A New Candidate Luminous Blue Variable

Figer, Donald F.; Najarro, Francisco; Messineo, Maria; Clark, J. Simon and Menten, Karl M. (2020). A New Candidate Luminous Blue Variable. The Astrophysical Journal Letters, 901(1), article no. L15.

DOI: https://doi.org/10.3847/2041-8213/abb704

Abstract

We identify IRAS 16115−5044, which was previously classified as a protoplanetary nebula (PPN), as a candidate luminous blue variable (LBV). The star has high luminosity ( $^{>}_{\sim} 10^{5.75} \textit L _{\odot}$ ), ensuring supergiant status, has a temperature similar to LBVs, is photometrically and spectroscopically variable, and is surrounded by warm dust. Its near-infrared spectrum shows the presence of several lines of H I, He I, Fe II, Fe [II], Mg II, and Na I with shapes ranging from pure absorption and P Cygni profiles to full emission. These characteristics are often observed together in the relatively rare LBV class of stars, of which only ≈20 are known in the Galaxy. The key to the new classification is the fact that we compute a new distance and extinction that yields a luminosity significantly in excess of those for post-AGB PPNe, for which the initial masses are $<8 \textit M _{\odot}$ . Assuming single star evolution, we estimate an initial mass of $\approx 40 \textit M _{\odot}$ .