A Multiwavelength Study of 1WGA 31346.5-6255: A New Y Cas Analog Unrelated to the Background Supernova Remnant G309.2-00.6

1WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. It appears to coincide with the bright and early-type star HD 119682, in the galactic open cluster NGC 5281. Its radio morphology, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 source and of a jetlike feature and break in the shell, suggest that 1WGA J1346.5-6255/G309.2-00.6 is a young analog of the microquasar powering the W50 nebula SS 433. This motivated us to study this source at X-ray and optical wavelengths. We present new Chandra observations of 1WGA J1346.5-6255, archival XMM-Newton observations of G309.2-00.6, and optical spectroscopic observations of HD 119682, to search for X-ray jets from 1WGA J1346.5-6255, study its association with the SNR, and test for whether HD 119682 represents its optical counterpart. We find no evidence for jets from 1WGA J1346.5-6255 down to an unabsorbed flux of 2.6 x 10 super(-13) ergs cm super(-2) s (0.5-7.5 keV), we rule out its association with G309.2-00.6, and we confirm that HD 119682 is its optical counterpart. We derive a distance of 1.2 plus or minus 0.3 kpc, consistent with the distance estimate to NGC 5281 (1.3 plus or minus 0.3 kpc), and much smaller than the distance derived to G309.2-00.6. We discuss the nature of the source, unveil that HD 119682 is a Be star, and suggest it is a new member of the recently proposed group of Y Cas analogs. The Chandra and XMM-Newton X-ray light curves show variability on timescales of hundreds of seconds, and the presence of a possible period of similar to 1500 s that could be the rotational period of an accreting neutron star or white dwarf in this y Cas analog.