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Barnard's Galaxy | by Nicolas ROLLAND
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Barnard's Galaxy

Barnard's Galaxy (NGC 6822) is a dwarf irregular galaxy in the constellation Sagittarius. About 1.6 million light-years away, it is one of the closer galaxies to the Milky Way, and a member of the Local Group. It is similar in structure and composition to the Small Magellanic Cloud.

 

NGC 6822 was the first galaxy beyond the Magellanic Clouds to have its distance accurately determined.

 

More peculiar, however, is NGC 6822's unusually high abundance of HII regions - locales of ionized hydrogen that surround young stars. Today, there are over 150 of these regions cataloged in Barnard's Galaxy. La plus grande région de formation d’étoiles actuellement active dans NGC 6822 est appelée Hubble-X. This bright, nearly circular cloud at the core of Hubble-X measures about 110 light-years across. It contains a central cluster of many thousands of young stars, less than 4 million years old. A bluish arm of loosely-grouped young stars extends outward.

 

In the 1920s, Hubble found three star clusters in Barnard's Galaxy that he believed were all very old objects similar to the Milky Way's globular clusters. However, images taken by the Hubble Space Telescope have shown that these clusters are of completely different ages. The stars in the cluster called Hubble VII were formed about 15 billion years ago, and are about the same age as the Universe itself. A second cluster known as Hubble-VIII contains stars about 1.8 billion years old; while a third cluster, Hubble VI, has stars that are as young as 100 million years.

 

It seems that, unlike the Milky Way (whose big globular clusters mostly formed in the first few billion years after the Big Bang), Barnard’s Galaxy has been generating massive, new star clusters all along.

 

RA: 19h 46m 05.55s

DEC: -14° 45' 01.0"

Location: Sagittarius

Distance: 1600 kly

Magnitude: 9.34

 

Acquisition August 2020

Total acquisition time of 32.5 hours.

 

Technical Details

Data acquisition: Martin PUGH

Processing: Nicolas ROLLAND

Location: El Sauce Observatory, Rio Hurtado, Chile

L 16 x 1200 sec

R 14 x 1200 sec

G 14 x 1200 sec

B 19 x 1200 sec

Ha 23 x 1800 sec

Optics: Planewave 17“ CDK @ F6.8

Mount: Paramount ME

CCD: SBIG STXL-11002 (AOX)

Pre Processing: CCDstack & Pixinsight

Post Processing: Photoshop CC

 

Text source : Livesky.com

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Uploaded on October 27, 2020