A&A 492, 731-734 (2008)
Near-infrared multiwavelength imaging polarimetry of the low-mass proto-stellar object HL TauriK. Murakawa1, S. Oya2, T.-S. Pyo2, and M. Ishii2
1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2 Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku place, Hilo, HI 96720, USA
Received 31 July 2008 / Accepted 15 October 2008
We present the -band high-resolution polarimetric images of the low-mass proto-stellar object HL Tau using the adaptive optics-equipped CIAO instrument on the Subaru telescope. Our polarization images show a butterfly-shaped polarization disk with an extension. In the nebula, where polarization vectors are centro-symmetrically aligned, the polarization is as high as , , and . On the other hand, low polarizations of P<3% in the J, H, and K bands and a low color excess ratio of EJ-H/EH-K=1.1 compared to the standard cloud value of 1.75 are detected towards the central star. We estimated the upper limit of the grain sizes to be 0.4 m in the nebula and 0.7 m in the line of sight towards the central star. Our high-resolution polarimetric data, which spatially resolves the polarization disk, provides us with important information about grain growth in the region close to the central star.
Key words: polarization -- ISM: dust, extinction
© ESO 2008