CHEOPS sees a “glory” effect on WASP-76b

The European Space Agency have put out a press release reporting the observation of a “glory effect” in observations of ultra-hot-Jupiter WASP-76b by the CHEOPS satellite.

“Cheops intensively monitored WASP-76b as it passed in front of and around its Sun-like star. After 23 observations over three years, the data showed a surprising increase in the amount of light coming from the planet’s eastern ‘terminator’ – the boundary where night meets day.”

Artist impression of glory on exoplanet WASP-76b (Credit: ESA)

“This discovery leads us to hypothesise that this unexpected glow could be caused by a strong, localised and anisotropic (directionally dependent) reflection”, said Olivier Demangeon, lead author of the study, producing a glory effect akin to a rainbow.

“You need atmospheric particles that are close-to-perfectly spherical, completely uniform and stable enough to be observed over a long time. The planet’s nearby star needs to shine directly at it, with the observer – here Cheops – at just the right orientation.”

“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.

The changing atmosphere of WASP-121b

NASA have put out a press release about observations of hot-Jupiter exoplanet WASP-121b. A team led by ESA scientist Quentin Changeat analysed observations with the Hubble Space Telescope made in 2016, 2018 and 2019 to find distinct differences in the atmosphere of the planet, revealing that planets have weather patterns.

The figure below shows the “phase curve”, a smooth variation caused by the varying visibility of the heated face of the planet (there are also sharp dips caused by the eclipse and transit of the star/planet). Differences between the phase curve in different years indicate changes in the atmosphere.

Heat maps of WASP-121b show the changing temperatures of the irradiated face of WASP-121b.

The press release has led to articles on WASP-121b on dozens of websites across the world.

WASP-69b’s comet-like tail

The Keck Observatory have put out a press release saying that WASP-69b’s comet-like tail is at least 350,000 miles long, 7 times bigger than the planet itself. The tail results from evaporation of the planet’s atmosphere, caused by irradiation by its hot star.

The observations, reported in a paper led by Dakotah Tyler, a PhD student at UCLA, used the Keck/NIRSPEC spectrograph to study helium atoms in material boiling off the planet. They observed a transit of the planet across the face of its star, and detected helium absorption long after the transit itself had ended, showing that a plume of escaping gas was still absorbing some of the starlight.

An artist’s impression of evaporating planet WASP-69b and its comet-like tail. (Credit: W. M. Keck Observatory/Adam Makarenko)

“The WASP-69b system is a gem because we are able to study its atmospheric mass-loss in real-time,” says co-author, Erik Petigura. “This makes for a rare opportunity to understand the critical physics that shapes thousands of other planets.”

Helium absorption (yellow/green) is still seen after the end of transit (contact time T4), revealing the cometary tail.

The press release has led to coverage on multiple webpages, including in The New York Times, Newsweek, Arab Times, Forbes, Salon and others.

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.

The IAU names more WASP exoplanets

The International Astronomical Union is periodically running contests to allow young people worldwide to name exoplanets, including those found by the WASP project.

Results of the 2022/23 naming process have just been announced.

The star WASP-19 is named Wattle (a genus of 1000 species of shrubs and trees native to Australia) while planet WASP-19b is Banksia (a genus of Australian wildflowers of medicinal and cultural importance to indigenous Australians).

The star WASP-43 is named Gnomon (after the astronomical instrument) while planet WASP-43b is Astrolábos (Greek for the astronomical instrument used in navigation).

The star WASP-63 is named Kosjenka while planet WASP-63b is Regoč (the names being characters in a popular Croatian fairy tale).

The star WASP-69 is named Wouri while planet WASP-69b is Makombé (being a major river in Cameroon and its tributary).

The star WASP-121 is named Dilmun (the Sumerian name of an ancient civilisation of the Bahrain archipelago) while planet WASP-121b is Tylos (the ancient Greek name for Bahrain island.).

The star WASP-166 is named Filetdor while planet WASP-166b is Catalineta (being a sea-serpent and heroine from the Mallorcan folktale “Na Filet d’Or”).

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.

Cold-trapping on the nightside of giant exoplanet WASP-76b

The University of Montreal have put out a press release about a study of ultra-hot-Jupiter WASP-76b. The work, published in Nature by Stefan Pelletier et al, is based on observations with the 8-m Gemini-North telescope.

Pelletier et al measure the abundances of elements in the atmosphere of WASP-76b and compare them to abundances in the Sun.

Elements with condensation temperatures below 1550 K match solar abundances. Elements with higher condensation temperatures appear to be severely depleted. This is likely because they are “cold trapped”, condensed on the night-side of the planet, which, facing away from its host star, is much colder. The work has been widely reported in the media.

A hot super-Earth in the WASP-84 planetary system

When Kepler’s K2 mission started monitoring planetary systems where WASP had previously found hot Jupiters, one of the early discoveries was extra planets in the WASP-47 system, small rocky planets with transits too shallow to have been found by WASP.

Now, a similar finding for the WASP-84 system has been announced by Gracjan Maciejewski etal. WASP found a Jupiter-sized planet in an 8-day orbit, while lightcurves from NASA’s TESS satellite also show a super-Earth planet with an orbit of 1.4 days.

The mass of both planets can be gained from the radial-velocity motion of the host star:

The new planet has a rocky, Earth-like composition.