Found around 604 light-years from Earth, in the constellation Scorpius, is the red supergiant star Antares. When scientists estimated its diameter in the past, they determined that about 700 of our own suns could fit in the supergiant. It turns out, however, that Antares is much larger than that, as a new radio map created with the help of two powerful telescope arrays reveals that the red supergiant’s atmosphere goes beyond its radius.
With this detailed map, the team found that Antares' chromosphere, a gaseous layer that creates a star's outer atmosphere along with its corona, stretches to 2.5 times the star's radius. For context, our sun's chromosphere only extends to 0.5% of our star's radius.
"The size of a star can vary dramatically depending on what wavelength of light it is observed with," Eamon O'Gorman, a researcher at the Dublin Institute for Advanced Studies in Ireland and lead author of this study, said in a statement. "The longer wavelengths of the VLA revealed the supergiant's atmosphere out to nearly 12 times the star's radius."
The star is indeed worthy of being called a supergiant.
More details about this over at Space.com.
(Image Credit: NRAO/AUI/NSF, S. Dagnello/ Space.com)