Astronomers have likely found what could turn out to be the youngest planet ever observed.
As announced in The Astrophysical Journal Letters today, the infant planet is barely 395 light-years from Earth and began forming only 1.5 million years ago. For comparison, Earth at 4.543 billion years is 3,000 times older than this infant planet and its parent star.
The planet found in the constellation Ophiuchus’s star-forming region is, in astronomical years, very much in its parent star’s cradle. Looking at the light, and therefore data which is only 395 years old, shows gas dust are still combining to form this planet. It is likely the youngest exoplanet, or a planet outside the home solar system, ever found among some 5,000 discovered so far.
A team of scientists used the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile to gather data about the baby planet. ALMA brings together 66 antennas all working together as one. ALMA was trained at a star named AS 209, which is a T Tauri star. Such stars are generally very young at only a few million years, still partially wrapped in the cloud of dust and gas.
According to the Encyclopedia Britannica, “T Tauri stars are characterized by erratic changes in brightness. They represent an early stage in stellar evolution, having only recently been formed by the rapid gravitational condensation of interstellar gas and dust. These young stars are relatively unstable, though contracting more slowly than before, and will remain in that condition until their interior temperatures become high enough to support thermonuclear reactions for energy generation. More than 500 T Tauri stars have so far been observed. The Sun is thought to have gone through the T Tauri stage in its early youth.”
The observation revealed that the circumstellar disk around AS 209 had many gaps, in one of which this baby planet was found. The AS 209 disk is approximately or equal to 140 astronomical unit or au in size and has multiple pronounced concentric rings and gaps. One au equals the average distance between the Sun and Earth of 92,955,807.3 miles.
With James Webb, the most sophisticated and powerful space telescope so far, already producing some breathtaking results, it is expected to be deployed to get clearer data about the baby planet.
The scientists say in their paper, “We infer that the planet’s mass is around a Jupiter mass. How did a giant planet form at an orbital radius of 200 au? One possibility is that the AS 209 disk was gravitationally unstable in the past and the planet formed via gravitational instability.”
“Observing planets at this young age allows us to place strong constraints on the mechanism and timescale of planet formation, crucial to gaining new insights into the formation and evolution of giant planets,” the paper says.
What is extraordinary about the baby planet is its distance from its parent star. It is 200 au away from the parent star which is about 19 billion miles. Compare that with Neptune, the outermost planet in our solar system, which is 2.8 billion miles from the Sun.
Studying this baby planet offers exciting opportunities to address some fundamental questions about the origin of not just planets and solar systems but eventually everything within the universe.