J/AJ/169/302 Light curves & spectra of two giant M dwarf flares (Corbett+, 2025)
EFTE-SOAR: Two giant M dwarf flares with rapid spectroscopic follow-up.
Corbett H., Galliher N., Glazier A., Gonzalez Chavez R., Law N.M.,
Howard W.S., Soto A.V., Ratzloff J.K., Quimby R.
<Astron. J., 169, 302 (2025)>
=2025AJ....169..302C 2025AJ....169..302C
ADC_Keywords: Stars, flare; Balmer lines; Equivalent widths; Spectra, optical;
Photometry; Transient
Keywords: Stellar flares ; Stellar activity ; Wide-field telescopes ;
Spectroscopy
Abstract:
We present time-series optical spectroscopy of two stellar flares with
complex multi-peaked light curves: a 2.1-.3+.4x1034erg flare
from an M8 ultra-cool dwarf, and a 1.5-.2+.2x1035erg superflare
from an M4 field star. Both flares were discovered by the Evryscope
Fast Transient Engine and observed with the Southern Astrophysical
Research 4.1m telescope ∼10min after their initial peak. We model the
blackbody temperature of the flares as a function of time, finding
that the characteristic temperature reaches ∼13,000K during the
secondary peaks of both events and is likely higher during the
initial, unobserved impulsive phase. Both nonthermal emission from the
near-UV Balmer continuum and an evolving red continuum of uncertain
origin are observed in both flares; we compare the relative
contributions of the continua, line emission, and blackbody component
as the flare evolves, and find that the secondary peak of the M4
superflare immediately follows inversion of the relative contributions
of the Balmer and red continua. We additionally present a model that
constrains the evolution of the electron density of the stellar
chromosphere during the flare, based on the time evolution of the
observed red continuum excess, which we interpret as components of the
hydrogen recombination continuum. Our observations of a 10.5mag flare
from an M8 dwarf, as well as a similar, unusually energetic event from
an M4 dwarf, are comparable in intensity to the most energetic stellar
flares reported in the literature to date.
Description:
EVRT-2509887 was first detected in an Evryscope-South image taken on
2019 December 5 at 3:45:25UT, located at 01:27:18 -60:57:43 with a
g-band magnitude of 10.6. EVRT-2509887 was located in an overlap
between two cameras in the Evryscope array, and a second detection was
made 42s later at 03:46:35UT. The flare was subsequently detected in
five additional frames, at approximately 1min cadence. The observed
light curve of the flare as observed by Evryscope, the All Sky
Automated Survey for SuperNovae (ASAS-SN), and the SOAR 4.1m telescope
is shown in this work. The presented SOAR photometry is generated from
the follow-up spectroscopy, and the ASAS-SN photometry is
serendipitous, accessed archivally using the ASAS-SN Sky Patrol.
EVRT-3586872 was first detected in an Evryscope-South image from 2020
February 15 at 05:40:57UT with a g-band magnitude of 13.1. An alert
to observers including this catalog data was produced by EFTE at
5:45:33UT, and observations with SOAR began at 5:55:48UT.
Both EVRT-2509887 and EVRT-3586872 were observed by SOAR using the
400lines/mm grating in the M1 configuration, providing spectral
coverage between 300 and 400nm. We selected the 1.0" slit for
EVRT-2509887 and the 1.2" slit for EVRT-3586872, producing slit widths
of 6.7Å and 8Å, respectively, along the spectral axis.
The Evryscopes are a pair of all-sky telescopes, based at Cerro-Tololo
Inter-American Observatory in the Southern Hemisphere and Mount Laguna
Observatory, outside of San Diego, California, in the Northern
Hemisphere. Each site consists of many 6.1cm telescopes (currently 20
in the north, 24 in the south) that track the sky in 2hr intervals.
This allows for continuous coverage of 16,512deg2 at 2min cadence
with 13"/pixel sampling. Evryscope data are reduced and analyzed in
real time to search for short-duration and rapidly evolving transient
sources using the custom-developed Evryscope Fast Transient Engine
(EFTE) pipeline.
To produce an alert to observers, events were required to meet
standard EFTE quality metrics, cross-match with a known catalog
source, and produce at least two detections during a rolling 10min
time window. We also required that the two detections have a minimum
separation of at least 120s. On average, this resulted in 3-4
high-confidence candidate flares per night, one or two of which we
selected for spectroscopic follow-up based on their amplitudes and the
latency from their apparent peak as observed by Evryscope. We
attempted to follow each flare for 1-3hr, or until we were unable to
obtain a signal-to-noise ratio SNR∼5 spectrum in a 5-10min exposure.
From this data set, we select two high-amplitude flares with complex
decay-phase light curves and a clear secondary peak for analysis here.
Objects:
---------------------------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------------------------
01 27 17.16 -60 57 33.5 EVRT-2509887 = 2MASS J01271715-6057334
08 59 35.84 -23 40 20.1 EVRT-3586872 = 2MASS J08593584-2340201
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File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 141 2 EFTE Flare discovery coordinates, number of
significant detections in Evryscope, peak magnitudes,
and time stamps for detection and alert generation
fig1b.dat 365 85 Fit parameters for the Balmer lines of EVRT-2509887
fig1c.dat 122 85 Fit parameters for the calcium H and K lines of
EVRT-2509887
fig1/* . 5 EVRT-2509887 light curves and equivalent widths
(data behind Figure 1 in MRT format)
fig2b.dat 358 76 Fit parameters for the Balmer lines of EVRT-3586872
fig2c.dat 119 76 Fit parameters for the calcium H and K lines of
EVRT-3586872
fig2/* . 5 EVRT-3586872 light curves and equivalent widths
(data behind Figure 2 in MRT format)
fig3.dat 30 76 List of spectra from the decay phase of EVRT-3586872
(added by CDS)
fig3/* . 78 Spectra from the decay phase of EVRT-3586872
(data behind Figure 3 in MRT format)
fig4.dat 30 85 List of spectra from the decay phase of EVRT-2509887
(added by CDS)
fig4/* . 87 Spectra from the decay phase of EVRT-2509887
(data behind Figure 4 in MRT format)
fig8/* . 4 Temperature and filling factor evolution of both
flares (data behind Figure 8 in MRT format)
--------------------------------------------------------------------------------
See also:
II/179 : Southern Spectrophotometric Standards. I + II (Hamuy+ 1992,94)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/349 : StarHorse, Gaia DR2 photo-astrometric distances (Anders+, 2019)
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
J/ApJ/743/154 : Multi-band phot. of GRB 110205A + 110213A (Cucchiara+, 2011)
J/ApJ/767/95 : Improved stellar param. of smallest KIC stars (Dressing+, 2013)
J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/ApJ/807/45 : Potentially habit. planets orbiting M dwarfs (Dressing+, 2015)
J/ApJS/230/16 : O5 to L3 empirical stellar spectra from SDSS (Kesseli+, 2017)
J/AJ/156/241 : A first cat. of variab. stars measured by ATLAS (Heinze+, 2018)
J/ApJ/858/55 : K2 ultracool dwarfs survey. III. M6-L0 flares (Paudel+, 2018)
J/ApJ/867/105 : ATLAS all-sky stellar ref. cat., ATLAS-REFCAT2 (Tonry+, 2018)
J/ApJ/881/9 : EvryFlare. I. Cool stars's flares in southern sky (Howard+, 2019)
J/AJ/157/231 : MLSDSS-GaiaDR2 sample of M and L dwarfs (Kiman+, 2019)
J/ApJ/876/115 : Optical follow-up of ASAS-SN M dwarf flares (Schmidt+, 2019)
J/AJ/159/60 : 8695 flares from 1228 stars in TESS Sect. 1 & 2 (Gunther+, 2020)
J/ApJ/902/115 : EvryFlare. III. Superflares: Evryscope & TESS (Howard+, 2020)
J/ApJ/909/106 : R-band LC and spectrum of a superstellar flare (Xin+, 2021)
J/MNRAS/512/L60 : Flare detections of TOI host stars (Howard+, 2022)
J/ApJ/926/204 : TESS monitor. campaign of low-mass flare stars (Howard+, 2022)
J/ApJ/960/62 : Red dwarfs, Xray, UV, and CaII (Engle, 2024)
http://asas-sn.ifa.hawaii.edu/skypatrol/ : ASAS-SN Sky Patrol v2.0 database
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Flare Flare identifier
14- 15 I2 h RAh Hour of right ascension (J2000)
17- 18 I2 min RAm Minute of right ascension (J2000)
20- 24 F5.2 s RAs Second of right ascension (J2000)
26 A1 --- DE- Sign of declination (J2000)
27- 28 I2 deg DEd Degree of declination (J2000)
30- 31 I2 arcmin DEm Arcminute of declination (J2000)
33- 37 F5.2 arcsec DEs Arcsecond of declination (J2000)
39- 48 A10 "Y:M:D" Date Date of detection (UT)
50- 57 A8 --- 1stDet Time stamp of first detection (UT)
59- 70 A12 --- TrigTime Trigger time (UT)
72 I1 --- Ndet [3/7] Number of significant detections in
Evryscope
74- 77 F4.1 mag gmag [10.3/12.7] g-band peak magnitude
79- 80 A2 --- LC Associated light curve with link to the
interactive plot (data behind Figure 1.a &
Figure 2.a)
82- 90 A9 --- FileLC Link to the light curve file in MRT format
92- 93 A2 --- EW Associated equivalent width changes with
link to the interactive plot (data behind
Figure 1.bc & 2.bc)
95-103 A9 --- FileEW-H Link to the Balmer lines fit parameters
file in MRT format
105-113 A9 --- FileEW-Ca Link to the Ca lines fit parameters file in
MRT format
115-120 A6 --- TabEW Link to the line fit parameters data (Tables
fig1EW and fig2EW)
122-125 A4 --- Temp Associated best-fit temperature evolution
with link to the interactive plot (data
behind Figure 8)
127-128 A2 --- Xt Associated filling factor evolution (flaring
region size as a fraction of the stellar
disk) with link to interactive plot (data
behind Figure 8)
130-138 A9 --- FileFig8 Link to the temperature and filling factor
evolution file in MRT format
140-141 I2 --- nSp Number of spectra taken during the decay
phase
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig1b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Epoch UTC mid-point of exposure, ISO 8601
format
25- 31 F7.2 10-10m Ha-X0 Halpha peak position (1)
33- 37 F5.1 10+14W/m2/nm Ha-Amp Halpha Lorentzian amplitude; 1e+16
erg/s/cm/Angstrom (1)
39- 42 F4.2 10-10m Ha-FWHM-L Halpha Lorentzian full width at
half maximum (2)
44- 48 F5.2 10-10m Ha-FWHM-G Halpha Gaussian full width at half
maximum (2)
50- 56 F7.2 10-10m Ha-EW Halpha equivalent width
58- 61 F4.2 10-10m e_Ha-EW Uncertainty in Ha-EW
63- 69 F7.3 --- Ha-SNR Halpha signal-to-noise ratio (3)
71- 77 F7.2 10-10m Hb-X0 Hbeta peak position (1)
79- 83 F5.1 10+14W/m2/nm Hb-Amp Hbeta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
85- 88 F4.2 10-10m Hb-FWHM-L Hbeta Lorentzian full width at half
maximum (2)
90- 93 F4.2 10-10m Hb-FWHM-G Hbeta Gaussian full width at half
maximum (2)
95- 101 F7.2 10-10m Hb-EW Hbeta equivalent width
103- 106 F4.2 10-10m e_Hb-EW Uncertainty in Hb-EW
108- 114 F7.3 --- Hb-SNR Hbeta signal-to-noise ratio (3)
116- 122 F7.2 10-10m Hg-X0 Hgamma peak position (1)
124- 129 F6.1 10+14W/m2/nm Hg-Amp Hgamma Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
131- 135 F5.2 10-10m Hg-FWHM-L Hgamma Lorentzian full width at
half maximum (2)
137- 141 F5.2 10-10m Hg-FWHM-G Hgamma Gaussian full width at half
maximum (2)
143- 149 F7.2 10-10m Hg-EW Hgamma equivalent width
151- 154 F4.2 10-10m e_Hg-EW Uncertainty in Hg-EW
156- 161 F6.3 --- Hg-SNR Hgamma signal-to-noise ratio (3)
163- 169 F7.2 10-10m Hd-X0 Hdelta peak position (1)
171- 176 F6.1 10+14W/m2/nm Hd-Amp Hdelta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (2)
178- 183 F6.2 10-10m Hd-FWHM-L Hdelta Lorentzian full width at
half maximum (2)
185- 190 F6.2 10-10m Hd-FWHM-G Hdelta Gaussian full width at half
maximum (2)
192- 198 F7.2 10-10m Hd-EW Halpha equivalent width
200- 204 F5.2 10-10m e_Hd-EW Uncertainty in Hd-EW
206- 211 F6.3 --- Hd-SNR Hdelta signal-to-noise ratio (3)
213- 219 F7.2 10-10m Heps-X0 Hepsilon peak position (1)
221- 226 F6.1 10+14W/m2/nm Heps-Amp Hepsilon Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
228- 233 F6.2 10-10m Heps-FWHM-L Hepsilon Lorentzian full width at
half maximum (2)
235- 240 F6.2 10-10m Heps-FWHM-G Hepsilon Gaussian full width at
half maximum (2)
242- 249 F8.2 10-10m Heps-EW Hepsilon equivalent width
251- 255 F5.2 10-10m e_Heps-EW Uncertainty in He-EW
257- 262 F6.3 --- Heps-SNR Hepsilon signal-to-noise ratio (3)
264- 270 F7.2 10-10m Hz-X0 Hzeta peak position (1)
272- 277 F6.1 10+14W/m2/nm Hz-Amp Hzeta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
279- 284 F6.2 10-10m Hz-FWHM-L Hzeta Lorentzian full width at half
maximum (2)
286- 291 F6.2 10-10m Hz-FWHM-G Hzeta Gaussian full width at half
maximum (2)
293- 300 F8.2 10-10m Hz-EW Hzeta equivalent width
302- 306 F5.2 10-10m e_Hz-EW Uncertainty in Hz-EW
308- 313 F6.3 --- Hz-SNR Hzeta signal-to-noise ratio (3)
315- 321 F7.2 10-10m Heta-X0 Heta peak position (1)
323- 329 F7.1 10+14W/m2/nm Heta-Amp Heta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
331- 336 F6.2 10-10m Heta-FWHM-L Heta Lorentzian full width at half
maximum (2)
338- 343 F6.2 10-10m Heta-FWHM-G Heta Gaussian full width at half
maximum (2)
345- 352 F8.2 10-10m Heta-EW Heta equivalent width
354- 358 F5.2 10-10m e_Heta-EW Uncertainty in He-EW
360- 365 F6.3 --- Heta-SNR Heta signal-to-noise ratio (3)
--------------------------------------------------------------------------------
Note (1): from fitting a Voigt profile to the line.
Note (2): from Voigt profile fit to the line.
Note (3): Relative to nearby continuum.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig1c.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Epoch UTC mid-point of exposure, ISO 8601
format
25- 31 F7.2 10-10m H-X0 Ca II H line peak position (1)
33- 39 F7.1 10+14W/m2/nm H-Amp Ca II H line Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
41- 44 F4.2 10-10m H-FWHM-L Ca II H line Lorentzian full width at
half maximum (2)
46- 50 F5.2 10-10m H-FWHM-G Ca II H line Gaussian full width at
half maximum (2)
52- 59 F8.2 10-10m H-EW Ca II H line equivalent width
61- 65 F5.2 10-10m e_H-EW Uncertainty in H-EW
67- 72 F6.3 --- H-SNR Ca II H line signal-to-noise ratio (3)
74- 80 F7.2 10-10m K-X0 Ca II K line peak position (1)
82- 90 F9.1 10+14W/m2/nm K-Amp Ca II K line Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
92- 95 F4.2 10-10m K-FWHM-L Ca II K line Lorentzian full width at
half maximum (2)
97- 100 F4.2 10-10m K-FWHM-G Ca II K line Gaussian full width at
half maximum (2)
102- 109 F8.2 10-10m K-EW Ca II K line equivalent width
111- 115 F5.2 10-10m e_K-EW Uncertainty in K-EW
117- 122 F6.3 --- K-SNR Ca II K line signal-to-noise ratio (3)
--------------------------------------------------------------------------------
Note (1): from fitting a Voigt profile to the line.
Note (2): from Voigt profile fit to the line.
Note (3): Relative to nearby continuum.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Epoch UTC mid-point of exposure, ISO 8601
format
25- 31 F7.2 10-10m Ha-X0 Halpha peak position (1)
33- 39 F7.1 10+14W/m2/nm Ha-Amp Halpha Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
41- 44 F4.2 10-10m Ha-FWHM-L Halpha Lorentzian full width at
half maximum (2)
46- 51 F6.2 10-10m Ha-FWHM-G Halpha Gaussian full width at half
maximum (2)
53- 58 F6.2 10-10m Ha-EW Halpha equivalent width
60- 63 F4.2 10-10m e_Ha-EW Uncertainty in Ha-EW
65- 71 F7.3 --- Ha-SNR Halpha signal-to-noise ratio (3)
73- 79 F7.2 10-10m Hb-X0 Hbeta peak position (1)
81- 87 F7.1 10+14W/m2/nm Hb-Amp Hbeta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
89- 92 F4.2 10-10m Hb-FWHM-L Hbeta Lorentzian full width at half
maximum (2)
94- 98 F5.2 10-10m Hb-FWHM-G Hbeta Gaussian full width at half
maximum (2)
100- 106 F7.2 10-10m Hb-EW Hbeta equivalent width
108- 111 F4.2 10-10m e_Hb-EW Uncertainty in Hb-EW
113- 119 F7.3 --- Hb-SNR Hbeta signal-to-noise ratio (3)
121- 127 F7.2 10-10m Hg-X0 Hgamma peak position (1)
129- 135 F7.1 10+14W/m2/nm Hg-Amp Hgamma Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
137- 140 F4.2 10-10m Hg-FWHM-L Hgamma Lorentzian full width at
half maximum (2)
142- 147 F6.2 10-10m Hg-FWHM-G Hgamma Gaussian full width at half
maximum (2)
149- 154 F6.2 10-10m Hg-EW Hgamma equivalent width
156- 159 F4.2 10-10m e_Hg-EW Uncertainty in Hg-EW
161- 167 F7.3 --- Hg-SNR Hgamma signal-to-noise ratio (3)
169- 175 F7.2 10-10m Hd-X0 Hdelta peak position (1)
177- 183 F7.1 10+14W/m2/nm Hd-Amp Hdelta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (2)
185- 189 F5.2 10-10m Hd-FWHM-L Hdelta Lorentzian full width at
half maximum (2)
191- 195 F5.2 10-10m Hd-FWHM-G Hdelta Gaussian full width at half
maximum (3)
197- 202 F6.2 10-10m Hd-EW Halpha equivalent width
204- 207 F4.2 10-10m e_Hd-EW Uncertainty in Hd-EW
209- 215 F7.3 --- Hd-SNR Hdelta signal-to-noise ratio (3)
217- 223 F7.2 10-10m Heps-X0 Hepsilon peak position (1)
225- 231 F7.1 10+14W/m2/nm Heps-Amp Hepsilon Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
233- 237 F5.2 10-10m Heps-FWHM-L Hepsilon Lorentzian full width at
half maximum (2)
239- 243 F5.2 10-10m Heps-FWHM-G Hepsilon Gaussian full width at
half maximum (2)
245- 251 F7.2 10-10m Heps-EW Hepsilon equivalent width
253- 256 F4.2 10-10m e_Heps-EW Uncertainty in He-EW
258- 264 F7.3 --- Heps-SNR Hepsilon signal-to-noise ratio (3)
266- 272 F7.2 10-10m Hz-X0 Hzeta peak position (1)
274- 280 F7.1 10+14W/m2/nm Hz-Amp Hzeta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
282- 285 F4.2 10-10m Hz-FWHM-L Hzeta Lorentzian full width at half
maximum (2)
287- 291 F5.2 10-10m Hz-FWHM-G Hzeta Gaussian full width at half
maximum (2)
293- 298 F6.2 10-10m Hz-EW Hzeta equivalent width
300- 303 F4.2 10-10m e_Hz-EW Uncertainty in Hz-EW
305- 311 F7.3 --- Hz-SNR Hzeta signal-to-noise ratio (3)
313- 319 F7.2 10-10m Heta-X0 Heta peak position (1)
321- 327 F7.1 10+14W/m2/nm Heta-Amp Heta Lorentzian amplitude; 1e-16
erg/s/cm/Angstrom (1)
329- 333 F5.2 10-10m Heta-FWHM-L Heta Lorentzian full width at half
maximum (2)
335- 339 F5.2 10-10m Heta-FWHM-G Heta Gaussian full width at half
maximum (2)
341- 346 F6.2 10-10m Heta-EW Heta equivalent width
348- 351 F4.2 10-10m e_Heta-EW Uncertainty in He-EW
353- 358 F6.3 --- Heta-SNR Heta signal-to-noise ratio (3)
--------------------------------------------------------------------------------
Note (1): from fitting a Voigt profile to the line.
Note (2): from Voigt profile fit to the line.
Note (3): Relative to nearby continuum.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2c.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Epoch UTC mid-point of exposure, ISO 8601
format
25- 31 F7.2 10-10m H-X0 Ca II H line peak position (1)
33- 40 F8.1 10+14W/m2/nm H-Amp Ca II H line Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
42- 45 F4.2 10-10m H-FWHM-L Ca II H line Lorentzian full width at
half maximum (2)
47- 50 F4.2 10-10m H-FWHM-G Ca II H line Gaussian full width at
half maximum (2)
52- 58 F7.2 10-10m H-EW Ca II H line equivalent width
60- 63 F4.2 10-10m e_H-EW Uncertainty in H-EW
65- 71 F7.3 --- H-SNR Ca II H line signal-to-noise ratio (3)
73- 79 F7.2 10-10m K-X0 Ca II K line peak position (1)
81- 89 F9.1 10+14W/m2/nm K-Amp Ca II K line Lorentzian amplitude;
1e-16 erg/s/cm/Angstrom (1)
91- 94 F4.2 10-10m K-FWHM-L Ca II K line Lorentzian full width at
half maximum (2)
96- 99 F4.2 10-10m K-FWHM-G Ca II K line Gaussian full width at
half maximum (2)
101- 106 F6.2 10-10m K-EW Ca II K line equivalent width
108- 111 F4.2 10-10m e_K-EW Uncertainty in K-EW
113- 119 F7.3 --- K-SNR Ca II K line signal-to-noise ratio (3)
--------------------------------------------------------------------------------
Note (1): from fitting a Voigt profile to the line.
Note (2): from Voigt profile fit to the line.
Note (3): Relative to nearby continuum.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig3.dat fig4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Epoch Time of observation
10 A1 --- Flag Flag marking the quiescent flux spectrum
12- 13 A2 --- Sp Associated spectrum with link to the interactive
plot
15- 30 A16 --- File Link to the spectrum file in MRT format
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 03-Mar-2026