Pulsations and long-term photometric variability of three candidates for protoplanetary nebulae |
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| Authors: | V P Arkhipova N P Ikonnikova G V Komissarova |
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| Institution: | 1.Sternberg Astronomical Institute,Moscow,Russia |
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| Abstract: | We present new photometric data and analyze long-term UBV observations of three candidates for protoplanetary nebulae—F supergiants with infrared excesses at high Galactic latitudes—IRAS
18095+2704, IRAS 19386+0155, and IRAS 19500-1709. All these stars exhibit quasi-periodic low-amplitude variations caused by
pulsations against the background of long-term brightness trends. For IRAS 18095+2704=V887 Her, we have found a pulsation
period of 109 days and revealed a linear brightness trend—the star brightens at constant (within the limits of the measurement
errors) yearly mean color indices. The light curve of IRAS 19386+0155=V1648 Aql in 2000–2008 is represented by a wave with
a fundamental period of 102 days whose modulation with a close period of 98 days leads to variations with a variable amplitude.
V1648 Aql also shows a systematic rise in V brightness along with a reddening. IRAS 19500–1709=V5112 Sgr exhibits irregular pulsations with periods of 39 and 47 days.
The long-term variability component of V5112 Sgr may indicate that the star is binary. |
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