Title: Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. II. The role of convection accross the H-R diagram Show Chinese title

Title: 利用CO5BOLD三维模型大气的CIFIST网格研究恒星粒度对光电颜色的影响。 二。 对流在整个赫罗图中的作用

Abstract: We studied the influence of convection on the spectral energy distributions, photometric magnitudes, and colour indices of different types of stars across the H-R diagram. The 3D hydrodynamical CO5BOLD, averaged <3D>, and 1D hydrostatic LHD model atmospheres were used to compute spectral energy distributions 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 spectral energy distributions, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins $UBVRI$ and 2MASS $JHK_{\rm s}$, and the medium-band Str\"{o}mgren $uvby$ photometric systems. The 3D-1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed $\pm0.03$ mag. Only in the case of the coolest giants located on the upper RGB are the differences in the $U$ and $u$ bands able reach $\approx-0.2$ mag at [M/H]=0.0 and $\approx-0.1$ 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. Show Chinese abstract

Abstract: 我们研究了对流对不同类型的恒星沿赫罗图的光谱能量分布、光度大小和颜色指数的影响。 使用三维流体力学CO5BOLD模型、三维平均化<3D>模型以及一维静力平衡LHD模型大气，计算了主序（MS）、主序转折点（TO）、次矮星支（SGB）和红巨星支（RGB）上恒星的光谱能量分布，每种情况在两种不同的有效温度和两种金属丰度[M/H]=0.0和-2.0下进行了计算。 利用获得的光谱能量分布，我们在宽波段Johnson-Cousins $UBVRI$和2MASS $JHK_{\rm s}$光学系统以及中等波段Strömgren $uvby$光学系统中计算了光度大小和颜色指数。 在两种光学系统中，光度大小和颜色指数的三维-一维差异较小，通常不超过$\pm0.03$个星等。 仅在最冷的巨星位于上部红群聚（upper RGB）的情况下，$U$和$u$波段之间的差异才能达到 [M/H]=0.0 时的$\approx-0.2$魔力值，以及 [M/H]=-2.0 时的$\approx-0.1$魔力值。 一般来说，三维（3D）与一维（1D）之间的差异在光谱的蓝-紫外部分最大，并随着波长增加而减小。 它们还对有效温度敏感，在较热的恒星中显著减小。 金属丰度也起到一定作用，在 [M/H]=0.0 时导致略微更大的 3D-1D 差异。 所有这些模式都是由辐射场、吸收系数以及由于恒星大气对流运动引起的水平温度波动之间复杂的相互作用所造成的。 尽管很小，但大小和颜色指数上的 3D-1D 差异仍然相当于或大于典型的测光不确定性，因此可能导致估算的有效温度存在不可忽略的系统性差异。