J/MNRAS/512/L60 Flare detections of TOI host stars (Howard+, 2022)
The flaring TESS Objects of Interest flare rates for all two-minute cadence
TESS planet candidates.
Howard W.S.
<Mon. Not. R. Astron. Soc. 512, L60-L65 (2022)>
=2022MNRAS.512L..60H 2022MNRAS.512L..60H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, flare ;
Stars, atmospheres ; Transient ; Binaries, orbits ;
Cross identifications ; Positional data ; Photometry ; Optical ;
Stars, distances ; Stars, masses
Keywords: planets and satellites: atmospheres -
planets and satellites: fundamental parameters - stars: flare
Abstract:
Although more than 5000 TESS Objects of Interest have been catalogued,
no comprehensive survey of the flare rates of their host stars exists.
We perform the first flare survey of all 2250 non-retired TOIs with
2-min cadence light curves to measure or place upper limits on their
flare rates. We find 93 candidates orbit flare stars and measure their
flare frequency distributions. Across the sample, TOIs of ≤
1.5R⊕ orbit flare stars more frequently than do TOIs of
1.5 < R < 2.75R_{Earth}_, 2.75 < R< 4R_{Earth}_, or R => 4R⊕.
We sort all TOI host stars by their flare rate/upper limit, stellar
mass, and distance to create a flare ranking metric (FRM) to determine
suitability for follow-up. The FRM of each TOI is then checked against
the expected signal-to-noise of atmospheric features in transmission
spectroscopy to locate the most promising targets. We find 1/4 of
terrestrial M-dwarf planets amenable to transmission spectroscopy
orbit flare stars. However, none of the M-dwarf hosts to terrestrial
planets are currently flaring at sufficient levels for > 99.9 per cent
atmospheric ozone depletion. We give the first upper limits on the
flare rate of the host star to TOI 700 d and explore the flare rates
incident on young planets such as DS Tuc Ab.
Description:
In this work, we characterize flare rates of TESS stars catalogued on
selected TOIs with 2-min cadance photometry downloaded for 2250 TOI
planet candidates and 2096 host stars. We detect flare automatically
with an light curve alogrithm described in Howard & MacGregor
(2022ApJ...926..204H 2022ApJ...926..204H, Cat. J/ApJ/926/204). We compute FRM, TSM and
flare rates in order to sort all TOI host stars by stellar mass, and
distance and thus determine the sample of the best signal-to-noise
spectroscopic atmospheric features.
With the launch of JWST and increasing numbers of space and
ground-based measurements of exoplanet atmospheres, exoplanet science is
moving beyond discovery into detailed characterization. Exoplanet
characterization efforts require a careful treatment of starspots and
flares to avoid false positives (FPs) in atmospheric line or
bio-signature detections and to probe non-equilibrium atmospheric
states resulting from high rates of flaring. We present all these
analysis results in the table.dat of 2250 TOIs systems.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 308 2250 Flares catalog of all 2250 TOIs with 2-min
cadence TESS data and a non false positive
disposition
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See also:
J/ApJS/254/39 : Exoplanet candidates from TESS first 2yr obs (Guerrero+, 2021)
J/ApJ/926/204 : TESS monitoring campaign of low-mass flare stars (Howard+,2022)
J/A+A/623/A72 : Binarity of Hipparcos stars from Gaia pm anomaly
(Kervella+, 2019)
J/AJ/160/188 : Spectroscopic transit depths of LHS 3844b (Diamond-Lowe+, 2020)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
I/347 : Distances to 1.33 billion stars in Gaia DR2
(Bailer-Jones+, 2018)
https://exofop.ipac.caltech.edu/tess/ : ExoFOP data
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- TOI TESS Objects of Interest identifier number
(TOI)
9- 14 F6.2 Rgeo Rp Planet radius (planetradiusRe) (1)
16- 21 F6.2 Rgeo e_Rp ?=-99.0 Mean uncertainty of Rp
(eplanetradius_Re)
23- 28 F6.3 au Orb ?=-1.0 Planet orbital distance (orbdistau)
30- 35 F6.3 au e_Orb ?=-1.0 Mean uncertainty of Orb (eorbdist_au)
37- 42 F6.2 d Per ?=0.0 Planet orbital period (orbperiodd) (2)
44- 47 F4.2 d e_Per ?=0.0 Mean uncertainty of Per (eorbperiod_d)
49 A1 --- TFOP TESS Follow-up Observing Program disposition
(TFOP_disp) (3)
51 I1 --- Priority TOI flare order of priority from 1 to 5 ranks
(master_priority)
53- 62 I10 --- TIC TESS input catalog identifier (TICID)
64 I1 --- Bin Binary flag takes whether 2 for 2167 sources
or 3 for 83 sources (table_bool) (4)
66- 84 I19 --- GaiaDR2 Gaia DR2 unique identifier number (GAIA_ID)
86- 95 F10.6 deg RAdeg Barycentric right ascension (ICRS) at
Ep=2015.5 (coord_RA)
97-106 F10.6 deg DEdeg Barycentric declination (ICRS) at Ep=2015.5
(coord_Dec)
108-116 F9.6 mag Tmag TESS magnitude from TIC Stassun et al.
2019AJ....158..138S 2019AJ....158..138S, Cat. IV/38 (Tmags)
118-127 F10.5 pc D* ?=-1.0 Stellar distance from TIC Stassun et
al. 2019AJ....158..138S 2019AJ....158..138S, Cat. IV/38
(stellardistancepc)
129 I1 --- f_D* [0/1] Stellar distance availability flag, 0
for 2246 sources and 1 for 4 sources
(stellardistancebool)
131-145 F15.12 Msun M* ?=-1.0 Stellar mass from TIC Stassun et al.
2019AJ....158..138S 2019AJ....158..138S, Cat. IV/38 (stellar_mass)
147-161 F15.13 Msun e_M* Mean uncertainty of M* (estellarmass)
163 I1 --- Binarity Binarity boolean takes whether 0 for 2212
sources or 1 for 38 sources (binarity_bool)
(4)
165 I1 --- Contam Flag which tags source contamination is
likely present, takes 0 for 2079 sources or 1
for 171 sources (contam_bool)
167 I1 --- ExpBin Exposed binarity boolean takes whether 0 for
2247 sources or 1 for 3 sources
(expbinarity_bool)
169-174 F6.2 s Obs Observation time (obstimed)
176-178 I3 --- Nfl Number of flares observed (N_flares)
180-184 F5.2 10-7J EminU Smallest energy flare used to detect flares
(MinUse_Erg)
186-190 F5.2 10-7J Emin100 Smallest energy flare that would be recovered
100 per cent of the time (MinCompl_Erg)
192-196 F5.1 s EDU Smallest the equivalent duration used for
detection of each flare obtained by
integrating the fractional flux between the
start and stop times in seconds (MinUse_ED)
198-202 F5.1 s ED100 Smallest the equivalent duration would be
recovered 100 per cent of the time
(MinCompl_ED)
204-210 F7.3 1/yr ED The equivalent duration flare rate
(EDflarerate)
212-217 F6.3 --- 1-alpha Fit parameter 1-α from flare frequency
distribution FFD computations
(oneminalpha_ffd) (5)
219-225 F7.4 --- e_1-alpha ?=-1.0 Lower uncertainty of 1-α from
1σ confidence interval
(eoneminalphaffd)
227-233 F7.4 --- E_1-alpha ?=-1.0 Upper uncertainty of 1-α from
1σ confidence interval
(Eoneminalphaffd)
235-241 F7.3 --- beta Fit parameter β from flare frequency
distribution FFD computations (beta_ffd) (5)
243-249 F7.4 --- e_beta ?=-1.0 Lower uncertainty of β from
1σ confidence interval (ebetaffd)
251-257 F7.4 --- E_beta ?=-1.0 Upper uncertainty of β from
1σ confidence interval (Ebetaffd)
259-269 F11.4 1/yr Nsuper The superflare rate number for energy flare
equal or greater than 1034 erg
(superflare_rate)
271-282 F12.5 1/yr e_Nsuper ?=-1.0 Lower uncertainty of Nsuper from
1σ confidence interval
(esuperflarerate)
284-295 F12.5 1/yr E_Nsuper ?=-1.0 Upper uncertainty of Nsuper from
1σ confidence interval
(Esuperflarerate)
297-302 F6.4 --- FRM The flare ranking metric (FRM) (6)
304-308 F5.1 --- TSM The transmission spectroscopy metric
(TSMKemptonetal2018) (7)
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Note (1): Length of a line segment from the center of the planet to its surface,
measured in units of radius of the Earth.
Note (2): Time the planet takes to make a complete orbit around the host star
or system.
Note (3): TFOP dispositions are as follows:
Y = yes, confirmed planet candidate or known planet, 1794 sources in
our sample
N = no, false positive or false alarm planet, 315 sources in our
sample
M = maybe, ambiguous planetary candidate, 141 sources in our sample
Note (4): A flag for binarity in Gaia DR2
(Kervella et al. 2019A&A...623A..72K 2019A&A...623A..72K, Cat. J/A+A/623/A72) or source
contamination is likely present.
Note (5): As explained in section 2.1, Flare frequency distributions (FFDs)
are computed for each TOI given the cumulative rate at which flares
of energy E or greater are observed per day and the total observing
time. The FFD is fit in log-log space with
logν = (1-α)*logE + β where ν is the number of
flares with an energy greater than or equal to E in erg per day,
1-α describes the frequency at which flares of various energies
occur and β determines the overall rate of flaring.
Note (6): As explicited in the section 3, this TOI FRM sorts TOIs by increasing
flare rate within distinct groupings organized by stellar mass and
distance, with nearby, low-mass stars ranked higher than distant,
high-mass stars.
Note (7): Once each TOI is assigned its final flare ranking, we cross-correlate
the flare catalogue with those targets for which a 10-h JWST program
could detect exoplanet atmospheres. Following Kempton et al.
(2018PASP..130k4401K 2018PASP..130k4401K), we compute a transmission spectroscopy metric
(TSM) for each TOI in our sample as the equation 2 of the section 3
describes it. The TSM scales with the signal-to-noise of exoplanet
atmospheric features, assuming a cloud-free atmosphere and 10-h of
JWST observations.
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 25-Mar-2025