Double stars best practice

[enzodbspace]

Hello!

What is the best practice for marking stars as double, so that they appear with the corresponding symbol? Is it possible to conditionally
change the star symbol? (If double, then...) I'm working with a filtered WDS catalog, and perhaps it can be cross-referenced with the star catalog data (like HIP) to flag the doubles.

The next question will be how to do the same with variables, and perhaps with double + variable 🤓

Best regards.

[steveberardi]

The standard way of plotting stars differently is to make multiple calls to the stars function, for example:

p.stars(where=[_.ccdm.isnull(), _.magnitude < 8])

# plot multiple star systems with the standard circle with a line through it symbol
p.stars(
  where=[_.ccdm.notnull(), _.magnitude < 8],
  style__marker__symbol="circle_line",
)

In the Tycho catalog (which is what the Big Sky catalog is based on), the CCDM identifies components of multiple star systems (so if the CCDM is not null, then it's a multiple star according to the Tycho catalog).

I remember seeing a cross reference for WDS and HIP/TYC, but it seems the WDS website is having some issues right now so I can't access it.

For variable stars, Starplot does have the standard symbol (circle with a solid dot inside), but the Big Sky catalog (and starplot's star model) does not keep track of variable stars yet. It's something I've been meaning to add :)

Handling multiple star systems and variables is something I'd definitely like to improve with starplot, so if you have any suggestions on how to make them easier to work with, let me know! Thanks!

Steve

[enzodbspace]

Thank you for the clear answer!

I think perhaps both approaches are possible: either the star is marked as a double star in the catalog (like your example), or a cross referenced catalog is used to mark it as a double star (the user must take certain precautions when constructing this catalog, to mark only the primary component of the system). A separated case to consider is adding the label with the ID of the WDS (sometimes along with the main ID of the star)

One detail I noticed is that when the symbol changes size (larger for brighter stars), the line crossing the star increases in thickness. I think the same happens with the central cross of globular clusters and the outer lines of planetary nebulae.

Best regards,

Enzo.

[steveberardi]

A separated case to consider is adding the label with the ID of the WDS (sometimes along with the main ID of the star)

You can do this in a kind of hacky way right now by defining a custom callable for star labels and using a lookup dictionary to get the WDS id. But, I'm also planning to add support for user-defined fields in catalogs (so for example, you'll be able to include the WDS id in a WDS catalog and then query on it and reference it on the star model itself).

One detail I noticed is that when the symbol changes size (larger for brighter stars), the line crossing the star increases in thickness. I think the same happens with the central cross of globular clusters and the outer lines of planetary nebulae.

Ah, yeah, I think this is a limitation of using Matplotlib as the rendering backend. One of my longer term goals with Starplot is to build a lightweight SVG backend that would be an alternative to Matplotlib and allow much more control over things like this.