J/ApJ/912/81 Kepler and XMM LCs of 3 KIC stars with flares (Kuznetsov+, 2021)
Stellar superflares observed simultaneously with Kepler and XMM-Newton.
Kuznetsov A.A., Kolotkov D.Y.
<Astrophys. J., 912, 81 (2021)>
=2021ApJ...912...81K 2021ApJ...912...81K
ADC_Keywords: Stars, flare; X-ray sources; Photometry, UBVRI; Stars, M-type;
Abundances, [Fe/H]; Stars, masses; Stars, diameters
Keywords: Optical flares ; Stellar x-ray flares ; Markov chain Monte Carlo
Abstract:
Solar and stellar flares are powerful events that produce intense
radiation across the electromagnetic spectrum. Multiwavelength
observations are highly important for understanding the nature of
flares, because different flare-related processes reveal themselves in
different spectral ranges. To study the correlation between thermal
and nonthermal processes in stellar flares, we have searched the
databases of Kepler (optical observations) and XMM-Newton (soft
X-rays) for the flares observed simultaneously with both instruments;
nine distinctive flares (with energies exceeding 1033erg) on three
stars (of K-M spectral classes) have been found. We have analyzed and
compared the flare parameters in the optical and X-ray spectral
ranges; we have also compared the obtained results with similar
observations of solar flares. Most of the studied stellar flares
released more energy in the optical range than in X-rays. In one
flare, X-ray emission strongly dominated, which could be caused either
by a soft spectrum of energetic electrons or by a near-limb position
of this flare. The X-ray flares were typically delayed with respect to
and shorter than their optical counterparts, which is partially
consistent with the Neupert effect. Using the scaling laws based on
the magnetic reconnection theory, we have estimated the characteristic
magnetic field strengths in the stellar active regions and the sizes
of these active regions as about 25-70G and 250000-500000km,
respectively. The observed stellar superflares appear to be scaled-up
versions of solar flares, with a similar underlying mechanism and
nearly the same characteristic magnetic field values, but with much
larger active region sizes.
Description:
Simultaneous Kepler and XMM-Newton observations of superflares on the
young Pleiades stars during the Kepler/K2 mission have been studied
earlier by Guarcello+ (2019A&A...622A.210G 2019A&A...622A.210G and 2019AN....340..302G 2019AN....340..302G);
in contrast, we consider here the primary Kepler observational
campaign (2009 May-2013 May).
Simultaneous Kepler and XMM-Newton observations during the primary
Kepler campaign have been studied before by
Pizzocaro+ (2019, J/A+A/628/A41); see Section 2.1.
As the starting point for the X-ray data, we used the 3XMM-DR5
serendipitous source catalog (Rosen+ 2016, IX/46 superseded by IX/50).
The Kepler data archive provides nearly continuous light curves for
hundreds of thousands of stars within its field of view.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 211 3 Parameters of the selected KIC stars
fig2.dat 39 253 Light curves of KIC 8093473
fig3.dat 39 115 Light curves of KIC 8454353
fig4.dat 39 157 Light curves of KIC 9048551
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See also:
B/xmm : XMM-Newton Observation Log (XMM-Newton Science Operation Center, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
IX/46 : XMM-Newton Serendipitous Source Catalogue 3XMM-DR5 (XMM-SSC, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/A+A/534/A133 : Proxima Cen chromospheric em. lines (Fuhrmeister+, 2011)
J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/A+A/583/A65 : Active Kepler stars differential rotation (Reinhold+, 2015)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/MNRAS/457/2877 : Kepler M dwarf stars revised properties (Gaidos+, 2016)
J/ApJ/851/91 : Stat. studies of solar white-light flares (Namekata+, 2017)
J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)
J/A+A/620/A55 : Magnetic flaring from PMS stars spectra (Flaccomio+, 2018)
J/ApJ/883/88 : Short-duration flares from GALEX & Kepler (Brasseur+, 2019)
J/A+A/628/A41 : KIC stars in Kepler/XMM-Newton (Pizzocaro+, 2019)
J/ApJ/871/174 : Kepler rapid rotators and Ks-band excesses (Simonian+, 2019)
J/AJ/157/216 : Stellar mult. rate of M dwarfs within 25pc (Winters+, 2019)
http://archive.stsci.edu/missions-and-data/kepler : Kepler home page on MAST
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [KIC]
5- 11 I7 --- KIC KIC number
13- 14 A2 --- SpT Spectral type (1)
16- 19 I4 K Teff [3357/4124] Gaia DR2 (I/345) effective
temperature
21- 24 I4 K b_Teff [3344/4025] Teff lower limit
26- 29 I4 K B_Teff [3528/4138] Teff upper limit
31- 35 F5.3 Lsun Lum [0.05/0.12] Gaia DR2 luminosity
37- 41 F5.3 Lsun b_Lum [0.05/0.11] Lum lower limit
43- 47 F5.3 Lsun B_Lum [0.05/0.12] Lum upper limit
49- 53 F5.1 pc Dist [125/206] Gaia DR2 distance
55- 59 F5.1 pc b_Dist [125/199] Dist lower limit
61- 65 F5.1 pc B_Dist [126/214] Dist upper limit
67- 71 F5.2 [-] [Fe/H] [-0.16/0.04] Metallicity
73- 77 F5.2 [-] b_[Fe/H] [-0.27/-0.05] [Fe/H] lower limit
79- 83 F5.2 [-] B_[Fe/H] [-0.05/0.14] [Fe/H] upper limit
85 A1 --- r_[Fe/H] Flag on [Fe/H] (2)
87- 91 F5.3 d Prot [1.49/8.56] Rotational period from
McQuillan+ 2014, J/ApJS/211/24
93- 97 F5.3 mag Av [0.08/0.18] Optical extinction, AV, from
Brown+ 2011, J/AJ/142/112
99- 104 F6.3 mag Bmag [15.34/17.3] Johnson B magnitude (3)
106- 111 F6.3 mag Vmag [14.08/16.01] Johnson V magnitude (3)
113- 118 F6.3 mag Ksmag [10.46/11.56] 2MASS (II/246) Ks-band magnitude
120- 125 F6.3 mag b_Ksmag [10.44/11.54] Ksmag lower limit
127- 132 F6.3 mag B_Ksmag [10.48/11.58] Ksmag upper limit
134- 139 F6.3 mag Gmag [13.33/14.95] Gaia DR2 G-band magnitude
141- 146 F6.3 mag b_Gmag [13.33/14.94] Gmag lower limit
148- 153 F6.3 mag B_Gmag [13.33/14.95] Gmag upper limit
155- 160 F6.3 mag BPmag [14.18/16.1] Gaia DR2 BP-band magnitude
162- 167 F6.3 mag b_BPmag [14.18/16.09] BPmag lower limit
169- 174 F6.3 mag B_BPmag [14.19/16.11] BPmag upper limit
176- 181 F6.3 mag RPmag [12.43/13.87] Gaia DR2 RP-band magnitude
183- 188 F6.3 mag b_RPmag [12.43/13.86] RPmag lower limit
190- 195 F6.3 mag B_RPmag [12.44/13.87] RPmag upper limit
197- 200 F4.2 Msun Mass [0.4/0.6]? Estimated component mass (4)
202- 205 F4.2 Rsun Rad [0.4/0.55]? Radius (4)
207- 211 F5.3 AU a [0.02/0.07]? Orbital separation (4)
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Note (1): Spectral types were estimated from the effective temperatures
according to Pecaut & Mamajek (2013, J/ApJS/208/9).
Note (2): Reference code as follows:
c = Gaidos+ 2016, J/MNRAS/457/2877
d = APOGEE (Jonsson+ 2020, III/284)
Note (3): From Pizzocaro+ 2019, J/A+A/628/A41
Note (4): We present the estimated component masses (Mstar) and
radii (Rstar) as well as orbital separations (a) for the supposed
binaries (see Section 4.3).
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Byte-by-byte Description of file: fig[234].dat
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Bytes Format Units Label Explanations
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1 A1 --- Tel Telescope; (K)epler or (X)MM/PN
3- 19 F17.11 d MJD [55164.7/55830.2] Modified Julian Date
21- 31 F11.5 --- Flux [0.0005/54963] Flux (1)
33- 39 F7.5 --- e_Flux [0.002/7.5] Uncertainty in Flux (2)
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Note (1): The Kepler fluxes and uncertainties are in Kepler units.
The XMM PN fluxes and uncertainties are in counts/s.
Note (2): The XMM flux uncertainty includes both the target and
background flux uncertainties.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Oct-2022