J/MNRAS/495/1252 Magnetic activity based on LAMOST and Kepler (Zhang+, 2020)
Magnetic activity based on LAMOST medium-resolution spectra and the Kepler
survey.
Zhang L.-Y., Long L., Shi J., Lu H.-P., Gao Q., Han X.L., Wang H.,
Prabhakar M., (the Lamost MRS Collaboration)
<Mon. Not. R. Astron. Soc., 495, 1252-1270 (2020)>
=2020MNRAS.495.1252Z 2020MNRAS.495.1252Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Stars, activity ; Stars, flare ;
Stars, variable ; Spectral types ; Equivalent widths ;
Abundances, [Fe/H] ; Effective temperatures ; Stars, masses ;
Stars, diameters ; Spectra, optical ; Photometry, ugriz ;
Photometry, infrared
Keywords: stars: activity - stars: chromospheres - stars: flare -
stars: rotation
Abstract:
Stellar magnetic activity is an interesting phenomenon in late-type
stars. We use the medium-resolution spectroscopic observations of
406069 late-type stars from LAMOST to explore their properties. We
perform a statistical analysis on the magnetic activity of the stars
and their associated physical parameters. Our samples are
cross-matched with other data bases (LAMOST DR5, VSX, and SDSS DR12)
to obtain additional observational properties. The equivalent widths
(EWs) of Hα lines, an indicator of chromospheric activity, are
calculated. According to the EWs of the Hα line, we detect 8816
spectra with apparent Hα emission for a total of 2115 stars
among the 2108565 spectra analysed. Furthermore, 1521 of these stars
show variability in their Hα lines. In addition, we detect 2132
flare events associated with 41542 stars from the catalogue by
cross-matching our LAMOST medium-resolution samples and the Kepler and
K2 data bases. We also confirm a weak relationship of the flare
amplitude with increasing Rossby number. There is a clear decease in
the strength of chromospheric activity (LHα/Lbol) with
increasing rotation period. Moreover, the ratio of the flare energy
and stellar luminosity is found to decrease with the stellar mass.
Description:
LAMOST is a reflecting Schmidt telescope with a field of view of
5°, an effective aperture of 3.6-4.9m, and 4000 fibres (Cui et al.
2012RAA....12.1197C 2012RAA....12.1197C; Luo et al. 2012RAA....12.1243L 2012RAA....12.1243L;
2015RAA....15.1095L 2015RAA....15.1095L, Cat. V/146). LAMOST is located at Xinglong
Station, administered by the National Astronomical Observatories,
Chinese Academy of Sciences (NAOC). The LAMOST survey is an ongoing
low- and medium-resolution spectroscopic survey that aims to determine
stellar atmospheric parameters. LAMOST has released two
medium-resolution (R∼7500) spectral catalogues (DR6 and DR7). The
406069 stars of 2108565 medium-resolution spectra covering
6300-6800Å from LAMOST DR6 and DR7 in the time interval from 2017
September 28 to 2018 December 31 were used in the present study.
We cross-matched our medium-resolution samples from LAMOST DR6 and DR7
with the Kepler (Borucki et al. 2010Sci...327..977B 2010Sci...327..977B, Cat. V/133) and
K2 catalogue (Huber et al. 2014PASP..126..398H 2014PASP..126..398H, Cat. IV/34) with a
tolerance of 3arcsec. Finally, we obtained photometric data related to
4838 and 31557 stars from the Kepler and K2 collections, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 127 2091658 The EWs of Hα line for LAMOST DR6/DR7
medium-resolution spectra
table3.dat 284 247378 The EWs of the Hα line for LAMOST DR5
low-resolution spectra
table4.dat 127 1275481 The values of LHα/Lbol for LAMOST
DR6/DR7 medium-resolution spectra
table5.dat 244 2132 Flare parameters
table6.dat 130 4774 Parameters of 4774 stars cross-matched by
LAMOST medium-resolution spectra and VSX
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See also:
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Source name (JHHMMSS.ss+DDMMSS.s)
21- 29 F9.5 deg RAdeg Right ascension (J2000)
31- 38 F8.5 deg DEdeg Declination (J2000)
40- 58 A19 "Y-M-D,h:m:s" Date Observation date
60- 67 I8 min MJM Modified Julian minute
69- 77 F9.5 --- S/N Signal to noise ratio
79- 84 A6 --- SpType Spectral type
86- 97 F12.9 d Prot ? Rotation period from Kepler and K2
with the Lomb-Scargle method
99- 111 F13.5 0.1nm EWHa ?=99.9 Hα equivalent width (G1)
113- 123 F11.5 0.1nm e_EWHa Error on EWHa
125 A1 --- Emis [YN] Indicates whether there is
emission
127 A1 --- Var [YNO] Indicates whether there is
variation ('Y' for yes, 'N' for no,
'O' for one observation)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- Name Source name (LAMOST JHHMMSS.ss+DDMMSS.s)
28- 46 A19 --- Date Observation date
48- 78 A31 --- MJM Modified Julian minute
80- 93 F14.10 deg RAdeg Right ascension (J2000)
95-108 F14.11 deg DEdeg Declination (J2000)
110-119 A10 --- magType Target magnitude type
121-128 F8.5 mag mag1 ?=99 Magnitude on the first band in magType
130-137 F8.5 mag mag2 ?=99 Magnitude on the second band in magType
139-146 F8.5 mag mag3 ?=99 Magnitude on the third band in magType
148-155 F8.5 mag mag4 ?=99 Magnitude on the fourth band in magType
157-164 F8.5 mag mag5 ?=99 Magnitude on the fifth band in magType
166-173 F8.5 mag mag6 ?=99 Magnitude on the sixth band in magType
175-184 F10.7 mag mag7 ?=99 Magnitude on the seventh band in magType
186-195 A10 --- SpType Spectral type or object class
197-207 F11.7 --- S/Nu Signal to noise ratio on the u filter
209-219 F11.7 --- S/Ng Signal to noise ratio on the g filter
221-231 F11.7 --- S/Nr Signal to noise ratio on the r filter
233-243 F11.7 --- S/Ni Signal to noise ratio on the i filter
245-255 F11.7 --- S/Nz Signal to noise ratio on the z filter
257-267 F11.7 0.1nm EWHa ? Hα equivalent width (G1)
269-282 F14.8 0.1nm e_EWHa ? Error on EWHa
284 A1 --- Emis [YN] Indicates whether there is emission
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Source name (JHHMMSS.ss+DDMMSS.s)
21- 28 I8 min MJM Modified Julian minute
30- 35 F6.2 --- S/N Signal to noise ratio
37- 44 F8.3 K Teff Effective temperature
46- 54 F9.3 K e_Teff []?=-9999 Error on Teff
56- 61 F6.3 [cm/s2] logg Logarithm of the surface gravity
63- 71 F9.3 [cm/s2] e_logg []?=-9999 Error on logg
73- 78 F6.3 [-] [Fe/H] Fe/H abundance ratio
80- 88 F9.3 [-] e_[Fe/H] []?=-9999 Error on [Fe/H]
90- 101 F12.9 [-] logchiHa Logarithm of the ratio between the surface
continuum flux near Hα and the
surface bolometric flux (1)
103- 114 E12.3 --- RHa Chromospheric activity level R'Hα
(2)
116- 127 E12.3 --- e_RHa []? Error on RHa (3)
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Note (1): In this work, we estimated the χHα values using the
following formula: χHα=FHα/(σTeff4)
Note (2): R'Hα=χHαEW', where EW'=EW-EWbasal
Note (3): In the original table there where some values equal to inf, we
replaced these values with 99.9
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Source name (JHHMMSS.ss+DDMMSS.s)
21- 34 A14 --- OName KIC or EPIC star identifier
36- 45 F10.6 deg RAdeg Right ascension (J2000)
47- 55 F9.6 deg DEdeg Declination (J2000)
57- 60 A4 --- Cad [long] Cadence
62- 72 F11.6 d Tstart Flare start time
74- 84 F11.6 d Tpeak Flare peak time
86- 96 F11.6 d Tend Flare end time
98-105 F8.6 d Duration Flare duration
107-114 F8.6 --- Amp Amplitude of the flare
116-137 E22.20 [10-7J] Ebol ? Bolometric energy of the flare
139-160 E22.20 [10-7J] Ekep ? Kepler response flare energy
162-168 F7.2 K Teff Effective temperature
170-178 F9.3 Rsun Rad ?=-9999 Star radius
180-185 F6.4 Msun Mass ? Star mass
187-190 A4 --- SpType Spectral type
192-200 F9.6 d Durtot Total flare duration (1)
202-212 F11.6 d Tobs Total observation time
214-221 F8.6 --- FOR Flare occurence rate (2)
223-231 F9.6 d Prot ? Rotation period
233-245 F13.10 --- Ro ? Rossby number (3)
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Note (1): The total flare duration is obtained by adding the durations of all
observed flares for each star
Note (2): According to Walkowicz et al. (2011AJ....141...50W 2011AJ....141...50W, Cat. J/AJ/141/50)
and Lin et al. (2019ApJ...873...97L 2019ApJ...873...97L), the flare occurence rate (FOR)
can be expressed as the ratio of the total flare time to the total
observation time
Note (3): The Rossby number is defined as Ro=Prot/τ, where τ is the
convective turnover time-scale that is derived from Wright et al.
(2011ApJ...743...48W 2011ApJ...743...48W, Cat. J/ApJ/743/48) using the stellar mass from
the catalogues of Kepler and K2 (Huber et al. 2014ApJS..211....2H 2014ApJS..211....2H,
Cat. J/ApJS/211/2; 2016ApJS..224....2H 2016ApJS..224....2H, Cat. J/ApJS/224/2)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Source name (JHHMMSS.ss+DDMMSS.s)
21- 31 F11.7 deg RAdeg Right ascension (J2000)
33- 42 F10.7 deg DEdeg Declination (J2000)
44 I1 --- Nobs Number of observations
46- 74 A29 --- OName Variable name
76- 93 A18 --- VarType Variability type as in the GCVS catalogue
(Samus et al. 2017ARep...61...80S 2017ARep...61...80S,
Cat. B/gcvs)
95- 100 F6.3 --- Mmax ? Magnitude at maximum or amplitude
102 A1 --- u_Mmax [:] Uncertainty flag on Mmax
104- 114 F11.3 d Epoch ? Epoch of the maximum or minimum (HJD)
116- 128 F13.8 d Period ? Period of the variability
130 A1 --- u_Period [:] Uncertainty flag on Period
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Global Notes:
Note (G1): Some strange values were found in the original data with very large
associated errors. Therefore, we have assigned them the 99.9 value.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 09-Jun-2023