A Question About Pulsars

[ThiccRocketScientist]

            Recently, I have been crafting a cinematic-movie style Kerbal series called Kerbalkind. I have been longing for a good plot, or cool focus on a part of science that hasn't been explored much; instead of just planets something like black holes or wormholes. However, I thought a pulsar would be pretty awesome.

 

         So as for the science,

1) Do Pulsars have a low enough radius and high enough mass so that General Relativity is noticeable?

2) Could a Pulsar orbit Kerbin far away (Taking account for being 10x smaller) or would it just completely wreck the system?

 

Thanks,

John

 

[YNM]

Because of the whole scaling problems when coming to the game (body mass is about 1% real mass while scales are around 64%), I'm going to talk this in real scale (let's say, RSS).

1) Yes. More so on the surface - you can actually look at both poles from one vantage point.

2) Well, a pulsar (rapidly rotating neutron star) is up to three times the mass of Sun - so in any case, the central star would start to make a binary orbit with the pulsar. Also, the problem with a pulsar is it's radiation.

[ThiccRocketScientist]

10 minutes ago, YNM said:

Because of the whole scaling problems when coming to the game (body mass is about 1% real mass while scales are around 64%), I'm going to talk this in real scale (let's say, RSS).

1) Yes. More so on the surface - you can actually look at both poles from one vantage point.

2) Well, a pulsar (rapidly rotating neutron star) is up to three times the mass of Sun - so in any case, the central star would start to make a binary orbit with the pulsar. Also, the problem with a pulsar is it's radiation.

The relativity factor I like as an original idea for the series; I don't think any space movie has ever used a Pulsar for that purpose. It defeats the purpose, however, if it is light years away and unreachable... which is why if it was far from the other planets (say, as far as Sedna is) but not impossibly far, than it could work well with the series. I imagine, scientific wise, all the planets would be rapidly thrown out of their stable orbits.

[YNM]

I suppose that if one cuts the planetary system out at Jupiter distance, then having this exotic object at hundreds of AU away from the central star would still be plausible.

Also, don't forget pulsars can have planet-sized bodies orbiting them - in fact, the first exoplanet to be discovered was actually around one such thing.

Edited January 16, 2017 by YNM

[ThiccRocketScientist]

3 minutes ago, YNM said:

I suppose that if one cuts the planetary system out at Jupiter distance, then having this exotic object at hundreds of AU away from the central star would still be plausible.

Also, don't forget pulsars can have planet-sized bodies orbiting them - in fact, the first exoplanet to be discovered was actually around one such thing.

If it is plausible, I love it! I want to have parts of my series which cannot be produced in Kerbal (requiring something like Universe Sandbox for cinematic shots of say, a pulsar, which I might be able to add into the kerbal video) but I also want it to be realistic. So a mini-system around a pulsar far out from Kerbol... pretty great if I say so myself. Thank you for your explanations.

 

[Hannu2]

There are stable solar systems around distant binary stars. If pulsar is very far away it would not disturb orbits of planets significantly. For example a pulsar with couple of Kerbol masses and distance of several tens times distance of Jool would fit to physics and story of the KSP, in my opinion. Size could be some tens of kilometers. Such a gravity field would probably break the physics of the game, but it could be avoided if all incoming probes would explode at much larger distance. It would be very realistic because any real material could not stand tidal forces and radiation near the neutron star.

However, real pulsars emits insane intensity of dangerous gamma radiation. You have to use very heavy artistic freedom to explain why such an object do not kill every lifeform in the solar system (except maybe some microbes very deep under ground).

[p1t1o]

30 minutes ago, Hannu2 said:

There are stable solar systems around distant binary stars. If pulsar is very far away it would not disturb orbits of planets significantly. For example a pulsar with couple of Kerbol masses and distance of several tens times distance of Jool would fit to physics and story of the KSP, in my opinion. Size could be some tens of kilometers. Such a gravity field would probably break the physics of the game, but it could be avoided if all incoming probes would explode at much larger distance. It would be very realistic because any real material could not stand tidal forces and radiation near the neutron star.

However, real pulsars emits insane intensity of dangerous gamma radiation. You have to use very heavy artistic freedom to explain why such an object do not kill every lifeform in the solar system (except maybe some microbes very deep under ground).

The deadly gamma radiation - is that part of the beam or is it radiated away in all directions?

[Hannu2]

I do not know exact radiation distribution around pulsar. Most of the energy is concentrated to narrow beams, but I suspect that there must be significant radiation levels all around neutron star. I would not like to go to measure in neutron star's solar system with handheld geiger counter.

[ThiccRocketScientist]

6 hours ago, Hannu2 said:

There are stable solar systems around distant binary stars. If pulsar is very far away it would not disturb orbits of planets significantly. For example a pulsar with couple of Kerbol masses and distance of several tens times distance of Jool would fit to physics and story of the KSP, in my opinion. Size could be some tens of kilometers. Such a gravity field would probably break the physics of the game, but it could be avoided if all incoming probes would explode at much larger distance. It would be very realistic because any real material could not stand tidal forces and radiation near the neutron star.

However, real pulsars emits insane intensity of dangerous gamma radiation. You have to use very heavy artistic freedom to explain why such an object do not kill every lifeform in the solar system (except maybe some microbes very deep under ground).

But how about a black hole as part of a trinary system, whereas the pulsar orbits the black hole, or the black hole orbits the pulsar, and it absorbs the radiation from one end whilst the other end is pointed towards interstellar space?

[Steel]

21 minutes ago, ThiccRocketScientist said:

But how about a black hole as part of a trinary system, whereas the pulsar orbits the black hole, or the black hole orbits the pulsar, and it absorbs the radiation from one end whilst the other end is pointed towards interstellar space?

Trinary systems are only stable in a narrow selections of cases and I'm not sure this is one of them. Also for your black hole and pulsar combined not to have any destabilising effects on the rest of the system they'd have to be pretty tiny. Also pulsars are characterised by their incredibly fast rotation, so unless your black hole is somehow orbiting it at a fair fraction of the speed of light and in perfect syncronicity with the rotation of the pulsar, then your situation won't work.

[ThiccRocketScientist]

Just now, Steel said:

Trinary systems are only stable in a narrow selections of cases and I'm not sure this is one of them. Also for your black hole and pulsar combined not to have any destabilising effects on the rest of the system they'd have to be pretty tiny. Also pulsars are characterised by their incredibly fast rotation, so unless your black hole is somehow orbiting it at a fair fraction of the speed of light and in perfect syncronicity with the rotation of the pulsar, then your situation won't work.

Yes, but if the majority of the radiation is emitting from the poles- where it is pointed in one direction (whereas the equator is constantly spinning and the heading is changing)

 

Anyway, do Kerbals die of radiation anyway?

[Steel]

2 minutes ago, ThiccRocketScientist said:

Yes, but if the majority of the radiation is emitting from the poles- where it is pointed in one direction (whereas the equator is constantly spinning and the heading is changing)

Annoyingly, the magnetic axis along which the beam is emitted and the rotational axis are not often aligned, hence why we see pulsars pulse, as opposed to just blasting us constantly which high energy radiation.

Edited January 17, 2017 by Steel

[Hannu2]

14 hours ago, ThiccRocketScientist said:

But how about a black hole as part of a trinary system, whereas the pulsar orbits the black hole, or the black hole orbits the pulsar, and it absorbs the radiation from one end whilst the other end is pointed towards interstellar space?

In my opinion that would be too artificial explanation. I would prefer for example that high energy physics in that world do not produce too much radiation around beams. There is no reason to copy real natural laws too strictly to story of cartoonish aliens in strangely scaled solar system.

[radonek]

I dont like to spoil your fun, but this is not very plausible. Pulsars are tiny, just a few kilometers, so all you could see from afar is a bright dot. If you get closer  then that, they will kill you. I'ts not just radiation, they possess impressive tidal forces and magnetic field that can rip atoms apart.

[kerbiloid]

Sp, probably the way to make it plausible would be a binary system of a regular star and the pulsar, with a hot gas plume from one to another (like a giant comet tail).
Maybe could be done with Kopernicus particles, I don't know.

On 17.01.2017 at 9:10 PM, ThiccRocketScientist said:

Anyway, do Kerbals die of radiation anyway?

They didn't, but Kerbalism mod makes them.

On 17.01.2017 at 8:42 PM, ThiccRocketScientist said:

a black hole as part of a trinary system, whereas the pulsar orbits the black hole, or the black hole orbits the pulsar

There will be two bright points instead of one.

[p1t1o]

25 minutes ago, kerbiloid said:

Quote

a black hole as part of a trinary system, whereas the pulsar orbits the black hole, or the black hole orbits the pulsar

There will be two bright points instead of one.

Along with some weird gravitational lensing effects, presumably.

[VikingStormtrooper]

I read somewhere that, if a typical magnetar (magnetic pulsar, a kind of pulsar with a tremendous magnetic field) could replace the Sun, our credit cards would be demagnetized. Even at 1 AU!

[Hannu2]

11 hours ago, radonek said:

I dont like to spoil your fun, but this is not very plausible. Pulsars are tiny, just a few kilometers, so all you could see from afar is a bright dot. If you get closer  then that, they will kill you. I'ts not just radiation, they possess impressive tidal forces and magnetic field that can rip atoms apart.

Pulsars are not visually intersting, ecpecially because KSP can not draw relativistic effects. But it could be used to give player an interesting possibility to play with extreme dv.

[magnemoe]

3 hours ago, Hannu2 said:

Pulsars are not visually intersting, ecpecially because KSP can not draw relativistic effects. But it could be used to give player an interesting possibility to play with extreme dv.

Yes, however its an high chance that an close flyby would mess up the physic a lot. 

Once had an part clip trough the surface on Mun, it fell towards the singularity at the center, as gravity increases as you get closer acceleration also increased. 
Because KSP only calculate physic around 20 times each second you get an weird effect, acceleration increases toward infinite as you get closer and your calculated speed will be stupid high. 
So high that next time after passing the singularity you will already be pretty far away and the next calculated negative acceleration will be far lower than the positive so you end up with an huge speed gain. 
Effect will be less extreme with an neutron star as its not an singularity but you are still likely to get huge errors, you would not get an stable orbit. 

[p1t1o]

31 minutes ago, magnemoe said:

Yes, however its an high chance that an close flyby would mess up the physic a lot. 

Once had an part clip trough the surface on Mun, it fell towards the singularity at the center, as gravity increases as you get closer acceleration also increased. 
Because KSP only calculate physic around 20 times each second you get an weird effect, acceleration increases toward infinite as you get closer and your calculated speed will be stupid high. 
So high that next time after passing the singularity you will already be pretty far away and the next calculated negative acceleration will be far lower than the positive so you end up with an huge speed gain. 
Effect will be less extreme with an neutron star as its not an singularity but you are still likely to get huge errors, you would not get an stable orbit. 

What about a sort of "kerbal" neutron star.

We have "kerbal" planetary masses - in that due to their truncated size but "normal" gravity and atmospherics, they appear to be made of an incredibly dense material. Not physically accurate, but it facilitates gameplay.

A "kerbal" neutron star might be be minmus-sized, but with say 50G surface gravity. Might be best not to *call* it a neutron star, perhaps something like "Kerbol System Dense Mass Anomaly".

That way you get the opportunity to explore manouvers in a high-gravity environment, avoid software glitching and have a good reason to sidestep any weird relativity effects.

[magnemoe]

5 minutes ago, p1t1o said:

What about a sort of "kerbal" neutron star.

We have "kerbal" planetary masses - in that due to their truncated size but "normal" gravity and atmospherics, they appear to be made of an incredibly dense material. Not physically accurate, but it facilitates gameplay.

A "kerbal" neutron star might be be minmus-sized, but with say 50G surface gravity. Might be best not to *call* it a neutron star, perhaps something like "Kerbol System Dense Mass Anomaly".

That way you get the opportunity to explore manouvers in a high-gravity environment, avoid software glitching and have a good reason to sidestep any weird relativity effects.

Yes, I would go down in size and up in gravity, make it 10 km like an neutron star, then see how high gravity you can get away with 1000 g should probably work. 
Giving it an small moon would also be fun, it would be an real target to land on. Perhaps two, one at some decent distance and one close in. 

[p1t1o]

30 minutes ago, magnemoe said:

Yes, I would go down in size and up in gravity, make it 10 km like an neutron star, then see how high gravity you can get away with 1000 g should probably work. 
Giving it an small moon would also be fun, it would be an real target to land on. Perhaps two, one at some decent distance and one close in. 

Whatever combination works best with KSP physics.

It could even have full-blown planets orbiting it, SOIs would be much smaller, yes I can see it being an interesting environment to add to KSP.

Question: what is the luminosity of a neutron star like? Would it shine like a sun or be more a dull glow? Or even dark?

[PB666]

PUlsar binary systems would not be a happy place for kerbal-kind.

1. Even low magnetic pulsars would play great havoc on any ionosphere. Potentially ripping the atmosphere off the planets rapidly.

2. Yes relativistic effects occur for any two bodies that whose inertial reference frames are not strait lines from the other objects pov. Significant relativistic effects, because of the rate of rotation you would notice pulses in space-time at relatively close distance, this could cause shuttering of buildings or rattling of windows.

https://en.wikipedia.org/wiki/Pulsar#Gravitational_waves_detectors

https://en.wikipedia.org/wiki/Pulsar#Milestones

Imagine trying to build a brick wall as the brick and mortar are shuttering while you lay the brick, or to have a cake rise in the oven.

3. I rather does not matter the radiation, being blasted by high amounts of any kind of radiation which does not persist (for example a planet that passes in front ot the beam of a pulsar for 5 days in its year) could have devastating effects on the life on that planet. There is no orbit a planet can have except one that is coplanar with that of the pulsar that stops this from happening.

 

[radonek]

This brings up a question: could KSP physics be modded to simulate proper tidal forces? I guess it would be, umm, educative, to let people try flyby of some dense object and see their ship torn to pieces. (and, undoubtely, to reach limits of strutting hell :-)

[kerbiloid]

7 hours ago, radonek said:

This brings up a question: could KSP physics be modded to simulate proper tidal forces? I guess it would be, umm, educative, to let people try flyby of some dense object and see their ship torn to pieces. (and, undoubtely, to reach limits of strutting hell :-)

This happens from time to time even without tidal forces.