Period Change Behavior of the Algol-Type Eclipsing Binary LS Persei (Abstract)

Volume 36 number 1 (2008)

Gary Billings

Abstract

(Abstract only) LS Persei is an Algol-type eclipsing binary, known to exhibit period change due to mass loss or transfer. Timings of its minima have been extended back to 1892 by archival observations in the Harvard College Observatory Photographic Plate Collection, and forward to 2007 by CCD observations. Over this interval, LS Per has undergone significant period decrease (ΔP/P = – 2.6 × 10–4, dP/dt = –2.0 × 10–8). Small period changes are hard to document due to the relatively large uncertainty of minima timings from plates and visual observations, but recent, higher precision, CCD timings establish at least one small period increase (ΔP/P = +1.5 × 10–5). The magnitude of this change, and the spectral type of the system, are compatible with the Applegate mechanism of periodic changes in the oblateness of the star which change the orbital period of the system. The ease with which high-precision minima timings can be obtained with a small telescope and CCD camera will allow early detection and close monitoring of future period changes.