Saturday, June 12, 2021

The Fried Egg Galaxy

NGC 7742 (also known as UGC 12760) is a spiral galaxy, located at a distance of around 72 million light years in the constellation of Pegasus. It was discovered on the 18th of October 1784 by William Herschel.

This is a face-on spiral galaxy and due to its appearance it has been nicknamed the Fried Egg Galaxy. 

The galaxy belongs to the category of ring galaxies, thus it is unusual that it has no bar. The latter is needed in order to create a ring structure. Thus, astronomers have suggested an alternative scenario for the formation of the ring. According to the model the ring is the result of a merger with a dwarf galaxy that collided with NGC 7742. 

This is supported by the central bright region of the galaxy, the presence of a highly inclined central gas disk, together with gas that is counter-rotating with respect to the stars.

In terms of activity, this is a Type II Seyfert Galaxy, and it is believed that the galaxy hosts a supermassive hole at its heart that is currently active. Evidence for this, is the bright central component of the galaxy. 

Image: Composite optical image of NGC 7742 taken with the Hubble Space Telescope. The image was created using broadband filters that are centred at 336 nm (UV, blue), 555 nm (V-band, green), and 675 nm (R-band, red). Around the bright central core a dust belt is located, followed by a blueish region that is an area of star formation. Another dusty area with lower density surrounds the blue ring. The spiral arms of the galaxy start only after this region of NGC 7742.

Image Credit: Hubble Heritage Team (AURA/STScI/NASA/ESA)

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