Celestia Forums

Hi everyone!

After a few years of not updating my LMC and SMC add-on, I've finally made an update to it. At least, the "LMC" part of it. This is a pre-release: if you find any errors, please don't hesitate to tell me, so they can be fixed when this finally gets uploaded to the Motherlode.

This file adds over 77300 stars to the Large Magellanic Cloud. Like previous versions, the stars are real, and the data is from SIMBAD. The differences are:

- Obviously, way more stars: 77300 stars compared to 15600 stars in the LMC in the previous version.
- Improved structure: I looked at the latest research on the LMC's structure. The new version contains several features such as the LMC's bar, its inclination and position angle, and the 30 Doradus area being slightly farther away.
- Improved magnitudes and spectral type guesses: For many stars, V-magnitudes are estimated from magnitudes in other passbands, and for many stars, spectral types were guessed from color indices according to Eric Mamajek's stellar parameters table.
- A few objects, notably eclipsing binaries, have even more precise distances from distance moduli listed in the papers.
- More open clusters! This version contains 29, whereas the previous version only had 8. I've added some stars that are members of the open clusters, but not listed as children of the LMC. They are now also defined using the "OpenCluster" property in DSC files, making them easier to find.
- More globular clusters as well! The LMC now has 38, as opposed to 10 from the previous version. Structural parameters (core radii and the King concentration parameter, c) are more accurate.
- More pulsars than the previous version.
- More star systems, including several that are quite precise, due to detailed studies on them. Examples include OGLE LMC-CEP-227 and OGLE-LMC-CEP-2532.
- Best-estimate radii for stars larger than 1000 solar radii. I used a list maintained by fyr02.

Note that this add-on does not contain many of the brightest stars, unfortunately. This is because they are in the Tarantula Nebula. In the future I think I'll make a separate add-on for those stars.

Thank you to all that helped me by pointing me to research papers, including: Fafers_br, pedro_jg, SevenSpheres, Lafuente_Astronomy, and fyr02. Apologies if I forgot to add your name, please tell me if I do so.

Enjoy:

Added after 1 hour 3 minutes:
Fixed an error with [W60] A23, now the radius actually is used.

Maybe it’s worth introducing the "Replace" function for stars with HIP and TYC indices? This will eliminate potential duplicates with a two millionth base by ajtribick. The same thing with the Small Magellanic cloud.

Stars with HIP or TYC numbers are automatically replaced.

Wikibooks wrote:(Optional) Hipparcos catalog number: if this Hipparcos catalog number is the same as the Hipparcos catalog number of a previously existing Star or Barycenter, that object is replaced by this one. Barycenters and Stars can replace each other or objects of the same type.

SevenSpheres wrote:Hipparcos catalog number: if this Hipparcos catalog number is the same as the Hipparcos catalog number of a previously existing Star or Barycenter, that object is replaced by this one. Barycenters and Stars can replace each other or objects of the same type.

Wow. I didn't know about it. Very useful feature.

There is a potential issue with the HD and SAO names though. I set names to all the stars with HD and SAO designations. So for example HD 32034 is defined as:


But if you have ajtribick's hdindex.dat and saoindex.dat, which add HD and SAO designations for Tycho stars, then those designations will appear twice in Celestia.

If need arises, I may publish an alternative version that removes these names, so that they can be used alongside the new cross-index files.

LukeCEL wrote:If need arises, I may publish an alternative version that removes these names, so that they can be used alongside the new cross-index files.

If the problem exists, an alternative version may be needed.

Your new addon looks very “appetizing”. But I don’t have enough time to add it in the Origin until April 30, unless I sacrifice other tasks (what will not be). Therefore, you can continue to work in your rhythm.

LukeCEL wrote:Thank you to all that helped me by pointing me to research papers, including: Fafers_br, pedro_jg, SevenSpheres, Lafuente_Astronomy, and fyr02. Apologies if I forgot to add your name, please tell me if I do so.

Hmmmm, I did give some papers but not as good as the ones others have contributed. Not sure if I deserve credit. But hey, it's your call

Great job LukeCel.
And thanks for the kind citation.