Welcome to the third installment of Astronomy Club's exclusive column, A World Outside the Globe! This week, read on for an exploration of universal mysteries by Jessica Dong '23.
What Is a Black Hole?
A black hole is an astronomical object in space where gravity pulls so much that even light cannot get out.
Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of galaxy M87, outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon.
Credits: Event Horizon Telescope collaboration et al.
Formation of a Black Hole
A black hole is formed upon the death of a massive star.
This complicates into the matter of stellar evolution. When a massive star (with a mass over 25 solar mass) exhausts its internal thermonuclear fuels, its core becomes unstable and collapses upon itself. As it overcomes the degenerate neutron pressure, the dying star’s extensive mass resolves into a point of singularity — to a black hole. Its gravity then becomes so massive that the escape velocity of the black hole exceeds the speed of light; in other worlds, beyond the event horizon, nothing can escape from its grip.
Peering through the darkness
Black holes’ gravitational pull swallows all light; therefore, astronomers cannot spot them like they normally do for other cosmic bodies across the universe. But there are a few key elements that hint at its presence - for example, astronomers can use the erratic movements of stars influenced by its gravity to infer the presence of the lurking black hole.
Black holes are also massive star-eaters. As they “digest” surrounding stars, their massive gravitational and magnetic forces heat up the infalling gas and dust, causing them to emit radiation, which can then be detected.
Citations:
“Black Hole.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., www.britannica.com/science/black-hole.
cdn.britannica.com/50/62750-050-C12B4D5F/evolution.jpg
www.nasa.gov/sites/default/files/styles/full_width/public/thumbnails/image/blackhole.png?itok=THJrwcHP.
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