Published: Sun, February 03, 2019
Research | By Raquel Erickson

Starstruck astronomers accidentally discover hidden galaxy right next to Milky Way

Starstruck astronomers accidentally discover hidden galaxy right next to Milky Way

Of the estimated two trillion galaxies in the universe, NASA just located another one. completely by accident.

The cluster of small stars along the left of this photo is the newly discovered galaxy, Bedin I, while the large stars in the foreground belong to globular cluster NGC 6752. An worldwide team of astronomers was using Hubble's Advanced Camera for Surveys instrument to study white dwarfs - superdense stellar corpses - in the globular cluster NGC 6752, which is part of the Milky Way. And after carefully measuring the brightness and temperature of the background stars, they realized they had found something special - an entire galaxy that was hidden by the glare of NGC 6752.

The researchers published their findings online today (Jan. 31) in the journal Monthly Notices of the Royal Astronomical Society: Letters. WFIRST is a telescope specifically created to scan large chunks of the sky with the same resolution as Hubble, so there's a much better chance images from WFIRST could help us find even more sneaky galaxies once it's launched early next decade. For starters, it's small.

Only a fraction of the size of the Milky Way and incredibly faint, the so-called Bedin 1 system is considered a dwarf spheroidal galaxy-defined by their small size, low luminosity, and lack of dust and old stellar populations.

"It measures only around 3,000 light-years at its greatest extent (barely 1/30th the diameter of the Milky Way)", NASA said.

But Bedin 1 stands out from the crowd. They're also fairly common in our Local Group of galaxies - we know of 36 galaxies of this type and 22 of them are in orbit around our galaxy! By comparison, the Milky Way's length is 105,000 light-years.

Bedin 1 is so old and so distant that it has hardly interacted with any other galaxies meaning it's essentially "the astronomical equivalent of a living fossil from the early Universe", according to the Hubble team. The researchers suspect that Bedin-1 is the most isolated galaxy ever discovered.

"From the properties of its stars, astronomers were able to infer that the galaxy is around 13 billion years old - almost as old as the universe itself", Hubble team members wrote in a statement. It's thought that Bedin 1 is the most isolated dwarf galaxy known to exist.

In the 1990s, the famous Hubble Deep Field image led NASA to believe there were about 200 billion galaxies in the universe.

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