A Uniform Retrieval Analysis of Ultra-cool Dwarfs. IV. A Statistical Census from 50 Late T-dwarfs

• Other Authors: Saboi, Kezman (Author)
• Format: Dissertation
• Language: English
• Published: 2020
• Subjects: Astrophysics
• Online Access: http://hdl.handle.net/2286/R.I.63047

abstract: The spectra of brown dwarfs are key to exploring the chemistry and physics thattake place in their atmospheres. Late T dwarf (950 - 500 K) spectra are particularly diagnostic due to their relatively cloud free atmospheres and deep molecular bands. With the use of powerful atmospheric retrieval tools, these properties permit constraints on molecular/atomic abundances and temperature profiles. Building upon previous analyses on T and Y dwarfs (Line et al. 2017; Zalesky et al. 2019), I present a uniform retrieval analysis of 50 T dwarfs via their low-resolution near infrared spectra. This analysis more than doubles the sample of T dwarfs with retrieved properties. I present updates on current compositional trends and thermal profile constraints amongst the T dwarf population. My analysis shows that my collection of objects form trends that are consistent with solar grid model expectations for water, ammonia, methane, and potassium. I also establish a consistency between the thermal structures of my objects with those of grid models. Moreover, I explore the origin of gravity-metallicity discrepancies that are observed in some of my brown dwarf candidates. === Dissertation/Thesis === Masters Thesis Astrophysics 2020