Astronomers have discovered a young planet outside the solar system resembling an infant that is shrinking rapidly due to its close proximity to its parent star, which is emitting a large amount of X-rays, tearing apart its atmosphere at an astonishing rate.
According to the National Aeronautics and Space Administration (NASA), through its Chandra X-ray Observatory, astronomers observed the exoplanet named TOI 1227 b shrinking from its current state of a Jupiter-sized planet with a thick atmosphere to a small and barren planet over the years.
TOI 1227 b’s parent star is a red dwarf star located approximately 330 light-years away from Earth. The planet orbits very close to its parent star, less than one-fifth of the distance between Mercury and the Sun, making it unsuitable for the habitable zone, where the presence of life is unlikely both now and in the future.
Currently in its “infancy,” TOI 1227 b is only 8 million years old, in contrast to Earth’s age of about 5 billion years, making it hundreds of times younger. It is the second youngest planet observed to undergo transits (passing in front of its parent star).
Researchers found that X-rays from the parent star are impacting TOI 1227 b, rapidly tearing apart its atmosphere, leading to a complete loss of atmosphere in about 1 billion years. By then, the planet’s mass will reduce to around twice that of Earth’s, whereas its current mass is about 17 times that of Earth’s.
Attila Varga, a doctoral student at the Rochester Institute of Technology leading the study, stated, “The atmosphere of this planet simply cannot withstand the large amount of X-rays it receives from its parent star.”
The parent star of TOI 1227 b, known as TOI 1227, has a mass only one-tenth that of the Sun. It appears dimmer and cooler in the visible light spectrum but brighter than the Sun in the X-ray spectrum. While the mass of TOI 1227 b is not certain, it may be similar to Neptune, with a diameter three times that of Neptune (similar to the size of Jupiter).
One of the authors of the study, Professor Joel Kastner, also from the Rochester Institute of Technology, believes that the planet’s structure is highly affected by continuous X-ray emissions from the parent star.
Alexander Binks, an associate professor at the University of Tübingen in Germany and another author of the report, expressed a pessimistic outlook for the future of TOI 1227 b, stating, “TOI 1227 b’s volume could shrink to about one-tenth of its current size, and its weight will decrease by more than 10%.”
Researchers used various data to estimate the age of TOI 1227 b, including measuring the motion of the parent star in space and comparing it with nearby stars of known age. They also compared the brightness and surface temperature of the parent star with theoretical models of stellar evolution.
Among all exoplanets discovered by astronomers with an age less than 50 million years, TOI 1227 b stands out for having the longest year and lowest mass.
The findings of this study have been published in The Astrophysical Journal.