W Ursae Majoris star

astronomy

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Last updated

July 15, 2026

Quick Summary

W Ursae Majoris is a type of eclipsing binary star system. These systems consist of two stars that orbit each other so closely that they appear to be touching. From Earth's perspective, one star periodically passes in front of the other, causing a dip in the system's overall brightness.1

Eclipsing binaries are crucial for astronomers because they allow for the direct measurement of stellar masses, provided the orbital scale is known. The light curve, which plots the system's brightness over time, reveals details about the stars' sizes, luminosities, and the inclination of their orbits. W Ursae Majoris stars are a specific type of eclipsing binary where the stars are in very close contact, often with matter transferring between them.1

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Explosive variables
…from contact binaries of the W Ursae Majoris type, which are pairs of stars apparently similar to the Sun in size but revolving around one another while almost touching. One member may have reached the white dwarf stage. Matter fed to it from its distended companion appears to produce instabilities…
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…from contact binaries of the W Ursae Majoris type, which are pairs of stars apparently similar to the Sun in size but revolving around one another while almost touching. One member may have reached the white dwarf stage. Matter fed to it from its distended companion appears to produce instabilities…
Read More