The First Study of a Period Change of the V1851 Orion Binary System

Abstract

V1851 Orion (V1851 Ori) is an eclipsing binary star which an orbital period of 0.27695 days. We use the 0.5 - meter reflecting telescope and CCD with the standard visual (V) and red (R) filters of the UBV system at the Regional Obser-vatory for the Public, Chachoengsao, Thailand, to observe their light curve. The photometry method calculates the light curves construction and the time of minimum determination. In this work, the time minimum of V1851 Ori is HJD 2458105.0490. The period change is calculated using the O-C diagram and it is shown that the period of the V1851 Ori is decreasing which the rate of 2 × (-6.75647 × 10-12) day/cycle. That means the period reduces continuously by approximately 1.54 × 10-3 seconds/year.

A Period Change Study of the Contact Binary System YY Eri

“…The time of minimum light from the YY Eri light curves was determined by differential equation theory [7] and constructed in the O-C diagram using the Wilson-Devinney software. It is derived from the linear ephemeris equation obtained from the Database of Eclipsing Binary O-C Files by Bob Nelson, AAVSO [8] as follows:…”