the First planet in the universe
Planet formation needs raw materials - metals, i.e., elements other than H and He. Metals take time to build since the onset of the first star (see the following models by James Johnson). The two dashed lines roughly mark the time when the first rocky planet and gas-giant planet formed when the metallicity is high enough.
I studied how metallicity affects planet formation and found that more metal-rich stars tend to have more planets. With my graduate students, we are searching for the most metal-poor planet systems and investigating how metallicity affects their formation and habitability.
To search for planets around the most metal-poor stars, we need to select a sample metal-poor stars. This is the work of my undergraduate student Jared Kolecki, who selected ~17,000 halo stars that are dynamically hot and metal-poor. His work has been published on the Astronomical Journal.
My graduate student Kiersten Boley, who is also an NSF graduate fellow, is working on the planet search and has finished the first step: searching for hot Jupiters around metal-poor stars. Her work is now published on the Astronomical Journal. Despite non-detections, she put the most stringent upper limit for the occurrence rate of hot Jupiters around halo stars. Next, she will work on searching for smaller planets and understanding planet occurrence as a function of metallicity and in the context of galactic formation.
