Pulsars are the collapsed, “zombie-like” cores of massive stars that have undergone supernova explosions. According to Saint Anselm College astronomy professor Nicole Gugliucci, these objects consist almost entirely of neutrons and emit beams of electromagnetic radiation that sweep across space, creating a “lighthouse” effect visible to observers on Earth.
How do pulsars create a “lighthouse effect”?
The visible pulsing of a pulsar is a result of its specific orientation in space. Gugliucci explains that a pulsar’s magnetic axes are typically misaligned with its rotation axes. This misalignment causes beams of electromagnetic radiation to sweep out across space in a regular pattern.
Earth-based observers do not see a continuous stream of light. Instead, they detect a pulsed signal only when these radiation beams point directly toward our planet. This mechanism functions similarly to a rotating lighthouse beacon sweeping across the ocean.
While a pulsar may only be about 20 kilometers (12 miles) in diameter, it retains a mass approximately 1.35 times that of the sun.
What causes the extreme rotation speed of pulsars?
Pulsars can spin at incredible velocities, reaching speeds of up to one rotation every 1,000th of a second. This rapid rotation is a direct consequence of the star’s collapse during a supernova.
Gugliucci compares this physical process to an ice skater performing a spin. When an ice skater pulls their arms inward, their rotation speed increases. Similarly, as massive stars form from gas clouds and subsequently collapse, the resulting remnant spins faster and faster as its physical dimensions decrease.
How dense is the core of a pulsar?
The composition of a pulsar is defined by extreme density. Following the death of a massive star, the remaining core is made almost entirely of neutrons. These particles are packed together so tightly that the density of the pulsar exceeds that of atomic nuclei.
This density allows a relatively small object—roughly 20 kilometers in diameter—to maintain a mass significantly greater than that of our sun. This concentration of matter is what distinguishes these remnants from other celestial bodies.
Quick Facts: Pulsar Physical Properties
- Composition: Almost entirely neutrons
- Diameter: Approximately 20 kilometers (12 miles)
- Mass: Roughly 1.35 times the mass of the sun
- Rotation Speed: Up to a 1000th of a second per rotation
Frequently Asked Questions
What is a pulsar made of?
Pulsars consist almost entirely of neutrons packed at a density higher than that of atomic nuclei.
Why do pulsars appear to pulse?
They appear to pulse because their magnetic axes are misaligned with their rotation axes, causing radiation beams to sweep past Earth like a lighthouse beam.
How do pulsars form?
Pulsars form from the collapsed cores of massive stars that have ended their life cycles in supernova explosions.
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