Among the most eagerly awaited results from the early observations of the James Webb Space Telescope (JWST) is whether or not the seven rocky planets of the TRAPPIST-1 system have atmospheres.
The TRAPPIST-1 planets are close to us (40 light-years away), are all solid rather than gaseous, and they orbit a cool and small sun that makes the planets easier to observe and measure. Not surprisingly, all seven of the planets in the system will be observed during the first year of JWST observations and the results have begun to come in.
And so far, at least, the planets do not have atmospheres, or at least don’t have substantial atmospheres.
The planet closest to its sun, TRAPPIST 1-b was determined to be devoid of an atmosphere earlier this year and last week a Nature paper reportsed that TRAPPIST 1-C also does not appear to have anything more than a very thin atmosphere.
Neither findings was completely surprising, since these are the two planets closest to the star. But even so, the results indicate that gaseous atmospheres require a particular collection of planetary, stellar and system conditions that may be difficult to achieve.
“TRAPPIST-1 c is interesting because it’s basically a Venus twin,” explained co-author Laura Kreidberg, co-author of the paper and and Director at Max Planck Institute for Astronomy in Germany. “It’s about the same size as Venus and receives a similar amount of radiation from its host star as Venus gets from the Sun.”
Before the observations, she said “we thought it could have a thick carbon dioxide atmosphere like Venus.” But now, “we can definitely rule out a thick and Venus-like atmosphere.”
In a Max Planck Institute release, the large international team studying TRAPPIST 1-C reports that while faint signals of a possible thin atmosphere were detected, that data did not come from a detection of atmospheric chemicals. A barren rock with a surface layer of material weathered from stellar irradiation, it reported, could explain the observations equally well as a thin atmosphere would.… Read more