Observations made with the European Southern Observatory\u2019s Very Large Telescope (ESO\u2019s VLT) have revealed evidence for a moon-like object in the CD-35 2722 system. Unlike moons in our Solar System, the newly found object does not orbit a planet, raising questions about what to name it. Instead, it circles a brown dwarf, an object larger than a planet, that orbits the CD-35 2722 star. If confirmed, this could be the first \u2018moon\u2019 discovered outside our Solar System.<\/p>\n\n\n\n
Kevin Hoy, an ESO student in Chile and lead author of the study published today in Nature<\/em>, describes the system he spent months analysing as \u201csuper weird<\/em>\u201d compared to our own. The biggest and most massive object in this young system is the star CD-35 2722, which has about half the mass of the Sun. The star is being orbited by a brown dwarf, an object too massive to be a planet but too small to be a star. The newly discovered object orbits this brown dwarf.<\/p>\n\n\n\n
\u201cThis system is somewhat hard to define using Solar-System-based words like \u2018planet\u2019 and \u2018moon\u2019<\/em>,\u201d states Hoy, who is also affiliated with the Universidad Diego Portales and the Millennium Nucleus of Young Exoplanets and their Moons (YEMS) in Chile. The new object, which the team call an exosatellite, is at least as massive as Jupiter while the brown dwarf has more than 30 times the mass of Jupiter. \u201cThe exosatellite is clearly massive enough to be a planet, but it does not orbit a star, though it orbits an object that orbits a star,”<\/em> says Hoy. “Being the third wheel in this system makes us want to call it a moon, even if it is nothing like the small, rocky moons we have in our system<\/em>.\u201d<\/p>\n\n\n\n
This exosatellite or \u2018exomoon\u2019, a natural satellite outside our Solar System [1], is difficult to label, given the differences in this system compared to our own. Alice Zurlo, YEMS Director and collaborator on the study explains: \u201cThe satellite we report is a giant gaseous body orbiting a highly massive companion, itself several times the mass of Jupiter<\/em>.\u201d<\/p>\n\n\n\n
\u201cWe have a clear delineation between the planets and the Sun in the Solar System, so defining things like moons is simple. In the CD-35 2722 system, where we are blurring the lines between stars, planets, and moons, the whole thing becomes more complicated to describe<\/em>,\u201d adds Zurlo, who is also an astrophysicist at Universidad Diego Portales.<\/p>\n\n\n\n