The Hubble Space Telescope captured a new image, and it looks like all the other ones it takes. It’s stunning, as usual, and shows several galaxies. The one I’m going to talk about is NGC 4889. It’s a large elliptical galaxy parked about 300 million light-years away in the Coma Cluster.
NGC 4889 is the largest and brightest galaxy in the image.
The galaxy doesn’t look all that unique from the outside, but it’s what lies at its center that has astronomers buzzing. A gigantic black hole. We’re talking about a black hole that is 21 billion times the mass of the sun. The event horizon, you know the part where light can’t even escape, has a diameter of 130 billion kilometers.
The press release accompanying the image helps give us some perspective. A diameter of 130 billion kilometers is nearly 15 times the diameter of Neptune’s orbit from the sun. So yeah, it’s big.
And the black hole at the center of our galaxy (the Milky Way) pales in comparison. It’s about 4 million times the mass of the sun with an event horizon of just one fifth the orbit of Mercury.
The center of NGC 4889 probably isn’t the most friendly of areas, right? Actually, astronomers believe the black hole is done feasting on NGC 4889. “The environment within the galaxy is now so peaceful that stars are forming from its remaining gas and orbiting undisturbed around the black hole,” reads a statement.
But it wasn’t always this way. When the black hole was in the middle of its all-you-can-eat buffet of NGC 4889, astronomers would have classified NGC 4889 as a quasar. Massive, energetic jets would have emitted unprecedented amounts of energy. Astronomers estimate it could have been up to a thousand times the energy output of the Milky Way.
How do you find a black hole?
How do you find something that not even light can escape from? There are a couple of ways. When a black hole is active, large amounts of gas are sucked in. This gas is heated up as it gets closer to the black hole and starts emitting X-rays and radio waves. Astronomers can find black holes by looking for bright areas of X-rays and radio waves.
But, this supermassive black hole is dormant. How do we find this type of black hole? Astronomers can also them by studying the stars moving around it. By studying how quickly a star moves, astronomers can figure out the mass of the object it’s orbiting. In this case, a large black hole.
Image credits: NASA/ESA