• Mayur Pawar

Massive galaxies in the universe; Top 10 largest galaxies in the universe

Today we are going to introduce top 10 largest galaxies in the universe. There are about 200 billion galaxies in the universe and known galaxies are about 100 billion. A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The galaxies are divided into three types; elliptical, spiral, or irregular. Spiral galaxies consist of planets, stars, gas and dust. Elliptical galaxies consist of a large number of older stars, interstellar matter, and a very little dust. An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.

1. IC 1101 – 4,000,000 ly (1,200,000 pc)

IC 1101 is the largest known galaxy in the universe. It is about 4,000,000 light years away from Earth. It is super-massive elliptical galaxy at the center of the Abell 2029 galaxy cluster. It is one of the brightest galaxies known to us. This galaxy is consist of large number of metal-rich stars, although they are about 7 billion years older than the Sun. British astronomer Frederick William Herschel I discovered on 19 June, 1790. A ultra-massive black hole is at the center of this galaxy. As per one report it consist of 100 trillion (10^14) stars. It beautifully looks like yellow in colour. The stellar diameter of this galaxy is only 424,000 ± 78,000 ly.

Fig.1.01 IC 1101

2. Hercules A – 1,500,000 ly (460,000 pc)

Hercules A is super-giant elliptical galaxy. Hercules A is a bright astronomical radio source within the vicinity of the constellation Hercules. As the name Hercules A galaxy is occupied the 2nd place from our top 10 largest galaxies. This galaxy is about 1000 times more massive than our Milky way galaxy (approximately 1015 solar masses). The black hole at the center of this galaxy is largest known black hole to us. The stellar diameter of this galaxy is ‎479+26; −23 kly (147+8; −7 kpc).

Fig. 1.02 The central black hole is nearly 1,000 times more massive than the black hole at our Milky Way’s center

3. Abell 2261 – 1,000,000 ly (310,000 pc)

Abell 2261 is a huge elliptical galaxy, it has one million light year diameter. Abell 2261 is one of 25 galaxy clusters being studied as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) program, a major project to build a library of scientific data on lensing clusters. It is 10 times bigger than our Milky way galaxy. It has binding mass 2.9 ± 0.5×10^14 h^−1 0.70 M☉

Fig. 1.03 Abell 2261 by Hubble Space Telescope

4. ESO 306-17 – 1,000,000 ly (310,000 pc)

ESO 306-17 is a fossil group giant elliptical galaxy in the Columba constellation, about 1 million light-years in diameter, and 493 million light-years away. Apparent size is 2.5 arcsec . It appears that ESO 306-17 is surrounded by other galaxies but the bright galaxies at bottom left are thought to be in the foreground, not at the same distance in the sky. In reality, ESO 306-17 lies fairly abandoned in an enormous sea of dark matter and hot gas.

Fig. 1.04 ESO 306-17 by Hubble Space Telescope

5. UGC 2885 – 832,000 ly (255,000 pc)

UGC 2885 is a large unbarred spiral galaxy of type SA(rs)c in the constellation Perseus. This galaxy is one the largest known spiral galaxies in the universe. UGC 2885 is may be the possible member of Pisces-Perseus super-cluster. This galaxy can be observed by only infra-red wavelengths. Estimated diameter of UGC 2885 is about 832,000 light-years, approximately 8 times the diameter of our Milky way galaxy.

Fig. 1.05 UGC 2885

6. Comet Galaxy – 600,000 ly (180,000 pc)

The Comet Galaxy, a spiral galaxy located 3.2 billion light-years from Earth, was found with the Hubble Space Telescope. It rushes at 3.5 million km/h through the cluster Abell 2667 and therefore, like a comet, shows a tail, with a length of 600,000 light-years. Apparent magnitude of Comet galaxy is 18.7 V.

Fig. 1.06 The Comet Galaxy by the Hubble Space Telescope

7. Condor Galaxy – 522,000 ly (160,000 pc)

Condor Galaxy is placed 3rd place from our top 10 largest galaxies. Condor Galaxy, also known as NGC 6872, is a large barred spiral galaxy of type SB(s)b pec in the constellation Pavo. It is about 212 million light-years away from Earth and five billion years old. English astronomer John Herschel discovered Condor Galaxy on 27 June 1835. Mass of Condor galaxy is about >10^11 M☉.