Most pictures of stars in our galaxy show them as tiny jewels against a sea of darkness. This one’s a little different.
U Antliae, one of the members of the constellation Antlia, is located in the southern hemisphere of the sky. About 2,700 years ago, the star expelled a bunch of gas at high speed, creating a thin shell around itself. Thanks to powerful telescopes, astronomers can now take a close-up picture of it.
U Antliae is a carbon star, which means its atmosphere contains more carbon than oxygen. As the star has aged, carbon has given it and its surrounding bubble a red hue.
Stars in their prime produce light through nuclear reactions in their cores that turn hydrogen into helium. But when stars start to lose their hydrogen reserves, their cores can become so hot that they transform helium into carbon. That carbon is ejected to the star’s outer layers, where it produces a material that scatters blue and green light. The red light persists, and eventually travels many light-years to Earth, where telescopes detect it and astronomers turn it into the mesmerizing image at the top of this story.
The photo, released Wednesday along with research in Astronomy & Astrophysics, comes from the the Atacama Large Millimeter/submillimeter Array, or ALMA. ALMA, a radio telescope stationed in the desert of northern Chile, is one of the most powerful observatories in the world. It’s built to measure the wavelengths of light coming from some of the most distant astronomical objects, including the very first stars and galaxies in the universe.