Rotation Rates
The following image illustrates the pulsation of the first pulsar discovered, CP 1919.
(The designation "CP" standing for "Cambridge Pulsar"; this pulsar is also called
PSR 1919+21 in the naming system described in the right panel). It has a period of
just over 1.33 seconds.
More generally, pulsar periods range from about 4.3
seconds for the slowest to 16 milliseconds (0.0016 seconds)
for the fastest. Since pulsars are slowing down with time (see below) as they emit energy both in
electromagnetic and gravitational waves, we may expect that the fastest pulsars are the youngest.
For
example, the Crab Pulsar is
young (less than 1000 years), and pulses 30 times a second. However, as we
shall see below, this reasoning breaks down for the pulsars with millisecond periods, which cannot be as young
as their periods would suggest.
Pulsar Sounds
Since pulsars pulse in the RF part of the spectrum, it is possible to "listen" to them by connecting the
amplified signal from the radio telescope to a radio speaker.
The adjacent control panel allows you to access
streaming sound files for three pulsars of quite different periods:
|
PSR 0329+54
has a pulse period of about 0.715 seconds.
|
|
PSR 0833-45
(Vela Pulsar) has a period of 89.3
milliseconds.
|
|
PSR 1937+21
is a very fast pulsar, with a period
of 1.56 milliseconds that corresponds to 640 revolutions per second.
|
For the first two you can hear the pulses clearly. For the last one the period is so short that
the pulses blend into a continuous whine, like a 15-kilometer-wide kitchen blender spinning at
640 revolutions per second!
