I am using Python package lightkurve for exoplanets searching by the transit method. When I download light curve of some star and apply periodogram, I find frequency and power of periodic components in the light curve. However, I noticed that multiples (0.5x, 2x, ...) of the original period are displayed too. Here is example for Kepler-6b.
import lightkurve as lk
import numpy as np
light_curve = lk.search_lightcurvefile("Kepler-6", quarter=1).download().PDCSAP_FLUX
light_curve.scatter()
periodogram = light_curve.to_periodogram(method="bls", period=np.arange(0.5, 10, 0.0001))
periodogram.plot()
I could take only strongest period (3.24 d), but what if there are more exoplanets (1.08 d, 9.71 d, ...)? I thought that if I use the light_curve.fold(period)
method, I can tell if it is a transit (there is only drop of flux) or not (there are more drops of flux). However, Kepler-20f has also multiple drops of flux after fold light curve (because of other planets?).
How can I tell if it is a planet transit or not?