Populating WLM (and other galaxies) with REAL stars

[LukeCEL]

After a long hiatus, I have finished another add-on.

Here's about 3900 stars in the Triangulum Galaxy (M 33). Compared to the Andromeda Galaxy, I could use more stars; combined with the fact that the Triangulum Galaxy is smaller means that the coverage just looks a lot nicer.

A famous star, Romano's Star, disappeared when I was working through the spreadsheet. I have no idea why. I allow stars if SIMBAD says the probability of membership is at least 90%, and Romano's Star definitely makes the cut. If anyone wants the star I'll write some specific code for it.

Enjoy:

[SevenSpheres]

Nice! Though, could you possibly redo the LMC? Currently it's missing several well-known stars, such as R136a1. FWIW, here is a recent paper on some binary stars in the LMC.

[LukeCEL]

could you possibly redo the LMC? Currently it's missing several well-known stars, such as R136a1.

I don't know if I can do that much about the LMC missing stars like R136a1. Even though R136a1 is clearly part of the LMC, SIMBAD doesn't say anything about it's membership. I don't know why.

I could just add them in by hand, but that would be annoying and then there'd be no end to what I could potentially put in these files.

FWIW, here is a recent paper on some binary stars in the LMC.

Looks interesting, thanks. I don't think any of those stars are in my LMC file, due to the reasons stated above, but I'll see.

[LukeCEL]

Hey everyone, here's some more files.

The first file adds over 1200 stars in Leo I. The second file adds about 380 stars in Leo II.

I've also done Leo A, but the file only has about 50 stars, so it's hardly populated by any means. However, in the default version of Celestia, Leo A is rendered as a blob (Type "Irr") and not its more elongated shape. So, for the stars to actually fit in the galaxy, I did make an updated definition for Leo A:

Code: Select all

Galaxy "Leo A:DDO 69"
{
        Type  "E5"
        RA            9.9906
        Dec          30.7464
        Distance   2.251e+06 # method: rgb
        # Radius        1533
        Radius          3658
        AbsMag        -11.36
        Axis    [  0.8684  -0.3442   0.3569]
        Angle     164.758
        InfoURL  "http://simbad.u-strasbg.fr/sim-id.pl?Ident=Leo A"
}

Enjoy:

[Art Blos]

Yeah! Continue to populate the galaxies.

[LukeCEL]

This file adds 270 stars in the Phoenix Dwarf (and the nearby area, since it's quite widely distributed).

Enjoy:

[Anthony_B_Russo10]

We always need more stars for Celestia.

[LukeCEL]

This add-on adds about 730 stars in Barnard's Galaxy (NGC 6822). Unfortunately out of the over 3000 children listed in SIMBAD, most of them had membership probabilities of 75%, which is less than the 90% threshold that I use. Nevertheless, Barnard's Galaxy has a fair amount of interesting stars, including supergiants, Cepheids, and a few planetary nebulae.

Enjoy:

[Art Blos]

We need more gold stars! MOAR!!!

[LukeCEL]

This add-on adds over 1400 stars around NGC 185. Unfortunately, SIMBAD's star distribution was ill-suited for this, since it looks like astronomers mostly surveyed the area around NGC 185. Oh well.

Enjoy:

[LukeCEL]

This add-on adds nearly 300 stars around Andromeda II (And II). SIMBAD's member stars are distributed mostly around the galaxy instead of in the galaxy itself, but this time it's much more even. I've estimated spectral types from V-I indices using Eric Mamajek's stellar parameters table.

Enjoy:

[LukeCEL]

Here's an update to the Triangulum stars add-on. This version has the same amount of stars, but it adds more realistic spectral types to some supergiant stars, estimated from temperatures and using Mamajek's aforementioned table. These temperatures come from Drout et al. (2012): The Yellow and Red Supergiants of M33. This helps make some radii estimates a little bit more realistic; previously there were some with upwards of 7,000 solar radii. I think in future files I'll just not include any late-type supergiants: no M9Ia's, for example.

Enjoy:

[LukeCEL]

A long while ago, I made a globular clusters add-on for Andromeda, but I could never figure out what the Radius parameter is. Finally though I know what it is: Chris Laurel (on the Discord server) said that it's the radius at which the surface brightness (μ) is 25 magnitudes/(arcsec^2). That's what it means by "mu25 isophote".

In Fridger's globulars.pl, which was used to create the original globulars.dsc, there's a formula for getting the mu25 isophote value using c, the King concentration value, and mu_V, the central surface brightness (I think).

So that means my Andromeda globulars add-on is wrong... yet again. I may update the Andromeda globulars add-on again if I have time.

Luke

[selden]

Maybe just document what is wrong about them?

Sometimes "perfect" is an enemy of "good enough".

[LukeCEL]

Sometimes "perfect" is an enemy of "good enough".

True. I don't know how annoying the globular clusters would be to redo, but it will almost certainly be nontrivial to do. Another thing to consider is that I'm probably the only one that cares about globular clusters to this (somewhat insane) extent

In any case, a good priority would be to document the parameters in detail on the Wikibook so people know what all the parameters mean.

[LukeCEL]

After doing some tests with the "Radius" parameter for globular clusters, it seems like it only affects the size of the globular's "bounding box"; i.e. where to put the red pointy markers. So that means that the actual placement of the sprites is still correct.

Anyway, it's come to my attention that some stars in the Triangulum stars add-on have invalid or incorrect spectral types, because they are luminous blue variables (LBVs). These have been fixed, and are now rendered as normal supergiants. Thank you SevenSpheres for notifying me of this problem!

Enjoy:

[LukeCEL]

After some renewed attention, it looks like the Triangulum stars add-on is in need of a few tweaks! Specifically:

1. The brightness of Mira-type stars is way over the place, causing some of them to be as small as ~20 solar radii. I've bumped up the brightness on those.

2. Other stars, namely red supergiants, have spectral types so late (e.g. M6I) that their radii are many thousands of radii. I've fixed this by using earlier spectral types. This is probably an issue with interstellar reddening for B- and V-band magnitudes.

3. A few objects, namely BCLMP 710 and a few others, seem to not be stars entirely. BCLMP 710 for example is a molecular cloud or something, from looking at the few papers and VizieR sources that covered it. In any case, not a carbon star.

Anyway, the fixed version is below. Thanks to those who brought this to my attention (Gurren Lagann and Trolligi112477-ww, I believe). Enjoy:

[LukeCEL]

This add-on adds about 860 stars in IC 10. It is the nearest starburst galaxy, so there are a lot of Wolf–Rayet stars in this one. There is also a high-mass X-ray binary (IC 10 X-1), with one of the highest-mass black holes known. You're welcome to add accretion disks or something, if you want.

The hierarchy of objects for stars within IC 10 is quite messed up, apparently due to one paper (Massey et al. (2017)), so I had to delete some stars to prevent duplicates.

Enjoy:

[LukeCEL]

I've gone around and fixed a few of my add-ons.

M 33 / Triangulum Galaxy: The problematic system here was M33SSS J013300.38+303416.8. It is listed as a Mira variable, but the V-magnitude from SIMBAD makes it unrealistically bright, and thus, large. I've changed the spectral type from "MIII" to "M0III", which reduces the radius from 3000 Rsol to a slightly more acceptable 1300 Rsol.

NGC 6822 / Barnard's Galaxy: for the nova AT 2017fvz, the binary stars were separated too far, at a distance which would make accretion (and thus a nova) unlikely. I've rewritten the definition so the two stars are now much closer to each other.

M 31 / Andromeda Galaxy: this one had the same issue as before, but for much more systems. The systems are still defined as an M0III + D system for increased visibility, but the primary and secondary stars are now closer to each other.

I have also finished another add-on: this one adds over 1000 stars in NGC 147, a dwarf elliptical/spheroidal galaxy. The stars are quite scattered, and often fall outside of the bounds of the galaxy as defined in Celestia.

Enjoy:

[LukeCEL]

This add-on adds over 190 stars to the Ursa Minor Dwarf Galaxy.

Despite having over a thousand listed children in SIMBAD, I excluded most of them because they had an average membership probability under 90%. That being said, the leftover stars had a relatively large amount of photometric data, which made guessing spectral types more or less straightforward.

Attached below is the Excel file I used to make it - this is for anyone who wants to see how exactly I did it.

Enjoy: