Astrobiology.com's October 9 list brings together several separate astronomy developments rather than one new study. The biggest numerical milestone comes from NASA's planet-hunting TESS mission, while the other items range from changing water clouds on a nearby brown dwarf to an unusual molecule around a young star and a possible planet formed after its star died.
TESS crosses 1,000 confirmed planets
Scientists have now confirmed 1,000 exoplanets using data from NASA's Transiting Exoplanet Survey Satellite. According to Caltech's IPAC, a batch of 70 newly confirmed worlds pushed TESS across the threshold and raised the NASA Exoplanet Archive's overall count to 6,445 confirmed planets.
TESS launched in 2018 to search for the small, periodic dips in starlight caused when planets pass in front of their stars. Its tally is likely to keep rising: the archive still lists 4,823 TESS Project Candidates awaiting confirmation, while more than 8,000 candidates have been uploaded to the Exoplanet Follow-up Observing Program.
A nearby brown dwarf has changing water clouds
The James Webb Space Telescope has delivered the first direct confirmation that water-cloud thickness changes over time on an object beyond our solar system. The target, WISE 0855, is a Jupiter-sized brown dwarf about 7.5 light-years away. Brown dwarfs are not planets, but they are cool enough to serve as useful laboratories for weather on giant, planet-like worlds.
Researchers used Webb to observe WISE 0855 for 11 hours, collecting a spectrum every 15 minutes. The University of Arizona team reported that two processes drive its changing appearance: high-altitude water-ice clouds become thicker and thinner as the object rotates, while deeper gases also change the light emerging from its atmosphere. The finding gives astronomers a nearby test case for interpreting weather on gas-giant exoplanets.
Heavy methanol exposes a gap in chemistry models
Astronomers have also detected fully deuterated methanol, CD3OD, in space for the first time. In this rare form of methanol, every hydrogen atom has been replaced with deuterium, a heavier isotope of hydrogen.
The molecule was found around the protostar IRAS4A2 in the Perseus molecular cloud, about 1,000 light-years from Earth. The Max Planck Institute for Radio Astronomy describes it as both the first detection of CD3OD in space and the first known quadruply deuterated interstellar molecule.
