You are here

The Avedisova catalog: A real Hitchhiker's Guide to the Galaxy?

Submitted by Kevin Jardine on 24 June, 2008 - 21:29

Modern telescopes and computing power have created an overwhelming amount of astronomical data. Almost 5 million objects are listed in the SIMBAD catalog. However, this is only a fraction of the data contained in more than 7000 astronomical catalogs. The largest of these, the Guide Star Catalog II, contains data on almost one billion objects.

This massive amount of information threatens to become a barrier to our understanding of our home galaxy, the Milky Way. We need something more detailed than the speculative schematic diagrams showing the bar, bulge and spiral arms, and yet more of a synthesis than is provided by a data dump of a billion objects.

We need a tour of the Milky Way by someone who has read all the major papers, studied all the major catalogs and can tell us what star cluster is part of what OB association which is embedded in what molecular clouds and ionises what nebulae. We need the highlights, and we need links to find more details if that interests us. We need, in short, a real Hitchhiker's Guide to the Galaxy.

While not as entertaining as Douglas Adam's fictional guide, there is at least the beginning of a detailed guide to the Milky Way, A Catalog of Star-Forming Regions in the Galaxy, released in 2002 and produced by Veta Avedisova and her colleagues at the Institute of Astronomy, Russian Academy of Sciences, in Moscow.

The Avedisova catalog contains information on about 3200 star formation regions. Quite a bit of information - it has over 66 thousand records listing observations of star clusters, molecular clouds, masers, nebulae, dust clouds and much more. Because it includes much of the latest data on infrared and radio sources, it is far more comprehensive than the Sharpless, Gum and RCW nebula catalogs compiled during the 1950s and complements and extends the optically visible OB associations studied by Ambartsumian, Ruprecht and Humphreys.

The Avedisova catalog can be accessed directly through the Vizier collection of astronomical catalogs. In order to make the catalog even easier to use, I've created a set of summary and index pages. There is an Avedisova summary page for each region listed in the catalog. Each page shows major information at the top, including IRAS and Westerhout sources, masers and well known objects such as Lynds dark nebulae, or Sharpless, Gum or RCW nebulae. The component listing below this gives the type of source, name (if provided) and bibliographic reference for each object whose observation data is contained in the catalog. You can dive straight into the catalog by clicking the region or component name. The source types are R (radio), O (optical), IR (infrared) and M (microwave/millimeter).

The summary pages tightly integrate the Avedisova catalog into the ADS and SIMBAD catalogs to link into the vast amount of astronomical information available online. I've replaced the Avedisova bibliographic codes with links directly into the ADS abstract system (I was able to find ADS abstracts for all but 9 of the 2441 sources cited in the Avedisova catalog). I've also looked up all the objects listed at the top of each summary page in SIMBAD. If more information is available in SIMBAD, I've linked directly to the SIMBAD page for that object. Next to each SIMBAD link, I've given the 6 character SIMBAD-provided object type and the number of bibliographic references. SIMBAD object types are not always accurate, so this information should be treated cautiously, but it is still useful, I think. A table converting the 6 character SIMBAD type codes into longer text can be found here. The number of bibliographic references gives a sense of how carefully studied that object is and how much information is available on it.

In order to make the catalog even more accessible, I've created three index systems. The first is a set of index pages that list all the galactic plane Avedisova regions (|b| Commentary on the Galactic Plane.

Second, I've created a similar set of pages that cross index the Avedisova regions with a number of well-known nebula catalogs, including the Sharpless, RCW, Lynds dark nebulae, Gum, BFS (Brand, Fich and Stark), Van den Bergh, Van den Bergh and Herbst, Bran and NGC catalogs.

I've also created cross indices for a number of more obscure objects that are important for estimating distances. These include the Wouterloot and Brand WB89 infrared sources, the Lockman compact radio HII regions, the Caswell/Haynes radio HII regions, and the SYCSW molecular clouds.

These cross references only scratch the surface of the full content of the Avedisova catalog, which contains a total of 38901 object references drawn from 2441 publications. (Not all these objects are distinct as often several publications reference the same object.) To give you a better idea of the scope of the catalog, I've created a (huge) page that lists the number of objects drawn from each publication here.

Third, I've created a mashup page combining the Avedisova regions with the astonishing Spitzer mosaic of the inner galaxy. The Avedisova catalog forms a useful guide to the Spitzer mosaic. The Avedisova regions are shown as yellow markers, and all the components for each region are displayed as orange markers at the most detailed zoom level. I've also displayed the locations of the Wolf-Rayet stars listed in van der Hucht's "The Seventh Catalogue of Galactic Wolf-Rayet stars" as red markers, and the supernova remnants from the catalog on Dave Green's website as green markers.

Clicking on each marker brings up a information window containing links for further information. It may take a minute for the markers to display, so please be patient.

The Avedisova regions are also displayed as markers at the higher zoom levels on the Milky Way Explorer.

The Avedisova catalog is an extremely useful resource for mapping the Milky Way and you can expect to see more resources based on it appearing on this site over time.