Tiny Galaxy Discovered By Accident In Our ‘Cosmic Backyard’

ESA / Hubble, NASA, Bedin et al.(CC BY 4.0 )

Astronomers have just made an incredible discovery while scouring the sky with the Hubble Space Telescope. Hidden behind a distant star cluster, the scientists uncovered a never-before-seen dwarf galaxy located right in our “cosmic backyard.”

The news comes from NASA, which announced earlier today that the newfound galaxy is a “dwarf spheroidal galaxy that is as old as the universe.” The dwarf galaxy is very ancient, dating back to 13 billion years ago, and is located some 30 million light-years away — a stone’s throw in cosmic terms.

According to the Hubble Space Telescope website, the dwarf galaxy was found purely by chance. The credit goes to an international team of astronomers led by L.R. Bedin from the INAF-Astronomical Observatory of Padua in Italy. The scientists stumbled upon the dwarf galaxy while observing a globular star cluster called NGC 6752, which lies 13,000 light-years away in the halo of the Milky Way galaxy.

As the Inquisitr previously reported, globular clusters are spherical and extremely dense stellar bundles crammed with thousands of ancient stars that date back to the early days of the universe.

While looking at NGC 6752, the team initially spotted an odd group of stars that didn’t seem to belong to the globular cluster. After analyzing their brightness and temperature, the astronomers realized that the stars weren’t part of NGC 6752, but were actually located behind it — approximately 2,300 times farther out into the cosmos.

Hubble image of the Bedin 1 dwarf galaxy hidden among the stars of the NGC 6752 globular cluster.Featured image credit: NASA, ESA and L. Bedin (Astronomical Observatory of Padua, Italy)

The newly discovered dwarf galaxy has been dubbed Bedin 1. Nestled right on the doorstep of the Milky Way galaxy, the tiny Bedin 1 sports an elongated shape and measures just 3,000 light-years at its greatest extent. That puts the dwarf galaxy at just a fraction of the size of the Milky Way, barely one-thirtieth of our galaxy’s diameter.

In addition to being very old and very small, Bedin 1 is also incredibly faint. Compared to the Milky Way, its luster is 1,000 times dimmer. All of these characteristics have earned it the classification of dwarf spheroidal galaxy — a group of small galaxies with “low-luminosity, lack of dust, and old stellar populations,” explains the Hubble website.

“Thirty-six galaxies of this type are already known to exist in the Local Group of Galaxies, 22 of which are satellite galaxies of the Milky Way.”

Composite image showing the location of the Bedin 1 dwarf galaxy far behind the globular cluster NGC 6752.
Composite image showing the location of the Bedin 1 dwarf galaxy far behind the globular cluster NGC 6752.Featured image credit: NASA, ESA, L. Bedin (Astronomical Observatory of Padua, Italy) and Digitized Sky Survey 2

While this type of galaxy might be fairy common, Bedin 1 is one of the most fascinating of the bunch. The tiny galaxy ranks among a handful of dwarf spheroidals with a well-established distance. At the same time, the dwarf galaxy is extremely isolated — it lies 2 million light-years from the nearest major galaxy that might host it as a satellite, a large spiral galaxy called NGC 6744.

“This makes it possibly the most isolated small dwarf galaxy discovered to date.”

The video below uses real Hubble data to recreate the journey to Bedin 1 by way of an animation, one which shows the cosmic flight through the NGC 6752 globular cluster and all the way to the dwarf galaxy hidden behind it.

The uncommon features of Bedin 1 make the dwarf galaxy particularly interesting for study, said NASA.

“Because of its 13-billion-year-old age, and its isolation — which resulted in hardly any interaction with other galaxies — the dwarf is the astronomical equivalent of a living fossil from the early universe.”

The paper describing this amazing find can be read in the Monthly Notices of the Royal Astronomical Society: Letters.