The Gould Belt (GB) is a system of gas and young, bright stars distributed along a plane that is inclined with respect to the main plane of the Milky Way. Observational evidence suggests that the GB is our closest star formation complex, but its true nature and origin remain rather controversial. In this work we analyze the fractal structure of the stellar component of the GB. In order to do this, we tailor and apply an algorithm that estimates the fractal dimension in a precise and accurate way, avoiding both boundary and small data set problems. We find that early OB stars (of spectral types earlier than B4) in the GB have a fractal dimension very similar to that of the gas clouds in our Galaxy. On the contrary, stars in the GB of later spectral types show a larger fractal dimension, similar to that found for OB stars of both age groups in the local Galactic disk (LGD). This result seems to indicate that while the younger OB stars in the GB preserve the memory of the spatial structure of the cloud where they were born, older stars are distributed following a similar morphology as that found for the LGD stars. The possible causes for these differences are discussed.
Gould Belt Kinematics on the Base of the Open Clusters and Ob-Associations
利用附近年轻（$\log t<7.91$）疏散星团、OB星协和运动恒星群的现代运动数据，重新确定了古尔德带的运动学参数。进行的模拟表明，剩余速度达到最大值等于-4 km s $^{-1}$的旋转（在银河系旋转的方向）和$+4$ km s $^{-1}$的膨胀，当到运动中心的距离约为300秒差距。我们假设古尔德带中心的以下参数：$l_\circ=128^\circ$和$R_\circ=150$ pc。结果表明，古尔德带的整个结构是相对于当地的静止标准的移动速度$10.7\pm0.7$公里s PDMATHAMN的方向上的$l=274\pm4^\circ$，$b=-1\pm3^\circ$。利用旋转速度，我们得到了古尔德带质量的维里估计为$1.5\times 10^6 M_\odot$。
Gamma-ray Emission Properties from Mature Pulsars in the Galaxy and in the Gould Belt
利用一个新的自洽外能隙模型研究了类星体的$γ$射线辐射特性。如果考虑磁倾角的影响以及外能隙的平均性质，那么年龄在百万年以上的恒星也可能存在外能隙。成熟的$γ$射线双星的年龄在30万年到300万年之间，能够向银河系高纬度移动。此外，它们的$γ$射线光度在银道面上明显弱于年轻的$γ$射线恒星，光谱也明显柔和。我们用蒙特卡罗方法模拟银河系和古尔德带中的$γ$射线天体的统计特性。我们发现位于$\mid b \mid < 5^{\circ}$和位于$\mid b \mid > 5^{\circ}$的$γ$射线源具有非常不同的性质。高银纬$γ$射线双星主要是周期较长、通量较弱、光谱较软的成熟双星。如果银河系和古尔德带的脉冲星出生率分别为$\sim 10^{-2}yr^{-1}$和$\sim 2\times 10^{-5}yr^{-1}$，则$\mid b \mid < 5^{\circ}$和$\mid b \mid > 5^{\circ}$分别有42和35个射电宁静$γ$射线源。来自古尔德带的无线电静默$γ$射线谱分别为2和13，分别为$\mid b \mid < 5^{\circ}$和$\mid b \mid > 5^{\circ}$。我们认为，一个很好的比例不明EGRET $γ$-射线源可能是这些无线电安静的$γ$-射线源。此外，位于$\mid b \mid > 5^{\circ}$的$γ…
