J/A+A/611/A68 3D correction in 5 photometric systems (Bonifacio+, 2018)
Using the CIFIST grid of CO5BOLD 3D model atmospheres to study
the effects of stellar granulation on photometric colours.
I. Grids of 3D corrections in the UBVRI, 2MASS, Hipparcos, Gaia, and SDDS
systems.
Bonifacio P., Caffau E., Ludwig H.-G., Steffen M.,Castelli F.,
Gallagher A.J., Kucinskas A., Prakapavicius D., Cayrel R., Freytag B.,
Plez B., Homeier D.
<Astron. Astrophys. 611, A68 (2018)>
=2018A&A...611A..68B 2018A&A...611A..68B
ADC_Keywords: Stars, atmospheres ; Effective temperatures ; Colors ; Models
Keywords: hydrodynamics - radiative transfer - methods: numerical -
techniques: photometric - stars: atmospheres
Abstract:
The atmospheres of cool stars are temporally and spatially
inhomogeneous due to the effects of convection. The influence of this
inhomogeneity, referred to as granulation, on colours has never been
investigated over a large range of effective temperatures and
gravities.
We aim to study, in a quantitative way, the impact of granulation on
colours.
We use the CIFIST (Cosmological Impact of the FIrst Stars) grid of
CO5BOLD (COnservative COde for the COmputation of COmpressible
COnvection in a BOx of L Dimensions, L=2,3) hydrodynamical models to
compute emerging fluxes. These in turn are used to compute theoretical
colours in the UBVRI, 2MASS, Hipparcos, Gaia and SDSS systems. Every
CO5BOLD model has a corresponding one dimensional (1D) plane-parallel
LHD (Lagrangian HydroDynamics) model computed for the same atmospheric
parameters, which we used to define a "3D correction" that can be
applied to colours computed from fluxes computed from any 1D model
atmosphere code. As an example, we illustrate these corrections
applied to colours computed from ATLAS models.
The 3D corrections on colours are generally small, of the order of a
few hundredths of a magnitude, yet they are far from negligible. We
find that ignoring granulation effects can lead to underestimation of
Teff by up to 200K and overestimation of gravity by up to 0.5dex,
when using colours as diagnostics.We have identified a major
shortcoming in how scattering is treated in the current version of the
CIFIST grid, which could lead to offsets of the order 0.01mag,
especially for colours involving blue and UV bands. We have
investigated the Gaia and Hipparcos photometric systems and found that
the (G-Hp),(BP-RP) diagram is immune to the effects of
granulation. In addition, we point to the potential of the RVS
photometry as a metallicity diagnostic.
Our investigation shows that the effects of granulation should not be
neglected if one wants to use colours as diagnostics of the stellar
parameters of F,G,K stars. A limitation is that scattering is treated
as true absorption in our current computations, thus our 3D
corrections are likely an upper limit to the true effect. We are
already computing the next generation of the CIFIST grid, using an
approximate treatment of scattering.
Description:
We have used the CIFIST grid of CO5BOLD models to investigate the
effects of granulation on fluxes and colours of stars of spectral type
F, G, and K.
We publish tables with 3D corrections that can be applied to colours
computed from any 1D model atmosphere. For Teff≥5000K, the
corrections are smooth enough, as a function of atmospheric
parameters, that it is possible to interpolate the corrections
between grid points; thus the coarseness of the CIFIST grid should not
be a major limitation. However at the cool end there are still far too
few models to allow a reliable interpolation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 93 27 Colours and corrections for the Johnson-Cousins
system for metallicity [M/H]=0.0
tablea2.dat 93 26 Colours and corrections for the Johnson-Cousins
system for metallicity [M/H]=-1.0
tablea3.dat 93 27 Colours and corrections for the Johnson-Cousins
system for metallicity [M/H]=-2.0
tablea4.dat 93 27 Colours and corrections for the Johnson-Cousins
system for metallicity [M/H]=-3.0
tablea5.dat 93 27 Colours and corrections for the 2MASS and
Hipparcos-Tycho systems for metallicity [M/H]=0.0
tablea6.dat 93 26 Colours and corrections for the 2MASS and
Hipparcos-Tycho systems for metallicity [M/H]=-1.0
tablea7.dat 93 27 Colours and corrections for the 2MASS and
Hipparcos-Tycho systems for metallicity [M/H]=-2.0
tablea8.dat 93 26 Colours and corrections for the 2MASS and
Hipparcos-Tycho systems for metallicity [M/H]=-3.0
tablea9.dat 93 27 Colours and corrections for the Gaia system
for metallicity [M/H]=0.0
tablea10.dat 93 26 Colours and corrections for the Gaia system
for metallicity [M/H]=-1.0
tablea11.dat 93 27 Colours and corrections for the Gaia system
for metallicity [M/H]=-2.0
tablea12.dat 93 27 Colours and corrections for the Gaia system
for metallicity [M/H]=-3.0
tablea13.dat 93 27 Colours and corrections for SDSS u-g, g-z, g-r
and g-i for metallicity [M/H]=0.0
tablea14.dat 93 26 Colours and corrections for SDSS u-g, g-z, g-r
and g-i for metallicity [M/H]=-1.0
tablea15.dat 93 27 Colours and corrections for SDSS u-g, g-z, g-r
and g-i for metallicity [M/H]=-2.0
tablea16.dat 93 27 Colours and corrections for SDSS u-g, g-z, g-r
and g-i for metallicity [M/H]=-3.0
tablea17.dat 93 27 Colours and corrections for SDSS r-i, i-z, u-i
and u-z for metallicity [M/H]=0.0
tablea18.dat 93 26 Colours and corrections for SDSS r-i, i-z, u-i
and u-z for metallicity [M/H]=-1.0
tablea19.dat 93 27 Colours and corrections for SDSS r-i, i-z, u-i
and u-z for metallicity [M/H]=-2.0
tablea20.dat 93 27 Colours and corrections for SDSS r-i, i-z, u-i
and u-z for metallicity [M/H]=-3.0
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Byte-by-byte Description of file: tablea[1234].dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
6- 9 F4.2 [cm/s2] logg Surface gravity
11- 16 F6.3 mag U-BA ATLAS U-B colour correction
18- 23 F6.3 mag U-BAc ATLAS U-B colour correction with 3D correction
added to the ATLAS colour
25- 30 F6.3 mag dU-B U-B correction difference, U-BA - U-BAc
32- 37 F6.3 mag B-VA ATLAS B-V colour correction
39- 44 F6.3 mag B-VAc ATLAS B-V colour correction with 3D correction
added to the ATLAS colour
46- 51 F6.3 mag dB-V B-V correction difference, B-VA - B-VAc
53- 58 F6.3 mag V-RA ATLAS V-R colour correction
60- 65 F6.3 mag V-RAc ATLAS V-R colour correction with 3D correction
added to the ATLAS colour
67- 72 F6.3 mag dV-R V-R correction difference, V-RA - V-RAc
74- 79 F6.3 mag V-IA ATLAS V-I colour correction
81- 86 F6.3 mag V-IAc ATLAS V-I colour correction with 3D correction
added to the ATLAS colour
88- 93 F6.3 mag dV-I V-I correction difference, V-IA - V-IAc
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Byte-by-byte Description of file: tablea[5678].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
6- 9 F4.2 [cm/s2] logg Surface gravity
11- 16 F6.3 mag J-KA ATLAS J-K colour correction
18- 23 F6.3 mag J-KAc ATLAS J-K colour correction with 3D correction
added to the ATLAS colour
25- 30 F6.3 mag dJ-K J-K correction difference, J-KA - J-KAc
32- 37 F6.3 mag V-KA ATLAS V-K colour correction
39- 44 F6.3 mag V-KAc ATLAS V-K colour correction with 3D correction
added to the ATLAS colour
46- 51 F6.3 mag dV-K B-K correction difference, V-KA - V-KAc
53- 58 F6.3 mag V-HpA ATLAS V-Hp colour correction
60- 65 F6.3 mag V-HpAc ATLAS V-Hp colour correction with 3D correction
added to the ATLAS colour
67- 72 F6.3 mag dV-Hp V-Hp correction colour difference,
V-HpA - V-HpAc
74- 79 F6.3 mag BT-VTA ATLAS BT-VT colour correction
81- 86 F6.3 mag BT-VTAc ATLAS BT-VT colour correction with 3D correction
added to the ATLAS colour
88- 93 F6.3 mag dBT-VT BT-VT correction difference,
BT-VTA - BT-VTAc
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Byte-by-byte Description of file: tablea9.dat tablea1[012].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
6- 9 F4.2 [cm/s2] logg Surface gravity
11- 16 F6.3 mag G-HpA ATLAS G-Hp colour correction
18- 23 F6.3 mag G-HpAc ATLAS G-Hp colour correction with 3D correction
added to the ATLAS colour
25- 30 F6.3 mag dG-Hp G-Hp correction difference,
G-HpA - G-HpAc
32- 37 F6.3 mag BP-RPA ATLAS BT-RP colour correction
39- 44 F6.3 mag BP-RPAc ATLAS BT-RP colour correction with 3D
correction added to the ATLAS colour
46- 51 F6.3 mag dBP-RP BP-RP correction difference,
BP-RPA - BP-RPAc
53- 58 F6.3 mag CaTA ATLAS CaT (=(G-RVS)-(BP-RP)) colour correction
60- 65 F6.3 mag CaTAc ATLAS CaT (=(G-RVS)-(BP-RP)) colour correction
with 3D correction added to the ATLAS colour
67- 72 F6.3 mag dCaT CaT (=(G-RVS)-(BP-RP)) correction difference,
CaTA - CaTAc
74- 79 F6.3 mag BolGA ATLAS bolometric correction
81- 86 F6.3 mag BolGAc ATLAS bolometric correction with 3D correction
added to the ATLAS colour
88- 93 F6.3 mag dBolG Bolometric correction difference,
BolGA - BolGAc
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Byte-by-byte Description of file: tablea1[3456].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
6- 9 F4.2 [cm/s2] logg Surface gravity
11- 16 F6.3 mag u-gA ATLAS u-g colour correction
18- 23 F6.3 mag u-gAc ATLAS u-g colour correction with 3D correction
added to the ATLAS colour
25- 30 F6.3 mag du-g u-g correction difference, u-gA - u-gAc
32- 37 F6.3 mag g-zA ATLAS g-z colour correction
39- 44 F6.3 mag g-zAc ATLAS g-z colour correction with 3D
correction added to the ATLAS colour
46- 51 F6.3 mag dg-z g-z correction difference, g-zA - g-zAc
53- 58 F6.3 mag g-rA ATLAS g-r colour correction
60- 65 F6.3 mag g-rAc ATLAS g-r colour correction
with 3D correction added to the ATLAS colour
67- 72 F6.3 mag dg-r g-r correction difference, g-rA - g-rAc
74- 79 F6.3 mag g-iA ATLAS g-i colour correction
81- 86 F6.3 mag g-iAc ATLAS g-i colour correction with 3D correction
been added to the ATLAS colour
88- 93 F6.3 mag dg-i g-i correction difference, g-iA - g-iAc
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Byte-by-byte Description of file: tablea1[789].dat tablea20.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
6- 9 F4.2 [cm/s2] logg Surface gravity
11- 16 F6.3 mag r-iA ATLAS r-i colour correction
18- 23 F6.3 mag r-iAc ATLAS r-i colour correction with 3D correction
added to the ATLAS colour
25- 30 F6.3 mag dr-i r-i correction colour difference, r-iA - r-iAc
32- 37 F6.3 mag i-zA ATLAS i-z colour correction
39- 44 F6.3 mag i-zAc ATLAS i-z colour correction with 3D correction
added to the ATLAS colour
46- 51 F6.3 mag di-z i-z correction colour difference, i-zA - i-zAc
53- 58 F6.3 mag u-iA ATLAS u-i colour correction
60- 65 F6.3 mag u-iAc ATLAS u-i colour correction with 3D correction
added to the ATLAS colour
67- 72 F6.3 mag du-i u-i correction colour difference, u-iA - u-iAc
74- 79 F6.3 mag u-zA ATLAS u-z colour correction
81- 86 F6.3 mag u-zAc ATLAS u-z colour correction with 3D correction
added to the ATLAS colour
88- 93 F6.3 mag du-z u-z correction difference, u-zA - u-zAc
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Jan-2018