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John H. Debes

ESA/AURA Astronomer, COS/STIS Instrument Team

Scattered Light Images of Young Circumstellar Disks

In addition to very old stars, I study the youngest stars in the galaxy to understand the initial conditions of planet formation. Currently, I am a Co-I on a large STIS program on HST that is imaging debris disks at unprecedented levels of detail, searching for evidence of planetary systems. By looking at disks in scattered light, you can determine new information about the composition of dust in these disks, which gives a remote measure of what the planets in these disks are made of.

The work I am best known for previously has dealt with the color and environment of debris disks. I have constructed one of the best measures of scattered light in a debris disk as a function of wavelength for the disk around HR 4796A. The very red color in this disk might be due to the presence of complex organic molecules. Additionally, I have modeled for the first time the affect of debris disks moving through dense ISM clouds. It is starting to look like a lot of debris disks may be affected by interactions with the ISM, but the exact nature of this interaction is still a mystery!

Below are a sample of images from different work I have done:

This is a false color image of HR 4796A composed of visible and near-IR light (blue=STIS, green=1.71 micron, red=2.22 micron). It's red color is caused by dust grains that scatter light poorly in the visible and very efficiently in the near-IR.

This images shows the debris disk around HD 61005, and a model of debris disk dust grains being blown by and interstellar wind. This work was a Goddard web feature (look there for a cool movie showing one of the models). There's also an interview with me about this subject by the Goddard blog, blueshift