‘Red and dead’ galaxies that stopped forming stars in the distant past can sometimes come back to life, find two studies published in the journal Monthly Notices of the Royal Astronomical Society. Surface brightness map of the merging cluster CIZA J2242.8+5310. Scale bar – 1.63 million light-years. Image credit: G. A. Ogrean et al., arXiv: 1403.5273. According to structural formation hierarchy of the Universe, stars form galaxies and galaxies...
