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As the nearest known AGB star (d=64pc) and one of the brightest (mK-2), L2Pup is a particularly interesting benchmark object to monitor the final stagesof stellar evolution. We report new lucky imaging observations of this starwith the VLT/NACO adaptive optics system in twelve narrow band filters coveringthe 1.0-4.0 microns wavelength range. These diffraction limited images revealan extended circumstellar dust lane in front of the star, that exhibits a highopacity in the J band and becomes translucent in the H and K bands. In the Lband, extended thermal emission from the dust is detected. We reproduce theseobservations using Monte-Carlo radiative transfer modeling of a dust disk withthe RADMC-3D code. We also present new interferometric observations with theVLTI/VINCI and MIDI instruments. We measure in the K band an upper limit to thelimb-darkened angular diameter of theta_LD = 17.9 +/- 1.6 mas, converting to amaximum linear radius of R = 123 +/- 14 Rsun. Considering the geometry of theextended K band emission in the NACO images, this upper limit is probably closeto the actual angular diameter of the star. The position of L2 Pup in theHerzsprung-Russell diagram indicates that this star has a mass around 2 Msunand is probably experiencing an early stage of the asymptotic giant branch. Wedo not detect any stellar companion of L2 Pup in our adaptive optics andinterferometric observations, and we attribute its apparent astrometric wobblein the Hipparcos data to variable lighting effects on its circumstellarmaterial. We however do not exclude the presence of a binary companion, as thelarge loop structure extending to more than 10 AU to the North-East of the diskin our L band images may be the result of interaction between the stellar windof L2 Pup and a hidden secondary object. The geometric configuration that wepropose, with a large dust disk seen almost edge-on, appears particularlyfavorable to test and develop our understanding of the formation of bipolarnebulae.

An edge-on translucent dust disk around the nearest AGB star L2 Puppis - VLT/NACO spectro-imaging from 1.04 to 4.05 microns and VLTI interferometry