This NASA/ESA Hubble Space Telescope image of the cluster Westerlund 2 and its surroundings has been released to celebrate Hubble’s 25th year in orbit

The Hubble Space Telescope is turning 25 tomorrow, and in celebration of this day, NASA and the ESA are focusing the telescope in on some of the most astounding features in our universe. Case in point, meet Westerlund 2 (though honestly,  it looks more like some kind of dream vision that would appear in Lewis Carrol's Wonderland). The Hubble team describes the image in less surreal terms, noting how the stars appear to sparkle in the image. They assert that "the brilliant tapestry of young stars flaring to life resemble a glittering fireworks display."

The image features a giant cluster of about 3,000 stars and a fantastic rainbow nebula. These objects wander through the cosmos some 20,000 light-years from Earth in the constellation Carina.

Artist's impression. Credit: David A. Aguilar

Ultimately, this enormous star cluster is still a baby, only about 2 million years old. However, despite its infancy, it contains some of our galaxy's most massive and energetic stars. For example, WR20a happens to be one of the most massive binary systems in the known universe. Each of these stars is more than 80 times as massive as the sun, and they are going to get even bigger. Scientists believe that, within a million years, the two stars (which orbit each other once every 3.7 days) will connect. When this happens, it is possible that the material of one will be partially consumed by the other.

Ultimately, the stars orbit so close to one another that the gravity of each star distorts the other's shape. They are known as Wolf-Rayet stars, which is a type of star that is extremely rare and short-lived.

"Wolf-Rayet stars are likely progenitors of the extremely powerful explosions known as gamma-ray bursts," said astronomer Alceste Bonanos from the Harvard-Smithsonian Center for Astrophysics.  "These stars are already 2 or 3 million years old. In another few million years, whichever one is slightly more massive will undergo core collapse and blast off its outer layers. The companion star likely will survive despite its nearness, at least until it goes supernova sometime later."

Hubble explains the image, noting that the scattering of red dots are stars that are still in their primordial womb. The red coloring comes from the dust and gas clouds that still surround the tiny stars. Ultimately, these stars are so young (just 1 or 2 million years old) that the hydrogen in their cores hasn't even ignited yet. The blue stars that can be seen throughout the photo are mostly foreground stars.


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