JWST-TST High Contrast: Living on the Wedge, or, NIRCam Bar Coronagraphy Reveals CO2 in the HR 8799 and 51 Eri Exoplanets' Atmospheres - publication
2025-03-17
Astronomers have announced that the James Webb Space Telescope (JWST) has successfully captured its first direct images of carbon dioxide gas on a planet beyond the solar system, the findings are both a testament to the telescope’s power in direct imaging and provide valuable insights into how planets form, both within our solar system and across the universe.
The latest JWST observations focused on the HR 8799 system, which consists of four planets orbiting their host star about 130 light-years from Earth in the constellation Pegasus. Previous observations have shown four of them are more massive than Jupiter, and are in orbits with periods that range from decades to centuries. This system has long intrigued astronomers studying planet formation, largely because of its youth — at just 30 million years old, these planets still radiate leftover heat from their births, which JWST was able to observe in wavelengths that tease out the specific gases and other atmospheric details.
Links:
James Webb Space Telescope sees four giant alien planets circling nearby star

Strongest hints yet of biological activity outside the solar system / New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI - publication
2025-04-17
Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain cautious.
Using data from the James Webb Space Telescope (JWST), the astronomers, led by the University of Cambridge, have detected the chemical fingerprints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b, which orbits its star in the habitable zone. On Earth, DMS and DMDS are only produced by life, primarily microbial life such as marine phytoplankton. While an unknown chemical process may be the source of these molecules in K2-18b’s atmosphere, the results are the strongest evidence yet that life may exist on a planet outside our solar system. The observations have reached the ‘three-sigma’ level of statistical significance – meaning there is a 0.3% probability that they occurred by chance. To reach the accepted classification for scientific discovery, the observations would have to cross the five-sigma threshold, meaning there would be below a 0.00006% probability they occurred by chance. The researchers say between 16 and 24 hours of follow-up observation time with JWST may help them reach the all-important five-sigma significance. Their results are reported in The Astrophysical Journal Letters. Earlier observations of K2-18b — which is 8.6 times as massive and 2.6 times as large as Earth, and lies 124 light years away in the constellation of Leo — identified methane and carbon dioxide in its atmosphere. This was the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in the habitable zone.
Those results were consistent with predictions for a ‘Hycean’ planet: a habitable ocean-covered world underneath a hydrogen-rich atmosphere. However, another, weaker signal hinted at the possibility of something else happening on K2-18b. To determine the chemical composition of the atmospheres of faraway planets, astronomers analyse the light from its parent star as the planet transits, or passes in front of the star as seen from the Earth. As K2-18b transits, JWST can detect a drop in stellar brightness, and a tiny fraction of starlight passes through the planet’s atmosphere before reaching Earth. The absorption of some of the starlight in the planet’s atmosphere leaves imprints in the stellar spectrum that astronomers can piece together to determine the constituent gases of the exoplanet’s atmosphere. The earlier, tentative, inference of DMS was made using JWST’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph) instruments, which together cover the near-infrared (0.8-5 micron) range of wavelengths. The new, independent observation used JWST’s MIRI (Mid-Infrared Instrument) in the mid-infrared (6-12 micron) range. DMS and DMDS are molecules from the same chemical family, and both are predicted to be biosignatures.
Both molecules have overlapping spectral features in the observed wavelength range, although further observations will help differentiate between the two molecules. However, the concentrations of DMS and DMDS in K2-18b’s atmosphere are very different than on Earth, where they are generally below one part per billion by volume. On K2-18b, they are estimated to be thousands of times stronger – over ten parts per million. Madhusudhan says that while the results are exciting, it’s vital to obtain more data before claiming that life has been found on another world. He says that while he is cautiously optimistic, there could be previously unknown chemical processes at work on K2-18b that may account for the observations. Working with colleagues, he is hoping to conduct further theoretical and experimental work to determine whether DMS and DMDS can be produced non-biologically at the level currently inferred. While he is not yet claiming a definitive discovery, Madhusudhan says that with powerful tools like JWST and future planned telescopes, humanity is taking new steps toward answering that most essential of questions: are we alone? The James Webb Space Telescope is a collaboration between NASA, ESA and the Canadian Space Agency (CSA). The research is supported by a UK Research and Innovation (UKRI) Frontier Research Grant.
Links:
Strongest hints yet of biological activity outside the solar system
Wetenschappers vinden ‘sterkste tekenen tot nu toe’ van mogelijk buitenaards leven
Er is geen Planet K2-18B! bescherm het buitenaardse leven!

VPRO #Tegenlicht – Zo ontrafelt deze wetenschapper het geheim van exoplaneten (TV internet)
2025-09-07
Tegenlicht is een informatief televisieprogramma van de VPRO via het internet.
Door de VPRO wordt het programma bestempeld als documentaire op het vlak van politiek, economie, sociologie en wetenschap. Het programma stelt zich ten doel inzicht in de werking van de samenleving te verschaffen.
In deze aflevering zoeken we mee met sterrenkundige Casper Farret Jentink, die diep in de bossen boven Genève werkt aan een van de grootste vragen die de mensheid zich ooit stelde: zijn we alleen in het universum? We worden alleen geboren, we sterven alleen, en daartussenin proberen we te begrijpen wat het betekent om er überhaupt te zijn. In een werkplaats, half sterrenwacht, half sciencefiction-decor, bouwt sterrenkundige Casper Farret Jentink met Zwitserse precisie instrumenten die het licht van verre sterren tot op vijf siliciumatomen nauwkeurig kunnen meten, op zoek naar een tweede aarde. Exoplaneten, planeten die draaien om een andere ster dan de zon, zijn onzichtbaar voor het oog, maar traceerbaar via de dure speeltjes van onder andere Jentink. Er werden er al duizenden gevonden, maar geen enkele zoals onze eigen aarde. Jentink is vastbesloten daar verandering in te brengen, via zelfgebouwde instrumenten met namen als Ristretto en Espresso. Want als we leven vinden, of juist niet, zegt dat iets over onszelf. Zijn we een uniek en kwetsbaar kosmisch toeval? Of zijn we een van de velen, omdat het leven ondanks alle uitdagingen taai en volhardend is. En dat, zegt Jentink, zou nog het geruststellendste antwoord zijn dat de wetenschap ons ooit heeft gegeven.
Links:
Hoe je met zelfgebouwde machines het geheim van exoplaneten kunt ontrafelen

The Eschatian Hypothesis - publication
2025-12-10
The research article titled “The Eschatian Hypothesis” explains that the first detection of an astrophysical object is usually not representative of the overall type.
Instead, we first tend to detect things with large observational signatures, due to our detection methods and their biases. The history of astronomy is full of examples. The history of exoplanet detection illustrates the phenomenon. The very first exoplanets were found in the early 1990s orbiting pulsars. But now we know that those were not representative. In the NASA Exoplanet Archive of more than 6,000 exoplanets, fewer than 10 were found around pulsars. They were detected because pulsars are like exquisitely timed cosmic lighthouses, and orbiting exoplanets altered that exquisite timing noticeably. It had nothing to do with how plentiful these types of planets are. For decades, science fiction writers have tried their best to prepare us for eventual contact with aliens. Their efforts are dominated by several recurrent tropes. There’s the invasion by a warlike species, there’s the highly evolved species trying to communicate with our primitive species, there’s the benevolent aliens come to save us from ourselves, and there’s the mischievous anal-probers and medical experimenters. But those examples are highly unlikely to represent first contact, according to new thinking and research. Not just because they may be totally unrealistic, but because of what might motivate another species to contact us, and how that alters the observational signal they use to announce their presence.

Links:
First Contact With an Alien Civilization Could Be ‘Loud’. Here’s Why

Babelsberger Sternennächte – Exoplaneten-Atmosphären - Von regnenden Rubinen bis zur Suche nach Leben | Dr. Fabio Lesjak (TV webcast)
2026-04-16 20:00 - 21:00 (Europe/Amsterdam)
Die Leibniz-Instituts für Astrophysik Potsdam (AIP) Babelsberger Sternennächte finden online statt, in der Regel gibt es immer am 3. Donnerstag im Monat einen neuen Vortrag einer Wissenschaftlerin oder eines Wissenschaftlers des AIP, der ab 20 Uhr auf dem YouTube-Kanal von Urknall, Weltall und das Leben ausgestrahlt wird.
Dr. Fabio Lesjak, Wissenschaftler in der Forschungsgruppe Sternphysik und Exoplaneten am AIP, spricht zu „Exoplaneten-Atmosphären – Von regnenden Rubinen bis zur Suche nach Leben“. Ähnlich wie die Planeten in unserem Sonnensystem sind viele Exoplaneten von Atmosphären umgeben. Durch die Untersuchung dieser Atmosphären mit Hilfe hochauflösender Spektroskopie können Forschende Rückschlüsse auf die Zusammensetzung der Atmosphäre, ihre Temperatur und sogar über vorherrschende Winde ziehen.

Links:
Babelsberger Sternennächte
Babelsberger Sternennächte – playlist
