Sabrina Berger

Meet Sabrina Berger from McGill University!

Fast radio bursts (FRB) are short, sub-second bursts that are some of the brightest objects in the radio sky when they go off. These bursts’ astrophysical origins are still unknown. Last year an FRB was localized to a magnetar, an extremely dense and magnetized stellar remnant, within the Milky Way. Localizing FRBs can narrow down their potential origins, a first step towards understanding what causes them. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) located in British Columbia, has discovered more than one thousand FRBs, orders of magnitude more than previous instruments. CHIME Outriggers is an upcoming experiment to use the original CHIME instrument along with other dishes spaced up to thousands of kilometers apart to create better localization capabilities. Sabrina’s research focuses on using Global Positioning Satellites (GPS) to help remove errors in localization of FRBs caused by the telescopes being located at different places on Earth. Hopefully, we’ll be able to localize many more FRBs to within their home galaxies in the next few years with CHIME Outriggers!



A dispersed (bottom panel) and dedispersed (top panel) spectra of the most prolific fast radio burst signal. This FRB repeats which has allowed us to observe it with various telescope arrays. Credit: Breakthrough Listen



We are pleased to announce that your CASCA Graduate Student Committee is launching a new seminar series entitled CaTS — Canadian Telescope Seminars. The goal of these quarterly seminars is to highlight the opportunities provided to Canadian graduate students by the many and diverse astronomical observatories located in Canada or heavily involved in Canadian astronomy. During each session, an observatory will present its telescopes, instruments, and personnel. 

Since the goal is to bolster graduate student involvement at these institutions, the observatories will focus on how graduate students can implicate themselves in the observatory through research projects and/or observation time proposals. Unless otherwise noted, the sessions take place at 3 PM EST.


Zoom info:


Date (M/D/Y) Observatory Youtube Link PDF Link
03/10/2021 Canada-France-Hawai’i Telescope (CFHT) CFHT.pdf
04/28/2021 James Clark Maxwell Telescope (JCMT)–iiCQ JCMT.pdf
05/19/2021 Square Kilometer Array (SKA) SKA.pdf
06/16/2021 Canadian Space Telescope (CASTOR) N/A ————
07/14/2021 Gemini Observatory N/A due to technical difficulties Gemini.pdf
10/27/2021 James Web Space Telescope (JWST) JWST.pdf
11/17/2021 Canadian Hydrogen Intensity Mapping Experiment (CHIME) CHIME-FRB.pdf & CHIME-Pulars.pdf

Spectacular ‘Honeycomb Heart’ Revealed in Iconic Stellar Explosion

A unique ‘heart shape’, with wisps of gas filaments showing an intricate honeycomb-like arrangement, has been discovered at the centre of the iconic supernova remnant, the Crab Nebula. Using SITELLE at the Canada-France-Hawaii Telescope (CFHT), astronomers mapped the void in unprecedented detail, creating a realistic three-dimensional reconstruction. The new work is published in Monthly Notices of the Royal Astronomical Society

The Crab Nebula, also known as Messier 1, exploded as a dramatic supernova in 1054 CE, and was observed over the subsequent months and years by ancient astronomers across the world. The resulting nebula – the remnant of this enormous explosion – has been studied by amateur and professional astronomers for centuries. However, despite this rich history of investigation, many questions remain about what type of star was originally there and how the original explosion took place.

Thomas Martin, the researcher at Université Laval who led the study, hopes to answer these questions using a new 3D reconstruction of the nebula. “Astronomers will now be able to move around and inside the Crab Nebula and study its filaments one by one,” said Martin.

The team used powerful SITELLE spectrograph at CFHT on Maunakea to compare the 3D shape of the Crab to two other supernova remnants. Remarkably, they found that all three remnants had ejecta arranged in large-scale rings, suggesting a history of turbulent mixing and radioactive plumes expanding from a collapsed iron core.

Astronomers use computer simulations of supernova explosions to estimate what patterns the ejected materials make as they expand into a supernova remnant. Each possible explosion is associated with a specific pattern- or fingerprint. The honeycomb pattern observed by the team resembles the fingerprint caused by the collapse of a heavier iron core. Co-author Dan Milisavljevic, an assistant professor at Purdue University and supernova expert, concludes that the fascinating morphology of the Crab seems to go against the most popular explanation of the original explosion.

“The Crab is often understood as being the result of an electron-capture supernova triggered by the collapse of an oxygen-neon-magnesium core, but the observed honeycomb structure may not be consistent with this scenario,” Milisavljevic said. “Future work mapping the Crab’s chemical distribution of elements is needed to address this inconsistency.”

The new reconstruction was made possible by the ground-breaking technology used by SITELLE, which incorporates a Michelson interferometer design allowing scientists to obtain over 300,000 high-resolution spectra of every single point of the nebula.

“SITELLE was designed with objects like the Crab Nebula in mind; its wide field of view and adaptability make it ideal to study nearby galaxies and even clusters of galaxies at large distances,” said co-author Laurent Drissen, co-author on the paper and professor at Université Laval.

Supernova explosions are among the most energetic and influential phenomena in the universe. Consequently, Milisavljevic adds: “it is vital that we understand the fundamental processes in supernovae which make life possible. SITELLE will play a new and exciting role in this understanding.”

Full release for links to video and paper: