A pulsar

[saturno2]

A pulsar is a neutron star. It has small diameter and high density.
But the most incredible is his speed. For example, the Crab Pulsar
has 25 km of diameter and rotates 30 times per second.
That is 1,800 times per minute.
A standard electric motor rotates 1,800 times per minute.
How, a pulsar, an astronomical object so dense, so "heavy"
can rotate at high speed?

[Beyond]

MAGIC.

[neufer]

the Crab Pulsar has 25 m of diameter

• The Crab Pulsar ~ 25 km of diameter.

[stephen63]

Listen to these pulsars. It puts it in perspective. All of that mass spinning so fast. Anything else would probably fly apart.

http://www.astro.cornell.edu/~deneva/ps ... sounds.htm

[Ann]

Click to view full size image

Source: http://www.astronomynotes.com/evolutn/s12.htm

Saturno2, do you ever watch figure skating? If so, have you noticed what figure skaters do to speed up their own rotation? First they hold out their arms from their bodies and spin slowly. Then they hold their arms close to their bodies and spin faster. Effectively, they make themselves smaller, and the rotation speed that they had when they were "large" (by holding out their arms) increases when they make themselves "small".

Click to view full size image

Source: http://www.ucolick.org/~bolte/AY4_00/we ... lsars.html

All known stars rotate. A pulsar is the ultra-massive core of a massive star. In the picture on the left, you can compare the size of the Sun with the size of a white dwarf and the size of a neutron star. A pulsar is a fast-rotating neutron star that is very gradually slowing down, emitting strong pulses of energy as it does so.

Pulsars are the smallest of all stars. They are also the densest of all stars, and therefore they are extremely good at withstanding the centrifugal force that would make less dense stars fly apart if they rotated as fast as pulsars.

The page from which I took the picture of the relative sizes of the Sun, the white dwarf and the neutron star, it says:

The Sun rotates at 1 rev per 30 days. Compress it to 10 km and conserve angular momentum, it would spin up to 1890 revolutions/second (and fly apart).

So a rotation speed of 1890 revolutions per second would probably be too much even for a pulsar, but a rotation speed of 30 revolutions per second is not faster than these ultra-dense stellar corpses can withstand.

Ann

[saturno2]

Thanks, Neufer
The Crab Pulsar has 25 Km of diameter
You are right

[saturno2]

Thanks
Ann and stephen63 for your important notes.

[saturno2]

A baryon is a subatomic particle composed of 3 quarks.
There are 2 types of baryons: protons and neutrons.
A neutron is a baryon has 3 quarks: 2 called "dawn" and 1 called "up"
Well. In a pulsar must imagine these quarks highly compressed, leaving no vacuum space for to have high density .

[rstevenson]

... In a pulsar must imagine these quarks highly compressed, leaving no vacuum space for to have high density .

The structure of neutron stars is quite complex and varied. For example, they have outer and inner crusts, a deeper layer of more or less uniform nuclear matter, and a core of not well understood properties. In those upper layers there can be a lattice of heavy nuclei, degenerate electron gases, superfluid neutron gases, and other exotic forms of matter. And there can be phase changes occurring too. (More than that I cannot say, since I'm already speaking well above my pay grade. )

Rob

[saturno2]

Pulsars have different speeds of rotation from 1 time per 9.4 seconds to 716 times
per second.
A " millisecond " pulsar rotate 1,000 times or more per second.
I can not imagine an object spinning so fast.
A point in the ecuador of this type of pulsar has a linear velocity of
78,500 km/ sec ( diameter of pulsar 25 km )
78,500 km/ sec is 1/ 3.8 of the light speed

[Ann]

... In a pulsar must imagine these quarks highly compressed, leaving no vacuum space for to have high density .

The structure of neutron stars is quite complex and varied. For example, they have outer and inner crusts, a deeper layer of more or less uniform nuclear matter, and a core of not well understood properties. In those upper layers there can be a lattice of heavy nuclei, degenerate electron gases, superfluid neutron gases, and other exotic forms of matter. And there can be phase changes occurring too. (More than that I cannot say, since I'm already speaking well above my pay grade. )

Rob

Thanks for the info, Rob, and for your wonderfully self-deprecating way of putting it!

Ann

[rstevenson]

Thanks for the info, Rob, and for your wonderfully self-deprecating way of putting it!

To mis-quote Churchill, "I'm a modest man with much to be modest about."

Rob

[saturno2]

I include myself in the group of Rob ( amateur astronomers) but we want
to know more.
In my area I have no facility to study Astronomy, only Internet.
Well. I think if we ( the amateurs) have an idea of how it work a pulsar,
we can try understand something more difficult: a black hole.

[saturno2]

The story of pulsars hides an injustice.
Joselyn Bell, a doctoral student, discovered the first pulsar.
But, Antony Hewish, his research fellow, received the award Nobel of
Physics at 1974.
Joselyn did not receive anything for to be only a " student"
I think that knowledge is for all, not " only " for academic doctors

[saturno2]

Pulsars develop strong magnetic fields, wich can became large magnetic fields
( magneters)
Well. What is the maximum diameters of these magnetic fields of the
pulsars?