Hot Jupiters are exoplanets that are approximately the size of Jupiter, but orbit their respective star at a short distance, in extreme cases, it only takes 18 Earth hours to complete a full orbit. This means that they tend to be extremely hot, hence their name.
Many questions remain about how they form or how they move over time. Do they get close to or escape from their parent star during its life cycle?
A new study published in the Astronomical magazine Today it describes a new discovery of an extremely young and hot Jupiter-class exoplanet called HIP 67522 b, about 490 light years from Earth.
Its well-studied mother star is only 17 million years old, making the newly discovered planet several million years younger. That makes it the youngest of its kind ever found and could shed some light on the unique characteristics of hot Jupiters.
The discovery was made using NASA’s Transit Exoplanet Study Satellite (TESS), which can measure the decrease in brightness emanating from the star as the planet passes between us and its star.
HIP 67522 b is approximately ten times the diameter of Earth, suggesting that it is a planet dominated by gases, just like Jupiter.
Astronomers suggest there could be three different reasons why hot Jupiters ended up so close to their star. Either they formed on the spot, an extremely improbable hypothesis, or they slowly approached their star over time.
Its inward migration could have started this migration when it is still protected by the disk of gas and dust surrounding a newborn star system. Or, the third hypothesis, they were forced there when the gravity of other planets might have brought them closer later in the life of the star system.
However, the latter hypothesis seems less likely (although it has not been completely ruled out) with the discovery of HIP 67522 b, since it is very young.
“Scientists would like to know if there is a dominant mechanism that makes up most hot Jupiters,” Yasuhiro Hasegawa, an astrophysicist at NASA’s Jet Propulsion Laboratory who was not involved in the research, said in a statement. “At the moment there is no clear consensus in the community about which formation hypothesis is most important for reproducing the population we have observed.”
“The discovery of this hot young Jupiter is exciting, but it is only a clue to the answer,” he added. “To solve the mystery, we will need more.”
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