Master's Thesis by Steffen Kjær Jacobsen – Niels Bohr Institute - University of Copenhagen

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Master's Thesis by Steffen Kjær Jacobsen

Title: The Dust and Gas Structure of TW Hydrae

The protostar TW Hydrae has long been under scrutiny by astronomers, due to its proximity at only ~ 51 pc and fortuitous face-on alignment relative to Earth, which allows us to see the full protoplanetary disk around the protostar. The large amounts of SED data and interferometry observations have resulted in a plethora of conflicting models of the disk dust and gas structure.
In this thesis I analyze the previous models of TW Hydrae, construct a hybrid dust model from previous work, as well as modeling a simple HCO+ gas distribution of this protoplanetary disk based on the inferred dust temperature from my hybrid dust model.

I find that the dust population is decoupled into at least two size groups where the larger dust grains are truncated at ~ 60 AU while a population of small dust grains are coupled to the HCO+ gas, expanding out to at least 200 AU. I also demonstrate that the two main conflicting models of the inner dust structure can be combined into a hybrid model, with an inner disk at ~ 0.055 AU to 1.05 AU and a dust evacuated gap out to 4 AU where the outer disk begins. Potential causes of the inferred dust gaps and the 60 AU large dust truncation, such as protoplanets, are discussed.

Supervisor: Jes K. Jørgensen