Anthony Moffat, is a distinguished Professor Emeritus at the Université de Montréal, whose research focus is the fascinating realm of massive stars. These are giant stars with initial masses exceeding 8 times that of our Sun. They follow a dramatic lifecycle, culminating in a powerful explosion known as a supernova, which can leave behind dense remnants like neutron stars or enigmatic black holes.
What sets massive stars apart is their astonishing brightness. To put it into perspective, a single star with a mass of 100 times that of our Sun can emit the equivalent of a million suns’ worth of light. Additionally, these stars are characterized by their formidable stellar winds, which can be billions of times stronger than the solar wind we experience. These powerful winds play a crucial role in various cosmic phenomena, including the formation of comets and the mesmerizing auroras.
Despite their rarity and relatively short lifespans, massive stars contribute immensely to the universe. They radiate copious amounts of energy, primarily in the form of lethal ultraviolet radiation, and expel matter enriched with heavy elements into the surrounding space. This enriched material becomes the building blocks for the formation of new generations of stars and planets, including Earth-like worlds. This process was particularly significant in the early Universe when the very first stars were born, and many of them were exceptionally massive. Anthony Moffat’s work unravels the story of these stellar behemoths, shedding light on their vital role in shaping the cosmos and laying the foundation for the celestial wonders we see today.
He investigates whether the force of radiation pressure alone can propel the intense winds of stars just before they explode as supernovae, particularly during the He-burning phase when they become Wolf-Rayet stars. To accomplish this, he utilized the Canadian space telescope aboard the MOST microsatellite.
Moffat also helped in creating the BRITE-Constellation microsatellite system, designed to scrutinize the subtle instability properties of numerous bright stars on a small scale. Additionally, he explores the mechanisms by which winds accelerate around hot, luminous stars and the role of magnetic fields in this process.
Another puzzle he seeks to unravel relates to the formation and survival of dust grains in the harsh environments of hot, luminous stars. He probes the upper limit of mass for the most colossal stars in our Universe, a question that remains open-ended—could it be 100, 150, or even 200 times the mass of our Sun?
Prof. Moffat’s research also extends to understanding the abundance of Wolf-Rayet (WR) stars scattered throughout our Galaxy, many of which remain concealed by interstellar dust. In particular, he investigates whether WR stars indeed undergo explosive transformations into supernovae, giving rise to some of the most energetic but short-lived occurrences in the Universe — gamma-ray bursts.