Astronomers may have detected an exomoon - Boing Boing

What the report says

Boing Boing reports that astronomers using the European Southern Observatory’s Very Large Telescope in Chile have identified evidence for a moon-like object in the CD-35 2722 system, a finding that could become one of the strongest candidates yet for an exomoon. ESO announced the detection on July 22 alongside a Nature paper led by Kevin Hoy, an ESO student based in Santiago.

The system is unusual: the central star is described as roughly half the mass of the Sun, with a brown dwarf companion more than 30 times Jupiter’s mass. The newly reported body appears to orbit that brown dwarf and is itself at least as massive as Jupiter. Because it is a giant gaseous object circling a massive companion that is not a normal planet, researchers are treating the label “exomoon” cautiously.

Boing Boing notes that Hoy and co-author Alice Zurlo of Universidad Diego Portales used the CRIRES+ spectrograph to detect small shifts in the brown dwarf’s motion, a radial-velocity approach similar in principle to methods used to discover exoplanets. The article emphasizes that the terminology is unsettled: ESO says there is no formally accepted definition of an exomoon, and this object does not resemble familiar Solar System moons.

The possible detection matters because, while more than 6,000 exoplanets have been confirmed, confirmed moons beyond the Solar System remain elusive. The report also places the result in the context of earlier tentative exomoon claims and notes that future instruments, including ESO’s Extremely Large Telescope under construction in Chile, may provide sharper evidence and potentially detect smaller satellite-like bodies.