Stiff breeze in space: Researchers measured solar wind from three stars for the first time

2024-04-12 15:00:51

Viennese astronomers report new results in the journal “Nature Astronomy”.

A team of astronomers in Vienna has succeeded for the first time in measuring the solar winds that blow distant stars into their immediate cosmic environment using X-ray analyzes and deriving the wind speeds. The results presented in the journal “Nature Astronomy” on three celestial bodies similar to our sun reveal that a significantly different, stronger stellar wind blows there.

In their observations, the scientists led by astrophysicist Kristina Kislyakova from the University of Vienna focused on the star “70 Ophiuchi”, which is around 16.6 light years away from the Sun, the star “epsilon Eridani”, which is around 10.5 light years away, and on the star “70 Ophiuchi”, which is around 10.5 light years away once focused on “61 Cygni”, which is located around a light year further away. Charged particles – especially protons and electrons as well as mainly hydrogen and helium ions, but also heavier elements such as oxygen, carbon and iron – are constantly streaming into space from our sun. This so-called solar wind creates a bubble of plasma called a “heliosphere” around our solar system. For other stars we speak of an “astrosphere”.

The slow loss of mass of celestial bodies can be seen in the stellar wind. Observing this directly with more distant stars that are similar to the sun – so-called main sequence stars – has not yet been possible with any degree of precision, according to a release from the University of Vienna on Friday.

“For three decades, many groups around the world have been trying to detect winds around sun-like stars and measure their strength, but until now there has been only indirect evidence for the existence of such winds, based on their secondary effects on the star or its surroundings,” he said Head of the “Star and Planet Formation” research group, Manuel Güdel, who was involved in the publication. The key to making this possible lies in analyzing data on the X-rays emitted by the ions in the stellar wind. The Vienna group relied on recordings from the XMM-Newton space telescope.

The challenge was, among other things, to distinguish the X-ray emissions from the solar wind from the more prominent emissions from the individual stars themselves. The key lay in the “fingerprints” in the frequency spectrum left by the oxygen ions that move away from the central star with the solar wind. “We have developed a new algorithm that separates the star’s X-ray emissions from those of the astrosphere,” Kislyakova explained. “Our new X-ray-based results now pave the way to directly find and even image these winds and study their interactions with the surrounding planets,” said Güdel.

In the case of the star “70 Ophiuchi”, the new calculations suggest that it loses around 66 times the mass of our sun, which corresponds to a correspondingly stronger “70 Ophiuchi” wind. “epsilon Eridani” with around 16 times and “61 Cygni” with almost ten times the values ​​were significantly less emitting, but still significantly more active than our central star. The scientists explain the higher wind speeds with the stronger magnetic activity of the three stars examined.

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