I am a PhD student in the Astronomy and Astrophysics group at the University of Warwick under the supervision of Dr Matteo Brogi.
My research looks into characterising extra-solar (exoplanet) atmospheres using the high-resolution cross-correlation spectroscopy method (HRCCS). By observing atmospheres in incredibly fine detail (R = ~ 100,000), we can resolve the hundreds of absorption lines that are unique to each molecule that may be present in the atmosphere. Since the signal from the planet is so faint, we need to amplify this signal by using a technique called cross-correlation which helps us match the spectrum buried deep in the noise of the data to a well-known template spectrum for each molecule. This ‘fingerprinting’ allows us to unambiguously detect any molecule that may be present within the atmosphere.
Using this method, I have primarily been observing giant planets on very close-in orbits around their host stars, planets that are very unlike anything in our own solar system. These planets are roughly of Jupiters size and mass on orbits that last only a few days, because of this, these planets can reach temperatures of over 1000 degrees celsius! Due to these favourable observing conditions, we can directly trace the orbital motion of these planets over several hours of observation which allows us to accurately determine the orbital parameters and a direct measurement of the mass of the planet. This technique can also measure the rotational and any wind velocities present in the atmosphere.
Since these measurements need to be so sensitive and accurate, we have to use some of the biggest telescopes (e.g. the VLT) with some of the most stable spectrographs (e.g. CARMENES, mounted on the Calar Alto Observatory) in the world to detect the orbital signature from the planet. With these instruments constantly getting upgrades and bigger telescopes coming online, we are working towards using this technique on cooler and smaller (more earth-like) planets.
First author :
- R.K. Webb et al., MNRAS, 2020. "A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L-band"
- Y. Zhang, I.A.G. Snellen, P. Molliere, F.J. Alonso-Floriano, R.K. Webb, M. Brogi, A. Wyttenbach, A&A, 2020. "A search for He l airglow emission from the hot Jupiter Tau Boo b"
- S. Gandhi, M. Brogi, R.K. Webb, MNRAS, 2020. "Seeing above the clouds with high resolution spectroscopy"
- S. Gandhi, M. Brogi, S.N. Yurchenko, J. Tennyson, P.A. Coles, R.K. Webb, et al., MNRAS, 2020. "Molecular cross-sections for high resolution of super-Earths, warm Neptunes, and hot Jupiters"
I am more than happy to be contacted with the possibility of providing talks for outreach purposes! Previous outreach work is listed below:
- Regular volunteer for the Warwick Astronomy mobile planetarium, primarily directed towards younger children.
- Given a talk to the Warwick Astronomy society on exoplanet detection and my research projects.
- Given a talk to a group of A-level students at a local Warwickshire school on exoplanet detection and characterisation.
- Extreme Solar Systems IV, August 2019, Reykjavik Iceland.
- Sagan Summer Workshop, July 2020, Online virtual conference.
- Exoplanets III, July 2020, Online virtual conference.
- STSci Spring Symposium: Towards the Comprehensive Characterization of Exoplanets: Science at the Interface of Multiple Measurement Techniques, April 2021, Online virtual conference.
- ERES (Early Researchers in Exoplanet Science) 2021, May 2021, Online virtual conference.