2 research outputs found
Discovering planets with PLATO: Comparison of algorithms for stellar activity filtering
Context. To date, stellar activity is one of the main limitations in
detecting small exoplanets via transit photometry. Since this activity is
enhanced in young stars, traditional filtering algorithms may severely
under-perform in detecting such exoplanets.
Aims.This paper aims to compare the relative performances of four algorithms
developed by independent research groups specifically for the filtering of
activity in the light curves (LCs) of young active stars, prior to the search
for planetary transit signals: Notch and LOCoR(N&L), Young Stars
Detrending(YSD), K2 Systematics Correction(K2SC) and VARLET. We include in the
comparison also the two best-performing algorithms implemented in Wotan, namely
the Tukey's biweight and the Huber Spline.
Methods. We performed a series of injection-retrieval tests of planetary
transits of different types, from Jupiter down to Earth-sized planets, moving
both on circular and eccentric orbits. The tests were carried out over 100
simulated LCs of both quiet and active solar-like stars that will be observed
by the ESA space telescope PLATO.
Results. We found that N&L is the best choice in many cases, since it misses
the lowest number of transits. However, it under-performs if the planetary
orbital period closely matches the stellar rotation period, especially in the
case of small planets for which the biweight and VARLET algorithms work better.
For LCs with a large number of data, the combined results of YSD and Huber
Spline yield the highest recovery percentage. Filtering algorithms allow us to
get a very precise estimate of the orbital period and the mid-transit time of
the detected planets, while the planet-to-star radius is under-estimated most
of the time, especially in the case of grazing transits or eccentric orbits. A
refined filtering taking into account the presence of the planet is compulsory
for a proper planetary characterization.Comment: 25 pages, accepted for publication by A&