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arXiv 1202.2257astro-ph.EP
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改进的Edge-Kuiper碎片盘模型

An improved model of the Edgeworth-Kuiper debris disk

Christian Vitense, Alexander V. Krivov, Hiroshi Kobayashi, Torsten Löhne

摘要:

(节略)我们通过建模获得预期的EKB尘埃盘属性。我们把已知的穿海王星天体(TNOs)作为母体,用我们的碰撞代码产生尘埃。由此产生的尘埃分布进行修改,以考虑到引力散射和共振捕获的行星上迁移的尘埃颗粒的影响,以及升华的效果。一个困难是,尘埃的数量和分布在很大程度上取决于亚公里大小的物体。这些是直接不可观察的,它们的属性不能通过碰撞建模来访问,因为大于10的物体…在现今的EKB中,60米的区域不处于碰撞平衡状态。为了施加额外的限制,我们在20 AU内对新视野号航天器进行了现场测量。我们表明,TNO人口有一个中断的大小分布在s<70公里。然而,即使这样,我们仍然有几个模型,都正确地再现了一个几乎恒定的尘埃撞击率在该地区的巨行星轨道,并没有违反的限制,从非检测的EKB尘埃热辐射的COBE航天器。模型化的EKB尘埃盘,符合观测约束,可以是运输为主或运输为主和碰撞为主的制度之间的中间。这种盘的面内光学厚度为τ(r> 10 AU)~10^-6,其分光度为f_d~10^-7。行星和升华被发现对尘埃撞击通量和尘埃热发射的影响很小。EKB模拟物的光谱能量分布,从10 pc的距离可以看出,在40…50 \mum在F~0.5mJy,这是不到1%的光球通量在这些波长。因此,精确的EKB类似物不能用当今的仪器如Herschel/PACS检测。

英文摘要:

(Abridged) We access the expected EKB dust disk properties by modeling. We treat the debiased population of the known transneptunian objects (TNOs) as parent bodies and generate the dust with our collisional code. The resulting dust distributions are modified to take into account the influence of gravitational scattering and resonance trapping by planets on migrating dust grains as well as the effect of sublimation. A difficulty is that the amount and distribution of dust are largely determined by sub-kilometer-sized bodies. These are directly unobservable, and their properties cannot be accessed by collisional modeling, because objects larger than 10...60m in the present-day EKB are not in a collisional equilibrium. To place additional constraints, we use in-situ measurements of the New Horizons spacecraft within 20AU. We show that the TNO population has to have a break in the size distribution at s<70km. However, even this still leaves us with several models that all correctly reproduce a nearly constant dust impact rates in the region of giant planet orbits and do not violate the constraints from the non-detection of the EKB dust thermal emission by the COBE spacecraft. The modeled EKB dust disks, which conform to the observational constraints, can either be transport-dominated or intermediate between the transport-dominated and collision-dominated regime. The in-plane optical depth of such disks is tau(r>10AU)~10^-6 and their fractional luminosity is f_d~10^-7. Planets and sublimation are found to have little effect on dust impact fluxes and dust thermal emission. The spectral energy distribution of an EKB analog, as would be seen from 10pc distance, peaks at wavelengths of 40...50\mum at F~0.5mJy, which is less than 1% of the photospheric flux at those wavelengths. Therefore, exact EKB analogs cannot be detected with present-day instruments such as Herschel/PACS.

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