J/AJ/162/11 EDEN project: Flare activity of nearby M-dwarf Wolf 359 (Lin+, 2021)
EDEN: flare activity of the nearby exoplanet-hosting M dwarf Wolf 359 based on
K2 and EDEN light curves.
Lin C.-L., Chen W.-P., Ip W.-H., Apai D., Bixel A., Boyle R., Chavez J.P.,
Espinoza N., Gibbs A., Gabor P., Henning T., Mancini L., Rackham B.V.,
Schlecker M., Dietrich J., Socia Q.J., Keppler M., Bhandare A., Haberle M.
<Astron. J., 162, 11-11 (2021)>
=2021AJ....162...11L 2021AJ....162...11L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs; Exoplanets; Stars, flare; Optical
Keywords: Planet hosting stars; Exoplanet systems; Exoplanet astronomy
Exoplanets; Flare stars; Stellar flares; Stellar phenomena
Abstract:
We report the flare activity of Wolf359, the fifth closest star to the
Sun and a candidate exoplanet-hosting M-dwarf. The star was a target
of the Kepler/K2 mission and was observed by the EDEN project, a
global network of 1-2m class telescopes for detection and
characterization of rocky exoplanets in the habitable zones of late
M-dwarfs within 50 light year from the solar system. In the
combination of the archived K2 data and our EDEN observations, a total
of 872 flares have been detected, 861 with the K2 (860 in the
short-cadence and 18 in the long-cadence data, with 17 long-cadence
events having short-cadence counterparts) and 11 with EDEN. Wolf 359
has relatively strong flare activity even among flaring M-dwarfs, in
terms of the flare activity indicator (FA) defined as the integrated
flare energy relative to the total stellar bolometric energy, where
FA=∑Ef/∫Lboldt∼8.93x10-5 for the long-cadence flares,
whereas for K2 short cadence and EDEN flares, the FA values are
somewhat larger, FA∼6.67 x 10-4 and FA∼5.25x10-4, respectively.
Such a level of activity, in accordance with the rotation period
(Prot), suggests the star to be in the saturation phase. The size of
the starspots is estimated to be at least 1.87%±0.59% of the
projected disk area of Wolf359. We find no correlation of FA with the
stellar rotational phase. Our analysis indicates a flare frequency
distribution in a power-law form of dN/dE∝E-α with
α=2.13±0.14, equivalent to an occurrence rate of flares
Ef≳1031erg about once per day and of superflares with
Ef≳1033erg approximately 10 times per year. These superflares may
impact the habitability of system in multiple ways, the details of
which are topics for future investigations.
Description:
Wolf359 was observed by the Kepler space telescope in Campaign 14 of
the K2 mission from 2017 June 1 to 2017 August 19.
Wolf 359 is also one of the red dwarf targets of interest to the
ExoEarth Discovery and Exploration Network (EDEN) project. The
partnership of EDEN includes the Department of Physics of the
University of Rome "Tor Vergata"; the Steward Observatory of the
University of Arizona; the Max-Planck-Institut fur Astronomie,
Germany; the Vatican Observatory; and the Lulin Observatory of
National Central University, Taiwan (EDEN PIs are: D. Apai, P. Gabor,
Th. Henning, and W-P. Chen). There were three separate observing
sessions of Wolf359, one contributed by the Vatican Advanced
Technology Telescope (VATT) 1.83m telescope in the V band on 2019
January 30 and the other two by the Kuiper 1.54m telescope in the R
band on 2019 February 25 and 27. The total observation time was 16hr
with cadences of 30-45s.
Objects:
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RA (2000) DE Designation(s) (Period)
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10 56 28.92 +07 00 53.0 Wolf 359 = Wolf 359 (P=2.72)
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 109 11 The flares observed on Wolf 359 by EDEN in this
study
table3.dat 153 18 The K2LC flares and their short cadence
counterparts
table4.dat 98 860 Flares detected by K2 short cadence
observations of Wolf 359
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See also:
J/AJ/140/1402 : M dwarf flares from SDSS spectra (Hilton+, 2010)
J/ApJ/754/4 : HST monitoring of flaring stars in Galactic bulge (Osten+, 2012)
J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)
J/MNRAS/445/2268 : Bayesian method for detecting stellar flares (Pitkin+, 2014)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)
J/ApJ/883/88 : Short-duration stellar flares GALEX & Kepler (Brasseur+, 2019)
J/ApJ/890/46 : Superflares on solar-type stars from TESS first year (Tu+, 2020)
J/MNRAS/505/L79 : Characteristic time of stellar flares (Yan+, 2021)
J/other/CoSka/51.78 : Flare stars nearby Galactic open clusters (Maryeva+ 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Flare [0/10] Flare number
4- 21 F18.16 --- Af [0.01/0.32] Flare peak amplitude
23- 44 E22.15 10-7J Efl Flare energy in used band, ergs
46- 67 E22.15 10-7J Ef Bolometric flare energy, ergs
69- 86 F18.13 d BJD [3681/3710] Time of flare peak; BJD-2454833
88-107 F20.18 h Dur [0.03/0.23] Duration of flare
109-109 A1 --- Flag [VR] Bandpass flag
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Flare [0/17] Flare number
4- 11 F8.6 --- AfLC [0.004/0.16] K2LC flare peak amplitude,
13- 20 A8 10-7J EflLC K2LC flare energy Kepler band, ergs
22- 43 A22 10-7J EfLC K2LC bolometric flare energy, ergs
45- 55 F11.6 d BJDLC [3078/3148] K2LC time of flare peak, BJD-2454833
57- 62 F6.3 h DurLC [1.47/21.1] K2LC duration of flare
64- 81 F18.16 --- AfSC [0.01/0.29]? K2SC flare peak amplitude
83-104 A22 10-7J EflSC K2SC flare energy Kepler band, ergs
106-127 A22 10-7J EfSC K2SC bolometric flare energy, ergs
129-146 F18.13 d BJDSC [3078/3148]? K2SC time of flare peak, BJD-2454833
148-153 F6.3 h DurSC [0.85/19]? K2SC duration of flare
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Flare [0/859] flare number
5- 22 F18.16 --- Af [0.002/1.93] flare peak amplitude
24- 45 A22 10-7J Efl Flare energy in the used band, λ, ergs
47- 68 A22 10-7J Ef Bolometric flare energy, ergs
70- 87 F18.13 d BJD [3072/3153] Time of flare peak, BJD-2454833
89- 94 F6.3 h Dur [0.04/18.9] duration of flare
96- 98 A3 -- Flag Flare observed in LC data? Yes or No
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 04-Nov-2021