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J/A+A/600/A13   HARPS M dwarf sample magnetic activity  (Astudillo-Defru+, 2017)

Magnetic activity in the HARPS M dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK. Astudillo-Defru N., Delfosse X., Bonfils X., Forveille T., Lovis C., Rameau J. <Astron. Astrophys. 600, A13 (2017)> =2017A&A...600A..13A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, dwarfs ; Stars, masses ; Spectroscopy Keywords: stars: activity - stars: late-type - stars: rotation - stars: planetary systems - techniques: spectroscopic Abstract: Atmospheric magnetic fields in stars with convective envelopes heat stellar chromospheres, and thus increase the observed flux in the CaII H and K doublet. Starting with the historical Mount Wilson monitoring program, these two spectral lines have been widely used to trace stellar magnetic activity, and as a proxy for rotation period (Prot) and consequently for stellar age. Monitoring stellar activity has also become essential in filtering out false-positives due to magnetic activity in extra-solar planet surveys. The CaII emission is traditionally quantified through the R'HK-index, which compares the chromospheric flux in the doublet to the overall bolometric flux of the star. Much work has been done to characterize this index for FGK-dwarfs, but M dwarfs - the most numerous stars of the Galaxy - were left out of these analyses and no calibration of their CaII H and K emission to an R'HK exists to date. We set out to characterize the magnetic activity of the low- and very-low-mass stars by providing a calibration of the R'HK-index that extends to the realm of M dwarfs, and by evaluating the relationship between R'HK and the rotation period.. We calibrated the bolometric and photospheric factors for M dwarfs to properly transform the S-index (which compares the flux in the CaII H and K lines to a close spectral continuum) into the R'HK. We monitored magnetic activity through the CaII H and K emission lines in the HARPS M dwarf sample. Description: R'HK analysis for the HARPS M dwarf sample. Updated relationships for the bolometric factor and photospheric correction are used to transform the CaH&K emission to the R'HK. A relationship is obtained for the R'HK vs. Prot dependence, and used to estimate the stellar rotation for the HARPS M dwarf sample. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea3.dat 87 403 Parameters, activity and rotation periods for the HARPS M dwarf sample
See also: I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007) J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011) J/ApJ/752/56 : BDKP III. Parallaxes for 70 ultracool dwarfs (Faherty+ 2012) J/MNRAS/443/2561 : CONCH-SHELL catalog of nearby M dwarfs (Gaidos+, 2014) Byte-by-byte Description of file: tablea3.dat
Bytes Format Units Label Explanations
1- 9 A9 --- Name Object name 11- 15 F5.2 mag Vmag Visual magnitude 17- 20 F4.2 mag B-V B-V color index 22- 26 F5.3 mag V-K V-K color index 28- 33 F6.2 mas plx Parallax 35- 39 F5.2 mas e_plx Parallax uncertainty 41 I1 --- r_Vmag [1/2] Reference for the photometry (1) 43 I1 --- r_plx [2/7] Reference for the parallax (1) 45- 48 F4.2 Msun Mass Stellar mass 50- 52 I3 --- Nsp Number of spectra used in the analysis 54- 59 F6.3 --- S S-index 61- 65 F5.3 --- e_S S-index uncertainty 67- 72 F6.3 --- log(R'HK) logarithm R'HK-index 74- 78 F5.3 --- e_log(R'HK) R'HK-index uncertainty 80- 82 I3 d Prot Stellar rotation 84- 87 F4.1 --- SNR Average SNR in the violet and red bands
Note (1): References as follows: 1 = Leggett (1992ApJS...82..351L) 2 = Gaidos et al. (2014, Cat. J/MNRAS/443/2561) 3 = van Leeuwen (2007A&A...474..653V, Cat. I/311) 4 = van Altena et al. (1995, Cat. I/238) 5 = RECONS, research consortium on nearby stars parallax program (e.g., Riedel et al. 2010AJ....140..897R; Jao et al. 2011AJ....141..117J). 6 = Lepine & Gaidos (2011, Cat. J/AJ/142/138) 7 = Hawley et al. (1997AJ....113.1458H)
Acknowledgements: Nicola Astudillo-Defru, nicola.astudillo(at)unige.ch
(End) Patricia Vannier CDS 01-Feb-2017
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