CT Lacertae: Another Long-period Carbon Star with Long-Timescale Variations?


Matthew R. Templeton
Peter Maurer
Wolfgang Kriebel
Wayne M. Lowder (1932–2003)
Etienne Morelle
Steve O’Connor
Andrzej Arminski
Laurent Bichon
John E. Bortle

AAVSO, 49 Bay State Road, Cambridge, MA 02138

Received August 11, 2014; revised September 9, 2014; accepted September 9, 2014


The poorly-studied semiregular-type variable CT Lacertae is a long-period variable of the carbon spectral type, and is also a member of the LPV subclass that exhibits double maxima. More importantly, CT Lac is also undergoing a long-timescale dimming episode spanning the last few thousand days. Analysis of the AAVSO’s 45-year visual light curve shows no clear changes in period during the course of its observational history, but current and past changes in mean light and amplitude suggest long-term, observable changes occur in the star itself or in its circumstellar environment. Long-term data are currently too short and sparse to say whether dimming episodes are cyclical as they are in some other long-period carbon Miras and semiregulars, but the ongoing dimming episode could be related to similar events which do recur in other long-period carbon stars like RU Vir and V Hya. CT Lac is an interesting variable and is recommended as a long-term target for both visual and instrumental observation. Increased visual observation is strongly encouraged, as are multicolor photometry and high resolution spectroscopy.