Faintest Satellite Galaxy Of The Milky Way Has Been Discovered

Posted: Nov 22 2016, 7:37am CST | by , Updated: Nov 22 2016, 8:56pm CST, in News | Latest Science News

 

Faintest Satellite Galaxy of the Milky Way has been Discovered
Credit: Tohoku University/National Astronomical Observation of Japan
 

Astronomers have found an extremely faint dwarf galaxy in the halo of the Milky Way, which may be the faintest satellite galaxy ever found.

Astronomers have discovered an extremely faint satellite galaxy orbiting around Milky Way. The satellite galaxy, named Virgo I, lies in the direction of constellation Virgo and it could be the faintest ever found in our region of the universe.

The discovery suggests that there could be many more such galaxies out there yet to be found. If detected, these dwarf satellites could provide important clues into the formation of our galaxy Milky Way.

“This discovery implies hundreds of faint dwarf satellites waiting to be discovered in the halo of the Milky Way,” said researcher Masashi Chiba from Tohoku University. “How many satellites are indeed there and what properties they have, will give us an important clue of understanding how the Milky Way formed and how dark matter contributed to it.”

The galaxy was discovered using powerful 8.2m Subaru Telescope and is one of those galaxies detected during recent Subaru Strategic Survey. Overall, some 50 satellite galaxies have been identified in the Milky Way. Most of them are faint and belong to a category of dwarf spheroidal galaxies – a group of ultra-faint dwarf galaxies that are accompanied by Milky Way. However, previous surveys have detected only those satellites that were relatively close to the Sun or were having higher magnitudes, leaving out the more distant or faint ones.

The Subaru Telescope alongside its Hyper Suprime-Cam (HSC) instrument has made it possible for researchers to spot even the most faint satellite galaxies that were lurking in deep space.  

“Surprisingly, this is one of the faintest satellites, with absolute magnitude of -0.8 in the optical waveband,” said Daisuke Homma, one of the researchers involved in the study.

“This is indeed a galaxy, because it is spatially extended with a radius of 124 light years – systematically larger than a globular cluster with comparable luminosity.”

The newfound satellite galaxy is located at the distance of 280,000 light years away from our solar system but whether it is the faintest ever, it’s yet to be confirmed. If it turned out the way researchers expect, it will beat the previous known faintest dwarf satellite Segue I, discovered by Sloan Digital Sky Survey (SDSS) and Cetus II. SDSS had also surveyed the same area in the direction of constellation Virgo but could not detect Virgo I.

The current Subaru Strategic Survey will continue to explore much wider area of the sky and is expected to find more satellites like Virgo I that could provide more insight in the formation of galaxy Milky Way.

 

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Hira Bashir covers daily affairs around the world.

 

 

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