Characterising Ultracool Dwarfs in the Gaia Mission All Sky Survey

Abstract

I present here the characterisation of ultracool dwarfs having been observed through direct, ground-based campaigns. These ultracool dwarfs have been used to assist with the parameterisation of objects as observed by Gaia. I also present software packages and further technical skills, developed for the astronomical community. Data observed from 2015–2016 on the OSIRIS instrument at the GTC was used to measure spectral types and radial velocities for 46 objects. This data was analysed further to ascertain if any objects had interesting features such as young moving group membership or low metallicity features. I led multiple observing proposals and observed on several nights, which resulted in a number of interesting objects being discovered. Expanding on what was known of ultracool dwarfs from direct campaigns, I helped data process the ultracool dwarfs in Gaia data releases. I contributed to ‘downstream’ analysis of these Gaia ultracool dwarfs. This, in turn, enhanced the body-of-knowledge of directly observed ultracool dwarfs. Using Gaia DR3, I created a novel colour ratio to select outliers from Gaia RP spectra. This was a proof-of-concept work to demonstrate that one can use a large, homogeneous population like Gaia, to identify the most extreme outliers from low resolution data. I created multiple software tools and databases, which the community has used to observe, access, analyse and present data.