New “Blue Blob” Class Of Stellar System May Have Experienced A Galactic “Belly Flop”

New “Blue Blob” Class Of Stellar System May Have Experienced A Galactic “Belly Flop”

New “Blue Blob” Class Of Stellar System May Have Experienced A Galactic “Belly Flop”

New “Blue Blob” Class Of Stellar System May Have Experienced A Galactic “Belly Flop”

Astronomers have discovered a new class of galaxies, the blue blobs seen here by the Hubble Space Telescope Image Credit: Michael Jones

Astronomers have discovered a new class of galaxies. These collections, also called blue blobs, are rich in blue stars and are the size of small dwarf galaxies, although, unlike these, they don’t seem very close to a large galaxy.

That’s not all – the galaxies tend to lack older stars, suggesting they are very young systems, but they also lack atomic gas. Given the young age of the stars and the lack of atomic gas, this means that these blobs have lost some of their gas very recently.

One explanation the researchers prefer is that they did a cosmic belly flop (technically known as ram pressure stripping). The findings can be read in a paper available on the ArXiv.

“This is like falling into a swimming pool,” lead author Michael Jones, a postdoctoral researcher at the University of Arizona Steward Observatory, said in a statement. “When the belly of a galaxy falls into a cluster that is full of hot gas, the gas is forced behind it. That’s the mechanism we think we see here to create these objects.”

The research suggests that these systems move very quickly, consistent with observations that they are isolated from larger galaxies, and that they have lost most of their atomic gas while still retaining their molecular gas. The findings were presented at the 240th meeting of the American Astronomical Society, held last week in California.

The team did not look for strange congregations of stars. Their project looked at gas clouds near the Milky Way in hopes of finding new dwarf galaxies there, and followed up with findings from stars associated with these gas clouds. While many of these clouds are likely still near our galaxy, the first group of stars spotted in any of these clouds was ultimately in the Virgo cluster. Certainly not next to the Milky Way.

“It’s a lesson in the unexpected,” Jones said. “If you’re looking for things, you won’t necessarily find what you’re looking for, but you might find something else very interesting.”

Ram pressure stripping is considered an important process in galaxy evolution, as it can affect galaxies entering clusters after cluster collisions and other processes.

“We think this process of rolling up the belly turns many spiral galaxies into elliptical galaxies at some level, so learning more about the general process teaches us more about galaxy formation.”