Millimeter Observations of the Transition Disk around HD135344B (SAO 206462)

TL;DR

This study uses millimeter observations to reveal a cavity in the dust and gas of the HD 135344B transition disk, supporting planet formation as the clearing mechanism and indicating overall CO depletion.

Contribution

First high-resolution millimeter imaging of HD 135344B's disk showing combined dust and gas cavity evidence, suggesting planet formation as the clearing process.

Findings

Inner disk cavity in dust and gas confirmed

Evidence supports planet formation over photoevaporation

Global CO depletion observed in the disk

Abstract

We present \sim1" resolution 1.3 millimeter dust continuum and spectral line (12CO and 13CO J=2-1) observations of the transitional disk system HD 135344B obtained with the Submillimeter Array. The disk shows a Keplerian rotation pattern with an inclination of \sim11{\deg}, based on the spatially and spectrally resolved 12CO and 13CO emission. The data show clear evidence for both dust and gas surface density reductions in the inner region of the disk (radius \lesssim 50 AU) from the continuum and 13CO J=2-1 data, respectively. The presence of this inner cavity in both the dust and gas is more consistent with clearing by giant planet formation than by photoevaporation or by grain growth. There is also an indication of global CO gas depletion in the disk, as the mass estimated from 13CO emission (\sim3.8 \times 10^(-4) M\odot) is about two orders of magnitude lower than that derived from the 1.3 mm continuum (\sim2.8 \times 10^(-2) M\odot).