Astronomers Discover the Closest Blackhole to Earth in Our Cosmic Backyard

Astronomers estimate that there are about 100 million black holes in the Milky Way galaxy alone. However, scientists spent years searching for the closest cosmic messy eater to our home planet. Astronomers recently used the International Gemini Observatory in Hawaii to discover the closest blackhole to Earth.

This is the first time astronomers are discovering a dormant stellar-mass black hole in our cosmic backyard. This black hole is located just 1600 light years away from Earth and scientists are hoping to use its existence in studying the evolution of binary systems.

Why this discovery marvels our scientists

Since there are about 100 million stellar-mass black holes in our home galaxy, astronomers earlier thought that none of them is this close to our solar system. But despite the millions of black holes in the Milky Way, scientists were only able to discover a few of them. The only confirmed black holes were spotted because they were active and shine so bright in X-rays as they eat cosmic materials from neighboring stellar companions.

Keep in mind that each stellar-mass black hole weighs between five to 100 times the mass of the Sun. This implies that these black holes cannot be compared with our sun in any way. After decades of searching for the closest black holes to Earth, Astronomers finally spotted this new stellar-mass black hole which they named Gaia BH1.

They deployed the Gemini North telescope in Hawai’i which is one of the twin telescopes of the International Gemini Observatory to make this fascinating discovery. These twin telescopes were operated by the NSF’s NOIRLab. Astronomers studied the newly discovered black hole and realize that it belongs to a dormant type with about 10 times more mass than the Sun.

It is located about 1600 light-years away in the constellation Ophiuchus. Gaia BH1 is three times closer to our home planet than the previous recorder holder, which is an X-ray binary black hole in the constellation of the Monoceros. While astronomers were studying a distant Sun-like star that orbits around the black hole at the same distance Earth orbits the Sun, they came up with this new discovery.

“Take the Solar System, put a black hole where the Sun is, and the Sun where the Earth is, and you get this system,” explained Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian and the Max Planck Institute for Astronomy. “While there have been many claimed detections of systems like this, almost all these discoveries have subsequently been refuted. This is the first unambiguous detection of a Sun-like star in a wide orbit around a stellar-mass black hole in our Galaxy.”

From this statement, you will realize that the few detected stellar-mass black hole were seen because of their energetic interactions with a neighboring star. When the material from the companion star moves toward the black hole, it will get to a state where it will become highly heated and produces powerful X-rays. Scientists have discovered that if a black hole is not consuming other materials within its path, it focuses on blending within its surroundings.

“I’ve been searching for dormant black holes for the last four years using a wide range of datasets and methods,” said El-Badry. “My previous attempts — as well as those of others — turned up a menagerie of binary systems that masquerade as black holes, but this is the first time the search has borne fruit.”

How the team discovered the closest blackhole to Earth in our cosmic backyard

Video Credit: T. Müller (MPIA), PanSTARRS DR1 (K. C. Chambers et al. 2016), ESA/Gaia/DPAC

The team of scientists that came up with this study previously analyzed the data obtained by the European Space Agency’s Gaia spacecraft and concluded that the system has the potential of hosting a black hole. Gaia spacecraft spent some moments capturing the minute irregularities in the star’s motion. These irregularities were caused by the gravity of an unidentified gigantic object.

However, El-Badry and his colleagues did not only rely on the data obtained by the spacecraft in coming up with this study. The team used the Gemini Multi-Object Spectrograph instrument on Gemini North in exploring the system even further to discover the new black hole. This powerful instrument measured the velocity of the companion star as it move around the black hole. In fact, the spectrograph instrument was sophisticated enough to give an exact measurement of the orbital period of the star around the black hole.

The team conducted follow-up observations to learn the orbital motions and masses of the two objects that made up the binary system. These follow-up observations enabled the team to learn that the central body of the black hole is about 10 times more massive than our Sun. The team was fascinated with the scientific data they obtained from this observation.

“Our Gemini follow-up observations confirmed beyond reasonable doubt that the binary contains a normal star and at least one dormant black hole,” El-Badry explained. “We could find no plausible astrophysical scenario that can explain the observed orbit of the system that doesn’t involve at least one black hole.”

The team did not depend only on Gemini North’s powerful instrument for this discovery, as they also explored Gemini’s sophistication to generate data on a short window.

“When we had the first indications that the system contained a black hole, we only had one week before the two objects were at the closest separation in their orbits. Measurements at this point are essential to make accurate mass estimates in a binary system,” said El-Badry. “Gemini’s ability to provide observations on a short timescale was critical to the project’s success. If we’d missed that narrow window, we would have had to wait another year.”

Why this Discovery of closest blackhole to earth still remains Marvels our Astronomers

Based on the latest models of the evolutions of binary systems created by astronomers, they are still finding it challenging to explain the science behind the peculiar configuration of the Gaia BH1 system and how it could have come into existence. Scientists assume that the system was initially made up of two stars.

However, one of the stars later turned into a newly spotted black hole. Based on the scientific observations conducted in this region, the star may have lived for only a few million years before transforming into a black hole. Astronomers are still struggling to determine how normal stars would have survived different evolution stages and share a binary system with a black hole. This new discovery will unlock a new study of understanding dormant black holes in binary systems.

“It is interesting that this system is not easily accommodated by standard binary evolution models,” concluded El-Badry. “It poses many questions about how this binary system was formed, as well as how many of these dormant black holes there are out there.”

NSF Gemini Program Officer Martin Still shared his view about this latest discovery.

“As part of a network of space- and ground-based observatories, Gemini North has not only provided strong evidence for the nearest black hole to date but also the first pristine black hole system, uncluttered by the usual hot gas interacting with the black hole,” said Martin Still. “While this potentially augurs future discoveries of the predicted dormant black hole population in our Galaxy, the observations also leave a mystery to be solved — despite a shared history with its exotic neighbor, why is the companion star in this binary system so normal?”


Scientific discoveries like this often improve our knowledge of astronomy. Scientists will continue to explore the data obtained from this observation to learn more about dormant black holes in a binary system. What do you think about this discovery?

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