J/ApJ/849/36 Flaring activity of M dwarfs in the Kepler field (Yang+, 2017)
The flaring activity of M dwarfs in the Kepler field. Yang H., Liu J., Gao Q., Fang X., Guo J., Zhang Y., Hou Y., Wang Y., Cao Z. <Astrophys. J., 849, 36 (2017)> =2017ApJ...849...36Y
ADC_Keywords: Stars, flare; Stars, M-type; Stars, dwarfs Keywords: stars: activity; stars: flare; stars: late-type; stars: statistics; starspots Abstract: Flare events are mainly due to magnetic reconnection and thus are indicative of stellar activity. The Kepler Space Observatory records numerous stellar activities with unprecedented high photometric precision in flux measurements. It is perfectly suitable for carrying out a statistical study of flares. Here we present 540 M dwarfs with flare events discovered using Kepler long-cadence data. The normalized flare energy, as defined by the ratio to bolometric stellar luminosity, Lflare/Lbol, is used to indicate the flare activity. We find that, similar to the X-ray luminosity relation, the Lflare/Lbol versus Prot relation can also be described with three phases, supersaturation, saturation, and exponential decay, corresponding to an ultra- short period, a short period, and a long period. The flare activity and the number fraction of flaring stars in M dwarfs rise steeply near M4, which is consistent with the prediction of a turbulent dynamo. The size of starspots are positively correlated with flare activity. The Lflare/Lbol ratio has a power-law dependence on LHα/Lbol, a parameter indicative of stellar chromosphere activity. According to this relation, a small enhancement in chromosphere activity may cause a huge rise in flare energy, which suggests that superflares or hyperflares may not need an extra excitation mechanism. Through a comparison study, we suggest that flare activity is a more suitable indicator for stellar activity, especially in the boundary region. However, contrary to what is expected, some M dwarfs with strong flares do not show any light variation caused by starspots. Follow-up observations are needed to investigate this problem. Description: Our work is based on the entire Kepler mission long-cadence data set (Q1-Q17; 48 months (May 2009 - Apr 2013); Data Release 25). In order to make spectroscopic studies of our targets, we also used the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) for the observations. The spectral resolution of LAMOST is R∼1800 and wavelength coverage is ∼3700-9000Å. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 81 540 Parameters of flaring M dwarfs table3.dat 48 103178 Flare parameters
See also: III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997) V/149 : LAMOST DR2 catalogs (Luo+, 2016) V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003) J/AJ/128/426 : Subdwarfs in the SDSS (West+, 2004) J/MNRAS/390/545 : Magnetic field & velocity of early M dwarfs (Donati+, 2008) J/MNRAS/390/567 : Magnetic field and velocity of mid M dwarfs (Morin+, 2008) J/MNRAS/407/465 : Fast-rotating M dwarfs in NGC2516 (Jackson+, 2010) J/AJ/142/112 : KIC photometric calibration (Brown+, 2011) J/MNRAS/411/2099 : Fast-rotating M-dwarf stars in NGC 2547 (Jeffries+, 2011) J/AJ/141/50 : White-light flares on Kepler cool stars (Walkowicz+, 2011) J/ApJ/743/48 : Stellar rot. periods & X-ray luminosities (Wright+, 2011) J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012) J/ApJ/754/4 : HST obs. of flaring stars in the Gal. bulge (Osten+, 2012) J/AJ/143/93 : Rotational velocities in early-M stars (Reiners+, 2012) J/ApJS/204/24 : Kepler planetary candidates. III. (Batalha+, 2013) J/ApJ/767/95 : Improved parameters of smallest KIC stars (Dressing+, 2013) J/ApJ/771/107 : Spectroscopy of faint KOI stars (Everett+, 2013) J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013) J/A+A/560/A4 : Rotation periods of active Kepler stars (Reinhold+, 2013) J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013) J/ApJ/795/161 : Activity & rotation in Praesepe & Hyades (Douglas+, 2014) J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014) J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014) J/MNRAS/447/2714 : Flare stars across the H-R diagram (Balona+, 2015) J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015) J/ApJ/801/3 : Rotation periods for Q3-Q14 KOIs (Mazeh+, 2015) J/ApJ/812/3 : MEarth mid-to-late M dwarfs kinematics (West+, 2015) J/A+A/589/A113 : PMS stars in h Per (Argiroffi+, 2016) J/AJ/151/68 : Kepler Mission. VII. Eclipsing binaries in DR3 (Kirk+, 2016) J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016) J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016) J/ApJS/224/37 : White-light flares on Kepler close binaries (Gao+, 2016) http://exoplanetarchive.ipac.caltech.edu/ : NASA exoplanet archive Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 I8 --- KIC [892376/12835232] Kepler Input Catalog identifier 10- 16 F7.2 d Date [31.7/1415.3] Kepler observation time 18- 21 I4 --- FNum [8/1184] Number of flares 23- 28 F6.3 d Per [0.2/68.3]?=-1 Rotation period 30- 38 A9 --- r_Per Reference for Per (1) 40- 44 I5 ppm Amp [200/85660] Amplitude of lightcurve from starspots (2) 46- 55 A10 --- Ha Hα line description (absorption, emission or "no data"=480 occurrences) 57- 70 E14.7 --- HaLum [1.5e-05/0.00025]?=-1 Normalized Hα activity luminosity (3) 72- 81 E10.4 --- FLum [3.2e-08/0.00034] Flare activity luminosity (3)
Note (1): Reference as follows: Mc2014 = McQuillan+ (2014, J/ApJS/211/24 ; 392 occurrences); Rein2013 = Reinhold+ (2013, J/A+A/560/A4 ; 29 occurrences); This work = Yang+, 2017ApJ...849...36Y : this work (91 occurrences); No period = No period value (28 occurrences). Note (2): There are 29 flaring stars without apparent rotation periods, and their upper limits of variation amplitude were calculated using the noise of lightcurves. Note (3): Relative to the bolometric luminosity.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 8 I8 --- KIC [892376/12835232] Kepler Input Catalog identifier 10- 17 F8.3 d St-BKJD [131.5/1591] Kepler Barycentric Julian Date start; BJD-2454833 19- 26 F8.3 d Ed-BKJD [131.5/1591] Kepler Barycentric Julian Date end; BJD-2454833 28- 34 F7.4 [10-7J] logEng [29.7/35.9] log flare energy 36- 48 E13.7 --- Area [2.6e-07/0.0041] Flare area relative to stellar surface area
Acknowledgments: Huiqin Yang [National Astronomical Observatories of China] History: From electronic version of the journal There are 103187 lines in the original version of Table 3 but data for KIC 8421129 have been removed at CDS because this target was excluded by the pollution check.
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Jun-2018
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