Debris Disks in the AB Doradus Moving Group (Abstract)

Volume 38 number 1 (2010)

Mimi Hang

Abstract

(Abstract only) The field of planetary science is quickly developing due to our appetite to learn more about the formation of our solar system and about planets around other stars. After the Jovian planets formed in our own solar system, it is believed that our solar system underwent a period of high dust production. For example, our terrestrial planets are thought to have formed from collisions between planetary embryos which includes the large collision that formed our moon when our solar system was ~50 Myr. These collisions formed more dust which swirled around our sun to become a debris disk. We can apply the model here to other star systems. Collisions between planetary embryos of other star systems must also produce high dust production and the dust grains are warmed by stellar light. These dust grains emit thermal infrared radiation which can be detected using space-based infrared telescopes such as the Spitzer Space Telescope (SST). However, it is important to note that the majority of these debris disks are not spatially resolved with current telescopes. The goal of this project was to figure out if there were any debris disks around the stars in the AB Dor moving group. In this project, the moving group AB Doradus was chosen because at 50 Myr and only 20 pc away from Earth, the stars in this association make for an extraordinary laboratory for inquiry of the end-stages of planetary formation. Data was obtained from the Spitzer Space Telescope’s FEPS Legacy MIPS observations. The approach was to: 1) reduce Spitzer data to measure the brightness of the stars at 24 and 70 microns, 2) estimate the brightness of the stellar photosphere at those wavelengths and finally, 3) to look for an excess in the infrared emission which would indicate thermal radiation from dust grains. The study revealed that about 21% of the stars measured in AB Dor have debris disks. However, only the star system of HIP 18859 had an excess at both 24 and 70 microns. Therefore, only HIP 18859 is guaranteed to have a debris disk based on the result of this study.