Massive quiescent galaxy found in a distant protocluster

Using the Keck I telescope, Japanese astronomers have identified a massive quiescent galaxy in a distant galaxy protocluster known as SSA22. The galaxy, designated ADF22-QG1, turns out to be the most distant quiescent galaxy in a protocluster to date. The finding is reported in a paper published June 21 on the arXiv pre-print repository.