New comparison addon (work in progress)

[t00fri]

Can someone suggest a *well known* star which is *much* smaller than our Sun, excluding Proxima Cen ?

Here is the smallest star EVER: OGLE-TR-122b



Here are the sources for the ESO-image. It's found in many WEB sites.
http://www.newscientist.com/article.ns?id=dn7098


Bye Fridger

[Cham]

Thanks Fridger. If there's enough accurate info on it, I'll add it to my comparison addon. This star isn't in Celestia's database.

If only Chris could raise the number of stars with planets in Celestia. I raised it myself to 20 in the render.h code, using the info above, but it's not in the official version.

[Cham]

Here's a paper describing that tiny star :

http://arxiv.org/pdf/astro-ph/0501611

However, I'm yet unable to find its AbsMag and there isn't much precision about its spectral class (class M).

[bdm]

And what about Gliese 845 Ba ?

In Celestia's database, it's a T1V brown dwarf and has almost exactly the same radius as Alula Australis Bb. And it's nicely described there :

http://www.solstation.com/stars/eps-indi.htm

Epsilon Indi Ba/Bb are a binary brown dwarf. They are notable for being the closest known brown dwarfs to the Sun and for being a binary. It might be useful to include both of them.

PS: I like this addon, good work

[fsgregs]

Cham:

Your individual star textures are very nice. Will they all be present in the add-on when it is released?

Frank

[Cham]

The textures I'm using are all variations of standard textures found everywhere for Celestia (from Don or Rassilon ?). I've edited them to remove any pattern repetition among the stars, since they are standing side by side.

Yes, they will be included in the final addon.

I'm just waiting from Chris to correct the current limitation to 16 stars with planets, since I'm using 18 stars.

[hank]

I'm just waiting from Chris to correct the current limitation to 16 stars with planets, since I'm using 18 stars.

Cham,

What do you see as the advantage of this approach over displaying the objects in multiple views?

- Hank

[Cham]

I'm just waiting from Chris to correct the current limitation to 16 stars with planets, since I'm using 18 stars.

Cham,

What do you see as the advantage of this approach over displaying the objects in multiple views?

- Hank

Well, you can see more at the same time, and the feel is very different. More "user friendly" in some way, especially when you look at Earth, Jupiter, and few stars around all at the same time, while rotating around them. And there are some nice floating labels for each star in the comparison.

Also, Celestia is very innacurate with cool stars. The radius is badly wrong for most red dwarfs and giants.

[s3nn0c]

Another very good idea, looks really great. But you can use it to show more than just sizes! This is a very good moment to show shapes of stars and their changes too. Giants in general are not perfectly spherical - it's impossible on this scale! Maybe you should try to make a giant as a combination of a few spheres which rotate around its "centre of mass"? Here is a numerical simulation of Betelgeuse's shape:

http://www.aip.de/~mst/pub_files/images ... 0086_E.gif
http://www.aip.de/~mst/pub_files/images ... _I1brm.jpg

There are movies somewhere too, I dont have a link to them - if you want I can send them to you (timescale of changes and their sizes are important).

I think it would be a good idea to add Altair or Achernar due to their elongated shape.

http://www.jb.man.ac.uk/news/starshape/im2.gif

AFAIK Deneb rotates very fast, it should be elongated too.

I mean you shouldnt put all these stars in your extension, but it would be really useful to see stars which differ in sizes AND shapes.

And something about VV Cephei:

"The three stars with the largest known sizes are KW Sagitarii (distance 9,800 light-years), V354 Cephei (distance 9,000 light-years), and KY Cygni (distance 5,200 light-years), all with radii about 1500 times that of the Sun, or about 7 astronomical units(AU). For comparison, the red super-giant star Betelgeuse is known from other work to have a radius about 650 times that of the Sun, or about 3 AU. If one of these stars were placed in the sun?€™s location, its outer layers would extend to midway between the orbits of Jupiter (5.2 AU) and Saturn (9.5 AU). The previous record holder, mu Cephei comes in a close fourth in size in the study. The only other star for which a very large size has been claimed is the binary star system VV Cephei, which consists of a red super-giant and a hot companion orbiting within a common gaseous envelope, in which the gravitational forces of the companion have distended the surface of the super-giant and the meaning of the size of the star is therefore fuzzy. None of the stars in the new study are believed to be binaries, and thus their properties tell us about the extreme sizes that normal stars reach."

http://www.noao.edu/dir/proj-rep/proj-rep-05.pdf

Please also check this link (look carefully at Vega and Tsih!):

http://pl.youtube.com/watch?v=iwCpcoS0jKc

[Cham]

Yes, I also tried to give the stars a shape other than spherical, using some meshes. However, I ran over a problem with Celestia : there's a huge depth sorting bug with their glare, if the shape isn't spherical. Very sadly, I had to abandon this idea.

Currently, Celestia is extremely weak, when it comes to addons creation. Its limitations are very strong. I'm even thinking about stopping definitively any addon creation, because of all these bugs and weaknesses. The only things we can do safely, without running into some kind of problems, are textures on simple spherical objects ("balls painting") and spacecraft/asteroid models.

[fsgregs]

Searching the web found reference to a star named VY Canis Majoris, which apparently may be up to 2100 solar radii in size, making it the biggest star in size. Apparently, it is ejecting mass in its final death throes so that there is not a clear edge/photosphere, making its size hard to narrow down.

Anyone else have any thoughts on it?

Frank

[reptile]

guys is this working becouse my celestia crash when i go to Stars_comparison is some way to fix this? great idea to make addon like this.

[chris]

guys is this working becouse my celestia crash when i go to Stars_comparison is some way to fix this? great idea to make addon like this.

Which version of Celestia are you using?

--Chris

[reptile]

ver 1.5.1
say's this...Error signature- AppName: celestia.exe
AppVer: 1.5.1.0
ModName: celestia exe
Offset: 001e39c6
????

[reptile]

ok so nobody know what is it and whay celestia crash.
Is this in progres or is finish ,....i hope this is not finish becoase mybe that is reason whay celestia crash.

[dovlex]

im looking for this addon long time and my celestia crash to...what is the problem??

[Cham]

The addon is finished since a pretty long time now. However, I never published it yet since it's using some features from Celestia 1.6.0. I was planning a release (with many many other addons) after 1.6.0 is officially out. Sorry for the wait time. The addons I'm doing are done with Celestia 1.6.0 in mind (most of them are now "Celestia layers").

The crash you're experiencing may be related to an "old" bug which was corrected by Chris, last year (I don't remember when), and which was related to the maximum number of stars that can be rendered in the same system. With 1.6.0, there isn't any limit to this number (well, maybe it's actually several thousands, I can't say )

[dovlex]

Thank cham, maybe Chris will share his version of this addon with as, or explain how to make this addon work?

[Joey P.]

[removed]

[Joey P.]

[removed]