The VLT (Very Large Telescope) of the European Southern Observatory (ESO) has taken the first image of a young Sun-like star accompanied by two giant exoplanets. Images of systems with multiple stars around them are extremely difficult to obtain and, until now, astronomers have never directly observed more than one planet orbiting a Sun-like star.
Just a few weeks ago, ESO revealed the birth of a planetary system through a stunning new image obtained by the VLT. Now, the same telescope has taken the first direct image of a planetary system around a star like the Sun, located about 300 light-years away and known as ‘TYC 8998-760-1’, using the same instrument.
“This discovery is a snapshot of an environment that is very similar to our solar system, but at a much earlier stage in its evolution,” says Alexander Bohn, a doctoral student at Leiden University, the Netherlands, who led the New research published this Wednesday in ‘The Astrophysical Journal Letters’. “Although astronomers have indirectly detected thousands of planets in our galaxy, only a small fraction of these exoplanets have been imaged directly,” explains co-author Matthew Kenworthy, an associate professor at Leiden University, adding: “The direct observations are important in the search for environments that can harbor life”. Furthermore, they can help astronomers understand how planets around the Sun formed and evolved.
The direct image of two or more exoplanets around the same star is even rarer; so far only two of these systems have been directly observed, both around very different stars from the Sun. “Our team has been able to capture the first image of two gas giant companions orbiting a young solar analogue,” says Maddalena Reggiani, researcher postdoctoral fellow from KU Leuven (Belgium) who has also participated in the study. ESO’s VLT was also the first telescope to obtain a direct image of an exoplanet, back in 2004, when it captured a speck of light around a brown dwarf, a type of “failed” star.
Heavier and farther from its star
The two planets can be seen in the new image as two bright spots of light away from their parent star, which is located in the upper left of the image. By taking different images at different times, the team was able to distinguish these planets from the background stars. Orbiting its star host at distances of 160 and 320 times the distance between Earth and the sun. The team also found that the two exoplanets are much heavier than those in the solar system, with the inner planet 14 times the mass of Jupiter and the outer planet 6 times more.
Bohn’s team obtained images of this system during their search for young, giant planets around stars like our Sun, but much younger. The star TYC 8998-760-1 is just 17 million years old and is found in the southern constellation Musca. Bohn describes it as a “very young version of our own Sun”.
While older planets, like those in the solar system, are too cold to be detected with this technique, young planets are hotter, and therefore shine more in the infrared range of light. Taking several images thanks to the high performance of the SPHERE instrument, installed in ESO’s VLT, last year in the Chilean Atacama desert and analyzing ancient data dating back to 2017, the research team revealed that the two planets are part of the star system.
In order for astronomers to confirm whether these planets formed at their current location, away from the star, or migrated from other places, more observations of this system will be needed, observations that can be carried out even with ESO’s future Extremely Large Telescope (ELT). ESO’s ELT will also help study the interaction between two young planets in the same system. “The possibility that future instruments, such as those that will be available in the ELT, will be able to detect even smaller mass planets around this star, marks an important milestone in understanding multi-planetary systems, with possible implications for the history of our own solar system,” Bohn concludes.