eclipsing binaries

O'Connell Effect Target List

The O’Connell effect is a phenomenon found in eclipsing binaries where the maxima between eclipses are not equally bright. It was first described by Roberts (1906), codified by O’Connell (1951), and named the O’Connell effect by Milone (1968). Despite being known for over a century, however, the physical processes underlying the O’Connell effect are still shrouded in mystery.

EB Zoo

The EB Zoo: examples of eclipsing binary stars and their behaviours

In this zoo, we will display not the specimen light curves of various types of EBs (these are readily available elsewhere), but the changes in their behavior.  Such changes are what most amateur observing programs aim to find and track.   Specifically, here are examples of EBs whose eclipses come early or late for different reasons, and a case where the eclipses no longer happen(!).


Campaign highlight: b Persei

Some of the best opportunities for contributing to astronomical research come through the AAVSO's Observing Campaigns, which are observing projects requested by individual researchers with a specific goal in mind. Some Campaigns are designed to last for a long time, and the results aren't known until well after the campaign concludes.  But some campaigns pay off immediately.  Our campaign on the bright star b Persei is an example of the latter, with a handful of AAVSO observers getting exactly the right data, at the right time, right away!

Nelson Database of Eclipsing Binary O-C Files

The late Bob Nelson developed over 5800 O-C (Observed - Computed) files for eclipsing binaries, all in Excel format, which we are hosting on our site. The purpose of this database is to provide information on period variation for selected eclipsing binaries (for astronomers interested in a particular star), as well as to determine the best elements for predicting future eclipses. These elements go into eclipse prediction software, like at Shawn Dvorak's site (Bob and others help provide updated elements for Shawn).

The Published Times of Minimum Database

The AAVSO now distributes its published times-of-minimum data for eclipsing binary in single compressed files (.tgz and .zip), rather than as a searchable online index.  For data on a specific star, unzip the compressed file, and search for the star's name among the included text files.  These files contain updated publication information through November 30, 2005, the time at which the files were last updated.