Hubble reveals complex multi-scale structure in the edge-on protoplanetary disk IRAS 23077+6707

TL;DR

IRAS 23077+6707 is a rare, spectacular edge-on protoplanetary disk whose large angular extent (~14″) and near-edge-on inclination (~80°) make it an excellent laboratory for studying vertical disk structure. The authors present the first sub-arcsecond optical and near-IR HST/WFC3 imaging across six filters from 0.4 to 1.6 μm, revealing a complex morphology including northern filaments, wispy features above the midplane, and a central dark lane, with compact millimeter emission indicating a dense midplane. Radiative transfer simulations show current data cannot decisively distinguish between dust settling and no-settling scenarios, but highlight the need for resolved mid-IR observations to probe the outer atmosphere and dynamical processes. Overall, IRAS 23077+6707 provides a valuable venue to study vertical structure, asymmetries, and evolution in protoplanetary disks, informing models of dust-gas coupling and disk dynamics.

Abstract

We present high-resolution ($\lesssim 0.1''$) Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) imaging of the near edge-on ($i{\sim}80^\circ$) protoplanetary disk IRAS 23077+6707 ("Dracula's Chivito") obtained across six broadband filters spanning $0.4-1.6\,μ$m. These observations unveil the scattered light from this unusually large disk (${\sim}14''$, or ${\sim}4200\,\mathrm{au}$ at $300\,\mathrm{pc}$) in remarkable detail, revealing a rich tapestry of substructures, including brightness asymmetries and signatures of dynamical activity. Extended filaments are detected extending ${\sim}10''$ from the northern edges of both nebulae, while no comparable southern features are observed. In addition to large-scale asymmetries, the disk exhibits prominent wispy features that extend well above the midplane and are visible in all filters, suggesting a complex, possibly turbulent outer disk atmosphere shaped by infall, dynamical stirring, or gravitational instability. The central dark lane narrows from optical to near-IR wavelengths, and high-resolution millimeter data reveal compact midplane emission. Although our radiative transfer simulations show that the current data cannot yet distinguish between dust settling and no-settling scenarios, they underscore the need for resolved mid-infrared observations of this unique system. IRAS 23077+6707 thus represents a rare and valuable laboratory for studying the vertical structure, asymmetries, and evolutionary state of protoplanetary disks.

Figures (1)

• Figure 1: Three-color composite of IRAS23077 using the HST/WFC3 filters F160W (red), F814W (green), and F438W (blue). A $5"$ scale bar is shown in the lower right, which at a distance of $300\,\mathrm{pc}$ (see §\ref{['sec:results']}) corresponds to $1500\,\mathrm{au}$. North is up, east is left.