Astronomers discover the closest black hole to Earth

Nov. 4 () –

Astronomers have detected the closest black hole to Earth, just 1,600 light years away, using the Gemini North telescope, located in Hawaii.

This is the first detection of a stellar-mass black hole in the Milky Way, whose proximity offers a unique study target to advance understanding of the evolution of binary systems. reports in a statement NoirLabwhich operates the telescope.

Black holes are the most extreme objects in the universe. Supermassive versions of these unimaginably dense astronomical objects may lie at the center of the largest galaxies. However, stellar-mass black holes, weighing about five to 100 times the mass of the Sun, are much more common in the universe. with an estimated number of them around 100 million in the Milky Way alone.

However, only a few have been confirmed to date, almost all of which are active, meaning that they “glow” brightly in X-rays as they consume material from a nearby stellar companion. unlike dormant black holes that don’t, like the newly discovered one.

Astronomers have named this dormant black hole BH1. It weighs about 10 times the mass of the Sun and is located in the constellation Ophiuchus. At 1,600 light years, it is three times closer to our planet than the previous recordan X-ray binary located in the constellation Monoceros.

The new discovery was made possible by precise observations of the motion of the black hole’s companion, a Sun-like star that orbits the Sun at roughly the same distance as Earth from the Sun.

The team originally identified that the system potentially harbored a black hole, by analyzing data from the European Space Agency’s Gaia space probe, which had captured the tiny irregularities in the star’s motion caused by the gravity of an invisible, massive object.

To explore the system in greater detail, Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian and the Max Planck Institute for Astronomy, and his team made follow-up observations using the Multi-Object Spectrograph instrument on Gemini North, which were crucial in allowing the team to identify the central body as a black hole about 10 times more massive than our Sun.

“Our follow-up observations with Gemini confirmed beyond reasonable doubt that the binary system contains a normal star and at least one dormant black hole,” El-Badry explained in a statement.

The team relied not only on Gemini North’s exceptional observational capabilities, but also on Gemini’s ability to provide data on a tight schedule, as the team had a short window of time to make their follow-up observations.

“When we had the first indications that the system contained a black hole, we only had a week before the two objects were at the closest approach of their orbits. Measurements at this point are essential for making accurate mass estimates in a system.” binary, so Gemini’s ability to provide fast-response observations was critical to the project’s success. If we missed that narrow window, we would be forced to wait another yearEl-Badry said.

Astronomers’ current models of the evolution of binary systems cannot fully explain how the peculiar configuration of the Gaia BH1 system came to be, because the original star that later became this black hole, should have been at least 20 times more massive than our Sun.

This means that it would have lived only a few million years. If both stars formed at the same time, this massive star would have rapidly become a supergiant, inflating and engulfing the other star before it had time to become a proper main-sequence star. which burns hydrogen just like our Sun.

It’s not entirely clear how the solar-mass star survived that episode, ending up an apparently normal star, as observations indicate. All the theoretical models that allow this survival predict that the solar-mass star it should be in a much tighter orbit than is actually observed.

This could indicate that there are important gaps in our understanding of the formation and evolution of black holes in binary systems, and suggests the existence of a still unexplored population of dormant black holes in binary systems.