J/A+A/692/A138 Radial velocity jitter in cool stars (Ruh+, 2024)
The CARMENES search for exoplanets around M dwarfs. The impact of rotation and
magnetic fields on the radial velocity jitter in cool stars.
Ruh H.L., Zechmeister M., Reiners A., Nagel E., Shan Y., Cifuentes C.,
Jeffers S.V., Tal-Or L., Bejar V.J.S., Amado P.J., Caballero J.A.,
Quirrenbach A., Ribas I., Aceituno J., Hatzes A.P., Henning T.,
Kaminski A., Montes D., Morales J.C., Schoefer P., Schweitzer A., Varas R.
<Astron. Astrophys. 692, A138 (2024)>
=2024A&A...692A.138R 2024A&A...692A.138R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type; Rotational velocities; Magnetic fields;
Radial velocities
Keywords: techniques: radial velocities - stars: activity - stars: low-mass -
stars: magnetic field - stars: rotation
Abstract:
Radial velocity (RV) jitter represents an intrinsic limitation on the
precision of Doppler searches for exoplanets that can originate from
both instrumental and astrophysical sources.
We aim to determine the RV jitter floor in M dwarfs and investigate
the stellar properties that lead to stellar activity-induced RV
jitter. We determine the RV jitter in 239 M dwarfs from the CARMENES
survey, which are predominantly of mid-to-late spectral type and solar
metallicity. We also investigate the correlation between stellar
rotation and magnetic fields with RV jitter.
The median jitter in the CARMENES sample is 3.1m/s, and 2.3m/s for
stars with an upper limit of 2km/s on their projected rotation
velocities. We provide a relation between the stellar equatorial
rotation velocity and RV jitter in M dwarfs based on a sub-sample of
129 well-characterized CARMENES stars. Stellar rotation-induced RV
jitter dominates for stars with equatorial rotation velocities greater
than 1km/s. A jitter floor of 2m/s dominates in stars with equatorial
rotation velocities below 1km/s. This jitter floor likely contains
contributions from stellar jitter, instrumental jitter and undetected
companions. We study the impact of the average magnetic field and the
distributions of magnetic filling factors on the RV jitter. We find a
series of stars with excess RV jitter and distinctive distributions of
magnetic filling factors, characterized by a dominant magnetic field
component between 2 to 4kG.
A radial velocity jitter floor can be distinguished from
activity-rotation- induced RV jitter based on the stellar equatorial
rotation velocity. Activity-rotation-induced RV jitter depends
primarily on the equatorial rotation velocity.
Activity-rotation-induced RV jitter is also related to the
distribution of magnetic filling factors, emphasizing the role of the
magnetic field in the generation of RV jitter.
Description:
Our sample includes 239 stars with at least 10 observations and with
no known planets or close stellar companions (angular separation less
than 5 arcsec). The table contains stellar properties and radial
velocity jitter computed from the CARMENES visual channel telluric
absorption and nightly zero point corrected radial velocities.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 151 239 CARMENES VIS jitter sample
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Karmn CARMENES star name
13- 35 A23 --- Name Alternative star name
37- 42 F6.4 Rsun R ? Stellar radius in solar units
44- 49 F6.4 Rsun e_R ? Stellar radius in solar units uncertainty
51- 56 F6.2 d Prot ? Stellar rotation period
58- 64 F7.4 d e_Prot ? Stellar rotation period uncertainty
66- 70 A5 --- r_Prot Reference of the rotation period (1)
72- 78 F7.4 km/s veq ? Equatorial velocity
80- 86 F7.4 km/s e_veq ? Equatorial velocity uncertainty
88- 91 F4.1 km/s vsini ? Rotational velocity
93- 95 F3.1 km/s e_vsini ? Rotational velocity uncertainty
97 A1 --- f_vsini Limit flag on vsini
99-104 A6 --- r_vsini Reference of vsini (2)
106-110 F5.2 [-] logRo ? Logarithmic Rossby number of the star
112-115 I4 G B ? Average magnetic field
117-120 I4 G e_B ? Average magnetic field uncertainty
122 A1 --- f_B Limit flag on B
124-127 F4.1 --- z ? Filling factor distribution index
129-131 I3 --- NRV ? Number of radial velocity measurements
133-140 F8.3 m/s sjitter Radial velocity jitter (3)
141 A1 --- n_sjitter [i] i for imaginary (3)
144-150 F7.3 m/s e_sjitter Radial velocity jitter uncertainty
151 A1 --- nesjitter [i] i for imaginary (3)
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Note (1): References of the rotation period as follows:
DA19 = Diez Alonso et al. (2019A&A...621A.126D 2019A&A...621A.126D, Cat. J/A+A/621/A126)
Don23 = Donati et al. (2023MNRAS.525.2015D 2023MNRAS.525.2015D)
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)
Mor10 = Morin et al. (2010MNRAS.407.2269M 2010MNRAS.407.2269M, Cat. J/MNRAS/407/2269)
New16 = 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)
Pas23 = 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)
SM18 = Suarez Mascareno et al. (2018A&A...612A..89S 2018A&A...612A..89S)
Note (2): References of vsini as follows:
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)
Rei18 = Reiners et al. (2018A&A...612A..49R 2018A&A...612A..49R, Cat. J/A+A/612/A49)
Rei22 = Reiners et al. (A&A, 612, 49, Cat. J/A+A/662/A41)
Note (3): The letter i stands for an imaginary jitter value, i.e. a negative
jitter variance sigmajitter2. A negative jitter variance results
from overestimated internal RV uncertainties.
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Acknowledgements:
Henrik Ruh, ruh(at)uni-goettingen.de
(End) Patricia Vannier [CDS] 07-Oct-2024