J/A+A/696/A27 CARMENES. Dependence of RV measurements (Jeffers+, 2025)
The CARMENES search for exoplanets around M dwarfs.
Understanding the wavelength dependence of radial velocity measurements.
Jeffers S.V., Barnes J.R., Schoefer P., Reffert S., Bejar V.J.S.,
Quirrenbach A., Reiners A., Shan Y., Zapatero Osorio M.R., Fuhrmeister B.,
Amado P.J., Caballero J.A., Ribas I., Cardona Guillen C., Del Sordo F.,
Fernandez M., Garcia-Lopez A., Guijarro A., Hatzes A.P., Lafarga M.,
Lodieu N., Kuerster M., Molaverdikhani K., Montes D., Morales J.C.
<Astron. Astrophys. 696, A27 (2025)>
=2025A&A...696A..27J 2025A&A...696A..27J (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, M-type ; Exoplanets ;
Radial velocities ; Rotational velocities
Keywords: techniques: radial velocities - planets and satellites: detection -
stars: activity - stars: low-mass - stars: magnetic field -
stars: starspots
Abstract:
Current exoplanet surveys are focused on detecting small exoplanets
orbiting in the liquid-water habitable zones of their host stars.
Despite recent significant advancements in instrumentation, the main
limitation in detecting these exoplanets is the intrinsic variability
of the host star itself.
Our aim is to investigate the wavelength dependence of high-precision
radial velocities (RV), as stellar activity induced RVs should exhibit
a wavelength dependence while the RV variation due to an orbiting
planet will be wavelength independent.
We used the chromatic index (CRX) to quantify the slope of the
measured RVs as a function of logarithmic wavelength of the full
CARMENES guaranteed time observations (GTO) data set spanning more
than eight years of observations of over 350 stars. We investigated
the dependence of the CRX in the full Carmenes GTO sample on 24
stellar activity indices in the visible and near-infrared channels of
the CARMENES spectrograph and each star;s stellar parameters. We
also present an updated convective turnover time scaling for the
calculation of the stellar Rossby number for M dwarfs.
Our results show that approximately 17% of GTO stars show a strong or
a moderate correlation between the CRX and RV. We can improve the
measured RVs by a factor of up to nearly 4 in terms of the root mean
square (rms) by subtracting the RV predicted by the CRX-RV correlation
from the measured RVs. Mid-M dwarfs with moderate rotational
velocities and moderate CRX-gradients, with quasi-stable activity
features, have the best rms improvement factors.
We conclude that the CRX is a powerful diagnostic in mitigation of
stellar activity and the search for low mass rocky planets.
Description:
The sample of stars used for our analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 156 224 Sample of stars used for our analysis
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Karmn CARMENES star name
12- 34 A23 --- Name Alternative star name
36- 41 A6 --- SpType Spectral Type
43- 45 I3 --- Nobs Number of observations
47- 50 I4 K Teff ? Stellar effective temperature
52- 59 F8.6 Rsun R ? Stellar radius
61- 68 F8.6 Msun M ? Stellar mass
70- 75 F6.2 km/s vsini ? Rotational velocity
77- 82 A6 --- r_vsini Reference of vsini (1)
84- 90 F7.3 0.1nm pEWHa ? Halpha pseudo-equivalent width
92- 95 I4 G B ? Average magnetic field strength
97-101 F5.3 mag V-Ks ? V-Ks colour index
103-109 F7.5 [s] logtau ? Log Convective turnover time
111-121 F11.9 0.1nm TiO7050 ? TiO λ7050Å equivalent width
123-130 F8.4 d Prot ? Stellar rotation period
132-137 A6 --- r_Prot Reference stellar rotation period (2)
139-149 F11.5 m/s CRXl ? Chromatic index CRX length
151-156 F6.2 --- CRXs ? Chromatic index CRX slope
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Note (1): References of vsini as follows:
Bro10 = Browning et al. (2010AJ....139..504B 2010AJ....139..504B)
Del98 = Delfosse et al. (1998A&A...331..581D 1998A&A...331..581D, Cat. J/A+A/331/581)
Jeff18 = Jeffers et al. (2018A&A...614A..76J 2018A&A...614A..76J, Cat. J/A+A/614/A76)
Jen09 = Jenkins et al. (2009ApJ...704..975J 2009ApJ...704..975J, Cat. J/ApJ/704/975)
LS10 = Lopez-Santiago et al. (2010A&A...514A..97L 2010A&A...514A..97L, Cat. J/A+A/514/A97)
Mora09 = Morales et al. (2009ApJ...691.1400M 2009ApJ...691.1400M, Cat. J/ApJ/691/1400)
MR14 = Lafarga et al. (2021A&A...652A..28L 2021A&A...652A..28L, Cat. J/A+A/652/A28)
Rein18 = Reiners et al. (2018A&A...612A..49R 2018A&A...612A..49R, Cat. J/A+A/612/A49)
Rei22 = Reiners et al. (2022A&A...662A..41R 2022A&A...662A..41R, Cat. J/A+A/662/A41)
Tor06 = Torres et al. (2006A&A...460..695T 2006A&A...460..695T, Cat. J/A+A/460/695)
Note (2): References of the rotation period as follows:
Ama21 = Amado et al., (2021A&A...650A.188A 2021A&A...650A.188A, Cat. J/A+A/650/A186)
Bidd14 = Biddle et al. (2014MNRAS.443.1810B 2014MNRAS.443.1810B)
Blu20 = Blum et al. 2020A&A...639A.132B 2020A&A...639A.132B
CC21 = Collier Cameron et al. (2021MNRAS.505.1699C 2021MNRAS.505.1699C)
Cab23 = Fuhrmeister et al. (2023A&A...678A...1F 2023A&A...678A...1F, Cat. J/A+A/678/A1)
DA19 = Diez Alonso et al. (2019A&A...621A.126D 2019A&A...621A.126D, Cat. J/A+A/621/A126)
Dev08 = Devor et al. (2008AJ....135..850D 2008AJ....135..850D, Cat. J/AJ/135/850)
Dia19 = DIAZ et al. (2019A&A...625A..17D 2019A&A...625A..17D, Cat. J/A+A/625/A17)
Don23 = Donati et al. (2023MNRAS.525.2015D 2023MNRAS.525.2015D)
Drei20 = Dreizler et al. (2020A&A...644A.127D 2020A&A...644A.127D, Cat. J/A+A/644/A127)
Fou23 = Fouque et al. (2023A&A...672A..52F 2023A&A...672A..52F)
Gor23 = Gorrini et al. (2023A&A...680A..28G 2023A&A...680A..28G, Cat. J/A+A/680/A28)
Hart11 = HARTMAN et al. (2011AJ....141..166H 2011AJ....141..166H, Cat. J/AJ/141/166)
Irv23 = Irving et al. (2023ApJ...949...51I 2023ApJ...949...51I)
Irw11 = Irving et al. (2011ApJ...727...56I 2011ApJ...727...56I)
Kir12 = Kiraga (2012AcA....62...67K 2012AcA....62...67K, Cat. J/AcA/62/67)
Laf21 = Lafarga et al. (2021A&A...652A..28L 2021A&A...652A..28L, Cat. J/A+A/652/A28)
Luq18 = Luque et al. (2018A&A...620A.171L 2018A&A...620A.171L, Cat. J/A+A/620/A171)
Luq19 = Luque et al. (2019A&A...628A..39L 2019A&A...628A..39L, Cat. J/A+A/628/A39)
Luq22 = Luque et al. (2022A&A...664A.199L 2022A&A...664A.199L)
Mori08 = Morin et al. (2008MNRAS.390..567M 2008MNRAS.390..567M, Cat. J/MNRAS/490/567)
Mori10 = Morin et al. (2010MNRAS.407.2269M 2010MNRAS.407.2269M, Cat. J/MNRAS/407/2269)
New16a = Newton et al. (2016ApJ...821...93N 2016ApJ...821...93N, Cat. J/ApJ/821/93)
New18 = Newton et al. (2018AJ....156..217N 2018AJ....156..217N, Cat. J/AJ/156/217)
Pass23 = Pass et al. (2023AJ....166...16P 2023AJ....166...16P, Cat. J/AJ/166/16)
Rae20 = Raetz et al. (2020A&A...637A..22R 2020A&A...637A..22R, Cat. J/A+A/637/A22)
Sha24 = Shan et al. (2024A&A...684A...9S 2024A&A...684A...9S, Cat. J/A+A/684/A9)
SM15 = Suarez Mascareno et al. (2015MNRAS.452.2745S 2015MNRAS.452.2745S)
SM17b = Suarez-Mascareno et al. (2017MNRAS.468.4772S 2017MNRAS.468.4772S)
SM18 = Suarez Mascareno et al. (2018A&A...612A..89S 2018A&A...612A..89S)
Sha24 = SHAN et al. (2024A&A...684A...9S 2024A&A...684A...9S, Cat. J/A+A/684/A95)
Ste16 = Stelzer (2016MNRAS.463.1844S 2016MNRAS.463.1844S, Cat. J/MNRAS/463/1844)
Tol19 = Toledo-Padron et al. (2019MNRAS.488.5145T 2019MNRAS.488.5145T)
Wat06 = Watson et al. (2006SASS...25...47W 2006SASS...25...47W, Cat. B/vsx)
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Acknowledgements:
Sandra Jeffers, sandrajeffers.astro(at)gmail.com
(End) Patricia Vannier [CDS] 25-Mar-2025