This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The James Webb Space Telescope (JWST) has opened many wonders of the cosmos to scientists since it began science operations a few years ago. But one thing it hasn't done is find an "exomoon." These still-theoretical moons orbit exoplanets in other star systems, and JWST was supposed to find a plethora of them.
However, it has found precisely none. The cause appears to be noise in the telescope's instrumentation or from the star itself. But a new paper, available in preprint form on arXiv, from David Kipping, an astronomer at Columbia and host of the Cool Worlds YouTube channel, shows how JWST can find an exomoon.
It likely just has to look for one in the same place repeatedly. Kipping analyzed data JWST collected on a planet called LP 890-9 c. This exoplanet orbits an ultracool red dwarf located around 105 light-years away.
With an 8.46-day orbital period, saying the planet is close to its star is an understatement, but, at least in theory, it is in the habitable zone of this extremely low-temperature host star. Another advantage was how often and how long JWST observed it—Kipping was able to analyze data from 12 different transits. Previous efforts to detect exomoons relied on a single transit.
For example, JWST watched the gas giant Kepler-167 e, hoping to spot a small moon in orbit around it. But "red noise" confused the computer models analyzing the data, making it impossible to detect any moon much smaller than Earth. "Red noise" is caused by slow, wandering changes in the detector, such as when it is warming up, its pointing drifts slightly or sunspots appear on the surface of the star itself.
The key, according to Kipping, is averaging. Exomoons have to obey the laws of physics, so they have to be in a certain place at a certain time around the planet. They don't simply pop up where an instrumental glitch happened.
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