Mysterious ‘blue blobs’: new type of galaxy discovered full of young blue stars

The blue blobs don’t last long, but they are spectacular. Scientists discovered as many as five galaxies with these young blue stars.

Scientists at the University of Arizona argue that the blue galaxies are fundamentally different from the previously known types. They are full of young, blue stars and are surprisingly far away from other galaxies.

The isolated “blue blobs,” as astronomers affectionately call them, are relatively small. The five star nebulae are the size of a small dwarf system and are located in the Virgo Cluster. Potential neighbors are more than 300,000 light-years away, making it difficult to figure out how they formed.

Dutch discovery
The discovery was made possible in part by the Netherlands Institute for Radio Astronomy (ASTRON). Led by researcher Elizabeth Adams, a wealth of information has been obtained about gas clouds – the birthplaces of stars – in the universe. Using this data, a list was made of potential new galaxies and their location. After this ASTRON catalog was published, various research groups ran off with the data. For example, David Sand, an astronomy professor at the University of Arizona, and his team searched for special stars in these interstellar gas clouds.

Sand thought he was looking at gas clouds in our own Milky Way galaxy, but some star clusters, such as SECCO1, turned out not to be located around the corner at all. To their surprise, the mysterious blue nebulae were far away in the Virgo Cluster.

“SECCO1 is a very special blue bubble,” said Michael Jones, an expert on young galaxies at the Steward Observatory in Arizona. “In our profession it is important to be open-minded. Expect the unexpected. When you investigate, you don’t always find what you were looking for. Sometimes you come across something completely different, which turns out to be extremely interesting.” That turned out to be the case in this case.

H1 and H2

The team analyzed data from Hubble and the large space telescopes of New Mexico and Chile. Together they concluded that most of the stars in these new galaxies are very young and very blue. What is also remarkable is that there is almost no atomic hydrogen gas (H1) present in the stars. This is fascinating, because a star is normally formed under the influence of atomic hydrogen. This is slowly converted into thick clouds of molecular hydrogen gas (H2) before the star takes shape. “We see that these galaxies contain hardly any atomic hydrogen, but that doesn’t mean it isn’t there. It has to be, as stars are still forming. The existence of the young stars and the lack of gas means that they have recently lost their gas,” Jones said.

“Red stars have a smaller mass and therefore live longer than blue stars. They burn hard and die quickly. Red stars fade, blue stars churn out all the fuel at a rapid rate, leaving them with no gas to form new stars. They’re like desert oases,” Jones explains the differences between the two star types.

It seems that the blue galaxies have taken their fuel, consisting of molecular gas clouds, from other galaxies. Since the nearest galaxies are hundreds of thousands of light-years away, it probably came with a big bang and a lot of speed.