J/ApJS/256/41 Grid of synthetic spectra for subdwarfs (Pacheco+, 2021)
A grid of synthetic spectra for subdwarfs:
Non-LTE line-blanketed atmosphere models.
Pacheco T.A., Diaz M.P., Levenhagen R.S., Coelho P.R.T.
<Astrophys. J. Suppl. Ser. 256, 41 (2021)>
=2021ApJS..256...41P 2021ApJS..256...41P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, subdwarf ; Models ; Spectroscopy
Keywords: stellar atmospheres - spectral energy distribution -
stellar spectral lines - subdwarf stars
Abstract:
A new grid of detailed atmosphere model spectra for hot and moderately
cool subdwarf stars is presented. High-resolution spectra and
synthetic photometry are calculated in the range from 1000Å to
10,000Å using Non-LTE fully line- blanketed atmosphere structures.
Our grid covers eight temperatures within 10000<Teff[K]<65000, three
surface gravities in the range 4.5<logg[cgs]<6.5, two helium
abundances matching two extreme helium-rich and helium-poor scenarios,
and two limiting metallicity boundaries regarding both solar
([Fe/H]=0) and Galactic halo ([Fe/H]=-1.5 and [alpha/Fe]=+0.4).
Besides its application in the determination of fundamental parameters
of subdwarfs in isolation and in binaries, the resulting database is
also of interest for population synthesis procedures in a wide variety
of stellar systems.
Description:
96 spectra in FITS (2-D data) covering wavelength between 1000 and
10000Å with microturbulent velocity = 10km/s and
rotation velocity = 0.
$1 wavelength in angstrom $2 flux in erg/cm2/s/Hz
From filename:
The number after t is Teff and the number after g is log g.
The suffix represents the chemical abundances:
sol_Hepoor ([Fe/H]=0 and He-poor);
sol_Herich ([Fe/H]=0 and He-rich);
lowZ_Hepoor ([Fe/H]=-1.5, [alpha/Fe]=+0.4 and He-poor); or
lowZ_Herich ([Fe/H]=-1.5, [alpha/Fe]=+0.4 and He-rich).
The reference for each He value (log(nHe/nH)) as a function of Teff is
available at paper's table 2 as follow:
10000K: He rich = -3.81 and He poor = -4.98
15000K: He rich = -3.13 and He poor = -4.35
20000K: He rich = -2.46 and He poor = -3.72
25000K: He rich = -1.78 and He poor = -3.09
30000K: He rich = -1.22 and He poor = -2.42
35000K: He rich = -0.43 and He poor = -1.83
45000K: He rich = +0.92 and He poor = -0.57
65000K: He rich = +3.62 and He poor = +1.95
Example: t10000g+4.5sol_Hepoor.spec is the spectrum with
10000K, log g=+4.5, solar abundance and He-poor.
How to read data from python3:
---------------------------------------------------------------------
≫>from astropy.io import fits
≫>hdr = fits.getheader('./t25000g+4.5lowZHepoorhr.fit') #Header
≫>hdl = fits.getdata('./t25000g+4.5lowZHepoorhr.fit') #Data
≫>w = hdl['WAVELENGTH']
≫>f = hdl['FLUX']
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 60 96 List of fits spectra
sp/* . 96 Individual fits spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 31 A31 --- FileName Name of the spectrum file in subdirectory sp
33- 37 I5 K Teff [10000/65000] Effective temperature
39- 42 F4.1 [cm/s2] logg Surface gravity, +4.5, +5.5 or +6.5
44- 47 F4.1 [-] [Fe/H] Metallicity (0 for solar abundance)
49- 52 F4.1 [-] [alpha/Fe] ? [alpha/Fe] abundance
54- 60 A7 --- He He-poor or He-rich (1)
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Note (1): Reference for each He value (log(nHe/nH)) as a function of Teff
as follows:
10000K = He rich = -3.81 and He poor = -4.98
15000K = He rich = -3.13 and He poor = -4.35
20000K = He rich = -2.46 and He poor = -3.72
25000K = He rich = -1.78 and He poor = -3.09
30000K = He rich = -1.22 and He poor = -2.42
35000K = He rich = -0.43 and He poor = -1.83
45000K = He rich = +0.92 and He poor = -0.57
65000K = He rich = +3.62 and He poor = +1.95
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Acknowledgements:
Thayse Pacheco, thayse.pacheco(at)usp.br
(End) Thayse Pacheco [USP, Brazil], Patricia Vannier [CDS] 30-Sep-2021