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HD 149427 is a very enigmatic object. It has been classified either as aplanetary nebula or as a D'-type symbiotic star. Its distance is also highlyuncertain. Furthermore, HD 149427 is a potential jet source. We report thenon-detection of X-ray emission from HD 149427 and explore the implications toits nature. We observed the object with XMM-Newton with an effective exposuretime of 33.5 ks. The upper limit for the flux of the X-ray emission in the softband (<2 keV) is 10^-15 erg/s/cm^2, while in the hard band (>2 keV) it is about10^-14 erg/s/cm^2. We discuss the implication of our results in light of thepossible natures of HD 149427 -- being a planetary nebula or a symbiotic star,close or very distant. The derived upper limits on the mass accretion rate ofthe white dwarf are untypical for symbiotic stars and may favor the picture ofHD 149427 being a young PN. HD 149427 might be a symbiotic star in hibernation-- if a symbiotic star at all. We estimate the possible mass-loss rate andkinetic luminosity of the jet and find no contradiction with our upper limit ofsoft X-ray emission. Therefore the jet may be still present but it was toofaint to be detected via soft X-ray emission.

Implications of the non-detection of X-ray emission from HD 149427