spaceSpace and Physics

Astronomers Finally See The Faint Swirling Halo Surrounding An Active Galaxy


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockMar 28 2017, 17:32 UTC

The Sculpture galaxy seen in optical (green) and radio (red) with active star formation region highlighted (blue). A.D. Kapinska, G. Meurer. ICRAR/UWA/CAASTRO.

Thanks to technological advancement, we can now use starburst galaxies – those that form lots of stars – to see the faint space environment around the galaxies themselves.

An international team of researchers have used the Murchison Widefield Array (MWA), a telescope in western Australia, to study NGC 253 – also known as the Sculptor galaxy. The goal was simply to see what’s happening in Sculptor’s galactic halo, the region that surrounds the galaxy disk.


In the study, published in the Astrophysical Journal, the team discuss the incredible set of observations they were able to obtain. Sculptor, which is located 11.5 million light-years away, appears to have an enormous halo of gas and dust that is blown out of the galaxies by supernovae explosions and strong winds coming from the galaxy core.

“We could see radio emission from electrons accelerated by supernova explosions spiralling in magnetic fields, and absorption by dense electron-ion plasma clouds – it’s absolutely fascinating,” lead researcher Dr Anna Kapinska, from The University of Western Australia and the International Centre for Radio Astronomy Research, said in a statement.

The MWA and this work is a precursor to the Square Kilometer Array (SKA), which will look farther and in more detail at the radio universe. The Sculptor galaxy was selected to better understand the type of galaxies we might look at with SKA.


These objects are known as starburst galaxies because they are forming many stars every year, and while we understand some of their properties, we are yet to know everything, especially what the right conditions are to make galaxies have a bout of star formation.

NGC 253 is particularly helpful in this. It is very close in cosmic terms and is a star factory, producing five stars the mass of our Sun every year, which is many times faster than our own galaxy.

The study is part of a project called GLEAM (GaLactic and Extragalactic All-sky MWA) that was set out in 2013 to provide astronomers with detailed observations of the sky in radio waves.


“With the GLEAM survey we were able, for the first time, to see this galaxy in its full glory with unprecedented sensitivity at low radio frequencies,” added Dr Kapinska.

Galaxy halos tend to contain hot gas and a few stars, but it is usually too rarefied to be observed in detail. Hopefully, studies like this can bridge the gap in our knowledge.

spaceSpace and Physics
  • tag
  • star formation,

  • galaxy evolution,

  • Galactic Halo