High‐Resolution Near‐Infrared Images and Models of the Circumstellar Disk in HH 30

Abstract

We present Hubble Space T elescope near-infrared camera and multiobject spectrometer observations of the reÑection nebulosity associated with the T Tauri star HH 30. The images show the scattered-light pattern characteristic of a highly inclined, optically thick disk with a prominent dust lane whose width decreases with increasing wavelength. The reÑected nebulosity exhibits a lateral asymmetry in the upper lobe on the opposite side to that reported in previously published Wide Field Planetary Camera 2 images. The radiation transfer model that most closely reproduces the data has a Ñared accretion disk with dust grains larger than standard interstellar medium grains by a factor of approximately 2.1. A single hot spot on the stellar surface provides the necessary asymmetry to Ðt the images and is consistent with previous modeling of the light curve and images. Photometric analysis results in an estimated extinction of however, since the photometry measures only scattered light rather than direct A V Z 80 ; stellar Ñux, this a lower limit. The radiative transfer models require an extinction of A V \ 7900.

A multiple system of high-mass YSOs surrounded by disks in NGC 7538 IRS1

“…(23) it is also clear that the opening angle α of the disk around IRS1b has to be large enough (α ≈ 45 • ) to ensure that the gas density does not exceed the threshold for the thermal quenching even at R ≥ R 0 . Such a geometry reminds the profiles of the rotationally flattened, circumstellar envelopes observed towards low-mass YSOs at millimeter wavelengths (Koerner & Sargent 1995) and in the near-IR (Cotera et al 2001). If high-mass star formation proceeds as a scaled-up version of the low-mass case, rotationally flattened, thick disks/envelopes could characterize the earliest protostellar phase, when only a minor fraction of the available circumstellar material has been accreted onto the protostar.…”

The Visible and Near‐Infrared Dust Opacity Law in the HH 30 Circumstellar Disk

“…Furthermore, grain growth is probably the first step in the process of planet formation. For this reason, there has been intense interest in finding evidence for grain growth in circumstellar disks, with many observational claims for its discovery (Beckwith et al 1990;Beckwith & Sargent 1991;Mannings & Emerson 1994;Throop et al 2001;Cotera et al 2001;D'Alessio, Calvet, & Hartmann 2001;Calvet et al 2002;Wood et al 2002;Wolf, Padgett, & Stapelfeldt 2003) but also indications that in some disks the dust is not too different from ISM dust (Silber et al 2000;Stapelfeldt et al 2003;Wolf et al 2003).…”

“…If the dust is completely gray in the visible and near-infrared (i.e., the opacity is independent of wavelength), the dark lane thickness should be constant with wavelength; if the dust is chromatic (i.e., the opacity changes with wavelength), the dark lane should appear narrower at wavelengths at which the opacity is lower. Edge-on disks whose dark lanes are known to narrow toward longer wavelengths include Orion 114-426 (McCaughrean et al 1998), IRAS 04302+2247 (Padgett et al 1999), HH 30 (Cotera et al 2001), and HV Tauri C . Similarly, Shuping et al (2003) recently found that the outer radius of the Orion 114-426 silhouette disk decreases toward longer wavelengths.…”

“…In this way, the opacity law over a range of wavelengths can be determined, the dust size distribution function can be constrained, and even small changes in dust properties can be identified. Cotera et al (2001) applied this technique to images of HH 30 at 1.10, 1.60, and 2.04 m, finding that the opacity law between 1 and 2 m was flatter than in the ISM. In contrast, Wolf et al (2003) performed a similar analysis of IRAS 04302+2247, again at 1.10, 1.60, and 2.04 m, but found that the opacity law in this object was very similar to that in the ISM.…”

“…In this paper, we apply this same modeling approach to the HH 30 edge-on disk. Our goal is to simultaneously explore the parameter space of disk density laws and dust properties and thereby determine the robustness of the conclusions about grain growth reached by Cotera et al (2001). In addition, we fit 0.44, 0.81, and 2.04 m images and thereby significantly extend the wavelength leverage.…”