  NGC 6302 is one of the highest ionization planetary nebulae known and shows
emission from species with ionization potential >300eV. The temperature of the
central star must be >200,000K to photoionize the nebula, and has been
suggested to be up to ~ 400,000K. On account of the dense dust and molecular
disc, the central star has not convincingly been directly imaged until now. NGC
6302 was imaged in six narrow band filters by Wide Field Camera 3 on HST as
part of the Servicing Mission 4 Early Release Observations. The central star is
directly detected for the first time, and is situated at the nebula centre on
the foreground side of the tilted equatorial disc. The magnitudes of the
central star have been reliably measured in two filters(F469N and F673N).
Assuming a hot black body, the reddening has been measured from the
(4688-6766\AA) colour and a value of c=3.1, A_v=6.6 mag determined. A G-K main
sequence binary companion can be excluded. The position of the star on the HR
diagram suggests a fairly massive PN central star of about 0.64,M_sun close to
the white dwarf cooling track. A fit to the evolutionary tracks for
(T,L,t)=(200,000K, 2000L_sun, 2200yr), where t is the nebular age, is obtained;
however the luminosity and temperature remain uncertain. The model tracks
predict that the star is rapidly evolving, and fading at a rate of almost 1 %
per year. Future observations could test this prediction.
