BBC:
Astronomers have now seen evidence that the central galaxy in a
huge galaxy cluster is making new stars at a surprisingly
vigorous rate. From their observations using 10 different
telescopes worldwide, the researchers estimate that the galaxy,
located in the Phoenix clusterâmdash;formally
known as SPT-CLJ2344-4243âmdash;is making
about 740 stars a year. Galaxy
clustersâmdash;the largest gravitationally
bound structures in the
universeâmdash;typically consist of hundreds
of galaxies orbiting their mutual center of mass. In most
clusters, the large galaxies closest to the center are believed
to have a central black hole surrounded by a lot of gas. While
the black hole's gravity draws material in, the black hole
itself releases huge amounts of energy that heats the gas,
resulting in what has been described as a tug of war. If,
however, the gas gets a chance to cool down, it can draw
together and start forming stars. The astronomers surmise that
the black hole at the core of the Phoenix cluster's central
galaxy must not be releasing as much energy, because they have
detected particularly bright emissions in the UV range,
indicating potentially hundreds of young stars.
