Algol-type binary stars

July meeting: Period Changes in Several Southern Eclipsing Binaries by Mark Blackford

Our meetings include brief business, a main presentation and items of astronomical news or learning from members. The July Main Item will be: Period Changes in Several Southern Eclipsing Binaries by Mark Blackford
(abstract below)

The July 2022 meeting is planned to be a face-to-face meeting; attendees can also join in online via Zoom. Details emailed to members. Guests/visitors can contact us for Zoom details at .
Any venue requirements re COVID-19 can be found here:

Visitors are welcome to join our face-to-face or online meetings.

Please stay home and attend online if you have any COVID-19 symptoms or are a close contact of a confirmed case of COVID-19.

Period Changes in Several Southern Eclipsing Binaries

Mark Blackford


Orbital period changes in close binary stars can be caused by a number of physical processes, including mass transfer from one component to the other or mass loss from the system as a whole through stellar winds. Observed minus Calculated (O-C) diagrams constructed from minima timings of eclipsing binary light curves provides a direct means of detecting and quantifying period changes. In this talk I will analyse O-C diagrams of several stars monitored as part of the Southern Eclipsing Binaries Project of Variable Stars South. True period change will be demonstrated in several cases as well as apparent period changes due to the presence of a third star or orbital precession in eccentric systems.

Southern variables in general are relatively understudied and amateurs using modest equipment can make significant contributions potentially leading to publication in astronomical journals.



09 Jul 2022


4:00 pm - 6:00 pm
Parnell Lecture Theatre 07-222


Parnell Lecture Theatre 07-222
Parnel Building, University of Queensland, St Lucia QLD 4067