Scientists spotted enormous ghost galaxy hiding next to the Milky Way

A galaxy a third the size of our own, but extremely faint, has been observed orbiting around the Milky Way.

Top image: G. Torrealba (Academia Sinica, Taiwan), V. Belokurov (Cambridge, UK and CCA, New York, US) based on the image by ESO/S. Brunier
Top image: G. Torrealba (Academia Sinica, Taiwan), V. Belokurov (Cambridge, UK and CCA, New York, US) based on the image by ESO/S. Brunier

A universal group, including an astronomer from Imperial College London, found the massive galaxy while trawling through information from the European Space Agency’s Gaia satellite. The galaxy named  Antlia 2 (or Ant 2) has not very many stars, testing ordinary hypotheses of galaxy formation.

Ant 2 is known as a dwarf galaxy. As structures developed in the early Universe, smaller people were the principal cosmic systems to frame, thus the majority of their stars are presently old, moderately low as far as their mass, and poor in metals.

Current speculations of galaxy formation can’t completely clear how a world so huge has so few stars. Past research has proposed that a few smaller people could be swelled by vigorous star arrangement, making the cosmic system ‘puff up’, yet the new research demonstrates that this process would need to be strikingly proficient to clarify Ant 2.

Then again, the properties of the tricky ‘dark matter’, thought to keep worlds together, might be reconsidered. The as of now supported hypothesis predicts that dim issue packs firmly in the focuses of cosmic systems, however a dark matter molecule which is less quick to the group might be required.

 V. Belokurov and A. Smith (Cambridge, UK and CCA, New York, US) based on the images by Marcus and Gail Davies and Robert Gendler
V. Belokurov and A. Smith (Cambridge, UK and CCA, New York, US) based on the images by Marcus and Gail Davies and Robert Gendler

In this new study, scientists searched the new Gaia data looking for Milky Way satellites by using RR Lyrae stars. These stars are old and metal-poor, typical of those found in dwarf galaxies.

The ESA’s Gaia mission has delivered the most extravagant star list to date, including high-precision estimations of almost 1.7 billion stars and uncovering already inconspicuous points of interest of our home world. Prior this year, Gaia’s second information discharge made new points of interest of stars in the Milky Way accessible to researchers around the world.

Lead creator Gabriel Torrealba, from the Institute of Astronomy and Astrophysics at Academia Sinica in Taipei, Taiwan, stated: “This is a ghost of a galaxy. Objects as diffuse as Ant 2 have simply not been seen before. Our discovery was only possible thanks to the quality of the Gaia data.”

The group could affirm that the ghostly object they spotted was real by checking with associates at the Anglo-Australian Telescope (AAT) in Australia, which demonstrated that all the stars were moving together. The specialists were likewise ready to gauge the world’s mass, which was much lower than anticipated for a protest of its size.

Dr Geringer-Sameth said: “Antlia 2 certainly gives a reason for optimism. One of the many great things about Gaia is that it surveys the entire sky. I love the idea that the next discovery may already be waiting for us in the public archive of Gaia data. We just have to learn how to spot it.”

The other authors of the study include Gaia DR2’ by G. Torrealba, V. Belokurov, S. E. Koposov, T. S. Li, M. G. Walker, J. L. Sanders, A. Geringer-Sameth, D. B. Zucker, K. Kuehn, N. W. Evans2 and W. Dehnen.

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