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AAVSO / VStar

VStar is a visualisation and analysis tool for variable star data brought to you by AAVSO
https://www.aavso.org/vstar
GNU Affero General Public License v3.0
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Permit arbitrary function in Leavitt's Law plug-in #86

Open dbenn opened 3 years ago

dbenn commented 3 years ago

Add an option to allow a user-defined VeLa function to be used for the Period-Luminosity relationship. This will allow distance determination for other stars, e.g. RR Lyr, DSCT.

Indeed, the existing DCEP function could be exposed as a VeLa function, allowing arbitrary modification. Useful at least for educational purposes. The special DCEP selector would give way to a VeLa function that can be edited. Indeed, instead of a function, the only real requirement is a distance variable as the end result. A name would need to be agreed upon.

A wiki page with distance calculation recipes for object types could be created.

An option is to allow VeLa code to be saved for different object types, e.g. via the Preferences mechanism or more simply, as VeLa scripts that can be loaded, perhaps with a standard file location. This also suggests the idea that a per-plugin directory could be introduced in general.

See also my post to the AAVSO short-period pulsators forum to seek input re: this: https://www.aavso.org/period-luminosity-relation-rr-lyr

dbenn commented 3 years ago

Jean-Bruno Desrosiers writes in email (Nov 22 2020):

I might also have something that would interest you in relation to one of your recent 'posts' on the calculus of Cepheids: http://www.aavso.org/period-luminosity-relation-rr-lyr

I had a method from the director of the Observatory of Mont Mégantic, a simple calculation (See the attached document, the first part is in French, page 2 in English). This little document was written in the spring of 2020, when I co-facilitated the AAVSO course "Classification of variable stars and light curves".

In the same way, I put a article on my web site: http://omsj.info/index.php/activites/chroniques/109-les-cepheides-comment-calculer-les-distances It's in french, but you can traduce in english easily with Google translation.

I believe that for type two Cepheids (W vir and RR Lyrae), the factor '5' could be changed to "4.5" but it would be necessary to make tests to have a more precise output. This is what I proposed as a project for 2021. Same thing, the same calculation can be applied for SN1a because we know that the magnitude of 1a is relatively stable at -19.4.

If that can help you, that would make me happy.

dbenn commented 3 months ago

This could also be extended to novae although there are two pieces of information required for that (at least):

  1. peak apparent magnitude (vs mean)
  2. rate of decline

So, a separate plugin makes sense for that.

See https://arxiv.org/pdf/1703.04087