astrolabium is an MIT python project that aims to automatically parse existing star catalogues (like the Hipparcos, Gliese, WDS catalogues) and create a human-readable json file that describes a set of star systems that fulfill the desired conditions, including the hierarchy in case of double or multiple star systems.
It was developed for use in a Space Exploration game I am developing, Sine Fine.
- Parses the Hipparcos 2 catalogue.
- Parses the Washington Double Star catalog to retrieve information on physical double stars.
- Parses the Sixth Catalog of Orbits of Visual Binary Stars to retrieve information on the orbit of double stars.
- Creates a cross reference table joining multiple catalogues together. For example, the Hipparcos catalogue with information from Simbad to combine stars with other catalogue descriptors.
- Queries Simbad to obtain other data about each star.
- Queries Wikidata to retrieve data that is typically not available in catalogues, like estimated mass, temperature, luminosity.
- Combines all these information into a catalogue file.
A json file that preserves the hierarchy of the star system and provides all the data it was able to find. For example, here is Alpha Centauri. For more information on how it reconstructs the hierarchy, see below.
"Alpha Centauri": {
"Name": "Alpha Centauri",
"Orbiters": {
"A": {
"Id": "HIP 71683",
"Name": "Rigel Kentaurus",
"SC": "G2V",
"Orbiters": {
"C": {
"Id": "HIP 70890",
"Name": "Proxima",
"SC": "M5Ve",
"OrbitalData": {
"a": 14666.424758,
"P": 547000.0,
"e": 0.5,
"i": 107.6,
"lan": 126.0,
"argp": 72.3
}
}
}
},
"B": {
"Id": "HIP 71681",
"Name": "Toliman",
"SC": "K1V",
"OrbitalData": {
"a": 22.160317,
"P": 79.91,
"e": 0.524,
"i": 79.32,
"lan": 204.75,
"argp": 232.3
}
}
},
"c": "0.948784, -0.924527, -0.015823"
},pip install astrolabium
In your project create a python script and write the following:
from astrolabium.creator import CatalogueCreator
# You can disable this next line once it has run the first time
CatalogueCreator.download_and_parse_catalogues()
# This will select all single and multiple star systems within 100 light years
cat = CatalogueCreator(lyr=100)
cat.create()You will then find a file named catalogue_100_ly.json in the out/ folder. With the default settings it will select all single and multiple star systems within a distance of 100 light years that have either a Bayer or Flamsteed designation (so Alpha Centauri and 61 Cygni will be included but not HIP 12345). You can pass an array of filters to create() to choose which systems should be included for each of the single and multiple star systems sets.
astrolabium works by combining different catalogues together. Currently, the starting point is the Hipparcos 2 catalogue. It works as follows:
- By using the
find_single_starsmethod you can pass an array of filters. - It then removes all stars that have an entry in the
WDScatalogue (meaning this could be a candidate for a multiple star system). - You can then call the
find_multiple_systems. It will look for all entries that have aWDScatalogue id among those that are also present in the Hipparcos catalogue. - It will then try to analse corresponding entries in the
WDScatalogue to deduce the hierarchy of the star system and match each star to an entry in the Hipparcos catalogue and and an orbit from theOrb6catalogue, if present. - The output of both function is a list of
Systemobject that is then combined into aGalaxyobject and saved to disk.
The WDS catalogue provides a list of entries of potential double stars. However, not all entries refer to a component of a multiple star system. Each entries refers to a pair of stars. For example the Alpha Centauri system, consists of three stars. In the WDS catalogue there are three entries for the A,B and A, C with A referring to the primary star, Rigil Kentaurus, B referring to the companion Toliman and C referring to Proxima Centauri. A third entry refers a Ca,Cb pair, which could have indicate the presence of a fourth component star. The notes of the catalogue indicate that it was not indeed a physical binary, and it might refer to a substellar companion (a planet).
To distinguish between visual binaries (stars that appear close but are far away from each other) and physical binaries (pairs that are gravitationally bound), the notes field of the WDS catalogue is used. The class WDSAnalyser can also be used to query a specific star system. For example, calling query_system and using the WDS id for Alpha Centauri 14396-6050 will result into this output (if the object is created with the verbose option):
*
├── A
│ └── C
└── B
However, the C-component, Proxima is a distant companion ordering the AB pair as a group. But there was no easy way to indicate this in json. To avoid overcomplicating things, these components are assigned as "children" of the primary component of the pair.
astrolabium is able to retrieve missing data from Wikidata, such as a star's mass, luminosity, temperature, etc. To be able to do this, you would need to retrieve this data from Wikidata.
- You can use the file
entities/Hipparcos_entities.jsonprovided in this repo, which contains all data retrieved from Wikidata for each of the stars that appear in theHipparcos 2catalogue. You can recreate it with theWikidataandWikiEntitiesclasses inastrolabium.queries, but it will take hours. - The file
entities/IAU_entities.jsoncontains the same but for only the stars that have a proper name, as defined by the IAU.
You can download one or both and then copy them to your own entities/ folder. The two files in the data/ folder contain a dictionary of all wikidata qids for the stars in that catalogue for further analysis. See the methods in the Wikidata and WikiEntities classes in astrolabium.queries.
- Include support for updating the catalogue data with the Gaia DR3 dataset, which may contain more up-to-date and accurate measurements of parallaxes and other data.
- Include support for parsing the NASA JPL Horizons data for Solar System objects.
- Include support for the Open Exoplanet Database.
- Include support for the Tycho catalogue.