Astronomers have unveiled a remarkable celestial discovery: a black hole that appears to have formed without the usual explosive supernova that marks the death of massive stars. This finding challenges the conventional understanding of black hole formation and opens up new avenues for astronomical research.
The black hole in question, known as V404 Cygni, is located approximately 7,800 light-years from Earth in the constellation Cygnus. Unlike typical black holes that are born from the cataclysmic explosion of a dying star, this one seems to have emerged through a ‘gentle’ process known as direct collapse.
What makes V404 Cygni particularly intriguing is its gravitational relationship with not just one, but two ordinary stars, forming a rare triple system. Previously, V404 Cygni was thought to be orbiting a single companion star. However, recent data from the European Space Agency’s Gaia space observatory has revealed a second companion, bound by gravity yet orbiting at a much greater distance.
“In most cases, black holes form after a massive star explodes in a supernova, leaving behind a dense core,” explained Kevin Burdge, an astronomer at the Massachusetts Institute of Technology and lead author of the study published in the journal Nature. “But in this case, the absence of such an explosion suggests that the star collapsed directly into a black hole.”
The presence of the intact triple system is a crucial clue. Had the original star exploded, the force of the supernova would likely have disrupted the gravitational balance, causing the system to break apart. The survival of this delicate arrangement implies a different formation pathway.
The black hole, estimated to be nine times the mass of our sun, is actively drawing material from its closest stellar companion, a star about 70% as massive as the sun. This star orbits the black hole every six and a half days at a distance much closer than Earth’s orbit around the sun. The second companion star, slightly more massive than the sun, orbits the pair every 70,000 years at a distance 3,500 times greater than that between Earth and the sun.
Kareem El-Badry, an astronomer at Caltech and co-author of the study, noted, “The triple system could not have survived if the black hole was born with the kick of a supernova explosion. This discovery provides strong evidence that some black holes form without an explosive event.”
This phenomenon, termed a “failed supernova,” suggests that the star’s core collapsed inward too quickly for a supernova to occur, resulting in an implosion rather than an explosion. The findings not only challenge existing models of stellar death but also have implications for understanding the evolution of black hole binaries.
“Many known binaries with black holes may have originated from triple systems like this one,” El-Badry added. “Over time, the black hole can consume one of its stellar companions, leaving behind a binary system.”
The discovery of V404 Cygni’s gentle origin provides astronomers with a unique laboratory to study black hole formation and the complex gravitational interactions in multi-star systems. As observations continue, this remarkable system may offer further insights into the life cycles of stars and the mysterious processes that govern our universe.
Reference(s):
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