Hubble Space TelescopeObservations of the Disk and Jet of HH 30

Abstract

HH 30 in Taurus has been imaged with the Hubble Space T elescope WFPC2. The images show in reÑected light a Ñared disk with a radius of about 250 AU that obscures the protostar. The disk resembles detailed accretion disk models that constrain its density distribution and show that its inclination is less than 10¡. There are bipolar emission-line jets perpendicular to the disk, a very clear demonstration of the standard paradigm for accretion disk and jet systems. However, asymmetries in the light distribution show that the disk has not completely settled into a quasi-equilibrium accretion state, or that some of the observed scattering is from an asymmetric envelope. The emission-line jet itself is resolved into a number of knots with typical lengths and separations of much smaller and more numerous than 0A .4, indicated by lower resolution ground-based studies. There are indications of still Ðner structures in the jet all the way to the resolution limit ofThe knots have proper motions ranging from 100 to 300 0A .1. km s~1 and are therefore generated at the surprisingly high rate of about 0.4 knots per jet per year. The jet appears to be collimated within a cone of opening angle 3¡ and can be seen to within 30 AU of the star.Both single-and multiple-scattering disk models have a range of possible solutions, but by requiring pressure support and temperature equilibrium, a self-consistent model emerges. There is evidence for pressure support because the disk appears to have a Gaussian height proÐle. The temperature at each point in the disk is determined by the disk geometry, which in turn Ðxes the temperature in a selfconsistent manner. The extinction to the protostar is unknown but constrained to be greater than 24 mag. The optical properties of the scattering grains in the disk are determined and found to imply a large scattering asymmetry, but they seem to follow the interstellar reddening law. The absolute magnitude and colors of the unseen protostar, which has a brightness in the I bandpass of about 0.16 times solar and is very red, are obtained. The disk mass is about 0.006 times solar and has an expected lifetime of about 105 yr.

Visions of Nature's Planet Foundry: Images of Circumstellar Disks

“…Flaring (i.e., increasing disk thickness with radius) is now directly observed in young stellar object disks. Detailed studies of the HH 30 disk indicate a Gaussian vertical profile with a scale height comparable to that expected from local thermal equilibrium (4,50). However, a smaller than expected scale height has been measured in the disk of HK Tau B (46), possibly indicating that the dust has settled with respect to the gas in this disk.…”

“…Each panel is labeled with the object name, wavelength, and the size of the image field of view. From left to right in each row, the image sources are references top: (13), (3), (33); center: (23), (15), (14); and bottom: (35), (4), (4).…”

“…Subsequent kinematic studies of millimeter molecular line emission were instrumental in showing that disk gas moves in Keplerian orbits about the central star (9,16,30). The advent of the Hubble Space Telescope (HST) rejuvenated optical disk imaging (3,4,18), and together with adaptive optics (AO) on large ground-based telescopes, has provided images of several young disks in the near-infrared (35,39; 37,33). Finally, high-resolution thermal infrared imaging has begun to make important contributions to the field (20,23).…”

Early Orbital Evolution of Binaries: Overview and Outlook

“…close binary stars and planets) is always closely associated with the presence of accretion disks (e.g., McCaughrean & O'Dell 1996;Burrows et al 1996;Stapelfeldt et al 1998). A clear decrease with time of the fraction of optically thick disks (at <3 AU from the star) from rvl00% at the age rvO.3 Myr down to a few percent at the age of rvl0 Myr has been demonstrated by Hillenbrand & Meyer (1999).…”

On the time variability of the HH jet ejection process

“…The HH30 jet moves nearly on the plane of the sky, has a clear side-to-side symmetry in the region close to the central star, and the cooling region is resolved spatially with Hubble Space Telescope (HST) observations (e.g. Burrows et al 1996, Ray et al 1996, Bacciotti et al 1999, Hartigan & Morse 2007. Assuming that the HH30 jet is axisymmetric, we showed in a previous work (De Colle et al 2010) that standard tomographic techniques may be employed to recover the three-dimensional structure of the jets.…”