Antares’ vast blobby atmosphere
Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA), astronomers have been able to map out the gigantic atmosphere of gas that surrounds the red gas supergiant star Antares, the closest such star to our solar system.
The ALMA and VLA map of Antares is the most detailed radio map yet of any star, other than the Sun. ALMA observed Antares close to its surface (its optical photosphere) in shorter wavelengths, and the longer wavelengths observed by the VLA revealed the star’s atmosphere further out. As seen in visible light, Antares’ diameter is approximately 700 times larger than the Sun. But when ALMA and the VLA revealed its atmosphere in radio light, the supergiant turned out to be even more gigantic.
“The size of a star can vary dramatically depending on what wavelength of light it is observed with,” explained Eamon O’Gorman of the Dublin Institute for Advanced Studies in Ireland and lead author of the study published in the June 16 edition of the journal Astronomy & Astrophysics. “The longer wavelengths of the VLA revealed the supergiant’s atmosphere out to nearly 12 times the star’s radius.”
The image to the right, cropped and reduced to post here, is what these two telescopes detected. As you can see, the outer atmosphere of the star is very uneven, confirming what other observations of both Antares and Betelgeuse has seen.
These stars are giant gasbags. It appears their shape fluctuates depending on the local “weather” in each star’s atmosphere.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA), astronomers have been able to map out the gigantic atmosphere of gas that surrounds the red gas supergiant star Antares, the closest such star to our solar system.
The ALMA and VLA map of Antares is the most detailed radio map yet of any star, other than the Sun. ALMA observed Antares close to its surface (its optical photosphere) in shorter wavelengths, and the longer wavelengths observed by the VLA revealed the star’s atmosphere further out. As seen in visible light, Antares’ diameter is approximately 700 times larger than the Sun. But when ALMA and the VLA revealed its atmosphere in radio light, the supergiant turned out to be even more gigantic.
“The size of a star can vary dramatically depending on what wavelength of light it is observed with,” explained Eamon O’Gorman of the Dublin Institute for Advanced Studies in Ireland and lead author of the study published in the June 16 edition of the journal Astronomy & Astrophysics. “The longer wavelengths of the VLA revealed the supergiant’s atmosphere out to nearly 12 times the star’s radius.”
The image to the right, cropped and reduced to post here, is what these two telescopes detected. As you can see, the outer atmosphere of the star is very uneven, confirming what other observations of both Antares and Betelgeuse has seen.
These stars are giant gasbags. It appears their shape fluctuates depending on the local “weather” in each star’s atmosphere.