Grid of 1D helium-rich LTE synthetic spectra

Separate files for log (g) = 7.0, 7.5, 8.0, 8.5, 9,0
Each file includes temperatures from 2000 (3500 pure pure-He) to 40,000 K.
Composition (y = He/H) is from pure-He (y=1e30), to 1e8, 1e5 and 1e2

Convection model is 1D ML2/alpha = 1.25.

File format:

 1) Grid of 2711 wavelength points in Angstrom
 2) For each model at fixed gravity
    Header
    "Effective temperature =   [value]  gravity =  [value]  y =  1.000E+30"
    Grid of 2711 Fnu Eddington fluxes in air wavelength 
    (units of erg cm^-2 s^-1 Hz^-1)

Main reference
Cukanovaite, E., Tremblay, P.-E., Bergeron, P., et al. (2021) MNRAS, 501, 5274.

Conversion:

The flux at Earth is f = 4*pi*R^2/D^2 * Eddington flux

where R is the white dwarf radius, D the distance and the Eddington flux 
the quantity in the files. The radius can be found from Evolutionary Sequences.
There are several sources including the website below
https://www.astro.umontreal.ca/~bergeron/CoolingModels/

For spectroscopic fitting 3D corrections should be added for accurate atmospheric parameters. For photometric fitting 1D models are sufficient. The link below provides 3D correction functions as a Python code.

Main reference (3D corrections)
Cukanovaite, E., Tremblay, P.-E., Bergeron, P. et al. (2021) MNRAS, 501, 5274.

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Physics included in the calculations:

Convection model is 1D ML2/alpha = 1.25
Cukanovaite, E., Tremblay, P.-E., Bergeron, P., et al. (2021) MNRAS, 501, 5274.

Non-ideal effects from charged and neutral particles 
Hummer, D.G. and Mihalas, D. 1988, ApJ, 331, 794
(Bohr radii of H I, H2, He II and He III have a free parameter of 0.5;
see Tremblay et al. 2010, ApJ, 712, 1345; Cukanovaite et al. 2021 MNRAS, 501, 5274)
Non-ideal effects on ionisation potentials are excluded from this version because
the HM88 thoery is thought to be unreliable at densities where partial degeneracy
is important. It means that the fraction of free electrons is the same as that of an
ideal gas. Non-ideal effects are still included for individual population levels.

Lyman, Balmer, Paschen, Brackett lines profiles (extended to a total of 60 lines in 2015)
Tremblay, P.-E. & Bergeron, P. (2009) ApJ, 696, 1755

Hydrogen neutral broadening profiles for Lyman alpha, beta, gamma and delta
Allard, N. 2014, public website (https://www.iap.fr/useriap/allard/lymantables.html)
Broadening due to charged particles for these lines is treated from the Tremblay+2009 reference above.

Hydrogen neutral broadening profiles for Lyman alpha from H2-H and H-H collisions
Kowalski, P. M., Saumon D. 2006, ApJ, 651, L137
(Warning: H-He collisions are not included)

H2 collision-induced absorption (including high-density corrections from Hare & Welsh 1958)
H2-H2 from Borysow et al. (2001, JQSRT, 68, 235)
H2-H from Hitran database (http://hitran.org/cia/)
H2-He from Jorgensen et al. (2000, A&A, 361, 283)
H-He from Gustafsson et al. (2001, APJ, 546, 1168)

H minus bf and ff opacity
John, T. L. 1988, A&A, 193, 189

He I bf, He II bf, He II ff, He III ff, He minus
Beauchamp A., 1995, PhD thesis

He I Stark broadening
Beauchamp A., 1995, PhD thesis (Stark broadening)

He I neutral broadening
Unsöld (1955) Physik der Sternatmospharen
Cukanovaite, E., Tremblay, P.-E., Bergeron, P., et al. (2021) MNRAS, 501, 5274.

He2+ bf and ff opacity
Stancil 1994, JQSRT, 51, 655

H2 minus ff opacity
H2+ bf and ff opacity
H bf opacity (>972 Angstrom Hummer & Mihalas pseudo-continuum cut)
H, H2 and H3 ff opacity
Stimulated emission
H, H2, He I, He II Rayleigh scattering
(Standard references, e.g. Mihalas 1978 Stellar Atmospheres book and Kurucz 1970, Atlas: A Computer Program)