Firestorm: Weather on a Neutron Star
by Steven Whitt
Imagine yourself in a sea of molten iron. A cloud of superhot gas spirals overhead. Moments later, that same cloud explodes with the fury of billions upon billions of hydrogen bombs. The explosion drives the molten sea into a frenzy, stirring up storm waves that will endure for 300 “days.”
What you've just witnessed, according to Dr. Jeremy Heyl of the Harvard-Smithsonian Center for Astrophysics, is some of the most extreme weather in the universe—weather that occurs at the surface of a neutron star.
A neutron star is the squashed remains of a star that has blown itself apart in a supernova explosion. What's left is a hot, smooth ball the size of a city, but with the mass of our sun. Neutron stars are so squashed (or dense, as a scientist would say) that a golf ball-size chunk would weigh as much as a mountain.
Like other stars, neutron stars spin. But like an ice skater pulling in her arms while twirling, a neutron star spins faster and faster as it squashes itself smaller and smaller. A neutron star can spin (or rotate) hundreds of times every second, making the neutron star “day” short indeed.
Now imagine another, more ordinary star (like our sun) in orbit with a neutron star. Scientists call this a double star, or binary, system. Like a great cosmic vacuum cleaner, the neutron star pulls gas from the surface of its neighbor. This stolen cloud of gas spirals toward the neutron star, and then explodes in a nuclear fusion reaction—like the reactions that power hydrogen bombs, yet inconceivably larger.
The waves made by the explosion take around 300 rotations of the neutron star (300 “days”) to spread across its surface. The way these waves spread is amazingly similar to the way large-scale weather systems—such as El Niño—spread on Earth. Like neutron star weather systems, El Niño takes about 300 Earth rotations (our “days”) to develop, grow, and disappear. “Whether on a neutron star rotating 300 times a second, or on Earth rotating once every day,” says Dr. Heyl, “these weather systems are governed by the same physics.”
Keep in mind that these neutron star weather patterns occur in a fraction of a second of Earth time. So if you don't like the weather on a neutron star, just hang around. In the blink of an eye, it'll change.
- El Niño:
- A disruption of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe, including increased rainfall across the southern tier of the United States.
- What is a binary system? What happens in a binary system?
[anno: A binary system is a neutron star in orbit with a regular star, like our sun. In a binary system, the neutron star pulls gas off of the other star. The gas powers explosions on the neutron star's surface.]
- Why do you think that the gas flows in a particular direction in a binary system?
[anno: Since a neutron star is much denser than a regular star, it probably has a greater gravitational pull than a regular star. Therefore, it pulls the gas of a regular star toward itself.]
- What would happen if scientists could harness the energy produced by a neutron star?
[anno: Answers may vary but could include that if the energy of a neutron star could be harnessed, we might not have anymore fuel concerns in the world. Students might also suggest that harnessing the energy of a neutron star might make space travel easier.]