  We have imaged the disc of the young star HL Tau using the VLA at 1.3 cm,
with 0.08" resolution (as small as the orbit of Jupiter). The disc is around
half the stellar mass, assuming a canonical gas-mass conversion from the
measured mass in large dust grains. A simulation shows that such discs are
gravitationally unstable, and can fragment at radii of a few tens of AU to form
planets. The VLA image shows a compact feature in the disc at 65 AU radius
(confirming the `nebulosity' of Welch et al. 2004), which is interpreted as a
localised surface density enhancement representing a candidate proto-planet in
its earliest accretion phase. If correct, this is the first image of a low-mass
companion object seen together with the parent disc material out of which it is
forming. The object has an inferred gas plus dust mass of approximately 14
M(Jupiter), similar to the mass of a proto-planet formed in the simulation. The
disc instability may have been enhanced by a stellar flyby: the proper motion
of the nearby star XZ Tau shows it could have recently passed the HL Tau disc
as close as ~600 AU.
