W UMa Stars

WUMa stars are low-mass, late-type contact binaries with short periods (of about 0.35 days) whose components typically have very different masses (with mass ratios around 0.3) but nearly identical temperatures (ΔT ≤ 200 K). As the temperature of a star is determined primarily by its mass, this property is paradoxical. It has been explained by the exchange of mass and energy through the common envelope.

Thanks to the small orbital separations, W UMa stars often display eclipses; at the same time, short periods make them attractive for observations with smaller ground-based instruments. Hundreds of these stars have been studied using the light-curve synthesis approach, which, combined with radial velocity measurements, allows the determination of the masses, radii, temperatures, and luminosities of the components. These quantities are invaluable, as they inform almost every area of astrophysics, particularly the studies of stellar structure and evolution.

While most of the above is true for all eclipsing binaries, W UMa stars have additional peculiarities that make them especially interesting. As a consequence of the common envelope, it is possible to derive a period-luminosity relation that makes W UMa stars competitive distance indicators. The common envelope also constrains the ratio of component radii in proportion to the ratio of their masses, allowing an indirect estimation of the absolute parameters from the light curves alone. With the present and future deluge of light curves from ground-based surveys and space telescopes, this property of W UMa stars is becoming increasingly important.


WUMaCat is the largest bibliographical compilation of physical parameters of W UMa stars made to date. It contains the data for nearly 700 individually studied objects gathered from more than 460 distinct publications, as well as additional data from the Gaia, LAMOST and Simbad archives.

This database is a companion to the paper describing the catalog and the statistical analysis of the collected data authored by Olivera Latković, Atila Čeki and Sanja Lazarević from Astronomical Observatory of Belgrade in Serbia. The paper has been published in Astrophysical Journal Supplement Series and can be accessed here. An ArXiv preprint is available as well.

For any questions or comments, please use the contact form to get in touch.

Thank you for visiting, and enjoy your stay!


Latković et al. 2021 ApJS 254 10

Website Version History

WUMaCat 1.9
March 1, 2024
Fixed a bug that prevented getting more (or fewer) than 10 similarity search results.
WUMaCat 1.8
June 16, 2023
Added the filtering function.
Added the ability to sort lists of stars.
Star search now returns a list of matching objects.
Added the ability to download lists generated by the filter and similarity search functions.
WUMaCat 1.7
November 7, 2022
Fixed an issue with how the distances were displayed in star details.
WUMaCat 1.6
July 14, 2021
Added the distribution plots.
WUMaCat 1.5
June 3, 2021
Added the violin plots and fixed the contact form.
WUMaCat 1.4
May 18, 2021
Added the HRD, PL, ML and MR plots.
WUMaCat 1.3
April 28, 2021
Site updated after the paper was published in ApJS.
Additional data from Gaia, LAMOST and Simbad made available for download.
WUMaCat 1.2
April 15, 2021
Added the year, title and author information from ADS to publication lists.
Updated the bibcodes of several papers that were only available on arXiv before.
WUMaCat 1.1
March 11, 2021
Site updated after the paper was accepted by ApJS.
WUMaCat 1.0
January 25, 2021
Site launch. Database corresponds to the data in the paper submitted to ApJS.