Category Archives: James Webb Space Telescope

JWST maps the weather on exoplanet WASP-43b

NASA has put out a press release about observations of WASP-43b with the James Webb Space Telescope. The paper in Nature Astronomy, led by Taylor Bell, reports observations around the orbit with the MIRI instrument.

JWST/MIRI phase curve of WASP-43b (Image Credit: NASA, ESA, CSA, Ralf Crawford (STScI)).

“An international team of researchers has successfully used NASA’s James Webb Space Telescope to map the weather on the hot gas-giant exoplanet WASP-43 b.

“Precise brightness measurements over a broad spectrum of mid-infrared light, combined with 3D climate models and previous observations from other telescopes, suggest the presence of thick, high clouds covering the nightside, clear skies on the dayside, and equatorial winds upwards of 5,000 miles per hour mixing atmospheric gases around the planet.

“The investigation is just the latest demonstration of the exoplanet science now possible with Webb’s extraordinary ability to measure temperature variations and detect atmospheric gases trillions of miles away.”

The visibility of the heated face of the planet varies around the orbit, producing the above “phase curve” variation. (Image Credit: NASA, ESA, CSA, Ralf Crawford (STScI))

“Sand clouds” detected by JWST in the atmosphere of WASP-107b

A press release by KU Leuven announced the detection of clouds made of sand in the atmosphere of WASP-107b. The research, published in Nature by Achrène Dyrek et al. used observations with the James Webb Space Telescope to find clouds made of silicates, MgSiO3, SiO2 and SiO.

Transmission spectrum of WASP-107b, including the contribution of sand clouds. Image credit: Michiel Min, Europese MIRI EXO GTO team, ESA, NASA

“The fact that it has such a very puffy atmosphere enables us to really look very deep inside the atmosphere of the planet,” Leen Decin, a professor from KU Leuven and one of the study’s lead authors, told Euronews Next.

The astronomers also found that the clouds in the exoplanet’s atmosphere are made up of silicon, which is the main component of sand.

“It is the first time in history that we can deduce the composition of the clouds. And so here are sand clouds, very, very small sand clouds and they exist very high up in the atmosphere of the planets,” Decin told Euronews.

Michiel Min, from the Netherlands Institute for Space Research, said in a statement that the sand clouds high in the atmosphere have a similar cycle to the water vapour and cloud cycle on Earth but with “droplets made of sand”.

Decin says you could also think of it as solid clusters of sand on an exoplanet with extremely high wind speeds of a few kilometres per second.

The press release led to widespread media coverage, including The BBC, The Guardian, Daily Mail, and Newsweek.

NASA’s Webb identifies methane in the atmosphere of WASP-80b

Recently, NASA wrote a piece describing the discovery of the molecule methane in the atmosphere of WASP-80b, as announced by Taylor Bell et al. in Nature.

An artist’s rendering of the warm exoplanet WASP-80 b whose color may appear bluish to human eyes due to the lack of high-altitude clouds and the presence of atmospheric methane identified by NASA’s James Webb Space Telescope. Image credit: NASA.

Taylor Bell explains: “NASA has a history of sending spacecraft to the gas giants in our solar system to measure the amount of methane and other molecules in their atmospheres. Now, by having a measurement of the same gas in an exoplanet, we can start to perform an “apples-to-apples” comparison and see if the expectations from the solar system match what we see outside of it.”

The measured transit spectrum (top) and eclipse spectrum (bottom) of WASP-80 b from NIRCam’s slitless spectroscopy mode on NASA’s James Webb Space Telescope. In both spectra, there is clear evidence for absorption from water and methane whose contributions are indicated with colored contours. Image Credit: BAERI/NASA/Taylor Bell.

The NASA piece led to widespread reporting of the finding on numerous websites.

Quartz Crystal clouds in the atmosphere of gas-giant exoplanet WASP-17b

NASA has put out a press release about JWST observations of the bloated gas-giant exoplanet WASP-17b.

“Researchers using NASA’s James Webb Space Telescope have detected evidence for quartz nanocrystals in the high-altitude clouds of WASP-17 b, a hot Jupiter exoplanet 1,300 light-years from Earth. The detection, which was uniquely possible with Webb’s MIRI (Mid-Infrared Instrument), marks the first time that silica (SiO2) particles have been spotted in an exoplanet atmosphere.”

Waves of light detected in the clouds of the hot gas giant exoplanet WASP-17 b revealed the presence of quartz (crystalline silica, SiO2), as shown in this graph. Credit: NASA, ESA, CSA, and R. Crawford (STScI).

“Silicates (minerals rich in silicon and oxygen) make up the bulk of Earth and the Moon as well as other rocky objects in our solar system, and are extremely common across the galaxy. But the silicate grains previously detected in the atmospheres of exoplanets and brown dwarfs appear to be made of magnesium-rich silicates like olivine and pyroxene, not quartz alone – which is pure SiO2.”

““We fully expected to see magnesium silicates,” said team member Hannah Wakeford, “But what we’re seeing instead are likely the building blocks of those, the tiny ‘seed’ particles needed to form the larger silicate grains we detect in cooler exoplanets and brown dwarfs.”

The atmosphere of the hot gas giant planet WASP-17 b, depicted in this artist’s concept, is composed primarily of hydrogen and helium, along with small amounts of water vapor and hints of carbon dioxide and other molecules. Credit: NASA, ESA, CSA, and R. Crawford (STScI)

“WASP-17 b is one of three planets targeted by the JWST Telescope Scientist Team’s Deep Reconnaissance of Exoplanet Atmospheres using Multi-instrument Spectroscopy (DREAMS) investigations, which are designed to gather a comprehensive set of observations of one representative from each key class of exoplanets: a hot Jupiter, a warm Neptune, and a temperate rocky planet.”

The press release has led to widespread coverage on websites and media outlets.

Water vapour in the atmosphere of WASP-18b

NASA have put out a press release about observations of the ultra-hot gas-giant WASP-18b by the James Webb Space Telescope.

By measuring the radiation of the planet as it is eclipsed by its host star, once every orbit, the team, led by Louis-Philippe Coulombe, mapped out the heat of the planet’s atmosphere. With WASP-18b being so hot, water vapour is likely disassociated over much of the “day side” of the planet, where it is blasted by the host-star’s radiation. But the sensitivity of JWST allowed it to detect water vapour from cooler regions on the planet’s limbs.

James Webb detects carbon dioxide in the spectrum of WASP-39b

The first science paper about a transiting exoplanet observed by JWST reports the detection of carbon dioxide in the spectrum of WASP-39b.

NASA’s press release on the “Early Release Science” result gives this image:

In addition they have produced this graphic of how transit spectroscopy works:

James Webb’s spectrum of clear-skies exoplanet WASP-96b

Among the first 5 images released from the James Webb Space Telescope is its first spectrum of an exoplanet, WASP-96. This shows the clear detection of water vapour, and is the first taster of many such results to come:

Here is the transit light-curve from which the spectrum derives:

The JWST results have been reported in a large fraction of the world’s media outlets. This is the first time the spectrum of an exoplanet has lit up New York’s Times Square:

Of numerous media articles on WASP-96b, here is a typical example from The Atlantic.

No clouds on the dayside of WASP-43b

As you’ll likely know from flying in an aircraft above the weather, clouds are bright, they reflect a lot of sunlight. This means that if a hot-Jupiter exoplanet has a cloudy atmosphere, then it should also be relatively bright, and so we should be able to detect a discernible drop in light when it it eclipsed behind its host star.

A new paper by Jonathan Fraine et al analyses data obtained with the Hubble Space Telescope WFCS/UVIS instrument to look for the eclipse of WASP-43b. Here is the result (with the data compared to model eclipse profiles):

The authors find no significant eclipse, deriving only an upper limit to any drop in light of 67 parts-per-million, which means that the dayside face of the planet is reflecting less than 6% of the illuminating starlight. And that means “that we can rule out a high altitude, bright, uniform cloud layer”.

Fraine et al remark that “Because of its observational and atmospheric viability for spectroscopic detections, WASP-43b has become a benchmark planet for current and future hot Jupiter observations. Upcoming … JWST observations [will] map the thermal structure and chemical composition of this exoplanet with exquisite detail … We expect that no other exoplanet has or will be observed with this much precision and wavelength coverage for many years to come.”

The importance of cloud-free skies is that one can then see atomic and molecular spectral features much more readily, and so learn much more about the atmosphere’s composition.

WASP-62b, in James Webb’s continuous-viewing zone, has a clear atmosphere

James Webb’s “Continuous Viewing Zone” is the patch of sky where the satellite can point continuously at a target and so observe it most efficiently. Exoplanets within the CVZ that are suitable for atmospheric characterisation are thus of high importance, and so far WASP-62b is the only gas giant known within the CVZ.

Munazza Alam et al have now pointed the Hubble and Spitzer space telescopes at WASP-62b to see what its atmosphere looks like. Importantly, they find that WASP-62b has clear skies. This matters since cloudy or haze-filled atmospheres tend to produce flat spectra lacking any spectral features, and so don’t tell us much.

Here, Alam et al plot the spectrum near the sodium (Na) line, showing that it has a broad base, akin to that in the clear-skied planet WASP-96b. The broad base of the line means that it is being widened by “pressure broadening”, and that can only happen deep in the planet’s atmosphere where the pressure is high. And we can only see deep into the atmosphere if it is clear rather than cloudy.

Clear skies mean that spectral features produced by the molecules in the atmosphere should be readily detectable with JWST. Here Alam et al simulate what we expect to see with JWST, showing that Na, H2O, NH3, FeH, SiH, CO, CO2, and CH4 can all be detected.

They conclude by saying that: “As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.

Looking forward to WASP-79b with JWST

The bloated hot-Jupiter WASP-79b has been selected as an Early Release Science target for the James Webb Space Telescope, so is being studied with current facilities such as HST and Spitzer.

Here is a simulation of what the spectrum of WASP-79b might look like when observed with JWST, taken from a new paper by Kristin Sotzen et al.

Sotzen et al have collected together data from HST, Spitzer and the Magellan telescope in order to model the atmosphere of the planet and use that to predict the results of the JWST observations. The different coloured symbols are for different instruments of JWST, namely NIRSpec, NIRCam and NIRISS. The main spectral features are caused by water and carbon dioxide molecules. With a partially cloudy atmosphere and detectable water features, Sotzen et al confirm that WASP-79b is a prime target for JWST.