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Searching for giant rings around exoplanets

Searching for giant rings around exoplanets


Project description and background

All of the gas giant planets in our solar system have rings around them, with Saturn being the most famous. Although we’ve discovered over 5000 planets over the past two decades, unambiguous signatures of rings around exoplanets (exorings) have not been found. There are currently multiple candidates, for example the young star J1407b showed a dimming event of 95%, which lasted ~50 days, which corresponds to a giant occulting body with a diameter of ~1AU. What is more, it showed structure that is consistent with the edges of rings crossing the star, and may be detecting a circumplanetary disk where moons are forming. However, no repeat transit has occurred, making it unclear if it was a chance alignment with some other astrophysical object.

Since the discovery of J1407b, there have been several other candidates found. These have typically not been discovered from systematic searches, but were detected serendipitously in wide-field surveys such as ASSASN and ATLAS. They now have a large database with a long time-baseline of photometry for large numbers of stars, ideal for a systematic search for the transits of giant rings.

On a smaller scale, the transit of HIP41378 f is anomalously deep compared to its mass, resulting in an extremely low density of ~0.09 g cm-3, which could be indicative of rings surrounding this 10-Earth mass planet.  However, there is no clear evidence of any substructure, which would provide the strongest evidence of rings, and nor are there many other candidates for this sample, although large surveys like TESS and, in the future, PLATO should reveal them.

This project

Applications are invited for a PhD position at Queen's University Belfast (QUB) to work under the supervision of Dr. Ernst de Mooij to search for exoring candidates in the archives of large surveys, and perform detailed characterisation of these and already known candidates. This project will be in collaboration with Dr. Matt Kenworthy (Leiden Observatory).

More information

Supervisor: Dr. Ernst de Mooij (