An Infrared Ring Nebula around MSX5C G358.5391+00.1305: The True Nature of Suspected Planetary Nebula Wray 17‐96 Determined via Direct Imaging and Spectroscopy

Abstract

The Midcourse Space Experiment (MSX) Galactic plane survey discovered a nearly perfectly circular ring nebula around the suspected planetary nebula Wray 17-96. Using near-IR spectral typing and modeling of the mid-IR nebula, we find that Wray 17-96 is more likely a candidate to be a luminous blue variable (LBV) surrounded by a large spherical ejecta shell. It is very similar to the G79.29+0.46 LBV candidate in Cygnus and the Pistol Star. The K-band spectrum and the mid-IR data indicate a stellar temperature of 13,000 K. The most likely distance to the source is 4.5 kpc, leading to a luminosity of 1.8 × 106 L☉. We suggest that the nebula consists of multiple shells and that an evolution from oxygen-rich to carbon-rich chemistry may be indicated.