I am a Lecturer in Astrophysics at Queen's University Belfast (i.e. an Assistant Professor in US/EU nomenclature). Previously I worked as a Sagan Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics, where I continue to be an external Research Associate. I am interested in how exoplanets form, how they develop over time, and how all of this is influenced by the high-energy radiation that is produced by the host stars of these exoplanets. I work a lot with space telescopes to perform observations in X-rays and in the ultraviolet; I also use ground-based telescopes to collect high-resolution spectra.
Transits of exoplanets in front of their host stars are our prime tool to investigate the composition of exoplanetary atmospheres. The transit depths at different wavelengths give us clues about atomic species and densities at different altitudes in the atmosphere. I am working on data at short wavelengths (X-ray and UV) to investigate the outermost layers of exoplanet atmospheres. Because many exoplanets evaporate over time, these outer layers are particularly important to understand their evolution.
Stars with an outer convective zone like the Sun produce strong, highly structured magnetic fields through a magnetic dynamo process. These magnetic fields cause star spots, flares, coronal mass ejections, and are the cause for the hot outer layers of stars, the chromosphere and corona. To understand the heating processes and sudden energy release by magnetic flares, we use X-ray observations of stellar coronae. These processes can also have a strong influence on planets in close orbits around their host stars, because high-energy irradiation is the main driver for atmospheric evaporation.
Planets form in the disks surrounding young stellar objects. The inner parts of such disks are not accessible to spatially resolved observations yet, we can however study the processes of the inner disk using near- and mid-infrared observations. At those wavelengths, changes in the disk are what dominates the brightness variations of the star-disk system. I am part of the YSOVAR project to study young stellar objects, planet formation, and accretion with data from the Spitzer space telescope.
Planets around other stars often experience very different space weather conditions than our rather tepid Earth. Especially in systems where the host star is a red dwarf and the habitable zone is close to the star, the magnetic activity of the star can influence the chances for life to develop. We have shown that in such systems the atmosphere of habitable-zone planets may get completely stripped away (Cohen et al. 2014).
I have taught lecture courses on Astronomy and Exoplanet Science at different institutes. At Queen's, I will be teaching the following course:
After the class has begun, I will post the weekly assignments and additional information on this course website: PHY1003.
YSOVAR is an Exploration Science program conducted by the Spitzer Space Telescope. The YSOVAR project has performed extensive mid-infrared monitoring of 12 star-froming regions to hunt for clues to accretion disk physics and protostar rotational evolution. The YSOVAR collaboration is led by John Stauffer and Luisa Rebull. I am part of the scientific analysis team, which includes astronomers from several institutions such as Caltech, CfA, and Lowell Observatory.
I am part of the proposal team for Arcus, a high-resolution X-ray spectrometer onboard the International Space Station. Arcus has the capability to make significant progress in studying exoplanets and their host stars, young stellar objects, supermassive black holes, and gas and dust in the Milky Way.
Athena, the Advanced Telescope for High Energy Astrophysics, is ESA's new large-class space telescope. Its launch is currently planned for 2028. Athena will investigate a wide range of topics including galaxy clusters, supermassive black holes, supernovae, acrretion processes, star formation, and exoplanets. I am a member of Athena's Science Working Group 3.1 on Solar System and Exoplanets.
Transit timing variations (TTVs) provide a possibility to constrain the masses of exoplanet candidates. KOINet will follow-up on TTVs of transiting objects discovered with the Kepler space telescope, using a worldwide network of ground-based telescopes. KOINet is managed by the international KOINet Board, with the project lead being located in Goettingen, Germany; I am one of the five Board members.
I am a member of the Athena SWAN Team of Queen's School of Mathematics and Physics. In January 2016, I ran a workshop on Unconscious Bias Awareness on behalf of the Athena SWAN Team and Chris Watson (who is the Athena SWAN champion at the School of Mathematics and Physics). The slides, peer-reviewed publications, and further materials are listed on this page: UnconsciousBias.