J/A+A/693/A297 HD 20794 RV, FWHM, BIS, S-index, Ha, Temp (Nari+, 2025)
Revisiting the multi-planetary system of the nearby star HD 20794.
Nari N., Dumusque X., Hara N.C., Suarez Mascareno A., Cretignier M.,
Gonzalez Hernandez J.I., Stefanov A.K., Passegger V.M., Rebolo R., Pepe F.,
Santos N.C., Cristiani S., Faria J.P., Figueira P., Sozzetti A.,
Zapatero Osorio M.R., Adibekyan V., Alibert Y., Allende Prieto C.,
Bouchy F., Benatti S., Castro-Gonzalez A., D'Odorico V., Damasso M.,
Delisle J.B., Di Marcantonio P., Ehrenreich D., Genova-Santos R.,
Hobson M.J., Lavie B., Lillo-Box J., Lo Curto G., Lovis C.,
Martins C.J.A.P., Mehner A., Micela G., Molaro P., Mordasini C., Nunes N.,
Palle E., Quanz S.P., Segransan D., Silva A.M., Sousa S.G., Udry S.,
Unger N., Venturini J.
<Astron. Astrophys. 693, A297 (2025)>
=2025A&A...693A.297N 2025A&A...693A.297N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities;
Optical
Keywords: techniques: spectroscopic - techniques: radial velocities -
planets and satellites: detection - stars: activity -
planets and satellites: terrestrial planets -
stars: individual: HD 20794
Abstract:
Close-by Earth analogs and super-Earths are of primary importance
because they will be preferential targets for the next generation of
direct imaging instruments. Bright and close-by G-to-M type stars are
preferential targets in radial velocity surveys to find Earth analogs.
Their brightness allows us to achieve the best precision on RV
measurements and search for signals with amplitudes of less than 1m/s.
We present an analysis of the RV data of the star HD 20794, a target
whose planetary system has been extensively debated in the literature.
The broad time span of the observations makes it possible to find
planets with signal semi-amplitudes below 1m/s in the habitable zone.
We analyzed RV datasets spanning more than 20 years. We monitored the
system with ESPRESSO. We joined ESPRESSO data with the HARPS data,
including archival data and new measurements from a recent program. We
applied the post-processing pipeline YARARA to HARPS data to correct
systematics, improve the quality of RV measurements, and mitigate the
impact of stellar activity.
We confirm the presence of three planets, with periods of
18.3142±0.0022d, 89.68±0.10d, and 647.6±2.6d, along with masses
of 2.15±0.17M⊕, 2.98±0.29M⊕, and
5.82±0.57M⊕ respectively. For the outer planet, we find an
eccentricity of 0.45±0.11 , whereas the inner planets are compatible
with circular orbits. The latter is likely to be a rocky planet in the
habitable zone of HD 20794. From the analysis of activity indicators,
we find evidence of a magnetic cycle with a period of ∼3000d, along
with evidence pointing to a rotation period of ∼39d.
We have determined the presence of a system of three planets orbiting
the solar-type star HD 20794. This star is bright (V=4.34mag) and
close (d=6.04pc), and HD 20794 d resides in the stellar habitable
zone, making this system a high-priority target for future atmospheric
characterization with direct imaging facilities.
Description:
Time series of HD20794 for RV, FWHM, BIS, Contrast, S-index, Contrast,
Na, Echelle temperatures.
Objects:
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RA (2000) DE Designation(s)
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03 19 55.65 -43 04 11.2 HD 20794 = * e Eri
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
harps03.dat 223 514 HARPS data using YARARA v2 (09/2003-02/2015)
harps15.dat 223 232 HARPS data using YARARA v1 (08/2015-03/2024)
harpsdrs.dat 317 8217 HARPS data using DRS (11/2010-10/2013)
espsbart.dat 56 695 ESPRESSO data using SBART (10/2018-03/2023)
esp19drs.dat 170 656 ESPRESSO data using DRS (08/2019-03/2023)
tesp19.dat 31 656 ESPRESSO echelle temperature (21/10/2021)
esp18drs.dat 163 29 ESPRESSO data using DRS (10/2018-02/2018)
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See also:
J/A+A/605/A103 : HD20794 HARPS radial velocities (Feng+, 2017)
J/A+A/534/A58 : HD20794, HD85512, HD192310 HARPS radial velocities
(Pepe+, 2011)
Byte-by-byte Description of file: harps03.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Observation date (BJD-2400000)
14- 28 F15.12 m/s RV RV variation from the average of observations
30- 41 F12.10 m/s e_RV Uncertainty on RV
43- 52 F10.8 km/s FWHM FWHM measurement
54- 67 F14.12 km/s e_FWHM Uncertainty on FWHM
69- 80 F12.10 km/s BisSpan Bisector measurement
82- 96 F15.13 km/s e_BisSpan Uncertainty on bisector
98-108 F11.9 --- Contrast Contrast of the CCF measurement
110-124 F15.13 --- e_Contrast Uncertainty on the contrast
126-137 F12.9 --- SMW S-index measurement
139-153 F15.13 --- e_SMW Uncertainty on S-index
155-165 F11.9 --- Ha H-alpha measurement
167-181 F15.13 --- e_Ha Uncertainty on H-alpha
183-193 F11.9 --- Na Na I D activity measurement
195-209 F15.13 --- e_Na Uncertainty on Na I D activity
211-223 F13.9 km/s BERV Barycentric Earth Radial velocity
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Byte-by-byte Description of file: harps15.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Observation date (BJD-2400000)
14- 27 F14.11 m/s RV RV variation from the average of observations
29- 40 F12.10 m/s e_RV Uncertainty on RV
42- 51 F10.8 km/s FWHM FWHM measurement
53- 66 F14.12 km/s e_FWHM Uncertainty on FWHM
68- 79 F12.10 km/s BisSpan Bisector measurement
81- 95 F15.13 km/s e_BisSpan Uncertainty on bisector
97-107 F11.9 --- Contrast Contrast of the CCF measurement
109-123 F15.13 --- e_Contrast Uncertainty on the contrast
125-136 F12.9 --- SMW S-index measurement
138-152 F15.13 --- e_SMW Uncertainty on S-index
154-164 F11.9 --- Ha H-alpha measurement
166-180 F15.13 --- e_Ha Uncertainty on H-alpha
182-192 F11.9 --- Na Na I D activity measurement
194-208 F15.13 --- e_Na Uncertainty on Na I D activity
210-223 F14.10 km/s BERV Barycentric Earth Radial velocity
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Byte-by-byte Description of file: harpsdrs.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Observation date, BJD
18- 33 F16.13 km/s RV RV measurement
35- 54 F20.18 km/s e_RV Uncertainty on RV
56- 72 F17.15 km/s FWHM FWHM measurement
74- 93 F20.18 km/s e_FWHM Uncertainty on FWHM
95-113 F19.16 km/s BisSpan Bisector measurement
115-134 F20.18 km/s e_BisSpan Uncertainty on bisector
136-152 F17.13 --- Contrast Contrast of the CCF measurement
154-174 F21.17 --- e_Contrast Uncertainty on the contrast
176-195 F20.17 --- SMW S-index measurement
197-218 E22.14 --- e_SMW Uncertainty on S-index
220-237 F18.16 --- Ha H-alpha measurement
239-260 E22.14 --- e_Ha Uncertainty on H-alpha
262-281 F20.17 --- NaI Na I D activity measurement
283-304 E22.14 --- e_NaI Uncertainty on Na I D activity
306-311 F6.3 C eTemp ? Temperature of the echelle grating
313-317 F5.3 C e_eTemp ? Uncertainty on the temperature of the
echelle grating
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Byte-by-byte Description of file: espsbart.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Observation date, BJD
18- 33 F16.13 km/s RV RV measurement
35- 56 E22.14 km/s e_RV Uncertainty on RV
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Byte-by-byte Description of file: esp19drs.dat
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Bytes Format Units Label Explanations
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1- 16 F16.10 d JD Observation date (JD-2400000)
18- 31 F14.6 m/s RV RV measurement
33- 41 F9.6 m/s e_RV Uncertainty on RV
43- 54 F12.6 m/s FWHM FWHM measurement
56- 64 F9.6 m/s e_FWHM Uncertainty on FWHM
66- 76 F11.6 m/s BisSpan Bisector measurement
78- 86 F9.6 m/s e_BisSpan Uncertainty on Bisector
88- 96 F9.6 --- Contrast Contrast of the CCF measurement
98-105 F8.6 --- e_Contrast Uncertainty on the contrast
107-114 F8.6 --- SMW S-index measurement
116-123 F8.6 --- e_SMW Uncertainty on the S-index
125-132 F8.6 --- Ha H-alpha measurement
134-141 F8.6 --- e_Ha Uncertainty on the H-alpha
143-150 F8.6 --- Na Na I D activity measurement
152-159 F8.6 --- e_Na Uncertainty on Na I D activity
161-170 F10.6 km/s BERV Barycentric Earth Radial velocity
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Byte-by-byte Description of file: tesp19.dat
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Bytes Format Units Label Explanations
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1- 18 F18.10 d BJD Observation date, BJD
20- 25 F6.3 C eTemp Temperature of the echelle grating
27- 31 F5.3 C e_eTemp Uncertainty on the temperature of the
echelle grating
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Byte-by-byte Description of file: esp18drs.dat
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Bytes Format Units Label Explanations
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1- 16 F16.10 d JD Observation date (JD-2400000)
18- 29 F12.6 m/s RV RV measurement
31- 38 F8.6 m/s e_RV Uncertainty on RV
40- 50 F11.6 m/s FWHM FWHM measurement
52- 59 F8.6 m/s e_FWHM Uncertainty on FWHM
61- 70 F10.6 m/s BisSpan Bisector measurement
72- 79 F8.6 m/s e_BisSpan Uncertainty on Bisector
81- 89 F9.6 --- Contrast Contrast of the CCF measurement
91- 98 F8.6 --- e_Contrast Uncertainty on the contrast
100-107 F8.6 --- SMW S-index measurement
109-116 F8.6 --- e_SMW Uncertainty on the S-index
118-125 F8.6 --- Ha H-alpha measurement
127-134 F8.6 --- e_Ha Uncertainty on the H-alpha
136-143 F8.6 --- Na Na I D activity measurement
145-152 F8.6 --- e_Na Uncertainty on Na I D activity
154-163 F10.6 km/s BERV Barycentric Earth Radial velocity
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Acknowledgements:
Nicola Nari, nicola.nari(at)lightbridges.es
(End) Patricia Vannier [CDS] 29-Jan-2025