J/MNRAS/493/4533 NIR spectroscopic study of young M dwarfs (Khata+, 2020)
Understanding the physical properties of young M dwarfs: NIR spectroscopic
studies.
Khata D., Mondal S., Das R., Ghosh S., Ghosh S.
<Mon. Not. R. Astron. Soc., 493, 4533-4550 (2020)>
=2020MNRAS.493.4533K 2020MNRAS.493.4533K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, dwarfs ; Stars, fundamental ;
Equivalent widths ; Effective temperatures ; Stars, masses ;
Stars, diameters ; Spectral types ; Spectra, infrared
Keywords: methods: observational - techniques: spectroscopic -
stars: fundamental parameters - stars: low-mass - infrared: stars
Abstract:
We present here medium resolution (λ/Δλ∼1200) H-
and K-band spectra of M-type dwarf stars covering the wavelength
ranges 1.50-1.80µm and 1.95-2.45µm. The sample includes 53 dwarf
stars (M0V-M7V) from new observations using the TIFR Near-Infrared
Spectrometer and Imager instrument on the 2-m Himalayan Chandra
Telescope. Using interferometrically measured effective temperature
(Teff), radius and luminosity of nearby bright calibrator stars, we
have created new empirical relationships among those fundamental
parameters and spectral indices. The equivalent widths of H-band
spectral features like Mg (1.57µm), Al (1.67µm) and Mg
(1.71µm), and the H2O-H index are found to be good indicators of
Teff, radius and luminosity and we establish linear functions using
these features relating to those stellar parameters. The
root-mean-squared error of our best fits are 102K, 0.027R☉ and
0.12dex respectively. Using spectral-type standards along with known
parallaxes, we calibrate both H- and K-band H2O indices as a tracer
of spectral type and absolute Ks magnitude. Metallicities of M-dwarf
samples are estimated using the K-band calibration relationships. The
masses of M dwarfs could be determined using the luminosity
(L/L☉) and we establish a new empirical relation for this. We
also compare and contrast our results with other similar work from the
literature.
Description:
In this paper, we present H- (1.50-1.84um) and K- (1.95-2.45um) band
spectra of 53 M dwarfs including seven stars with interferometric
radius, nine objects with reliable metallicity estimates (SPOCS I
catalogue) and 10 possible planet candidates; almost half of our
sample is in the northern 8pc region. We measured the EWs and H2O
index in both the H and K bands and determined spectroscopic Teff,
radius, luminosity, spectral type, absolute Ks magnitude,
metallicity and mass by deriving empirical calibration relations for
these parameters (all the estimated parameters are given in Table 9).
The estimation of our spectral properties is mostly model-independent.
The observations were performed using the medium-resolution TIRSPEC
instrument on the 2-m HCT at Hanle, India over 10 nights during
different observing cycles from 2016-2018. Due to limited observing
nights we preferably tried to select nearby bright (K-mag within 8.0)
objects so that we could observe using 100s exposure in multiple
frames to cover the spectral ranges up to M7V.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 53 Log of H- and K-band spectroscopic observations
using 2-m HCT and observational properties of
M dwarfs
table2.dat 95 53 Estimation of EWs and H2O indices in the H
and K bands for the TIRSPEC M-dwarf samples
table3.dat 57 5 Spectral features and continuum points
table4.dat 84 12 Inferred Teff, radius and Lbol for the
calibration samples
table5.dat 35 15 M-dwarf spectral-type calibration samples
table6.dat 28 16 List of objects used as calibrators to estimate
Mk
table7.dat 38 12 M-dwarf metallicity calibration samples
table8.dat 39 12 Mass calibration samples
table9.dat 108 53 Estimated stellar parameters for our observed
(2-m HCT) M dwarfs
tablea1.dat 28 16 EW of MgI (1.57um) for the BT-Settl model
spectra
tablea2.dat 28 16 EW of Al-a (1.67um) for the BT-Settl model
spectra
tablea3.dat 28 16 EW of MgI (1.71um) for the BT-Settl model
spectra
tablea4.dat 28 16 EW of NaI (2.21um) for the BT-Settl model
spectra
tablea5.dat 28 16 EW of CaI (2.26um) for the BT-Settl model
spectra
tablea6.dat 28 16 H-band H2O index for the BT-Settl model
spectra
tablea7.dat 28 16 K-band H2O index for the BT-Settl model
spectra
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 20 A9 --- f_Name Flag on Name (1)
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 32 F5.2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 45 F5.2 arcsec DEs Declination (J2000)
47- 57 A11 --- Date Observation date
59- 63 F5.3 mag Ksmag 2MASS Ks-band magnitude
65- 67 I3 s ExpTime Exposure time
69- 70 I2 --- Nframe Number of frames
72- 74 I3 --- SNRH Signal to noise ratio on the H-band
76- 78 I3 --- SNRK Signal to noise ratio on the K-band
80- 102 A23 --- Type Star type
104 I1 --- r_Type Reference for Type (2)
106- 124 A19 --- Weather Weather conditions
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Note (1): Flag as follows:
a = M-dwarf Teff, radius and Lbol calibration samples (see Table 4)
b = M-dwarf spectral-type calibration samples (see Table 5)
c = M-dwarf Mk calibration samples (see Table 6)
d = M-dwarf metallicity calibration samples (see Table 7)
e = M-dwarf mass calibration samples (see Table 8)
Note (2): References as follows:
1 = [GKL99] Gershberg et al. (1999A&AS..139..555G 1999A&AS..139..555G, Cat. J/A+AS/139/555)
2 = Frith et al. (2013MNRAS.435.2161F 2013MNRAS.435.2161F, Cat. J/MNRAS/435/2161)
3 = Tokovinin (1997A&AS..124...75T 1997A&AS..124...75T, Cat. J/A+AS/124/75)
4 = Samus et al. (2002AstL...28..174S 2002AstL...28..174S, Cat. J/PAZh/28/201)
5 = Terrien et al. (2015ApJS..220...16T 2015ApJS..220...16T, Cat. J/ApJS/220/16)
6 = Lopez-Morales (2007ApJ...660..732L 2007ApJ...660..732L)
7 = Gagne et al. (2015ApJS..219...33G 2015ApJS..219...33G, Cat. J/ApJS/219/33)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 16 F5.3 0.1nm EW1.57 ? Equivalent width of the 1.57um MgI line
18- 22 F5.3 0.1nm e_EW1.57 ? Error on EW1.57
24- 28 F5.3 0.1nm EW1.67 ? Equivalent width of the 1.67um Al-a line
30- 34 F5.3 0.1nm e_EW1.67 ? Error on EW1.67
36- 40 F5.3 0.1nm EW1.71 ? Equivalent width of the 1.71um MgI line
42- 46 F5.3 0.1nm e_EW1.71 ? Error on EW1.71
48- 52 F5.3 --- H2O-H H-band water index
54- 58 F5.3 --- e_H2O-H Error on H2O-H
60- 65 F6.3 0.1nm EW2.21 Equivalent width of the 2.21um NaI line
67- 71 F5.3 0.1nm e_EW2.21 Error on EW2.21
73- 77 F5.3 0.1nm EW2.26 ? Equivalent width of the 2.26um CaI line
79- 83 F5.3 0.1nm e_EW2.26 ? Error on EW2.26
85- 89 F5.3 --- H2O-K K-band water index
91- 95 F5.3 --- e_H2O-K Error on H2O-K
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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- 13 A13 --- Feature Spectral feature
15 A1 --- Ref [ab] Reference of the given wavelengths (1)
17- 22 F6.4 um windmin Feature window (minimum wavelength) (2)
24- 29 F6.4 um windmax Feature window (maximum wavelength) (2)
31- 36 F6.4 um bluemin Blue continuum (minimum wavelength) (2)
38- 43 F6.4 um bluemax Blue continuum (maximum wavelength) (2)
45- 50 F6.4 um redmin Red continuum (minimum wavelength) (2)
52- 57 F6.4 um redmax Red continuum (maximum wavelength) (2)
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Note (1): Reference as follows:
a = Newton et al. (2015ApJ...800...85N 2015ApJ...800...85N, Cat. J/ApJ/800/85)
b = Rojas-Ayala et al. (2012ApJ...748...93R 2012ApJ...748...93R, Cat. J/ApJ/748/93)
Note (2): Wavelengths are given in vacuum
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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- 9 A9 --- Name Star name
11 A1 --- f_Name [ab] Flag on Name (1)
13- 16 I4 K Teffm Measured effective temperature
18- 19 I2 K e_Teffm Error on Teffm
21- 25 F5.3 Rsun Radm Measured star radius
27- 32 F6.4 Rsun e_Radm Error on Radm
34- 40 F7.4 [Lsun] logLbolm ? Logarithm of the measured bolometric
luminosity
42- 47 F6.4 [Lsun] e_logLbolm ? Error on logLbolm
49- 55 F7.2 K Teffi Inferred effective temperature (G1)
57- 59 I3 K e_Teffi Error on Teffi
61- 65 F5.3 Rsun Radi Inferred star radius (G2)
67- 71 F5.3 Rsun e_Radi Error on Radi
73- 78 F6.3 [Lsun] logLboli ? Logarithm of the measured bolometric
luminosity (G3)
80- 84 F5.3 [Lsun] e_logLboli ? Error on logLboli
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Note (1): Flag as follows:
a = Interferometrically measured parameters taken from table 3 of
Newton et al. (2015ApJ...800...85N 2015ApJ...800...85N, Cat. J/ApJ/800/85)
b = Parameters are from Mann et al. (2015ApJ...804...64M 2015ApJ...804...64M, Cat. J/ApJ/804/64)
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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- 9 A9 --- Name Star name
11- 15 F5.3 --- H2O-H H-band water index
17- 21 F5.3 --- H2O-K K-band water index
23- 26 A4 --- SpTypei Spectral type inferred from the water indices
28- 31 A4 --- SpTypes Spectral type from the Palomar/MSU nearby star
spectroscopic survey
33- 35 A3 --- r_SpTypei Reference used to establish the calibration
relation (1)
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Note (1): Reference as follows:
a = KHM spectral standards (Kirkpatrick et al. 1991ApJS...77..417K 1991ApJS...77..417K,
1995AJ....109..797K 1995AJ....109..797K, 1999ApJ...519..802K 1999ApJ...519..802K)
b = CARMENES input catalogue of M dwarfs (Alonso-Floriano et al.
2015A&A...577A.128A 2015A&A...577A.128A, Cat. J/A+A/577/A128)
c = CARMENES M-dwarf velocities (Reiners et al. 2018A&A...609L...5R 2018A&A...609L...5R,
Cat. J/A+A/609/L5)
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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- 9 A9 --- Name Star name
11- 15 F5.3 mag Ksmag 2MASS Ks-band magnitude
17- 22 F6.2 mas plx Parallax (1)
24- 28 F5.3 mag KsMAG Absolute Ks-band magnitude (G4)
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Note (1): References for the parallaxes are Gaia Collaboration et al.
(2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345), Van Leeuwen (2007A&A...474..653V 2007A&A...474..653V,
Cat. I/311), Henry et al. (2006AJ....132.2360H 2006AJ....132.2360H), Gatewood
(2008AJ....136..452G 2008AJ....136..452G, Cat. J/AJ/136/452), Dittmann et al.
(2014ApJ...784..156D 2014ApJ...784..156D, Cat. J/ApJ/784/156)
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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- 9 A9 --- Name Star name
11- 14 A4 --- SpType Spectral type
16- 20 F5.2 [-] [Fe/H] Fe/H abundance ratio from the SPOCS I catalogue
22- 26 F5.2 [-] [M/H] ? Total metallicity from the SPOCS I catalogue
28- 32 F5.2 [-] [Fe/H]p Predicted Fe/H abundance ratio
34- 38 F5.2 [-] [M/H]p ? Predicted total metallicity
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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 --- Name Star name
11- 15 F5.3 Msun Mstar Star mass
17- 21 F5.3 Msun e_Mstar Error on Mstar
23- 29 F7.5 Lsun Lstar Star luminosity
31- 37 F7.5 Lsun e_Lstar Error on Lstar
39 A1 --- Ref [ab] Reference (1)
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Note (1): Reference as follows:
a = Mann et al. (2013AJ....145...52M 2013AJ....145...52M, Cat. J/AJ/145/52)
b = Mann et al. (2015ApJ...804...64M 2015ApJ...804...64M, Cat. J/ApJ/804/64)
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 15 A4 --- SpType Spectral type (1)
17- 20 I4 K Teff ? Effective temperature (G1)
22- 24 I3 K e_Teff ? Error on Teff
26- 30 F5.3 Rsun Rad ? Star radius (G2)
32- 36 F5.3 Rsun e_Rad ? Error on Rad
38- 43 F6.3 [Lsun] logL ? Logarithm of the star luminosity (G3)
45- 49 F5.3 [Lsun] e_logL ? Error on logL
51- 55 F5.3 Msun Mass ? Stellar mass (2)
57- 61 F5.3 Msun e_Mass ? Error on Mass
63- 68 F6.3 mag KsMAG Absolute Ks-band magnitude (G4)
70- 74 F5.3 mag e_KsMAG Error on KsMAG
76- 81 F6.3 pc Dist Spectroscopic distance (3)
83- 86 F4.2 pc e_Dist Error on Dist
88- 92 F5.2 [-] [M/H] ? Total metallicity (4)
94- 97 F4.2 [-] e_[M/H] ? Error on [M/H]
99- 103 F5.2 [-] [Fe/H] ? Fe/H abundance ratio (4)
105- 108 F4.2 [-] e_[Fe/H] ? Error on [M/H]
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Note (1): Spectral types are calculated using equation 7 with errors of the
order of roughly ±0.7subtypes:
SpNIR=21.68-3.45(H2O-H)-17.76(H2O-K)
Note (2): Stellar mass is measured using the mass-luminosity equation 24:
M=0.0899+24.704L-694.63L2+11202.4L3-67773.4L4
Note (3): Spectroscopic distance is calculated using estimated absolute K
magnitude and photometrically determined apparent magnitude while
ignoring the extinction effects
Note (4): [Fe/H] and [M/H] are calculated using equations 12 and 13 of the
article respectively:
[Fe/H]=-0.571+0.094EWNaI/(H2O-K)+0.007EWCaI/(H2O-K)
[M/H]=-1.143+0.096EWNaI/(H2O-K)+0.139EWCaI/(H2O-K)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 0.1nm EW1 ? Equivalent width of the MgI (1.57um) feature
for logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 0.1nm EW2 ? Equivalent width of the MgI (1.57um) feature
for logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 0.1nm EW3 ? Equivalent width of the MgI (1.57um) feature
for logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 0.1nm EW4 ? Equivalent width of the MgI (1.57um) feature
for logg=5.0 and [Fe/H]=0.5
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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- 4 I4 K Teff Effective temperature
6- 10 F5.3 0.1nm EW1 Equivalent width of the Al-a (1.67um) feature for
logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 0.1nm EW2 Equivalent width of the Al-a (1.67um) feature for
logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 0.1nm EW3 Equivalent width of the Al-a (1.67um) feature for
logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 0.1nm EW4 Equivalent width of the Al-a (1.67um) feature for
logg=5.0 and [Fe/H]=0.5
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 0.1nm EW1 ? Equivalent width of the MgI (1.71um) feature
for logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 0.1nm EW2 ? Equivalent width of the MgI (1.71um) feature
for logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 0.1nm EW3 ? Equivalent width of the MgI (1.71um) feature
for logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 0.1nm EW4 ? Equivalent width of the MgI (1.71um) feature
for logg=5.0 and [Fe/H]=0.5
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 0.1nm EW1 Equivalent width of the NaI (2.21um) feature for
logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 0.1nm EW2 Equivalent width of the NaI (2.21um) feature for
logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 0.1nm EW3 ? Equivalent width of the NaI (2.21um) feature
for logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 0.1nm EW4 Equivalent width of the NaI (2.21um) feature for
logg=5.0 and [Fe/H]=0.5
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 0.1nm EW1 ? Equivalent width of the CaI (2.26um) feature
for logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 0.1nm EW2 Equivalent width of the CaI (2.26um) feature for
logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 0.1nm EW3 ? Equivalent width of the CaI (2.26um) feature
for logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 0.1nm EW4 Equivalent width of the CaI (2.26um) feature for
logg=5.0 and [Fe/H]=0.5
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Byte-by-byte Description of file: tablea6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 --- H2O-H1 H-band water index for logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 --- H2O-H2 H-band water index for logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 --- H2O-H3 H-band water index for logg=5.0 and [Fe/H]=0.0
24- 28 F5.3 --- H2O-H4 H-band water index for logg=5.0 and [Fe/H]=0.5
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Byte-by-byte Description of file: tablea7.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 10 F5.3 --- H2O-K1 K-band water index for logg=4.5 and [Fe/H]=0.0
12- 16 F5.3 --- H2O-K2 K-band water index for logg=4.5 and [Fe/H]=-0.5
18- 22 F5.3 --- H2O-K3 ? K-band water index for logg=5.0 and
[Fe/H]=0.0
24- 28 F5.3 --- H2O-K4 K-band water index for logg=5.0 and [Fe/H]=0.5
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Global Notes:
Note (G1): Teff is inferred using equation 4:
Teff=592.94-364.34Al-a(1.67um)+224.07Mg(1.57um)+2936.78(H2O-H)
Note (G2): Radius is inferred using equation 5:
R=-0.854+0.119Mg(1.57um)-0.150Al-a(1.67um)-0.004Mg(1.57um)/
Al-a(1.67um)+1.203(H2O-H)
Note (G3): Luminosity is inferred using equation 6:
logL=-2.888+0.316Mg(1.71um)-0.101[Mg(1.71um)]2+0.379Mg(1.57um)
Note (G4): The absolute Ks-band magnitude is estimated using equation 8:
KsMAG=17.74+5.76(H2O-H)-17.99(H2O-K2)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 03-May-2023