Osborne, Hannah Laura May; (2025) Understanding exoplanets with radial velocity observations. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text Hannah_Osborne_Thesis.pdf - Accepted Version Download (11MB) | Preview

Abstract

For the past 30 years the field of exoplanet science has grown rapidly; from the first detection of a planet around a main sequence star in 1995 to now over 5800 confirmed detections. One particularly interesting finding from these many discoveries is that our own Solar system does not seem to be the blueprint of all planetary systems; rather the diversity in exoplanets observed so far have challenged most planet formation models. While many efforts remain to try and detect planets in different regions of parameter space, much of the focus has now shifted to characterizing planets in more detail. One way that we try to understand planets is by categorizing them based on their compositions. Whilst planet radii are now fairly-routinely found from transit observations, we still lack mass measurements for many planets. Finding the masses of exoplanets in specific regions of parameter space can help to inform our models of planet formation and evolution. The planet masses which we do have are primarily from radial velocity (RV) observations. But even where we have these follow-up RV observations there remain many open questions about the best ways to model these data and how we can use it to learn about the demographics of exoplanet populations. In this thesis I focus on using RV observations to understand exoplanets. In Chapter 3 I use new observations to characterise a new planet, TOI-544 b, and confirm the discovery of a second planet in the same system. TOI-544 b has an unusual composition, a possible water-world, and is a top candidate for future atmospheric studies. In Chapter 4 I use archival data of a sample of known small planets to test how modelling choices impact the planet masses we find. For each planet I complete a homogeneous analysis with a variety of modelling choices, from this I find that just one change in model choice can impact planet mass up to a factor of 4 even for identical data sets. In Chapter 5 I use these new homogeneously-derived planet masses to show that the inferred compositions are consistent with predictions and propose the top candidates for future study. And finally, in Chapter 6 I use my own RV observations to search for previously-unknown planets which could be causing the migration of gas giants into unusual orbits, finding that some of my sample have potential companions.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as XMLCSVJSON

Archive Staff Only

View Item