J/A+A/585/A64 New atmospheric parameters of MILES cool stars (Sharma+, 2016)
New atmospheric parameters and spectral interpolator for the MILES cool stars.
Sharma K., Prugniel, P., Singh H.P.
<Astron. Astrophys. 585, A64 (2016)>
=2016A&A...585A..64S 2016A&A...585A..64S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, atmospheres ; Atlases ; Effective temperatures ;
Abundances, [Fe/H]
Keywords: methods: data analysis - techniques: spectroscopic -
stars: fundamental parameters
Abstract:
The full spectrum fitting of stellar spectra against a library of
empirical spectra is a well-established approach to measure the
atmospheric parameters of FGK stars with a high internal consistency.
Extending it towards cooler stars still remains a challenge.
We address this question by improving the MILES interpolator
(Prugniel et al., 2011, Cat. J/A+A/531/A165; hereafter PVK) in the low
effective temperature regime (Teff<4800K). We measure the biases of
the determined parameters with respect to our updated compilation of
parameters. After correcting some systematic effects, we compute a new
interpolator that we finally use to redetermine the atmospheric
parameters homogeneously and assess the biases.
Based on an updated literature compilation, we determine Teff in a
more accurate and unbiased manner compared to those determined with
the original interpolator. The validity range is extended downwards to
about Teff=2900K compared to 3500K previously.
The measured parameters are restricted to the current sub sample of
MILES, and we have shown that they are generally more reliable than
those presented in PVK. But the small discontinuity between the PVK
and new measurements is significant, in particular for Teff, and
should be corrected if one needs to join the two series.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 331 Literature compilation and measured parameters
keeping the metallicity fixed at the cluster
metallicity value for the cluster stars
table7.dat 32 17 Remarkable stars discussed in the paper
table10.dat 65 46 Derived parameters of cluster stars leaving
the metallicity free
table11.dat 37 12 Mean measured metallicities of the clusters
miles_tgm2.fits 2880 853 MILES interpolator FITS file
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See also:
J/A+A/531/A165 : MILES atmospheric parameters (Prugniel+, 2011)
http://ulyss.univ-lyon1.fr/ : ULySS package
Description of file: miles_tgm2.fits
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MILES V2 spectral interpolator
The FITS file is an improved version of MILES interpolator previously
presented in PVK. It contains the coefficients of the interpolator,
which allows one to compute an interpolated spectrum, giving an
effective temperature, log of surface gravity and metallicity (Teff,
logg, and [Fe/H]).
The file consists of three extensions containing the three temperature
regimes described in the paper.
Extension Teff range
0 warm 4000-9000K
1 hot >7000K
2 cold <4550K
The three functions are linearly interpolated in the Teff overlapping
regions.
Each extension contains a 2D image-type array, whose first axis is the
wavelength described by a WCS (Air wavelength, starting at 3536Å,
step=0.9Å). This FITS file can be used by the ULySS v1.3 or higher.
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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- 26 A26 --- Name Designation of the star
30- 32 I03 --- Miles Internal number in MILES
36- 39 I4 K TeffC Compiled effective temperature
43- 47 F5.2 [cm/s2] loggC Compiled log of surface gravity
52- 56 F5.2 [-] [Fe/H]C ?=9.99 Compiled metallicity
60 I1 --- FlagC [0/2] Compilation quality flag (1)
62- 66 I5 K Teff Effective temperature (this work)
68- 71 I4 K e_Teff Error on Teff (this work)
75- 79 F5.2 [cm/s2] logg Log of the surface gravity (this work)
82- 86 F5.2 [cm/s2] e_logg Error on logg (this work)
90- 94 F5.2 [-] [Fe/H] Metallicity (this work) (2)
96-100 F5.2 [-] e_[Fe/H] ?=9.99 Error on [Fe/H] (this work)
103 A1 --- u_[Fe/H] Uncertainty flag on [Fe/H] (3)
106 I1 --- FlagW [0/2] Wavelength consistency flag (4)
109 I1 --- FlagS [0/2] Stability flag (5)
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Note (1): Please refer to Sect. 2 for the detailed definition of compilation
quality flags (0 for the best data and 2 for the poorest).
Note (2): For cluster stars, parameters are computed with fixed [Fe/H] at
cluster metallicity.
Note (3): Unreliable metallicities for the giants cooler than 3800K have been
marked with a colon ':'.
Note (4): Please refer to Sect. 5.1 for wavelength consistency flags. (0 are the
solutions most consistent over the whole wavelength range).
Note (5): Please refer to Sect 5.2 of the paper. (0 flag represents the most
stable).
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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- 26 A26 --- Name Star identification
30- 32 I3 --- Miles Internal MILES number
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 27 A27 --- Name Designation of the cluster star
29- 31 I3 --- Miles Internal MILES number
34- 38 F5.2 [-] [Fe/H]l Cluster [Fe/H] adopted from literature
41- 45 I5 K Teff Derived effective temperature
47- 51 F5.2 [cm/s2] logg Derived log of surface gravity
55- 59 F5.2 [-] [Fe/H] Derived [Fe/H]
61- 65 F5.2 [-] e_[Fe/H] Error on [Fe/H]
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Cluster Name of the cluster
10- 11 I02 --- Nstar Number of stars studied from the cluster
14- 18 F5.2 [-] [Fe/H] Mean measured metallicity
20- 24 F5.2 [-] e_[Fe/H] Mean errors of measured metallicity
26- 30 F5.2 [-] s_[Fe/H] ?=9.99 Dispersion of measured metallicities
for the stars from the same cluster.
33- 37 F5.2 [-] d[Fe/H] Difference between the compiled and mean
measured metallicity
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Acknowledgements:
Kaushal Sharma, kaushalksharma1989(at)gmail.com
(End) Kaushal Shamra [Univ. of Delhi], Patricia Vannier [CDS] 15-Dec-2015