"Last gasps": Exoplanet discovered dissolving particularly quickly
Exoplanets are already known to disintegrate slowly, but none as quickly as BD+05 4868 Ab. It loses one Mount Everest per orbit.
Artistic representation of the exoplanet
(Image: Jose-Luis Olivares, MIT)
A research group from the USA has discovered an exoplanet that is losing so much material in its close orbit around its star that it is trailing a comet-like tail half an orbit long. This was announced by the Massachusetts Institute of Technology (MIT), where the dying celestial body was discovered. It has about the same mass as Mercury, but is much closer to its star than the innermost planet in the solar system. The exoplanet with the designation BD+05 4868 Ab needs around 30 hours for one orbit and loses as much material as Mount Everest with each orbit. In one to two million years, it will have completely disintegrated.
A chance find
As the group explains, the disintegrating exoplanet was discovered “almost by chance”; they were not looking for it. They became aware of it in the data from the TESS space telescope because its signal looked unusual. The device searches for regular dimming of stars, which can be attributed to celestial bodies passing in front of them. However, these are normally brief, and the star quickly returns to its original brightness. In this case, however, it took much longer for the star to become as bright as before, and the intensity of the dimming kept changing. Overall, the signal resembled that of a comet with a long tail.
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Based on the orbital data and the unusual dimming, the team determined that it was probably a rocky planet with a tail up to nine million kilometers long. While the tail of a comet consisting mainly of gases and ice would not last long so close to a star, that of the exoplanet is probably made up of minerals. The celestial body itself is therefore likely to be around 1600 degrees Celsius hot, so any rock present there would boil and escape into space due to the planet's low mass. In principle, we are seeing the last breaths of the celestial body, its end is quite nearby astronomical standards.
Of the almost 6000 known exoplanets, BD+05 4868 Ab is not the first to disintegrate, the team writes. They know of three others, but none of them has a tail that is even remotely comparable in length, and none of them causes its star to dim to a comparable extent. This suggests that the situation of the celestial body is “most catastrophic, and it will disappear much faster” than the others, explains Marc Hon from MIT. Using the James Webb Space Telescope, his team wants to take the opportunity to determine the composition of the exoplanet based on its tail. The team also wants to search for further specimens. They present their discovery in the Astrophysical Journal Letters.
(mho)
