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In humans, twins or higher multiples are relatively rare, with single births being the norm. For massive stars, however, the opposite seems to be true: most are born and live as pairs. This was already known for massive stars in our own metal-rich Milky Way, but new observations reveal that massive stars in metal-poor galaxies also frequently have close companions.

In recent years, astronomers have realized that interactions between stellar companions play a crucial role in the evolution of massive stars in the Milky Way. Until now, however, it was unclear whether massive stars in more distant, metal-poor galaxies were also part of binary systems.

“We used the Small Magellanic Cloud as a time machine,” explains Hugues Sana from KU Leuven (Belgium), the lead author of the study. “The Small Magellanic Cloud is a relatively nearby metal-poor galaxy, an environment representative of that of much more distant galaxies when the universe was only a few billion years old.”

Studying massive stars outside of the Milky Way is difficult because the stars are far away and we receive little light from them. The researchers used the FLAMES spectrograph on the Very Large Telescope of the European Southern Observatory in Chile. It is one of the largest telescopes on Earth. FLAMES has 132 fiber optics, each of which can be directed at a different star, which can then be observed simultaneously.

Over a period of 3 months, the researchers observed the acceleration and deceleration of 139 massive O-type stars at 9 different times. These stars have masses between 15 and 60 times that of our Sun. They are hot, shine brightly, and end their lives in supernova explosions. In the process, the star's core collapses into a black hole. The results show that over 70 percent of the observed stars accelerate and decelerate. That is a sign of a close companion.

“The fact that massive stars in the Small Magellanic Cloud have a partner suggests that the first stars in the universe, which we suspect were also massive, had partners, too," says co-author Julia Bodensteiner of the University of Amsterdam (the Netherlands). "Perhaps some of those systems end up as two black holes orbiting each other. It’s an exciting thought."

These black holes are of particular interest to Dr. Vincent Hénault-Brunet and his research group at Saint Mary’s, who study their subsequent evolution in dense clusters long after their progenitor massive stars have exploded as supernovae.

Dr. Luigi Gallo was honoured at Winter Convocation with the President’s Award for Excellence in Research for his contributions to astrophysics.

As an astrophysicist in high-profile international research projects, Dr. Luigi Gallo has been involved in major missions with the Japan Aerospace Exploration Agency (JAXA), NASA, and the Canadian Space Agency, and has received more than $10-million in funding for projects such as the Astro-H Metrology System.

After a stint in industry, Dr. Gallo returned to academia and completed his PhD at the prestigious Max Planck Institute for Extraterrestrial Physics in Germany, and then joined JAXA before becoming a faculty member at Saint Mary’s University in 2007.

A prolific publisher, Dr. Gallo is credited with more than 80 successful observing proposals and more than 150 refereed publications written as part of his research on black holes and instrumentation, work with peers, and as a supervisor to many of his students and postdocs. He has also published work with large collaborations, including papers by the Hitomi Collaboration, which he made significant contributions to, as well as other publications on future missions.

As a professor, Dr. Gallo is focused on supporting the next generation of researchers, co-writing papers with undergraduate and graduate students who have gone on to higher-level studies and research of their own. He contributes significant time and knowledge to the advancement of his field through committee work and outreach initiatives and as a member of the Canadian Astronomical Society.

The President's Award for Excellence in Research honours continued exceptional contributions to research and scholarship conducted by a full-time Saint Mary's University faculty member. More information can be found at smu.ca/fgsr/presidents-award.

Congratulations Dr. Luigi Gallo!

In humans, twins or higher multiples are relatively rare, with single births being the norm. For massive stars, however, the opposite seems to be true: most are born and live as pairs. This was already known for massive stars in our own metal-rich Milky Way, but new observations reveal that massive stars in metal-poor galaxies also frequently have close companions.

In recent years, astronomers have realized that interactions between stellar companions play a crucial role in the evolution of massive stars in the Milky Way. Until now, however, it was unclear whether massive stars in more distant, metal-poor galaxies were also part of binary systems.

“We used the Small Magellanic Cloud as a time machine,” explains Hugues Sana from KU Leuven (Belgium), the lead author of the study. “The Small Magellanic Cloud is a relatively nearby metal-poor galaxy, an environment representative of that of much more distant galaxies when the universe was only a few billion years old.”

Studying massive stars outside of the Milky Way is difficult because the stars are far away and we receive little light from them. The researchers used the FLAMES spectrograph on the Very Large Telescope of the European Southern Observatory in Chile. It is one of the largest telescopes on Earth. FLAMES has 132 fiber optics, each of which can be directed at a different star, which can then be observed simultaneously.

Over a period of 3 months, the researchers observed the acceleration and deceleration of 139 massive O-type stars at 9 different times. These stars have masses between 15 and 60 times that of our Sun. They are hot, shine brightly, and end their lives in supernova explosions. In the process, the star's core collapses into a black hole. The results show that over 70 percent of the observed stars accelerate and decelerate. That is a sign of a close companion.

“The fact that massive stars in the Small Magellanic Cloud have a partner suggests that the first stars in the universe, which we suspect were also massive, had partners, too," says co-author Julia Bodensteiner of the University of Amsterdam (the Netherlands). "Perhaps some of those systems end up as two black holes orbiting each other. It’s an exciting thought."

These black holes are of particular interest to Dr. Vincent Hénault-Brunet and his research group at Saint Mary’s, who study their subsequent evolution in dense clusters long after their progenitor massive stars have exploded as supernovae.

In humans, twins or higher multiples are relatively rare, with single births being the norm. For massive stars, however, the opposite seems to be true: most are born and live as pairs. This was already known for massive stars in our own metal-rich Milky Way, but new observations reveal that massive stars in metal-poor galaxies also frequently have close companions.

In recent years, astronomers have realized that interactions between stellar companions play a crucial role in the evolution of massive stars in the Milky Way. Until now, however, it was unclear whether massive stars in more distant, metal-poor galaxies were also part of binary systems.

“We used the Small Magellanic Cloud as a time machine,” explains Hugues Sana from KU Leuven (Belgium), the lead author of the study. “The Small Magellanic Cloud is a relatively nearby metal-poor galaxy, an environment representative of that of much more distant galaxies when the universe was only a few billion years old.”

Studying massive stars outside of the Milky Way is difficult because the stars are far away and we receive little light from them. The researchers used the FLAMES spectrograph on the Very Large Telescope of the European Southern Observatory in Chile. It is one of the largest telescopes on Earth. FLAMES has 132 fiber optics, each of which can be directed at a different star, which can then be observed simultaneously.

Over a period of 3 months, the researchers observed the acceleration and deceleration of 139 massive O-type stars at 9 different times. These stars have masses between 15 and 60 times that of our Sun. They are hot, shine brightly, and end their lives in supernova explosions. In the process, the star's core collapses into a black hole. The results show that over 70 percent of the observed stars accelerate and decelerate. That is a sign of a close companion.

“The fact that massive stars in the Small Magellanic Cloud have a partner suggests that the first stars in the universe, which we suspect were also massive, had partners, too," says co-author Julia Bodensteiner of the University of Amsterdam (the Netherlands). "Perhaps some of those systems end up as two black holes orbiting each other. It’s an exciting thought."

These black holes are of particular interest to Dr. Vincent Hénault-Brunet and his research group at Saint Mary’s, who study their subsequent evolution in dense clusters long after their progenitor massive stars have exploded as supernovae.