Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours - II. The role of convection across the H-R diagram
<i>Aims.<i/> We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H-R diagram.<i>Methods.<i/> The 3D hydrodynamical CO<sup>5<sup/>BOLD, averaged ⟨3D⟩,...
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| Hauptverfasser: | , , , , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
25 May 2018
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| In: |
Astronomy and astrophysics
Year: 2018, Jahrgang: 613 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201732447 |
| Online-Zugang: | Verlag, Volltext: https://doi.org/10.1051/0004-6361/201732447 Verlag: https://www.aanda.org/articles/aa/abs/2018/05/aa32447-17/aa32447-17.html 
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| Verfasserangaben: | A. Kučinskas, J. Klevas, H.-G. Ludwig, P. Bonifacio, M. Steffen, and E. Caffau |
| Zusammenfassung: | <i>Aims.<i/> We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H-R diagram.<i>Methods.<i/> The 3D hydrodynamical CO<sup>5<sup/>BOLD, averaged ⟨3D⟩, and 1D hydrostatic LHD model atmospheres were used to compute SEDs of stars on the main sequence (MS), main sequence turn-off (TO), subgiant branch (SGB), and red giant branch (RGB), in each case at two different effective temperatures and two metallicities, [M∕H] = 0.0 and − 2.0. Using the obtained SEDs, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins <i>UBVRI<i/> and 2MASS <i>JHK<i/><sub>s<sub/>, and the medium-band Strömgren <i>uvby<i/> photometric systems.<i>Results.<i/> The 3D-1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed ± 0.03 mag. Only in the case of the coolest giants located on the upper RGB are the differences in the <i>U<i/> and <i>u<i/> bands able reach ≈−0.2 mag at [M∕H] = 0.0 and ≈−0.1 mag at [M∕H] = −2.0. Generally, the 3D-1D differences are largest in the blue-UV part of the spectrum and decrease towards longer wavelengths. They are also sensitive to the effective temperature and are significantly smaller in hotter stars. Metallicity also plays a role and leads to slightly larger 3D-1D differences at [M∕H] = 0.0. All these patterns are caused by a complex interplay between the radiation field, opacities, and horizontal temperature fluctuations that occur due to convective motions in stellar atmospheres. Although small, the 3D-1D differences in the magnitudes and colour indices are nevertheless comparable to or larger than typical photometric uncertainties and may therefore cause non-negligible systematic differences in the estimated effective temperatures. |
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| Beschreibung: | Die 5 im Text ist hochgestellt Gesehen am 18.11.2019 |
| Beschreibung: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201732447 |