Searching for alien worlds

U of T alum Sara Seager presents 2018 Tuzo Wilson Lecture on exoplanets

Searching for alien worlds

In his television series Cosmos: A Personal Voyage, popular astrophysicist Carl Sagan emphasized the importance of exploring other planets to give scientists a better understanding of the rapidly changing environment on Earth.

By comparing our local climates to more extreme examples, he explained that “by exploring other worlds we safeguard this one.”

Sagan spoke those words in 1980, eight years prior to the discovery of the first exoplanet, a planet beyond our solar system. In the three short decades since astrophysicists detected the exoplanet revolving around star Gamma Cephei, the astronomical community has discovered nearly 4,000 more, with nearly 3,000 possible candidates undergoing further study.

Leading the charge is Professor Sara Seager of the Massachusetts Institute of Technology, who presented the 2018 Tuzo Wilson Lecture at the Isabel Bader Theatre on November 20.

The Tuzo Wilson Lectures are an annual event held by the Department of Physics in memory of Professor J. Tuzo Wilson, a pioneer of geophysics at U of T and in Canada and the first Director of the Ontario Science Centre. Since the establishment of the J. Tuzo Wilson Professorship in Geophysics in 1995, the incumbent professor has been annually responsible for delivering the lecture in their inaugural year, and for organizing the lecture in the years that follow.

Seager is a shining example of those who hunt for planets orbiting distant stars. Her work in improving methods of exoplanet detection and her dedicated search for an Earth-like exoplanet has even netted her the moniker of “astrophysical Indiana Jones” by NASA. So it was no surprise that almost all 500 seats in the Isabel Bader Theatre were packed for her presentation, with many U of T astro-enthusiasts jostling to hear her speak on the latest discoveries in the field.

Seager began the lecture with an introduction to what exoplanets are, displaying a number of artistic renditions, before moving into a more detailed explanation of how exactly astronomers detect the distant spheroids. She explained that most exoplanets — 78.1 per cent of them — are detected by the transiting method.

Using the transiting method, astronomers like Seager chart the brightness of several stars over extended periods of time, with regular decreases in light intensity likely explainable by the movement of an exoplanet across our view of the star.

But regular optical telescopes aren’t always suitable for such observations, and Seager continued the lecture by expounding on some of the new tools and instruments that stargazers around the globe will soon be able to take advantage of. In particular, she highlighted the recently-launched Transiting Exoplanet Survey Satellite (TESS).

“TESS is going to find more of these planets orbiting red dwarf stars transiting planets, actually and the goal is to map most of the sky looking at all of the bright M dwarfs stars and any other stars that fall in the field of view as well,” said Seager.

Seager also emphasized how rapidly the field is developing, with some newer ideas in exoplanet astronomy seemingly bordering on science fiction.

An audience favourite, netting hearty laughs, was the Starshot project, which is an ongoing effort to send micro-satellites buoyed by single-square-metre solar sails to nearby stars by shooting lasers at them. If successful, these “starchips” would travel at five per cent the speed of light, and reach Alpha Centauri in roughly 20 years.

While the image of lasers shooting into space to propel tiny satellites may seem ludicrous, Seager was quick to mention that “in exoplanets, the line between what is mainstream science and what is completely crazy is constantly shifting.”

There was a sense of homecoming in her delivery of the lecture, as Seager is a Toronto native and completed her Bachelor of Science with Honours in Math and Physics at U of T before continuing onto a PhD at Harvard University.

As such, her academic career has now looped around, as she was inundated with questions following the lecture from the U of T audience that she was once a part of.

The audience was composed not only of professional academics, but also of astrophiles of every age and background knowledge, inspired to become involved in the hunt for worlds beyond our own.

For those who missed it, the recorded lecture is available on the Department’s YouTube page, UT Physics.

A time-lapse of Supernova 1987A

PhD student Yvette Cendes models the aftermath of the supergiant star

A time-lapse of Supernova 1987A

Yvette Cendes, a PhD student in the Dunlap Institute for Astronomy & Astrophysics, used mathematical modeling to visualize a time-lapse of the aftermath of Supernova 1987A.

Based on existing quantitative data, the time-lapse observes the supernova’s shockwave — a powerful wave that causes a star to explode in space — from 1992–2017.

Since publishing her team’s findings in The Astrophysical Journal, Cendes has delivered several talks about Supernova 1987A.

The significance of the time-lapse

The team’s analyses show that the “expanding remnant” of the supernova is shaped like a three-dimensional torus, or donut, rather than a two-dimensional ring.

Cendes applied statistical and mathematical techniques to the time-lapse to show that the supernova produced a shockwave expanding outward and slamming into debris that ringed the original star before its demise.

As a result of the growing torus punching “through the ring of debris,” the supernova’s shockwave has accelerated, increasing in speed by some one thousand kilometres per second.

The team also found that the shockwave from the supernova models a classic shockwave system.

A principle similar to a shockwave can be seen when a rock creates ripples in a pond. In space, however, a shockwave operates on a much larger magnitude and causes a supernova to explode.

This explosion produces supernova remnants, which are seen in the donut-shape formation of Supernova 1987A.

The origins of Supernova 1987A

U of T astronomer Ian Shelton and telescope operator Oscar Duhalde discovered Supernova 1987A on February 24, 1987. The pair was the first to observe the death of the supergiant star and its resultant explosion from the Las Campanas Observatory in northern Chile.

Despite being 168,000 light-years — or 1.6 quintillion kilometres — away from Earth, Supernova 1987A has been the brightest supernova to appear in our skies since Kepler’s Supernova in 1604.

According to NASA, the supernova “blazed with the power of 100 million suns” for “several months following its discovery.”

While 1.6 quintillion kilometres might seem like a titanic distance, Supernova 1987A is “the closest supernova to us that we’ve observed since the invention of the telescope,” said Cendes in an interview with The Varsity.

This helps to explain Supernova 1987A’s brightness and why it is one of the most studied objects in astronomy.

The aftermath of Supernova 1987A

Under the supervision of U of T professor Bryan Gaensler, Cendes spent nine months analyzing data from 1992 to 2017, collected from a radio telescope called the CSIRO Australia Telescope Compact Array.

Cendes’ initial challenge was learning how to translate the raw radio data from the Compact Array into images, which she eventually presented in her time-lapse.

Since this was her first time using data from the Compact Array, Cendes began by replicating previously-published images that used data from the same telescope.

She then produced her own images by analyzing the datasets used, comparing them to the published images, and refining her technique until her images resembled the published ones.

After becoming proficient in data-to-image translation, Cendes analyzed the 25-year dataset from the radio telescope in full.

While previous researchers had analyzed parts of the dataset, Cendes said that she was “the first person to go back and really see this entire stretch of time.”

A day — or millennium — in the life of a star

PhD candidate Alysa Obertas hosts Life and Death of Stars planetarium show

A day — or millennium — in the life of a star

It is truly a shame that light pollution prevents Torontonians from gazing at the stars because, as Alysa Obertas demonstrates, they are some of the most beautiful objects in all of existence. Admittedly, stars being beautiful isn’t exactly news. But Obertas, a PhD candidate with U of T’s Department of Astronomy & Astrophysics, breathes new life into this tired cliché in the brilliant planetarium show Life and Death of Stars.

Originally created by U of T astrophysicist and Outreach Coordinator of the Department of Mathematics Dr. Ilana MacDonald, the show is presented in the basement planetarium of the Astronomy & Astrophysics Building. Life and Death of Stars opens with a sweeping view of the Toronto skyline, familiarly devoid of stars and overwhelmingly polluted by the glaring city lights. Obertas soon shows us city dwellers what we’ve been missing by transforming a murky screen into a majestic illumination of the skies outside the city.

From there, the audience is brought on a voyage from the surface of our planet into the sprawling grounds of the cosmos. Moving from one celestial object to another, Obertas meticulously explains each astrophysical concept and fundamental law governing the birth, life, and death of stars. Notable curiosities like the red supergiant Betelgeuse and goldmine supernova SN1987A are given special attention, with their unusual traits fully exposed via high-resolution images on-screen, and a comprehensive commentary given by Obertas off-screen.

“One thing I hope audiences take away is that stars aren’t fixed they change and evolve throughout their lifetimes,” wrote Obertas in an email to The Varsity. “Even more incredible is that as stars evolve and eventually end their lives, they create heavier elements. This material gets mixed back into surrounding clouds of gas, which new stars and planets form out of. We wouldn’t be here on Earth if it weren’t for dead stars.”

It is important to note that the experience is not at all a tedious lecture. No physics foreknowledge is required; Obertas explains everything clearly, concisely, and without technobabble. In fact, portions of the presentation have little to do with astrophysics at all as they focus on constellations and what can be seen with the naked eye. Dazzling visuals that fill the room delight children and adults, alike. “I hope that people who are curious about science, space, and astronomy attend the shows and leave with a new perspective and appreciation for our place in the universe,” said Obertas. “You don’t need to be an expert to appreciate the cosmos we all share the night sky.”

Altogether, Obertas deftly weaves astronomy with entertainment to create an experience accessible for all educational backgrounds and recommendable for all ages. Obertas’ stunning visuals and eloquent descriptions are an excellent primer for anyone seeking a comfortable introduction to the cosmos. In both the literal and the metaphorical sense, the show is absolutely stellar.

The show is roughly an hour long and costs $10 per person. More information can be found here.

Dunlap Institute receives $23 million in funding

$10 million will go toward new Canadian radio astronomy data centre

Dunlap Institute receives $23 million in funding

A total of $23 million in new funding has been awarded to members of the Dunlap Institute for Astronomy & Astrophysics at U of T. Of this, $10 million was awarded to Dunlap Director Bryan Gaensler to lead the development of a Canadian radio astronomy data centre, and $13 million was awarded to Dunlap Professor Suresh Sivanandam to implement a new infrared spectrograph for the Gemini Observatory known as the Gemini InfraRed Multi-Object Spectrograph.

The awards were announced on October 12 at the annual Canada Foundation for Innovation (CFI) Innovation Fund awards ceremony held this year at the University of Manitoba. Canadian Minister of Science Kirsty Duncan presented the awards.

The underlying goal of Gaensler’s project is to manage the enormous amounts of data generated by radio telescopes that are currently surveying the sky. In some cases, like the recently completed radio telescope, the Canadian Hydrogen Intensity Mapping Experiment (CHIME), this can be as much as one terabyte of data every second.

“The data rates are enormous,” Gaensler said in an interview with The Varsity. “The data sizes are just completely unmanageable, so big that you couldn’t even save all the raw data to disk if you wanted to — you’d have to process some of it as you go.”

These vast, previously unimaginable amounts of data are only one aspect of what Gaensler terms “21st century astronomy.” Radio astronomers are also grappling with much larger fields of view than ever before: while telescopes used to point at small, specific regions of space, they now work to map the entire sky in radio wavelength. With this comes the need for near-instantaneous response times, as the chances of observing interesting, short-lived phenomena are much greater when you move from a small window to the entire sky.

While there are countless projects that can be done with an all-sky radio astronomy survey, Gaensler spoke in particular about three big scientific questions that he hopes to answer with the observations.

“Where does magnetism in the universe come from? What are all the different types of explosions and flares that happen in the universe? And what are the processes through which gas is converted into stars? So galaxy evolution, magnetism, and time-domain astronomy.”

The mandate of the CFI Innovation Fund is to support research that allows Canada to be competitive on a global stage. With the recent completion of CHIME and as the beginning of Gaensler’s radio astronomy data centre, it is clear that Canada is poised to become one of the key players in the radio astronomy landscape.

“We’re very much at the forefront,” said Gaensler, “and there’s some particular areas like pulsars and magnetism where we really own these topics.”

“[There are] all these great discoveries that Canadian radio astronomers have made in the past. We’re building on that heritage.”

Canada’s largest radio telescope begins map of the universe

Canada’s largest radio telescope begins map of the universe

Canada’s largest radio telescope begins map of the universe

September 7, 2017 marked an important day for an all-Canadian collaboration of astronomers and astrophysicists from the University of Toronto, the University of British Columbia, McGill University, and the National Research Council of Canada. After many years of development, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) began collecting data in an effort to create the largest map of the universe to date.

Located at the Dominion Radio Astrophysical Observatory just outside of Penticton, British Columbia, CHIME is the largest radio telescope in Canada. The instrument is made up of four 200-by-100-metre half-cylinders and has the computing power to process seven quadrillion computer operations every second.

According to U of T’s Dunlap Institute for Astronomy and Astrophysics, one of the collaborators on the project, the result of CHIME will be a three-dimensional map of radio waves covering half the night sky and extending billions of light years deep.

In attendance at a ceremony marking CHIME’s official launch was Minister of Science Kirsty Duncan, who installed the final piece of the telescope before it began operations. Also present was Dr. Keith Vanderlinde, a professor at the Dunlap Institute and a member of the CHIME collaboration.

With the data collected from CHIME, astronomers hope to answer a number of questions about the nature and evolution of the universe. CHIME will allow astronomers to learn more about the universe’s expansion history by shedding light on a period of time when a mysterious force known as dark energy — one of the main drivers behind the expansion of the universe — first began to play a role in the universe’s evolution.

While astronomers do know that the expansion of the universe is speeding up, many questions remain about the rate at which this is occurring and the ultimate fate that will befall the universe.

In addition to CHIME’s main scientific goal of mapping the universe and studying the universe’s expansion, the telescope will study other enigmatic radio phenomena in the sky. Back-end instrumentation installed on the telescope will allow astronomers to monitor pulsars, which are rapidly rotating remnants of long-dead giant stars that emit energy at radio wavelengths. They could provide future observational evidence of gravitational waves.

CHIME will also aid in the detection of Fast Radio Bursts (FRBs), which are short-lived but extremely powerful pulses of radio waves whose origins remain a mystery. These additional scientific goals are in collaboration with the National Radio Astronomy Observatory and scientists at the Perimeter Institute in Waterloo, Ontario.

After nearly six years of construction and $16 million invested into the project, collaborating astronomers are excited about the prospects for future scientific breakthroughs that CHIME holds.

“[CHIME] lets us do things that were previously impossible,” said Vanderlinde in a joint press release issued by the telescope’s primary collaborators. “We can look in many directions at once, run several experiments in parallel, and leverage the power of this new instrument in unprecedented ways.”

Dunlap Institute hosts stargazing event to celebrate Canada’s 150

Space enthusiasts gather at UTSG's back campus to observe the universe beyond

Dunlap Institute hosts stargazing event to celebrate Canada’s 150

U of T’s Dunlap Institute for Astronomy & Astrophysics hosted a “Canada 150 Star Party” on July 29. Around 500 stargazers came to the Back Campus Fields at UTSG to enjoy a night of unobstructed views of Jupiter, Saturn, the Moon, and satellites.

The Royal Astronomical Society of Canada (RASC) and the Fédération des astronomes amateurs du Québec sponsored similar events across the country, where the public was given a chance to take a closer look at the planets and the Moon, as well as ask astronomers and astrophysicists questions and inquire about their research.

“There’s lots of people all across Canada who are doing this at the same time, and that makes it pretty special,” said Jennifer West, a postdoctoral researcher at Dunlap and one of the organizers of the event.

“Jupiter and Saturn are the most interesting-looking through a telescope,” West continued, noting that the night was even more unique because both Saturn and Jupiter were visible. It is more common for only one of the two to be visible at a time.

The International Space Station, which orbits Earth every 90 minutes, was also spotted. “It’s just not always in a good spot for us to see,” West said. “But tonight we had a good pass where we could see it go across the sky.” Attendees also saw an iridium flare, which occurs when a communications satellite reflects sunlight toward Earth, making it very bright and easy to spot.

Eclipse glasses were distributed, along with star finders and pamphlets of information about the Star Party and the eclipse to come on August 21; U of T will be holding an eclipse party from 10:00 am to 5:00 pm at the CNE near the Princess Margaret Fountain. Canadians will only witness a partial eclipse. In Toronto, 70 per cent of the sun will be blocked. 

“You probably won’t even notice it was happening because the sky still stays pretty bright,” West said. “But if you wear the proper sun protection then you can, and you’ll see that a bite is taken out of it.”

West explained that solar eclipses are fairly common, occurring about every 18 months, though they are often not widely visible. The path of totality — an approximately 100-kilometre track of the Moon’s umbral shadow across Earth — will go through parts of fourteen states in the US.

“The last total eclipse in North America was 1979, and the next one [will be] in 2024, but [then] there won’t be one until 2099,” West stated. “So if you want to see an eclipse happen twice in the same city, you have to wait about 400 years.” She encourages others to travel to the US to witness the phenomenon, though if interested parties aren’t up to crossing the border, there are several events taking place in Canadian cities.

The Department of Astronomy and Astrophysics holds monthly astronomy tours at McLennan Physical Laboratories. The RASC also organizes similar events throughout the year, and for its 150th anniversary in 2018, West said it plans to host another national star party.

Ripples in spacetime found to be physical

Smashing ‘gravitational waves’ detection turns 100-year-old theory into fact

Exactly 100 years ago this month, Albert Einstein first proposed his theory of general relativity. Just over a week ago physicists announced that the theory has finally been confirmed.

Einstein’s ground-breaking theory predicted, amongst other things, that the acceleration of massive objects would cause ripples, called gravitational waves, which move through the fundamental backdrop of the universe, much in the same way that regular water waves may ripple in a cup of coffee. Whereas the ripples in your drink may be caused by the act of dropping a cube of sugar into your mug, these gravitational waves were successfully detected from the merging of two black holes over a billion light-years away.

Physicist David Reitze began the announcement bluntly, “Ladies and gentlemen, we have detected gravitational waves.” His words were met with jubilance at the Washington D.C. press conference, as he paused to let the significance of a century’s worth of painstaking effort to resonate among the audience.

At the University of Toronto’s Canadian Institute for Theoretical Astrophysics’ (CITA) webcast viewing event, which took place at the Burton Tower of the McLennan Physical Laboratories, the applause was only outdone by the radiant smiles that were shared among members of our own physics department.

“It’s momentous,” said Luis Lehner of the Perimeter Institute for Theoretical Physics in Waterloo. “It marks the beginning of our ability to peek at the universe through a completely new window.”

Gravitational waves are created by powerful events, like a binary black hole merging. Black holes are some of the densest and heaviest objects in the universe, with some having masses four million times greater than our sun. When these massive objects collide, they release a large burst of energy in a short amount of time. This energy is dispersed via ripples that travel throughout the entire universe. As gravitational waves travel, they compress space in one direction while stretching it in the other, a phenomena that scientists believed they could identify.

Over large distances however, gravitational waves usually fade as their energy dissipates, turning into no more than a whisper, leading scientists to fear that they would never be able to detect their existence. In this case, however, the energy released by the black hole collision was so great that its gravitational waves were able to remain detectable after travelling over a billion light-years to Earth.

Determined to detect gravitational waves, the U.S. National Science Foundation (NSF) invested more than $1.1 billion (US) into the construction of the Laser Interferometer Gravitational-wave Observatory (LIGO), which is described as “the most precise measuring device ever built.”

LIGO is comprised of two separate detectors, one in Livingston, Louisiana and one in Hanford, Washington. The detectors were designed around the concept of gravitational waves compressing space in one direction and expanding it in the other.

LIGO’s first observational run began in 2002 and ended in 2010 without having detected any gravitational waves. The NSF remained confident however, and a major upgrade was made to the detectors, making LIGO more sensitive. As it turns out this was a brilliant decision because the signal was only just quiet enough to have evaded detection before LIGO’s recent upgrade.

Each detector is made of two four-kilometre long perpendicular arms that have ultrapure glass mirrors at their ends. A beam of light is split into two and shot down both tubes, bouncing off the mirrors and returning to the starting point. LIGO is able to detect gravitational waves by measuring miniscule differences between the journeys of the two beams — if nothing interferes with the beams, their recombining will cancel each other out.

A light sensor is waiting in case something changes. Because of the perpendicular arms, the single dimension compression and stretching caused by gravitational waves will compress only one arm and stretch the other. So if a gravitational wave warps the path of one of the lasers, the two beams will be marginally misaligned, and the laser will hit the photodetector, alerting scientists to the deformity.

1.3 billion years ago, in a galaxy far far away, a pair of black holes were circling each other, slowly spiraling inwards, until they merged into one massive black hole. The two black holes had the equivalent weight of 36 and 29 times that of our sun respectively — much larger than most black holes, which typically have a mass equal to about ten times our sun. At the time of the collision, scientists estimate that they orbited each other at an astounding rate of 75 orbits per second.

The resulting black hole, however, was not the 65 solar masses one would expect from addition, but rather 62. This collision resulted in the mass of about three suns being converted to energy and released in a fraction of a second, which gave rise to particularly turbulent gravitational waves.

That wave first reached the LIGO facility in Louisiana, followed by the one in Washington state just seven milliseconds later. This allowed physicists to locate the black-hole collision as having occurred somewhere in the southern sky. The tiny time delay in itself proved that gravitational waves move at the speed of light.

As well as confirming a century-old theory, the detection of gravity waves may also have a practical application that can help us uncover more secrets of the universe. Until now scientists have relied on light to observe the cosmos, but if we can find a way to design telescopes that use gravitational waves, we may be able to probe into parts of the universe where even light cannot reach and drastically increase our observational field.

Such ‘Einstein telescopes’ could potentially track black-hole mergers, identify the collisions of ultra-dense neutron stars, investigate exploding stars and unearth theoretical “cosmic strings” left over from the big bang. Gravitational waves will give scientists an identifiable marker for when objects don’t emit visible light.

Scientists from the California Institute of Technology and the Massachusetts Institute of Technology have led the project, supported by a variety of international scientists and institutions. In fact, the scientific paper published names 1,004 individual authors.

The members of the LIGO Scientific Collaboration based at the University of Toronto include Harald Pfeiffer, Prayush Kumar, Kipp Cannon and Heather Fong, a physics graduate student. CITA researchers contributed to the search pipelines that identified the black hole merging and the theoretical waveforms that established the black hole masses and spins.

With this new discovery, we are one step closer to peering further into the final frontier and understanding where our universe came from.