Abell 2029

Abell 2029 or A2029 is a large cluster of galaxies 1 billion light years away in the constellation Virgo.Chandra X-ray Observatory, "Galaxy clusters and dark energy: Chandrao opens new line of investigation on dark energy", Harvard-Smithsonian Center for Astrophysics. 

Its central galaxy, IC 1101, is the largest galaxy known. Estimates ranging from 5.6 to over 6 million light years across. Contrast this with the Milky Way, which is 200,000 light years across. 

A2029 is also about 81 times bigger than the Milky Way, with a luminosity of 2 L☉. This type of galaxy may have grown to its large size by accreting nearby galaxies.

 References 

Other websites

The Scale of the Universe (Astronomy Picture of the Day 2012 March 12)
 Curious About Astronomy?, "What is the largest galaxy?", Cornell University

Category:Galaxy clusters