Astronomers unearthed a black hole surpassing our sun's mass by 33 times, ranking as the largest known in the Milky Way, apart from the supermassive one lingering at the galactic core.
This recently spotted black hole resides approximately 2,000 light-years away from Earth, a relatively near distance in cosmic standards, situated in the Aquila constellation. It boasts a companion star orbiting around it, as confirmed by researchers on Tuesday. A light year, spanning 5.9 trillion miles (9.5 trillion km), signifies the distance light traverses in a year.
These enigmatic entities, black holes, exhibit extraordinary density and gravitational pull so intense that even light cannot evade their grasp, rendering their detection challenging. However, this particular black hole was pinpointed through observations within the European Space Agency's Gaia mission, which is compiling an extensive stellar census. Its presence induced a noticeable wobble in its accompanying star. Ground-based observatories, including the European Southern Observatory's Very Large Telescope in Chile, contributed data crucial for verifying the black hole's mass.
Pasquale Panuzzo, a research engineer at the French National Center for Scientific Research (CNRS) stationed at the Paris Observatory and the study's lead author, expressed astonishment, stating, "This black hole is not only exceedingly massive but also remarkably peculiar in various aspects. It truly presents phenomena we never anticipated witnessing." One intriguing detail is the black hole, dubbed Gaia BH3, and its companion's counterintuitive galactic trajectory, moving in the opposite direction of typical stellar orbits within the Milky Way.
The researchers indicated that Gaia BH3 likely emerged following the demise of a star more than 40 times the mass of our sun.
Black holes originating from the collapse of a solitary star are termed stellar black holes. Tsevi Mazeh, an astronomer and co-author of the study from Tel Aviv University in Israel, affirmed Gaia BH3 as the largest-known stellar black hole.
In size, stellar black holes are overshadowed by the supermassive black holes residing at the cores of most galaxies. One such entity, Sagittarius A* (Sgr A*), occupies the Milky Way's center. It boasts a mass 4 million times that of our sun and lies approximately 26,000 light-years distant from Earth.
The progenitor star of Gaia BH3 consisted predominantly of hydrogen and helium. Stars in the early universe exhibited such a chemical composition, termed low metallicity. This particular star likely formed early in cosmic history, possibly 2 billion years after the Big Bang event.
Upon the conclusion of its lifespan, characterized by a supernova explosion, the star ejected some material into space while its remnants violently collapsed, yielding a black hole.
The identification of Gaia BH3, as per Panuzzo, lends support to stellar evolution models suggesting that massive stellar black holes can arise solely from a low metallicity progenitor star like this one.
The companion star of Gaia BH3, comparable in age to its predecessor, possesses approximately 76% of the sun's mass and is slightly cooler but emits about ten times more light. It orbits the black hole in an elliptical trajectory, ranging from about 4.5 to 29 astronomical units (AU), where one AU represents the average distance between Earth and the sun. By comparison, Jupiter orbits at about five AU from the sun, while Neptune orbits at around 30 AU.
Observatoire de Paris astronomer and study co-author Elisabetta Caffau expressed surprise at the companion star's ordinary chemical composition, suggesting it was unaffected by the black hole's supernova explosion.
The upper limit for the mass of stellar black holes remains a subject of active scientific discourse, according to Panuzzo.
