1 Searching for TOI 1798 candidates
TOI-1798 is a star with R=0.78R_sun with two candidate official TOI alerts (https://exofop.ipac.caltech.edu/tess/target.php?id=toi1798). We are interested in assessing these signals and finding additional ones. Hence, we will run the sherlock search for this potential multi-planetary system, run the vetting procedure for all the signals and will try to validate them.
We will use the properties file named search.yaml under the same directory than this notebook.
import os
your_execution_dir = os.getcwd()
with open(your_execution_dir + '/search.yaml', 'r') as f:
print(f.read())
TARGETS:
'TIC 198153540': #TIC number
SECTORS: [16, 22, 23, 49, 50]
INITIAL_SMOOTH_ENABLED: True
INITIAL_HIGH_RMS_MASK: True
INITIAL_HIGH_RMS_THRESHOLD: 1.5
DETREND_METHOD: 'biweight'
DETRENDS_NUMBER: 12
DETREND_CORES: 7
MAX_RUNS: 4
SNR_MIN: 6
SDE_MIN: 7
CPU_CORES: 7
OVERSAMPLING: 3
PERIOD_MAX: 20
Search execution
We would now have to run sherlock by running it with a python one-liner. Please take into account that this search takes a lot of computational power and time. Hence, we will run this command in a server and will prompt the output in the notebook instead of executing it here:
python3.8 -m sherlockpipe --properties search.yaml
The execution will create a resulting directory named /TIC198153540_[16, 22, 23, 49, 50]. Ok, let’s inspect the candidates found by sherlock:
with open(your_execution_dir + '/TIC198153540_[16,_22,_23,_49,_50]/TIC198153540_[16, 22, 23, 49, 50]_candidates.log', 'r') as f:
print(f.read())
Listing most promising candidates for ID TIC198153540_[16, 22, 23, 49, 50]:
Detrend no. Period Per_err Duration T0 Depth SNR SDE FAP Border_score Matching OI Harmonic Planet radius (R_Earth) Rp/Rs Semi-major axis Habitability Zone
11 8.0217 0.00087 101.82 1741.59 0.867 35.52 56.19 0.000080 1.00 TOI 1798.01 - 2.52338 0.02685 0.07512 I
1 0.8756 0.00005 51.16 1739.51 0.250 22.41 52.78 0.000080 0.99 nan - 1.35574 0.01357 0.01716 I
1 0.8756 0.00005 50.76 1739.07 0.271 24.38 193.31 0.000080 0.98 nan 1*SOI2 1.41017 0.01372 0.01716 I
8 19.1234 0.00111 133.84 1747.01 0.415 13.36 351.01 0.000080 0.83 nan - 1.74641 0.02084 0.13406 I
It seems that sherlock has spotted the TOI-1798.01 but did not find TOI-1798.02. The latest should have a period of 0.44 days aproximately, which is the half of the found signals in both the second and third runs. That means that sherlock spotted TOI-1798.02 in two different runs. This happened because the default minimum period for sherlock searches is 0.5 days and we didn’t change it.
In addition, a latest signal has been found at 19.12 days in the fourth run. We can take a look:
file_image = your_execution_dir + '/TIC198153540_[16,_22,_23,_49,_50]/4/Run_4_ws=1.7268_TIC198153540_[16, 22, 23, 49, 50].png'
from IPython.display import Image
Image(filename=file_image)
If we looked into the resulting directory, we’d appreciate from the 4th run log that the 19.12 days signal was spotted only in four detrends out of ten and the rest of them found no signals at all:
________________________________ run 4________________________________
=================================
SEARCH OF SIGNALS - Run 4
=================================
win_size Period Per_err N.Tran Mean Depth (ppt) T. dur (min) T0 SNR SDE FAP Border_score Matching OI Harmonic Planet radius (R_Earth) Rp/Rs Semi-major axis Habitability Zone
PDCSAP_FLUX nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
0.4011 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
0.5904 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
0.7798 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
0.9692 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
1.1586 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
1.3480 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
1.5374 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
1.7268 19.12339 0.001110 6 0.415 133.8 1747.0102 13.356 351.011 8.0032e-05 0.83 nan - 1.74641 0.02084 0.13406 I
1.9161 19.12339 0.001110 6 0.412 133.8 1747.0102 13.287 285.781 8.0032e-05 0.83 nan - 1.73820 0.02083 0.13406 I
2.1055 19.12339 0.001110 6 0.405 133.8 1747.0102 13.097 350.962 8.0032e-05 0.83 nan - 1.72525 0.02069 0.13406 I
2.2949 19.12339 0.001110 6 0.401 133.8 1747.0102 12.931 351.011 8.0032e-05 0.83 nan - 1.71523 0.02056 0.13406 I
2.4843 nan -9.749788 nan nan nan 0.0000 nan 0.000 nan 0.00 nan - nan nan nan -
Elected signal with QUORUM algorithm from 4 VOTES --> NAME: 7 Period:19.123394593311595 CORR_SDE: 373.51212301944247 SNR: 13.356395837142067 SDE: 351.0113927170664 FAP: 8.0032e-05 BORDER_SCORE: 0.8333333333333334
This case is a limit scenario and we always are hesitant about this kind of candidates, but we will keep it as an interesting signature and will try to solve it in a vetting execution.