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We present Atacama Large Millimeter/submillimeter Array (ALMA) observationsat 0.3 arcsec-resolution of EX Lup, the prototype of the EXor class ofoutbursting pre-main sequence stars. The circumstellar disk of EX Lup isresolved for the first time in 1.3mm continuum emission and in the $J$=2--1spectral line of three isotopologues of CO. At the spatial resolution andsensitivity achieved, the compact dust continuum disk shows no indications ofclumps, fragments, or asymmetries above 5-sigma level. Radiative transfermodeling constrains the characteristic radius of the dust disk to 23 au and atotal dust mass of 1.0$\times$10$^{-4}$ M$_\odot$ (33 M_earth), similar toother EXor sources. The $^{13}$CO and C$^{18}$O line emission trace the diskrotation and are used to constrain the disk geometry, kinematics, and a totalgas disk mass of 5.1$\times$10$^{-4}$ M$_\odot$. The $^{12}$CO emission extendsout to a radius of 200 au and is asymmetric, with one side deviating fromKeplerian rotation. We detect blue-shifted, $^{12}$CO arc-like emission located0.8 arcsec to the north-west, and spatially disconnected from the diskemission. We interpret this extended structure as the brightened walls of acavity excavated by an outflow, which are more commonly seen in FUor sources.Such outflows have also been seen in the borderline FU/EXor object V1647 Ori,but not towards EXor objects. Our detection provides evidence that the outflowphenomenon persists into the EXor phase, suggesting that FUor and EXor objectsare a continuous population in which outflow activity declines with age, withtransitional objects such as EX Lup and V1647 Ori.

The Circumstellar Disk and Asymmetric outflow of the EX Lup Outburst System