Exoplanet detection and characterisation

Since the first discovery of a planet orbiting a star other than our Sun (an “exoplanet”) in 1995, many thousands of exoplanets are now known to orbit stars in our Galaxy.

From their initial discovery we are now in the age of characterising exoplanets using both ground and space based instrumentation. One of the main challenges is seeing the signal from the exoplanet against the glare from its parent star. To do this we combine several techniques, such as polarimetry, adaptive optics and coronagraphs, to see the exoplanet and begin to characterise their atmospheres.

One recent success in the search for directly imaged exoplanets is the Young Suns Exoplanet Survey (YSES), which is a survey for directly imaged exoplanets using the VLT instrument SPHERE, consisting of sample of 70 young stars (around 14 to 17 Myr old) from the Sco-Cen association that were first identified by Eric Mamajek and Mark Pecaut.

The survey has detected two extrasolar planet systems around stars similar in mass to the Sun. The first star has two exoplanets orbiting around it, YSES1b and YSES1c, and a second exoplanet was detected with a mass of 6 Jupiters orbiting about 113 astronomical units from its parent star. Characterising these systems and understanding how these massive planets ended up so far away from where they formed is one of the next challenges being faced.

This animation (above) shows the two planets at different wavelengths. As you go to longer wavelengths, the stars become fainter and the planets become brighter, showing that their effective temperature is much cooler than the stars in the field of view.

Our people exploring exoplanets:

Dr. Matthew Kenworthy

Elina Kleisioti, MSc