In the first survey of the sky with the eROSITA X-ray telescope, astronomers at the Max Planck Institute for Extraterrestrial Physics identified a previously unknown Hoing supernova remnant.
The discovery was confirmed by radio archive data and marks the first opening of a joint partnership between Australia and eROSITA. It is designed to explore the Milky Way galaxy using multiple wavelengths, from low-frequency radio waves to energetic X-rays. The Hoing supernova remnant is very large and located far from the galactic plane.
Massive stars end their lives in giant supernova explosions when their fusion processes no longer generate enough energy to withstand their gravitational collapse. But even with hundreds of billions of stars in the galaxy, these events are fairly rare. Astronomers estimate that in our Milky Way, a supernova event should occur on average every 30-50 years. Although the supernova itself can only be observed for several months, their remnants can be detected even after 100 thousand years. These remnants are made up of material ejected by the exploding star at high velocity and which is propelled when it collides with the surrounding interstellar medium.
Today there are about 300 known such supernova remnants that should be observed throughout our galaxy. In fact, there should be more than 1,200 of them. So, either astrophysicists have misunderstood the frequency of supernovae occurrence, or the vast majority of them have not yet been taken into account. An international team of astronomers is now using the eROSITA X-ray telescope to scan the entire sky to search for previously unknown supernova remnants. At temperatures of millions of degrees, the debris of such supernovae emit high-energy radiation. That is, they should be displayed in high quality X-ray data.
After astronomers found the object in eROSITA’s all-sky data, they turned to other resources to confirm its nature. Hoeing is almost invisible and no one has noticed it before due to its location at high galactic latitude. Confirmation of its existence came from radio data – the spectral range in which 90% of all known supernova remnants have been discovered so far.