Photometric survey of the red giant V449 Cygni over half a century (1974 to 2022). A semi-regular variable star with a period of ~54 days

TL;DR

This paper presents a comprehensive 50-year photometric survey of the red giant V449 Cygni, revealing its transition from irregular to semi-regular variability with a consistent period of approximately 54 days, classifying it as an SRB-type star.

Contribution

It provides the first long-term analysis of V449 Cygni's variability, showing a shift from irregular to semi-regular behavior and identifying its classification as an SRB-type star.

Findings

V449 Cygni's variability changed from irregular to semi-regular.

The star has a stable period of about 54 days since mid-1990s.

Long-term variations may include a ~2000-day cycle.

Abstract

This study sums up a major part of the red giant V449 Cygni measurements for the years 1974 through 2022, obtained by visual and CCD GEOS observers, the Unione Astrofili Italiani, and various automatized telescopes. It appears that the light variations of V449 Cyg in the years 1970-1990 corresponded more to an L-type star according to the GCVS classification, with irregular amplitude variations, sometimes marked by a quasi-periodicity of about 100 days. Since the mid-1990s, these variations have become more regular, with an amplitude of about 0.7 magnitude in V, and a period of about 54,1 days, as shown by various period search routines applied to the best recent CCD series. A longer period of about 2000 days is possible to describe the long term variation of V449 Cyg. Therefore, V449 Cyg appears to be an SRB-type star.