J/MNRAS/493/871 MEGARA-GTC stellar spectral library I (Garcia-Vargas+, 2020)
MEGARA-GTC stellar spectral library: I.
Garcia-Vargas M.L., Carrasco E., Molla M., Gil de Paz A., Berlanas S.R.,
Cardiel N., Gomez-Alvarez P., Gallego J., Iglesias-Paramo J., Cedazo R.,
Pascual S., Castillo-Morales A., Perez-Calpena A., Martinez-Delgado I.
<Mon. Not. R. Astron. Soc., 493, 871-898 (2020)>
=2020MNRAS.493..871G 2020MNRAS.493..871G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, fundamental ; Spectral types ; Effective temperatures ;
Abundances ; Equivalent widths ; Spectra, optical ;
Photometry, UBVRI
Keywords: atlases - catalogues - stars: abundances -
stars: fundamental parameters - globular clusters: individual: M15
Abstract:
MEGARA (Multi Espectrografo en GTC de Alta Resolucion para Astronomia)
is an optical (3650-9750Å), fibre-fed, medium-high spectral
resolution (R=6000, 12000 and 20000) instrument for the Gran
Telescopio CANARIAS (GTC) 10.4-m telescope, commissioned in the summer
of 2017, and currently in operation. The scientific exploitation of
MEGARA requires a stellar spectra library to interpret galaxy data and
to estimate the contribution of the stellar populations. In this
paper, we introduce the MEGARA-GTC spectral library, detailing the
rationale behind the building of this catalogue. We present the
spectra of 97 stars (21 individual stars and 56 members of the
globular cluster M15, which are both subsamples taken during the
commissioning runs, and 20 stars from our ongoing GTC Open-Time
programme). The spectra have R=20000 in the HR-R and HR-I set-ups,
centred at 6563 and 8633Å, respectively. We describe the procedures
to reduce and analyse the data. Then, we determine the best-fitting
theoretical models to each spectrum through a χ2 minimization
technique, to derive the stellar physical parameters, and we discuss
the results. We have also measured some absorption lines and indices.
Finally, we introduce our project to complete the library and the data
base in order to make the spectra available to the community.
Description:
The MEGARA-GTC basic stellar library currently contains 2983 stars
covering wide ranges in Teff, logg and abundance [M/H]. To define
the catalogue, we made a compilation of observed stars from different
libraries whose main characteristics and references are summarized in
Table 3.
In terms of the spectral region, we have prioritized the library in
HR-R and HR-I (R∼20000) as there are no published empirical catalogues
covering these spectral ranges and resolution even though they are in
great demand.
We present in this paper a subsample of 97 stars that will form part
of the first release of the MEGARA-GTC library. During MEGARA
commissioning at the GTC (2017 June-August), we started a pilot
programme whose goal was to obtain the first observations of the
MEGARA-GTC library using HR-I (see Tables 5, 7 and 11). We also
observed the centre of the M15 cluster in both HR-R and HR-I
configurations, with the MEGARA MOS mode using the robotic
positioners. The results of these observations are presented in Tables
8 and 12. Finally, we include in this paper 20 stars, also observed in
HR-R and HR-I, belonging to the basic library and observed with the
filler GTC programme (see Tables 6, 9, 10 and 11).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 46 18 MEGARA spectral configurations as measured at
the GTC
table3.dat 99 10 Existing stellar libraries used for MEGARA-GTC
library input catalogue
table4.dat 102 10 MEGARA-GTC stellar library catalogue sample
table5.dat 71 21 Subsample of 21 stars observed with the HR-I
spectral configuration during MEGARA
commissioning between 2017 June and August
table6.dat 86 20 Subsample of 20 OT stars observed with HR-R and
HR-I set-ups from the programme 35-GTC22/18B
table7.dat 107 24 Stellar parameters for the 21 commissioning
stars derived from the fitting with the
theoretical models for the HR-I set-up, and
from the literature
table8.dat 75 168 Stellar parameters for the M15 stars derived
from the fit of the theoretical models to the
observed spectra in HR-R and HR-I, and the
simultaneous fitting to the combined spectrum
with HR-R and HR-I
table9.dat 128 20 Stellar parameters for the 20 OT stars derived
from the fitting with the theoretical models
and from the literature for the HR-R and HR-I
separately
table10.dat 88 20 Stellar parameters for the 20 OT stars derived
from the fitting with the combined spectrum of
both HR-R and HR-I set-ups
table11.dat 153 41 Equivalent widths of the CaII, MgI and Pa lines,
and sTiO colour for the subsample of 21 COM
stars observed in HR-I and the 20 stars of the
OT subsample
table12.dat 153 56 Equivalent widths of the CaII, MgI and Pa lines,
and sTiO colour for the 56 stars in the M15
subsample observed in HR-I during MEGARA
commissioning
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See also:
J/MNRAS/326/959 : Empirical calibration of the near-IR Ca triplet
(Cenarro+ 2001)
J/MNRAS/396/1895 : MgI and sTiO index definitions (Cenarro+, 2009)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- VPH Set-up or name of the volume phase
holographic (VPH) gratings
7- 12 F6.1 0.1nm lmin1 Shortest wavelength of the central fibre
spectrum
14- 19 F6.1 0.1nm lmin Shortest wavelength common to all spectra
21- 26 F6.1 0.1nm lc Central wavelength
28- 33 F6.1 0.1nm lmax Longest wavelength for all spectra
35- 40 F6.1 0.1nm lmax1 Longest wavelength of the central fibre
spectrum
42- 46 F5.3 0.1nm/pix Disp Constant linear reciprocal dispersion
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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- 11 A11 --- Library Name of the library
13- 17 I5 --- Res Resolving power
19- 22 I4 --- lambdamin Spectral range (minimum wavelength value)
24- 28 I5 --- lambdamax Spectral range (maximum wavelength value)
30- 33 I4 --- Nstars Number of stars
35- 36 A2 --- set-up [LR/MR/HR] MEGARA set-up (1)
38- 99 A62 --- Ref Reference
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Note (1): MEGARA set-up as follows:
LR = Low resolution mode
MR = Medium resolution mode
HR = High resolution mode
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name (HD NNNNNN)
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 20 F4.1 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 32 F4.1 arcsec DEs Declination (J2000)
34- 41 F8.3 mas/yr pmRA Proper motion in right ascension
43- 51 F9.3 mas/yr pmDE Proper motion in declination
53- 59 A7 --- SpType Spectral type and luminosity class
61- 63 F3.1 mag Vmag Johnson V-band magnitude
65- 67 F3.1 mag Rmag ? Johnson R-band magnitude
69- 71 F3.1 mag Imag ? Johnson I-band magnitude
73- 75 F3.1 mag Jmag ? Johnson J-band magnitude5
77- 80 I4 K Teff ? Effective temperature
82- 85 F4.2 [cm/s2] logg ? Surface gravity
87- 91 F5.2 [-] [M/H] ? Metallicity
93-102 A10 --- Library Name of the library
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 25 A14 --- SpType Spectral type and luminosity class
27- 30 F4.1 mag Umag ? Johnson U-band magnitude
32- 35 F4.1 mag Bmag Johnson B-band magnitude
37- 40 F4.1 mag Vmag Johnson V-band magnitude
42- 45 F4.1 mag Rmag ? Johnson R-band magnitude
47- 50 F4.1 mag Imag ? Johnson I-band magnitude
52- 61 A10 "Y:M:D" Date Observation date
63- 71 A9 s ExpTime Exposure time
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 20 A9 --- SpType Spectral type and luminosity class
22- 24 F3.1 --- Umag ? Johnson U-band magnitude
26- 29 F4.1 --- Bmag Johnson B-band magnitude
31- 34 F4.1 --- Vmag Johnson V-band magnitude
36- 38 F3.1 --- Rmag ? Johnson R-band magnitude
40- 42 F3.1 --- Imag ? Johnson I-band magnitude
44- 51 A8 "Y:M:D" Date Observation date
53- 56 A4 s ExpTimeR Exposure time for HR-R set-up
58- 61 A4 s ExpTimeI Exposure time for HR-I set-up
63- 67 I5 K Teff Effective temperature
69- 72 F4.2 [cm/s2] logg Surface gravity
74- 78 A5 [-] [Fe/H] Fe/H abundance ratio
80- 86 A7 --- Library Name of the library
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 15 F4.2 --- chi2min Minimum χ2 value
17- 21 F5.3 --- Pmax Maximum probability associated with chi2min
23- 27 I5 K Teff Effective temperature corresponding the
minimum χ2 value
29- 31 F3.1 [cm/s2] logg Surface gravity corresponding the minimum
χ2 value
33- 36 F4.1 [-] [M/H] Metallicity corresponding the minimum
χ2 value
38- 40 I3 --- N Number of models
42- 46 I5 K Teffmean Average effective temperature of the set of
N models
48- 51 I4 K e_Teffmean Error on Teffmean
53- 56 F4.2 [cm/s2] loggmean Average surface gravity of the set of N
models
58- 61 F4.2 [cm/s2] e_loggmean Error on loggmean
63- 67 F5.2 [-] [M/H]mean Average metallicity of the set of N models
69- 72 F4.2 [-] e_[M/H]mean Error on [M/H]mean
74- 78 I5 K Tefflit ? Effective temperature from literature
80- 82 I3 K e_Tefflit ? Error on Tefflit
84- 87 F4.2 [cm/s2] logglit ? Surface gravity from literature
89- 92 F4.2 [cm/s2] e_logglit ? Error on logglit
94- 98 F5.2 [-] [M/H]lit ? Metallicity from literature
100-103 F4.2 [-] e_[M/H]lit ? Error on [M/H]lit
105-107 A3 --- Ref Reference (1)
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Note (1): Reference as follows:
1 = Cenarro et al. (2001MNRAS.326..981C 2001MNRAS.326..981C)
2 = Chen et al. (2014ASInC..11...17C 2014ASInC..11...17C)
3 = Prugniel & Soubiran (2004astro.ph..9214P 2004astro.ph..9214P)
4 = Prugniel, Vauglin & Koleva (2011A&A...531A.165P 2011A&A...531A.165P, Cat. J/A+A/531/A165)
5 = Cameron (2003AJ....125.2531R 2003AJ....125.2531R, Cat. V/125)
6 = Valdes et al. (2004ApJS..152..251V 2004ApJS..152..251V, Cat. J/ApJS/152/251)
7 = Holgado et al. (in preparation)
8 = Blomme et al. (2013A&A...550A..90B 2013A&A...550A..90B)
9 = Martins, Schaerer & Hillier (2005A&A...436.1049M 2005A&A...436.1049M)
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Spectra Observed spectra (HR-R, HR-I or the
combined spectrum using both HR-R and HR-I)
11- 12 I2 --- ID [1/56] Internal star identifier
14- 20 F7.3 --- chi2min Minimum χ2 value
22- 25 F4.2 --- Pmax Maximum probability associated with chi2min
27- 30 I4 K Teff Effective temperature corresponding the
minimum χ2 value
32- 34 F3.1 [cm/s2] logg Surface gravity corresponding the minimum
χ2 value
36- 40 F5.2 [-] [M/H] Metallicity corresponding the minimum
χ2 value
42- 44 I3 --- N Number of models
46- 49 I4 K Teffmean Average effective temperature of the set of
N models
51- 54 I4 K e_Teffmean Error on Teffmean
56- 59 F4.2 [cm/s2] loggmean Average surface gravity of the set of N
models
61- 64 F4.2 [cm/s2] e_loggmean Error on loggmean
66- 70 F5.2 [-] [M/H]mean Average metallicity of the set of N models
72- 75 F4.2 [-] e_[M/H]mean Error on [M/H]mean
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 16 F5.3 --- chi2minR Minimum χ2 value for HR-R spectra
18- 21 F4.2 --- PmaxR Maximum probability associated with
chi2min for HR-R spectra
23- 26 I4 K TeffR Effective temperature corresponding the
minimum χ2 value for HR-R spectra
28- 30 F3.1 [cm/s2] loggR Surface gravity corresponding the minimum
χ2 value for HR-R spectra
32- 35 F4.1 [-] [M/H]R Metallicity corresponding the minimum
χ2 value for HR-R spectra
37- 39 I3 --- NR Number of models for HR-R spectra
41- 44 I4 K TeffmeanR Average effective temperature of the set
of N models for HR-R spectra
46- 49 I4 K e_TeffmeanR Error on TeffmeanR
51- 53 F3.1 [cm/s2] loggmeanR Average surface gravity of the set of N
models for HR-R spectra
55- 57 F3.1 [cm/s2] e_loggmeanR Error on loggmeanR
59- 63 F5.2 [-] [M/H]meanR Average metallicity of the set of N models
for HR-R spectra
65- 68 F4.2 [-] e_[M/H]meanR Error on [M/H]meanR
70- 74 F5.3 --- chi2minI Minimum χ2 value for HR-I spectra
76- 79 F4.2 --- PmaxI Maximum probability associated with
chi2min for HR-I spectra
81- 85 I5 K TeffI Effective temperature corresponding the
minimum χ2 value for HR-I spectra
87- 89 F3.1 [cm/s2] loggI Surface gravity corresponding the minimum
χ2 value for HR-I spectra
91- 94 F4.1 [-] [M/H]I Metallicity corresponding the minimum
χ2 value for HR-I spectra
96- 98 I3 --- NI Number of models for HR-I spectra
100-104 I5 K TeffmeanI Average effective temperature of the set
of N models for HR-I spectra
106-109 I4 K e_TeffmeanI Error on TeffmeanI
111-113 F3.1 [cm/s2] loggmeanI Average surface gravity of the set of N
models for HR-I spectra
115-117 F3.1 [cm/s2] e_loggmeanI Error on loggmeanI
119-123 F5.2 [-] [M/H]meanI Average metallicity of the set of N
models for HR-I spectra
125-128 F4.2 [-] e_[M/H]meanI Error on [M/H]meanI
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 16 F5.3 --- chi2min Minimum χ2 value
18- 21 F4.2 --- Pmax Maximum probability associated with chi2min
23- 26 I4 K Teff Effective temperature corresponding the
minimum χ2 value
28- 30 F3.1 [cm/s2] logg Surface gravity corresponding the minimum
χ2 value
32- 35 F4.1 [-] [M/H] Metallicity corresponding the minimum
χ2 value
37- 38 I2 --- N Number of models
40- 43 I4 K Teffmean Average effective temperature of the set of
N models
45- 47 I3 K e_Teffmean Error on Teffmean
49- 51 F3.1 [cm/s2] loggmean Average surface gravity of the set of N
models
53- 55 F3.1 [cm/s2] e_loggmean Error on loggmean
57- 61 F5.2 [-] [M/H]mean Average metallicity of the set of N models
63- 66 F4.2 [-] e_[M/H]mean Error on [M/H]mean
68- 72 I5 K Tefflit Effective temperature from literature
74- 76 F3.1 [cm/s2] logglit Surface gravity from literature
78- 82 F5.2 [-] [M/H]lit Metallicity from literature
84- 88 I5 --- Res Resolving power of the spectra
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Byte-by-byte Description of file: table11.dat table12.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 14 I3 --- S/N Continuum S/N averaged over the whole
spectrum as defined by Stoehr et al.
(2008ASPC..394..505S 2008ASPC..394..505S)
16- 21 F6.3 0.1nm Ca1CEN Equivalent width of the CaII 8498.03Å
line (1)
23- 27 F5.3 0.1nm e_Ca1CEN Error on Ca1CEN
29- 34 F6.3 0.1nm Ca2CEN Equivalent width of the CaII 8542.09Å
line (1)
36- 40 F5.3 0.1nm e_Ca2CEN Error on Ca2CEN
42- 47 F6.3 0.1nm Ca3CEN Equivalent width of the CaII 8662.14Å
line (1)
49- 53 F5.3 0.1nm e_Ca3CEN Error on Ca3CEN
55- 60 F6.3 0.1nm MgI Equivalent width of the MgI 8806.76Å
line (1)
62- 66 F5.3 0.1nm e_MgI Error on MgI
68- 73 F6.3 0.1nm Pa1 Equivalent width of the Paschen 8467.3Å
line (1)
75- 79 F5.3 0.1nm e_Pa1 Error on Pa1
81- 86 F6.3 0.1nm Pa2 Equivalent width of the Paschen 8598.4Å
line (1)
88- 93 F6.3 0.1nm e_Pa2 Error on Pa2
95-100 F6.3 0.1nm Pa3 Equivalent width of the Paschen 8750.5Å
line (1)
102-107 F6.3 0.1nm e_Pa3 Error on Pa3
109-114 F6.3 0.1nm Ca1MEG Equivalent width of the CaII 8498.03Å
line using the new windows defined in this
paper (2)
116-120 F5.3 0.1nm e_Ca1MEG Error on Ca1MEG
122-127 F6.3 0.1nm Ca2MEG Equivalent width of the CaII 8542.09Å
line using the new windows defined in this
paper (2)
129-133 F5.3 0.1nm e_Ca2MEG Error on Ca2MEG
135-140 F6.3 0.1nm Ca3MEG Equivalent width of the CaII 8662.14Å
line using the new windows defined in this
paper (2)
142-146 F5.3 0.1nm e_Ca3MEG Error on Ca3MEG
148-153 F6.3 0.1nm sTiO sTiO colour as defined by Cenarro et al.
(2009MNRAS.396.1895C 2009MNRAS.396.1895C,
Cat. J/MNRAS/396/1895)
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Note (1): Equivalent widths measured using Cenarro et al. (2001MNRAS.326..959C 2001MNRAS.326..959C,
Cat. J/MNRAS/326/959) windows
Note (2): The new proposed continuum windows for CaII lines are, for Ca1 and
Ca2 lines, 8450.0-8460.0Å (blue) and 8565.5-8575.0Å (red), while
for Ca3 we use 8619.5-8642.5Å (blue) and 8700.5-8710.0Å (red).
The feature windows are 8482.0-8512.0Å (Ca1), 8531.0-8554.0Å
(Ca2) and 8650.0-8673.0Å (Ca3).
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 31-Mar-2023