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In the book "Horizons: exploring the universe-Cengage learning (2018)", page 224, it states that:

When a pulsar first forms, it is spinning fast, perhaps a hundred times a second. The energy it radiates into space comes from its energy of rotation, so as it blasts beams of radiation outward, its rotation slows.

The average pulsar is apparently only a few million years old, and the oldest are about 10 million years old. Presumably, older neutron stars rotate too slowly to generate detectable radio beams.

So will pulsars eventually stop spinning due to the energy it radiates into space? As there are no extra energy sources that give pulsars to spin. And I know the space is basically empty space, but will air resistance be a factor that slows the spinning of pulsars or other stars?

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Yes, eventually everything will indeed stop spinning.

When a pulsar is created, it retains almost all of the previous star's angular momentum, while losing most of its size. This is why they spin so fast and pulsate electromagnetic radiation.

As they lose energy and momentum overtime their rotation will slow down; but even sooner, they will lose the radio pulsating mechanism that makes them pulsars in the first place.

This "turnoff" point is actually shorter than one might expect: a normal pulsar will stop pulsating just after a few hundred million years (most of the pulsars that have been born up to now are no longer pulsating).

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  • $\begingroup$ So does the air resistance has to do with the slow down of stars? $\endgroup$ Aug 17 '21 at 9:44
  • $\begingroup$ Why do you think there would be air near a neutron star? There is no air in space. I mean air (merriam-webster.com/dictionary/air) as the mixture of gases that surround Earth. When you say air do you mean something else? $\endgroup$
    – Prallax
    Aug 17 '21 at 10:14
  • $\begingroup$ @Prallax How about interstellar medium? As they are composed of gas, and I'm not just ask for pulsars, but all stars as well, maybe the title I made is a little bit misleading. $\endgroup$ Aug 17 '21 at 10:27
  • $\begingroup$ @JacktheRanger ok, with "interstellar medium" it makes much more sense to me. I suggest you write another question instead of editing this one, since there are already two answers that talk about pulsars $\endgroup$
    – Prallax
    Aug 17 '21 at 10:39
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As long as pulsars are usually 'high rate' emitting neutron stars (including visible light, near infrared, ultraviolet, X-rays, and gamma rays) the emission will eventually decrease electromagnetic radiation. Eventually, pulsar-neutron star will become non-pulsating neutron star.

Wikipedia:

On the other hand, neutron star rotational speeds can increase (spin up process). Sometimes neutron stars absorb orbiting matter from companion stars, increasing the rotation rate.

The most rapidly rotating neutron stars currently known are: PSR J1748-2446ad, rotates at 716 rotations per second; XTE J1739-285, 1122 rotations a second.

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