International Centre for Radio Astronomy Research | 2018 Sep 04
A radio telescope in outback Western Australia has been used to observe radiation from cosmic rays in two neighbouring galaxies, showing areas of star formation and echoes of past supernovae.A red, green, blue composite image of the Large Magellanic Cloud made from
radio wavelength observations at 123MHz, 181MHz and 227MHz. At these
wavelengths, emission from cosmic rays and the hot gases belonging to the
star forming regions and supernova remnants of the galaxy are visible.
The Murchison Widefield Array (MWA) telescope was able to map the Large Magellanic Cloud and Small Magellanic Cloud galaxies in unprecedented detail as they orbit around the Milky Way.
By observing the sky at very low frequencies, astronomers detected cosmic rays and hot gas in the two galaxies and identified patches where new stars are born and remnants from stellar explosions can be found. ...
International Centre for Radio Astronomy Research (ICRAR) astrophysicist Professor Lister Staveley-Smith said cosmic rays are very energetic charged particles that interact with magnetic fields to create radiation we can see with radio telescopes. "These cosmic rays actually originate in supernova remnants -- remnants from stars that exploded a long time ago," he said. "The supernova explosions they come from are related to very massive stars, much more massive than our own Sun. The number of cosmic rays that are produced depends on the rate of formation of these massive stars millions of years ago." ...
ICRAR astronomer Dr. Bi-Qing For, who led the research, said this was the first time the galaxies had been mapped in detail at such low radio frequencies. "Observing the Magellanic Clouds at these very low frequencies -- between 76 and 227MHz -- meant we could estimate the number of new stars being formed in these galaxies," she said. "We found that the rate of star formation in the Large Magellanic Cloud is roughly equivalent to one new star the mass of our Sun being produced every ten years. In the Small Magellanic Cloud, the rate of star formation is roughly equivalent to one new star the mass of our Sun every forty years." ...
A Multi-Frequency Radio Continuum Study of the Magellanic Clouds.
I. Overall Structure and Star Formation Rates ~ B-Q For et al
- Monthly Notices of the RAS 480(2):2743 (Oct 2018) DOI: 10.1093/mnras/sty1960