“It’s increasingly seeming that the solar system is something of an oddball,” said Gregory Laughlin, a planetary scientist at the University of California, Santa Cruz. “While it’s still too soon to know for sure how odd the solar system is, if it turns out to be a cosmological anomaly, then so might be Earth – and life.”
ESO’s VLT Captures a “Very Young Version of our Own Sun”
“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,” says Alexander Bohn, at Leiden University in the Netherlands, about the image of a young, Sun-like star with multiple planets directly imaged located about 300 light-years away in the Southern constellation of Musca (The Fly) in July of 2020 by the European Southern Observatory’s Very Large Telescope (ESO’s VLT). Bohn’s team imaged this system during their search for young, giant planets around stars like our Sun but far younger. The star TYC 8998-760-1 is just 17 million years old. Bohn describes it as a “very young version of our own Sun”.
The star, TYC 8998-760-1 is accompanied by two giant exoplanets . Images of systems with multiple exoplanets are extremely rare. Astronomers had never directly observed more than one planet orbiting a star similar to the Sun.
First Direct Image of More than One Exoplanet around a Sun-like Star
“Even though astronomers have indirectly detected thousands of planets in our galaxy, only a tiny fraction of these exoplanets have been directly imaged,” said co-author Matthew Kenworthy, Associate Professor at Leiden University, adding that “direct observations are important in the search for environments that can support life.” This new ESO VLT image is the first direct image of more than one exoplanet around a Sun-like star. ESO’s VLT was also the first telescope to directly image an exoplanet, back in 2004, when it captured a speck of light around a brown dwarf, an object too small to be a star but too big to be a planet.
Mysterious World of a Brown Dwarf?
“Brown dwarfs are mysterious worlds,” reports NASA, “with many unanswered questions about their properties and appearance. They’re too massive to be planets, but not quite massive enough to be stars. TYC 8998-760-1 b is immense, about 14 times the mass, or heft, of our own planet Jupiter, and likely three times as big. The estimated temperature at its surface is about 2,600 degrees Fahrenheit (1,400 degrees Celsius). This object’s extreme girth is unusual for brown dwarfs, and could indicate that its youthful atmosphere is highly inflated. Another possibility, which can’t yet be ruled out, is that it’s really two objects orbiting each other, these in turn orbiting the star.”
The ESO Image
“Our team has now been able to take the first image of two gas giant companions that are orbiting a young, solar analogue,” said Maddalena Reggiani, a postdoctoral researcher from KU Leuven, Belgium, who participated in the study. The two planets can be seen in the new image below as two bright points of light distant from their parent star, which is located in the upper left of the frame. By taking different images at different times, the team were able to distinguish these planets from the background stars.
The Two Gas Giants are Much Further Away from Their Star than Jupiter or Saturn
The two gas giants orbit their host star 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, reports the ESO. 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.
Planets Confirmed by ESO’s Sphere
These images were possible thanks to the high performance of the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) 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 our 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 an extended time baseline, including data going back to 2017, the research team have confirmed that the two planets are part of the star’s system.
Further observations of this system, including with the future European Extremely Large Telescope (ELT) –a revolutionary scientific project for a 30m-class telescope that will address the most pressing unsolved questions about our Universe–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 own Solar System,” concluded Bohn.
Source: “Two Directly Imaged, Wide-orbit Giant Planets around the Young, Solar Analog TYC 8998-760-1” to appear in The Astrophysical Journal Letters (https://doi.org/10.3847/2041-8213/aba27e).
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