VY Canis Majoris

VY Canis MajorisAstronomers have studied VY Canis Majoris, a red supergiant star that is also classified as a hypergiant because of its very high luminosity, for more than a century. The star is located 5,000 light-years away. It is 500,000 times brighter and about 30 to 40 times more massive than the Sun. If VY Canis Majoris were at the center of our Solar System, its surface could extend to the orbit of Saturn. The star is also in the process of falling apart, and astronomers have learned that its gaseous outflows are more complex than originally thought.

The star has had many outbursts as it nears the end of its life, and the eruptions have formed loops, arcs, and knots of material moving at various speeds and in many different directions. The outermost material was ejected about 1,000 years ago, while a knot near the star may have been ejected as recently as 50 years ago

The typical red supergiant phase of a dying star lasts about 500,000 years as the massive star becomes a red supergiant that has exhausted the hydrogen fuel at its core. As the core contracts under gravity, the outer layers expand, the star’s diameter grows as much as 100 times larger, and it begins to lose mass at a higher rate. VY Canis Majoris has probably already shed about half of its mass, and it will eventually explode as a supernova.

Image Credit: NASA

A Yellow Hypergiant

Yellow SupergiantHR 5171, the brightest star near the middle of this wide-field image, is a yellow hypergiant. Hypergiants are a very rare type of star; only a dozen are known in our galaxy. HR 5171 is over 1300 times the size of the Sun, making it one of the ten largest stars found to date. Observations with ESO’s Very Large Telescope Interferometer have shown that it is actually a double star, with its companion so close that it’s in contact with the main star.

Credit: ESO / Digitized Sky Survey 2