Mysterious "Blue Blobs" Disclose a New Type of Star System in Galactic Belly Flop

 

The formation of the star formations is theorized to result from the collision of galaxies with hot gas, which is analogous to executing a belly flop in the water.

Five instances of a new type of star systems have been found by astronomers at the University of Arizona. They only exist in solitude and are not exactly galaxies.

Only young, blue stars are present in the new stellar systems, which are dispersed in an erratic manner and appear to reside in astonishment-inducing isolation from any putative parent galaxy.

The star systems are housed within the relatively close Virgo galaxy cluster and are described by scientists as appearing through a telescope as "blue blobs" and being around the size of small dwarf galaxies. It is difficult to pinpoint the origins of the five systems since, in some cases, they are more than 300,000 light years away from any putative parent galaxies.

The researchers discovered the new systems after a different study team, led by Elizabeth Adams of the Netherlands Institute for Radio Astronomy, created a list of prospective locations for new galaxies from neighboring gas clouds. Following the release of that catalog, numerous research teams, including one under the direction of David Sand, an associate professor of astronomy at the University of Arizona, began searching for stars that could be linked to those gas clouds.

The first cluster of stars, known as SECCO1, was discovered and astronomers realized it was not near the Milky Way at all, but rather in the Virgo cluster, which is much farther away but still relatively close in the scope of the universe. The gas clouds were initially thought to be associated with our own galaxy, and most of them probably are.

According to Michael Jones, a postdoctoral fellow at the University of Arizona Steward Observatory and the study's main author who described the new star systems, SECCO1 was one of the extremely uncommon "blue blobs." The research, which Sand and Jones co-authored, was presented by Jones on Wednesday at the 240th American Astronomical Society conference in Pasadena, California.

Jones remarked, "It's a lesson in the unexpected." You could come across something else that's really intriguing when you're looking for something, but you won't always find what you're looking for.

The team used the Very Large Array telescope in New Mexico, the Hubble Space Telescope, and the Very Large Telescope in Chile to gather its observations. A companion publication focussing on the Very Large Telescope data has been filed by study co-author Michele Bellazzini of the Italian institute Istituto Nazionale di Astrofisica. She oversaw the analysis of the data.

Together, the group discovered that the majority of the stars in each system are extremely young, very blue, and have very low levels of atomic hydrogen gas. This is essential because the initial phase of star formation involves atomic hydrogen gas, which eventually transforms into thick clouds of molecular hydrogen gas before developing into stars.

The majority of the systems, according to our observations, lack atomic gas, although molecular gas is still present, according to Jones. "In reality, they are still creating stars, therefore there must be some molecular gas. These systems must have recently lost their gas, as evidenced by the presence of predominantly young stars and minimal gas.

The absence of older stars in the systems as well as the presence of blue stars were surprising. The majority of galaxies include older stars, sometimes known as "red and dead" stars by astronomers.

Old red stars are typically the last ones still alive because they have a lesser mass at birth and so survive longer than blue stars, which burn quickly and experience early death, according to Jones. "And since they run out of gas to create new stars, they are also dead. Basically, these blue stars resemble an oasis in a dry desert.

The abundance of metals in the new star systems provides a clue as to how they could have developed.

According to Jones, "metals" are any element that is heavier than helium. Because metals are created through several, successive events of star formation, which are only actually possible in large galaxies, this indicates that the gas that made up these stellar systems was taken from a larger galaxy.

There are primarily two methods for removing gas from a galaxy. The first is tidal stripping, which takes place when two large galaxies cross paths and gravitationally suck away gas and stars.

The second is a process called ram pressure stripping.

Jones compared it as belly-flopping into a swimming pool. "A galaxy's gas is driven out from behind it when it flops into a cluster of hot gas. That is the method we believe to be at work here to produce these items.

The team favours the ram pressure stripping explanation because the tidal stripping process moves more slowly than ram pressure stripping, which is required for the blue blobs to become as isolated as they are.

These systems are expected to eventually separate into their own star clusters and disperse over the bigger galaxy cluster, according to astronomers.

According to Sand, what scientists have discovered contributes to a bigger "narrative of recycling of gas and stars in the cosmos." We believe that many spiral galaxies undergo some amount of transformation into elliptical galaxies during this belly-flopping phase, thus understanding the basic process helps us understand how galaxies develop.