We compare the spatial stellar color variations with our three-dimensional analytical model of the spatial dust distribution to refine the properties of the dust layer in Galactic solar neighborhoods. We use a complete sample of 93 992 clump giants with a small admixture of branch giants from the Gaia DR2 catalogue in a spatial cylinder with a radius of 700 pc around the Sun extending to |Z| = 1800 pc along the Galactic Z axis. Accurate parallaxes and photometry of these stars in the Gaia DR2 G_RP and WISE W3 bands have allowed the spatial G_RP - W₃ color variations to be used to calculate the model parameters and two characteristics of the sample, the mode of the dereddened color (G_RP - W3)₀ of the giant clump and the linear change of this mode with coordinate |Z|. As a result, an improved version of the three-dimensional model first proposed by Gontcharov (2009b) has been obtained. As in the previous version, the model suggests two dust layers, along the Galactic equator and in the Gould Belt, that intersect near the Sun at an angle of 18° ± 2°. In contrast to the previous version of the model with a midplane of the Gould Belt dust layer in the form of a circle with the center at the Sun, in the new version this midplane is an ellipse decentered relative to the Sun. A scale height of 170 ± 40 pc has been found for both dust layers. A rather large reddening E(G_RP - W3) = 0.16 ± 0.02 through half of the Galactic dust layer above or below the Sun has been found for giants far from the Galactic plane (|Z| > 600 pc). This can be explained by a possible difference between the extinction law far from the Galactic plane and the commonly adopted law by Cardelli et al. (1989) with R_V = 3.1. The modes of the absolute magnitude M_W3 = -1.70 ± 0.02 and the dereddened color (G_RP - W3)₀ = (1.43 ± 0.01) - (0.020 ± 0.007)|Z|, where Z is expressed in kpc, have been calculated for the giant clump near the Sun. These estimates are consistent with the estimates from the theoretical PARSEC and MIST isochrones for a sample dominated by giants with an age of 2 Gyr and metallicity [Fe/H] = -0.1 in agreement with the TRILEGAL stellar population model. The dispersions of the quantities under consideration have allowed the natural small-scale density fluctuations of the dust medium relative to the mean reddening calculated from the model to be characterized. These fluctuations make a major contribution to the uncertainty in the reddening. Because of them, the reddening of a specific star can differ from the model reddening by a random value that decreases from 80 to <20% of the model reddening when passing from low latitudes far from the Sun to the remaining space.

中文翻译：

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太阳700 pc内银河粉尘层的性质

我们将空间恒星的颜色变化与空间尘埃分布的三维分析模型进行比较，以完善银河系太阳附近尘埃层的特性。我们使用93个992丛集巨人的完整样本，以及来自Gaia DR2目录中的分支巨人的少量混合物，在一个空间圆柱体中围绕太阳旋转700半径，延伸至| Z | 沿银河Z轴= 1800 pc 。Gaia DR2 G _RP和WISE W 3波段中这些恒星的精确视差和光度法已允许空间G _RP - W ₃颜色变化，用于计算模型参数和样品的两个特征，即巨型团块的褪色颜色模式（G _RP - W 3）₀和该模式随坐标|的线性变化。ž|。结果，获得了Gontcharov（2009b）首先提出的三维模型的改进版本。与以前的版本一样，该模型建议沿着银河赤道和古尔德带的两个尘埃层在太阳附近以18°±2°的角度相交。与以前版本的模型不同，该模型的Gould Belt尘埃层的中平面为圆形，且中心位于太阳，在新版本中，该中平面是相对于太阳偏心的椭圆形。两个尘埃层的刻度高度均为170±40 pc。对于远离银河平面的巨星，已经发现了相当大的变红E（G _RP - W 3）= 0.16±0.02，穿过太阳上方或下方的银河尘埃层的一半。Z | > 600个）。可以通过远离银河平面的消光定律和Cardelli等人普遍采用的定律之间的可能差异来解释。（1989），R _V = 3.1。绝对大小M _{W 3} = -1.70±0.02和褪色的颜色（G _RP - W 3）₀ =（1.43±0.01）-（0.020±0.007）| Z |，其中Z以千次曝光出价（kpc）表示，已针对太阳附近的巨型丛计算得出。这些估计与理论上的PARSEC和MIST等时线的估计一致，该样本由年龄为2 Gyr且金属度[Fe / H] = -0.1的巨人为主，与TRILEGAL恒星种群模型一致。所考虑的量的离散度已使粉尘介质的自然小规模密度波动相对于从模型计算出的平均变红现象得以表征。这些波动是导致变红的不确定性的主要因素。因此，特定恒星的变红可能与模型变红的区别是随机值，当从低纬度远离太阳到达剩余空间时，该值会从模型变红的80％降至<20％。