We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array ( VLA ) with an angular resolution of \simeq 1 ^ { \prime \prime } .
We find that this object exhibits strong ( \simeq 4.4 mJy ) , unresolved ( \la 1 ^ { \prime \prime } ) 7 mm continuum emission , being one of the brightest isolated Herbig AeBe stars ever detected with the VLA at this wavelength .
No emission is detected at 3.5 cm continuum , with a 3 \sigma upper limit of \simeq 0.08 mJy .
From these values , we obtain a spectral index \alpha \ga 2.5 in the 3.5 cm to 7 mm wavelength range , indicating that the observed flux density at 7 mm is most likely dominated by thermal dust emission coming from a circumstellar disc .
We use available photometric data from the literature to model the spectral energy distribution ( SED ) of this object from radio to near-ultraviolet frequencies .
The observed SED can be understood in terms of an irradiated accretion disc with low mass accretion rate , \dot { M } _ { acc } \simeq 10 ^ { -8 } ~ { } M _ { \odot } yr ^ { -1 } , surrounding a star with an age of \simeq 10 Myr .
We infer that the mass of the disc is \simeq 0.04 M _ { \odot } , and is populated by dust grains that have grown to a maximum size of 1 mm everywhere , consistent with the lack of silicate 10 \mu m emission .
These features , as well as indications of settling in the wall at the dust destruction radius , led us to speculate the disc of HD169142 is in an advanced stage of dust evolution , particularly in its inner regions .