J/A+A/672/A144 PLATO simulated light curves (Canocchi+, 2023)
Discovering planets with PLATO:
Comparison of algorithms for stellar activity filtering.
Canocchi G., Malavolta L., Pagano I., Barragan O., Piotto G., Aigrain S.,
Desidera S., Grziwa S., Cabrera J., Rauer H.
<Astron. Astrophys. 672, A144 (2023)>
=2023A&A...672A.144C 2023A&A...672A.144C (SIMBAD/NED BibCode)
ADC_Keywords: Models
Keywords: planets and satellites: detection - techniques: photometric -
methods: data analysis - stars: activity - planetary systems
Abstract:
To date, stellar activity is one of the main limitations in detecting
small exoplanets via the transit photometry technique. Since this
activity is enhanced in young stars, traditional filtering algorithms
may severely under-perform in detecting such exoplanets, with shallow
transits often obscured by the photometric modulation of the light
curve.
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 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 the Wotan package, namely the Tukey's
biweight and the Huber Spline algorithms.
For this purpose, 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, have been performed.
These experiments were carried out over a set of 100 realistically
simulated light curves of both quiet and active solar-like stars
(i.e., F and G-type) that will be observed by the ESA space telescope
PLATO (PLAnetary Transits and Oscillations of stars), to be launched
in 2026.
From the experiments for transit detection, it was found that N&L is
the best choice in many cases, since it misses the lowest number of
transits. However, this algorithm 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 works better. Moreover for light curves with a large number
of data-points, the combined results of two algorithms, YSD and Huber
Spline, yield the highest recovery percentage. Filtering algorithms
allow us to obtain 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 then compulsory for a proper
planetary characterization.
Description:
There are 200 cds files called "LC_0*.dat". They are PLATO simulated
light curves of quiet and active solar-like stars, respectively, as
described in Sect. 2 of the paper. Produced with PSLS 1.2 by the Light
curve Stitching Working Group,they are binned at 600 sec, spanning a
temporal range of 2 years, divided into 8 quarters of about 88 days
each.
In each file there are three columns: time (in days), normalized flux
and quarter number.
Moreover, the files tableb1.dat and tableb2.dat describe the input
parameters for the simulated light curves.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 90 100 Input parameters for the 100 simulated PLATO
light curves of the quiet sample
tableb2.dat 91 100 Input parameters for the 100 simulated PLATO
light curves of the active sample
lc/* . 200 Individual PLATO simulated light curves
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- LC Light curve number
4- 6 I3 --- ID Stellar ID in Aigrain et al.
(2015MNRAS.450.3211A 2015MNRAS.450.3211A)
8- 11 F4.2 Sun A Activity level relative to the solar
13- 17 F5.2 d Prot Stellar rotational period
19- 26 F8.3 K Teff Effective temperature
28- 33 F6.4 [cm/s2] logg Surface gravity
35- 41 F7.4 --- [Fe/H] Metallicity ([Fe/H])
43- 51 F9.7 g/cm3 rho Stellar density
53- 61 F9.7 --- u1 Limb darkening coefficient
63- 72 F10.7 --- u2 Limb darkening coefficient
75- 91 A17 --- FileName Name of the light curve file
in subdirectory lc
--------------------------------------------------------------------------------
Byte-by-byte Description of file: lc/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 F20.16 d Time [0.0/703.26] Observational time
22- 39 F18.16 --- Flux [0.9/1.01] Normalized stellar flux
41- 58 F18.16 --- Quarter [1.0/8.0] PLATO quarter number
--------------------------------------------------------------------------------
Acknowledgements:
Gloria Canocchi, gloria.canocchi(at)astro.su.se
References:
Aigrain et al., 2015MNRAS.450.3211A 2015MNRAS.450.3211A
(End) Patricia Vannier [CDS] 21-Feb-2023