Neutron Stars and Pulsars The discovery of neutron stars as pulsars (1968): an accomplishment of radio astronomy

Pulsating Radio Sources (Pulsars) Radio sources that turned off and on (transparency) Periods extremely precise (like precision clocks). Example, 0329+54 has P=0.71451866398 seconds. Every digit is significant Nature of these objects figured out within a year of their discovery.

Pulsars as rotating neutrons stars The pulsar period is the rotation period (that’s what makes them such precise clocks) demo

Pulsars as massive star remnants: the Crab Nebula Pulsar X-ray picture (Chandra spacecraft)

http://chandra. harvard. edu/resources/animations/crab_timelapse_sm http://chandra.harvard.edu/resources/animations/crab_timelapse_sm.mov

Current status: more than 1500 radio pulsars known

Summary of Pulsar Properties Periods from 5 sec to 1.6 milliseconds All pulsars slow down with time; lifetime is about 10 million years In addition to radio pulsars, other neutron stars seen in x-rays

Demo: the sounds of pulsars

In less than 40 years, neutron stars have gone from esoteric predictions of theoretical physics to a class of known astronomical objects with more than 1500 members. They are out there in the sky and they are associated with the outcome of massive star evolution.