A new possibility has arisen for giant black hole formation: Massive gas clouds in a galaxy may be able to collapse directly into a black hole without stopping to become a star first. Galaxy CR7 shows evidence that this process could be the mechanism for young galaxies in the early universe to create supermassive black holes.
Galaxy CR7 also presents the best evidence for the existence of what are known as Population III stars—extremely metal-poor stars that would represent the earliest formed stars in the universe. Metal-poor refers to the composition as being almost entirely hydrogen and helium, with perhaps a trace of lithium – the only elements available in the universe at such an early stage – because stars had not been around long enough yet to produce heavier elements in supernova explosions.
This weekend, the moon and Jupiter will swap spots in the sky right after sunset. Then on subsequent days next week, the moon sweeps past Mars and Saturn. In coming weeks, Venus and Mercury will join this trio.
Image: ESO/M. Kornmesser