An international team ofastronomers from Chile and Germany has managed to capture an image ofunprecedented detail of another star — that isn’t the Sun — the red supergiantstar Antares.
The team has also made the first map of the velocities ofmaterial in the atmosphere of a star other than the Sun, revealing unexpectedturbulence in the extended atmosphere of Antares.
Image description: This artist’s impression shows the red supergiant star Antares. Image credit: M. Kornmesser / ESO.
Antares, also designatedAlpha Scorpii, is a well-studied, close red supergiant star at a distance of554 light years. It is the fifteenth-brightest star in the night sky and thebrightest star in the constellation of Scorpius. With a diameter about 700times that of the Sun and a mᴀss about 12 times solar, Antares is one oflargest stars.
This is the most detailed image ever of the red supergiant star Antares, or any other star apart from the Sun. Image credit: K. Ohnaka / ESO.
It is thought that Antaresstarted life with a mᴀss more like 15 times that of the Sun, and has shed threesolar-mᴀsses of material during its life. To directly see the gas motions inits atmosphere, Dr. Keiichi Ohnaka of the Universidad Católica del Norte inChile and co-authors observed Antares with ESO’s Very Large TelescopeInterferometer (VLTI) located on Cerro Paranal in Chile.
“How stars like Antares losemᴀss so quickly in the final phase of their evolution has been a problem forover half a century,” Dr. Ohnaka said.“VLTI is the only facilitythat can directly measure the gas motions in the extended atmosphere of Antares— a crucial step towards clarifying this problem. The next challenge is toidentify what’s driving the turbulent motions.”
The astronomers created thefirst two-dimensional velocity map of the atmosphere of a star other than theSun. They did this using the VLTI with three of the Auxiliary Telescopes and aninstrument called AMBER to make separate images of the surface of Antares overa small range of infrared wavelengths.
They then used these data tocalculate the difference between the speed of the atmospheric gas at differentpositions on the star and the average speed over the entire star. This resultedin a map of the relative speed of the atmospheric gas across the entire disc ofAntares — the first ever created for a star other than the Sun.
“We found turbulent, low-density gas muchfurther from the star than predicted,” the authors said.“The movement could notresult from convection, that is, from large-scale movement of matter whichtransfers energy from the core to the outer atmosphere of many stars.”“A new, currently unknown,process may be needed to explain these movements in the extended atmospheres ofred supergiants like Antares.”
The research is published in the journal Nature.
Via sci-news
