2023-08-28 17:21:32
Tidal rupture events are cosmic catastrophes that occur when a star passes too close to a supermassive black hole. Simple theory in the early 1980s, they are observed and dissected with the gaze of X-ray telescopes in space. We have just specified the composition and the mass of the star which was destroyed in this way behind a supernova named ASASSN-14li.
As Futura has reminded many times, it was in March 1982 that Jean-Pierre Luminet and Brandon Carter exhibited in the newspaper Nature the theory implying that a star entering the area defined by the tidal radius of a supermassive black hole must first be flattened like a pancake by tidal forces. In a second step, they explained, thermonuclear reactions had to occur within the star, leading to detonations capable of dislocating it, which led to the phenomenon now known as tidal disruption events, or TDE in English. In practice, the phenomenon of rupture event by tidal effect, as we say in French, was to be signaled first by the appearance of a supernova, then by the emission of X-rays by the gas of the star forming an accretion disk around the black hole before it partially swallows it.
Futura had also explained in a previous article that on November 22, 2014, automated telescopes observing on Haleakalā, a volcano on the island of Maui (Hawaii), as part of the program All-Sky Automated Survey for Supernovae (ASAS-SN), had flushed out a transient light source in the visible. baptized ASASSN-14li, it was soon observed more closely in the X-ray domain by a trio of well-known space telescopes, NASA’s Chandra and Swift, and ESA’s XMM-Newton. The analyzes showed that it was precisely the destruction of a star by the tidal forces of a supermassive black hole which it approached too closely. The event occurred in the galaxy PGC 043234, located regarding 290 million light-years from the Milky Way, in the direction of the constellation Berenike’s Hair.
The TDE of a star of three solar masses
Studies of ASASSN-14li have continued since then, and today a paper published in The Astrophysical Journal Letters reports new analyzes once more obtained in the field of X-rays with the Chandra orbiting telescopes of NASA and XMM-Newton of ESA.
These analyzes provide new constraints on the composition of the star destroyed by a supermassive black hole by removing a previous ambiguity. We were not certain that the abundances of carbon and nitrogen nuclei determined were not in fact rather a reflection of the composition of the environment of the black hole, of the gas supplied by previous TDEs or of the filaments of cold matter. , rather than the reflection of the material ejection produced by the destruction of the star behind ASASSN-14li.
As explained, in a NASA statement regarding the Chandra and XMM Newton observations, astrophysicist Brenna Mockler of the Carnegie Observatories and the University of California at Los Angeles, “ these X-ray telescopes can be used as forensic tools in space. The relative amount of nitrogen to carbon we found indicates material from inside the doomed star weighed regarding three times the mass of the Sun. ».
How to explore galactic nuclei with TDEs – Brenna Mockler. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Institute for Advanced Study
This makes this star to date one of the most massive – and possibly the most massive – that astrophysicists have seen so far torn apart by TDE.
In the same press release, Enrico Ramirez-Ruiz of the University of California at Santa Cruz, who also participated with his colleague in the study of ASASSN-14li, declared that this TDE is ” exciting because one of the hardest things with TDEs is being able to measure the mass of the unlucky star, as we did here. Watching the destruction of a massive star by a supermassive black hole is spellbinding, as more massive stars are expected to be significantly less common than lower-mass stars. ».
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