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Astronomers discovered Gaia BH3, a massive black hole near Earth, the third found by ESA's Gaia telescope since 2013.

About Black Holes Close to Earth

Black holes are mysterious and powerful objects in space. They’re so dense that not even light can escape their gravity.

Astronomers discovered three black holes near Earth using the Gaia spacecraft, a European Space Agency (ESA) mission.  

How Astronomers discovered these Black Holes?

Gaia is a space telescope that has been mapping the Milky Way since 2013. It tracks the movements of billions of stars. Sometimes, a star appears to orbit “empty space,” which is a clue that a black hole might be hiding there.

Ground-based telescopes measure how light from these stars shifts due to the Doppler effect. This helps astronomers figure out how fast the star is moving and whether it’s orbiting something invisible—like a black hole.

By combining Gaia’s data with Kepler’s third law (which relates orbital speed to mass), astronomers can calculate the mass of the invisible object. If it’s too massive to be a neutron star, it must be a black hole.

The Three Black Holes Discovered

1. Gaia BH1:
   • • Distance: 1,560 light-years from Earth.
     • Mass: About 9 times the mass of the Sun.
     • Discovery: Found in 2022, it’s the closest known black hole to Earth.
2. Gaia BH2:
   • • Distance: Slightly farther than BH1.
     • Mass: Also around 9 times the Sun’s mass.
     • Discovery: Announced in early 2023.
3. Gaia BH3:
   • • Distance: About 2,000 light-years away in the constellation Aquila.
     • Mass: A whopping 33 times the Sun’s mass—the largest stellar-mass black hole found in the Milky Way so far.
     • Discovery: Reported in April 2024.

Why Is Gaia BH3 Special?

• Size: At 33 solar masses, it’s much bigger than most black holes in our galaxy. For comparison, the previous record-holder, Cygnus X-1, is only 21 solar masses.
• Location: It’s in the outer part of the Milky Way, which is unusual. Most black holes are found closer to the galaxy’s center.
• Age: The star orbiting BH3 is very old, suggesting the black hole formed early in the universe’s history.
• Passive Nature: Unlike some black holes, BH3 isn’t actively pulling in matter or emitting X-rays. This makes it harder to detect but also gives scientists a chance to study a “quiet” black hole.

Gaia Project

The Gaia project is operated by the European Space Agency (ESA).

It is a space mission dedicated to creating an extremely precise 3D map of our Milky Way galaxy by surveying and meticulously measuring the positions, distances, motions, and brightness of over a billion stars.

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Source: 

THE HINDU