It’s amazing what could be lying out there in space, obscured by the limitations of our eyes, our technology, and our preconceptions.
Astronomers have not just discovered the remains of a completely colossal supernova, a growing cloud of dust and gas left over from a stellar explosion, taking up an area of the skies nearly 100 times larger than the full Moon ( from our point of view), at maximum speed. of 4,000 light-years from Earth.
A team of astronauts led by Werner Becker from the Max Planck Institute for Extra-German Physics has named the rest of Hoinga, after the medieval name of Becker town.
How could we lose? The reason it is only visible in X-rays, and only to one of the most powerful X-ray telescopes we have built to date, is the space-based eROSITA that was launched in 2019.
(eROSITA / MPE (X-ray) / CHIPASS / SPASS / N. Hurley-Walker, ICRAR-Curtin)
Above: X-ray and radio combination of Hoinga.
“The eROSITA telescope, which is aboard the Russian-German SRG satellite, is 25 times more sensitive than the previous ROSAT, so we expected to discover new supernova remains in the coming years, but it surprised us that someone was showing up immediately, “he said. astronaut Natasha Hurley-Walker from the Curtin University node of the International Center for Radio Astronomy Research in Australia.
“Adding to our excitement, Hoinga is the rest of the supernova ever discovered through X-rays, apparently in size: about 90 times larger than the full Moon.”
Supernovae have two main motivational factors. One death is the death of a giant star. When they run out of material to melt in their corrugations, the reduction in external thermal pressure means that the pressure is no longer enough to keep the star from falling under the weight of its coils. -in, and the whole thing goes kaboom, sinking the heart into a neutron star or black hole (or eliminating it completely).
The other stimulant is a type Ia supernova, in which a white-tailed star – a low-mass progenitor falling star – pulls so much material from a binary partner that it becomes unstable, and becomes one end.
In each case, an expanding shell of the star’s outer material is blasted into space, creating shock-absorbing faces where it enters the intersex medium. That is the remnant of a supernova.
Most of the stars in the Milky Way are low-volume – it is estimated that 90 percent of the stars are main-series dwarfs that do not end in a supernova (stars that are currently “living” binding the nuclei of the hearts), and another 9 per cent of them are dead white fingers.
So while there are about 100 billion stars in the Milky Way, supernovae eruptions are very rare; astronomers estimate that it should fade away every 30 to 50 years, leaving a vibrant, vibrant cloud that lasts around 100,000 years.
An artist’s impression of a supernova. (ESA / Hubble, CC BY 4.0)
At that point, there should be about 1,200 supernova remnants currently available in the Milky Way; but we only know of 300 or so. This means that we either have the calculation of it, or were unable to find it, for any reason. This is where eROSITA comes in.
Most celestial objects emit X-radiation, invisible to the naked eye. EROSITA, designed to perform full-space analysis, is much more sensitive than before, and has featured X-ray objects that we have never seen before.
The remains of a previously unknown supernova should be discovered by eROSITA, but nonetheless, Hoinga was a surprise, not only because it was discovered so quickly, but because of where it was discovered. – far from the galactic plane, where most of the Milky Way stars (and therefore supernova remnants) lived.
The team double-checked their findings against radio astronomy data, and found weak evidence of Hoinga dating back ten years. It even appeared largely in ROSAT data taken 30 years ago.
“By sifting through archived radio data we found that Hoinga had been sitting there waiting to be discovered in studies up to ten years old, but because he was high above the Milky Way plane, was missed, “Hurley-Walker explained.
“Supernova remains are not normally expected to be found at high Galactic levels, so these areas are not usually the focus of studies, meaning that even more of what is left of it could be waiting to find out. “
Based on that radio data, the team calculated that the remains are between 21,000 and 150,000 years old (but perhaps at the younger end of that range), and are relatively small. near Earth, between 1,470 and 3,915 light-years away.
They were also unable to locate the remains of the progenitor star, suggesting that the explosion was type Ia. This is consistent with space, too, since large stars tend to focus in the galactic plane.
EROSITA conducts eight full-scale studies. The team hopes that data from future studies will help Hoinga’s nature – and find many more of the ‘missing’ supernovae at Milky Way.
The team’s research is expected to feature Astronomy & Astronomy, and is available on arXiv.