Hubble revealed strange blue ‘blobs’ of young stars

That astrophysicists working on the riddle of black fabric Searching for dwarf galaxies containing dark matter but which are probably very weak to have escaped previous detection. that standard cosmological model predicts the existence of a large number of these galaxies dwarfs around large galaxies such as The Milky Way.

It is possible to hunt these dwarf galaxies, and more generally faint galaxies close to our Galaxy using radio telescopes like those of the network of Very large array in New Mexico (USA). Technically, it is a matter of studying the radiation radio of clouds of gase.g via The known line 21 cm from hydrogen. Thus, several promising gas clouds that could be associated with faint dwarf galaxies have been discovered by the group ofastronomers led by Elizabeth Adams of the Dutch Institute of Radio Astronomy.

These gas clouds were thought to be connected to the Milky Way, and most of them probably are. But when teams – with scientists like David Sand, associate professor of astronomy at UArizona, or Michael Jones, postdoc researcher atUArizona Steward Observatory and lead author of an article on these clouds and deposited in free access on arXiv wanted to look for stars associated with them and dwarf galaxies, they had surprises.

Thus an unprecedented association of young blue stars forming a group called SECCO1 and observed with telescope Hubble was actually by chance ina cluster of galaxies of the Virgin. Located at an estimated distance of 48 to 72 millionlight yearsit was discovered by the famous French astronomer Charles Messier (1730-1817) known for having created the famous catalog of deep sky objects bearing his name.

Two hypotheses for the origin of the mysterious “blue blobs”

Other observations made with Hubble and the instruments from VLT of Eso in Chile has revealed the existence of ” blobs similar drawings with never before seen features. Thus, most stars in each system are very blue and very young, rich in heavy elements that astrophysicists call metals which in reality are simply other nuclei than those ofhydrogenI’helium and their isotopeall bathed in clouds containing very little atomic hydrogen that form well at the end of the structures the size of a dwarf galaxy.

The article regarding arXiv reports five blue “blobs” distant from the Milky Way and distant galaxies in the cluster of Virgowhich they are potentially associated with, from a distance of up to 300,000 light-years.

The presence almost exclusively of blue stars, therefore young, with no yellow dwarf Where red dwarf really detectable, indicates that star formation is new. However, the presence of many metals indicates that the gas from which these stars were formed must have been in a large and ancient galaxy, which had time to evolve chemically with several generations of stars performing nucleosynthesis stars and end their lives in supernovae, thus expelling the products of this nucleosynthesis in the galaxies. We should therefore see, as in the Milky Way, red dwarfs and yellow in abundance.

To solve this paradox, two theories can be invoked that all involve masses gas expelled from a large galaxy. The first assumes the effect of tidal forces exerted by a large galaxy on another, forces which would therefore have torn gas off. The second theory involves a galaxy rapidly colliding with a mass of hot plasma in the galaxy cluster. It can be shown that the shock produces one pressure able to quickly tear a lot of gas from the galaxy. We are then talking about an effect called stripping by dynamic pressure (frame pressure stripping English).

The scientists lean more towards the second hypothesis because in order to obtain blobs, after all, which is very isolated from the surrounding galaxies, they have to move fast, which is not compatible with the hypothesis of the mechanism of tidal forces.

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