2024MNRAS.527.9263S

Central compact objects (CCOs), neutron stars found near the centre of some supernova remnants (SNRs), have been almost exclusively studied in X-rays and are thought to lack the wind nebulae typically seen around young, rotation-powered pulsars. We present the first, spatially resolved, morphological and spectroscopic study of the optical nebula observed at the location of CXOU J085201.4-461753, the CCO in the heart of the Vela Junior SNR. It is currently the only Galactic CCO with a spatially coincident nebula detected at optical wavelengths, whose exact nature remains uncertain. New Multi Unit Spectroscopic Explorer integral field spectroscopy data confirm that the nebula, shaped like a smooth blob extending 8 arcsec in diameter, is dominated by [N II]${\lambda } {\lambda }$6548, 6583 emission. The data reveal a distinct and previously unobserved morphology of the H ${\alpha }$ emission, exhibiting an arc-like shape reminiscent of a bow shock nebula. We observe a significantly strong [N II] emission relative to H ${\alpha }$, with the [N II]${\lambda } {\lambda }$6548, 6583 up to 34 times the intensity of the H ${\alpha }$ emission within the optical nebula environment. Notably, the [N II] and H ${\alpha }$ structures are not spatially coincident, with the [N II] nebula concentrated to the south of the CCO and delimited by the H ${\alpha }$ arc-like structure. We detect additional emission in [N I], He I, [S II], [Ar III], [Fe II], and [S III]. We discuss our findings in the light of a photoionization or Wolf-Rayet nebula, pointing to a very massive progenitor and further suggesting that very massive stars do not necessarily make black holes.