Exoplanets come in many different types and sizes, and in order to understand how planets form and evolve, it is helpful to observe them at different points in their life cycle. NASA’s TESS exoplanet hunting satellite recently discovered four “teenage” exoplanets, including a dramatic lava world orbiting extremely close to its star.
TESS examined two young stars that are close to each other and are believed to be related, TOI 2076 and TOI 1807. They found four exoplanets in their orbits that are in a rarely observed middle phase between youngest birth and maturity.
“The planets in both systems are in a transition or teenage phase of their life cycle,” said Christina Hedges, an astronomer at the Bay Area Environmental Research Institute in Moffett Field and NASA’s Ames Research Center in Silicon Valley. “They are not newborns, but neither are they sedentary. Learning more about planets in this youth phase will ultimately help us understand older planets in other systems. “
Three of the exoplanets orbit TOI 2076, each of which is referred to as mini-Neptune because they are large between Earth and Neptune.
But the really dramatic planet is the one orbiting TOI in 1807. The planet TOI 1807 b is so close to its star that a year there only lasts 13 hours. This planet is the latest version of such a planet, known as the ultra-short-term planet, which has been discovered so far. If the planet is mostly rock and doesn’t have a thick atmosphere, researchers predict that it could be covered in lakes or even oceans of lava.
Planets with short periods or with orbits less than a day are rare. The potential lava world TOI 1807 b shown here is the youngest specimen discovered so far. NASA Goddard Space Flight Center / Chris Smith (KBRwyle)
This planet is also bombarded with UV radiation because its star is so young and active. It is estimated that the planet is hit by 22,000 times the amount of UV radiation from its star than Earth is hit by the sun. And the other star is also similarly active.
“The stars produce maybe ten times more UV light than they will when they reach the age of the Sun,” says co-author George Zhou, an astrophysicist at the University of Southern Queensland in Australia. “Since the sun may have been just as active at one time, these two systems could give us a glimpse into the early states of the solar system.”