For anybody interested, attached is a spreadsheet with all JWST observatons to date of the TRAPPIST-1 planets, plus another observation planned to take place on November 12, 2022
Updated list of Trappist-1 observations with JWST, with added program titles.
https://twitter.com/nasawebb/status/1640370455675559936TRAPPIST-1 b: We give it a one (M-dwarf) star review; it lacks atmosphere. ⭐
Webb found the dayside temperature of this rocky exoplanet to be about 450º F (227º C) — suggesting it has no significant atmosphere: https://www.nasa.gov/feature/goddard/2023/nasa-s-webb-measures-the-temperature-of-a-rocky-exoplanet
Here’s why this is a big deal ⬇️
First, a refresher: TRAPPIST-1 b is the innermost of 7 rocky planets (found in 2017) orbiting the M dwarf star TRAPPIST-1. M dwarf stars are intriguing because they are 10 times as common and 2 times more likely to have rocky planets than stars like our Sun.
Scientists made models for TRAPPIST-1 b: with an atmosphere, and without. Webb’s results matched the model with no atmosphere. If TRAPPIST-1 b did have an atmosphere to circulate and distribute heat, its temperature should have been much cooler than what was measured.
How do you take a planet’s temperature? The team measured the change in brightness (in infrared light, or emitted heat energy) when TRAPPIST-1 b moved behind its star. This was a challenge because the star is 1000 times brighter, and the change in brightness was less than 0.1%.
No previous telescope has had the sensitivity to measure such dim mid-infrared light. This is the first detection of any form of light emitted by a rocky planet as small & cool as those in our solar system. It bodes well for Webb's ability to study temperate, Earth-sized planets!
Studying TRAPPIST-1 b gives us clues about its 3 siblings in the habitable zone (where conditions could support liquid water on their surfaces) & other M-dwarf systems. It's a key step to figuring out if planets around M-dwarf stars can sustain atmospheres needed to support life.
Captions for attached graphics:
Modified version of a previous, popular artist illustration of the TRAPPIST-1 star system. The background is black. At the top there is a “TRAPPIST-1 System” label in bold white text. At far left is a representation of the TRAPPIST-1 star, an M class dwarf star. It is seen as a glowing orange-yellow semi-circle. To the right of the star, illustrations of its planets are shown in a line. There are seven, with slight variations in sizes. They are labeled b, c, d, e, f, g and h, with b being closest to the star. They all resemble mottled clay marbles in browns and dark greens. The planet TRAPPIST-1 b has been spotlighted to stand out. The other planets are dimmed down to be less visible. The planet b also has a white label as opposed to gray letter labels for the rest of the planets. At bottom right is the word “Illustration (2018)” in tiny gray text.
Infographic titled, “Rocky Exoplanet TRAPPIST-1 b Dayside Temperature Comparison, MIRI F1500W” showing five planets plotted along a horizontal temperature scale: Earth, TRAPPIST-1 b, Mercury, and two different models of TRAPPIST-1 b. The temperature scale is labeled in kelvins and degrees Fahrenheit, and ranges from 0 kelvins (negative 459 degrees Fahrenheit) at the left to 800 kelvins (980 degrees Fahrenheit at the right). The planets are plotted along the temperature scale at the following temperatures: Earth Measured at 290 kelvins (60 degrees Fahrenheit); TRAPPIST-1 b Measured at about 500 kelvins and 445 degrees Fahrenheit; “Mercury Measured” at 700 kelvins (800 degrees Fahrenheit). TRAPPIST-1 b Model with atmosphere is plotted at 400 kelvins (260 degrees Fahrenheit); TRAPPIST-1 b Model with no atmosphere is plotted at about 510 kelvins and 455 degrees Fahrenheit. TRAPPIST-1 b Measured is plotted at almost the same temperature as TRAPPIST-1 b Model with no atmosphere.
Infographic titled “Rocky Exoplanet TRAPPIST-1 b Secondary Eclipse Light Curve, MIRI Time-Series Photometry (F1500W).” At the top of the infographic is a diagram showing a planet moving behind its star (a secondary eclipse). Below the diagram is a graph showing the change in brightness of 15-micron light emitted by the star-planet system over the course of 3.5 hours. The diagram and graph are aligned vertically to show the relationship between the geometry of the star-planet system as the planet orbits, and the measurements on the graph. The infographic shows that the brightness of the system decreases markedly as the planet moves behind the star.
Some recent papers on TRAPPIST-1
TRAPPIST-1 and its compact system of temperate rocky planets
M. Gillon, Jan 2024
https://arxiv.org/pdf/2401.11815.pdfA roadmap to the efficient and robust characterization of temperate terrestrial planet atmospheres with JWST, Oct 2023
https://arxiv.org/pdf/2310.15895.pdfJust my interpretation but it looks like these two together say that the initial observations on planets b and c of TRAPPIST-1 point towards more rocky, air-less worlds and that even with JWST getting better info is tricky and requires time. Which is why the "roadmap" paper already wants to change the observation schedule to have a chance for better results in less time than currently planned. In any case, I like the Gillon paper as interesting summary of "where are we now?". Especially page 9 and later. We will see what comes up with more observations. I would hope for a Venus like world but looks unlikely so far.