HK-band imaging polarimetry and radiative transfer modeling of the massive young stellar object CRL 2136

Abstract

Aims. We investigate the physical properties of the dust environment of the massive proto-stellar object CRL 2136 by means of two-dimensional radiative transfer modeling, which combines fitting of the spectral energy distribution, the intensity images, and the polarization images. Methods. We obtained polarimetric images of CRL 2136 in the H and K bands using the CIAO instrument on the 8 m Subaru telescope. We developed a new Monte Carlo code which can deal with multiple-grain models and computes the SED, the dust temperature, and the Stokes IQUV images. With this code, we performed two-dimensional modeling of CRL 2136’s circumstellar disk and envelope. Results. Our images show a compact infrared source, two bright lobes extending towards the south and east, and two faint lobes extending towards the northwest and west. The polarization images show a polarization disk near the central star with a position angle of ∼−135 ◦ , a polarization vector alignment approximately parallel to the polarization disk, and a region with low polarization between the eastern and the southern lobes. In our modeling, we assume three grain models: bare grains, warm grains with a crystalline water ice mantle, and cold grains with an amorphous water ice mantle. We obtained a maximum grain core size of 0.45 μm. We found that the CRL 2136 disk has a low disk mass of 0.007 M� , a large radius of 2000 AU, a scale height of 1.0, and a low accretion rate of ✭