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J/A+A/607/A124     K-G-F dwarfs stellar granulation variability (Meunier+, 2017)

Variability in stellar granulation and convective blueshift with spectral type and magnetic activity. II. From young to old main-sequence K-G-F stars. Meunier N., Mignon L., Lagrange A.-M. <Astron. Astrophys. 607, A124 (2017)> =2017A&A...607A.124M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Magnetic fields Keywords: convection - techniques: radial velocities - stars: magnetic field - stars: activity - stars: solar-type - Sun: granulation Abstract: The inhibition of small-scale convection in the Sun dominates the long-term radial velocity (RV) variability: it therefore has a critical effect on light exoplanet detectability using RV techniques. We here extend our previous analysis of stellar convective blueshift and its dependence on magnetic activity to a larger sample of stars in order to extend the Teff range, to study the impact of other stellar properties, and finally to improve the comparison between observed RV jitter and expected RV variations. Methods. We estimate a differential velocity shift for Fe and Ti lines of different depths and derive an absolute convective blueshift using the Sun as a reference for a sample of 360 F7-K4 stars with different properties (age, Teff, metallicity). We confirm the strong variation in convective blueshift with Teff and its dependence on (as shown in the line list in Paper I) activity level. Although we do not observe a significant effect of age or cyclic activity, stars with a higher metallicity tend to have a lower convective blueshift, with a larger effect than expected from numerical simulations. Finally, we estimate that for 71% of the stars in our sample the RV and LogR'HK variations are compatible with the effect of activity on convection, as observed in the solar case, while for the other stars, other sources (such as binarity or companions) must be invoked to explain the large RV variations. We also confirm a relationship between LogR'HK and metallicity, which may affect discussions of the possible relationship between metallicity and exoplanets, as RV surveys are biased toward low LogR'HK and possibly toward high-metallicity stars. We conclude that activity and metallicity strongly affect the small-scale convection levels in stars in the F7-K4 range, with a lower amplitude for the lower mass stars and a larger amplitude for low-metallicity stars. Description: List of stars studied in the paper (HARPS data from the ESO archive), together with informations from various sources and outputs from our analysis. The number of stars is 360. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea1.dat 107 360 List of stars studied in the paper
See also: J/A+A/597/A52 : K and G dwarfs stellar granulation variability (Meunier+, 2017) Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Name Star name 13- 16 I4 K Teff Teff 19 I1 --- r_Teff Reference for Teff (1) 22- 23 A2 --- SpType Spectral type from the CDS 26- 29 F4.2 --- B-V B-V from the CDS 33- 36 I4 --- Nsp Number of spectra used in the analysis 39- 45 F7.1 --- TSS Slope of the radial velocity versus line intensity in m/s/(F/Fc) unit (2) 49- 53 F5.1 --- e_TSS 1-sigma uncertainty on TSS in m/s/(F/Fc) 56- 61 F6.3 --- logR'HK Averaged Mount Wilson logR'HK index 65- 69 F5.3 --- e_logR'HK 1-sigma uncertainty on logR'HK 73- 78 F6.1 m/s ConvBL Convective blueshift (3) 81- 85 F5.2 Gyr Age Age 87- 88 I2 --- r_Age ? Reference for the age (1) 90- 92 F3.1 km/s vsini ? Rotational velocity 94- 95 I2 --- r_vsini ? Reference for the vsini (1) 98-107 A10 --- Source Survey including the star (1)
Note (1): References as follows: 1 = Sousa et al., 2008A&A...487..373S 2 = Ramirez et al., 2014A&A...572A..48R 3 = Marsden et al., 2014MNRAS.444.3517M 4 = Datson et al., 2014MNRAS.439.1028D 5 = Borgniet et al., 2017, to be submitted 6 = Lagrange et al. 2013A&A...559A..83L 7 = Gray et al., 2015AJ....150..203G 8 = Gray et al. 2006AJ....132..161G 9 = Allende Prieto & Lambert, 1999A&A...352..555A 10 = Holmberg et al., 2009A&A...501..941H 11 = Delgado Mena et al., 2015A&A...576A..69D 12 = Borgniet et al., 2015, PhD Thesis 13 = Nordstrom et al., 2004A&A...418..989N 14 = Jenkins et al. 2011A&A...531A...8J 15 = Valenti & Fischer, 2005ApJS..159..141V 16 = Dos Santos et al., 2016A&A...592A.156D 17 = Strassmeier et al., 2000A&AS..142..275S 18 = Lovis et al., 2005A&A...437.1121L Note (2): Definition of the TSS: Slope of the radial velocity versus line intensity, where the radial velocity and intensity are computed at the bottom of each line. F/Fc represent the relative flux (i.e. flux divided by the continuum flux) Note (3): Convective blueshift is derived from the TSS in Section 4.1
Acknowledgements: Nadege Meunier, nadege.meunier(at)univ-grenoble-alpes.fr References: Meunier et al., Paper I 2017A&A...597A..52M, Cat. J/A+A/597/A52
(End) Patricia Vannier [CDS] 07-Sep-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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