Whenever an astronomer looks up at the night sky, they are not just seeking things we already know about. They also look up there for signs of things that we believe should exist but just have not been discovered just yet. And when you stop and consider all the different factors that exist — such as the infinity of space itself, the amount of time we have searched, and the existing quality of the instrumentation we use — there are a multitude of things we should be seeing but for whatever reason, we just have seen them quite yet.
Rare Sights Make them Harder to Find
And the rarer such things are, the harder it will be to find them in the universe. But it just so happens that we might have discovered one of the hardest things there is to find recently. And this is a rare neutron star that was created when two white dwarf stars collided.
A star that lacks the mass to become a neutron star (which is damn near every one of them) are believed to end their life as a white dwarf. White dwarfs are merely stellar remnants that are made up of very dense degenerate matter. They typically have a maximum stable mass of around 1.44 M☉, which is roughly equal to 1.4 solar masses. This is referred to as the infamous Chandrasekhar limit. A white dwarf that manages to acquire the mass required to exceed 1.44 M☉ is big enough that the electron degeneracy pressure at the core of the star’s core will no longer resist its own gravitational self-attraction. When this happens, the star will implode and turn into either a neutron star or black hole, in a classic Type 1a supernova.
Well at least that is what is supposed to take place. What scientists discovered is actually a stellar object, J005311, which has some extremely rare characteristics. It is a very bright star in the infrared nestled within a gas cloud, therefore showing no visible light. It is roughly 40,000 times brighter than our sun (in infrared) and creates an intensive stellar wind, at 16,000km/s. Normal solar wind speeds coming off the biggest stars are somewhere around 2,000km/s, to provide a benchmark for how rapidly this crazy star is spinning.
“First of all, [these results show] that white dwarf mergers happen,” study co-author Götz Gräfener, who is an astronomer from the University of Bonn recently said. “And secondly, it shows that some of these mergers don’t explode.”
Whenever a star reaches the end stages of its lifetime, it starts fusing materials other than hydrogen. As to which materials it can fuse will be determined by its own density. Therefore, the collision of these two white dwarfs drastically boosted up the total density of the final star, which allowed for the fusing of heavier elements. This activity would usually develop a runaway fusion situation here that normally blows stars apart, but that is not what occurred in this case. Instead, this collision created sufficient heat to allow for the ignition of non-explosive carbon. And since the star is burning, it is creating enough thermal pressure to ward off any collapse and supernova that would’ve typically occurred. Needless to say, this is amazingly rare when compared to any expected behavior for a typical pair of white dwarfs that have collided.
The current speed and temperature of the winds that are blowing around J005311 indicate that it is probably at the end of its life. With its existing mass believed to be somewhere above the Chandrasekhar limit with an expected lifespan of only thousands of years, there is a great chance that we actually caught J005311 during the tiny span of time when we might be able to observe it. Whenever this star blows up, it will probably create a subluminous Type 1c supernova.