For the first time ever, astronomers have directly imaged multiple planets orbiting a sun-like star.
The European Southern Observatory’s Very Large Telescope (VLT) in Chile photographed two giant planets circling a very young analogue of our own sun that lies about 300 light-years from Earth, a new study reports.
“This discovery is a snapshot of an environment that is very similar to our solar system, but at a much earlier stage of its evolution,” study lead author Alexander Bohn, a doctoral student at Leiden University in the Netherlands, said in a statement.
The study was published online Wednesday in The Astrophysical Journal Letters.
Before this historic cosmic portrait, only two multi-planet systems had ever been directly imaged, and neither of them features a sunlike star, study team members said. And snapping a photo of even a single exoplanet remains a rare achievement.
“Even though astronomers have indirectly detected thousands of planets in our galaxy, only a tiny fraction of these exoplanets have been directly imaged,” study co-author Matthew Kenworthy, an associate professor at Leiden University, said in the same statement.
Bohn, Kenworthy and their colleagues studied the 17-million-year-old star with the VLT’s Spectro-Polarimetric High-contrast Exoplanet Research instrument, or SPHERE for short. SPHERE uses a device called a coronagraph to block a star’s blinding light, allowing astronomers to see and study orbiting planets that would otherwise be lost in the glare.
The newly reported SPHERE imagery revealed two planets in the system. Astronomers already knew about one — a team led by Bohn announced its discovery late last year — but the other is a newfound world.
The two planets are huge and farflung. One of the planets is about 14 times more massive than Jupiter and orbits at an average distance of 160 astronomical units (AU), and the smaller planet is six times heftier than Jupiter and lies about 320 AU from the host star. One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers. For comparison: Jupiter and Saturn orbit our sun at just 5 AU and 10 AU, respectively.
It’s unclear whether the two planets formed at their present locations or were pushed out there somehow. Further observations, including those made by huge future observatories such as the European Extremely Large Telescope (ELT), could help to solve that mystery, study team members said.
Other questions remain about the system. For example, do the two gas giants have company? Might several rocky planets circle relatively close to the star, as they do in our solar system?
“The possibility that future instruments, such as those available on the ELT, will be able to detect even lower-mass planets around this star marks an important milestone in understanding multiplanet systems, with potential implications for the history of our own solar system,” Bohn said.