Hubble revealed strange blue “blobs” of young stars

That astrophysicist Work on the riddle of black matter are looking for dwarf galaxies that contain dark matter but are likely very faint to have escaped previous detection. the Standard Cosmological Model predicts the existence of a large number of these galaxies Dwarfs around large galaxies like that Milky Way.

It is possible to hunt these dwarf galaxies and more generally faint galaxies near our galaxy with radio telescopes like that of the network of Very large array in New Mexico (USA). Technically, it’s about studying the radiation radio from Clouds from gasfor example above the famous line 21 cm away from hydrogen. Several promising gas clouds that could be associated with faint dwarf galaxies were therefore discovered by the group ofastronomers led by Elizabeth Adams from the Netherlands Institute for Radio Astronomy.

These gas clouds were thought to be associated with the Milky Way, and most of them probably are. But when teams — with researchers like David Sand, associate professor of astronomy at UArizona, or Michael Jones, a postdoctoral researcher at theUArizona Steward Observatory and lead author of an article on these clouds and deposited in open access arXiv – wanted to search Stars Associated with them and dwarf galaxies, they had surprises.

Thus was born an unprecedented union of young blue stars that formed a group SECCO1 and observed telescope Hubble actually happened to be in thegalaxy cluster the virgin. Located at an estimated distance between 48 and 72 millionlight yearsit was discovered by the famous French astronomer Karl Messier (1730-1817) famous for creating the famous catalog of deep sky objects that bears his name.

Two hypotheses on the origin of the mysterious “Blue Blobs”

Other observations made with Hubble and the VLT of Eso in Chile have the existence of ” blobs similar blueprints with never-before-seen features. Therefore, most of the stars in each system are very blue and very young, rich in what astrophysicists call heavy elements metals they are in fact simply different cores than those of thehydrogenI’helium and your isotopesall immersed in clouds containing very little atomic hydrogen, which forms well at the end of structures the size of a dwarf galaxy.

The article on arXiv reports five blobs of blue distant from the Milky Way and distant galaxies in the cluster Virgowith which they may be associated, from a distance of up to 300,000 light-years.

The presence almost exclusively of blue stars, hence young, with No Yellow Dwarf Where red dwarf truly detectable, suggests star formation is recent. 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 that has had time to chemically evolve, performing multiple generations of stars nucleosynthesis stellar and end their lives in supernovae, thereby propelling the products of this nucleosynthesis into the galaxies. We should therefore see, as in the Milky Way, Red Dwarfs and yellow in abundance.

To resolve this paradox, two theories can be used, all of which play a role crowds Gas ejected from a large galaxy. The first takes the effect of tidal forces exerted by one large galaxy on another, forces that would therefore have ripped off gas. The other theory involves a galaxy rapidly colliding with a mass of hot plasma in the galaxy cluster. It can be shown that the shock produces a Print able to quickly tear a mass of gas out of the galaxy. We then speak of an effect called stripping by dynamic pressure (ram pressure scraper in English).

The researchers are more inclined towards the second hypothesis, because in order to obtain blobs, which are nevertheless very isolated from the surrounding galaxies, they must move quickly, which is inconsistent with the hypothesis of the tidal mechanism.

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