Astronomers have found a new type of star system in which clusters of young, hot, blue stars are formed out of gas in a galaxy.
That sentence is wonderful.
While these stellar systems were found on purpose, they turned out not to be what the astronomer had in mind, adding a little bit more fun to the whole story.
The Local Group is made up of a few dozen nearby galaxies, and we live in the biggest of them. There are a lot of small, fast moving clouds of atomic hydrogen gas in the sky that are thought to be part of the Local Group. Astronomers thought the clouds could be forming stars.
Initial visible-light observations were not very illuminating. They were just like blobs. One cloud showed it was forming stars. The Counterpart of Compact high-velocity clouds is known as SECCO-1. This wasn't part of the Local Group, but part of the Virgo Cluster, which is 60 million light years away.
There is a lot of gas in the Virgo Cluster. Encouraged by the initial results, more observations of the hydrogen clouds were made using a number of telescopes. The GALEX observatory shows ultraviolet emission in gas clouds that are likely to be star formation.
Five such clouds were targeted by them. A knot of distant background galaxies was the one that turned out to be. The Hubble telescope showed the clumps of stars in space. They can't prove they are part of the cluster, but their brightness and speeds are consistent with that. They seem to be inside the cluster.
What are they? They aren't normal. The objects have warm hydrogen gas in them and are clumpy. The stars are blue to indicate they are young and large. Only one of them, BC 3, appears to have a lot of this gas, while the rest are deficient in it.
The systems are young and they don't have bright red stars. Red giants are formed when stars like the Sun die. It may only take tens of millions of years for a massive star. These systems are young.
They have less than 100,000 times the amount of stars in them. Even though it sounds like a lot, the universe has millions or billions of solar mass in it. These objects are several thousand to 20,000 light-years long and are not as small.
What are they, what are they? Gas clouds floating around in space don't collapse to form these These are between galaxies in a huge cluster.
It makes a big difference. Galaxies in the cluster are all in the same position. A gas-rich galaxy plunging through the cluster can move at speeds of hundreds of kilometers per second, millions of kilometers per hour, and when they do they experience a lot of pressure by the thin gas between galaxies. The same way you can air out a car by opening the windows, this can strip out the gas inside a fast- moving space station. ram pressure stripping is a kind of thing.
There is a lot of this going on in the Virgo cluster, and some of the galaxies are losing a lot of gas. As the gas is blown back and moved behind the parent galaxy, it can become stars. This would explain why the new systems are relatively isolated and why they are a natural result of plowing through the gas within the cluster. Their parents left them behind.
Their fate is to be dissolved after they formed. Over time, the stars in these systems will fly away and become isolated stars in the Virgo cluster. The lifetime of the stellar clusters is shorter than the lifetime of the galaxy cluster. As gas is stripped from the galaxies, these systems are likely to form continuously. If there was a single short-term event that made these objects, then they would have dissipated a long time ago.
These are a new type of star cluster if all this is true. Formed as gas is ripped from galaxies, they eventually evaporate, peppering the cluster with millions of rogue stars.
That shows that we still have a lot to learn about how stars are made. We only saw these objects because they are nearby, and in more distant clusters they wouldn't be visible with current technology.
It's too far away to look at what's happening in the corners of the universe.
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