Populating WLM (and other galaxies) with REAL stars

[LukeCEL]

Hey everyone. I revisited the globular clusters add-on, and was able to extract a lot more globular clusters. The new version contains 181 globular clusters! Any problem that affects the old version also affects the new version, by the way.

[Art Blos]

LukeCEL < Why the new version does not contain clusters from the previous one? I found only three repetitions.

Added after 2 hours 15 minutes:
And yet, why did you originally publish 52 clusters, and a day later left only 24?

[LukeCEL]

And yet, why did you originally publish 52 clusters, and a day later left only 24?

The first time I made a mistake with the data, so I had to re-do the file, and had to remove some globular clusters because they had incorrect numbers. (The second version isn't perfect either, but it's definitely better than the first one.)

Why the new version does not contain clusters from the previous one? I found only three repetitions.

It must be a problem with the cluster names themselves. Globular clusters, like BA 3-9 have several designations: "BA 3-9", "Bol 400", "SKHB 343", etc. So when searching through the data, it might have missed the globular cluster because it was listed under a different name. So I'll look into that.

[LukeCEL]

Okay, I think I fixed the problem with the globular cluster designations. This is the newest version, and contains 213 globular clusters.

[Art Blos]

Okay, I think I fixed the problem with the globular cluster designations. This is the newest version, and contains 213 globular clusters.

Perfectly! Thank you!

[Anthony_B_Russo10]

It's nice to have real stars in those galaxies, especially Sculptor dSph, considering the stars I have that galaxy are fictional.

[LukeCEL]

Here's about 2000 stars in the Andromeda Galaxy (M 31). The stars are definitely arranged into a spiral, but the Andromeda Galaxy is so large and the stars so far apart from each other that's its hard to see it by and large. I've done a final check, but there might still be mistakes.

Enjoy:

[Art Blos]

Here's about 2000 stars in the Andromeda Galaxy (M 31). The stars are definitely arranged into a spiral, but the Andromeda Galaxy is so large and the stars so far apart from each other that's its hard to see it by and large. I've done a final check, but there might still be mistakes.

I hope that in future the number of stars increases. In such a huge galaxy, it can not be otherwise.

[Gurren Lagann]

Here's about 2000 stars in the Andromeda Galaxy (M 31). The stars are definitely arranged into a spiral, but the Andromeda Galaxy is so large and the stars so far apart from each other that's its hard to see it by and large. I've done a final check, but there might still be mistakes.

Where is the other 9058 entries from Simbad?

[LukeCEL]

Where is the other 9058 entries from Simbad?

They're not included for several reasons:

1. SIMBAD includes a membership probability—the odds that a particular object is a member of that parent, in this case M 31. I only include the object when the probability is at least 90%.
2. Some of the objects aren't stars. If they're globular clusters, I might be able to add them back, but for things like molecular clouds or open clusters, I can't really add them.
3. For M 31, many of the stars come from this paper: Sarajedini et al. (2009). The stars from that paper all fit in two compact squares (click on this for a view in the Aladin widget). If I included them, the stars wouldn't be evenly distributed, so I just removed them all.

[Art Blos]

but for things like molecular clouds or open clusters, I can't really add them.

What is the problem of adding open clusters? They are implemented very simply, they do not need to have real stars.

[LukeCEL]

What is the problem of adding open clusters? They are implemented very simply, they do not need to have real stars.

True, they don't really need to have real stars. However, I prefer them to be that way. My LMC and SMC addon has real open clusters, that I've built by taking "nearby" stars and clustering them together.

[SpaceFanatic64]

Luke, do you think you could try populating Sagittarius dSph with stars again?

[LukeCEL]

Luke, do you think you could try populating Sagittarius dSph with stars again?

I tried to do this once, but I forgot why I couldn't. I posted this on the forum, which roughly explains why.

You should know that the Sagittarius dSph is really tenuously defined: not a concrete dwarf galaxy like it appears in Celestia, but more like a bunch of globular clusters and a stream of stars. In theory, you could populate the galaxy with stars, and it would look normal. It's just that SIMBAD pulls information from scientific papers, like Frinchaboy et al. (2012). The authors of those scientific papers have only observed a sample of stars in select fields, which are designated as "Major+00", "SE+04", etc. Some of them are very far from where Celestia defines Sagittarius dSph to be, which is why the image that I posted looks kind of messy.

[SpaceFanatic64]

Oh. But couldn't you just modify the coordinates of the galaxy to fit with the stars?

[LukeCEL]

Oh. But couldn't you just modify the coordinates of the galaxy to fit with the stars?

Well, I only modify the "Distance" parameter. For most extragalactic stars, the actual distances within the galaxy aren't known. I generate random numbers—they're total guesses, and unlikely to be correct. However, I don't do this with the coordinates (right ascension and declination) because those are available, and if I modified those coordinates, they'd for sure be incorrect. Actually, this generally applies to most things I create—I use real data if I can find them, and generate random (but plausible) data if I can't.

[SpaceFanatic64]

Oh, I see. And now, could you try creating an STC code for MACS J1149 Lensed Star 1, the farthest star known?

[LukeCEL]

And now, could you try creating an STC code for MACS J1149 Lensed Star 1, the farthest star known?

Okay, I quickly put together some code using data from the Wikipedia article about it:

Code: Select all

"MACS J1149 Lensed Star 1"
{
   RA 177.3982917
   Dec 22.3965
   AppMag 29.9 # typical magnitude: was temporarily 28.4 during lensing event
   SpectralType "B"
   Distance 1.44e+10 # comoving distance
}

However, the star won't display because Celestia doesn't show stars that are over 10 million light years away. (See this thread for details.)

[SpaceFanatic64]

Also, Luke, could you try creating an updated version of the largest stars? There are many more stars listed on Wikipedia now, and it would be great if you could integrate them into Celestia.

[LukeCEL]

Also, Luke, could you try creating an updated version of the largest stars? There are many more stars listed on Wikipedia now, and it would be great if you could integrate them into Celestia.

Yeah, unfortunately I don't really trust the Wikipedia page anymore. It went through some serious edit wars, and now the article is marked as possibly having some "inappropriate or misinterpreted citations that do not verify the text".