Nearly 300 hours with the Webb telescope for IREx astronomers!

Since its operations began in 2022, the James Webb Space Telescope (JWST) has made significant scientific advancements in the field of exoplanets, such as detecting carbon dioxide in the atmosphere of the hot Jupiter WASP-39 b or studying the exoplanet Trappist-1 b. However, not everyone gets the chance to observe with the JWST! Each year, the telescope’s team offers the international community the opportunity to propose observing programs of varying lengths and wide range of scientific objectives. Then, a committee composed of astrophysicists evaluate the proposals and choose who gets time. The competition is fierce: typically, only one in nine proposals is awarded observation time.

On March 11th, the Space Telescope Science Institute (STScI) revealed the results for Cycle 4. In total, 274 of the 2346 programs submitted were selected for this fourth year of JWST observations, which will take place between July 2025 and June 2026, for 8,500 hours of observation. As in previous cycles, Canada obtained a significant share of this observation time, with 11 programs led by Canadian researchers, totaling 10% of the total hours available.

The IREx team, with its unique expertise gained from previous cycles, notably thanks to its “guaranteed time observation” programs linked to Canada’s contribution to the construction of the telescope, secured a record 165 hours of observation time. Additionally, two recently graduated researchers from the University of Montreal had their projects selected, totaling 133 hours!

Here are the programs led by members of our team that were selected:

Probing Infernal Worlds

Lisa Dang. Photo provided by herself.

Principal Investigator (PI): Lisa Dang, postdoctoral researcher at IREx/UdeM
Co-Principal Investigators (Co-PI): N/A
Co-Investigators (Co-I): Nicolas Cowan, Mahesh Herath, Romain Allart, Joost Wardernier, Giang Nguyen from IREx, and 28 co-investigators from around the world
Time Awarded: 100.5 hours with the MIRI instrument, in low-resolution spectroscopy mode

Lava planets, rocky worlds that lie very close to their star, offer a unique opportunity to learn more about rocky exoplanets and their interiors. Heated to extremely high temperatures, these planets have a molten magma surface exposed and constantly evaporating.

Lisa Dang and her team propose to study five such worlds by observing their light with the MIRI instrument, which captures the mid-infrared. By tracking the evolution of these planets’ light over the course of their orbit around their star, they will be able to obtain “phase curves.” Upon comparing these phase curves, they hope to map their atmospheres and to understand what their interiors are made of.

More information on the program can be found on the STScI website: GO 8864: Probing the Infernal Worlds: Lava Planets as Time Capsules of Thermal Evolution.

Exploring Stellar Flares of Small Stars

Dhvani Doshi. Photo provided by herself.

Principal Investigator (PI): Dhvani Doshi, PhD student at IREx/McGill
Co-Principal Investigators (Co-PI): N/A
Co-Investigators (Co-I): Nicolas Cowan, Étienne Artigau, René Doyon, Olivia Lim, and 2 co-investigators from the United States
Time Awarded: 47.6 hours with the slitless spectroscopy mode on a single object using NIRISS

Low-mass stars, known as M dwarfs, are often very active, with powerful stellar eruptions. These events can complicate the detection and study of exoplanets orbiting these stars.

Dhvani Doshi and her team propose to study five of these active stars for 5-10 hours each, using the NIRISS instrument. Their goal is to create a comprehensive library of stellar eruptions in the near-infrared, with the aim of capturing up to 400 events. To date, few near-infrared observations have been published, although these flares play a crucial role in the study of exoplanets, particularly when they pass in front (transit) of or behind their star (eclipse), or when their light is analyzed during their orbit (phase curve). This project will provide a better understanding of how these flares influence the stars’ light, and further our knowledge of exoplanets that orbit them.

More information on the program can be found on the STScI website: GO 7068: Surveying Stellar Shenanigans: Exploring M dwarf Flares for Exoplanetary Insights.

Mapping the Ultra-Hot Jupiter KELT-20b

Antoine Darveau-Bernier et Joost Wardenier. Photos provided by the researchers.

Principal Investigator (PI): Joost Wardenier, postdoctoral researcher at IREx/UdeM
Co-Principal Investigators (Co-PI): Antoine Darveau-Bernier (former member of IREx/UdeM, now at Environment Canada) and Mark Hammond from the University of Oxford
Co-Investigators (Co-I): Lisa Dang, Nicolas Cowan, David Lafrenière, Louis-Philippe Coulombe, Loïc Albert; former IREx members Taylor Bell (STScI), Jake Taylor (University of Oxford), Anne Boucher (Environment Canada); summer interns Ying (Zoe) Shu, Alexandra Rochon, and 5 European co-investigators
Time Awarded: 16.7 hours with the NIRSpec instrument in bright object observation mode

“Ultra-hot Jupiters” are giant exoplanets that are very close to their star. Because of a phenomenon called “tidal locking”, they have a permanent “dayside” that always faces the star, and a “nightside” that is cast in perpetual darkness. This leads to extreme day-night temperature contrasts and very strong winds. With the advent of JWST, observations of these planets have reached incredible levels of detail. For a long time, observations of (ultra-)hot Jupiters were interpreted with 1D atmospheric models, which assume that the planet’s temperature and composition only vary with altitude. However, to correctly interpret the JWST data we need to account for the full 3D structure of the planet.

The team led by Joost Wardenier and Antoine Darveau-Bernier will use the NIRSpec instrument on the JWST to observe the ultra-hot Jupiter KELT-20 b. Using a technique known as “eclipse mapping”, which involves taking “snapshots” of the planet as it passes behind its star during its eclipse, they hope to construct the most accurate 3D temperature map of an exoplanet to date. This will provide valuable insights into heat redistribution in across atmospheres of ultra-hot Jupiter and guide the next generation of planetary climate models.

More information on the program can be found on the STScI website: GO 6978: The Dayside of the Coolest Ultra-Hot Jupiter, KELT-20b, Resolved with Eclipse Mapping.

Two Programs Supported by Former Members:

Unveiling the Nature of Super-Puffs

Michael Radica and Caroline Piaulet-G. Photos provided by themselves.

Principal Investigator (PI): Michael Radica (University of Chicago, IREx/UdeM alumnus)
Co-Principal Investigators (Co-PI): Caroline Piaulet-G. (University of Chicago, IREx/UdeM alumna)
Co-Investigators (Co-I): 6 co-investigators from the United States
Time Awarded: 94.6 hours with the MIRI instrument in low-resolution spectroscopy mode, NIRSpec in bright object observation mode, and NIRISS in slitless spectroscopy mode

Exoplanets known as “super-puffs” are worlds that have masses similar to Neptune, but radii similar to Saturn, which makes them quite mysterious. Their large size is difficult to explain using conventional planet formation models. They could be caused by very high internal temperatures or the presence of hazes, made up of tiny particles in their atmospheres, created by chemical reactions driven by the light from their host stars.

Michael Radica and Caroline Piaulet-G., former students of IREx now researchers at the University of Chicago, along with their team, aim to study four of these exoplanets with varying temperatures and masses: WASP-107 b, WASP-127 b, WASP-193 b, and TOI-1420 b. They will use three of the JWST’s instruments to analyze the light passing through their atmospheres across a wide range of wavelengths (colours). This will provide insights into the composition of their atmospheres and the physical and chemical phenomena that explain their large size and formation.

More information on the program can be found on the STScI website: GO 9101: Unveiling the Nature of Super-Puffs: A Panchromatic Transmission Spectroscopy Survey.

Revealing the Chemistry and Formation of Exo-Neptunes

Caroline Piaulet-G. Photos supplied by herself.

Principal Investigator (PI): Caroline Piaulet-G. (University of Chicago, IREx/UdeM alumna)
Co-Principal Investigators (Co-PI): N/A
Co-Investigators (Co-I): Björn Benneke, Louis-Philippe Coulombe, Pierre-Alexis Roy, Romain Allart from IREx, former members Stefan Pelletier (Geneva Observatory) and Michael Radica (University of Chicago), and 12 other co-investigators from the United States and Europe
Time Awarded: 38 hours with the MIRI instrument in low-resolution spectroscopy mode, NIRSpec in bright object observation mode, and NIRISS in slitless spectroscopy mode

Among known exoplanets, many have sizes and masses similar to Neptune. These “exo-neptunes” are less common than smaller planets, but much more frequent than giant gas planets very close to their stars (the famous hot Jupiters, which have been heavily studied). They are important because they can help us understand how Neptune and Uranus formed in our own Solar System. However, studying these planets is challenging due to the presence of clouds and fog in their atmosphere.

Caroline Piaulet-G. and her team want to study the exo-neptune TOI-674 b, which has a temperature of about 370°C. Using three of JWST’s instruments, they will analyze the planet’s light at different wavelengths (colors) to better understand its atmosphere. They will look for signs of clouds and fog, how the chemistry of the atmosphere works, and if there are indications of high internal heat, possibly caused by friction between the planet and its star. These observations will help us better understand all exo-neptunes and their formation and evolution.

More information on the program can be found on the STScI website: GO 9095: Combining Emission and Transmission Spectroscopy to Reveal Exo-Neptune Aerosols, Chemistry, and Formation.

Many other programs from JWST’s Cycle 4 will be supported by Canadian researchers and IREx as co-investigators. To view all selected GO programs, visit the STScI website.

Congratulations to all the astronomers who were awarded time, and to all astronomers who submitted proposals!

The next call for proposals for Cycle 5 of the JWST GO program is expected in August 2025, with a submission deadline likely in the fall.