Master Thesis defense by Sanne Hardis – Niels Bohr Institute - University of Copenhagen

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Master Thesis defense by Sanne Hardis

Title: The Transiting Exoplanet GJ 1214b


The first exoplanets were detected and confirmed less than 20 years ago, and since then the field of exoplanet studies has been rapidly developing. More than a thousand exoplanets have been discovered, varying in sizes, masses and orbital distances to their parent star, many of these not similar to what we knew from our own Solar system, and we are still learning on subjects such as planet formation, and the distribution of the exoplanet population. The search is still on for a planet in similar size and mass to the Earth, lying wihtin the so-called habitable zone, were it would be possible for an Earth-like planet to sustain liquid water on the surface. It might not be long, though, as observation from the Kepler space mission recently revealed the first planets of a size simliar to and smaller than the Earth, though these were not located within the habitable zone.

I will present my study of the transiting exoplanet GJ 1214b, based on photometric observations from the Danish 1.54-meter telescope at the ESO La Silla observatory in Chile, carried out in 2010 and 2011. It was the second transiting super-Earth to be detected, and the first offering good opportunities for follow-up studies of the atmosphere it contains, and placed in a mass and radius range where there exist a degeneracy on the composition, it has been and still is a planet of interest regarding further studies.

Transit observations make it possible to derive orbital parameters of the system, and combined with radial velocity studies, estimates of the planetary radius and mass can be made. I have analysed observations of transits obtained with two different methods: Defocused photometry for high-precision milli-magnitude photometry, and lucky imaging, which has not been tested for transit light curve photometry before, but is hoped to be useful for achieving an improvement in accuracy of the transit timing, where possible variations can be related to further planets or exomoons in the system. While the defocused observations in this project yielded good light curves, the lucky imaging observations obtained were not found to be suitable for differential photometry, though, with a different target star, the method might still prove to work for precision timing measurements of exoplanetary transits, obtained from a ground-based telescope.

Supervisor: Uffe Gråe Jørgensen,  Niels Bohr Institute