Astronomers have long been familiar with the image of white dwarfs, likened to "cosmic vampires", sucking matter from nearby companion stars.
This process, which usually ends in a supernova explosion that destroys both bodies, has been well studied.
However, a recent discovery from the California Institute of Technology (USA) is revealing a surprising secret: the existence of a third star, playing the role of a silent "matchmaker" in these systems.
Illustration showing a white dwarf sucking material from a victim star (Image: Caltech).
The study, based on data from the European Space Agency's Gaia mission, identified 50 triple-star systems containing variable stars. In these systems, two close stars form a primary pair, while a third star orbits at a much greater distance.
Results from 2,000 computer simulations showed that in about 20% of cases, it was the gravitational pull from the third star that altered the orbits of the binary stars, bringing them closer together without going through the common gas envelope stage as traditionally assumed.
The pivotal role of the "third party"
Previously, astronomers believed that most variable stars formed through common envelope evolution.
Accordingly, a star swells into a red giant and engulfs its companion star.
When the two stars interact, this shell is ejected, leaving a white dwarf orbiting a companion star close enough to begin the process of capturing material.
Illustration showing ESA's Gaia mission observing the Milky Way (Image: ESA).
However, the new findings suggest that this model is not the only way forward. In the team's simulations, in up to 60 percent of cases, the common gas envelope still forms, but is triggered by the impact of a third star.
Only about 20% of the remaining cases are gas shells formed in the traditional way, without the presence of a third star.
Notably, the team predicts that up to 40% of catastrophic events in the real world could be caused by triple-star systems, a figure much higher than what Gaia's observational data has ever recorded.
The reason may be that many third stars are too far away or have too weak a light to be detected, or have even been ejected from the system due to strong gravitational effects.
The data also show that triple star systems with the third star's orbit greater than 100 astronomical units (100 times the distance from Earth to the Sun) are more likely to form variables.
"For the past 50 years, astronomers have used the general gas envelope model to explain variable star formation. But now we find that many of these systems are actually the products of triple star interactions," said researcher Kareem El-Badry.
This discovery opens a new direction of research, challenging long-standing assumptions about the evolution of star systems in the universe.
Source: https://dantri.com.vn/khoa-hoc/phat-hien-ke-giau-mat-dang-am-tham-giet-chet-ca-he-sao-20250715130457970.htm
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