Hubble Space Telescope WFPC2 imaging of the and jet of HV Tauri C.
STAPELFELDT K.R., MENARD F., WATSON A.M., KRIST J.E., DOUGADOS C., PADGETT D.L. and BRANDNER W.
Abstract (from CDS):
We have obtained Hubble Space Telescope (HST) WFPC2 images of the HV Tauri young triple system. The tertiary star appears as a compact bipolar nebula at visual wavelengths as already known in the near-infrared. New, deeper adaptive optics observations made at the Canada-France-Hawaii Telescope show no point source in the nebula to a limiting magnitude of K>15. The results therefore confirm that HV Tau C is an optically thick circumstellar disk seen close to edge-on. Clear evidence for small, chromatic dust particles in the outer disk is provided by the color structure of the nebula: the thickness of the central dust lane shrinks by 30% between 0.55 and 2.2 µm. Bipolar jets extending 0".3-0".7 perpendicular to the dust lane are seen in HST narrowband [S II] and [O I] images. The continuum images are compared to multiple scattering models, with optimal density model parameters derived through χ2 minimization. A disk density distribution provides a reasonable fit to the K-band image but is unable to reproduce the vertical extent of the nebula at I band without resorting to an unreasonably large scale height. Adding an envelope structure around the disk results in a much better fit to the HST image, and with a physically reasonable disk scale height. Our preferred model has a disk outer radius of 50 AU, inclination of 6°, and scale height of 6.5 AU at r=50 AU. The thickness of the dark lane establishes a disk mass near 2x10–3M☉(∼2MJup) of dust and gas, if the dust grains have interstellar properties and remain fully mixed vertically. The envelope, with a much smaller mass ∼4x10–5M☉, would be very short-lived unless replenished by new material from the star or surrounding medium.