J/ApJ/858/55 K2 ultracool dwarfs survey. III. M6-L0 flares (Paudel+, 2018)
K2 ultracool dwarfs survey.
III. White light flares are ubiquitous in M6-L0 dwarfs.
Paudel R.R., Gizis J.E., Mullan D.J., Schmidt S.J., Burgasser A.J.,
Williams P.K.G., Berger E.
<Astrophys. J., 858, 55 (2018)>
=2018ApJ...858...55P 2018ApJ...858...55P
ADC_Keywords: Stars, flare; Stars, L-type; Stars, distances; Stars, brown dwarf
Keywords: stars: activity ; stars: flare ;
stars: individual (2MASS J12321827-0951502, TRAPPIST-1)
Abstract:
We report the white light flare rates for 10 ultracool dwarfs using
Kepler K2 short-cadence data. Among our sample stars, two have
spectral type M6, three are M7, three are M8, and two are L0. Most of
our targets are old low-mass stars. We identify a total of 283 flares
in all of the stars in our sample, with Kepler energies in the range
log EKp~(29-33.5)erg. Using the maximum-likelihood method of line
fitting, we find that the flare frequency distribution (FFD) for each
star in our sample follows a power law with slope -α in the
range -(1.3-2.0). We find that cooler objects tend to have shallower
slopes. For some of our targets, the FFD follows either a broken power
law, or a power law with an exponential cutoff. For the L0 dwarf
2MASSJ12321827-0951502, we find a very shallow slope (-α=-1.3)
in the Kepler energy range (0.82-130)x1030erg: this L0 dwarf has
flare rates which are comparable to those of high-energy flares in
stars of earlier spectral types. In addition, we report photometry of
two superflares: one on the L0 dwarf 2MASS J12321827-0951502 and
another on the M7 dwarf 2MASS J08352366+1029318. In the case of
2MASSJ12321827-0951502, we report a flare brightening by a factor of
∼144 relative to the quiescent photospheric level. Likewise, for
2MASSJ08352366+1029318, we report a flare brightening by a factor of
∼60 relative to the quiescent photospheric level. These two
superflares have bolometric (ultraviolet/optical/infrared) energies
3.6x1033erg and 8.9x1033erg respectively, while the full width
half maximum timescales are very short, ∼2min. We find that the M8
star TRAPPIST-1 is more active than the M8.5 dwarf 2M03264453+1919309,
but less active than another M8 dwarf (2M12215066-0843197).
Description:
All the 10 targets listed in Table 1 were observed by Kepler K2 in
various campaigns (see the campaign number in Table 1) in both
long-cadence mode (∼30 min) and short-cadence mode (∼1 min). We used
short-cadence data to study white light flares (WLFs) on all of our
targets.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 87 10 Target properties
table2.dat 23 10 Median flux of targets
table3.dat 32 283 Flare properties
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/ApJ/564/421 : Spectra of T dwarfs. I. (Burgasser+, 2002)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/AJ/139/1808 : Colors and kinematics of SDSS L dwarfs (Schmidt+, 2010)
J/AJ/141/50 : White-light flares on cool Kepler stars (Walkowicz+, 2011)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)
J/ApJ/754/4 : HST monitoring of flaring stars in the bulge (Osten+, 2012)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/MNRAS/428/2824 : Rapid optical variability in ultracool dwarfs (Koen, 2013)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/ApJ/798/73 : BANYAN All-Sky Survey (BASS) catalog. V. YMGs (Gagne+, 2015)
J/AJ/149/158 : The BUD sample. I. L dwarf activity sample (Schmidt+, 2015)
J/ApJS/224/37 : White-light flares on close bin. from Kepler (Gao+, 2016)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/ApJ/817/112 : NEOWISE/AllWISE high PM objects (Schneider+, 2016)
J/AJ/152/24 : Trigonometric plx of 134 low-mass stars (Weinberger+, 2016)
J/ApJ/849/36 : Flaring activity of M dwarfs in Kepler field (Yang+, 2017)
J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Name 2MASS name
25- 34 A10 --- OName Other name
36- 44 I9 --- EPIC [200164267/228754562] EPIC number (1)
46- 50 F5.2 mag Kpmag [14.6/19] Kepler magnitude
52- 56 F5.2 mag Jmag [10.7/13.8] J-band magnitude
58- 59 I2 --- Cam [3/12] K2 campaign number in which the
target was observed
61- 64 F4.1 km/s Vtan [5/61] Tangential velocity Vtan (2)
66- 69 A4 --- SpT MK optical spectral type
71- 75 F5.2 pc Dist [11.2/34] Distance (d)
77- 80 F4.2 pc e_Dist [0.4/6.3] Dist uncertainty
82- 85 A4 --- f_Dist Flag on Dist (3)
87 I1 --- Ref [1/6] Reference used to identify
the spectral types (4)
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Note (1): EPIC 200164267 is not part of the K2 EPIC catalog (Huber+, IV/34).
However it is the same object as EPIC 246199087
(http://archive.stsci.edu/k2/trappist1/); note added by CDS.
Note (2): Vtan was calculated using the relation Vtan=4.74dµ where
d (in parsecs) is the distance of each target and µ is the proper motion.
Note (3): Flag as follows:
a = Distance taken from Henry et al. (2004AJ....128.2460H 2004AJ....128.2460H).
b = Distance taken from Gillon et al. (2016Natur.533..221G 2016Natur.533..221G).
mjst = Distance estimated using a combination of 2MASS J and spectral type
based on the MJ/ST relationship from Dupuy & Liu (2012, J/ApJS/201/19).
miiz = Distance estimated using a combination i-z color based on the i-z/Mi
relationship from S. J. Schmidt et al. (2018, in preparation).
Note (4): Reference as follows:
1 = Giampapa & Liebert (1986ApJ...305..784G 1986ApJ...305..784G)
2 = Cruz et al. (2003, J/AJ/126/2421)
3 = Burgasser et al. (2002, J/ApJ/564/421)
4 = Faherty et al. (2009, J/AJ/137/1)
5 = Gillon et al. (2016Natur.533..221G 2016Natur.533..221G)
6 = Reid et al. (2008, J/AJ/136/1290)
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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- 11 A11 --- AName Abbreviated name
13- 17 I5 ct/s MedFlux2 [358/16463] Median count rate
within 2 pixel radius aperture
19- 23 I5 ct/s MedFlux3 [381/18063] Median count rate
within 3 pixel radius aperture
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- EPIC [200164267/228754562] Kepler identifier
11- 19 F9.4 d PTime [2144.8/2982] Peak flux time during flare,
Barycentric Julian Date; JD-2454833
21- 27 E7.1 s Dur [0.6/41000] Equivalent duration of flare
29- 32 F4.1 [10-7J] logE [29.3/33.5] log of Kepler energy of flare;
in units of ergs.
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History:
From electronic version of the journal
References:
Gizis et al. Paper I. 2017ApJ...838...22G 2017ApJ...838...22G
Gizis et al. Paper II. 2017ApJ...845...33G 2017ApJ...845...33G
Paudel et al. Paper III. 2018ApJ...858...55P 2018ApJ...858...55P This catalog
Paudel et al. Paper IV. 2018ApJ...861...76P 2018ApJ...861...76P
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Mar-2019