Michael Pereira

U of T astronomers and Kâpapâmahchakwêw – Wandering Spirit School collaborate on science programming for Indigenous students

rahul.kalvapalle — Tue, 14 May 2024 18:23:37 +0000

U of T astronomers and Kâpapâmahchakwêw – Wandering Spirit School collaborate on science programming for Indigenous students

rahul.kalvapalle Tue, 05/14/2024 - 14:23

Cutline

Students, teachers and caregivers from Kâpapâmahchakwêw – Wandering Spirit School gather with U of T astronomers to watch the April 8 total solar eclipse at Chiefswood Park on Six Nations of the Grand River (photo by Suresh Sivanandam)

Michael Pereira

Topic

Our Community

Indigenous Initiatives

Astronomy & Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Indigenous

Truth and Reconciliation

Subheadline

The groundwork is currently being laid for a coding club and mentoring programs, among other initiatives

A group of astronomers from the University of Toronto and students, teachers and caregivers from Toronto’s Kâpapâmahchakwêw – Wandering Spirit School recently shared a once-in-a-lifetime experience: witnessing a total solar eclipse.

The April 8 gathering, which took place in Chiefswood Park on Six Nations of the Grand River, saw the astronomers bring telescopes with solar filters that allowed viewers to observe sunspots and watch as the moon slowly eclipsed the sun. The event also served as a forum for young learners and community members to share traditional knowledge and ask plenty of questions.

It was one of many engagements planned as part of a partnership between U of T’s Dunlap Institute for Astronomy & Astrophysics and the Kâpapâmahchakwêw – Wandering Spirit School, which was founded in 1977 and gives students from kindergarten to Grade 12 the opportunity to learn about Anishinaabe cultural traditions.

Totality at Chiefswood Park (photo by Kara Manovich)

In the future, there are also plans for a coding club, mentoring and tutoring programs, and training for teachers.

“Kâpapâmahchakwêw – Wandering Spirit School is grateful for the growing partnership with Dunlap because it provides an opportunity to practise reciprocity in knowledge sharing,” said Elise Twyford, the school’s principal. “The students and community learned about – and experienced – astrophysics and astronomy, and also had the opportunity to build their skills in sharing traditional knowledge and world views.

“I appreciate the care and thoughtfulness of the Dunlap and University of Toronto team in collaborating with Kâpapâmahchakwêw students as partners in learning.”

The roots of the partnership stretch back to 2022 when Emma Stromberg, Indigenous partnership adviser at the Faculty of Arts & Science, and Associate Professor Susan Hill, director of the Centre for Indigenous Studies, approached Dunlap with an opportunity to work with teachers and students from Kâpapâmahchakwêw.

A close-up photo of the moon totally eclipsing the sun on April 8 above Chiefswood Park (photo by Suresh Sivanandam)

“We wanted to see if we could match up the needs and interests of the school to resources at U of T, to build something that can be sustained,” Stromberg says. “Consistent with U of T’s commitments to reconciliation, it is incumbent on all of us to think of ways to redress, in small and big ways, the impacts of settler colonialism and push resources into the community wherever possible.”

Some 20 members of the Dunlap community have since volunteered to help, with many of them recently participating in a workshop with John Croutch from the Office of Indigenous Initiatives to learn about the continued impacts of settler colonialism and what it means to be an ally to Indigenous Peoples.

The U of T astronomers said the opportunity to share a total solar eclipse was a memorable moment for everyone involved.

“You could hear lots of kids screaming in excitement and people gasping in awe at seeing totality,” said Associate Professor Suresh Sivanandam, interim director of the Dunlap Institute for Astronomy & Astrophysics in the Faculty of Arts & Science. “When I walked out of there, I thought, ‘These are the moments in my job where I feel completely fulfilled because I helped other people experience the joy of astronomy.’”

Students recreate the total solar eclipse with paint and pastels on black paper (photo by Emma Stromberg)

Professor Roberto Abraham, chair of the faculty’s David A. Dunlap department of astronomy and astrophysics, said he was the same age as some of the students when he first saw a total solar eclipse.

“It was magic,” he said. “Once you see a total solar eclipse, you won’t be the same person afterwards.”

Earlier this year, Sivanandam and Abraham visited the school to meet students, teachers and staff and hear about how astronomers at U of T can best support them.

For Twyford, the relationship with U of T immerses Kâpapâmahchakwêw students in the fields of astronomy and astrophysics in ways that wouldn’t be possible in the classroom.

“I know that many students now see the wonder and possibility of these sciences and are even more motivated to continue their learning,” Twyford said. “It also helps to complement the traditional and cultural.”

'A black box in astronomy knowledge': PhD researcher probes the earliest stars in the universe

Christopher.Sorensen — Tue, 26 Mar 2024 18:20:25 +0000

'A black box in astronomy knowledge': PhD researcher probes the earliest stars in the universe

Christopher.Sorensen Tue, 03/26/2024 - 14:20

Cutline

PhD researcher Margaret Ikape presents at the Astronomy on Tap T.O. event (photo by Alicia Richardson)

Michael Pereira

Topic

Our Community

Astronomy & Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Graduate Students

Space

Subheadline

Margaret Ikape is working to determine the properties of the first stars and how they influenced everything that followed

As a child, Margaret Ikape had a prime view of the stars from her hometown of Lagos, Nigeria.

“When I was really young, I saw a shooting star. And that got me looking up at the night sky a lot more,” Ikape says. She recalls thinking: “Can I count all the stars? Can I really go to a star? What would it be like if I could really go to a star? How long would it take?”

Today, Ikape is still looking at stars with the same curiosity, albeit ones that are much farther away. A PhD researcher at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics and David A. Dunlap Department of Astronomy & Astrophysics, she’s working to tell the story of the first stars in the universe, and how they influenced everything that followed.

Theory predicts that ultraviolet light from the first stars was so powerful that it ionized — or split — some of the first hydrogen atoms back into protons and electrons. This period of cosmic history is known as the Epoch of Reionization (EoR). During this time, the first stars and galaxies began to form, and with them, the universe as we know it today.

Ikape is working to determine the properties of these first stars, like how big they were and how long the reionization took. “That period is like a black box in astronomy knowledge. We know it happened, because the universe is ionized today, but we don’t know many details about it,” Ikape says.

A representation of the evolution of the universe over 13.77 billion years (image by NASA / WMAP Science Team)

Current optical telescopes cannot see back far enough to capture the EoR, so Ikape uses thousands of computer simulations to reimagine it and test theories in a kind of virtual sandbox shaped by what we know of the universe. Some of these simulations require significant processing power and must be run through the “Helen” computing cluster, named after renowned Canadian astronomer Helen Sawyer Hogg.

Ikape also learns about the EoR by studying the first light emitted in the universe, the Cosmic Microwave Background (CMB). As light from the CMB travels to Earth, it passes through all that is between us and the point in cosmic history at which the CMB was emitted, approximately 380,000 years after the Big Bang. Ikape can isolate how light from the CMB was impacted by the EoR and analyze it to tell us more about this time.

“Margaret’s work connects models and simulations of how the first stars in the universe lit up and ionized the surrounding gas with our observations of the cosmic microwave light—so she is the detective piecing the story together,” says Associate Professor Renée Hložek, Ikape’s PhD supervisor.

Ikape has forecasted that a new generation of telescopes will unlock more details about this mysterious period and the universe’s first stars, including the Simons Observatory and the fourth-generation ground-based cosmic microwave background experiment, or CMB-S4. She co-authored research that predicts that the CMB-S4 will help scientists close in on when the EoR began and how long it lasted.

A nine-year Wilkinson Microwave Anisotropy Probe (WMAP) heat map of temperature fluctuations in the CMB (photo by NASA/WMAP)

When she isn’t unpacking the mysteries of distant stars, Ikape is involved in outreach initiatives on the ground.

She’s an instructor with the Pan-African School for Emerging Astronomers, a bi-annual school for emerging astronomers in Africa that aims to introduce astronomy undergraduate students to research practices and career avenues in the field, and participated in its inaugural program in Zambia in 2022.

In Toronto, Ikape was recently a speaker at Astronomy on Tap and has given presentations on astronomy at libraries, high schools and even a long-term care home.

“We are lucky to have students like Margaret at the Dunlap Institute; she combines her scientific curiosity with a passion for sharing what she learns with the broader community and training the next generation of bright minds,” Hložek says.

“The universe fascinates me a lot and I’m super excited every time I think about it," Ikape says. "So I think that everybody should know about it.”

U of T astronomers discover first population of binary stripped stars

rahul.kalvapalle — Wed, 20 Dec 2023 15:22:31 +0000

U of T astronomers discover first population of binary stripped stars

rahul.kalvapalle Wed, 12/20/2023 - 10:22

Cutline

Artist's impression of a massive star stripping the hydrogen envelope of its companion star in a binary system (illustration by Navid Marvi, courtesy of the Carnegie Institution for Science)

Michael Pereira

Topic

Breaking Research

Astronomy & Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Research and Innovation

Space

Subheadline

New findings confirm the existence of hot helium stars long thought to be at the heart of hydrogen-poor supernovae and neutron star mergers

Astronomers at the University of Toronto have discovered a population of massive stars that have been stripped of their outer hydrogen layer by companion stars.

For over a decade, scientists have theorized that approximately one in three massive stars are stripped of their hydrogen envelope in binary systems (systems where two stars are gravitationally bound to one another). Yet, until now, only one possible candidate had been identified.

The findings, published in Science, shed light on the hot helium stars that are believed to be the origins of hydrogen-poor core-collapse supernovae and neutron star mergers.

“If it turned out that these stars are rare, then our whole theoretical framework for all these different phenomena is wrong, with implications for supernovae, gravitational waves and the light from distant galaxies,” said Maria Drout, assistant professor in the David A. Dunlap department of Astronomy & Astrophysics at the University of Toronto and an associate at the Dunlap Institute for Astronomy & Astrophysics.

“This finding shows these stars really do exist.”

It also opens up possibilities for more detailed research going forward. “For example, predictions for how many neutron star mergers we should see are dependent on the properties of these stars, such as how much material comes off of them in stellar winds," Drout says. "Now, for the first time, we’ll be able to measure that, whereas people have been extrapolating it before."

Assistant Professor Maria Drout with the Magellan Telescope at Las Campanas Observatory (photo by Tom Holoien/Maria Drout)

Drout and her colleagues propose that these newly discovered stars will eventually explode as hydrogen-poor supernovae. These star systems are also thought to be necessary to form neutron star mergers.

In fact, the researchers believe that a few objects in their current sample are stripped stars with neutron star or blackhole companions. These objects are at the stage immediately before they become double-neutron-star or neutron-star-plus-blackhole systems that could eventually merge.

“Many stars are part of a cosmic dance with a partner, orbiting each other in a binary system. They’re not solitary giants but part of dynamic duos, interacting and influencing each other throughout their lifetimes,” says Bethany Ludwig, a PhD student in the David A. Dunlap department of Astronomy & Astrophysics and third author on the paper. “Our work sheds light on these fascinating relationships, revealing a universe that is far more interconnected and active than we previously imagined.

“Just as humans are social beings, stars too, especially the massive ones, are rarely alone.”

(Left to right): Bethany Ludwig, Anna O’Grady, Maria Drout and Ylva Götberg (all authors on the paper) at the Magellan Telescopes at Las Campanas Observatory in Chile (photo by Ylva Götberg)

As stars evolve and expand to become red giants, the hydrogen at the outer edges of one can be stripped by the gravitational pull of its companion star – leaving a very hot helium core exposed. The process can take tens of thousands or even hundreds of thousands of years.

Stripped stars are difficult to find because much of the light they emit is outside of the visible light spectrum and can be obstructed by dust in the universe or outshone by their companion stars.

Drout and her collaborators began their search in 2016. Having studied hydrogen-poor supernovae during her PhD, Drout set out to find the stripped stars thought to be at the heart of these supernovae during a NASA Hubble postdoctoral fellowship at the Observatories of the Carnegie Institution for Science.

The researchers, who include co-author Ylva Götberg, assistant professor at the Institute of Science and Technology Austria, later designed a survey to look in the ultraviolet part of the spectrum where extremely hot stars emit most of their light. Using data from the Swift Ultra-Violet/Optical Telescope, they collected brightness data for millions of stars in the Large and Small Magellanic Clouds, two of the closest galaxies to Earth.

Ludwig, who developed the first wide-field UV catalogue of the Magellanic Clouds, used UV photometry to detect systems with unusual UV emissions – signaling the possible presence of a stripped star.

The researchers used this ultraviolet dataset of the Large and Small Magellanic Clouds, the two closest major galaxies to our own, to identify the candidate systems (image by NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)

The team carried out a pilot study of 25 objects, obtaining optical spectroscopy with the Magellan Telescopes at Las Campanas Observatory between 2018 and 2022, and demonstrated that the stars were hot, small, hydrogen-poor, and in binary systems – all consistent with their model predictions.

Currently, the researchers are continuing to study the stars identified in the paper and expanding their search to find more. They will be looking both within our own Milky Way and nearby galaxies with approved programs on the Hubble Space Telescope, the Chandra X-ray Telescope, the Magellan Telescopes and the Anglo-Australian Telescope.

As part of this publication, all theoretical models and data used to identify these stars have been made public and available to other scientists.

Collaborating institutions include the University of Toronto, the Observatories of the Carnegie Institution for Science, Max-Planck-Institut für Astrophysik, Anton Pannekoek Institute for Astronomy, Dunlap Institute for Astronomy & Astrophysics and Steward Observatory.