From The University of Toronto (CA) via The Conversation : “Weird weather-Metal rain and super-high temperatures on an ultra-hot exoplanet”

From The University of Toronto (CA)


The Conversation

November 9, 2021

Emily Deibert, The University of Toronto (CA)

An artist’s impression of the exoplanet WASP-76b, which is hot enough to vaporize metals. Credit: M. Kornmesser/ The European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte](EU)(CL).

Ultra-hot Jupiters — named as such because of their physical similarities to the planet Jupiter — are exoplanets that orbit stars other than the sun with temperatures so high that the molecules in their atmospheres are completely torn apart. They are among the most extreme environments in our galaxy.

They also whip around their parent stars in orbits that only last a few days, and astronomers still aren’t sure how it’s possible for them to form [The Astrophysical Journal Letters].

While these harsh conditions might sound like they’re as extreme as it gets, astronomers are starting to realize they may just be the tip of the (very hot) iceberg. In a recent study published in The Astrophysical Journal Letters, my colleagues and I discovered that one of these exotic worlds in particular is even more extreme than we’d ever thought.

Ultra-hot worlds

Discovered in 2016 [Astronomy & Astrophysics], WASP-76b is perhaps the most well-known of these ultra-hot worlds. At double the size of our own planet Jupiter, WASP-76b has day-side temperatures reaching a whopping 2,400 C, and takes less than two days to orbit its parent star. Its claim to fame, however, is a 2020 study suggesting that liquid iron might literally be raining down from its skies.

More recent research, yet to be peer-reviewed, has called this result into question. But there’s no doubt that the conditions on WASP-76b are totally unlike anything here on Earth. WASP-76b can therefore 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.

Atmospheric knowledge

Unfortunately, studying exoplanets — even massive ones like WASP-76b — is often easier said than done. The 4,500 exoplanets already discovered [Caltech IPAC-Infrared Processing and Analysis Center (US)] are incredibly far away from us, and their parent stars are so bright that light from the exoplanets themselves gets completely washed out.

Rather than looking at the exoplanets directly, we often have to find ways to infer their presence instead. These indirect methods have actually been responsible for most of the exoplanets we’ve discovered. As a bonus, we can use these methods to peer into the exoplanets’ atmospheres as well.

This is the idea behind transit spectroscopy. When an exoplanet passes in front of, or transits, its parent star, the light from the star gets filtered through the exoplanet’s atmosphere. Different atmospheric gases leave unique chemical imprints — like fingerprints — on the starlight, and by studying these fingerprints, we’re able to learn which gases are present. This can help us learn more about what conditions on the exoplanet are actually like.

In theory, you can do this for any exoplanet with an atmosphere, but it’s easiest with atmospheres that are hot and puffed-up. Large, extended atmospheres leave stronger chemical imprints on their starlight, which makes them much easier for us to observe.

This is precisely why our team chose WASP-76b as one of the first exoplanets to be observed by our new ExoGemS (Exoplanets with Gemini Spectroscopy) survey. Led by Jake Turner, Ray Jayawardhana and Andrew Ridden-Harper at Cornell University (US), the goal of the survey is to glimpse into the atmospheres of more than 40 exoplanets using the Gemini North telescope in Hawaii.

National Science Foundation(US) NOIRLab’s Gemini North Frederick C Gillett telescope at Mauna Kea Observatory Hawai’i (US) Altitude 4,213 m (13,822 ft)

Extreme atmospheres

In this particular study, we observed WASP-76b for a period of four hours as it transited in front of its parent star. We were searching for the chemical fingerprints of metals in its atmosphere, because at these extreme temperatures, metals will actually vaporize into gas.

WASP-76b had already been observed many times in the past, but our observations from the Gemini North telescope reached redder wavelengths of light than previously published results. This meant that we could search for chemical fingerprints that previous studies didn’t have access to, shedding a much broader light on the exotic composition of this extreme world.

What immediately stood out to us in our data was a series of three very strong absorption features at infrared wavelengths of light. We recognized these as the chemical fingerprint of ionized calcium — calcium atoms that have lost an electron — and the signal was so strong that we could actually see it moving around as the exoplanet orbited its parent star.

A ‘fly to’ WASP-76, the star around which WASP-76b orbits.
A video by the European Southern Observatory showing the ultra-hot giant exoplanet WASP-76b.

Finding calcium in WASP-76b’s atmosphere wasn’t particularly surprising — a different set of calcium signals had already been detected earlier this year [Astronomy & Astrophysics]. What did surprise us was just how much ionized calcium we were seeing — much more than any of our theoretical models predicted we would.

So what’s going on? One possibility is that WASP-76b’s atmosphere is even hotter than the 2,400 C we’d previously thought. These extreme temperatures would strip electrons off of regular calcium atoms and the hotter the temperature, the more frequently this is going to occur.

Another possibility is that powerful winds are unearthing ionized calcium atoms from the exoplanet’s depths. A recent study actually suggested that WASP-76b may have winds as fast as 22 kilometres per second [Astronomy & Astrophysics]. For reference, the fastest winds ever measured on the Earth had a speed of less than one kilometre per second.

In a fortunate coincidence, another team of astronomers used observations from the Calar Alto Observatory in Spain to detect this same ionized calcium signal in infrared light.

Calar Alto Astronomical Observatory 3.5 meter Telescope, located in Almería province in Spain on Calar Alto, a 2,168-meter-high (7,113 ft) mountain in Sierra de Los Filabres(ES)

Like us, their data showed more ionized calcium than expected. There’s clearly much more going on in WASP-76b’s atmosphere than we’d thought [Astronomy & Astrophysics].

Weird, wild atmosphere

WASP-76b has been observed by just about every major telescope out there, from the Gemini North telescope in Hawaii to the Very Large Telescope in Chile all the way up to the Hubble Space Telescope in outer space.

European Southern Observatory(EU) , Very Large Telescope at Cerro Paranal in the Atacama Desert •ANTU (UT1; The Sun ) •KUEYEN (UT2; The Moon ) •MELIPAL (UT3; The Southern Cross ), and •YEPUN (UT4; Venus – as evening star). Elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo.

National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation](EU) Hubble Space Telescope

To fully piece together the puzzle of what’s going on its atmosphere, we’ll need to wait for observations from the powerful new James Webb Space Telescope set to launch in December 2021.

National Aeronautics Space Agency(USA)/European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ Canadian Space Agency [Agence Spatiale Canadienne](CA) Webb Infrared Space Telescope(US) James Webb Space Telescope annotated. Scheduled for launch in October 2021 delayed to December 2021.

In the meantime, our ExoGemS survey will allow us to continue investigating the atmospheres of dozens of exoplanets — many of which have never been characterised — from right here on Earth. There’s no doubt that WASP-76b’s weird, wild atmosphere is just the beginning of what we’re going to uncover.

See the full article here .


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The The University of Toronto (CA) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen’s Park. It was founded by royal charter in 1827 as King’s College, the oldest university in the province of Ontario.

Originally controlled by the Church of England, the university assumed its present name in 1850 upon becoming a secular institution.

As a collegiate university, it comprises eleven colleges each with substantial autonomy on financial and institutional affairs and significant differences in character and history. The university also operates two satellite campuses located in Scarborough and Mississauga.

University of Toronto has evolved into Canada’s leading institution of learning, discovery and knowledge creation. We are proud to be one of the world’s top research-intensive universities, driven to invent and innovate.

Our students have the opportunity to learn from and work with preeminent thought leaders through our multidisciplinary network of teaching and research faculty, alumni and partners.

The ideas, innovations and actions of more than 560,000 graduates continue to have a positive impact on the world.

Academically, the University of Toronto is noted for movements and curricula in literary criticism and communication theory, known collectively as the Toronto School.

The university was the birthplace of insulin and stem cell research, and was the site of the first electron microscope in North America; the identification of the first black hole Cygnus X-1; multi-touch technology, and the development of the theory of NP-completeness.

The university was one of several universities involved in early research of deep learning. It receives the most annual scientific research funding of any Canadian university and is one of two members of the Association of American Universities (US) outside the United States, the other being McGill(CA).

The Varsity Blues are the athletic teams that represent the university in intercollegiate league matches, with ties to gridiron football, rowing and ice hockey. The earliest recorded instance of gridiron football occurred at University of Toronto’s University College in November 1861.

The university’s Hart House is an early example of the North American student centre, simultaneously serving cultural, intellectual, and recreational interests within its large Gothic-revival complex.

The University of Toronto has educated three Governors General of Canada, four Prime Ministers of Canada, three foreign leaders, and fourteen Justices of the Supreme Court. As of March 2019, ten Nobel laureates, five Turing Award winners, 94 Rhodes Scholars, and one Fields Medalist have been affiliated with the university.

Early history

The founding of a colonial college had long been the desire of John Graves Simcoe, the first Lieutenant-Governor of Upper Canada and founder of York, the colonial capital. As an University of Oxford (UK)-educated military commander who had fought in the American Revolutionary War, Simcoe believed a college was needed to counter the spread of republicanism from the United States. The Upper Canada Executive Committee recommended in 1798 that a college be established in York.

On March 15, 1827, a royal charter was formally issued by King George IV, proclaiming “from this time one College, with the style and privileges of a University … for the education of youth in the principles of the Christian Religion, and for their instruction in the various branches of Science and Literature … to continue for ever, to be called King’s College.” The granting of the charter was largely the result of intense lobbying by John Strachan, the influential Anglican Bishop of Toronto who took office as the college’s first president. The original three-storey Greek Revival school building was built on the present site of Queen’s Park.

Under Strachan’s stewardship, King’s College was a religious institution closely aligned with the Church of England and the British colonial elite, known as the Family Compact. Reformist politicians opposed the clergy’s control over colonial institutions and fought to have the college secularized. In 1849, after a lengthy and heated debate, the newly elected responsible government of the Province of Canada voted to rename King’s College as the University of Toronto and severed the school’s ties with the church. Having anticipated this decision, the enraged Strachan had resigned a year earlier to open Trinity College as a private Anglican seminary. University College was created as the nondenominational teaching branch of the University of Toronto. During the American Civil War the threat of Union blockade on British North America prompted the creation of the University Rifle Corps which saw battle in resisting the Fenian raids on the Niagara border in 1866. The Corps was part of the Reserve Militia lead by Professor Henry Croft.

Established in 1878, the School of Practical Science was the precursor to the Faculty of Applied Science and Engineering which has been nicknamed Skule since its earliest days. While the Faculty of Medicine opened in 1843 medical teaching was conducted by proprietary schools from 1853 until 1887 when the faculty absorbed the Toronto School of Medicine. Meanwhile the university continued to set examinations and confer medical degrees. The university opened the Faculty of Law in 1887, followed by the Faculty of Dentistry in 1888 when the Royal College of Dental Surgeons became an affiliate. Women were first admitted to the university in 1884.

A devastating fire in 1890 gutted the interior of University College and destroyed 33,000 volumes from the library but the university restored the building and replenished its library within two years. Over the next two decades a collegiate system took shape as the university arranged federation with several ecclesiastical colleges including Strachan’s Trinity College in 1904. The university operated the Royal Conservatory of Music from 1896 to 1991 and the Royal Ontario Museum from 1912 to 1968; both still retain close ties with the university as independent institutions. The University of Toronto Press was founded in 1901 as Canada’s first academic publishing house. The Faculty of Forestry founded in 1907 with Bernhard Fernow as dean was Canada’s first university faculty devoted to forest science. In 1910, the Faculty of Education opened its laboratory school, the University of Toronto Schools.

World wars and post-war years

The First and Second World Wars curtailed some university activities as undergraduate and graduate men eagerly enlisted. Intercollegiate athletic competitions and the Hart House Debates were suspended although exhibition and interfaculty games were still held. The David Dunlap Observatory in Richmond Hill opened in 1935 followed by the University of Toronto Institute for Aerospace Studies in 1949. The university opened satellite campuses in Scarborough in 1964 and in Mississauga in 1967. The university’s former affiliated schools at the Ontario Agricultural College and Glendon Hall became fully independent of the University of Toronto and became part of University of Guelph (CA) in 1964 and York University (CA) in 1965 respectively. Beginning in the 1980s reductions in government funding prompted more rigorous fundraising efforts.

Since 2000

In 2000 Kin-Yip Chun was reinstated as a professor of the university after he launched an unsuccessful lawsuit against the university alleging racial discrimination. In 2017 a human rights application was filed against the University by one of its students for allegedly delaying the investigation of sexual assault and being dismissive of their concerns. In 2018 the university cleared one of its professors of allegations of discrimination and antisemitism in an internal investigation after a complaint was filed by one of its students.

The University of Toronto was the first Canadian university to amass a financial endowment greater than c. $1 billion in 2007. On September 24, 2020 the university announced a $250 million gift to the Faculty of Medicine from businessman and philanthropist James C. Temerty- the largest single philanthropic donation in Canadian history. This broke the previous record for the school set in 2019 when Gerry Schwartz and Heather Reisman jointly donated $100 million for the creation of a 750,000-square foot innovation and artificial intelligence centre.


Since 1926 the University of Toronto has been a member of the Association of American Universities (US) a consortium of the leading North American research universities. The university manages by far the largest annual research budget of any university in Canada with sponsored direct-cost expenditures of $878 million in 2010. In 2018 the University of Toronto was named the top research university in Canada by Research Infosource with a sponsored research income (external sources of funding) of $1,147.584 million in 2017. In the same year the university’s faculty averaged a sponsored research income of $428,200 while graduate students averaged a sponsored research income of $63,700. The federal government was the largest source of funding with grants from the Canadian Institutes of Health Research; the Natural Sciences and Engineering Research Council; and the Social Sciences and Humanities Research Council amounting to about one-third of the research budget. About eight percent of research funding came from corporations- mostly in the healthcare industry.

The first practical electron microscope was built by the physics department in 1938. During World War II the university developed the G-suit- a life-saving garment worn by Allied fighter plane pilots later adopted for use by astronauts.Development of the infrared chemiluminescence technique improved analyses of energy behaviours in chemical reactions. In 1963 the asteroid 2104 Toronto was discovered in the David Dunlap Observatory (CA) in Richmond Hill and is named after the university. In 1972 studies on Cygnus X-1 led to the publication of the first observational evidence proving the existence of black holes. Toronto astronomers have also discovered the Uranian moons of Caliban and Sycorax; the dwarf galaxies of Andromeda I, II and III; and the supernova SN 1987A. A pioneer in computing technology the university designed and built UTEC- one of the world’s first operational computers- and later purchased Ferut- the second commercial computer after UNIVAC I. Multi-touch technology was developed at Toronto with applications ranging from handheld devices to collaboration walls. The AeroVelo Atlas which won the Igor I. Sikorsky Human Powered Helicopter Competition in 2013 was developed by the university’s team of students and graduates and was tested in Vaughan.

The discovery of insulin at the University of Toronto in 1921 is considered among the most significant events in the history of medicine. The stem cell was discovered at the university in 1963 forming the basis for bone marrow transplantation and all subsequent research on adult and embryonic stem cells. This was the first of many findings at Toronto relating to stem cells including the identification of pancreatic and retinal stem cells. The cancer stem cell was first identified in 1997 by Toronto researchers who have since found stem cell associations in leukemia; brain tumors; and colorectal cancer. Medical inventions developed at Toronto include the glycaemic index; the infant cereal Pablum; the use of protective hypothermia in open heart surgery; and the first artificial cardiac pacemaker. The first successful single-lung transplant was performed at Toronto in 1981 followed by the first nerve transplant in 1988; and the first double-lung transplant in 1989. Researchers identified the maturation promoting factor that regulates cell division and discovered the T-cell receptor which triggers responses of the immune system. The university is credited with isolating the genes that cause Fanconi anemia; cystic fibrosis; and early-onset Alzheimer’s disease among numerous other diseases. Between 1914 and 1972 the university operated the Connaught Medical Research Laboratories- now part of the pharmaceutical corporation Sanofi-Aventis. Among the research conducted at the laboratory was the development of gel electrophoresis.

The University of Toronto is the primary research presence that supports one of the world’s largest concentrations of biotechnology firms. More than 5,000 principal investigators reside within 2 kilometres (1.2 mi) from the university grounds in Toronto’s Discovery District conducting $1 billion of medical research annually. MaRS Discovery District is a research park that serves commercial enterprises and the university’s technology transfer ventures. In 2008, the university disclosed 159 inventions and had 114 active start-up companies. Its SciNet Consortium operates the most powerful supercomputer in Canada.