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Debate Continues over Whether Trappist Planet Has Atmosphere
An international team of astronomers suggests that, contrary to previous results, the rocky exoplanet Trappist-1b might be a bit more interesting that it appears.
An earlier analysis of data from the James Webb Space Telescope indicated that Trappist-1b is a bare, airless rock of a world. But thanks to additional observations, Elsa Ducrot (Observatory of Paris) and others now suggest that either the planet’s surface is indeed airless but recently resurfaced by geological processes (think volcanism and plate tectonics) or it has a thick, hazy atmosphere of carbon dioxide. The latter scenario is less likely, the team reports December 16th in Nature Astronomy.
Analyzing exoplanets’ atmospheres and compositions is an endeavor fraught with ambiguity, as we explain in our December issue. You can read more about the Trappist-1b result in the thorough press release from the Max Planck Institute for Astronomy.
Chemically Pristine Stars Keep Their Planet-forming Disks Longer
NASA / ESA / CSA / STScI / Olivia C. Jones (UK ATC) / Guido De Marchi (ESTEC) / Margaret Meixner (USRA)
Previous studies have found that gas giant planets are far more likely to form around stars with high levels of elements heavier than helium, called metals. But low-metallicity stars do occasionally have big planets — which is odd, because astronomers thought planet-forming disks around such stars wouldn’t last long enough to build a big world.
A new study by Guido De Marchi (European Space Research and Technology Centre, Noordwijk, The Netherlands) and others supports the idea that metal-poor disks last much longer than expected. The team pointed the James Webb Space Telescope at a star-forming cluster in the Small Magellanic Cloud and found disk-girthed stars that appear to be a few tens of millions of years old — a factor of 10 older than predicted.
The disks might last so long either because it takes longer for a star’s light to disperse the disk if there’s a low amount of heavy elements, or because stars forming in a low-metallicity gas cloud pack on more material before they collapse to become stars, the team suggests. The study appears in the December 16th Astrophysical Journal.