J/MNRAS/444/392 Synthetic Stellar Photometry. I. (Casagrande+, 2014)
Synthetic Stellar Photometry.
I. General considerations and new transformations for broad-band systems.
Casagrande L., VandenBerg D.A.
<Mon. Not. R. Astron. Soc. 444, 392 (2014)>
=2014MNRAS.444..392C 2014MNRAS.444..392C
ADC_Keywords: Models ; Photometry
Keywords: techniques: photometric - stars: atmospheres -
stars: fundamental parameters -
Hertzsprung-Russell and colour-magnitude diagrams -
globular clusters: general
Abstract:
After a pedagogical introduction to the main concepts of synthetic
photometry, colours and bolometric corrections in the Johnson-Cousins,
2MASS, and HST-ACS/WFC3 photometric systems are generated from MARCS
synthetic fluxes for various [Fe/H] and [α/Fe] combinations, and
virtually any value of E(B-V)≲0.7. The successes and failures of
model fluxes in reproducing the observed magnitudes are highlighted.
Overall, extant synthetic fluxes predict quite realistic broad-band
colours and bolometric corrections, especially at optical and longer
wavelengths: further improvements of the predictions for the blue and
ultraviolet spectral regions await the use of hydrodynamic models
where the microturbulent velocity is not treated as a free parameter.
We show how the morphology of the colour-magnitude diagram (CMD)
changes for different values of [Fe/H] and [α/Fe]; in
particular,how suitable colour combinations can easily discriminate
between red giant branch and lower main sequence populations with
different [α/Fe], due to the concomitant loops and swings in the
CMD. We also provide computer programs to produce tables of synthetic
bolometric corrections as well as routines to interpolate in them.
These colour-Teff-metallicity relations may be used to convert
isochrones for different chemical compositions to various bandpasses
assuming observed reddening values, thus bypassing the standard
assumption of a constant colour excess for stars of different spectral
type.We also show how such an assumption can lead to significant
systematic errors. The MARCS transformations presented in this study
promise to provide important constraints on our understanding of the
multiple stellar populations found in globular clusters (e.g., the
colours of lower main sequence stars are predicted to depend strongly
on [α/Fe]) and of those located towards/in the Galactic Bulge.
Description:
The file readme.txt provides a detailed explanation of the content of
BCtables.tar.gz and BCcodes.tar.gz, along with some details concerning
the execution of their various programs. A quick step-by-step set of
instructions (UNIX/Linux-oriented) is contained in the file
instructions.txt.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
readme.txt 80 297 Explanation of the content of
BCtables.tar and BCcodes.tar
instructions.txt 80 123 Quick step-by-step set of instructions
BCcodes.tar 1101 2517 Fortran computer programs
BCtables.tar 2611 8382627 Tables needed for the code
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Acknowledgements:
Luca Casagrande, luca.casagrande(at)anu.edu.au
History:
26-Aug-2014: on-line version of the files
29-Apr-2015: file getbctable.for corrected (from author)
(End) Patricia Vannier [CDS] 25-Jul-2014