Galaxies

Diagram showing the Andromeda galaxy, the halo that surrounds it and how its size was measured (Image NASA/STScI)

A team of scientists used the Hubble Space Telescope to measure the extent of the halo of the gas surrounds the Andromeda galaxy. It turned out to be much larger than expected stretching for about a million light-years from the galaxy. This means it reaches out to about half the distance that separates it from the Milky Way so if it was visible to the naked eye its size would be about a hundred times that of the full Moon. The results of this research were published in “Astrophysical Journal”.

Scheme of a three-body interaction in which a galaxy is turned into a compat elliptical then is ejected from a cluster (Image NASA, ESA, and the Hubble Heritage Team)

There are several known cases of runaway stars such as Zeta Ophiuchi but now the Russian astronomers Igor Chilingarian and Ivan Zolotukhin of the Moscow State University’s Sternberg Astronomical Institute have found runaway galaxies. In an article published in the journal “Science”, the list 11 galaxies ejected from the clusters they used to be part of because of the gravitational interaction with their neighbors.

Images of eight galaxies containing green filaments that are the last effect of ancient quasars (Image NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa))

The Hubble Space Telescope photographed a series of ghosts of quasars that existed in the past. They are seen as ethereal green objects in various forms and are the last effects of ancient quasars. These phenomena are very interesting from a scientific standpoint because they can provide information about the past of those galaxies, which were once very active.

The Planck all-sky map at submillimetre wavelengths with the protoclusters indicated as black dots. The inset images showcase some of the observations made by Herschel’s SPIRE instrument (Image ESA and the Planck Collaboration/ H. Dole, D. Guéry & G. Hurier, IAS/University Paris-Sud/CNRS/CNES)

An article published in the journal “Astronomy & Astrophysics” describes the results of a research carried out by combining the observations made with ESA’s Herschel and Planck space telescopes. The purpose was to find protoclusters, the precursors of today’s galaxy clusters seen in the distant past when the universe was only three billion years. This will help to understand how these huge groups of tens, hundreds and even thousands of galaxies formed and evolved.