New observations from ESO’s Very Large Telescope have revealed stars forming in the powerful outflows in galaxies, which are driven by central supermassive black holes.
Artist’s impression of a galaxy forming stars within powerful outflows of material blasted out from supermassive black holes at its core. Image credit: ESO / M. Kornmesser.
An international team of astronomers and astrophysicists used two VLT’s instruments — MUSE and X-shooter — to study an ongoing collision between two galaxies, known collectively as LEDA 70861, that lie approximately 600 million light-years from Earth.
The researchers observed the colossal winds of material (outflows) that originate near the supermassive black hole at the heart of the pair’s southern galaxy, and have found the first clear evidence that stars are being born within them.
“Astronomers have thought for a while that conditions within these outflows could be right for star formation, but no one has seen it actually happening as it’s a very difficult observation. Our results are exciting because they show unambiguously that stars are being created inside these outflows,” said team leader Roberto Maiolino, professor of experimental astrophysics at the University of Cambridge, UK.
The team set out to study stars in the outflow directly, as well as the gas that surrounds them.
By using the MUSE and X-shooter instruments, the scientists could carry out a very detailed study of the properties of the emitted light to determine its source.
Radiation from young stars is known to cause nearby gas clouds to glow in a particular way. The extreme sensitivity of X-shooter allowed the team to rule out other possible causes of this illumination, including gas shocks or the active nucleus of the galaxy.
The team then made an unmistakable direct detection of an infant stellar population in the outflow.
These stars are thought to be less than a few tens of millions of years old, and preliminary analysis suggests that they are hotter and brighter than stars formed in less extreme environments such as the galactic disc.
As further evidence, the researchers also determined the motion and velocity of these stars.
The light from most of the region’s stars indicates that they are traveling at very large velocities away from the galaxy center — as would make sense for objects caught in a stream of fast-moving material.
The discovery provides new and exciting information that could better our understanding of some astrophysics, including how certain galaxies obtain their shapes; how intergalactic space becomes enriched with heavy elements; and even from where unexplained cosmic infrared background radiation may arise.
“If star formation is really occurring in most galactic outflows, as some theories predict, then this would provide a completely new scenario for our understanding of galaxy evolution,” Prof. Maiolino said.
The findings were published today in the online edition of the journal Nature.
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R. Maiolino et al. Star formation inside a galactic outflow. Nature, published online March 27, 2017; doi: 10.1038/nature21677
This article is based on text provided by the European Space Agency.
