Pulsars

Pulsars are quickly rotating neutron stars --- under something like 10 miles in size, rotating with periods less than about 1 second, made up of neutrons (plus some other stuff). A neutron star is apparently the product of a supernova explosion. It's the leftover core of the star that went supernova. The core collapsed and spun up (like an ice skater pulling her arms in).

This is not well understood, but its thought the process has to do with the large magnetic field at the surface of the neutron star. The radio pulses (and sometimes the pulses are observed in other parts of the spectrum, like visible light, for example), apparently arise near the polar cap of the magnetic field and are beamed out like a light house beacon. As the beacon sweeps across our position, we detect the "pulse."

If you mean in the sense of radioactive elements like Uranium --- no.

The time between pulses for a given pulsar might be about 1 second. Others have smaller times. The smallest approach about 1 millisecond. On the other hand, the actual pulses are smaller in length than the time between the pulses.

The time between pulses for a given pulsar might be about 1 second. Others have smaller times. The smallest approach about 1 millisecond. On the other hand, the actual pulses are smaller in length than the time between the pulses.

It slows down, eventually, and the pulses die out as a result.

Yes and no. Neutron stars are very nearly dense enough to have become black holes, and a supermassive black hole is thought to lie at the center of, and be the energy source for, a quasar. It is also possible the structure, and rotation, of the magnetic field around a rotating black hole at the center of a quasar is similar to that around a pulsar --- and would therefore be responsible for some of the effects observed for quasars.

No. They may be responsible for some of the cosmic rays we experience at Earth, but their effect on any one person is small.

In 1967. It was discovered "by accident" during an radio astronomy observing program designed to look for "twinkling" radio sources.

It's just a pulsar with a millisecond pulse period --- the time between pulses is about that short. There are quite a few known nowadays. They apparently reside in binary star systems, and the infall of material from the nearby star, on to the spinning neutron star, may have spun up the neutron star to give it its millisecond rotation period.