14 DAY TRIAL // Experts with the Astronomical Observatory of the Jagiellonian University in Poland and the Astronomical Institute at the Ruhr-University Bochum, Germany, announce the discovery of a new galaxy neighboring the Milky Way. The object has not yet been named, but its discoverers say that it lies in the Lew Triplet (the M66 Group), some 35 million light-years away, in the constellation Leo.
Scientists say that this object is cataloged as a tidal dwarf galaxy, meaning that it most likely formed from the tidal waves released by its larger counterparts, including the Milky Way. Galaxies in this class are believed to be produced following collisions between two or more massive galaxies. Such events rip apart streams of material from both galaxies, as well as some dark matter halos.
These clouds of stars – featuring entire solar systems, nebulae, supernovae, and more – then take on the shape of a new galaxy, complete with its own core, but still bearing the scars of the huge tidal forces that created it. The Milky Way is known as an avid collector of such dwarf galaxies, totaling no less than 20 dwarf galaxies in its orbit, Technology reports.
Some astronomers suggest that the large globular cluster Omega Centauri may in fact be a dwarf galaxy featuring a massive black hole at its core. The standalone nature of Omega Centauri has yet to be confirmed or infirmed satisfactorily, but the possibility that it was once a galaxy onto itself remains.
Upon studying the yet unnamed tidal dwarf galaxy, the Polish research team determined that this is the closest object of its class to the Milky Way. What is particularly interesting about these cosmic structures is that the nature of their formation process precludes them from gobbling up too much dark matter from their predecessors.
As such, tidal galaxies are renowned for their high ratio of baryonic matter to dark matter. The former is the stuff that makes up all stars and galaxies we can observe in the Universe. Dark matter is invisible and only interacts with regular matter via gravity. Since these galaxies are very small, they cannot exert a sufficiently strong gravitational pull to keep too much dark matter within.
Astronomers with the joint team say that they will continue studying the newly-discovered tidal galaxy, explaining that objects in this class are in the habit of forming from stars that originated in the older, outer parts of their initial host galaxies. For example, the stars in this galaxy that were once in the Milky Way were located in the outer rings of our galaxy before they were snatched up.
Discovering the new tidal dwarf galaxy was made possible by the use of the Very Large Array (VLA) new Socorro, New Mexico, and by analyzing data from the Sloan Digital Sky Survey (SDSS). The latter is conducted by the Apache Point Observatory, also in New Mexico. Additional details of the new study appear in the preprint journal arXiv.