# How strong are pulsar winds?

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## Summary:

Question about the strength of pulsar winds.
I keep reading on the internet that pulsar winds can travel at relativistic speeds. If so, how strong are these pulsar winds? What kind of force would they carry?

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jim mcnamara
Mentor
To help us out, could you please give an example of where you read this?
Like: read this in an article in the May edition of Science Alert - or whatever.

Just so we agree what we are talking about:
Rapidly rotating neutron stars are called pulsars. The crab nebula is a pulsar wind nebula, for example.
And strong magnetic fields can accelerate charged particles (like ionized gas atoms) to very high velocities.

Here is a more advanced look:
https://arxiv.org/abs/1001.1749

Staff Emeritus
2019 Award
how strong are these pulsar winds?
If I said "six, maybe eight" that probably wouldn't satisfy you. So what units are you thinking of?

russ_watters
To help us out, could you please give an example of where you read this?
Like: read this in an article in the May edition of Science Alert - or whatever.

Just so we agree what we are talking about:
Rapidly rotating neutron stars are called pulsars. The crab nebula is a pulsar wind nebula, for example.
And strong magnetic fields can accelerate charged particles (like ionized gas atoms) to very high velocities.

Here is a more advanced look:
https://arxiv.org/abs/1001.1749
I read it on several places, but...

https://www.cfa.harvard.edu/news/su201643
"A pulsar also has a wind, and charged particles, sometimes accelerated to near the speed of light, form a nebula around the pulsar: "

If I said "six, maybe eight" that probably wouldn't satisfy you. So what units are you thinking of?
Maybe kilo or even mega units would do.

Staff Emeritus
2019 Award
Maybe kilo or even mega units would do.
OK, six kilos to eight megas. See the problem? What units are you looking for?

phinds
OK, six kilos to eight megas. See the problem? What units are you looking for?
Units of force, perhaps.

Staff Emeritus
2019 Award
Force on what? Even with plain old Earthbound wind wind the force on different objects is different. The force on a sail can move a giant ship, yet we can overcome it when walking.

I think you need to think through your question better. As it stands, I don't think your question is answerable.

phinds
Force on what? Even with plain old Earthbound wind wind the force on different objects is different. The force on a sail can move a giant ship, yet we can overcome it when walking.

I think you need to think through your question better. As it stands, I don't think your question is answerable.
I thought it was. How about this? What kind of effects can a pulsar wind cause in terms of force in Newtons? I mean, what can they do when they come into contact with other bodies in space at such high speeds?

phinds
Gold Member
2019 Award
I thought it was. How about this? What kind of effects can a pulsar wind cause in terms of force in Newtons? I mean, what can they do when they come into contact with other bodies in space at such high speeds?
WHAT "other bodies" ? As Vanadium has repeatedly pointed out, your question is too vague. Do you think the effect they would have on a solar sail would be the same as the effect they would have small ball bearing?

I understand that you think you have asked a very simple question and that it should have a simple answer. What you have actually asked is "how high is up?"

WHAT "other bodies" ? As Vanadium keeps pointing out, your question is too vague. Do you think the effect they would have on a solar sail would be the same as the effect they would have small ball bearing?
I meant other bodies in space. Like planets, comets, asteroids. Would pulsar winds, made of charged particles moving near the speed of light, have any effect on these bodies? I was never talking about anything on Earth.

phinds
Gold Member
2019 Award
I meant other bodies in space.
But you didn't SAY that, you just said "other bodies". My answer was regarding bodies in space.

You simple continue to realize that you seem unable to ask an answerable question.

Now, you may think that you HAVE finally now that you have specified what bodies you are talking about, but you haven't. How big a body? How far away from the source.

I'm out ...

EDIT: but before I go, I want to make sure you understand: we are not giving you a hard time just for the hell of it, we are trying to get you to learn how to ask an answerable question.

jim mcnamara
But you didn't SAY that, you just said "other bodies". My answer was regarding bodies in space.

You simple continue to realize that you seem unable to ask an answerable question.

Now, you may think that you HAVE finally now that you have specified what bodies you are talking about, but you haven't. How big a body? How far away from the source.

I'm out ...
I said that because I thought it would be clear that the other bodies would be those in space. Pulsar winds are space winds, after all. What more do you want? It's not like they can be produced on Earth.

That said, let us say the body is comet sized, and is very close to the source of the pulsar wind. How strong is it then?

I didn't come here to be mocked, you know.

Staff Emeritus
2019 Award
Nobody is mocking you. But your question is essentially "how long is a piece of string". Furthermore, your PM suggests that you think it is somehow our fault that you asked an ambiguous question and that it is our responsibility to fix it.

Your question is no more and no less answerable than "what is the force of the sun on objects in space".

Like phinds, I'm out.

Nobody is mocking you. But your question is essentially "how long is a piece of string". Furthermore, your PM suggests that you think it is somehow our fault that you asked an ambiguous question and that it is our responsibility to fix it.

Your question is no more and no less answerable than "what is the force of the sun on objects in space".

Like phinds, I'm out.
I gave the details you asked for, and this is what I get? How is asking about the strength of pulsar winds that ambiguous, anyway?

I think he wants you guys to assume the size and distance of the object and other parameters not already specified. Could you guys answer if the object is say the earth at a distance of .5AU around a pulsar of 20km in diameter with a mass of 1.4 times the mass of our sun. Alternatively Sundown you could use my phrasing as a basis for a better question. I would add more information but I got to go. Just add as much detail as you can think of.

russ_watters and berkeman
I think he wants you guys to assume the size and distance of the object and other parameters not already specified. Could you guys answer if the object is say the earth at a distance of .5AU around a pulsar of 20km in diameter with a mass of 1.4 times the mass of our sun. Alternatively Sundown you could use my phrasing as a basis for a better question. I would add more information but I got to go. Just add as much detail as you can think of.
Thanks Stephen, though I admit, I could have worded the question better. That said, the size and distance of the object, as well as the other parameters (which ones, by the way?) is what I wanted the others to assume. That said, maybe I should have used numbers and maybe something else when asking? Maybe that would have helped?

Some other perameters could be the density of pulsar winds, I do not know what that could be set to. Additionally are there other objects in the area, I suggest you assume there are none. For the sake of simplicity you could assume the pulsar is the one in this website
https://en.m.wikipedia.org/wiki/Crab_PulsarAnother perameter might be the velocity of the winds but I do not know what that would be. Unfortunately, I know very little about astronomy so I cannot help with answering your question but I might be able to direct you to formulate a better question. Additionally direction would matter, the rotation of the pulsar might affect it (I don’t know if that’s true since I know very little) How about those who know more than I do answer (or point in the right direction) what velocity might a pulsar wind around the crab pulsar be at .5AU, assuming the wind is orbiting in a perfect circle in the same direction of the crab pulsar’s rotation? Additionally, what density could the wind have assuming it has an “average” density. Next if the Earth was orbiting in that same exact orbit except in the opposite direction what would happen to the earth and how quickly?

russ_watters
Mentor
Let's see if I can focus it even more:

Solar radiation pressure at Earth's distance from the sun is about 4.5 microPascals (N/m2).

What is the radiation pressure of a pulsar at a distance equal to Earth's distance from the Sun? (say, the Crab Nebula pulsar).

This gives us a useful context for a comparison.

berkeman and jim mcnamara
PeterDonis
Mentor
2019 Award
Solar radiation pressure at Earth's distance from the sun is about 4.5 microPascals (N/m2).
I'm not sure this is quite the analogy to use, since the OP is talking about "pulsar winds", which would be analogous to the solar wind. According to Wikipedia [1], the pressure of the solar wind is about 1 to 6 nanopascals.

[1] https://en.wikipedia.org/wiki/Solar_wind

russ_watters
russ_watters
Mentor
I'm not sure this is quite the analogy to use, since the OP is talking about "pulsar winds", which would be analogous to the solar wind. According to Wikipedia [1], the pressure of the solar wind is about 1 to 6 nanopascals.

[1] https://en.wikipedia.org/wiki/Solar_wind
Carp, you're right!