Long-term luminosity variations and period changes in CG Cygni^*

¹ Ege University, Science Faculty, Department of Astronomy and Space Sciences, Bornava, Izmir 35100, Turkey e-mail: ibanoglu@astronomy.sci.ege.edu.tr
² Western Carolina University, Department of Chemistry and Physics, Cullowhee, NC 28723, USA e-mail: heckert@email.wcu.edu

Corresponding author: M. Afşar, afsar@astronomy.sci.ege.edu.tr

Received: 27 August 2003
Accepted: 16 February 2004

Abstract

We report new photometry of CG Cyg from 1998–2002. We also analyze published photometry collected since 1965. An O–C analysis reveals evidence of a third body in the system having a 51 year orbital period. After removing the effects of the third body, we note a remaining 22.5 year cyclic variation in the O–C curve that is similar to the period of the luminosity variations. Modeling the spot activity for 28 V band light curves obtained between 1965 and 2002 confirms the presence of two active longitude belts (ALBs) at approximately and . Most of the spots occur at mid latitudes with a few at low latitudes. We note no spots at latitudes greater than .