Astronomers have discovered strong evidence for the existence of a massive natural satellite outside our solar system, using the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile.
If confirmed, the discovery could mark the first confirmed detection of an exosatellite—a celestial body orbiting another star outside our solar system—according to Science Daily.
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However, the object detected in the CD-35 2722 star system does not resemble any known moon. It has a mass comparable to that of Jupiter and does not orbit a planet, but rather a brown dwarf— a celestial body with a mass greater than that of planets but insufficient to sustain the nuclear fusion reactions that characterize stars. The astronomers’ findings were presented in a study published in the scientific journal *Nature*.
An Unusual Stellar System
At the center of the relatively young system CD-35 2722 lies a star with about half the mass of the Sun. Orbiting it is a brown dwarf with a mass more than 30 times that of Jupiter. The putative satellite, in turn, orbits the brown dwarf, forming an unusual triple system.
“This system is somewhat difficult to define using terms from our solar system such as ‘planet’ and ‘moon,’” notes lead researcher Kevin Hoy, an ESO researcher in Chile.
According to the study, the potential satellite has a minimum estimated mass of about 0.9 times that of Jupiter and completes one orbit around the brown dwarf in about 170 days. Its size poses an interesting classification problem. Its mass is large enough to be considered a planet, but it does not orbit a star directly.
“The fact that it is the third body in this system makes us want to call it a moon, even though it bears no resemblance to the small, rocky satellites of our solar system,” explains Hoy.
How it was discovered
The scientists used the VLT’s CRIRES+ instrument, applying the radial velocity method, which had also been used to discover the first exoplanet orbiting a Sun-like star.
The method relies on detecting microscopic variations in the motion of a celestial body, caused by the gravitational pull of a smaller companion. In this case, astronomers detected periodic variations in the brown dwarf’s motion, suggesting the presence of a possible satellite.
Although more than 6,000 exoplanets have been discovered, no exomoon has been confirmed with certainty to date. Scientists estimate that future observations, particularly with ESO’s new Extremely Large Telescope (ELT), featuring a 39-meter-diameter mirror, will allow for the detection of even smaller moons.
Source: CNN.gr
