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We present continuum and molecular line (CO, C$^{18}$O, HCO$^+$) observationscarried out with the Atacama Large Millimeter/submillimeter Array toward the"water fountain" star IRAS 15103-5754, an object that could be the youngest PNknown. We detect two continuum sources, separated by $0.39\pm 0.03$ arcsec. Theemission from the brighter source seems to arise mainly from ionized gas, thusconfirming the PN nature of the object. The molecular line emission isdominated by a circumstellar torus with a diameter of $\simeq 0.6$ arcsec (2000au) and expanding at $\simeq 23$ km s$^{-1}$. We see at least two gas outflows.The highest-velocity outflow (deprojected velocities up to 250 km s$^{-1}$),traced by the CO lines, shows a biconical morphology, whose axis is misaligned$\simeq 14^\circ$ with respect to the symmetry axis of the torus, and with adifferent central velocity (by $\simeq 8$ km s$^{-1}$). An additionalhigh-density outflow (traced by HCO$^+$) is oriented nearly perpendicular tothe torus. We speculate that IRAS 15103-5754 was a triple stellar system thatwent through a common envelope phase, and one of the components was ejected inthis process. A subsequent low-collimation wind from the remaining binarystripped out gas from the torus, creating the conical outflow. The highvelocity of the outflow suggests that the momentum transfer from the wind wasextremely efficient, or that we are witnessing a very energetic mass-lossevent.

ALMA imaging of the nascent planetary nebula IRAS 15103-5754