J/ApJ/926/204 TESS monitoring campaign of low-mass flare stars (Howard+, 2022)
No such thing as a simple flare: substructure and quasi-periodic pulsations
observed in a statistical sample of 20s cadence TESS flares.
Howard W.S., MacGregor M.A.
<Astrophys. J., 926, 204 (2022)>
=2022ApJ...926..204H 2022ApJ...926..204H
ADC_Keywords: Stars, flare; Stars, masses; Stars, M-type
Keywords: Optical flares ; Flare stars ; M dwarf stars ; Habitable planets ;
Astrobiology
Abstract:
A 20s cadence Transiting Exoplanet Survey Satellite monitoring
campaign of 226 low-mass flare stars during Cycle 3 recorded
3792 stellar flares of ≥1032erg. We explore the time-resolved
emission and substructure in 440 of the largest flares observed at
high signal-to-noise, 97% of which released energies of ≥1033erg.
We discover degeneracy present at 2 minute cadence between sharply
peaked and weakly peaked flares is common, although 20s cadence
breaks these degeneracies. We better resolve the rise phases and find
46% of large flares exhibit substructure during the rise phase. We
observe 49 candidate quasi-periodic pulsations (QPP) and confirm 17 at
≥3σ. Most of our QPPs have periods less than 10 minutes,
suggesting short-period optical QPPs are common. We find QPPs in both
the rise and decay phases of flares, including a rise-phase QPP in a
large flare from Proxima Cen. We confirm that the
Davenport+ (2014ApJ...797..122D 2014ApJ...797..122D) template provides a good fit to most
classical flares observed at high cadence, although 9% favor Gaussian
peaks instead. We characterize the properties of complex flares,
finding 17% of complex flares exhibit "peak-bump" morphologies
composed of a large, highly impulsive peak followed by a second, more
gradual Gaussian peak. We also estimate the UVC surface fluences of
temperate planets at flare peak and find one-third of 1034erg flares
reach the D90 dose of Deinococcus radiodurans in just 20s in the
absence of an atmosphere.
Description:
In its initial and extended missions, the Transiting Exoplanet Survey
Satellite (TESS) has been searching for transiting exoplanets and
astrophysical variability across the entire sky, split into
∼26 sectors. TESS observes each sector continuously with four 10.5cm
optical telescopes in a red (600-1000nm) bandpass for 28 days at
21"/pixel. Calibrated, 20s cadence TESS light curves from TESS Cycle 3
GO 3174 of each sector 27-37 flare star and Proxima Cen were
downloaded from the Mikulski Archive for Space Telescopes (MAST).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 9 146 List of the 146 unique stars extracted from
Tables 1+2; table added by CDS
table1.dat 79 3792 Catalog of all 3792 flares observed across
226 M-dwarfs at 20 second cadence during
TESS Cycle 3
table2.dat 122 440 Time-resolved properties of 440 large flares
observed across 226 M-dwarfs at 20 second cadence
during TESS Cycle 3
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See also:
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
J/AJ/132/866 : New M dwarfs in solar neighborhood (Riaz+, 2006)
J/ApJ/767/95 : Improved parameters of smallest KIC stars (Dressing+, 2013)
J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)
J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)
J/ApJ/807/45 : Habitable planets around M dwarfs (Dressing+, 2015)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (Sullivan+, 2015)
J/ApJ/859/87 : Kepler long- and short-cadence flare parameters (Yang+, 2018)
J/ApJ/883/88 : Short-duration stellar flares (Brasseur+, 2019)
J/MNRAS/489/437 : Origin of stellar flares on M dwarfs with TESS (Doyle+, 2019)
J/ApJ/881/9 : EvryFlare. I. Cool stars's flares (Howard+, 2019)
J/AJ/159/60 : Flares from 1228 stars in TESS sectors 1 & 2 (Gunther+, 2020)
J/ApJ/902/115 : EvryFlare. III. Superflares (Howard+, 2020)
J/ApJ/895/140 : EvryFlare. II. Param. of 122 cool flare stars (Howard+, 2020)
J/ApJ/905/107 : Sp. activity indicators of TIC stars (Medina+, 2020)
J/ApJS/256/33 : Magellan-TESS Survey (MTS). I. (Teske+, 2021)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC [593228/471016669] Identifier, TESS input
catalog
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC [593228/471016669] Identifier, TESS input
catalog
11- 19 F9.4 d TBJD-start [2036.3/2353.4] Flare start time, TESS
Barycentric Julian Date (1)
21- 29 F9.4 d TBJD-peak [2036.3/2353.4] Flare peak time, TESS
Barycentric Julian Date (1)
31- 39 F9.4 d TBJD-stop [2036.3/2353.5] Flare stop time, TESS
Barycentric Julian Date (1)
41- 44 I4 s ED [10/8980] Equivalent duration
46- 49 F4.1 [10-7J] logEbol [32/35.8] Log, flare energy, erg
51- 55 F5.3 --- AT [0.003/6.6] Peak flare amplitude,
measured at 20s cadence (2)
57- 60 I4 --- SNR [3/1137] Photometric S/N of the peak
62- 65 F4.2 Msun Mstar [0.12/0.63] Stellar mass
67- 75 F9.6 d Prot [0.1/83]? Rotational period
77- 79 A3 --- Noisy Photometric scatter too noisy? (3)
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Note (1): TESS Barycentric Julian Date (TBJD), TBJD=BJD-2457000.0
Note (2): in fractional flux units.
Note (3):
yes = the photometric scatter was too noisy to reliably determine
substructure properties.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC [2760232/471016669] Identifier, TESS
input catalog
11- 20 F10.5 d TBJD-start [2037.5/2335.3] Flare start time, TESS
Barycentric Julian Date (1)
22- 31 F10.5 d TBJD-peak [2037.5/2335.3] Flare peak time, TESS
Barycentric Julian Date (1)
33- 42 F10.5 d TBJD-stop [2037.6/2335.3] Flare stop time, TESS
Barycentric Julian Date (1)
44- 47 I4 s ED [50/8980] Equivalent duration
49- 52 F4.1 [10-7J] logEbol [32/35.8] Log, flare energy, erg
54- 58 F5.3 --- AT [0.018/6.6] Peak flare amplitude,
measured at 20s cadence (2)
60- 65 F6.2 min FWHM [0.2/179] FWHM duration in minutes
67- 73 F7.5 --- IMPL [0.00019/4] Impulse (3)
75 I1 --- Nrise [1/5] Number, substructure peaks in the
rise phase
77 I1 --- Ndom [1/6] Number, dominant peaks (4)
79- 80 I2 --- Ntot [1/11] Number of peaks across the
entire flare
82 A1 --- Complex Rise phase complexity is present
84 A1 --- QPP QPPs are present?
86- 89 I4 --- signif [4/1137] Significance
91- 95 F5.3 Msun Mstar [0.12/0.6] Stellar mass
97- 105 F9.6 d Prot [0.12/83]? Rotational period
107- 111 F5.2 [10-7W] logQ0 [28.3/32] Log, quiescent luminosity, erg/s
113- 117 I5 J/m2 HZFluUVC [10/16200] UVC fluence (5)
119- 122 F4.1 --- logFsurv [-4.9/-0] Log, estimated survival
fraction (6)
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Note (1): TESS Barycentric Julian Date (TBJD), TBJD=BJD-2457000.0
Note (2): in fractional flux units.
Note (3): in units of AT/FWHM.
Note (4): the number of dominant peaks that best describe the overall shape
of the light curve.
Note (5): the amount of UVC fluence from the 20 second flare peak reaching
the surface of a habitable zone planet in the absence of a significant
atmosphere.
Note (6): the estimated survival fractions of common micro-organisms after
20 seconds of peak UVC emission.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Nov-2023