NASA sounding rocket finds helium structures in sun's atmosphere

August 07, 2020

Helium is the second most abundant element in the universe after hydrogen. But scientists aren't sure just how much there actually is in the Sun's atmosphere, where it is hard to measure. Knowing the amount of helium in the solar atmosphere is important to understanding the origin and acceleration of the solar wind - the constant stream of charged particles from the Sun.

In 2009, NASA launched a sounding rocket investigation to measure helium in the extended solar atmosphere - the first time we've gathered a full global map. The results, recently published in Nature Astronomy, are helping us better understand our space environment.

Previously, when measuring ratios of helium to hydrogen in the solar wind as it reaches Earth, observations have found much lower ratios than expected. Scientists suspected the missing helium might have been left behind in the Sun's outermost atmospheric layer - the corona - or perhaps in a deeper layer. Discovering how this happens is key to understanding how the solar wind is accelerated.

To measure the amount of atmospheric helium and hydrogen, NASA's Helium Resonance Scattering in the Corona and Heliosphere, or HERSCHEL, sounding rocket took images of the solar corona. Led by the Naval Research Lab in Washington, D.C., HERSCHEL was an international collaboration with the Osservatorio Astrofisico di Torino in Italy and the Institute d'Astrophysique Spatiale in France.

HERSCHEL's observations showed that helium wasn't evenly distributed around the corona. The equatorial region had almost no helium while the areas at mid latitudes had the most. Comparing with images from ESA/NASA's Solar and Heliospheric Observatory (SOHO), the scientists were able to show the abundance at the mid latitudes overlaps with where Sun's magnetic field lines open out into the solar system.

This shows that the ratio of helium to hydrogen is strongly connected with the magnetic field and the speed of the solar wind in the corona. The equatorial regions, which had low helium abundance measurements, matched measurements from the solar wind near Earth. This points to the solar atmosphere being more dynamic than scientists thought.

The HERSCHEL sounding rocket investigation adds to a body of work seeking to understand the origin of the slow component of the solar wind. HERSCHEL remotely investigates the elemental composition of the region where the solar wind is accelerated, which can be analyzed in tandem with in situ measurements of the inner solar system, such as those of the Parker Solar Probe. While the heat of the Sun is enough to power the lightest element - ionized hydrogen protons - to escape the Sun as a supersonic wind, other physics must help power the acceleration of heavier elements such as helium. Thus, understanding elemental abundance in the Sun's atmosphere, provides additional information as we attempt to learn the full story of how the solar wind is accelerated.

In the future, scientists plan to take more observations to explain the difference in abundances. Two new instruments - Metis and EUI on board ESA/NASA's Solar Orbiter - are able to make similar global abundance measurements and will to help provide new information about the helium ratio in the corona.
-end-


NASA/Goddard Space Flight Center

Related Magnetic Field Articles from Brightsurf:

Investigating optical activity under an external magnetic field
A new study published in EPJ B by Chengping Yin, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China, aims to derive an analytical model of optical activity in black phosphorous under an external magnetic field.

Magnetic field and hydrogels could be used to grow new cartilage
Instead of using synthetic materials, Penn Medicine study shows magnets could be used to arrange cells to grow new tissues

Magnetic field with the edge!
This study overturns a dominant six-decade old notion that the giant magnetic field in a high intensity laser produced plasma evolves from the nanometre scale.

Global magnetic field of the solar corona measured for the first time
An international team led by Professor Tian Hui from Peking University has recently measured the global magnetic field of the solar corona for the first time.

Magnetic field of a spiral galaxy
A new image from the VLA dramatically reveals the extended magnetic field of a spiral galaxy seen edge-on from Earth.

How does Earth sustain its magnetic field?
Life as we know it could not exist without Earth's magnetic field and its ability to deflect dangerous ionizing particles.

Scholes finds novel magnetic field effect in diamagnetic molecules
The Princeton University Department of Chemistry publishes research this week proving that an applied magnetic field will interact with the electronic structure of weakly magnetic, or diamagnetic, molecules to induce a magnetic-field effect that, to their knowledge, has never before been documented.

Origins of Earth's magnetic field remain a mystery
The existence of a magnetic field beyond 3.5 billion years ago is still up for debate.

New research provides evidence of strong early magnetic field around Earth
New research from the University of Rochester provides evidence that the magnetic field that first formed around Earth was even stronger than scientists previously believed.

Massive photons in an artificial magnetic field
An international research collaboration from Poland, the UK and Russia has created a two-dimensional system -- a thin optical cavity filled with liquid crystal -- in which they trapped photons.

Read More: Magnetic Field News and Magnetic Field Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.