The cluster of young stars hidden deep inside the cloud is about one billion times more luminous than our Sun

Mar 19, 2015 10:23 GMT  ·  By

Just one cosmic cloud in a dwarf galaxy not far from our Milky Way holds well over a million stars so young that they are not yet fully formed, University of California, Los Angeles scientists say.

Although they have not gone through all of the formation processes each and every star must complete to be worthy of being called, well, a star, these over one million fiery celestial bodies are insanely bright.

In fact, the University of California, Los Angeles astronomers who studied them estimate that the luminosity of the cluster they form exceeds that of our Sun a billion times over.

The cloud holding the stars is quite a sight

The mammoth star cluster, described in a paper published in today's issue of the journal Nature, lies in an even more massive cloud of gas and dust that is part and parcel of NGC 5253, a dwarf galaxy located roughly 11 million light-years from us, in the constellation Centaurus.

Being still very young, the stars have not yet dispersed the gas and the dust that weren't used up in the processes that led to their formation. It is estimated that the mass of dust surrounding them and hiding them is about 15,000 times greater than that of the Sun.

“We are seeing the dust that the stars have created. Normally when we look at a star cluster, the stars long ago dispersed all their gas and dust, but in this cluster, we see the dust,” said University of California, Los Angeles physics and astronomy professor Jean Turner.

True, our Milky Way also packs massive clouds the size of the one that birthed these over one million stars. However, it looks like NGC 5253's cloud D, shown in the image below, is a tad more passionate about creating new cosmic fireballs than its siblings in our galaxy.

In the picture below, cloud D and the cluster lurking in its entrails are represented as the super bright spot at the center. The other bright spots around it are other young star clusters. The red and the fuzzy yellow, on the other hand, show the distribution of gas in this region of the dwarf galaxy.

It is estimated that, when compared to clouds of a similar size in the Milky Way, cloud D in neighboring dwarf galaxy NGC 5253 has a star-forming rate about 10 times higher. Hence the ginormous cluster now nestled deep inside it.

Of the stars lurking inside this cloud, about 7,000 are so-called O stars. What this means is that they are about one million times brighter than our Sun and among the brightest celestial bodies astronomers have until now had the chance to identify and study.

The stars inside it will eventually destroy the cloud

Cloud D's star cluster is believed to be about 3 million years old. This might sound like a whole lot of candles on its birthday cake, but when compared to the age of the universe, this makes it very young.

Of the stars included in this cluster, none has until now exploded in a supernova. However, such major explosions will eventually come to happen, and when they do, cloud D will likely be ripped apart.

Astronomers say that, following the destruction of the cloud, the dust and the gas in it, together with the elements pouring out of the dying stars, will be spilled into interstellar space.

Space image shows the cloud as a bright spot
Space image shows the cloud as a bright spot

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Mammoth cosmic cloud holds over one million stars
Space image shows the cloud as a bright spot
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