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Description
The primary targets of the NASA Transiting Exoplanet Survey Satellite will be K and M dwarf stars within our solar neighbourhood. Young K and M dwarf stars are known to exhibit a high starspot coverage (~50%), however, older stars are known to show fewer starspots. This implies that TESS 2 min cadence transit light curves may contain starspot anomalies, and if so, will require transit-starspot models to accurately determine the properties of the system. The goals are to determine if starspot anomalies can manifest in TESS transit light curves, to determine the detection limits of the starspot anomalies and to examine the relationship between the change in flux caused by the starspot anomaly and the planetary transit. 20573 simulations of planetary transits around spotted stars were conducted using the transit-starspot model, PRISM. In total 3888 different scenarios were considered using three different host star spectral types, M4V, M1V and K5V. The mean amplitude of the starspot anomaly was measured and compared to the photometric precision of the light curve, to determine if the starspot anomaly's characteristic "blip" was noticeable in the light curve. Results. The simulations show that, starspot anomalies will be observable in TESS 2 min cadence data. The smallest starspot detectable in TESS transit light curves has a radius of ~1900km. The starspot detection limits for the three host stars are: 4900+/-1700km (M4V), 13800+/-6000km (M1V) and 15900+/-6800km (K5V). The smallest change in flux of the starspot ({Delta}F_spot_=0.00015+/-0.00001) can be detected when the ratio between the planetary and stellar radii, k=0.082+/-0.004. The results confirm known dependencies between the amplitude of the starspot anomaly and the photometric parameters of the light curve. The results allowed the characterisation of the relationship between the change in flux of the starspot anomaly and the change in flux of the planetary transit for TESS transit light curves.
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