclipse, when a bright red glow framed the silhouette of the moon

The chromosphere, photographed during the total solar eclipse in 1999. The red and pink hues – light emitted by hydrogen – earned it the name chromosphere, from the Greek “Chrôma”, which means color. Credits: Luc Viatour

More than a hundred years later, the chromosphere remains the most mysterious of the sun’s atmospheric layers. The chromosphere is located between the bright surface and the ethereal solar corona, the sun’s outer atmosphere It is a place of rapid change, where the temperature rises and magnetic fields dominate the behavior of the sun

Now, for the first time, a triad of NASA missions has looked into the chromosphere to return measurements of their magnetic field at multiple heights.The observations made by two satellites and the Chromospheric Layer Spectropolarimeter 2 or the CLASP2 mission on board a small suborbital Rocket were recorded showing how magnetic fields on the sun’s surface lead to brilliant eruptions in the external atmosphere The paper was published today in Science Advances

A primary goal of heliophysics – the science of the sun’s influence on space, including the planet’s atmosphere – is to predict space weather, which often starts on the sun but can spread rapidly in space, causing disturbances near the earth

These solar flares are powered by the sun’s magnetic field The invisible lines of force extend from the sun’s surface into space far behind the earth.This magnetic field is difficult to see – it can only be observed indirectly through light from the plasma or overheated gas that traces its lines like car headlights on a distant highway Arranging these magnetic lines – whether loose and straight or tight and tangled – is what makes the difference between a calm sun and a sunburst from

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

Ideally, researchers could read the magnetic field lines in the corona where solar flares occur, but the plasma is far too sparse for accurate readings (the corona is far less than a billionth as dense as air at sea level)

Instead, scientists measure the more densely packed photosphere – the sun’s visible surface – two layers below that.They then use mathematical models to propagate that field up into the corona.This approach instead skips measuring the chromosphere that lies between the two , hoping to simulate their behavior

The chromosphere lies between the photosphere, or the bright surface of the sun that emits visible light, and the sun’s overheated corona, or outer atmosphere, at the source of solar flares.The chromosphere is an important link between these two regions and a missing variable , which determines the magnetic structure of the sunCredits: Credits: NASA’s Goddard Space Flight Center

Unfortunately, the chromosphere turned out to be a placeholder in which the magnetic field lines rearrange themselves in ways that are difficult to predict. The models try to capture this complexity

“The chromosphere is a hot, hot mess,” said Laurel Rachmeler, former NASA project scientist for CLASP2, now with the National Oceanic and Atmospheric Administration (NOAA) “We’re making simplistic assumptions about physics in the photosphere and separate assumptions in the corona In the chromosphere, however, most of these assumptions collapse ”

Institutions in the US., Japan, Spain and France have jointly developed a novel approach to measure the magnetic field of the chromosphere despite its disorder. They modified an instrument that flew in 2015 and mounted their solar observatory on a rocket, which, according to the nautical term “to sound” was named, which means “to measure”. Sound rockets launch brief observations lasting a few minutes into space before falling back to earth. They are cheaper and faster to build and fly than larger satellite missions They are also an ideal stage to test new ideas and innovative techniques

The missile launched from the White Sands Missile Range in New Mexico and darted to an altitude of 172 miles to get a glimpse of the sun over the earth’s atmosphere, which is otherwise blocking certain wavelengths of light.They have a plague in their sights, the edge of an “active region” on the sun where the magnetic field strength was strong, ideal for your sensors

When CLASP2 looked at the sun, NASA’s Interface Region Imaging Spectrograph (IRIS) and the Hinode satellite JAXA / NASA, both of which were observing the sun from orbit, adjusted their telescopes to look at the same location In coordination, the three missions focused on the same part of the sun, but looked at different depths

Hinode concentrated on the photosphere and looked for spectral lines from neutral iron formed there. CLASP2 aimed at three different heights within the chromosphere and fixed spectral lines from ionized magnesium and manganese.In the meantime, IRIS has measured the magnesium lines in higher resolution, around the Calibrate CLASP2 data Together, the missions monitored four different layers within and around the chromosphere

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

The most striking aspect of the data was how different the chromosphere was. Both along the part of the Sun they studied and at different altitudes, the magnetic field varied significantly

“On the surface of the sun we see magnetic fields that change over short distances further up these variations are much more smeared. In some places the magnetic field did not reach the highest point we measured, while in other places it was still at full strength ”

The team hopes to use this technique for magnetic measurements at multiple altitudes to map the magnetic field of the entire chromosphere.This would not only help predict space weather but also provide vital information about the atmosphere around our star

“I’m a coronal physicist – I’m really interested in the magnetic fields up there,” said Rachmeler. “Being able to raise our measurement limit to the top of the chromosphere would help us understand so much more, like that much more to predict – it would be a great advance in solar physics ”

To measure the magnetic field strength, the team used the Zeeman effect, a centuries-old technique (The first application of the Zeeman effect to the sun by the astronomer George Ellery Hale in 1908 is how we learned that the sun is magnetic is) The Zeeman effect refers to the fact that in the presence of strong magnetic fields, spectral lines split into multiples, the further they split, the stronger the magnetic field

The Zeeman Effect This animated image shows a spectrum with multiple absorption lines – spectral lines that are created when atoms at certain temperatures absorb a certain wavelength of light when a magnetic field is applied (shown here as blue magnetic field lines created by a bar magnet go out), the absorption lines divide into two or more The number of divisions and the distance between them shows the strength of the magnetic field Note that not all spectral lines are divided in this way and that the CLASP2 experiment measured spectral lines in the ultraviolet range, while this demo shows lines in the visible area Credit: NASA’s Goddard Space Flight Center / Scott Weissinger

The chaotic chromosphere, however, has a tendency to “smear” spectral lines, making it difficult to tell how far apart they are – therefore previous missions had problems measuring them. The novelty of CLASP2 was to circumvent this limitation by measuring “circular polarization,” a subtle shift in light alignment that occurs as part of the Zeeman Effect. By carefully measuring the degree of circular polarization, the CLASP2 team was able to see how far apart those smeared lines must be and how strong the magnetic field was

You will soon have the chance to take this step forward: a return flight of the mission was only lit green by NASA. Although the start date has not yet been set, the team plans to use the same instrument, but with a new technique to measure a much wider strip of sun

“Instead of just measuring the magnetic fields along the very narrow strip, we want to scan it over the target and create a two-dimensional map,” McKenzie said

Magnetic Field, Chromosphere, NASA, Star, Sun, Space, Observation

News – UK – NASA Missions Create Unprecedented Map Of Solar Magnetic Motif – Are You Betting On That?
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