Artistic representation of the exoplanet WASP-121 b. This planet always presents the same face to its star. This day side is thus continuously illuminated, and very hot, while the other, the night side, is constantly exposed to the coldness of space. Credit: Engine House VFX / MPIA.
Astronomers explore the unusual atmospheric conditions of a hot exoplanet
An international group of astronomers which includes Jake Taylor, a Postdoctoral Researcher at the Institute for Research on Exoplanets, has made the first detailed measurement of atmospheric nightside conditions of a tidally locked hot Jupiter. By including measurements from the dayside hemisphere, they determined how water changes physical states when moving between the hemispheres of the exoplanet WASP-121 b. While airborne metals and minerals evaporate on the hot dayside, the cooler night side features metal clouds and rain made of liquid gems. This study, published on February 21st in Nature Astronomy, is a big step in deciphering the global cycles of matter and energy in the atmospheres of exoplanets.
The first discovery of an exoplanet orbiting a Sun-like star more than 25 years ago introduced a new and exotic class of planets, hot Jupiters: Jupiter-like giant gas planets on close orbits around their parent stars, separated by only a few stellar diameters. Due to their proximity, the irradiation from the star heats the planet to several hundred to a few thousand degrees Celsius. Of the almost 5000 known exoplanets, more than 300 are such hot Jupiters.
Using the Hubble Space Telescope, the international team led by Thomas Mikal-Evans from the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, investigated the atmospheric properties of the hot Jupiter WASP-121 b. Astronomers discovered this exoplanet in 2015. It is located in the constellation Puppis at a distance of 855 light-years from Earth. WASP-121 b’s mass is about 20% greater than that of Jupiter, while it has a diameter that is nearly twice as large.
“Despite the discovery of thousands of exoplanets, we’ve only been able to study the atmospheres of a small fraction due to the challenging nature of the observations,” Mikal-Evans points out. “So far, most of these measurements have provided limited information, such as basic details on the chemical composition or average temperature in specific subregions of the atmosphere.”
The first exploration of an exoplanet’s nightside environment
The new observations allowed the astronomers to obtain the most detailed insight yet into the conditions of an exoplanet nightside hemisphere. Like all hot Jupiters, WASP-121 b’s rotation is tidally locked to its orbit around its parent star. Hence, one 30-hour orbit around the star requires the same amount of time as the planet needs to rotate once on its axis. As a result, the hemisphere pointing towards the star – the dayside – always suffers the roasting hot stellar surface. Likewise, the cooler night side constantly faces the cold and dark space. By merging the data from the dayside and nightside hemispheres, the team’s analysis leads to the first elaborate view of how an exoplanet atmosphere functions as a global system.
Metal clouds and rain made of liquid gems
Liquid ruby and sapphire could be raining into the atmosphere of the gas giant exoplanet WAPS-121 b. Credit: Wikimedia Commons (ruby, sapphire).
Instead of water clouds such as those on Earth, clouds on WASP-121 b mainly consist of metals such as iron, magnesium, chromium and vanadium. Previous observations have revealed the spectral signals of these metals as gases on the hot dayside. The new Hubble data indicate that temperatures drop low enough for the metals to condense into clouds on the nightside. Eastward flowing winds that carry the water vapour across the nightside would also blow these metal clouds back around to the dayside, where they again evaporate.
Strangely, aluminium and titanium were not among the gases detected in the atmosphere of WASP-121 b. A likely explanation for this is that these metals have condensed and rained down into deeper layers of the atmosphere, not accessible to observations. This rain would be unlike any known in the Solar System. For instance, aluminium condenses with oxygen to form the compound corundum. With impurities of chromium, iron, titanium or vanadium, we know it as ruby or sapphire. Liquid gems could therefore be raining on the nightside hemisphere of WASP-121 b.
Prospects with the James Webb Space Telescope
Jake Taylor, NEAT Postdoctoral Fellow at the Institute for Research on Exoplanets (iREx) and co-author of the study, specialises in analysing space telescope data that reveal the atmosphere of exoplanets. He contributed to establishing the composition and structure of WASP-121 b’s atmosphere using Hubble Wide Field Camera 3 data.
Jake Taylor, NEAT Postdoctoral Fellow at the Institute for Research on Exoplanets (iREx), is a co-author of the study.
“WASP-121 b will be studied with the James Webb Space Telescope soon,” explains Dr.Taylor. “These Hubble observations give us a first insight into what the NEAT GTO observation for WASP-121 b will tell us about the extreme weather conditions on this planet.”
Jake joined iREx at the Université de Montréal in the Summer of 2021 specifically to work on NEAT, the James Webb Space Telescope observing program that uses Canadian Guaranteed Time Observations (GTO) to study a variety of exoplanets’ atmospheres, including that of WASP-121 b.
By covering wavelengths beyond Hubble’s range, the Webb Telescope’s observations will allow the team to determine the amount of carbon in the atmosphere, which could hold clues about how and where WASP-121 b formed in the protoplanetary disk. The measurements will even be precise enough to learn about the wind speeds at different altitudes inside the atmosphere.
Everyone at iREx and in the international team is eager to learn more about WASP-121 b with the Webb Telescope!
About this study
“Diurnal variations in the stratosphere of the ultrahot giant exoplanet WASP-121b ” by Mikal-Evans et al. was published on February 21th, 2022, in Nature Astronomy.In addition to Thomas Mikal-Evans (MPIA, Germany; MIT Kavli Institute, USA) and Jake Taylor (iREx, UdeM, Canada; University of Oxford, UK), the team includes 10 co-authors from the USA, UK and India.
Dr. Markus Nielbock Max-Planck-Institut für Astronomie Presse- und Öffentlichkeitsarbeit MPIA-Campus Königstuhl 17 D-69117 Heidelberg Tel. +49(0)6221 528-134 Mobil +49(0)15678 747326, nielbock@mpia.de
Media Contact Marie-Eve Naud EPO Coordinator, Institute for Research on Exoplanets Université de Montréal, Montréal, Canada 514-279-3222, marie-eve.naud@umontreal.ca
Nathalie Ouellette Coordinator, Institute for Research on Exoplanets Université de Montréal, Montréal, Canada 613-531-1762, nathalie.ouellette.2@umontreal.ca
Scientific Contacts Jake Taylor NEAT Postdoctoral Researcher Université de Montréal, Montréal, Canada jake.taylor@umontreal.ca
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
