An international team of astronomers from Chile and Germany has captured a picture of the red supergiant star Antares in remarkable clarity. Additionally, the team created the first map of the material velocity distribution in the atmosphere of a star other than the Sun, indicating surprising turbulence in Antares' extended atmosphere.
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| This artist’s impression shows the red supergiant star Antares. Image credit: M. Kornmesser / ESO. |
Antares, commonly known as Alpha Scorpii, is a well-studied, nearby red supergiant star located 554 light-years away. It is the fifteenth brightest star in the night sky and the brightest in the Scorpius constellation. Antares is one of the biggest stars, with a diameter around 700 times that of the Sun and a mass of 12 times that of the Sun.
This is the most detailed image ever of the red supergiant star Antares or any other star apart from the Sun.
Antares is thought to have started life with a mass closer to 15 times that of the Sun and to have lost three solar masses of material over its lifetime. Dr. Keiichi Ohnaka of Chile's Universidad Católica del Norte and co-authors spotted Antares using ESO's Very Large Telescope Interferometer (VLTI) on Cerro Paranal.
“How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century,” Dr. Ohnaka said.
“VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares — a crucial step towards clarifying this problem. The next challenge is to identify what’s driving the turbulent motions.”
Astronomers generated the first two-dimensional velocity map of a star other than the Sun's atmosphere. They accomplished this by combining the VLTI with three Auxiliary Telescopes and an instrument named AMBER to create several photos of Antares' surface across a narrow range of infrared wavelengths.
They then utilised these data to compute the difference between the atmospheric gas's speed at various locations on the star and the star's average speed. This resulted in the first map of the atmospheric gas's relative velocity throughout the whole disc of Antares – the first of its kind for a star other than the Sun.
“We found turbulent, low-density gas much further from the star than predicted,” the authors said.
“The movement could not result from convection, that is, from large-scale movement of matter which transfers 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 of red supergiants like Antares.”
Reference(s): ESO, Research Paper
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