Hannah Jang-Condell
Carnegie Fellow

Curriculum Vitae
Publications List

Currently a Michelson Fellow at University of Maryland and NASA's Goddard Space Flight Center.
Contact Information:
Department of Astronomy
University of Maryland
College Park, MD 20742
301-405-8360 (UMD)
301-286-7923 (GSFC)
hannah AT astro DOT umd DOT edu

Research Projects:

• Radiative Transfer in Protoplanetary Disks. For my PhD thesis, I calculated radiative transfer on the surface of a protoplanetary disk with an embedded sub-Jupiter mass planet. The gravitational potential of the planet creates shadows and brightenings on the disk's surface, leading to cooling to one side of the planet and heating on the other side. A forming planet can affect its own formation environment by modifying the properties of disk material around it. Temperature perturbations can also slow Type I migration.

• Self-Consistency in Perturbed Disk Structure. Temperature perturbations due to shadowing and illumination effects will affect the density structure of the disk. This creates a positive feedback loop where cooled regions contract and heated regions expand, deepening the shadows and steepening illuminated surfaces. Previous work assumed a plane-parallel approximation for the disk structure, but to accurately model the effect of feedback, the radial and azimuthal variation of the disk must be taken into account. I am exploring theoretical and observable consequences of these planet shadows.

• Observable Signatures of Core Formation. As a planet grows in size from an Earth mass to a Jupiter mass, it begins to affect the disk structure by generating density waves and forming a gap. Illumination of these structures can create large-scale shadows in the disk. In order to identify these potentially observable signatures of core formation in a protoplanetary disk, I am working with Mordecai Mac-Low and Jeff Oishi to implement my radiative transfer modelling in their 3D hydrodynamic simulations of planets in disks.

• Observable Signatures of Gravitational Instability. If planets form by gravitational instability, where the disk fragments into self-gravitating clumps, this process could have observable signatures different from that of core formation. I am working with Alan Boss to model signatures of planet formation via gravitational instability. Whether planets form by gravitational instability or core accretion is a long-standing debate in planet formation theory, and observational evidence for either scenario would be a great advance.

• Full Disk Structure. I am modifying my radiative transfer models to calculate full disks with inner holes, whether they are formed by dust sublimation, photoevaporation, the presence of a planet, or some other disk-clearing mechanism. My objective is to fit disk models to observed SEDs and interferometric observations to better understand the detailed structure of these disks. This could help settle the debate over whether or not puffed-up inner rims at the dust sublimation radius cause disk self-shadowing.

• Dust Modelling. One major limitation of my models is that the dust is calculated very simply: using mean integrated opacities, assuming it is well-mixed with the gas, and equating the dust and gas temperatures. In reality, dust composition, size distribution, and spatial distribution can vary greatly within a disk because of temperature variations, coagulation of particles, and midplane settling. With a proper dust model, I can calculate scattered light images from disks with embedded planets. Synthesizing optical and infrared data into a coherent disk model will help us understand the structure of real disks.

• Astrobiology. I am interested astrobiology, particularly in how the formation environment of a planetary system might favor the formation of a life-harboring planet. What initial conditions favor terrestrial formation in the habitable zone? How does the composition of a protoplanetary disk affect the final composition of a planet? What planetary characteristics are necessary for life, in terms of composition, orbital parameters, and size? How did life arise on Earth and how might that process be duplicated on other worlds?

Links:

• Astronomy and Astrophysics
• DTM