It has a mass almost three times that of Jupiter (and a size 1.8 times greater) and it is impossible for any form of life to exist due to its extremely high temperatures that make its atmosphere even boiling. This exoplanet is an ultra-hot Jupiter, that is, a huge gaseous world that can orbit its stars at distances that we would consider terrible, due to their proximity. We know about hot Jupiters, but KELT-9b is one step beyond this temperature: it is an ultra-hot, extremely scorching Jupiter. It was first discovered by researchers using the Kilodegree Extremely Little Telescope (KELT) at the Winer Observatory in southeastern Arizona, which detects dips in the brightness of a star and, in turn, suggests an exoplanet crossed in front of the star.
The hottest planet known so far
Its temperatures are around 4,700 ºC, so it is hotter there than in most known stars (it has a temperature similar to that of our Sun, which is 5,500 ºC): it is the absolute fire of hell. Now, new research published in The American Astronomical Society has revealed another very interesting detail about this unusual world: the metal vapor molecules found in its atmosphere shouldn’t be there. They cannot withstand such extreme heat. But there they are, something that could give us more information about what happens on this hot planet and even how it came into being.
“This planet reminds me of the mythical Icarus, who approached the sun and burned,” says Thomas Henning, co-author of the study and director of the Max Planck Institute for Astronomy. “Our planet will not crash into the Sun, but it will certainly lose an essential part of itself, namely its atmosphere.”
The planet orbits a star that is twice as hot as the Sun, at a distance ten times closer than that separating the planet Mercury from our star. It barely takes a day and a half on Earth to complete the orbit and it sports a gigantic and glowing tail of gas as if it were a comet. Not surprisingly, it is subject to a very strong gravitational attraction from its star, which is why it is blocked by tides; the same face of the planet is continuously looking at its star, resulting in completely opposite temperatures on the day and night sides of the planet. The point is, only one side of the planet is going through a perpetual sauna.
Earth could not withstand the pressure experienced by KELT-9b. Its atmosphere is a deadly cauldron of molecular hydrogen, metal oxides and hydrides , which could never exist in our cosmic territory. In fact, it is so close to the big star that the unusual thing is that it did not vaporize instantly.
If the metals present in your atmosphere should not exist because of the high temperatures, what happens?
The heat from the daytime side could destroy the molecules, as the theory goes, but not the atoms they are made of. If the winds sweep those atoms to the much cooler night side, and they join together again to form the same types of molecules that they formed before, it could explain why they were detected in an atmosphere that would otherwise be impossible for them to be present. Finding out how many of these metals are in KELT-9b’s atmosphere can tell us where it came from and how it got to where it is.
“This suggests that some important physical processes are taking place, and that our traditional predictions for this planet may not be as accurate, but it is still too early to tell,” the authors clarify.
Apart from this, the researchers expose that the gas escaping from its boiling atmosphere is being captured by its host star. This may mean that it was once a larger world, which over time suffered tremendous atmospheric loss. Perhaps it could even be a rocky core left over from a giant planet. The possible scenarios are many.
Taking into account that the Hubble telescope is already “older” for these tasks, astronomers will have to wait to study exoplanet atmospheres at other new-generation telescopes such as the long-awaited Jamess Webb, whose launch is scheduled for October 2021.
A Decade of Radial-velocity Monitoring of Vega and New Limits on the Presence of Planets Spencer A. Hurt, Samuel N. Quinn, David W. Latham, Andrew Vanderburg, Gilbert A. Esquerdo, Michael L. Calkins, Perry Berlind2, Ruth Angus, Christian A. Latham, and George Zhou. Published 2021 March 2 • © 2021. The American Astronomical Society. All rights reserved. The Astronomical Journal, Volume 161, Number 4 Citation Spencer A. Hurt et al 2021 AJ 161 157
