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If confirmed, it would be the first moon-like object ever found beyond our Solar System.<\/p>\n
A system that refuses to fit the rules<\/p>\n
The system, known as CD-35 2722, is young and unlike anything in our Solar System. At its center is a star with about half the Sun\u2019s mass.<\/p>\n
Orbiting that star is a brown dwarf<\/a>, an object too massive to be considered a planet but not massive enough to sustain the nuclear fusion that powers true stars.<\/p>\n The newly detected object circles the brown dwarf instead of the star. It is at least as massive as Jupiter<\/a>, while the brown dwarf is more than 30 times Jupiter\u2019s mass. <\/p>\n That unusual setup has left astronomers debating what to call it.<\/p>\n After studying the system for months, Kevin Hoy, an ESO<\/a> student in Chile and lead author of the study, described it as \u201csuper weird\u201d compared to our own.<\/p>\n A moon that might also be a planet<\/p>\n Scientists currently refer to the object as an exosatellite, meaning a natural satellite outside our Solar System<\/a>. <\/p>\n The term exomoon is also commonly used for natural satellites beyond our planetary neighborhood, although there is no official definition that covers unusual systems like this one.<\/p>\n \u201cThis system is somewhat hard to define using Solar-System-based words like \u2018planet<\/a>\u2019 and \u2018moon\u2019,\u201d noted Hoy, who is also affiliated with the Universidad Diego Portales and the Millennium Nucleus of Young Exoplanets and their Moons (YEMS<\/a>) in Chile.<\/p>\n \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.\u201d<\/p>\n \u201cBeing the third wheel in this system makes us want to call it a moon<\/a>, even if it is nothing like the small, rocky moons we have in our system.\u201d<\/p>\n Why brown dwarfs complicate things<\/p>\n Brown dwarfs occupy one of astronomy\u2019s gray areas. They form much like stars but never gather enough mass to ignite long-lasting hydrogen fusion in their cores. <\/p>\n Because of that, brown dwarfs blur the line between stars and giant planets.<\/p>\n Alice Zurlo, YEMS Director and collaborator on the study, explained why that matters. <\/p>\n \u201cThe satellite we report is a giant gaseous body orbiting a highly massive companion, itself several times the mass of Jupiter,\u201d said Zurlo.<\/p>\n \u201cWe have a clear delineation between the planets and the Sun in the Solar System, so defining things like moons is simple.\u201d<\/p>\n \u201cIn the CD-35 2722 system, where we are blurring the lines between stars<\/a>, planets, and moons, the whole thing becomes more complicated to describe.\u201d<\/p>\n A long search may finally pay off<\/p>\n Astronomers have discovered more than 6,000 exoplanets over the past few decades. Finding moons around those distant worlds has been much harder. <\/p>\n Only a handful of possible exomoons have been reported so far, and none has been confirmed with strong enough evidence to settle the question.<\/p>\n Just a few months ago, another research team led by Quentin Kral found hints of a satellite in the HD 206893 star system using the European Southern Observatory\u2019s Very Large Telescope Interferometer. <\/p>\n Those observations suggested a possible companion but stopped short of a firm detection. The new observations may change that.<\/p>\n Detecting an invisible companion<\/p>\n The research team used the CRIRES+ instrument on the European Southern Observatory\u2019s Very Large Telescope. <\/p>\n They relied on the radial velocity method, the same technique that led to the discovery of the first exoplanet orbiting a Sun-like star.<\/p>\n Instead of looking directly at the suspected satellite, the researchers measured tiny back-and-forth movements in the brown dwarf. <\/p>\n Those small wobbles revealed the gravitational pull of an unseen object moving around it.<\/p>\n \u201cThis system is truly unique and represents a breakthrough: the first plausible detection of an exosatellite,\u201d said Zurlo.<\/p>\n More moon-like worlds may be waiting<\/p>\n This evidence, while needing confirmation, is indicative of a time in which astronomers might discover an abundance of such peculiar systems.<\/p>\n Each such discovery allows scientists to understand better the development and evolution of planets, brown dwarfs, and their satellites.<\/p>\n With the launch of the European Southern Observatory\u2019s Extremely Large Telescope and its huge 128-foot mirror and innovative equipment, the detection of even smaller exomoons will be possible.<\/p>\n As more of these distant worlds come into view, astronomers may have to rethink the labels that have guided planetary science for generations.<\/p>\n The full study was published in the journal Nature<\/a>.<\/p>\n Image Credit: ESO\/ M. Kornmesser<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Scientists may have found the first moon beyond our Solar System. 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