We present near-infrared polarimetric images of the dusty circumstellar envelope ( CSE ) of IRAS 19306+1407 , acquired at the United Kingdom Infrared Telescope ( UKIRT ) using the UKIRT 1-5 \mu m Imager Spectrometer ( UIST ) in conjunction with the half-waveplate module IRPOL2 .
We present additional 450 and 850 \mu m photometry obtained with the Sub-mm Common User Bolometer Array ( SCUBA ) at the James Clerk Maxwell Telescope ( JCMT ) , as well as archived Hubble Space Telescope ( HST ) F606W - and F814W -filter images .
The CSE structure in polarized flux at J- and K- bands shows an elongation NNE-SSW with two bright scattering shoulders NW-SE .
These features are not perpendicular to each other and could signify a recent ‘ twist ’ in the outflow axis .
We model the CSE using an axisymmetric light scattering ( ALS ) code to investigate the polarization produced by the CSE , and an axisymmetric radiation transport ( DART ) code to fit the SED .
A good fit was achieved with the ALS and DART models using silicate grains , 0.1-0.4 \mu m with a power-law size distribution of a ^ { -3.5 } , and an axisymmetric shell geometry with an equator-to-pole contrast of 7:1 .
The spectral type of the central star is determined to be B1 I supporting previous suggestions that the object is an early PN .
We have constrained the CSE and interstellar extinction as 2.0 and 4.2 mag respectively , and have estimated a distance of 2.7 kpc .
At this distance the stellar luminosity is \sim 4500 L _ { \sun } and the mass of the CSE \sim 0.2 M _ { \sun } .
We also determine that the mass loss lasted \sim 5300 yrs with a mass-loss rate of \sim 3.4 \times 10 ^ { -5 } M _ { \sun } yr ^ { -1 } .