Starship Asterisk*

This close-up view of the center of the Andromeda galaxy, taken by NASA’s retired Spitzer Space Telescope, is annotated with blue dotted lines to highlight the path of two dust streams flowing toward the supermassive black hole at the galaxy’s center (indicated by a big dot in the middle).Credit: NASA/JPL-Caltech

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Data from NASA's retired Spitzer Space Telescope has given scientists new insights into why some supermassive black holes shine differently than others.

In images from NASA's retired Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the heart of the Andromeda galaxy. It turns out these streams can help explain how black holes billions of times the mass of our Sun satiate their big appetites but remain "quiet" eaters.

As supermassive black holes gobble up gas and dust, the material gets heated up just before it falls in, creating incredible light shows — sometimes brighter than an entire galaxy full of stars. When the material is consumed in clumps of different sizes, the brightness of the black hole fluctuates.

But the black holes at the center of the Milky Way (Earth's home galaxy) and Andromeda (one of our nearest galactic neighbors) are among the quietest eaters in the universe. What little light they emit does not vary significantly in brightness, suggesting they are consuming a small but steady flow of food, rather than large clumps. The streams approach the black hole little by little, and in a spiral, similar to the way the water swirls down a drain.
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