J/MNRAS/463/1844 M dwarfs rotation-activity relation (Stelzer+, 2016)
A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data. Stelzer B., Damasso M., Scholz A., Matt S.P. <Mon. Not. R. Astron. Soc., 463, 1844-1864 (2016)> =2016MNRAS.463.1844S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, late-type ; Photometry ; Stars, masses ; Stars, distances ; Effective temperatures Keywords: stars: activity - stars: flare - stars: late-type - stars: rotation - ultraviolet: stars . X-rays: stars Abstract: We study the relation between stellar rotation and magnetic activity for a sample of 134 bright, nearby M dwarfs observed in the Kepler Two-Wheel (K2) mission during campaigns C0 to C4. The K2 lightcurves yield photometrically derived rotation periods for 97 stars (79 of which without previous period measurement), as well as various measures for activity related to cool spots and flares. We find a clear difference between fast and slow rotators with a dividing line at a period of ∼10d at which the activity level changes abruptly. All photometric diagnostics of activity (spot cycle amplitude, flare peak amplitude and residual variability after subtraction of spot and flare variations) display the same dichotomy, pointing to a quick transition between a high-activity mode for fast rotators and a low-activity mode for slow rotators. This unexplained behavior is reminiscent of a dynamo mode-change seen in numerical simulations that separates a dipolar from a multipolar regime. A substantial number of the fast rotators are visual binaries. A tentative explanation is accelerated disk evolution in binaries leading to higher initial rotation rates on the main-sequence and associated longer spin-down and activity lifetimes. We combine the K2 rotation periods with archival X-ray and UV data. X-ray, FUV and NUV detections are found for 26, 41, and 11 stars from our sample, respectively. Separating the fast from the slow rotators, we determine for the first time the X-ray saturation level separately for early- and for mid-M stars. Description: This work is based on all bright and nearby M dwarfs from the Superblink proper motion catalog by Lepine & Gaidos (2011, Cat. J/AJ/142/138) observed within the K2 mission's campaigns C0-C4. A total of 134 Superblink M dwarfs have been observed in K2 campaigns C0-C4. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 114 134 Target list for K2 Campaign C0-C4 with stellar parameters table2.dat 43 133 Rotation and activity parameters derived from the K2 light curves (all target but 206262223)
See also: J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 9 I9 --- EPIC EPIC identification number 11- 13 A3 --- n_EPIC [*Ba ] Note on EPIC (1) 15- 16 A2 --- Campaign Campaign (C0-C4) 18- 27 A10 --- CNS-name CNS name (Gliese & Jahreiss, 1991, Cat. V/70) 29- 33 F5.2 mag Kpmag Kepler magnitude 35- 39 F5.2 mag Vmag V magnitude 41- 44 F4.2 mag e_Vmag rms uncertainty on Vmag 46- 49 F4.2 mag Jmag J magnitude 51- 54 F4.2 mag e_Jmag rms uncertainty on Jmag 56- 59 F4.2 mag Ksmag Ks magnitude 61- 64 F4.2 mag e_Ksmag rms uncertainty on Ksmag 66- 69 F4.1 pc Dist Distance 71- 74 F4.2 Msun Mass Stellar mass 76- 79 F4.2 Msun e_Mass rms uncertainty on stellar mass 81- 84 F4.2 Rsun Rad Stellar radius 86- 89 F4.2 Rsun e_Rad rms uncertainty on Stellar radius 91- 95 F5.2 [Lsun] logLbol Bolometric luminosity 97-100 F4.2 [Lsun] e_logLbol rms uncertainty on bolometric luminosity 102-105 I4 K Teff Effective temperature 107-109 I3 K e_Teff rms uncertainty on Teff 111-114 A4 --- SpType Spectral type
Note (1): Notes as follows: B = Potential contamination by companion star in binary (see Appendix B). * = MKs slightly outside the range of calibrated values (see the text in Section 3). a = This star (Gl 852B) is not considered further because we assign the rotation and activity to the primary (Gl 852A) in the unresolved binary.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 9 I9 --- EPIC EPIC identification number 11- 16 F6.2 d Prot ?=- Rotational period 18- 21 A4 --- Method Method used 23 A1 --- Flag [YN?] Flag (1) 25- 28 F4.2 --- R0 ?=- Rossby number (2) 30- 35 F6.3 % Rper Rper parameter (3) 37- 43 F7.1 ppm Sph Sph parameter (3)
Note (1): Flag as follows: Y = reliable period ? = questionable period detection N = no period Note (2): defined as R0=Prot/τconv, where τconv is the convective turnover time. Note (3): parameters Rper and Sph are measures for the variability in the K2 light curve.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 04-May-2018
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