Toward Understanding the B [e] Phenomenon. VIII. Nature and Variability of IRAS 07080+0605

We report the results of spectroscopic and photometric observations of the emission-line object IRAS 07080+0605 carried out in 2004-2021. We found that the object is significantly underluminous for its spectroscopic properties (T-eff = 8500 +/- 500 K, log g = 2.0 +/- 0.5), if a strong visual attenuation by a factor of similar to 43 found through the spectral energy distribution modeling is not taken into account. Visual brightness variations with a stable period of 190 days but a variable amplitude of similar to 0.2 mag were found in the ASAS SN data and attributed to variable circumstellar extinction in the dusty disk. We also found that the observed behavior of IRAS 07080+0605 is similar to that of the protoplanetary nebula Red Rectangle. The dusty disk of IRAS 07080+0605 shows the presence of carbonaceous particles (similar to 10%-20% of the total dust content) and polycyclic aromatic hydrocarbon emission bands. However, IRAS 07080+0605 shows no obvious signs of the refractory element depletion, which is common in post-asymptotic giant branch (AGB) dusty binaries, or of a visual nebula. Absorption-line positions vary with an amplitude of similar to 25 km s(-1), suggesting the presence of a secondary component. Spectroscopic monitoring on a timescale from days to months is needed to search for regular variations. We conclude that IRAS 07080+0605 is most likely a binary system with an A-type component on its way toward the post-AGB evolutionary stage, as binarity is capable of explaining most of the observed features.

Automated summary

The results of spectroscopic and photometric observations of the emission-line object IRAS 07080+0605 are reported. The object shows underluminosity for its spectroscopic properties and exhibits periodic variations in visual brightness and absorption-line positions, indicating that it is most likely a binary system.