I was thrilled to learn that Meiji Nguyen‘s AAS poster, which I displayed in an earlier blog post, was awarded a Chambliss medal by the American Astronomical Society. Meiji obtained his undergraduate degree in astronomy from UC Berkeley and is currently working with us as a gap year student.
His poster, “Baade’s Window: An astrometric calibration field for high-contrast imaging of exoplanets,” concerned an essential scientific aspect of all planet discoveries made with the Gemini Planet Imager: astrometry, or the ultra-precise measurement of a planet’s position over time.
Imaging discoveries of exoplanets relies heavily on astrometry — we have to show that as the star moves across the sky the planet follows the same motion, otherwise it is an unrelated object in the foreground or distant background. Once the candidate planet is confirmed through astrometry, we can also measure a more subtle change of position due to orbital motion around the star. The changes of position over time give us the orbital elements of the planet, such as whether or not it has a circular orbit or a highly elliptical orbit. The characteristics of the orbit then give us important information about how the planet formed and evolved, and could even reveal the existence of other planets nearby that have yet to be discovered.
However, telescope optics and other effects can distort the measurements of position. That’s why we need a standard field of stars with well-known positions, sort of like obtaining graph paper with straight lines that offers a fixed grid for plotting points. Our field of stars is called “Baade’s Window” after the astronomer Walter Baade who studied this region.
Thus, when we announce the properties of distant, directly imaged exoplanets such as 51 Eri b and beta Pic b, we rely on Meiji’s measurements of stellar positions in Baade’s Window. Congratulations again to Meiji for his outstanding work!