The Hubble telescope is world-famous for its beautiful images of our universe. Here at the Science Dunk we even posted a Hubble Hump-Day article to get us over the mid-week blues.
This week, Hubble has turned its camera to a super-star cluster called Westerlund 1. This fantastical sounding mass is just 15,000 light years away, and is home to one of the biggest stars ever discovered. The star in question has been creatively named Westerlund 1-26, and boasts an estimated radius of 1,064,574,000 kilometres (that’s over 1,530 times bigger than our own sun). If we were to replace our sun with Westerlund 1-26, the star would extend out beyond the orbit of Jupiter.
Westerlund 1-26 sits within the constellation of Ara (meaning The Altar), which, though amongst the smaller constellations, can be seen on clear nights in the Southern hemisphere. The star itself, however, is obscured by interstellar dust, so cannot be seen with the naked eye. In 2013 it was discovered that the star is surrounded by a glowing cloud of ionised hydrogen, the first of it’s kind.
Westerlund 1-26 is known as a red supergiant, and, as is the case with most large stars, has a fairly cool surface temperature of just 3000 Kelvin. This temperature means that the star emits most of its energy in infrared radiation. Westerlund 1-26 was first discovered in 1961 by Bengt Westerlund during an infrared survey in the ‘Zone of Avoidance’ (I vote to stay behind on any trips to that delightful place!) but it wasn’t until 1987 that it was officially numbered (26) and named.
Most of the stars within Westerlund 1 are thought to have formed around the same time, meaning they are all extremely similar to one another. The cluster is just three million years old (compare that to our 6.4 billion year old sun), but contains a number of rare, evolved, high-mass stars (one of which is Westerlund 1-26. As this cluster is so nearby and contains so many rarities, it is sure to become a highly-researched region within our visible skies.
Take a look at Hubble’s photo below: