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 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:
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FileName Lrecl Records Explanations
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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)
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See also:
J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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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
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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.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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)
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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.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 04-May-2018