STScI Logo, Space Telescope Science Institute

John H. Debes

ESA/AURA Astronomer, COS/STIS Instrument Team

An image of G29-38, taken with NICMOS, that shows light from the star (left) and the same light subtracted using ADI. An artificial companion has been inserted 30 AU away that has the equivalent brightness to an object with 5 times the mass of Jupiter.

Exoplanet Detection

In addition to understanding the dynamics of planetary systems around dying stars, I am interested in directly detecting gas giants around white dwarfs--I have conducted several searches for faint companions to WDs using the Canada France Hawaii Telescope, NICMOS, and WFC3 on the Hubble Space Telescope. I have mainly used Angular Differential Imaging(ADI) of WDs to look for faint companions--that is where you image a target star at at least two different telescope orientations. Real objects on the sky rotate, while static features such as speckles and detector artifacts remain in the same position. This allows you to subtract off the large glare (known as the point spread function, or PSF) coming from the bright star in order to search for fainter objects nearby. This high contrast imaging around WDs is quite successful: My observations would have detected objects larger than 5 times the mass of Jupiter.