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Forum » SpaceEngine » Space Journeys » Milky Way Arms
Milky Way Arms
EdBearDate: Sunday, 04.09.2011, 07:39 | Message # 1
Observer
Group: Users
Canada
Messages: 10
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I love this program a lot. Really a lot.

I'm trying to understand how the spiral arms of the Milky Way have been designed though - was there a particular model/diagram that was used to determine the place of Sol and the relative positions of the spiral arms?

The reason that I ask is because I've been using this to help me understand the relationship between the Milky Way in the night sky and the actual features of the galaxy, but I've been confused a few times when comparing the Milky Way in SpaceEngine to other pictures and diagrams.

For instance in Cygnus (in the program), if you travel up to galactic north you end up seeing that Deneb is essentially in the Perseus Arm, while most of the references I've seen have the Cygnus part of the Milky Way as looking along much of the local spur and into the Sagittarius Arm. Is there a different model that was used for putting this together, or does the program use a more approximate way of doing the galactic structure?

I'm not complaining either way - I love the program to pieces - but I just want to understand how far I can use it for this sort of thing. Thanks!
 
SpaceEngineerDate: Sunday, 04.09.2011, 16:21 | Message # 2
Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4796
Status: Offline
SpaceEngine has limited model details of the Milky Way. You can't see all the dark clouds that is seen on Milky Way photos. Astronomers don't really know the real 3D structure of our galaxy, only some of it's components (like hydrogen clouds). I use the famous Spitzer model of Milky Way, it can be found on the Internet.

I place Milky Way model at its known place (the galaxy center is 8 kpc from Sun in the Sagittarius constellation) and rotate it according to the data of orientation of galactic plane and bar. The sprite model itself consists of 10-20 thousand sprites, randomly generated using Spitzer's texture as the template. Dust sprites are placed randomly too, so it doesn't match real dust clouds distributions (which are also unknown). So according to Spitzer's model, our neighborhoods must be correct. Deneb may be much more closer to the Sun than in HIPPARCOS catalog as used by SpaceEngine (and its much more dimmer, near 6000 suns, but in HIPPARCOS it is 250000 suns due to the big distance).

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EdBearDate: Sunday, 04.09.2011, 18:04 | Message # 3
Observer
Group: Users
Canada
Messages: 10
Status: Offline
Excellent, thanks - knowing it's the Spitzer model helps me a great deal!

My notion about being able to place actual galactic structure against the night sky for real is probably a hopeless one anyway, apart from some very general directions (this arm sort of here, that arm over there, etc).
 
JHillDate: Sunday, 04.09.2011, 20:51 | Message # 4
Observer
Group: Users
United States
Messages: 19
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SpaceEngineer, what databases do you use for the star info?




Sed nos soli stantes. Solus stamus unita.
In multis unum surgimus. Sub una resurgemus totidem.
 
SpaceEngineerDate: Monday, 05.09.2011, 14:50 | Message # 5
Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4796
Status: Offline
EdBear, if someday I make the 3D editor for the galaxy, it will be possible to place dust and light sprites manually to match the real Milky Way photo.

JHill, I use the HIPPARCOS star catalog.

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