Astronomers discover 2 planets orbiting a Sun-like star, could hold clues for environments that support life
This is the first direct image of more than one exoplanet around a star similar to the Sun, say researchers
Astronomers have captured what they are describing as the first-ever image of a young, Sun-like star accompanied by two giant exoplanets. Images of systems with multiple exoplanets are extremely rare, and until now scientists had never directly observed more than one planet orbiting a star similar to the Sun, says the research team. The observations can help astronomers understand how planets formed and evolved around our own Sun, they explain.
The two gas giants -- TYC 8998-760-1b and TYC 8998-760-1c -- orbit their host star TYC 8998-760-1 at distances of 160 and about 320 times the Earth-Sun distance. This places these planets much further away from their star than Jupiter or Saturn (also two gas giants) are from the Sun. They lie at only 5 and 10 times the Earth-Sun distance, respectively. The team also found the two exoplanets are much heavier than the ones in our Solar System, the inner planet having 14 times Jupiter's mass and the outer one six times.
The image was taken by the European Southern Observatory's Very Large Telescope (ESO's VLT). “A few weeks ago, ESO revealed a planetary system being born in a new VLT image. The same telescope, using the same instrument, has taken the first direct image of a multi-planet system around a star like our Sun, located about 300 light-years away and known as TYC 8998-760-1,” say researchers in their findings published in The Astrophysical Journal Letters.
“The discovery is a snapshot of an environment that is very similar to our solar system, but at a much earlier stage of its evolution,” writes Alexander Bohn, a PhD student at Leiden University, the Netherlands, who led the new research. Bohn’s team imaged this system during their search for young, giant planets around stars like the Sun but far younger. The star TYC 8998-760-1 is just 17 million years old and located in the Southern constellation of Musca (The Fly). Bohn describes it as a “very young version of our own Sun.”
The research team also includes experts from the University of Amsterdam, the Netherlands; the University of Exeter, UK; California Institute of Technology, US; University of Rochester, US; Rockhurst University, US; and KU Leuven, Belgium.
While astronomers have indirectly detected thousands of planets in the Milky Way galaxy, only a tiny fraction of these exoplanets have been directly imaged, says co-author Matthew Kenworthy, an associate professor at Leiden University. The direct imaging of two or more exoplanets around the same star is even rarer; only two such systems have been directly observed so far, both around stars markedly different from the Sun, according to scientists. “Direct observations are important in the search for environments that can support life,” says Kenworthy.
The images were possible due to the “high performance” of the SPHERE instrument on ESO's VLT in the Chilean Atacama desert. SPHERE blocks the bright light from the star using a device called a coronagraph, allowing the much fainter planets to be seen. While older planets, such as those in the solar system are too cool to be found with this technique, young planets are hotter, and so glow brighter in infrared light. By taking several images over the past year, as well as using older data going back to 2017, the research team confirmed that the two planets are part of the star's system.
According to the authors, further observations of this system, including with the future ESO Extremely Large Telescope (ELT), will enable astronomers to test whether these planets formed at their current location distant from the star or migrated from elsewhere. ESO's ELT will also help probe the interaction between two young planets in the same 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 multi-planet systems, with potential implications for the history of our solar system,” says Bohn.