ARP-116

Astronomy Photo of the Day: 12/09/14 — Arp 116

The galaxy in the upper right almost looks like it’s superimposed on an image of the large galaxy pictured front and center, but these galaxies are actually two pebbled floating nearby in a large, cosmic pond.

The larger of the two, called Messier 60, is an elliptical galaxy found about 54 million light-years from Earth, while the smaller one is NGC 4647. It’s a little more distant, situated around 63 million light-years from Earth.

Messier 60 spans an impressive 120,000 light-years across, which makes it about 20 percent larger than the Milky Way. Its brilliant, egg-like shape comes from a large number of older, more evolved stars, containing well over a trillion times the mass of the Sun.

NGC 4647 might be smaller, but it certainly has more character. This spiral galaxy spans about 90,000 light-years across, and its appearance is the result of young, hot, blue-white stars; a mix of interstellar gas and dust; and numerous winding spiral arms that form a flattened disk.

Collectively, they are known as Arp 116. Both galaxies belong to the Virgo Galaxy Cluster. In this particular group, all objects have the tendency to collect on the eastern side, which explains why they are so close together, while they are nearly 10 million light-years apart (The Milky Way is separated from its closest neighbor by nearly 2.5 million light-years, for comparison).

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Image Credit: NASA/ESA

Arp 116

Arp 116 is a galaxy pair consisting of elliptical galaxy Messier 60 and smaller spiral galaxy NGC 4647. Messier 60 is located about 55 million light years from Earth in the Virgo cluster of galaxies. NGC 4647 is located about 63 million light years away.

Messier 60 is the third brightest galaxy in the Virgo cluster, a collection of over 1,300 galaxies. It has a diameter of 120,000 light years, a mass about one trillion times our sun, and contains one of the most massive black holes ever discovered. NGC 4647 is about two thirds the size of Messier 60 and has a mass about equal to the Milky Way.

Astronomers have tried to determine whether the two galaxies, relatively close to each other, interact, but have not found evidence of stars forming between the two, the clearest sign of interactions between galaxies. However, recent studies have indicated there may be some gravitational interaction between the two.

Image from National Geographic, information from National Geographic and NASA.