BolometricCorrections.jl

A bolometric correction (BC) is the offset between a star's absolute bolometric magnitude and its absolute magnitude in a specific bandpass or filter (e.g., V band). In order to place theoretical stellar models into observational filter spaces, bolometric corrections must be applied to the bolometric magnitudes of the stellar models. Here we provide access to and interpolation of pre-computed grids of bolometric corrections. See our documentation linked in the badges above for additional information. Currently supported bolometric correction grids are

• MIST — two versions are supported:
  • v1.2: metallicity ([Fe/H]) and extinction (Av) as free parameters
  • v2.5: adds [α/Fe] as a free parameter and assumes different solar abundances than v1.2
• YBC, which interpolates between several different BC libaries -- supported sub-libraries are
  • PHOENIX
  • ATLAS9
  • Koester & Tremblay white dwarf library
  • WM-basic library of O and B stars

This package integrates with StellarTracks.jl to interpolate isochrones from stellar tracks and apply bolometric corrections to place the isochrones in the observational magnitude space.

Installation

This package is registered to Julia's General registry and can be installed via Pkg from the Julia REPL by executing

import Pkg;
Pkg.add("BolometricCorrections");

Example Usage

MIST v1.2

The HST ACS WFC bolometric corrections from the MIST v1.2 grid can be loaded with

using BolometricCorrections
grid = MISTv1BCGrid("hst_acs_wfc")

If you haven't yet acquired these data, you will be prompted to allow the data to be downloaded and installed.

The MIST v1.2 grid covers a wide range of metallicity and reddening (Av) values. We can interpolate the grid at specific values of [Fe/H] and reddening (Av), obtaining a MISTv1BCTable with

feh, Av = -1.01, 0.125
table = grid(feh, Av)

This table can now be interpolated at any supported value of effective temperature (Teff, in Kelvin) and surface gravity (logg) as

Teff, logg = 2755, 0.01
table(Teff, logg)

which will return a vector containing the bolometric corrections in all the filters defined in the HST ACS WFC system. These filters can be listed with

filternames(grid)

(:ACS_WFC_F435W, :ACS_WFC_F475W, :ACS_WFC_F502N, :ACS_WFC_F550M, :ACS_WFC_F555W, :ACS_WFC_F606W, :ACS_WFC_F625W, :ACS_WFC_F658N, :ACS_WFC_F660N, :ACS_WFC_F775W, :ACS_WFC_F814W, :ACS_WFC_F850LP, :ACS_WFC_F892N)

To enable convenient calculation of BCs over many Teff, logg entries, you can call table(Teff, logg) with array arguments,

table([2755, 2756], [0.01, 0.02])

which return the BCs stacked into a matrix. You can also get the results returned as a TypedTables.Table with

using TypedTables: Table
bcs = table(Table, [2755, 2756], [0.01, 0.02])

Table with 13 columns and 2 rows:
     ACS_WFC_F435W  ACS_WFC_F475W  ACS_WFC_F502N  ACS_WFC_F550M  ACS_WFC_F555W  ACS_WFC_F606W  ACS_WFC_F625W  ⋯
   ┌───────────────────────────────────────────────────────────────────────────────────────────────────────────
 1 │ -6.69738       -5.82358       -6.59423       -4.8335        -5.13368       -4.21906       -3.92446       ⋯
 2 │ -6.67498       -5.80464       -6.57631       -4.81631       -5.11675       -4.20532       -3.91145       ⋯

so that the results can be more conveniently accessed with the following syntax

bcs.ACS_WFC_F435W # Retrieve BCs in F435W filter

MIST v2.5

The MIST v2.5 grid adds [α/Fe] as a free parameter. Load and use it in the same way, passing the additional afe argument when constructing the table:

using BolometricCorrections
grid = MISTv2BCGrid("hst_acs_wfc")
feh, afe, Av = -1.01, 0.2, 0.125
table = grid(feh, afe, Av)
table(2755, 0.01)

YBC

The YBC grid blends several atmosphere libraries (PHOENIX for cool stars, ATLAS9 for hot stars, Koester/Tremblay for white dwarfs, and WM-basic for O/B stars) into a single interface. The top-level YBCGrid type handles the transitions between libraries automatically:

using BolometricCorrections
grid = YBCGrid("jwst_nircam_wide")

A BC table with fixed metallicity ([M/H]) and reddening (Av) is obtained by calling the grid:

mh, Av = -1.0, 0.0
table = grid(mh, Av)

The table is then callable with (Teff [K], logg [cgs]) exactly as for the MIST grids:

table(5778, 4.44)           # single point
table([4000, 5778], [2.0, 4.44])  # array broadcast → matrix

The individual sub-library grids (PHOENIXYBCGrid, ATLAS9YBCGrid, etc.) can also be used directly if you only need one atmosphere library. See the documentation for details.