J/MNRAS/489/437 Origin of stellar flares on M dwarfs using TESS (Doyle+, 2019)
Probing the origin of stellar flares on M dwarfs using TESS data sectors 1-3.
Doyle L., Ramsay G., Doyle J.G., Wu K.
<Mon. Not. R. Astron. Soc., 489, 437-445 (2019)>
=2019MNRAS.489..437D 2019MNRAS.489..437D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Magnetic fields ; Stars, M-type ; Stars, dwarfs ;
Photometry, ugriz ; Spectral types ; Parallaxes, trigonometric ;
Stars, distances
Keywords: stars: activity - stars: flare - stars: low-mass -
stars: magnetic fields
Abstract:
Detailed studies of the Sun have shown that sunspots and solar flares
are closely correlated. Photometric data from Kepler/K2 has allowed
similar studies to be carried out on other stars. Here, we utilize
Transiting Exoplanet Survey Satellite (TESS) photometric 2-min cadence
of 167 low-mass stars from Sectors 1 to 3 to investigate the
relationship between star-spots and stellar flares. From our sample,
90 per cent show clear rotational modulation likely due to the
presence of a large, dominant star-spot and we use this to determine a
rotational period for each star. Additionally, each low-mass star
shows one or more flares in its light curve and using Gaia Data
Release 2 parallaxes and SkyMapper magnitudes we can estimate the
energy of the flares in the TESS band-pass. Overall, we have 1834
flares from the 167 low-mass stars with energies from 6.0x1029 to
2.4x1035erg. We find none of the stars in our sample show any
preference for rotational phase, suggesting the lack of a correlation
between the large, dominant star-spot, and flare number. We discuss
this finding in greater detail and present further scenarios to
account for the origin of flares on these low-mass stars.
Description:
There are a number of strategies for identifying active low-mass stars
in TESS data. For instance Gunther et al. (2019ApJ...876..127Z 2019ApJ...876..127Z)
searched for flares in all of the 2-min cadence TESS data and then
used the temperature extracted from the TESS Input Catalog (TIC;
Stassun et al. 2018AJ....156..102S 2018AJ....156..102S, Cat. J/AJ/156/102) to identify
cool main-sequence stars. Here, we have identified stars that have
been observed in 2-min cadence mode using TESS and have an MV spectral
type in the SIMBAD catalogue.
Our target stars were also cross-referenced with the SkyMapper
Southern Sky Survey (Wolf et al. 2018PASA...35...10W 2018PASA...35...10W, Cat. II/358).
Those which did not possess Gaia Data Release 2 (DR2; Gaia
Collaboration 2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345) parallaxes or SkyMapper
data were not considered further. The SkyMapper multicolour magnitudes
were converted to flux and then fitted using a polynomial, producing a
template spectrum that was convolved with the TESS band-pass to derive
the stars quiescent flux. The Gaia parallaxes were inverted to provide
distances to each star that was used to determine the quiescent
stellar luminosity.
The final sample of low-mass stars observed at 2-min cadence with TESS
consists of 167 M dwarfs. Each sector is observed for ∼27d with 28 per
cent of the sample being observed in more than one sector. The
complete list of our low-mass star TESS sample, including a range of
stellar properties, is provided in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 158 149 Master file of all TESS flare stars from
Sectors 1,2 and 3
tablea1.dat 138 18 Master file of all TESS flare stars from
Sectors 1,2 and 3 which did not show any
modulation
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/156/102 : The TESS Input Catalog and Candidate Target List
(Stassun+, 2018)
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- ID TIC identifier (NNNNNNNNN) (G1)
11- 15 A5 --- Sector Sector (1, 2 or 3)
17- 22 F6.3 mag gmag SkyMapper g-band magnitude
24- 29 F6.3 mag rmag SkyMapper r-band magnitude
31- 36 F6.3 mag imag SkyMapper i-band magnitude
38- 43 F6.3 mag zmag SkyMapper z-band magnitude
45- 46 I2 --- Flare Flare number
48- 50 F3.1 --- SpType Spectral type from Simbad
52- 58 F7.4 d Rot Rotation
60- 67 F8.3 d T0 Phase zero
69- 74 F6.3 mag Tmag TIC magnitude (G1)
76- 83 F8.5 mas plx Gaia DR2 parallax
85- 91 F7.5 mas e_plx Error on plx
93-100 F8.4 pc Dist Distance
102-108 F7.4 pc e_Dist Error on Dist
110-114 F5.2 [10-7W] logLstar Logarithm of star luminosity
116-120 F5.2 [10-7J] logEmin Logarithm of minimum flare energy
122-126 F5.2 [10-7J] logEmax ? Logarithm of maximum flare energy
128-133 F6.2 min tmin Minimum flare duration
135-140 F6.2 min tmax ? Maximum flare duration
142-149 F8.5 arcsec Sep ? Angular separation
151-158 F8.5 mag Deltag ? Difference in gaia brightness
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- ID TIC identifier (NNNNNNNNN) (G1)
11- 27 A17 --- Name Star name
29- 31 A3 --- Sector Sector (1 or 2)
33- 38 F6.3 mag gmag SkyMapper g-band magnitude
40- 46 F7.4 mag rmag SkyMapper i-band magnitude
48- 53 F6.3 mag imag SkyMapper r-band magnitude
55- 60 F6.3 mag zmag SkyMapper z-band magnitude
62- 63 I2 --- Flare Flare number
65- 71 F7.4 mas plx Gaia DR2 parallax
73- 78 F6.4 mas e_plx Error on plx
80- 87 F8.5 pc Dist Distance
89- 95 F7.5 pc e_Dist Error on Dist
97- 99 F3.1 --- SpType Spectral type from Simbad
101-106 F6.3 mag Tmag TIC magnitude (G1)
108-112 F5.2 [10-7W] logLstar Logarithm of star luminosity
114-118 F5.2 [10-7J] logEmin Logarithm of minimum flare energy
120-124 F5.2 [10-7J] logEmax ? Logarithm of maximum flare energy
126-131 F6.2 min tmin Minimum flare duration
133-138 F6.2 min tmax ? Maximum flare duration
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Global Notes:
Note (G1): TIC ID and Tmag taken from (Stassun et al. 2018AJ....156..102S 2018AJ....156..102S,
Cat. J/AJ/156/102)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 02-Jan-2023