Dimming Stars that enlighten our understanding of stellar evolution
What We Do
Eclipsing binaries are pairs of stars whose orbital plane is aligned so that, from Earth, one star passes in front of the other, causing periodic dips in brightness. By observing these systems, we can measure their light variations and determine precise times of minima (ToM), orbital periods, and other physical properties.
Your observations, combined with data from other observers worldwide, contribute to ongoing scientific studies of stellar evolution, mass transfer, and orbital dynamics. The data are archived in the AAVSO database and used in publications and O–C (Observed minus Calculated) analyses.
This long-term monitoring allows astronomers to compare present-day behavior with historical observations, enabling the study of changes in orbital periods and other stellar properties over decades.
How We Do It
Observing eclipsing binaries involves measuring the brightness of stars over time. Most observers do photometry recording a series of images through a telescope with a CCD or CMOS camera, reducing the images using software, and calculating the brightness of the target relative to comparison stars.
For visual observing, observers monitor the target using naked eye, binoculars or telescope and estimate the brightness relative to nearby comparison stars. Visual observations focus on a limited number of systems which have eclipses deeper than 1 or 2 magnitudes.
Once your observation reports are prepared, they are submitted to the AAVSO database. Observers can also calculate times of minima and contribute to O–C analyses, helping track period changes and stellar activity cycles. Comprehensive guides and tutorials are available for all levels of observers.
Is It Right for Me?
Level: Moderate. Eclipsing binary observing requires some familiarity with photometry for most systems, though a few bright binaries can be monitored visually.
Equipment: Photometric observing: A small telescope (4–8 inch aperture) with CCD or DSLR camera. Filters (V, R, or I) are recommended for standard photometry. Visual observing: A small telescope or binoculars can be used, but only a limited number of brighter systems are suitable.
Observing Requirements: Observations typically involve monitoring the system for several hours during an eclipse. Visual observing requires careful attention to timing and brightness estimates.
Additional Considerations: Data reduction software is required for photometric observations (e.g., VPhot). In all cases it is recommended to focus on the steepest portions of the eclipse for a better Time of Minimum (ToM). Standardized submission procedures must be followed for inclusion in the AAVSO database.
Image Credit: ESO/L. Calçada