Astronomers spot possible third planet around closest star to our sun
Finding the featherweight world boosts the odds of finding livable worlds like our own elsewhere in the galaxy.
- Finalist for the Nesta Tipping Point prize and a degree in broadcast journalism from the University of Missouri-Columbia.
This artist's impression shows a close-up view of Proxima d, a planet candidate recently found orbiting the red dwarf star Proxima Centauri, the closest star to the solar system.
The closer we look at the universe, the more crowded it seems to be, at least in terms of exoplanets.
It's only been about three decades since humans detected a planet around a star for the first time. Since then we've cataloged thousands of them throughout the galaxy (and maybe even some beyond the Milky Way), including a growing solar system around our nearby cosmic neighbor, Proxima Centauri.
A team using the European Southern Observatory's Very Large Telescope in Chile says they've discovered a new planet candidate orbiting very close in around the M dwarf star located just 4 light-years from Earth.
"The discovery shows that our closest stellar neighbor seems to be packed with interesting new worlds, within reach of further study and future exploration," said João Faria, from Portugal's Instituto de Astrofísica e Ciências do Espaço, in a statement.
Faria is also lead author on a paper outlining the find that was published Thursday in the journal Astronomy & Astrophysics.
The potential new world, named Proxima d, has yet to be fully confirmed and is considered a planet candidate at the moment. It appears to be one of the lightest exoplanets ever found, at just one-third the mass of our own planet.
It orbits 10 times closer to Proxima Centauri than Mercury does to our sun, completing an orbit around the red star in only five days. This makes the prospects for life on Proxima d very dim as it doesn't orbit in the habitable zone where liquid water could exist. Proxima Centauri is also thought to be a very active star that regularly blasts flares of sterilizing radiation out toward its planets.
Right now those other planets include Proxima b, which has a similar mass to Earth's and does orbit in the habitable zone, and Proxima c, a cold world orbiting much farther out.
The first signs of a world orbiting very close to Proxima Centauri actually came in 2020 when the Very Large Telescope, aka VLT, was used to confirm the existence of Proxima b. But the signal was faint, so follow-up observations had to be done.
"After obtaining new observations, we were able to confirm this signal as a new planet candidate," Faria explained. "I was excited by the challenge of detecting such a small signal and, by doing so, discovering an exoplanet so close to Earth."
While there's little hope that the newfound planet is habitable, the discovery should help pave the way to discovering more extremely lightweight planets that have been missed in the past.
"This achievement is extremely important," says ESO's Pedro Figueira, who works with the VLT instrument that found Proxima d. He says the find shows "the potential to unveil a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that can potentially host life as we know it."
