Huge Yellow Star Found With Another Star On Its SurfaceBy Steven Sparkman | March 12, 2014
The largest yellow star ever discovered, 1300 times the diameter of our sun, has another star orbiting so closely they're actually touching.
There are somewhere around 300 billion stars in our galaxy, so if the discovery of a single star is enough to make headlines, you better believe it's an impressive one.
Scientists at the European Southern Observatory, or ESO, say a yellow hypergiant in the constellation Centaurus is the largest yellow star ever discovered, and an easy contender for the top 10 largest stars of any kind. This is an actual photograph of it. (Via ESO / Digitized Sky Survey 2)
Yellow hypergiants are one of the rarest kinds of star, with only around a dozen ever discovered. That's because they're thought to be undergoing a radical change from red to blue, and the process doesn't take very long. (Via ESO / Nick Risinger / Digitized Sky Survey 2)
The star was already known to be a yellow hypergiant, but astronomers weren't sure how big it was. They used the Very Large Telescope Array in northern Chile to take a closer look. (Via ESO)
Ok, so rather than throw a bunch of numbers at you, here are a couple of the science media's best comparisons to help you understand what the researchers found.
It's 1300 times the diameter of our sun. New Scientist crunched the numbers and found, "That means it would engulf all the planets between Mercury and Jupiter if placed at the centre of our solar system."
It's 12,000 light-years away, which is pretty far, but Discover Magazine points out "It's also about a million times brighter than our sun" meaning "It's bright enough that you could still spot it with the naked eye under ideal conditions." As far as we can tell, that makes it one of the most distant individual stars you can see in the night sky.
It's also getting bigger. Even though the star is already nearly twice as big as astronomers thought yellow hypergiants could get, a look back at older data found it's actually grown over the last 40 years. And that's not the only surprise.
The huge star has a tiny twin! The pair make up a binary system, and the lead researcher says "The two stars are so close that they touch and the whole system resembles a gigantic peanut." Yes, the two stars physically touch. (Via ESO)
So there are a number of reasons why this discovery is such an oddity. Studying the unique system will hopefully give scientists more insight into how hypergiants age and evolve, as well as, you know, the effects of having a star on top of another star.