UBV Photometry of the Post-AGB Star IRAS 22272+5435=V354 Lac in 1990-2008

TL;DR

This study presents 19 years of UBV photometry of the post-AGB star V354 Lac, revealing semi-regular pulsations with periods around 128 days, amplitude modulation, and stable mean brightness over nearly two decades.

Contribution

It provides long-term UBV photometric data and analysis of pulsation periods and spectral variations of V354 Lac, a post-AGB star, which was not previously documented over such an extended period.

Findings

Detected two close pulsation periods: 128 and 131 days.

Observed amplitude modulation due to period interference.

Found stable mean UBV magnitudes over 19 years.

Abstract

New UBV-photometry obtained in 2000-2008 is presented for the post-AGB star IRAS 22272+5435=V354 Lac. The star showed semi-regular light variations with varying amplitudes. The maximal amplitude did not exceed 0.5 in V-band. For 2000-2008, we have found a photometric period near 128 days. The analysis of long-term observations in 1990-2008 reveals variations with two close periods: 128 and 131 days, causing amplitude modulation. The V-(B-V) diagram shows a clear correlation: the star is generally bluer when brighter. From our UBV data, we derive E(B-V)=0.5 and conclude that the spectral type of the star varies between K1 to K7 during pulsations. The mean UBV-data of V354 Lac have not changed during the past 19 years: V=8.60, B-V=2.06 and U-B=2.14.