J/MNRAS/511/814 EWs from NIR-spectra of Cool giants stars (Ghosh+, 2022)
H-band temperature and metallicity indicators for cool giants empirical
relations in bayesian framework.
Ghosh S., Ninan J.P., Ojha D.K.
<Mon. Not. R. Astron. Soc., 511, 814-828 (2022)>
=2022MNRAS.511..814G 2022MNRAS.511..814G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Spectroscopy ; Infrared ; Equivalent widths ;
Effective temperatures ; Abundances, [Fe/H]
Keywords: methods: observational - techniques: spectroscopic -
stars: fundamental parameters - infrared: stars
Abstract:
We explored here the near-infrared H-band atmospheric window aiming to
provide quantitative diagnostic tools for deriving stellar parameters,
for instance, effective temperature (Teff) and metallicity ([Fe/H]),
of cool giants (Teff < 5000 K) using low-resolution spectra. We
obtained 177 cool giants from the X-shooter spectral library covering
a wider metallicity range (-2.35 dex < [Fe/H] < 0.5 dex) than in
earlier works. Degrading the spectral resolution to R ∼ 1200, we
estimated equivalent widths of several important spectral features,
and the behaviour of spectral features with stellar parameters are
studied. Also, the empirical relations for deriving Teff and [Fe/H]
are established in the Bayesian framework. We found that 12CO at
1.56 and 1.62 µm, and 12CO + MgI at 1.71 µm are the best three
Teff indicators with a typical accuracy of 153, 123, and 107 K,
respectively. The cubic Bayesian model provides the best metallicity
estimator with a typical accuracy of 0.22, 0.28, and 0.24 dex for FeH
at 1.62 µm, 12CO at 1.64 µm, and Fe I at 1.66 µm,
respectively. We also showed a detailed quantitative metallicity
dependence of Teff-EWs correlations defining three metallicity groups,
supersolar ([Fe/H] > 0.0 dex), solar (-0.3 dex < [Fe/H] < 0.3 dex),
and subsolar ([Fe/H] ←0.3 dex), from Hierarchical Bayesian modelling.
The difference between the solar and subsolar relationship is
statistically significant, but such difference is not evident between
the solar and supersolar groups.
Description:
In our work, we aim to precisely determine H-band spectral features of
well-characterized sample stars. We use the second data release of the
X-shooter stellar library (Gonneau et al. 2020A&A...634A.133G 2020A&A...634A.133G, Cat.
J/A+A/634/A133), which contains 813 spectra for 666 stars of various
spectral types. The spectra were observed in the wavelength range
0.3-2.5 µm at a spectral resolution (R) ∼ 10000 using the X-shooter
spectrograph on ESO's VLT. The details about sample selection,
observing strategy, data reduction, and calibration can be found in
Gonneau et al. (2020). The library contains a total of 381 cool giants
(Teff < 5000 K) and a total of 177 cool giants were obtained for this
work. We adopted Teff, logg and [Fe/H] of sample giants from Arentsen
et al. (2019A&A...627A.138A 2019A&A...627A.138A, Cat. J/A+A/627/A138) that are derived
using the full-spectrum fitting package University of Lyon
Spectroscopic analysis Software and the Medium-resolution INT Library
of Empirical Spectra library, (i.e see section Introduction).
In this work, we selected the H-band atmospheric window and computed
equivalent widths (EWs) of a number of prominent spectral features. To
estimate EWs, feature and continuum bands are adopted from various
literature as listed in the section 2 Sample selection. These results
are presented in the table1.dat. All spectral features of our interest
and their corresponding bandpasses are alike to the study of Morelli
et al. (2020A&A...641A..44M 2020A&A...641A..44M, Cat. J/A+A/641/A44). However, our work
represents a step forward with respect to the works which was based on
the small number of cool giants of IRTF spectral library. We degraded
spectral resolution from R ∼ 10000 to R ∼ 1200 before EWs
measurement as our motivation in this work is to evaluate how accurate
stellar parameters can be derived from fairly low-resolution spectra.
The spectral features were corrected for the zero velocity by
shifting. Finally, EWs and their uncertainties are estimated following
the method as described by Newton et al. (2014AJ....147...20N 2014AJ....147...20N, Cat.
J/AJ/147/20). These estimated EWs are used to study the behaviour of
spectral features with stellar parameters in the section 3 Results and
discussion.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 340 177 Stellar parameters and estimated EWs of
the spectral features of our cool giants sample
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See also:
III/45 : Infrared Spectra for 32 Stars (Johnson+ 1970)
J/A+AS/116/239 : H band stellar spectra (Dallier+, 1996)
J/ApJ/508/397 : H-band Spectral Standards (Meyer+ 1998)
J/ApJS/151/387 : Near-IR spectral library of late-type stars (Ivanov+, 2004)
J/ApJS/238/29 : IGRINS spectral library (Park+, 2018)
J/A+A/634/A133 : X-Shooter Spectral Library (XSL). DR2 (Gonneau+, 2020)
J/A+A/627/A138 : XSL atmospheric parameters (Arentsen+, 2019)
J/A+A/641/A44 : Dwarfs, giants and supergiants Equivalent widths
(Morelli+, 2020)
J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)
http://xsl.astro.unistra.fr/ : The X-shooter Spectral Library
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- Name Star name (StarName)
28- 31 I4 K Teff Effective temperature adopted from
Arentsen et al. (2019A&A...627A.138A 2019A&A...627A.138A,
Cat. J/A+A/627/A138) that are derived
using the full-spectrum fits (Teff)
33- 35 I3 K e_Teff Teff uncertainty (TeffE)
37- 41 F5.2 [cm/s2] logg Logarithm of surface gravity adopted
from Arentsen et al.
(2019A&A...627A.138A 2019A&A...627A.138A,
Cat. J/A+A/627/A138) that are derived
using the full-spectrum fits (logg)
43- 46 F4.2 [cm/s2] e_logg logg uncertainty (loggE)
48- 53 F6.3 [Sun] [Fe/H] Logarithm of iron to hydrogen abundance
ratio adopted from Arentsen et al.
(2019A&A...627A.138A 2019A&A...627A.138A,
Cat. J/A+A/627/A138) that are derived
using the full-spectrum fits (Meta)
55- 59 F5.3 [Sun] e_[Fe/H] The [Fe/H] uncertainty (MetaE)
61- 67 F7.4 0.1nm EW(Mg150) Equivalent width of Mg I at 1.50 µm
(Mg150)
69- 73 F5.3 0.1nm e_EW(Mg150) EW(Mg150) uncertainty (Mg150E)
75- 81 F7.4 0.1nm EW(K152) Equivalent width of K I at 1.52 µm
(K152)
83- 87 F5.3 0.1nm e_EW(K152) EW(K152) uncertainty (K152E)
89- 95 F7.4 0.1nm EW(Fe153) Equivalent width of Fe I at 1.53 µm
(Fe153)
97- 101 F5.3 0.1nm e_EW(Fe153) EW(Fe153) uncertainty (Fe153E)
103- 109 F7.4 0.1nm EW(H155) Equivalent width of H I at 1.55 µm
(H155)
111- 115 F5.3 0.1nm e_EW(H155) EW(H155) uncertainty (H155E)
117- 123 F7.4 0.1nm EW(CO156) Equivalent width of 12CO at 1.56 µm
(CO156)
125- 129 F5.3 0.1nm e_EW(CO156) EW(CO156) uncertainty (CO156E)
131- 137 F7.4 0.1nm EW(H157) Equivalent width of H I at 1.57 µm
(H157)
139- 143 F5.3 0.1nm e_EW(H157) EW(H157) uncertainty (H157E)
145- 151 F7.4 0.1nm EW(Mg157) Equivalent width of Mg I at 1.57 µm
(Mg157)
153- 157 F5.3 0.1nm e_EW(Mg157) EW(Mg157) uncertainty (Mg157E)
159- 165 F7.4 0.1nm EW(FeH158) Equivalent width of FeH at 1.58 µm
(FeH158)
167- 171 F5.3 0.1nm e_EW(FeH158) EW(FeH158) uncertainty (FeH158E)
173- 179 F7.4 0.1nm EW(Si159) Equivalent width of Si I at 1.59 µm
(Si159)
181- 185 F5.3 0.1nm e_EW(Si159) EW(Si159) uncertainty (Si159E)
187- 192 F6.4 0.1nm EW(CO160) Equivalent width of 12CO at 1.60 µm
(CO160)
194- 198 F5.3 0.1nm e_EW(CO160) EW(CO160) uncertainty (CO160E)
200- 206 F7.4 0.1nm EW(Fe161) Equivalent width of Fe I at 1.61 µm
(Fe161)
208- 212 F5.3 0.1nm e_EW(Fe161) EW(Fe161) uncertainty (Fe161E)
214- 220 F7.4 0.1nm EW(H161) Equivalent width of H I at 1.61 µm
(H161)
222- 226 F5.3 0.1nm e_EW(H161) EW(H161) uncertainty (H161E)
228- 234 F7.4 0.1nm EW(CO162) Equivalent width of 12CO at 1.62 µm
(CO162)
236- 240 F5.3 0.1nm e_EW(CO162) EW(CO162) uncertainty (CO162E)
242- 248 F7.4 0.1nm EW(FeH162) Equivalent width of FeH at 1.62 µm
(FeH162)
250- 254 F5.3 0.1nm e_EW(FeH162) EW(FeH162) uncertainty (FeH162E)
256- 262 F7.4 0.1nm EW(CO164) Equivalent width of 12CO 1.64 µm
(CO164)
264- 268 F5.3 0.1nm e_EW(CO164) EW(CO164) uncertainty (CO164E)
270- 277 F8.5 0.1nm EW(Fe166) Equivalent width of Fe I at 1.66 µm
(Fe166)
279- 283 F5.3 0.1nm e_EW(Fe166) EW(Fe166) uncertainty (Fe166E)
285- 291 F7.4 0.1nm EW(CO166) Equivalent width of 12CO at 1.66 µm
(CO166)
293- 297 F5.3 0.1nm e_EW(CO166) EW(CO166) uncertainty (CO166E)
299- 305 F7.4 0.1nm EW(Al167) Equivalent width of Al I at 1.67 µm
(Al167)
307- 311 F5.3 0.1nm e_EW(Al167) EW(Al167) uncertainty (Al167E)
313- 320 F8.5 0.1nm EW(H168) Equivalent width of H I at 1.68 µm
(H168)
322- 326 F5.3 0.1nm e_EW(H168) EW(H168) uncertainty (H168E)
328- 334 F7.4 0.1nm EW(COMg171) Equivalent width of 12CO + MgI at
1.71µm (COMg171)
336- 340 F5.3 0.1nm e_EW(COMg171) EW(COMg171) uncertainty (COMg171E)
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 17-Jan-2025