Astronomers find one moving infrared candidate in the Planet Nine search
Researchers comparing infrared sky surveys from 1983 and 2006–07 identified one faint source whose slow movement could fit a distant planet, ZME Science reports. The team stresses it is only a candidate: two observations decades apart cannot establish an orbit, and a later sighting is needed to test whether it is Planet Nine.
Bottom line — A further observation with Chile’s Blanco Telescope could show whether the candidate keeps moving on a planetary orbit.
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The team compared data from IRAS and Japan’s AKARI spacecraft, whose surveys were separated by 23 years, according to ZME Science.
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After filtering more than a million sources from each survey, researchers narrowed the search to one candidate, ZME Science reports.
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The source shifted 47.46 arcminutes—about one and a half times the apparent width of the full Moon—between observations, according to ZME Science.
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The candidate’s brightness and motion fit the team’s search assumptions: a planet 500–700 astronomical units from the Sun and about 7–17 times Earth’s mass, ZME Science reports.
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One AKARI infrared measurement may be unreliable, and the search could miss a planet that is colder, smaller or farther away, the researchers caution, according to ZME Science.
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ScienceDaily notes that the newly discovered sednoid 2023 KQ14 has a stable orbit, challenging some Planet Nine scenarios; it says any such planet may need to be more than 500 astronomical units away.