Near-Infrared and X-Ray Observations of the Enigmatic G70.7+1.2

Abstract

We present high-resolution imaging of the puzzling radio and optical nebula G70.7+1.2 with the Keck Observatory's laser guide star adaptive optics (LGS-AO) system and the Chandra X-Ray Observatory. The archival X-ray observations show a hard (Γ ≈ 1.8), low-luminosity (L_X ≈ 4 × 10^(31) ergs s^(-1)) point source at the center of the nebula. Follow-up LGS-AO near-infrared imaging of the Chandra error circle reveals a relatively bright (K' ≈ 14 mag) counterpart. Both its color and brightness are consistent with a heavily obscured B star or possibly a late G/early K giant. The most plausible explanation is that this newly discovered X-ray source is a nonaccreting B star/pulsar binary powering the radio and optical nebula. If so, the luminous Be star discussed in the literature seemingly embedded in the nebula is not the dominant force responsible for shaping G70.7+1.2. Thus, we suggest that G70.7+1.2 is the result of two unrelated objects (a B star X-ray binary and a Be star) interacting with a dense molecular cloud. With this explanation we believe we have solved the mystery of the origin of G70.7+1.2.

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