WHAT MAKES A STAR STRANGE?
Most stars follow relatively predictable stages of stellar evolution. But some stellar objects exist under extraordinary conditions. They can rotate hundreds of times per second, possess magnetic fields trillions of times stronger than Earth's, or compress more than the mass of the Sun into a sphere only a few tens of kilometers across. These objects are among the most extreme laboratories for testing physics in the Universe.
NEUTRON STARS
A neutron star can form when the core of a massive star collapses during a supernova. The remaining matter is compressed to an extraordinary density. A typical neutron star has a radius of only about 10–15 kilometers while containing roughly 1–2 times the mass of the Sun. A teaspoon of neutron-star matter would weigh an enormous amount on Earth.
PULSARS
Some neutron stars rotate rapidly and emit beams of electromagnetic radiation from their magnetic poles. If one of these beams sweeps across Earth, astronomers can detect regular pulses of radiation. These objects are called pulsars. Some pulsars rotate hundreds of times per second, making them among the most precise natural clocks known.
MAGNETARS
Magnetars are neutron stars with extraordinarily powerful magnetic fields. Their magnetic fields can be trillions of times stronger than Earth's magnetic field. Magnetars can produce powerful bursts of X-rays and gamma rays when their crusts shift or their magnetic fields undergo violent changes.