Astrophysics

For a billion years, Earth's day lasted just 19.5 hours – a new study reveals why

siddiq22 — Thu, 13 Jul 2023 16:54:12 +0000

For a billion years, Earth's day lasted just 19.5 hours – a new study reveals why

siddiq22 Thu, 07/13/2023 - 12:54

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Without the sun’s pull on the Earth’s atmosphere, our day would be 60 hours long (photo by dima_zel/Getty images)

Chris Sasaki

Topic

Breaking Research

Physical and Environmental Sciences

Astronomy

Astrophysics

Canadian Institute for Theoretical Astrophysics

Climate Change

Faculty of Arts & Science

Physics

Research & Innovation

U of T Scarborough

Subheadline

An atmospheric tide driven by the sun countered the effect of the moon, astrophysicists say

A team of astrophysicists from the ��Ƶ has revealed how the slow and steady lengthening of Earth’s day caused by the tidal pull of the moon was halted for over a billion years.

They show that from approximately two billion years ago until 600 million years ago, an atmospheric tide driven by the sun countered the effect of the moon, keeping Earth’s rotational rate steady and the length of day at a constant 19.5 hours.

Without this billion-year pause in the slowing of our planet’s rotation, our current 24-hour day would stretch to over 60 hours.

Drawing on geological evidence and using atmospheric research tools, the scientists show that the tidal stalemate between the sun and moon resulted from the incidental but consequential link between the atmosphere’s temperature and Earth’s rotational rate.

The study was published in the journal Science Advances.

The paper’s authors include Professor Norman Murray, a theoretical astrophysicist with the Faculty of Arts & Science’s Canadian Institute for Theoretical Astrophysics (CITA); graduate student Hanbo Wu, with CITA and the department of physics; Kristen Menou, associate professor in the David A. Dunlap department of astronomy and astrophysics and the department of physical and environmental sciences at U of T Scarborough; Jeremy Leconte, a CNRS researcher at the Laboratoire d’astrophysique de Bordeaux and a former CITA postdoctoral fellow; and Christopher Lee, assistant professor in the department of physics.

Murray and his collaborators relied on geologic evidence in their study, like these samples from a tidal estuary that reveal the cycle of spring and neap tides. Thick bands correspond to spring tides, and thin bands to neap tides (image by G.E. Williams)

When the moon first formed some 4.5 billion years ago, the day was less than 10 hours long. But since then, the moon’s gravitational pull on the Earth has been slowing our planet’s rotation, resulting in an increasingly longer day. Today, it continues to lengthen at a rate of some 1.7 milliseconds every century.

The moon slows the planet’s rotation by pulling on Earth’s oceans, creating tidal bulges on opposite sides of the planet that we experience as high and low tides. The gravitational pull of the moon on those bulges, plus the friction between the tides and the ocean floor, acts like a brake on our spinning planet.

“Sunlight also produces an atmospheric tide with the same type of bulges,” says Murray. “The sun's gravity pulls on these atmospheric bulges, producing a torque on the Earth. But instead of slowing down Earth’s rotation like the moon, it speeds it up.”

For most of Earth’s geological history, the lunar tides have overpowered the solar tides by about a factor of ten – hence the Earth’s slowing rotational speed and lengthening days.

But some two billion years ago, the atmospheric bulges were larger because the atmosphere was warmer and because its natural resonance – the frequency at which waves move through it – matched the length of day.

The atmosphere, like a bell, resonates at a frequency determined by various factors, including temperature. In other words, waves – like those generated by the enormous eruption of the volcano Krakatoa in Indonesia in 1883 – travel through it at a velocity determined by its temperature. The same principle explains why a bell always produces the same note if its temperature is constant.

Throughout most of Earth’s history that atmospheric resonance has been out of sync with the planet’s rotational rate. Today, each of the two atmospheric “high tides” take 22.8 hours to travel around the world. Since that resonance and Earth’s 24-hour rotational period are out of sync, the atmospheric tide is relatively small.

But during the billion-year period under study, the atmosphere was warmer and resonated with a period of about 10 hours. Also, at the advent of that epoch, Earth’s rotation – slowed by the moon – reached 20 hours.

When the atmospheric resonance and length of day became even factors (ten and 20), the atmospheric tide was reinforced, the bulges became larger and the sun’s tidal pull became strong enough to counter the lunar tide.

“It’s like pushing a child on a swing,” Murray says.

“If your push and the period of the swing are out of sync, it’s not going to go very high. But, if they’re in sync and you’re pushing just as the swing stops at one end of its travel, the push will add to the momentum of the swing and it will go further and higher. That’s what happened with the atmospheric resonance and tide.”

Along with geological evidence, Murray and his colleagues achieved their result using global atmospheric circulation models (GCMs) to predict the atmosphere’s temperature during this period. The GCMs are the same models used by climatologists to study global warming. Murray says the fact they worked so well in the team’s research is a timely lesson.

“I've talked to people who are climate-change skeptics who don't believe in the global circulation models that are telling us we’re in a climate crisis,” he says. “And I tell them: We used these global circulation models in our research, and they got it right. They work.”

Despite its remoteness in geological history, the result adds additional perspective to the climate crisis. Because the atmospheric resonance changes with temperature, Murray points out that our current warming atmosphere could have consequences in this tidal imbalance.

“As we increase Earth's temperature with global warming, we’re also making the resonant frequency move higher – we’re moving our atmosphere farther away from resonance. As a result, there's less torque from the sun and therefore the length the day is going to get longer – sooner than it would otherwise.”

First space images captured by balloon-borne telescope

siddiq22 — Fri, 21 Apr 2023 13:34:16 +0000

First space images captured by balloon-borne telescope

siddiq22 Fri, 04/21/2023 - 09:34

Cutline

A false-colour image of the “Tarantula Nebula” taken in visible and ultraviolet light by the SuperBIT telescope shortly after launch (image courtesy of SuperBIT)

Topic

Breaking Research

Astronomy

Astronomy & Astrophysics

Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty & Staff

Graduate Students

Research

Astronomers have successfully launched a balloon-borne telescope that has begun capturing images of the universe on its first flight above the Earth’s atmosphere.

The Super Pressure Balloon-Borne Imaging Telescope (SuperBIT) was flown to the edge of space by a helium-filled NASA scientific balloon the size of a football stadium. There, it will help researchers investigate the mystery of dark matter.

SuperBIT has already taken its first images on this flight, showing the “Tarantula Nebula” – a bright cluster of gas and dust in a galaxy neighbourhood near our Milky Way – and the collision between the two galaxies NGC 4038 and NGC 4039, known as “the Antennae.”

SuperBIT is a collaboration between the ��Ƶ, Princeton University, Durham University and NASA.

“A dedicated team of students developing one of the world’s great telescopes – it’s inspiring,” says Barth Netterfield, a professor in U of T's David A. Dunlap department of astronomy and astrophysics and the department of physics in the Faculty of Arts & Science, and an associate at the Dunlap Institute for Astronomy and Astrophysics.

“After a decade of tremendous effort, we are getting these exquisite images with a wide range of science goals, which will help us to better understand the universe.”

A false-colour image taken by the SuperBIT telescope shows of a pair of galaxies smashing into each other (image courtesy of SuperBIT)

The balloon aunched from Wānaka, New Zealand earlier this week, following a two-year delay due to the COVID pandemic.

Carried by seasonally stable winds for about three months, SuperBIT will circumnavigate the southern hemisphere several times – imaging the sky all night, then using solar panels to recharge its batteries during the day.

SuperBIT flies at an altitude of 33.5 kilometres, above 99.5 per cent of the Earth’s atmosphere. It takes high-resolution images like those from the Hubble Space Telescope, but with a much wider field of view.

The scientific goal for the first flight is to measure the properties of dark matter, a heavy but invisible type of material.

SuperBIT will test whether dark-matter particles can bounce off each other, by mapping the dark matter around clusters of galaxies that are colliding with neighbouring galaxy clusters.

The SuperBIT telescope in New Zealand prior to the launch (photo courtesy of Columbia Scientific Balloon Facility)

Various theories suggest that some dark matter might either slow down, spread out, or get chipped off during a collision.

Although dark matter is invisible, SuperBIT will map where it is by the way it bends passing rays of light – a technique known as gravitational lensing.

While telescopes on the ground must squint through the Earth’s atmosphere – meaning their view can become blurred – space-based telescopes get a clear view of the light that has travelled billions of years from the distant universe.

Members of the SuperBIT team prepare for a flight test (photo courtesy of SuperBIT)

SuperBIT is the first balloon-borne telescope capable of taking wide-field images – its sharpness of vision is not affected by the atmosphere, but only by the laws of optics.

During its final test flight in 2019, SuperBIT demonstrated extraordinary pointing stability.

“Imagine you’re trying to thread a needle that’s 2.5 kilometres away – so roughly 30 city blocks,” explains Emaad Paracha, a PhD candidate in the department of physics.

“SuperBIT has the ability to point to the exact spot you’d need that needle to be thread, while keeping that thread from touching the sides of the needle for up to 60 minutes.”

SuperBIT cost about US$5 million – almost 1,000 times less than an equivalent satellite. Not only is helium cheaper than rocket fuel, but the ability of SuperBIT to return to Earth via parachute meant the team could tweak its design over several test flights.

“A successful SuperBIT launch paves the way to a future in which individual academic institutions are able to design, develop and operate world-class space instruments at a low cost, while also providing the training opportunity for instrument development and data analysis for the students,” says Ajay Gill, a PhD candidate at the David A. Dunlap department of astronomy and astrophysics and the Dunlap Institute.

SuperBIT can also be upgraded on a regular basis. For example, the development team buys a new camera shortly before each launch, because modern detectors are improving so rapidly.

The team already has funding to upgrade SuperBIT’s 0.5-metre telescope to 1.6 metres, which would boost light gathering power tenfold, with a wider-angle lens and more megapixels.

The relatively cheap cost may even make it possible for a fleet of balloon-borne telescopes to offer time to astronomers around the world. Interested members of the public can track SuperBIT's flight status on NASA's website.

The mission was funded by NASA, the Canadian Space Agency, the Royal Society and U of T's Dunlap Institute for Astronomy and Astrophysics.

With notes from Meaghan MacSween

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Leighton Kitson

U of T in focus: The year in pictures

geoff.vendeville — Wed, 19 Dec 2018 05:00:00 +0000

U of T in focus: The year in pictures

geoff.vendeville Wed, 12/19/2018 - 00:00

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Mason Godkewitsch, 8, makes shadow puppets on the walls of the “cell cave” in the student lounge in the McLennan building on the downtown Toronto campus (photo by Geoffrey Vendeville)

Topic

Canada Research Chairs

Faculty & Staff

Faculty of Applied Science & Engineering

Research & Innovation

STEM

U of T Mississauga

U of T Scarborough

Undergraduate Students

University College

In the lab, classrooms and at a variety of events on the three ��Ƶ campuses, U of T News photographers captured moments that made this year special.

Staff photographer Nick Iwanyshyn selected some of the highlights of 2018.

Axel Guenther, scientific director of the Centre for Microfluidic Systems, inspects microfluidic devices in a cleanroom. This fall, U of T partnered with Canada’s National Research Council to create a national innovation hub focused on microfluidics (photo by Nick Iwanyshyn)

Students line up before making a grand entrance at the second student-led Black graduation ceremony in June at Hart House. In 2017, U of T became the first Canadian university to host a Black graduation (photo by Geoffrey Vendeville)

Foreign Affairs Minister Chrystia Freeland looks on during a service of remembrance at the ��Ƶ's downtown campus (photo by Nick Iwanyshyn)

Alán Aspuru-Guzik, who came to U of T from Harvard University to become a Canada 150 Research Chair, delivered the keynote address at the ��Ƶ-Tsinghua University Entrepreneurship and Innovation Forum in May (photo by Chris Sorensen)

Elspeth Arbow, an undergraduate student with cystic fibrosis recovering from her second double-lung transplant, gets ready for physiotherapy at Toronto General Hospital on May 4 (photo by Geoffrey Vendeville)

Wearing matching maple leaf socks, former U.S. vice-president Al Gore and former Google CEO Eric Schmidt chat on the main stage at the Elevate technology conference in Toronto, on Sept. 26 (photo by Chris Sorensen)

Your mind isn't playing tricks on you. Students go up the stairs at U of T Scarborough (photo by Nick Iwanyshyn)

Kirsty Duncan, minister of science and sport, watches a demonstration during a Nov. 13 announcement about new and renewed chairs in the Canada Research Chairs program, including 21 at U of T (photo by Nick Iwanyshyn)

Cranes in the colours of the rainbow hang from a window at Hart House's reading room in June to mark Pride (photo by Romi Levine)

Students gather to study and chat at U of T Mississauga (photo by Nick Iwanyshyn)

Enakshi Shah, who earned a bachelor's degree in chemical engineering at U of T, found there were lots of opportunities after graduating (photo by Nick Iwanyshyn)

A girl adds to a poster about what it means to be a woman in science, technology, engineering and math (STEM) at Science Rendezvous on May 12 (photo by Geoffrey Vendeville).

Hundreds of people in a rainbow of colours filled the Goldring Centre for High Performance Sport at the ��Ƶ for the Indigenous Studies Students' Union's powwow on March 11 (photo by Laura Pedersen)

For Remembrance Day and the 100^th anniversary of the armistice ending the First World War, U of T News staff photographer Nick Iwanyshyn juxtaposed archival campus photos with present-day pictures at the same location. Above, a Sopwith Camel plane appears in front of University College in 1918 (photo illustration includes a U of T Archives photograph)

Members of the U of T community gather outside of University College on Oct. 30 for a vigil for victims of the attack on the Tree of Life synagogue in Pittsburgh (photo by Romi Levine)

Astrophysicist Matt Russo makes music using the movements of objects in space. The music was featured in Our Musical Universe, an audio-focused planetarium show that debuted at U of T in January (photo by Romi Levine)

Drummers welcome delegates during a Spiritual Opening Ceremony for the Parliament of the World’s Religions around the Sacred Fire in Olympic Park, on Nov. 2 (photo by Nick Iwanyshyn)

Rose Patten, centre, U of T's 34th chancellor, was installed in a ceremony in November (photo by Nick Iwanyshyn)

At the 25th annual Bring Our Children to Work Day on April 26, kids got to see a soda geyser made of Mentos and cola spraying 12 feet above the courtyard near Lash Miller Chemical Laboratories (photo by Geoffrey Vendeville)

Molly Shoichet on the importance of creativity, imagination in research

noreen.rasbach — Tue, 06 Mar 2018 05:00:00 +0000

Molly Shoichet on the importance of creativity, imagination in research

noreen.rasbach Tue, 03/06/2018 - 00:00

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"I think what we need to do more of in Canada is celebrate science and celebrate discovery and encourage curiosity," says U of T's Molly Shoichet, Ontario's chief scientist (photo by Roberta Baker)

Jennifer Robinson

Topic

Our Community

Astrophysics

Faculty of Applied Science & Engineering

Faculty of Law

Indigenous

Molly Shoichet

Regenerative Medicine

Research & Innovation

Three top scholars – an astrophysicist, an Indigenous legal rights expert and a biomedical engineer – will talk about the importance of creativity and imagination in the pursuit of world-changing research at a special anniversary event tonight for one of the most prestigious awards in Canada.

All three Killam Prize winners will speak at Innis Town Hall Theatre. Tickets are free and are available by registering here.

The event, hosted by the Canada Council for the Arts and moderated by Paul Kennedy, host of CBC Radio's Ideas, features:

John Borrows, Canada Research Chair in Indigenous Law at the University of Victoria Faculty of Law and former professor in the Faculty of Law at the ��Ƶ
Victoria Kaspi, Canada Research Chair in Observational Astrophysics and director of the McGill Space Institute, McGill University
Molly Shoichet, Ontario’s chief scientist, Canada Research Chair in Tissue Engineering and professor in U of T’s Faculty of Applied Science & Engineering’s department of chemical engineering and applied chemistry and the Institute for Biomaterials & Biomedical Engineering.

To get an idea of what the evening may hold, U of T News caught up with Shoichet, a globally recognized leader in stem cell transplantation and regenerative medicine, ahead of her talk.

Why is creativity and imagination important in your research?

We’re trying to solve problems that no one has been able to solve. If you want to try and solve a really big problem, you have to take a different approach from what other people have done – that requires creativity and imagination.

For example, we’re trying to get the brain to regenerate. We know the brain has the capacity to do this but no one’s really been able to figure out how to do that after a traumatic injury like a stroke. So how can we get the brain to repair itself? What molecules can we deliver to it or what cells can we transplant to get the brain to repair itself after a stroke?

I’ve heard there’s been about a thousand failed clinical trials in strokes. That’s a lot of really smart people not being successful. If we try to do the same thing, we’re just going to continue to fail.

What impact is your work and your field having on the world?

I look at research as the core to invention, innovation and commercialization. If we don’t do that research, we’re not going to have those inventions, the innovation, the commercialization, and you’re not going to have impact on human health.

Have we impacted human health so far? No. But that is a major driver for what we do and a major driver for the creativity we talked about before.

In our lab, we use innovation in chemistry and engineering to solve problems and answer questions in biology and medicine. We have invented new materials, we have licensed those materials to companies, or used our inventions as the founding technology to start companies, and this is an active part of what we do.

Recently we started a company that focuses on post-surgical pain. We want to use some of our inventions to better manage pain for these patients. It’s a very exciting time to take that invention and that commercial opportunity to make a difference in people’s quality of life.

Conference brings international group of astrophysicists to U of T

ullahnor — Wed, 16 Aug 2017 19:41:28 +0000

Conference brings international group of astrophysicists to U of T

ullahnor Wed, 08/16/2017 - 15:41

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Assistant Professor Hanno Rein (left) and postdoctoral fellow Daniel Tamayo (right) of U of T Scarborough’s Centre for Planetary Science are hosting a three-day conference bringing together astrophysicists from around the world (photo by Ken Jones)

Don Campbell

Author legacy

Don Campbell

Topic

When it comes to figuring out what’s going on in distant solar systems, astrophysicists rely on a powerful set of mathematical tools called numerical integration methods – algorithms that calculate the motion of objects in space.

But even relatively small errors quickly add up with these calculations, especially when the models are run over the long-time scales involved in the life of planetary systems. Researchers have found that high precision comes at a cost, namely efficiency.

Assistant Professor Hanno Rein and postdoctoral researcher Daniel Tamayo hosted a three-day conference at U of T Scarborough’s Centre for Planetary Science this week, bringing together international experts who are using integration methods.

“It’s exciting to bring in so many international experts,” Rein said, adding that many of those who attended are pioneers in the field. "For example, we made many references to the Wisdom-Holman Integrator. Well, Professor Jack Wisdom [of planetary sciences at MIT] who helped develop it is here in attendance, so that makes it very exciting.”

Tamayo said the conference is a reflection of the quality of research taking place at the Centre for Planetary Science.

“This definitely shows that Hanno’s research group has reached the international stature where it's able to attract the researchers who really laid the groundwork in this field,” he said. “It’s also great that U of T Scarborough has become one of those centres for this line of research.”

Rein and Tamayo spoke to writer Don Campbell about numerical integrations and why they're so critical for current and future planetary science research.

What on earth are numerical integration methods?

Hanno Rein: As astrophysicists, we use algorithms to calculate the motion of celestial objects such as stars, planets and moons as efficiently and accurately as we can.

This is a very old topic in general dating back to the time of Isaac Newton. Famous mathematicians ever since have worked on it. But there’s been a renaissance over the last 50 years when computers first started being able to do these calculations efficiently. Especially over the last few years, there’s been growth in the field because of all the planets discovered outside of our own solar system.

Where scientists in the past could only look at our own solar system exclusively when doing these calculations, we can now take the methods they’ve developed and apply them to this entirely new field of exoplanets that we’re a part of.

A significant part of the conference is looking at unresolved problems in these methods. Why is that important?

Daniel Tamayo: Planetary systems live for billions to hundreds of billions of orbits, which is an incredibly long period of time, and any tiny mistake will make an entire solution invalid. In some sense, the numerical algorithms that we’re working with are like the precision experiments that people studying physics use to measure something intricate like the gravitational constant. There are plenty of things that can go wrong to mess up your measurements, so you need to ensure a high level of precision.

We’re aiming to not just sort out how these types of precision errors can be avoided but also come up with a smart way that causes the errors to cancel each other out. We also hope to come up with creative ways to ensure consistency so we can trust the solutions we end up with.

What are some examples of where these methods are applied?

Hanno Rein: With many exoplanets being discovered, one thing that is hard to find is their parameters – things like mass, diameter and orbital frequency. One challenge is that there are many different parameters that can produce similar results when observed, so we’re trying to find ways that ensure we know which parameters are the most probable.

Since we need to run these numerical experiments many times, it’s important they’re as efficient as possible so when we use them to determine the parameters of other planets we can do so with certainty.

Peering deep into the stellar nursery of the Orion Nebula: U of T astronomers part of team

ullahnor — Thu, 15 Jun 2017 21:01:27 +0000

Peering deep into the stellar nursery of the Orion Nebula: U of T astronomers part of team

ullahnor Thu, 06/15/2017 - 17:01

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In this composite image, the filament of ammonia molecules appears red and Orion Nebula gas appears blue (image courtesy of R. Friesen, Dunlap Institute; J. Pineda, MPE; GBO/AUI/NSF)

Chris Sasaki

Author legacy

Chris Sasaki

Topic

Astronomers have released an image of a vast filament of star-forming gas, 1,200 light-years away, in the stellar nursery of the Orion Nebula.

The image shows ammonia molecules within a 50-light-year long filament detected through radio observations made with the Robert C. Byrd Green Bank Telescope in West Virginia. It accompanies the first release of results from a research collaboration published in the Astrophysical Journal Supplement.

A team of researchers are collaborating on a survey of all the major, nearby star-forming regions in the northern half of the Gould Belt – a ring of young stars and gas clouds that circles the entire sky and runs through the constellation Orion. The researchers hope the survey will eventually provide a clearer picture over a larger portion of the sky of the temperatures and motions of gas within these dynamic stellar nurseries.

“We still don’t understand in detail how large clouds of gas in our galaxy collapse to form new stars,” says Rachel Friesen, one of the collaboration’s co-principal researchers who until recently was a fellow at U of T's Dunlap Institute for Astronomy & Astrophysics.

“But ammonia is an excellent tracer of dense, star-forming gas, and these large ammonia maps will allow us to track the motions and temperature of the densest gas. This is critical to assessing whether gas clouds and filaments are stable, or are undergoing collapse on their way to forming new stars.”

The image is combined with an image of the Orion Nebula – an object familiar to amateur and professional astronomers alike – taken with NASA’s wide-field infrared survey explore (WISE) telescope.

The collaboration’s other co-principal investigator is Jaime Pineda, from the Max Planck Institute for Extraterrestrial Physics. The team also includes Associate Professor Chris Matzner and graduate student Ayushi Singh from the ��Ƶ’s department of astronomy & astrophysics, and the Canadian Institute for Theoretical Astrophysics Professor Peter Martin, who helped found the Dunlap Institute.

Three U of T scholars receive Killam awards

ullahnor — Tue, 02 May 2017 15:08:01 +0000

Three U of T scholars receive Killam awards

ullahnor Tue, 05/02/2017 - 11:08

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Professors Thomas Hurka (left) and Molly Shoichet (centre) each received the $100,000 Killam Prize for their research. Astrophysics Professor Roberto Abraham (right) received a two-year Killam Research Fellowship (composite by Geoffrey Vendeville)

Jennifer Robinson

Author legacy

Jennifer Robinson

Topic

Regenerative Medicine

Astrophysics

Faculty of Applied Science & Engineering

Faculty of Arts & Science

A world-renowned philosopher, a regenerative medicine leader and an astrophysicist are the three U of T scholars recognized by the Canada Council for the Arts’ prestigious Killam Program this year.

University Professors Thomas Hurka and Molly Shoichet are each receiving the $100,000 Killam Prize for their leading research in the fields of philosophy and engineering.

This is the second year in a row that a female U of T researcher has won the Killam Prize in engineering. Last year, bioremediation pioneer Professor Elizabeth Edwards won.

Hurka, the Chancellor Henry N. R. Jackman Distinguished Professor of Philosophical Studies at U of T, is the author of many works in moral and political philosophy, including Perfectionism, his groundbreaking book Virtue, Vice, and Value and his 2011 book, The Best Things in Life: A Guide to What Really Matters. Much of his research has concerned the human good or which states and activities make our lives most desirable.

“The Killam Prize is an immense honour, especially since it's for the whole body of one's scholarly work,” said Hurka. “We all try to contribute to our disciplines, and the prize is a gratifying validation that, to at least some extent, I've done that.”

Galactic game-changer receives Sloan Fellowship

sgupta — Tue, 23 Feb 2016 14:50:50 +0000

Galactic game-changer receives Sloan Fellowship sgupta Tue, 02/23/2016 - 09:50

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Jo Bovy is the first researcher to measure the motion of the Sun, using information from disk stars beyond our immediate stellar neighbourhood (photo by Diana Tyszko)

Peter McMahon

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Peter McMahon

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Faculty of Arts & Science

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Jo Bovy of astronomy & astrophysics, one of two U of T scientists honoured

Jo Bovy looks out his office window towards the billions of stars of the Milky Way. It's daytime, so he can’t actually see those stars. At night, or even out in the pristine blackness of space, our galaxy is so vast that most of it is concealed over great distance.

But for Bovy, it’s the distant, sometimes invisible aspects of our galaxy that fascinate him the most.

“A lot of the most exciting new measurements being made in physics today are in the night sky,” says Bovy, who has received a prestigious Sloan Fellowship to further his investigations into the structure, formation and evolution of the Milky Way.

Along with neuroscientist Christopher Honey, Bovy is one of two U of T Sloan Fellowship recipients this year – both in the Faculty of Arts & Science. The Sloan Fellowships are awarded to 126 non-tenured scholars and scientists around the world annually. Sloan Fellows are expected to be at an early stage of their careers but with a strong body of independent research accomplishments.

Among other achievements, Bovy was instrumental in making the first-ever detailed measurements of the chemical structure of the Milky Way’s disk – the relatively flat arrangement of spiral arms, spurs and other collections of gas, dust and stars beyond the glowing bulge of our galaxy's central nucleus.

“Galaxies are just such huge, majestic structures.... It's amazing to learn how they work over cosmic time,” says Bovy, who holds a Canada Research Chair in Galactic Astrophysics.

To map out the chemistry of the Milky Way, Bovy used data from the New-Mexico-based Apache Point Observatory Galactic Evolution Experiment (APOGEE-1) survey for which he is the Science Working Group Chair.

APOGEE uses high-resolution infrared spectroscopy to look past the dust that obscures parts of our galaxy far from the Solar System, revealing the chemistry of tens of thousands of distant stars in detail that hasn't been possible until the last few years.

“After a single night of observing, we can find out more than we used to in years,” says Bovy.

Using data from another instrument at Apache Point, Bovy has also been able to show that the vertical structure of the Milky Way’s disk is different than what researchers had previously thought.

By separating populations of stars in the disk by their chemical signatures, Bovy was able to show that most of our galaxy’s mass is distributed throughout thin and thick parts of the galactic disk – a departure from the previous theory that most of the structure of the Milky Way’s disk is in a thin part, with a much smaller amount in a single thick component.

Bovy has even become the first researcher to measure the motion of our own star, the Sun, using information from disk stars beyond our immediate stellar neighbourhood, as the stars travel around our galactic nucleus.

By doing so, he discovered that the Sun's orbit around our galaxy is twice as ellipse-shaped as scientists thought. Bovy and team also found that the Sun is inching ahead of nearby stars in its orbit nearly twice as fast as was previously estimated.

While the average speed of the stars moving around the centre of our galaxy is about 220 km/second, Bovy found that the Sun is actually moving about 25 km/s faster – like a person walking down a moving walkway at an airport, adding their own stride to the speed of the walkway.

Over the next two years, Bovy will use his $50,000 Sloan grant to study data from the European Space Agency's Gaia spacecraft, which is creating a 3D map of the locations and motions of roughly 1 billion objects throughout the Milky Way.

Bovy intends to use the velocities of distant stars mapped out by Gaia to figure out how the mass of stars is distributed in the galactic disk, as well as searching for insights into what scientists call the dark matter halo, a hypothetical part of our galaxy that can't be seen but contains 20 times as much mass as all of the stars in the Milky Way.

Bovy says his dream discovery would be to determine how dark matter is distributed on very small scales: “If [that matter] is cold, there should be all these tiny blobs floating around in the Milky Way,” he says. “You wouldn't be able to see them, but I'd love to figure out if it exists that way.”

“I'd like to finish that well before retirement,” Bovy says, chuckling. “In the next 10 years or so would be nice.”

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U of T astrophysicists offer proof this famous image shows planets forming

sgupta — Tue, 28 Apr 2015 15:59:44 +0000

U of T astrophysicists offer proof this famous image shows planets forming sgupta Tue, 04/28/2015 - 11:59

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This image sparked scientific debate when it was released last year, with researchers arguing over whether newly forming planets were responsible for gaps in the dust and gas swirling around the young star

Don Campbell

Author legacy

Don Campbell

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Breaking Research