COLLIER CITIZEN

Looking Up: Devil’s Mask – A trio of distant galaxies

Ted Wolfe
Columnist

A trio of distant galaxies form a curious appearance – like a carnival mask. The two at the top would be the eyes with the one below shaped like a curved mouth. Thus the nickname “Devil’s Mask” for this group of cosmic fellow travelers.

The objects are found in the southern hemisphere of “Pavo,” the peacock. This constellation is not ancient. The drawing of a peacock constellation in the sky first appeared on a celestial globe published by the map maker Petrus Plancius in Amsterdam in 1598.

A trio of distant galaxies form a curious appearance – like a carnival mask. The two at the top would be the eyes with the one below shaped like a curved mouth. Thus the nickname “Devil’s Mask” for this group of cosmic fellow travelers.

Plancius was working off the star observations made by the Dutch traders Pieter Keyser, and Frederick de Houtman, who had sailed on the first Dutch trading expedition to the East Indies. Nearby in the night sky are the constellations of the Phoenix, Grus (crane), and Tucana (toucan). Collectively, the 4 constellations are referred to as the “Southern Birds.”

The three galaxies lie at a tremendous distance – some 190 million light years from the earth. It took that long for their light to reach us so we are looking at them as they appeared 190 million years ago. As we can see from the picture the galaxies are undergoing turmoil as they interact with each other.

Let’s meet the players. The top left galaxy is NGC 6769. The one next to it (forming the “Devil’s right eye”) is NGC 6770, while the bottom one is NGC 6771. When the New General Catalogue (NGC) was drawn up it endeavored to rather consecutively list deep space objects based on their position in the night sky’s co-ordinates. At some great time in the future all 3 will have merged so astronomers will probably designate the surviving galaxy with only one NGC number -freeing up the other twp numbers.

Large galaxies are formed out of the merger (a pretty violent occurrence) of smaller ones. Prior to the final event they tend to circle each other, like some sort of cosmic mating dance, finally succumbing to the gravitational pull which causes a final collision.

During their pre-collision “dance” things get pretty messy. Note the one on the top left, NGC 6769. Its beautiful, spiral shape has been wrecked by the pulling out of one of its arms - which is now pointing across to the galaxy on the right (NGC 6770). In fact, the arm has almost made contact with the other galaxy.

Now notice that both galaxies are surrounded by a misty envelope. This is the gas, dust and stars already stripped from the two galaxies. In fact, the argument could be made that the two are already one galaxy.

The pinkish features that can be found scattered through the two galaxies is evidence of intense new star formation, in reaction to the strong gravitational effects already sweeping through them as the merger looms on the horizon.

The third galaxy at the bottom also shows evidence that it too is already caught in the misty envelope, and is exchanging material back and forth between it.

These are violent, chaotic times for the 3 galaxies shown here and its only going to get worse. It brings to mind the early lines of Macbeth, when the three witches discuss their next meeting. “When shall we three meet again – in thunder, lightning or in rain?”

More:Looking Up: A strange encounter in deep space

Wolfe is a member of the Everglades Astronomical Society. Organized in 1981 it serves the Naples community providing information in all aspects of amateur astronomy. Its goals include educating the general public, school children, and other groups to the wonders of the universe. The Society meets at 7PM every 2nd Tuesday of the month at the Norris Center (public invited). Regular viewing visits to a special, dark sky site in the Everglades are held each month, allowing the general public to observe the night sky through telescopes, under pristine conditions. For more information visit the website at: http://naples.net/clubs/eas.