Science is always discovering and never give anything (or almost) by attended, Football It is a demonstration: the star is in fact exploded thousands of years ago on the edge of the Milky Waywhere astronomers have always considered these phenomena decidedly unlikely. The discovery, the result of a research guided by the National Institute of Astrophysics (INAF) and fromUniversity of Palermocould change what has always been thought to be theevolution of our galaxy.
To over 6500 light years above the plane of the Milky Way, where the density of stars thinks and the interstellar void dominates, the extreme system subject to the study challenges the rules of the stellar evolution: a rare rest of Supernova associated with a pulsar on the run, known with the name of Calvera – a tribute to the antagonist of the film “I Magnifici 7”, a western film of the 1960 directed by John Sturges – – Like his cinematic homonymous, Calvera moves to the margins, outside the rules, and is rewriting what we know about the life and death of the massive stars in the most extreme regions of our galaxy
The story of Calvera
In 2022, the radiotelescendo Lofar – a European network of RadioTelescopi designed to observe the sky at low frequencies – identifies a Extended and almost perfectly circular structurethat astronomers interpret as a rest of supernova.
It is located about 37 degrees of galactic latitude, therefore very far from the galaxy plan, where the star explosions. But “near” (for cosmic distances), there is a pulsar already known to astronomers also for his intense emission in X -rayswho had been called Calvera.
The “problem” lies in this unusual disposition, because Calvera seems to be a potential companion of the rest of Supernova. And not only that: his trajectory shows a very marked motion, which, according to astronomers, indicates one “Escape” from the center of the explosion.
The picture that emerges is that of a physical link between the two objects: a massive star exploded thousands of years ago, which has left behind an expanding gas shell and a star of neutron on the run
What has just been discovered (and how)
The researchers have now analyzed the data obtained with the satellite XMM-NEWTON ofEuropean Space Agency (ESA). In particular, the properties of hot gas within the rest of Supernova, combined with the pulsar motion and the information collected by different tools, have allowed to estimate age and distance of the system
The calculations have shown that the rest of Supernova is located at a distance between 13,000 and 16,500 light years, and that it is between 10,000 and 20,000 years: the data are perfectly compatible with those of the pulsar, and this strengthens the hypothesis of an ‘common origin.
The massive stars, that is, with mass at least eight times larger than the sun, are formed almost exclusively on the galactic level, where the density of the gas is higher and promotes the star birth – explains Emanuele Greco, the first author of the study – finding the remains of such distances from the plan is extremely rare. Our analysis made it possible to more precision the distance, the age and even the characteristics of the possible progenitor star that originated both the Calde Pulsar and its rest of Supernova
Among other things, the system is in a very different environment from that typical of the galactic plan: In fact, so far it has always been thought that to activate one of the main production mechanisms of the range radiation, high density of particles are necessary, especially of protons, while those detected now come from an area where this density is far from high.
In practice, even in the “suburbs” of the galaxies, decidedly rarefied, the sufficient conditions can exist ad Activate intense energy mechanismscapable of producing range emission efficiently.
Thanks to space telescopes such as XMM-Newton and Fermi/Lat, and terrestrial tools such as the Galileo national telescope, we can analyze the remains of Supernova and the pulsar in different gangs of the electromagnetic spectrum. In the case of Calvera, we have shown that even in rarefied environments there may be plasma to millions of degrees, if the shock wave of the explosion meets local thickenings. These thickening, in turn, tell something about the evolutionary history of the star that has exploded
And this is much more than a scientific curiosity, it could really rewrite Everything we have always thought aboutEvolution of the Milky Way.
The work was published on Astronomy & Astrophysics.
Sources: Inf / Astronomy & Astrophysics
