Astronomers have discovered a hypothetical “alien star” in space

toWith a mass three-quarters the size of our Sun, concentrated into a sphere that can sit comfortably within the beautiful city of Nice, compact object XMMU J173203.3-344518 is quite remarkable, even strange.

A new study by astrophysicists from the University of São Paulo and the Federal University ABC in Brazil confirms that this incredibly dense blob of stellar matter may be unusual, but perhaps not in the way you might think.

Last year, researchers from the Institute for Astronomy and Astrophysics at the University of Tübingen, Germany, They reassessed the distance that separates us from the tiny corpse of a dead star orbiting within the supernova remnant HESS J1731-347.

With a distance of only 8,150 light-years, the re-evaluated proximity is lower than the previous estimate, which was about 10,000 light-years away. The new distance required a new calculation of the properties of the compressed object, in particular its volume and mass. This is where things get more exciting.

When stars of a certain mass run out of fuel that their gravity could easily crush, they collapse in a cosmic thunderclap of heat and electromagnetism that washes away part of their outer layers. What remains is an object so dense that its atoms are pressed against each other. In the core of this body, electrons accumulate in the nuclei, forcing the protons to lose their charge and turn into neutrons. Here’s one neutron star who was just born.

If the mass is sufficient, all that extra gravity overcomes the critical nuclear forces to grind matter into something unimaginable, creating a black hole. On the other hand, if the mass is very low, the atoms remain friendly neighbors within a so-called a white dwarf.

The minimum mass of a neutron star is estimated to be just over one solar mass. The lightest object yet discovered weighs only 1.17 times the mass of the Sun. At 77% of the solar mass, XMMU J173203.3-344518 isn’t just a record, it’s absolutely baffling. Neutron stars aren’t supposed to be that small. Which means it might not be a neutron star. Assuming it was instead an object called ” strange starconsists mainly of particles called strange quarksThe researchers left it to other researchers to draw their conclusions.

Picking up where that last study left off, this new research looked at the unusually small compact object HESS J1731-347 and re-examined its mass, radius and surface temperature. By comparing his results with Eqs Strange And theoretical models for their creation in supernovaethe team agreed that this strange little object had all the characteristics of a hypothetical alien star.

If enough energy is concentrated in one place, these bundles of quarks can overcome the forces that bind them and arrange themselves to form something less orderly. Put that hot soup under enough pressure, and its quarks can form into a new form of matter called, unsurprisingly, Quark matter.

Quarks come in different shapes or flavours. The “up” and “lower” flavors mix together to form protons and neutrons. With enough pressure, the down quarks can turn into quarkswhich in turn can transform into another flavour, a strange quark.

Neutron star and quark star. (CXC / M. Weiss)

It is not yet known exactly how a superglued object consisting mostly of strange quarks arises from a supernova, although some models suggest that quark matter has evolved since the beginning of the collapse. Under very special circumstances, something causes this matter to take hold, releasing more energy as it collapses to shed more mass than normal, leaving behind that surplus of quarks.

Returning to the last study, the updated estimates of the age and surface temperature of XMMU J173203.3-344518, as well as the object’s small radius and mass, are consistent with cooling conditions, suggesting an odd composition. This does not mean that one can rule out something more “normal”. This gives the astronomy community yet another reason to switch their telescopes to XMMU J173203.3-344518, because this is a distinct case.

As the researchers stated:

It is too early to claim a stronger conclusion, though this is an important case and other discoveries could complement the big picture.

The study has been published in Astronomy and Astrophysics Letters and is available for preliminary printing at arXiv: A light alien star in remnant HESS J1731-347: minimal consistency checks.