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Discovery of ‘fluffiest’ ever galaxies baffle scientists

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Astronomers are baffled by a recent discovery of ‘fluffiest’ ever galaxies nearly as wide as our Milky Way galaxy some 300 million light-years away because of their puffed up nature. Researchers are looking for answers to questions about the origins of these galaxies and whether they were once successful star nurseries that ended up like the way they are now.

The discovery was made by an international team of researchers led by Pieter van Dokkum at Yale University using the W. M. Keck Observatory and published in the Astrophysical Journal Letters. The surprising bit about these galaxies is that despite their enormous size like our Milky Way, they only pack 1 per cent as many stars.

Astronomers combined results from one of the world’s smallest telescopes as well as the largest telescope on Earth to confirm their latest discovery. Using the Dragonfly Telephoto Array and its 14-centimeter state of the art telephoto lens cameras, the researchers produced digital images of the very faint, diffuse objects. Then using the Keck Observatory’s 10-meter Keck I telescope and its Low Resolution Imaging Spectrograph, they separated the light of one of the objects into colors that diagnose its composition and distance.

Researchers reveal that the distance was what seal the deal for them. The data from Keck Observatory showed the diffuse “blobs” are very large and very far away, about 300 million light-years, rather than small and close by. The blobs can now safely be called Ultra Diffuse Galaxies (UDGs).

Comparing the newly discovered galaxies with the Milky Way, van Dokkum said that if we consider our galaxy as a sea of stars, then the newly discovered galaxies are like wisps of clouds.

“We are beginning to form some ideas about how they were born and it’s remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter ‘shields’ that are protecting them from this intergalactic assault”, added van Dokkum.

Researchers found the UDGs in an area of the sky called the Coma cluster, where thousands of galaxies have been drawn together in a mutual gravitational dance.

“Our fluffy objects add to the great diversity of galaxies that were previously known, from giant ellipticals that outshine the Milky Way, to ultra compact dwarfs,” said University of California, Santa Cruz Professor Jean Brodie.

According to Roberto Abraham, of the University of Toronto, one of the biggest challenges for them is to figure out where these mysterious objects came from and whether they are ‘failed galaxies’ that started off well and then ran out of gas?

Abraham added that questions such as were they once normal galaxies that got knocked around so much inside the Coma cluster that they puffed up? Or are they bits of galaxies that were pulled off and then got lost in space? also remain to be answered.

The key next step in understanding UDGs is to pin down exactly how much dark matter they have. Making this measurement will be even more challenging than the latest work.