Herschel-PACS observation of the 10 Myr old T Tauri disk TW Hya: Constraining the disk gas mass

TL;DR

This study uses Herschel-PACS observations and modeling to constrain the gas and dust mass in the 10 Myr old TW Hya protoplanetary disk, providing insights into disk composition and evolution.

Contribution

It presents the first combined observational and modeling approach to estimate the gas and dust masses in TW Hya's disk, highlighting a potentially lower gas-to-dust ratio than interstellar standards.

Findings

Detected [OI] 63 micron line in TW Hya disk

Estimated dust mass of ~1.9 x 10^-4 Msun for grains < 1 mm

Derived gas mass between 0.5 and 5 x 10^-3 Msun

Abstract

Planets are formed in disks around young stars. With an age of ~10 Myr, TW Hya is one of the nearest T Tauri stars that is still surrounded by a relatively massive disk. In addition a large number of molecules has been found in the TW Hya disk, making TW Hya the perfect test case in a large survey of disks with Herschel-PACS to directly study their gaseous component. We aim to constrain the gas and dust mass of the circumstellar disk around TW Hya. We observed the fine-structure lines of [OI] and [CII] as part of the Open-time large program GASPS. We complement this with continuum data and ground-based 12CO 3-2 and 13CO 3-2 observations. We simultaneously model the continuum and the line fluxes with the 3D Monte-Carlo code MCFOST and the thermo-chemical code ProDiMo to derive the gas and dust masses. We detect the [OI] line at 63 micron. The other lines that were observed, [OI] at 145 micron and [CII] at 157 micron, are not detected. No extended emission has been found. Preliminary modeling of the photometric and line data assuming [12CO]/[13CO]=69 suggests a dust mass for grains with radius < 1 mm of ~1.9 times 10^-4 Msun (total solid mass of 3 times 10^-3 Msun) and a gas mass of (0.5--5) times 10^-3 Msun. The gas-to-dust mass may be lower than the standard interstellar value of 100.