Submillimeter Structure of the Disk of the Butterfly Star

TL;DR

This paper provides high-resolution submillimeter observations of the Butterfly star's disk, revealing detailed inner disk structure, optical thickness at 894 microns, and implications for grain growth and planet formation.

Contribution

It offers the first spatially resolved 894 micron map of the disk, revealing inner disk optical thickness and detailed dust properties, improving understanding of young circumstellar disks.

Findings

Inner disk shows a brightness minimum at the center.

Disk is optically thick at 894 micron wavelength.

Provides constraints on dust grain properties in planet-forming regions.

Abstract

We present a spatially resolved 894 micron map of the circumstellar disk of the Butterfly star in Taurus (IRAS 04302+2247), obtained with the Submillimeter Array (SMA). The predicted and observed radial brightness profile agree well in the outer disk region, but differ in the inner region with an outer radius of ~80-120 AU. In particular, we find a local minimum of the radial brightness distribution at the center, which can be explained by an increasing density / optical depth combined with the decreasing vertical extent of the disk towards the center. Our finding indicates that young circumstellar disks can be optically thick at wavelengths as long as 894 micron. While earlier modeling lead to general conclusions about the global disk structure and, most importantly, evidence for grain growth in the disk (Wolf, Padgett, & Stapelfeldt 2003), the presented SMA observations provide more detailed constraints for the disk structure and dust grain properties in the inner, potentially planet-forming region (inside ~80-120 AU) vs. the outer disk region (~120-300 AU).