Koester & Tremblay White Dwarfs

This submodule (BolometricCorrections.YBC.KoesterWD) enables interaction with the "YBC" bolometric correction (BC) grid calculated from the white dwarf libraries of Koester (2010) and Tremblay and Bergeron (2009). These works used Gaia DR2 parallaxes to obtain absolute photometry for white dwarfs, enabling better calibration of the appropriate BCs. The model atmospheres are hosted by SVO here. They provide the following description of the models:

Info

These models are for white dwarfs of spectral type DA with pure hydrogen atmospheres. They use LTE (local thermodynamic equilibrium), hydrostatic equilibrium and plane-parallel, one-dimensional structure. Basic methods and data are described in Koester (2010, Mem.S.A.It. Vol. 81, 921). Since then many improvements were implemented, most notably the hydrogen Stark profiles by Tremblay & Bergeron (2009, ApJ 696,1755), and Tremblay (2015, priv. comm).

Details on the BC calculations are given in section 3.6 of Chen et al. (2019). As these models should only be used for white dwarfs, we do not export the grid and table types from this submodule, indicating that they are treated as internal. This library of models is only used for white dwarf stars in the integrated YBC grid implementation, with details on that page. These models do not vary with metallicity as they consider only pure hydrogen atmospheres. The full range of dependent variables covered by this grid is given in the table below.

	min	max
Teff	5,011 K	79,432 K
logg	6.5	9.5
Av	0.0 mag	20.0 mag
Rv	3.1	3.1

Types

BolometricCorrections.YBC.KoesterWD.KoesterWDYBCGrid — Type

KoesterWDYBCGrid(grid::AbstractString) <: AbstractBCGrid

Load and return the YBC Koester white dwarf bolometric corrections for the given photometric system grid, which must be a valid entry in BolometricCorrections.YBC.systems. This type is used to create instances of KoesterWDYBCTable that have fixed dependent grid variables (Av). This can be done either by calling an instance of KoesterWDYBCGrid with an Av argument or by using the appropriate constructor for KoesterWDYBCTable. Note that there is no variation with metallicity for this grid as it is specialized for white dwarfs only.

julia> using BolometricCorrections.YBC.KoesterWD: KoesterWDYBCGrid

julia> grid = KoesterWDYBCGrid("acs_wfc")
YBC Koester white dwarf bolometric correction grid for photometric system YBC/acs_wfc.

julia> grid(0.11) # Can be called to construct table with interpolated Av
YBC Koester white dwarf bolometric correction table with for system YBC/acs_wfc with V-band extinction 0.11

As most subtypes of AbstractBCGrid accept two arguments grid(MH, Av), we allow this call signature as well, but the MH argument is effectively ignored.

julia> grid(-1, 0.11)
YBC Koester white dwarf bolometric correction table with for system YBC/acs_wfc with V-band extinction 0.11

source

BolometricCorrections.YBC.KoesterWD.KoesterWDYBCTable — Type

KoesterWDYBCTable(grid::AbstractString, Av::Real) <: AbstractBCTable

Interpolates the YBC bolometric corrections based on the white dwarf libraries of Koester (2010) and Tremblay and Bergeron (2009) which used Gaia DR2 parallaxes to obtain absolute photometry to a fixed V-band extinction (Av), leaving only Teff and logg as dependent variables (only one value of Rv is provided). Returns an instance that is callable with arguments (Teff [K], logg [cgs]) to interpolate the bolometric corrections as a function of temperature and surface gravity.

julia> using BolometricCorrections.YBC.KoesterWD: KoesterWDYBCGrid, KoesterWDYBCTable

julia> grid = KoesterWDYBCGrid("acs_wfc")
YBC Koester white dwarf bolometric correction grid for photometric system YBC/acs_wfc.

julia> table = KoesterWDYBCTable(grid, 0.011) # Interpolate table from full grid
YBC Koester white dwarf bolometric correction table with for system YBC/acs_wfc with V-band extinction 0.011

julia> length(table(10_250, 7.65)) == 12 # Returns BC in each filter
true

julia> size(table([10_250, 10_450], [7.65, 7.75])) # `table(array, array)` is also supported
(12, 2)

julia> using TypedTables: Table # `table(Table, array, array)` will return result as a Table

julia> table(Table, [10_250, 10_450], [7.65, 7.75]) isa Table
true

julia> KoesterWDYBCTable("acs_wfc", 0.5) isa KoesterWDYBCTable # Can construct without a KoesterWDYBCGrid
true

source

Chemistry

No chemistry information is provided as these models assume pure hydrogen atmospheres. As such, calling chemistry with one of the above types will return missing.

using BolometricCorrections.YBC.KoesterWD: KoesterWDYBCGrid, chemistry
chemistry(KoesterWDYBCGrid("acs_wfc"))

missing

KoesterWD References

This page cites the following references:

Chen, Y.; Girardi, L.; Fu, X.; Bressan, A.; Aringer, B.; Dal Tio, P.; Pastorelli, G.; Marigo, P.; Costa, G. and Zhang, X. (2019). YBC: a stellar bolometric corrections database with variable extinction coefficients. Application to PARSEC isochrones. A & A 632, A105, arXiv:1910.09037 [astro-ph.SR].
Koester, D. (2010). White dwarf spectra and atmosphere models. Memorie della Societa Astronomica Italiana 81, 921–931.
Tremblay, P. E. and Bergeron, P. (2009). Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Nonideal Effects. ApJ 696, 1755–1770, arXiv:0902.4182 [astro-ph.SR].