Sunday, September 19, 2021

The Devil's Mask

The Devil’s Mask (also known as KTS 59) is a galactic triplet in the constellation of Pavo, and it is part of the IC 4845 group. It was discovered on the 11 of August 1836 by John Herschel. Its three members are known as NGC 6769-71.

NGC 6769 (also known as PGC 63042) is a spiral barred galaxy, located at a distance of around 160 million light years. The galaxy has a diameter of around 110,000 light years.

The second member of the triplet (i.e., NGC 6770, also known as PGC 63048) is also a spiral barred galaxy, located at a distance of 160 million light years. The galaxy is slightly more extended and it is around 115,000 light years across.

The third member is NGC 6771 (also known as PGC 63049). This is a lenticular galaxy at a distance of 187 million light years. In terms of size this is the largest of three, being around 130,000 light years across.

NGC 6769 and NGC 6770 are clearly interacting, which has resulted in bursts of star formation on both galaxies. Due to this, both galaxies have a bluish appearance. The spiral arm of NGC 6770 that points towards NGC 6769 appears really bright, since star formation has a significantly higher rate there. Gas and stars from both galaxies have been stripped forming a common cocoon among them. 

Further noteworthy features of the triplet are, the tight spiral arms of NGC 6769, while the two spiral arms of NGC 6770 are way more distinct. Furthermore, NGC 6770 has two straight dust lanes that go across the northeastern region of the galaxy. Finally, a dust lane goes through NGC 6771.

Image: Composite optical image of the NGC 6769-71 triplet taken with ESO’s Very Large Telescope at Paranal, Chile. The image was created using broadband filters that are centred at 380 nm (U-band, blue), 425 nm (B-band, green), and 550 nm (V-band, red). NGC 6769 is at the top right of the image, while NGC 6770 is at the top left. Finally, NGC 6771 is at the bottom of the triplet.

Image Credit: ESO

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