J/MNRAS/494/3596 Superflares in solar-type stars with TESS (Doyle+, 2020)
Superflares and variability in solar-type stars with TESS in the Southern
hemisphere.
Doyle L., Ramsay G., Doyle J.G.
<Mon. Not. R. Astron. Soc., 494, 3596-3610 (2020)>
=2020MNRAS.494.3596D 2020MNRAS.494.3596D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, activity ; Stars, flare ; Positional data ;
Spectral types ; Parallaxes, trigonometric ; Stars, distances ;
Optical
Keywords: stars: activity - stars: flare - stars: magnetic field -
stars: solar-type
Abstract:
Superflares on solar-type stars have been a rapidly developing field
ever since the launch of Kepler. Over the years, there have been
several studies investigating the statistics of these explosive
events. In this study, we present a statistical analysis of stellar
flares on solar-type stars made using photometric data in 2-min
cadence from Transiting Exoplanet Survey Satellite of the whole
Southern hemisphere (sectors 1-13). We derive rotational periods for
all the stars in our sample from rotational modulations present in the
light curve as a result of large star-spot(s) on the surface. We
identify 1980 stellar flares from 209 solar-type stars with energies
in the range of 1031-1036erg (using the solar flare
classification, this corresponds to X1-X100000) and conduct an
analysis into their properties. We investigate the rotational phase of
the flares and find no preference for any phase, suggesting the flares
are randomly distributed. As a benchmark, we use GOES data of solar
flares to detail the close relationship between solar flares and
sunspots. In addition, we also calculate approximate spot areas for
each of our stars and compare this to flare number, rotational phase,
and flare energy. Additionally, two of our stars were observed in the
continuous viewing zone with light-curves spanning 1yr; as a result we
examine the stellar variability of these stars in more detail.
Description:
We identify solar-type stars as those with spectral types ranging from
F7 to K2 according to Simbad (http://simbad.u-strasbg.fr/simbad/), and
have been observed in 2-min cadence by TESS.
First, the sources were cross-referenced with the SkyMapper Southern
Sky Survey (Wolf et al. 2018PASA...35...10W 2018PASA...35...10W, Cat. II/358) and Gaia DR2
(Gaia Collaboration 2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345). Any star that
did not possess SkyMapper magnitudes or Gaia parallaxes was not
considered any further. We use radii and luminosity values from Gaia
DR2 to eliminate any that are likely to be giants and hence wrongly
classified within Simbad. We use Skymapper multicolour magnitudes and
Gaia parallaxes to determine the quiescent luminosity of the stars in
the TESS bandpass. The magnitudes in the g, r, i, and z bands are
converted to flux and then fitted by a polynomial to produce template
spectra of each star. These are then convolved by the TESS bandpass
providing the quiescent flux of each star in the TESS bandpass. By
inverting the Gaia parallaxes, we determine the distances of our
sample and use them to infer the quiescent luminosity of each star.
These values along with the stellar properties of each star are
provided in Table 1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 182 209 The stellar properties of our solar-type star
sample detailing the rotation periods, quiescent
luminosity, energy range, and duration range of
the flares
--------------------------------------------------------------------------------
See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC TESS Input Catalog identifier
11- 25 A15 --- Name Star name
26 A1 --- n_Name [*] Note on Name (1)
27- 41 A15 --- Sector ? TESS Sector (1-13)
43- 50 F8.4 deg RAdeg Right ascension (J2000)
52- 59 F8.4 deg DEdeg Declination (J2000)
61- 66 F6.3 mag gmag ? SkyMapper g-band magnitude
68- 73 F6.3 mag rmag ? SkyMapper r-band magnitude
75- 80 F6.3 mag imag ? SkyMapper i-band magnitude
82- 87 F6.3 mag zmag ? SkyMapper z-band magnitude
89- 91 I3 --- Nf Number of flares
93- 94 A2 --- SpType Spectral type from Simbad
96- 103 F8.5 d Prot Rotation period
105- 112 F8.3 d T0 Phase zero
114- 118 F5.2 mag Tmag TESS magnitude
120- 126 F7.4 mas plx Gaia DR2 parallax
128- 133 F6.4 mas e_plx Error on plx
135- 142 F8.4 pc Dist Distance derived from Gaia DR2 parallax
144- 150 F7.4 pc e_Dist Error on Dist
152- 156 F5.2 [10-7W] logL Logarithm of the quiescent luminosity
158- 162 F5.2 [10-7J] logEmin Logarithm of the flare energy (minimum value)
164- 168 F5.2 [10-7J] logEmax Logarithm of the flare energy (maximum value)
170- 175 F6.2 min tfmin Flare duration range (minimum value)
177- 182 F6.2 min tfmax Flare duration range (maximum value)
--------------------------------------------------------------------------------
Note (1): Note as follows:
* = In the original table, the Name V*CCPhe and its properties were wrongly
assigned to TIC 149248196. The Name and coordinates have been corrected
by the CDS. There are not SkyMapper magnitudes available for this star.
--------------------------------------------------------------------------------
History:
09-Aug-2023: From electronic version of the journal
14-Sep-2023: One Name corrected in Table 1
(End) Ana Fiallos [CDS] 31-May-2023