Simultaneous optical speckle masking and NIR adaptive optics imaging of the 126 mas Herbig Ae/Be binary star NX Puppis

We present simultaneous optical and near-infrared high angular resolution observations of the close Herbig Ae/Be binary star NX Pup which is associated with cometary globule 1. The reconstructed images have a diffraction–limited resolution of 62 mas in V, 75 mas in R (speckle masking reconstruction), and 115 mas in H, 156 mas in K (adaptive optics + post–processing). Compared to previous results we were able to derive better estimates on spectral type and luminosity and hence put better constraints on the evolutionary status (mass & age) of NX Pup A and B: with NX Pup A of spectral type F0-F2 we estimate the spectral type of NX Pup B in the range F7-G4, masses of 2 M⊙ and 1.6–1.9 M⊙, respectively, and an age of 3–5 Myr for both stars. We discuss the implication of the new age determination on the physical relation between NX Pup and the cometary globule. The dynamical lifetime of ≈ 10 yr for cometary globule 1 suggests that cometary globule 1 and the nearby cometary globule 2 represent transient phenomena and are left overs of a larger molecular cloud which in turn was the parental cloud of NX Pup A and B and finally got dispersed by photoevaporation. The IR excess of NX Pup A can be modeled by a viscous accretion disk, which is cut off at ≈ 20 AU from the star. NX Pup B has a smaller IR excess which indicates that there is less circumstellar material present than around the primary.