Plus the new pieces, research, and promising telescope that might lead to the answers.
The torrential autumn downpours of Nashville are nothing compared to the otherworldly storms on planets beyond our galaxy. Even deadlier than the sulfuric acid that rains on the Venusian surface and the thunderstorms of diamond rains on Saturn and Jupiter, is the liquid iron that may hail from the skies of WASP-76b. Discovered in 2016, WASP-76b orbits in the constellation Pisces. It is an ultra-hot Jupiter: one of the many exoplanets that share similarities with our own Gas Giant. The atmospheres of these exoplanets are pyretic temperatures and it is relentlessly stuck in a terminal sunniness. To add, research confirms the presence of strong day-night winds. WASP-76b in particular has temperatures as high as 2,000 degrees Celsius (or 3,600 degrees Fahrenheit); so hot the water molecules in the atmosphere are completely torn apart. They are hellish places, akin to netherworlds and alien planets conceptualized in science fiction. The leading question in the study of ultra-hot Jupiters interrogates what in their atmosphere allows for a world hotter than hellfire, and recent research that utilizes a new technique of examining these far away planetary bodies adds another puzzle piece to the unfinished scape of its atmospheric formation.
Better understood as “star-planet hybrids,” exoplanets are planets that orbit around a star outside of the solar system. 4,500 have already been discovered, all of which are incredibly far away from our home on Earth. Immediately capturing the curiosity of scientists, hot Jupiters—kin to ultra-hot Jupiters—were the first broadly studied type of exoplanet, beginning in the mid-1990s. Hot-Jupiters are thought to be akin to Jupiter and Saturn due to their short orbital patterns. They are perplexing spheres of gas and the collective fascination around them has led to extensive study over the years. They are found around 1% of star-like stars, a percentage which is quite large considering the expansiveness of our known and unknown universe. Around 700 have been formally discovered in our galaxy.
Despite questions still existing around the channels of hot Jupiters, a new wave of scientific curiosity revolves around ultra-hot Jupiters. To quote researcher Emily Deibert via The Conversation, WASP-76b in particular, can “offer us a window into the most extreme physical and chemical processes in our galaxy, and studying its harsh alien conditions can help us place our own solar system into context.”
WASP-76b is an ideal case study for a variety of reasons, but mainly because of its large extended atmosphere, a key characteristic when studying planetary bodies lightyears away from the telescope and the humans behind it. This extensive atmosphere leaves strong chemical imprints on its starlight. This makes it easier to observe through a method known as transit spectrometry. When an exoplanet transits its parent star, the light from the star filters through the exoplanet’s atmosphere, leaving clues on the starlight of the types of gases in the atmosphere. When able to learn which gases are present through these chemical imprints, astronomers can learn more about the conditions present on the exoplanet.
In a new study, WASP-76b was the first exoplanet to be observed by the ExoGemS (Exoplanets with Gemini Spectroscopy) survey, neoteric method of exploring planetary diversity. Utilizing the Gemini North telescope in Hawaii, the goal of the study was to peak into the atmospheres of over 40 exoplanets. WASP-76b has been previously studied by almost every major telescope on Earth, from Chile's Very Large Telescope to NASA’s Hubble Space Telescope, currently floating 340 miles above Earth’s surface. Led by Emily Deibert at University of Toronto, and Jake Turner, Ray Jayawardhana and Andrew Ridden-Harper of Cornell University, observations by the ExoGemS would add another piece to the puzzle of evidence necessary to understand exactly what is happening in the puzzling atmosphere of the ultra-hot world.
A stand out in their findings was the chemical clue of ionized calcium—calcium atoms that have lost an electron. This is significant because, while previous research has detected this chemical imprint in the WASP-76b atmosphere, the amount of ionized calcium they observed vastly surpassed the amount predicted in their theoretical models. This leads the researchers to hypothesize a number of possibilities as to why this is happening and what it indicates.
The first possibility is that an extremity in temperature has caused normal calcium atoms to lose electrons, making them iodized. Thus, perhaps the already hellish temperature of WASP-76b is much hotter than the researchers’ 2,400 degrees celsius hypothesis.
The second possibility is that vigorous winds are unearthing ionized calcium atoms from the depths of the exoplanetary surface. This possibility is supported by previous research that indicates rapid winds whirling through the ultra-hot Jupiter as fast as 22 kilometers per a second. For comparison, the wind speed world record on Earth occurred in a tropical cyclone, traveling at is 408 kilometers per an hour which converts to 0.113 kilometers per a minute.
Similar observations were observed from another telescope across the world in Spain at the Calar Alto Observatory. The researchers note that the next piece of the puzzle will come from the James Webb Space Telescope, reportedly the “most powerful telescope ever,” by CNN space and science writer Ashley Strickland.
NASA is set to launch the long-anticipated telescope on December 18, taking off from Kourou French Guiana, past our atmosphere, and into the interstellar realm to reveal the hidden regions of space, look at every era of cosmic history, and significantly focus on planet formation, with the goal to add to the body of research collected by NASA's ongoing planet-pursuit mission: Transiting Exoplanet Survey Satellite (TESS), and Spitzer Space Telescope. Not only will Webb be able to categorize exoplanets, but it may also be able to explore planetary formation.
The Webb Telescope is intended to build off the work of Spitzer. An early project of Spitzer was observation of WASP-76b. Since, a series of other telescopes have observed the same exoplanet, all eyes on it from lightyears away. Perhaps as Webb observes it from the sky, more crucial pieces will fall into place as astronomers attempt to solve the puzzle of the atmosphere that reigns over the hellish world of ultra-hot Jupiters.
Just like the formation of the James Webb Telescope, the place astronomers are at now in exoplanet observation has been decades in the making. To quote Turner via the Cornell Chronicle, “Our work, and that of other researchers, is paving the way for exploring the atmospheres of terrestrial worlds beyond our solar system.”