J/A+A/694/A157 Earth 2.0 candidates stellar magnetic activity (Su+, 2025)
Stellar magnetic activity in Earth 2.0 candidates based on LAMOST DR10.
Su T., Zhang L., Han X.L., Misra P., Zhu Z., Pi Q.
<Astron. Astrophys. 694, A157 (2025)>
=2025A&A...694A.157S 2025A&A...694A.157S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, activity ; Effective temperatures ; Radial velocities ;
Abundances ; Equivalent widths ; Stars, masses
Keywords: catalogs - surveys - stars: activity - stars: chromospheres
Abstract:
Stellar chromospheric activity can impact the search for exoplanets.
Earth 2.0 (ET 2.0) is a space telescope designed for exoplanet
detection. This work surveys stellar chromospheric activity in the
ET2.0 target regions to enhance the detection rate of exoplanets. This
work uses Halpha and Ca ii H&K lines as indicators of chromospheric
activity and conducts a survey of stellar chromospheric activity in
the ET2.0 target regions using LAMOST low- and medium-resolution
spectra. After cross-referencing with the ET 2.0 input catalog, we
obtained over 349000 low-resolution spectra and over 30000
medium-resolution spectra from LAMOST. We quantified the chromospheric
activity intensity for all spectra and selected the results for those
with a signal-to-noise ratio (S/N) above 10 for further study of
chromospheric activity. The quantification standards include
equivalent width (EW) and the ratio of bolometric luminosity to the
corresponding spectral line luminosity (LHalpha/Lbol,
LCaH/Lbol, LCaK/Lbol, LHK/Lbol). Utilizing Halpha and CaII
H&K lines, we evaluate chromospheric activity for over 320000 and
110000 spectra based on LAMOST low-resolution spectra, respectively.
Additionally, we evaluated chromospheric activity for 34000 spectra
using Halpha lines based on medium-resolution spectra. And select
samples suitable for exoplanet studies based on Halpha and CaII H&K
lines. Additionally, we explore the relationship between stellar
activity observed by LAMOST and rotation periods obtained from Kepler
and TESS surveys. Our findings confirm the presence of two distinct
regions in the relationship between stellar activity and Rossby number
(Ro): saturated and unsaturated. We determined a critical Ro in the
range of 0.09 to 0.12 using r-band spectra of 11921 stars and u-band
spectra of 6120 stars. Moreover, we observe that CaII H&K lines
exhibit greater sensitivity to Ro in the unsaturated region compared
to Halpha line measurements. Lastly, we establish positive
correlations between various activity indicators, including R'CaK,
R'CaH, R'HK and R'Halpha.
Description:
Table A1 presents various stellar parameters derived from LAMOST
low-resolution spectra, along with the intensities of various
chromospheric activity indicators. Table A2 displays the stellar
parameters obtained from LAMOST medium-resolution spectra, as well as
the quantified results of the equivalent width of the Halpha line.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 223 349709 Low-resolution spectral parameters
tablea2.dat 125 30792 Medium-resolution spectral parameters
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See also:
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST name (JHHMMSS.ss+DDMMSS.s)
21- 31 F11.5 d HJD Heliocentric Julian Date
33- 39 F7.2 s ExpTime Spectral exposure time
41- 43 I3 --- snru ? u-band signal-to-noise ratio
45- 47 I3 --- snrg ? g-band signal-to-noise ratio
49- 51 I3 --- snrr ? r-band signal-to-noise ratio
53- 55 I3 --- snri ? i-band signal-to-noise ratio
57- 59 I3 --- snrz ? g-band signal-to-noise ratio
61- 66 F6.2 mag Gmag ? G-band magnitude in Gaia DR3
68- 69 A2 --- subclass Stellar spectral type
71- 74 I4 K Teff ? Effective temperature
76- 78 I3 K e_Teff ? Error in Teff
80- 85 F6.3 [cm/s2] logg ? Surface gravity
87- 92 F6.3 [cm/s2] e_logg ? Error in logg
94- 99 F6.3 [-] [Fe/H] ? Metallicity
101-106 F6.3 [-] e_[Fe/H] ? Error in [Fe/H]
108-114 F7.2 km/s RVLAMOST ? Radial velocity
116-121 F6.2 km/s e_RVLAMOST ? Error in Radial velocity
123-131 F9.3 0.1nm EWHa ? The equivalent width of the Halpha line
133-140 F8.3 0.1nm e_EWHa ? Error in EWHa
142-148 F7.3 0.1nm EWCaK ? The equivalent width of the CaII K line
150-156 F7.3 0.1nm e_EWCaK ? Error in EWCaK
158-164 F7.3 0.1nm EWCaH ? The equivalent width of the CaII H line
166-171 F6.3 0.1nm e_EWCaH ? Error in EWCaH
173-178 F6.3 --- Sindex ? The S-index derived from the
CaII H & K lines
180-185 F6.3 --- e_Sindex ? Error in Sindex
187-197 F11.5 d Prot ? Stellar rotation period
199-204 F6.3 Msun Mass ? Stellar mass
206-215 F10.5 --- Ro ? Rossby number
217 A1 --- VEWHa Halpha line variation
219 A1 --- VEWCaIIK CaII K line variation
221 A1 --- VEWCaIIH CaII H line variation
223 I1 --- P [0/4]? Observation priority
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST name (JHHMMSS.ss+DDMMSS.s)
21- 32 F12.5 d HJD ? Heliocentric Julian Date
34- 36 I3 --- SNR Signal-to-noise ratio
38- 41 I4 K Teff ? Effective temperature
43- 45 I3 K e_Teff ? Error in effective temperature
47- 52 F6.3 [cm/s2] logg ? Surface gravity
54- 59 F6.3 [cm/s2] e_logg ? Error in surface gravity
61- 66 F6.3 [-] [Fe/H] ? Metallicity
68- 73 F6.3 [-] e_[Fe/H] ? Error in [Fe/H]
75- 83 F9.3 0.1nm EWHa The equivalent width of the Halpha line
85- 92 F8.3 0.1nm e_EWHa Error in EW_Halpha
94 A1 --- VEWHa Halpha line variation
96-104 F9.5 --- Prot ? Stellar rotation period
106-110 F5.2 Msun Mass ? Stellar mass
112-116 F5.2 Msun e_Mass ? Error in Mass
118-125 F8.5 --- Ro ? Rossby number
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Acknowledgements:
Su Tianhao, 4828783(at)qq.com
Liyun Zhang, liy_zhang(at)hotmail.com
(End) Patricia Vannier [CDS] 31-Dec-2024