We present high angular resolution observations , taken with the Very Large Array ( VLA ) and Multiple Element Radio Linked Interferometer Network ( MERLIN ) radio telescopes , at 7 mm and 4.4 cm respectively , of the prototype Class 0 protostar VLA1623 .
At 7 mm we detect two sources ( VLA1623A & B ) coincident with the two previously detected components at the centre of this system .
The separation between the two is 1.2 arcsec , or \sim 170 AU at an assumed distance of 139 pc .
The upper limit to the size of the source coincident with each component of VLA1623 is \sim 0.7 arcsec , in agreement with previous findings .
This corresponds to a diameter of \sim 100 AU at an assumed distance of 139 pc .
Both components show the same general trend in their broadband continuum spectra , of a steeper dust continuum spectrum shortward of 7 mm and a flatter spectrum longward of this .

We estimate an upper limit to the VLA1623A disc mass of \leq 0.13 M _ { \odot } and an upper limit to its radius of \sim 50 AU .
The longer wavelength data have a spectral index of \alpha \sim 0.6 \pm 0.3 .
This is too steep to be explained by optically thin free-free emission .
It is most likely due to optically thick free-free emission .
Alternatively , we speculate that it might be due to the formation of larger grains or planetesimals in the circumstellar disc .
We estimate the mass of VLA1623B to be \leq 0.15 M _ { \odot } .
We can place a lower limit to its size of \sim 30 \times 7 AU , and an upper limit to its diameter of \sim 100 AU .
The longer wavelength data of VLA1623B also have a spectral index of \alpha \sim 0.6 \pm 0.3 .
The nature of VLA1623B remains a matter of debate .
It could be a binary companion to the protostar , or a knot in the radio jet from VLA1623A .