Quadruple Star System Found | NASA Discovery

In the immensity of the cosmos, the solitude of our Sun is almost an anomaly, because the majority of stars listed live in pairs. The TIC system 120362137, details of which have just been published in Nature Communicationsshatters the banality of binary systems.

Here we are faced with a quadruple hierarchy of record compactness, a stellar clockwork mechanism nestled in a ridiculously small volume of space on an astronomical scale.

The TESS space observatory sets out to track down the tiny

To flush out this monster of complexity, the researchers did not use a giant telescope on the ground, but the Transiting Exoplanet Survey Satellite, aka TESS, from NASA. Originally designed to detect exoplanets via the transit method, that is to say the observation of the drop in luminosity when a star passes in front of its star, TESS stands out here as an absolute stellar metrology tool.

Thanks to the analysis of light curves — these variations in brightness of the order of a few fractions of a percent — the intelligence of the algorithms and the perseverance of the astronomers made it possible to dissect the signal. Now it was not a planet which obscured a star, but a ballet of mutual eclipses between four stars. A technological feat capable of isolating the signatures of each member within a system where everything seems to be intertwined.

“Crazy” architecture: a ballet of three stars squeezed in the orbit of Mercury

The originality of TIC 120362137 lies in its so-called “3+1” hierarchical organization. Imagine a core composed of an inner trio composed of an extremely tight binary orbited by a third star at a distance equivalent to that of Mercury from our Sun. This central trio is itself orbited by a fourth star located at a distance less than that of Jupiter.

It is the most compact system of this type ever observed and this proximity involves gravitational interactions of rare violence. The tidal forces are indeed so powerful that they dictate rapid and inevitable evolution, far from the dead calm that our solar system experiences.

These stars will devour each other

The study does not just photograph the present moment; it also projects this system into a cataclysmic future. Currently on the main sequence, that is to say in full possession of their means, these stars will inevitably age.

The two main stars, those in very tight orbits, “weigh” 1.75 and 1.36 solar masses respectively. These are white stars with a temperature of around 6300°C, or 800°C hotter than our Sun. These two main components orbit each other in just 3.28 days, while the third orbits them in 51 days, and the last in 1045 days.

In a few million years, the members of the inner trio will swell to become red giants. Because of the extreme compactness of the system, their gas envelopes will eventually touch and merge. This process, called “common envelope evolution,” will result in spectacular stellar mergers.

The study thus makes projections based on reasonable hypotheses. One possibility is that in about 270 million years, the three closest stars will have merged into a body of about four solar masses.

At the end of this veritable gravitational feast, the system will lose a large part of its mass in the form of stellar wind, leaving behind only corpses of stars: white dwarfs. In short, what is today a four-part choir will transform into a dark and dense ballet of carbon and oxygen residue.

Why is this astronomical discovery important?

Beyond the performance of TESS, TIC 120362137 is a Rosetta stone for astrophysicists. It makes it possible to test the limits of orbital stability and to refine our models on the end of life of multiple stars. For us observers, it is a reminder that the Universe is a machine for producing the improbable, provided we have the tools sensitive enough to look at it.

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