Located just 25 light-years away from Earth, what surrounds the star Vega could disrupt our understanding of how extraterrestrial worlds form.
The James Webb Space Telescope has captured a strangely smooth cosmic debris disk around Vega, a bright blue supergiant star, the brightest in the Lyra constellation.
This is a massive protoplanetary disk, akin to the protoplanetary disk of the early Solar System, where Earth and other planets were born.
However, the protoplanetary disk surrounding Vega exhibits characteristics that scientists describe as “inexplicable.”
The protoplanetary disk around Vega is remarkably smooth – (Graphic: UNIVERSITY OF ARIZONA).
A research team from the Steward Observatory at the Lunar and Planetary Science Institute of the University of Arizona, the Space Science Institute, NASA’s Jet Propulsion Laboratory (USA), and Trinity College Dublin (Ireland) studied this peculiar structure.
Protoplanetary disks are expected to have gaps where gas and dust coalesce to form planets.
However, according to Dr. Andras Gáspár from the University of Arizona, the disk around Vega is unusually smooth, indicating that no planets exist around it.
There is a faint gap about 60 astronomical units (AU, where 1 AU is the distance from the Earth to the Sun) from the star.
However, upon closer examination, this is merely the result of a small amount of dust being blown farther away by radiation, rather than due to a forming planet.
Vega is younger than the Sun—approximately 455 million years old—but is old enough to have birthed planets. For comparison, Earth is estimated to be less than 10 million years younger than the Sun.
When comparing Vega to Fomalhaut, a slightly younger star, the absurdity of its smooth disk becomes even more apparent.
Fomalhaut is a perfect counterpart to Vega, also a bright blue-white star, with a large gap in its protoplanetary disk indicating the presence of a giant planet or several smaller planets that have formed.
Researchers cannot explain why Vega cannot produce exoplanets while Fomalhaut seemingly can, despite the similar physical mechanisms believed to exist in both star systems.
The researchers proposed several scenarios, but none explain why Vega is unable to form planets.
They also wonder whether many similarly unformed, smooth protoplanetary disks can be found throughout the universe.
If they are indeed common, the calculations regarding the number of planets that could exist in the galaxy or the universe could be profoundly affected.
“This makes us rethink the scope and diversity among exoplanet systems,” concluded Dr. Kate Su from the University of Arizona.
