J/A+A/678/A2 YARARA V2. 4 high proper motion stars RVs (Cretignier+, 2023)
YARARA V2: Reaching sub-m.s-1 precision over a decade using PCA on
line-by-line radial velocities.
Cretignier M., Dumusque X., Aigrain S., Pepe F.
<Astron. Astrophys. 678, A2 (2023)>
=2023A&A...678A...2C 2023A&A...678A...2C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, standard ; Radial velocities ; Optical
Keywords: planetary systems - methods: data analysis -
techniques: radial velocities - techniques: spectroscopic
Abstract:
The detection of Earth-like planets with the radial velocity (RV)
method is extremely challenging today due to the presence of
non-Doppler signatures such as stellar activity and instrumental
signals that mimic and hide the signals of exoplanets. In a previous
paper, we presented the YARARA pipeline, which implements corrections
for telluric absorption, stellar activity, and instrumental
systematics at the spectral level, and then it extracts line-by-line
(LBL) RVs with a significantly better precision than standard
pipelines.
In this paper, we demonstrate that further gains in RV precision can
be achieved by performing principal component analysis (PCA)
decomposition on the LBL RVs.
The mean-insensitive nature of PCA means that it is unaffected by true
Doppler shifts, and thus can be used to isolate and correct nuisance
signals other than planets.
We analysed the data of 20 intensively observed HARPS targets by
applying our PCA approach on the LBL RVs obtained by YARARA. The first
principal components show similarities across most of the stars and
correspond to newly identified instrumental systematics for which we
can now correct. For several targets, this results in an unprecedented
RV root-mean-square of around 90cm/s over the full lifetime of HARPS.
We used the corrected RVs to confirm a previously published 120-day
signal around 61 Vir, and to detect a super-Earth candidate
(K∼60±6cm/s, msini=6.6±0.7M+⊕_) around the G6V star
HD 20794, which spends part of its 600-day orbit within the habitable
zone of the host star.
This study highlights the potential of LBL PCA to identify and correct
hitherto unknown, long-term instrumental effects and thereby extend
the sensitivity of existing and future instruments towards the Earth
analogue regime.
Description:
DRS time-series are given by the HARPS v.3.5 DRS.
YV1 time-series are obtained from the spectra time-series cleaned by
YARARA (Cretignier et al. 2021A&A...653A..43C 2021A&A...653A..43C). YV2 time-series are
the YV1 time-series corrected by the linear predictors and accounting
for detected planetary signals. Shell time-series derivations are
explained in the paper.
Objects:
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RA (2000) DE Designation(s)
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20 15 17.39 -27 01 58.7 HD 192310 = TIC 326096771
13 18 24.31 -18 18 40.2 HD 115617 = TIC 422478973
12 33 31.38 -68 45 20.9 HD 109200 = TIC 326538408
03 19 55.65 -43 04 11.2 HD 20794 = TIC 301051051
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
hd109200.dat 142 357 HD 109200 DRS, YV1 and YV2 RV time series
hd115617.dat 184 201 HD 115617 DRS, YV1 and YV2 RV time series
hd192310.dat 183 319 HD 192310 DRS, YV1 and YV2 RV time series
hd20794.dat 213 468 HD 20794 DRS, YV1 and YV2 RV time series
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Byte-by-byte Description of file: hd109200.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [0/356] Index of the table
5- 16 F12.6 d Time Time (JD-2400000)
18- 26 F9.6 m/s RVDRS DRS radial velocity
28- 35 F8.6 m/s e_RVDRS DRS radial velocity uncertainty + 0.70m/s
added quad.
37- 45 F9.6 m/s RVYV1 YV1 radial velocity
47- 54 F8.6 m/s e_RVYV1 YV1 radial velocity uncertainty + 0.70m/s
added quad.
56- 64 F9.6 m/s RVYV2 YV2 radial velocity
66- 73 F8.6 m/s e_RVYV2 YV2 radial velocity uncertainty + 0.70m/s
added quad.
75- 83 F9.6 --- ctm-shell1 Unscaled linear predictor shell 1
85- 93 F9.6 --- ctm-shell2 Unscaled linear predictor shell 2
95-103 F9.6 --- ctm-shell3 Unscaled linear predictor shell 3
105-113 F9.6 --- ctm-shell4 Unscaled linear predictor shell 4
115-123 F9.6 --- ctm-shell5 Unscaled linear predictor shell 5
125-133 F9.6 --- ctm-slice1 Unscaled linear predictor slice 1
135-142 E8.2 --- ctm-slice2 Unscaled linear predictor slice 2
--------------------------------------------------------------------------------
Byte-by-byte Description of file: hd115617.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [0/200] Index of the table
5- 16 F12.6 d Time Time (JD-2400000)
18- 27 F10.6 m/s RVDRS DRS radial velocity
29- 36 F8.6 m/s e_RVDRS DRS radial velocity uncertainty + 0.70m/s
added quad.
38- 46 F9.6 m/s RVYV1 YV1 radial velocity
48- 55 F8.6 m/s e_RVYV1 YV1 radial velocity uncertainty + 0.70m/s
added quad.
57- 65 F9.6 m/s RVYV2 YV2 radial velocity
67- 74 F8.6 m/s e_RVYV2 YV2 radial velocity uncertainty + 0.70m/s
added quad.
76- 84 F9.6 --- ctm-shell1 Unscaled linear predictor shell 1
86- 94 F9.6 --- ctm-shell2 Unscaled linear predictor shell 2
96-104 F9.6 --- ctm-shell3 Unscaled linear predictor shell 3
106-114 F9.6 --- ctm-shell4 Unscaled linear predictor shell 4
116-124 F9.6 --- ctm-shell5 Unscaled linear predictor shell 5
126-134 F9.6 --- ctm-slice1 Unscaled linear predictor slice 1
136-144 F9.6 --- ctm-slice2 Unscaled linear predictor slice 2
146-154 F9.6 --- ctm-color1 Unscaled linear predictor color 1
156-164 F9.6 --- ctm-color2 Unscaled linear predictor color 2
166-174 F9.6 --- ctm-lbl1 Unscaled linear predictor lbl 1
176-184 F9.6 --- ctm-lbl2 Unscaled linear predictor lbl 2
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Byte-by-byte Description of file: hd192310.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [0/318] Index of the table
5- 16 F12.6 d Time Time (JD-2400000)
18- 26 F9.6 m/s RVDRS DRS radial velocity
28- 35 F8.6 m/s e_RVDRS DRS radial velocity uncertainty + 0.70m/s
added quad.
37- 45 F9.6 m/s RVYV1 YV1 radial velocity
47- 54 F8.6 m/s e_RVYV1 YV1 radial velocity uncertainty + 0.70m/s
added quad.
56- 64 F9.6 m/s RVYV2 YV2 radial velocity
66- 73 F8.6 m/s e_RVYV2 YV2 radial velocity uncertainty + 0.70m/s
added quad.
75- 83 F9.6 --- ctm-shell1 Unscaled linear predictor shell 1
85- 93 F9.6 --- ctm-shell2 Unscaled linear predictor shell 2
95-103 F9.6 --- ctm-shell3 Unscaled linear predictor shell 3
105-113 F9.6 --- ctm-shell4 Unscaled linear predictor shell 4
115-123 F9.6 --- ctm-shell5 Unscaled linear predictor shell 5
125-133 F9.6 --- ctm-shell6 Unscaled linear predictor shell 6
135-143 F9.6 --- ctm-shell7 Unscaled linear predictor shell 7
145-153 F9.6 --- ctm-slice1 Unscaled linear predictor slice 1
155-163 F9.6 --- ctm-slice2 Unscaled linear predictor slice 2
165-173 F9.6 --- ctm-color1 Unscaled linear predictor color 1
175-183 F9.6 --- ctm-lbl1 Unscaled linear predictor lbl 1
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Byte-by-byte Description of file: hd20794.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [0/467] Index of the table
5- 16 F12.6 d Time Time (JD-2400000)
18- 26 F9.6 m/s RVDRS DRS radial velocity
28- 35 F8.6 m/s e_RVDRS DRS radial velocity uncertainty + 0.70m/s
added quad.
37- 45 F9.6 m/s RVYV1 YV1 radial velocity
47- 54 F8.6 m/s e_RVYV1 YV1 radial velocity uncertainty + 0.70m/s
added quad.
56- 64 F9.6 m/s RVYV2 YV2 radial velocity
66- 73 F8.6 m/s e_RVYV2 YV2 radial velocity uncertainty + 0.70m/s
added quad.
75- 83 F9.6 --- ctm-shell1 Unscaled linear predictor shell 1
85- 93 F9.6 --- ctm-shell2 Unscaled linear predictor shell 2
95-103 F9.6 --- ctm-shell3 Unscaled linear predictor shell 3
105-113 F9.6 --- ctm-shell4 Unscaled linear predictor shell 4
115-123 F9.6 --- ctm-shell5 Unscaled linear predictor shell 5
125-133 F9.6 --- ctm-slice1 Unscaled linear predictor slice 1
135-143 F9.6 --- ctm-slice2 Unscaled linear predictor slice 2
145-153 F9.6 --- ctm-color1 Unscaled linear predictor color 1
155-163 F9.6 --- ctm-color2 Unscaled linear predictor color 2
165-173 F9.6 --- ctm-color3 Unscaled linear predictor color 3
175-183 F9.6 --- ctm-lbl1 Unscaled linear predictor lbl 1
185-193 F9.6 --- ctm-lbl2 Unscaled linear predictor lbl 2
195-203 F9.6 --- ctm-lbl3 Unscaled linear predictors lbl 3
205-213 F9.6 --- ctm-lbl4 Unscaled linear predictors lbl 4
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Acknowledgements:
Michael Cretignier, michael.cretignier(at)unige.ch
References:
Cretignier et al., 2021A&A...653A..43C 2021A&A...653A..43C,
YARARA: Significant improvement in RV precision through post-processing
of spectral time series
Cretignier et al., 2022A&A...659A..68C 2022A&A...659A..68C,
Stellar activity correction using PCA decomposition of shells
(End) Patricia Vannier [CDS] 21-Aug-2023