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Dr. Kaii
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Intergalactic stars!

01 Apr 2017 16:04

I'm sure this has been pointed out over and over, but we really would like to see procedurally generated intergalactic stars! Did you know that 10% of all stars in the Virgo Cluster are inter-cluster? It includes planetary nebulae, star forming regions, globular clusters etc. 
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Gnargenox
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Intergalactic stars!

01 Apr 2017 18:23

Might as well add Dark Matter then too :) We have recently seen Rouge Black Holes as well. They would need to have a velocity added to them, since that is a requirement to actually leave the Galaxy.
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Watsisname
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Intergalactic stars!

01 Apr 2017 19:32

Well, intergalactic stars would be places you could actually visit and see, and many would even have planets around them.  So there's a compelling case for showing them.  Dark matter on the other hand is just just an invisible fog of particles around galaxies.  If dark matter is added then I think it should be along with other non-visible things like magnetic field.

One question with showing intergalactic stars may be in how/where to generate them.  The more simple population would be the hypervelocity stars, which were members of binary systems that got ejected by passing too close to the central black hole.  So they should have some spherical distribution about the galaxy, almost like a very diffuse globular cluster.  They would have fast velocities almost directly radially outward, but their motions would be unnoticeable except on very long timescales -- the same kind of timescale for which galactic rotation would be apparent.  Such stellar motions likely will not be shown any time soon.

The other population are from tidal streams thrown off during galactic mergers, so they have more complex distributions which would require a new generation system.  If SE simulated galactic mergers then they would be a natural occurrence, but that's also something not likely to be shown any time soon.
 
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FastFourierTransform
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Intergalactic stars!

02 Apr 2017 11:31

Dr. Kaii wrote:
Source of the post I'm sure this has been pointed out over and over

In fact it was but I agree we need a gentle reminder :D

Just to point something out. Not only should be procedurally generated but also generated considering there are integalactic stars in catalogue right now. For example HE 0437-5439 it's 200.000 ly from us (consider that the diameter of the Milky Way is around 120.000 ly), os consider ULAS J074417.48+253233.0 or ULAS J001535.72+015549.6, that are respectively 770.000 ly and 890.000 ly away. ULAS J001535.72+015549.6 is in fact more than 7 milky way diameters away (I attached a picture from that distance and angle of the Milky Way using SE in the old forum but I can't find it again).


Another important thing is that these stars have motions that trace back to our galaxy, so they are all runaway stars that escaped the Milky Way. This imposes several conditions on the future representation on Space Engine. First of all, the farthest from a galaxy the older the star has to be. In fact it should be impossible to find O type stars too far from the galaxy in intergalactic space for example, since they live at max 6 million years (they become B type or die in a supernova explosion before that). There are hipervelocity stars with 1200 km/s speeds exiting the Milky Way (none are so massive as main sequence O type stars but we are going to make the calculations with that), like US 708 that is 62.000 ly away from Earth. Considering all of this the maximum distance we should expect an O type star in intergalactic space is 24.000 ly from the galactic plane (inside the Milky Way). The same calculation can be made for B type stars; considering they should not live more than 90 million years, we shouldn't find any of those more than 360.000 ly from the galactic plane. So there is a gradient in the stellar type for intergalactic stars related to the distance to the closest galaxy that has to be taken into account for the sake of realism.

This is avoinding the idea of stellar formation in intergalactic space, that maybe could show up once in a while. I don't know the probability but it would be awesome to search for blue stars in the middle of giant intergalactic voids, finding one would be awesome, it would mean that a giant gas cloud in the middle of nowhere collapsed because of the existence of an unknown perturbation. But the probability of finding one in the game should be tiny, really tiny.

For M type stars and stars with lifespans of 100 billion years there is not such a big void as to be perfectly clean of runaway M-stars from neighbouring galaxies, so all the intergalactic space should have some M stars from time to time. The only void that could maybe have a central zone depleted from any stars could be the Canes Venatici Supervoid. For M stars to be absent you have to go 400.000.000 ly away from the galaxy, and this void is 1.300.000.000 of ly across, so maybe at the center you could have distances grater than 400.000.000 ly from the closest galaxy. But it would be a very strange ocurrence in all the SE universe.
 
A-L-E-X
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Intergalactic stars!

04 Apr 2017 20:49

Watsisname wrote:
Well, intergalactic stars would be places you could actually visit and see, and many would even have planets around them.  So there's a compelling case for showing them.  Dark matter on the other hand is just just an invisible fog of particles around galaxies.  If dark matter is added then I think it should be along with other non-visible things like magnetic field.

One question with showing intergalactic stars may be in how/where to generate them.  The more simple population would be the hypervelocity stars, which were members of binary systems that got ejected by passing too close to the central black hole.  So they should have some spherical distribution about the galaxy, almost like a very diffuse globular cluster.  They would have fast velocities almost directly radially outward, but their motions would be unnoticeable except on very long timescales -- the same kind of timescale for which galactic rotation would be apparent.  Such stellar motions likely will not be shown any time soon.

The other population are from tidal streams thrown off during galactic mergers, so they have more complex distributions which would require a new generation system.  If SE simulated galactic mergers then they would be a natural occurrence, but that's also something not likely to be shown any time soon.

supermassive black hole mergers creating new universes :)
 
A-L-E-X
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Intergalactic stars!

04 Apr 2017 20:51

FastFourierTransform wrote:
Dr. Kaii wrote:
Source of the post I'm sure this has been pointed out over and over

In fact it was but I agree we need a gentle reminder :D

Just to point something out. Not only should be procedurally generated but also generated considering there are integalactic stars in catalogue right now. For example HE 0437-5439 it's 200.000 ly from us (consider that the diameter of the Milky Way is around 120.000 ly), os consider ULAS J074417.48+253233.0 or ULAS J001535.72+015549.6, that are respectively 770.000 ly and 890.000 ly away. ULAS J001535.72+015549.6 is in fact more than 7 milky way diameters away (I attached a picture from that distance and angle of the Milky Way using SE in the old forum but I can't find it again).


Another important thing is that these stars have motions that trace back to our galaxy, so they are all runaway stars that escaped the Milky Way. This imposes several conditions on the future representation on Space Engine. First of all, the farthest from a galaxy the older the star has to be. In fact it should be impossible to find O type stars too far from the galaxy in intergalactic space for example, since they live at max 6 million years (they become B type or die in a supernova explosion before that). There are hipervelocity stars with 1200 km/s speeds exiting the Milky Way (none are so massive as main sequence O type stars but we are going to make the calculations with that), like US 708 that is 62.000 ly away from Earth. Considering all of this the maximum distance we should expect an O type star in intergalactic space is 24.000 ly from the galactic plane (inside the Milky Way). The same calculation can be made for B type stars; considering they should not live more than 90 million years, we shouldn't find any of those more than 360.000 ly from the galactic plane. So there is a gradient in the stellar type for intergalactic stars related to the distance to the closest galaxy that has to be taken into account for the sake of realism.

This is avoinding the idea of stellar formation in intergalactic space, that maybe could show up once in a while. I don't know the probability but it would be awesome to search for blue stars in the middle of giant intergalactic voids, finding one would be awesome, it would mean that a giant gas cloud in the middle of nowhere collapsed because of the existence of an unknown perturbation. But the probability of finding one in the game should be tiny, really tiny.

For M type stars and stars with lifespans of 100 billion years there is not such a big void as to be perfectly clean of runaway M-stars from neighbouring galaxies, so all the intergalactic space should have some M stars from time to time. The only void that could maybe have a central zone depleted from any stars could be the Canes Venatici Supervoid. For M stars to be absent you have to go 400.000.000 ly away from the galaxy, and this void is 1.300.000.000 of ly across, so maybe at the center you could have distances grater than 400.000.000 ly from the closest galaxy. But it would be a very strange ocurrence in all the SE universe.

Does the program properly model actual superclusters and supervoids as well as large scale features like The Great Attractor?  Is there any way for us to go far back or forwards in time and see how these large scale structures looked in the past or will look in the future?
 
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Watsisname
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Intergalactic stars!

04 Apr 2017 21:34

A-L-E-X wrote:
Source of the post supermassive black hole mergers creating new universes

?
 
A-L-E-X
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Intergalactic stars!

04 Apr 2017 23:23

Watsisname wrote:
A-L-E-X wrote:
Source of the post supermassive black hole mergers creating new universes

?

I remember reading about a supercomputer simulation a few years ago that modeled these behemoth mergers and said it was a possibility.  There was a connection to something called a Hopf Fibration- which is a structure which pops up in physics in interesting places.  It's toroidal.
 
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Watsisname
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Intergalactic stars!

05 Apr 2017 00:17

Mainly I didn't understand the relevance to the subject of intergalactic stars, but that's very interesting!

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