What we know of the birth of a black hole has traditionally aligned with our perception of black holes themselves: dark, mysterious, and eerily quiet, despite their mass and influence. Stellar-mass black holes are born from the final gravitational collapse of massive stars several tens of the mass of our Sun which, unlike less massive stars, do not produce bright, supernova explosions.
Or at least, this is what astronomers had previously thought, because no one had observed in real time the collapse of a massive star leading to a supernova and forming a black hole. That is, until a team of researchers at Kyoto University reported their observations of SN 2022esa.
The Kyoto team had wondered whether all massive stars — those that are at least 30 times the mass of the Sun — die quietly without a supernova explosion, or if in some cases they are accompanied by an energetic and bright, special type of supernova explosion. The astronomers then discovered a type Ic-CSM class supernova that appeared to be an explosion of a Wolf-Rayet star, which are so incomprehensibly massive and luminous that astronomers believe them to be the progenitors of black hole formation.
To investigate the nature of this peculiar supernova, the research team utilized both the Seimei telescope in Okayama and the Subaru telescope in Hawaii. The team was able to observe and classify SN 2022esa as an Ic-CSM type supernova, demonstrating that the birth of a black hole is not necessarily quiet since this one could be observed with electro-magnetic signals.
They also discovered something else: the supernova shows a clear and stable period of about a month in its light-curve evolution, leading the team to conclude that it had been created by stable periodic eruptions of the star system once each year before the explosion. Such stable periodicity is only possible in a binary system, so the progenitor must have been a Wolf-Rayet star forming a binary with another massive star, or even a black hole. The fate of such a system, they determined, must be a twin of black holes.
“The fates of massive stars, the birth of a black hole, or even a black hole binary, are very important questions in astronomy,” says first author Keiichi Maeda. “Our study provides a new direction to understand the whole evolutional history of massive stars toward the formation of black hole binaries.”
This study also demonstrates the benefits of using two different telescopes that possess different observational properties. In this case, Seimei’s flexibility and promptness combined with Subaru’s high sensitivity proved to be an effective combination. The team plans to continue conducting research utilizing both telescopes in the coming years.
“We expect many interesting discoveries on the nature of astronomical transients and explosions like supernova,” says Maeda.
Naturally Occurring ‘Space Weather Station’ Elucidates New Way To Study Habitability Of Planets Orbiting M Dwarf Stars
Artist's rendition of the space weather around M dwarf TIC 141146667. The torus of ionized gas is sculpted by the star's magnetic field and rotation, with two pinched, dense clumps present on opposing sides of the star. CREDIT: llustration by Navid Marvi, courtesy Carnegie Science.
January 11, 2026
By Eurasia Review
How does a star affect the makeup of its planets? And what does this mean for the habitability of distant worlds? Carnegie’s Luke Bouma is exploring a new way to probe this critical question—using naturally occurring space weather stations that orbit at least 10 percent of M dwarf stars during their early lives. He is presenting his work at the American Astronomical Society meeting this week.
We know that most M dwarf stars—which are smaller, cooler, and dimmer than our own Sun—host at least one Earth-sized rocky planet. Most of them are inhospitable—too hot for liquid water or atmospheres, or hit with frequent stellar flares and intense radiation. But they could still prove to be interesting laboratories for understanding the many ways that stars shape the surroundings in which their planets exist.
“Stars influence their planets. That’s obvious. They do so both through light, which we’re great at observing, and through particles—or space weather—like solar winds and magnetic storms, which are more challenging to study at great distances,” Bouma explained. “And that’s very frustrating, because we know in our own Solar System that particles can sometimes be more important for what happens to planets.”
But astronomers can’t set up a space weather station around a distant star.
Or can they?
Working with Moira Jardine of the University of St. Andrews, Bouma homed in on a strange type of M dwarf called a complex periodic variable. They are young, rapidly rotating stars that observations show experience recurring dips in brightness. Astronomers weren’t sure if these dips in brightness were caused by starspots or by material orbiting the star.
“For a long time, no one knew quite what to make of these oddball little blips of dimming,” Bouma said. “But we were able to demonstrate that they can tell us something about the environment right above the star’s surface.”
Bouma and Jardine answered that question by creating “spectroscopic movies” of one of these complex periodic variable stars. They were able to demonstrate that they are large clumps of cool plasma that are trapped in the star’s magnetosphere—basically being dragged around with the star by its magnetic field—forming a kind of doughnut shape called a torus.
“Once we understood this, the blips in dimming stopped being weird little mysteries and became a space weather station,” Bouma exclaimed. “The plasma torus gives us a way to know what’s happening to the material near these stars, including where it’s concentrated, how it’s moving, and how strongly it is influenced by the star’s magnetic field.”
Bouma and Jardine estimate that at least 10 percent of M dwarfs could have plasma features like this early in their lives. So, these space weather stations could help astronomers learn a great deal about particles from stars contribute to planetary conditions.
Next, Bouma hopes to reveal where the material in the torus comes from—the star itself or an external source.
“This is a great example of a serendipitous discovery, something we didn’t expect to find but that will give us a new window into understanding planet-star relationships,” Bouma concluded. “We don’t know yet if any planets orbiting M dwarfs are hospitable to life, but I feel confident that space weather is going to be an important part of answering that question.”
