J/A+A/697/A32 Precise radial velocities of giant stars. XVII. (Spaeth+, 2025)
Precise radial velocities of giant stars.
XVII. Distinguishing planets from intrinsically induced radial velocity signals
in evolved stars.
Spaeth D., Reffert S., Trifonov T., Kaminski A., Albrecht S., Grundahl F.,
Fredslund Andersen M., Quirrenbach A., Palle P.
<Astron. Astrophys. 697, A32 (2025)>
=2025A&A...697A..32S 2025A&A...697A..32S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Exoplanets ; Radial velocities ; Optical ;
Spectroscopy
Keywords: techniques: radial velocities - planets and satellites: detection -
stars: evolution - stars: oscillations - planetary systems
Abstract:
From a long-term Doppler monitoring campaign of 373 giant stars, we
have identified ten giants with periodic radial velocity
variations that are challenging to associate with planets. Similar
cases in the literature are attributed to poorly understood intrinsic
processes.
Our goal is to confirm or refute the presence of planets around these
ten evolved stars. Additionally, we evaluate the reliability and
sensitivity of planet-confirmation metrics when applied to giant stars
and present cases of intrinsically induced radial velocity variations,
aiming to enhance the physical understanding of the phenomenon.
We combined 25 years of radial velocity data from the Hamilton/Lick,
SONG, and CARMENES spectrographs. To assess consistency with Keplerian
models, we examined the residuals and tracked changes in statistical
significance as new data were incorporated. Additionally, we compared
radial velocity amplitudes across optical and infrared wavelengths,
searched for periodic variations of activity indicators, and examined
their correlations with radial velocities.
Seven of the ten giants exhibit intrinsically induced radial velocity
variations. The strongest arguments against planets orbiting the
giants are guided by long-term radial velocity monitoring that detects
changing periodicity on long timescales or detects systematics close
to the original period in the radial velocity residuals. While
activity indicators offer some support, their signals are generally
weak. Comparing optical and infrared radial velocity amplitudes also
proves insufficient for confirming or refuting planets. We find HIP
64823 remains a promising candidate for hosting a giant exoplanet with
orbital period P=7.75yr. For two stars, the evidence remains
inconclusive.
Long-term radial velocity monitoring is essential for distinguishing
planetary companions from intrinsic variations in evolved stars.
Description:
Each table contains the radial velocities and activity indicator
measurements for all the stars from a specific instrument. In total,
2831 measurements for twelve stars are available from the
Hamilton/Lick, SONG (only for HIP38253, HIP46390, HIP47959 and HIP75458),
and CARMENES spectrographs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 59 12 List of studied stars
lick.dat 57 1127 Radial velocities and Halpha measurements
measured by the Hamilton Echelle spectrograph at
Lick observatory (Vogt, 1987PASP...99.1214V 1987PASP...99.1214V)
song.dat 41 1030 Radial velocities measured by the Hertzsprung SONG
spectrograph at Teide observatory
(Andersen et al., 2014RMxAC..45...83A 2014RMxAC..45...83A)
carmvis.dat 198 627 Radial velocities and activity indicators measured
by the VIS channel of the CARMENES spectrograph
at Calar Alto Astronomical Observatory
(Quirrenbach et al., 2014SPIE.9147E..1FQ)
carmnir.dat 101 337 Radial velocities and activity indicators measured
by the NIR channel of the CARMENES spectrograph
at Calar Alto Astronomical Observatory
(Quirrenbach et al., 2014SPIE.9147E..1FQ)
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See also:
J/A+A/475/1003 : Stellar parameters of G and K giant stars (Hekker+, 2007)
J/A+A/574/A116 : G and K giant stars stellar parameters (Reffert+, 2015)
J/A+A/647/A160 : Radial velocity data of epsilon Cyg (Heeren+, 2021)
J/A+A/661/A63 : Precise radial velocities of giant stars. XVI.
(Wolthoff+, 2022)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 20 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 33 F5.2 arcsec DEs Declination (J2000)
35- 38 A4 ---- Lick Indicates RV data in lick.dat file
40- 43 A4 ---- SONG Indicates RV data in song.dat file
45- 51 A7 --- CarmVIS Indicates RV data in carmvis.dat file
53- 59 A7 --- CarmNIR Indicates RV data in carmnir.dat file
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Byte-by-byte Description of file: lick.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Star name
10- 12 I3 --- Seq Line sequential number
14- 27 F14.6 d JD Julian Date
29- 34 F6.1 m/s RV Radial velocity
36- 39 F4.1 m/s e_RV Uncertainty in radial velocity
41- 47 F7.5 --- Halpha Halpha line index measurement
49- 55 F7.5 --- e_Halpha Uncertainty in Halpha line index measurement
57 I1 --- CCD [6/8] Identifier of CCD, used for separating
the Halpha data sets
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Byte-by-byte Description of file: song.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Star name
10- 12 I3 --- Seq Line sequential number
14- 27 F14.6 d BJD Barycentric Julian Date reduced by pyodine;
Heeren et al., 2023A&A...674A.164H 2023A&A...674A.164H
29- 36 F8.1 m/s RV Radial velocity reduced by pyodine
38- 41 F4.1 m/s e_RV Uncertainty in radial velocity reduced by pyodine
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Byte-by-byte Description of file: carmvis.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Star name
10- 11 I2 --- Seq Line sequential number
13- 26 F14.6 d BJD Barycentric Julian Date reduced by SERVAL
(Zechmeister et al., 2018A&A...609A..12Z 2018A&A...609A..12Z)
28- 33 F6.1 m/s RV Radial Velocity reduced by SERVAL
35- 37 F3.1 m/s e_RV Uncertainty in radial velocity reduced
by SERVAL
39- 44 F6.1 --- CRX Chromatic index reduced by SERVAL (in m/s/Np)
46- 49 F4.1 --- e_CRX Uncertainty in chromatic index reduced
by SERVAL (in m/s/Np)
51- 56 F6.1 1000m2/s2 dLW Differential linewidth reduced by SERVAL
58- 61 F4.1 1000m2/s2 e_dLW Uncertainty in differential linewidth
reduced by SERVAL
63- 69 F7.5 --- Halpha Halpha line index measurement reduced
by SERVAL
71- 77 F7.5 --- e_Halpha Uncertainty in Halpha line index
measurement reduced by SERVAL
79- 85 F7.5 --- NaD1 NaD1 line index measurement reduced
by SERVAL
87- 93 F7.5 --- e_NaD1 Uncertainty in NaD1 line index measurement
reduced by SERVAL
95-101 F7.5 --- NaD2 NaD2 line index measurement reduced
by SERVAL
103-109 F7.5 --- e_NaD2 Uncertainty in NaD2 line index measurement
reduced by SERVAL
111-117 F7.5 --- CaIRT1 CaIRT1 line index measurement reduced
by SERVAL
119-125 F7.5 --- e_CaIRT1 Uncertainty in CaIRT1 line index
measurement reduced by SERVAL
127-133 F7.5 --- CaIRT2 CaIRT2 line index measurement reduced
by SERVAL
135-141 F7.5 --- e_CaIRT2 Uncertainty in CaIRT2 line index
measurement reduced by SERVAL
143-149 F7.5 --- CaIRT3 CaIRT3 line index measurement reduced
by SERVAL
151-157 F7.5 --- e_CaIRT3 Uncertainty in CaIRT3 line index
measurement reduced by SERVAL
159-164 F6.3 km/s FWHM Full width at half maximum of
cross-correlation function reduced
by RACCOON
(Lafarga et al., 2020A&A...636A..36L 2020A&A...636A..36L)
166-170 F5.3 km/s e_FWHM Uncertainty in full width at half maximum
of cross-correlation function reduced
by RACCOON
172-177 F6.3 % Cont Contrast of cross-correlation function
reduced by RACCOON
179-183 F5.3 % e_Cont Uncertainty in contrast of
cross-correlation function reduced
by RACCOON
185-191 F7.4 km/s BIS Bisector inverse slop reduced by RACCOON
193-198 F6.4 km/s e_BIS Uncertainty in Bisector inverse slop
reduced by RACCOON
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Byte-by-byte Description of file: carmnir.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Star name
10- 11 I2 --- Seq Line sequential number
13- 26 F14.6 d BJD Barycentric Julian Date reduced by SERVAL
28- 33 F6.1 m/s RV Radial Velocity reduced by SERVAL
35- 38 F4.1 m/s e_RV Uncertainty in radial velocity reduced
by SERVAL
40- 45 F6.1 --- CRX Chromatic index reduced by SERVAL
47- 51 F5.1 --- e_CRX Uncertainty in chromatic index reduced
by SERVAL
53- 57 F5.1 1000m2/s2 dLW Differential linewidth reduced by SERVAL
(in m/s/Np)
59- 62 F4.1 1000m2/s2 e_dLW Uncertainty in differential linewidth
reduced by SERVAL (in m/s/Np)
64- 69 F6.3 km/s FWHM Full width at half maximum of
cross-correlation function reduced
by RACCOON
71- 75 F5.3 km/s e_FWHM Uncertainty in full width at half maximum
of cross-correlation function reduced
by RACCOON
77- 82 F6.3 % Cont Contrast of cross-correlation function
reduced by RACCOON
84- 88 F5.3 % e_Cont Uncertainty in contrast of
cross-correlation function reduced
by RACCOON
90- 95 F6.3 km/s BIS Bisector inverse slop reduced by RACCOON
97-101 F5.3 km/s e_BIS Uncertainty in bisector inverse slop
reduced by RACCOON
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History:
From Dane Spaeth, dane.spaeth(at)lsw.uni-heidelberg.de
Acknowledgements:
We would like to thank the staff at Lick observatory for their support
and thank the CAT observers who assisted with this project, including
David Mitchell, Saskia Hekker, Christian Schwab, Christoph Bergmann,
Kirsten Vincke, Julian Stuermer, Kelsey Clubb, David Bauer, Dominika
Wylezalek, Dennis Kuegler, and Debra Fischer. This work is based on
observations made with the Hertzsprung SONG telescope operated on the
Spanish Observatorio del Teide on the island of Tenerife by the Aarhus
and Copenhagen Universities and by the Instituto de Astrofisica de
Canarias. It is further based on observations collected at the Centro
Astronomico Hispano en Andalucia (CAHA) at Calar Alto, proposals
F16-3.5-024, H17-3.5-014, F18-3.5-016, H18-3.5-015, 21A-3.5-051,
21B-3.5-052, 22A-3.5-051, 22B-3.5-051, 23A-3.5-051, 23B-3.5-052,
operated jointly by Junta de Andalucia and Consejo Superior de
Investigaciones Cientificas (IAA-CSIC). Based on data from the CAHA
Archive at CAB (INTA-CSIC) (http://cab.inta.es/) The CAHA Archive is
part of the Spanish Virtual Observatory (http://svo.cab.inta-csic.es/)
project funded by MCIN/AEI/10.13039/501100011033 through grant
PID2020-112949GB-I00.
This project has received funding from the European Union's Horizon
2020 research and innovation programme under grant agreement No
101004719.
References:
Hekker et al., Paper I 2006A&A...454..943H 2006A&A...454..943H
Reffert et al., Paper II 2006ApJ...652..661R 2006ApJ...652..661R
Hekker & Melendez, Paper III 2007A&A...475.1003H 2007A&A...475.1003H, Cat. J/A+A/475/1003
Hekker et al., Paper IV 2008A&A...480..215H 2008A&A...480..215H
Mitchell et al., Paper V 2013A&A...555A..87M 2013A&A...555A..87M
Trifonov et al., Paper VI 2014A&A...568A..64T 2014A&A...568A..64T
Reffert et al., Paper VII 2015A&A...574A.116R 2015A&A...574A.116R, Cat. J/A+A/574/A116
Trifonov et al., Paper VIII 2015A&A...582A..54T 2015A&A...582A..54T
Ortiz et al., Paper IX 2016A&A...595A..55O 2016A&A...595A..55O
Stock et al., Paper X 2018A&A...616A..33S 2018A&A...616A..33S
Quirrenbach et al., Paper XI 2019A&A...624A..18Q 2019A&A...624A..18Q
Reichert et al., Paper XII 2019A&A...625A..22R 2019A&A...625A..22R
Luque et al., Paper XIII 2019A&A...631A.136L 2019A&A...631A.136L
Tala Pinto et al., Paper XIV 2020A&A...644A...1T 2020A&A...644A...1T
Heeren et al., Paper XV 2021A&A...647A.160H 2021A&A...647A.160H, Cat. J/A+A/647/A160
Wolthoff et al., Paper XVI 2022A&A...661A..63W 2022A&A...661A..63W, Cat. J/A+A/661/A63
(End) Patricia Vannier [CDS] 08-Apr-2025