* Astronomy

Title: MN112: a new Galactic candidate Luminous Blue Variable
Authors: V.V.Gvaramadze, A.Y.Kniazev, S.Fabrika, O.Sholukhova, L.N.Berdnikov, A.M.Cherepashchuk, A.V.Zharova

We report the discovery of a new Galactic candidate Luminous Blue Variable (cLBV) via detection of an infrared circular nebula and follow-up spectroscopy of its central star. The nebula, MN112, is one of many dozens of circular nebulae detected at 24 \mu m the Spitzer Space Telescope archival data, whose morphology is similar to that of nebulae associated with known (c)LBVs and related evolved massive stars. Specifically, the core-halo morphology of MN112 bears a striking resemblance to the circumstellar nebula associated with the Galactic cLBV GAL 079.29+00.46, which suggests that both nebulae might have a similar origin and that the central star of MN112 is a LBV. The spectroscopy of the central star showed that its spectrum is almost identical to that of the bona fide LBV P Cygni, which also supports the LBV classification of the object. To further constrain the nature of MN112, we searched for signatures of possible high-amplitude (\ga 1 mag) photometric variability of the central star using archival and newly obtained photometric data covering a 45 year period. We found that the B magnitude of the star was constant (\simeq 17.1±0.3 mag) over this period, while in the I band the star brightened by \simeq 0.4 mag during the last 17 years. Although the non-detection of large photometric variability leads us to use the prefix 'candidate' in the classification of MN112, we remind that the long-term photometric stability is not unusual for genuine LBVs and that the brightness of P Cygni remains relatively stable during the last three centuries.

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