George Eliot Academy students and Orbyts Fellows Marina Lafarga Magro and Yoshi N. E. Eschen from the University of Warwick conducted a research project to analyse two exoplanetary systems, KELT-20 and TOI-431, for transit timing variations (TTVs). Exoplanets are planets found outside our solar system, and they can be detected through photometry when a planet transits in front of its host star.

The timing of these transits can sometimes vary, appearing either earlier or later than expected, known as a TTV. These TTVs can be caused by the gravitational influence of other planets in the system or by a planet's slow orbital decay. To investigate these phenomena, the team utilized data from two space telescopes, TESS (Transiting Exoplanet Survey Satellite) and CHEOPS. The students used a Python library called pycheops to detrend the CHEOPS data and another called juliet to fit the transit.

The analysis of KELT-20, a system with a single known planet, revealed minor offsets in the transit times. The researchers found that the differences between the measured and expected transit times were all under 2 minutes. They noted that these small offsets could be attributed to uncertainties in their detrending and analysis methods, as no clear trend was visible. In contrast, their analysis of TOI-431, a system known to contain three planets, showed more significant TTVs. The team observed transit time offsets of up to 10 minutes.

By comparing the CHEOPS transit times to the TESS fits, the researchers found small differences in transit times for both KELT-20 b and TOI-431 b. The larger offsets observed in the TOI-431 system are particularly noteworthy, as they could be caused by the gravitational influence of the system's two other known planets. These findings highlight the importance of high-precision observations in understanding the complex dynamics of exoplanetary systems!