Beta Lyrae

Beta Lyr (blyr)

Semi-detached eclipsing binaries (also called beta Lyrae variables) are binary star systems (i.e. two stars that are in orbit around each other) that are aligned such that they eclipse each other relative to our line of sight from the Earth. Unlike detached EBs, semi-detatched systems are so close to each other that the shape of (at least one of) the stars in the system are distorted, giving rise to the smooth periodic variations even when the system is not eclipsing.

Classification and numbers

• Supertypes
• variable
• periodic
• binary
• eclipsing
• Occurrence rate: very common, about 10⁵ expected in ZTF data

ZTF light curves

Description

Any type of star can be in an eclipsing binary (so they may be small, large, hot, cool, etc.), which in turn can lead to a large range in eclipse amplitudes (though typically these are between 0.1 and ~1 mag, with most in the ~0.3 to 0.75 mag range) or eclipse periods (though our observations are typically only sensitive to periods between 0.1 to ~20 days).

Light curve characteristics

• periodic variable
• Range of amplitudes (~0.2 to >1 mag)
• Intermediate periods (log Period between -0.5 and 1.4)
• light curve shape: EB, round or sinusoidal light curves, with imposed "V-shape" dips in the phase folded light curve

References and further reading:

• Sterken & Jasschek: Light curves of variable stars