MSG Grid Files

Multidimensional Spectral Grids (MSG) is a software package for interpolating spectra and colors in pre-computed grids. Due to their large size and gradually evolving content (as improvements are made), grid data files files are not shipped as part of the MSG git repository; rather, they are hosted separately on this page.

• OSTAR2002 Grids
• BSTAR2006 Grids
• C3K Grids
• CAP18 Grids
• Coelho14 Grids
• Göttingen Grids
  • Alpha-dependent Grids
  • Solar-alpha Grids
• SPHINX Grids
• BT-Settl Grids
• NewEra Grids
  • Alpha-dependent Grids
  • Solar-alpha Grids

OSTAR2002 Grids

The OSTAR2002 grids are based on the line-blanketed O-star model atmospheres published in Lanz & Hubeny (2003). Spectra are calculated from these atmospheres using SYNSPEC, and their angle dependence parameterized with the CLARET limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [27500, 55000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [3.0, 4.75]
• metallicity Z/Zo = Z/Z☉ ∈ [0.02, 2]

BSTAR2006 Grids

The BSTAR2006 grids are based on the line-blanketed B-star model atmospheres published in Lanz & Hubeny (2007). Spectra are calculated from these atmospheres using SYNSPEC, and their angle dependence parameterized with the CLARET limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [15000, 30000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [1.75, 4.75]
• metallicity Z/Zo = Z/Z☉ ∈ [0, 2]

C3K Grids

The C3K grids are based on the data described in section 5.4 of Choi et a. (2016), kindly shared by the MIST team. The angle dependence of spectra is parameterized with the CONST limb-darkening law.

Note: currently there are some voids in the C3K grids that can cause interpolation to fail. We are looking into ways to repair these holes, and will release a new set of grids if successful.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [2500, 46000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [-1.0, 5.5]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-2.5, 0.5]
• alpha enhancement [alpha/Fe] = log₁₀[(α/Fe)/(α/Fe)☉] ∈ [-0.2, 0.6]

CAP18 Grids

The CAP18 grids are based on the data published in Allende Prieto et al. (2018) (the letters ‘CAP’ are the initials of the first author). The angle dependence of spectra is parameterized with the CONST limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [3500, 30000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 5.0]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-5.0, 0.5]
• alpha enhancement [alpha/Fe] = log₁₀[(α/Fe)/(α/Fe)☉] ∈ [-1.0, 1.0]
• microturbulent velocity log(xi) = log₁₀(ξ/cm s^-1) ∈ [-0.301, 0.903]

Coelho14 Grids

The Coelho14 grids are based on the data described in Coelho (2014) and available for download from specmodels.iag.usp.br/. The angle dependence of spectra is parameterized with the CONST limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [3000, 22000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [-0.5, 5.5]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-1.0, 0.2]
• alpha enhancement [alpha/Fe] = log₁₀[(α/Fe)/(α/Fe)☉] ∈ [0, 0.4]

Göttingen Grids

The Göttingen grids are based on the data described in Husser et al. (2013) and available for download from phoenix.astro.physik.uni-goettingen.de. The angle dependence of spectra is parameterized with the CONST limb-darkening law.

Alpha-dependent Grids

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [3500, 8000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 6.0]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-3.0, 0.0]
• alpha enhancement [alpha/Fe] = log₁₀[(α/Fe)/(α/Fe)☉] ∈ [-0.2, 1.2]

Solar-alpha Grids

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [2300, 12000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 6.0]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-4.0, 1.0]

SPHINX Grids

The SPHINX grids are based on the data described in Iyer et al. (2023) and available for download from zenodo.org/record/7416042. The angle dependence of spectra is parameterized with the CONST limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [2000, 4000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [4.0, 5.5]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-1.0, 1.0]
• carbon-to-oxygen C/O = N_C/N_O ∈ [0.3, 0.9]

BT-Settl Grids

The BT-Settl grids are based on the data described in Allard et al. (2012) and available for download from the Spanish Virtual Observatory (SVO). The angle dependence of spectra is parameterized with the CONST limb-darkening law.

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [400, 2500]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 5.5]

NewEra Grids

The NewEra grids are based on the data described in Hauschildt et al. (2025) and available for download from www.fdr.uni-hamburg.de/record/17935. The angle dependence of spectra is parameterized with the CONST limb-darkening law.

Alpha-dependent Grids

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [2300, 12000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 6.0]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-2.0, 0.0]
• alpha enhancement [alpha/Fe] = log₁₀[(α/Fe)/(α/Fe)☉] ∈ [-0.2, 1.2]

Solar-alpha Grids

The definitions and ranges of the photospheric parameters are as follows:

• effective temperature Teff = T_eff/K ∈ [2300, 12000]
• surface gravity log(g) = log₁₀(g/cm s^-2) ∈ [0.0, 6.0]
• metallicity [Fe/H] = log₁₀[(Fe/H)/(Fe/H)☉] ∈ [-4.0, 0.5]