By telescopic tracking, we have established that the orbit of the trans-neptunian object (2000 CR$_{105}$) has a perihelion of $\simeq$44 AU, and is thus outside the domain controlled by strong gravitational close encounters with Neptune. Because this object is on a very large, eccentric orbit (with semimajor axis $a\simeq$216 AU and eccentricity $e\simeq$0.8) this object must have been placed on this orbit by a gravitational perturbation which is {\it not} direct gravitational scattering off of any of the giant planets (on their current orbits). The existence of this object may thus have profound cosmogonic implications for our understanding of the formation of the outer Solar System. We discuss some viable scenarios which could have produced it, including long-term diffusive chaos and scattering off of other massive bodies in the outer Solar System. This discovery implies that there must be a large population of trans-neptunian objects in an `extended scattered disk' with perihelia above the previously-discussed 38 AU boundary.
We report spatially resolved 11.8 micron images, obtained at the W. M. Keck 10 m telescope, of the protoplanetary disk around the pre--main-sequence star HK Tau B. The mid-infrared morphology and astrometry of HK Tau B with respect to HK Tau A indicate that the flux observed in the mid-infrared from HK Tau B has been scattered off the upper surface of its nearly edge-on disk. This is the first example of a protoplanetary disk observed in scattered light at mid-infrared wavelengths. Monte Carlo simulations of this disk show that the extent (FWHM =0."5, or 70 AU) of the scattered light nebula in…
Raman Scattered O VI $λ$ 6825 and the Accretion Disk Emission Model in the Symbiotic Stars V1016 Cygni and HM Sagittae
利用Bohyunsan光学阶梯摄谱仪（BOES）获得了天鹅座V1016和人马座HM的高分辨率光谱，并研究了O VI 6825的双峰非对称拉曼散射轮廓.通过采用风吸积盘模型，我们假设OVI发射区由开普勒薄盘描述。拉曼散射发生在巨星附近的中性区域，以缓慢的恒星风的形式出现，其中一部分被来自热白矮星的强烈紫外线辐射电离。使用蒙特卡罗技术，我们计算的线的配置文件，调制的慢球形恒星风从巨大的组件与电离前近似的双曲面。为了说明的不对称性和存在的中央倾角的配置文件，我们添加了一个O VI共振散射区域之间的热白矮星和巨星，这阻碍了轻微的蓝色O VI光子的H I区域的入射。整体良好的拟合观测数据得到从我们的模型，这有助于支持吸积盘发射模型在这些对象。V1016 Cyg的最佳拟合参数是$v_o=30{\rm km s^{-1}}$、$v_\infty=11{\rm km s^{-1}}$和$v_{c}=10{\rm km s^{-1}}$，其中$v_o$、$v_\infty$和$v_{c}$分别是外盘边缘的速度、巨风的终端速度和沿双星轴的共振散射OVI区的速度分量。对于HM Sge，获得类似的拟合参数$v_o=27{\rm km s^{-1}}$、$v_\infty=10{\rm km s^{-1}}$和$v_{c}=9{\rm km s^{-1}}$。我们还调查了一个热点的影响，是众所周知的吸积盘在…
On a Scattered-Disk Origin for the 2003 El61 Collisional Family - an Example of the Importance of Collisions on the Dynamics of Small Bodies
最近在柯伊伯带发现的2003 EL 61碰撞族（Brown等人，2007年）是令人惊讶的，因为这样一个家庭的形成是一个非常不可能的事件在今天的带。假设Brown et al.的估计的祖先的大小，我们发现，柯伊伯带的对象参与这样的碰撞，因为原始时代的概率是小于约0.001。此外，碰撞不可能发生在大质量的原始柯伊伯带中，因为无论发生什么事件，该家族的动力学相干性都不会幸存下来。在这里，我们建议家庭是两个分散的磁盘对象之间的碰撞的结果。我们表明，两个这样的物体之间发生碰撞的概率与布朗等人（2007）所主张的大小相似，并且由此产生的家庭的质心在柯伊伯带的典型轨道上可以高达47%。考虑到这一估计中涉及的很大的不确定性，这一结果与存在一个这样的家庭是一致的。如果这是真的，这个结果的意义远远超出了单个碰撞家族的起源，因为它表明碰撞在塑造我们今天看到的小天体种群的动力学结构方面发挥了重要作用。
We report the first scattered light detection of a dusty debris disk surrounding the F2V star HD 15115 using the Hubble Space Telescope in the optical, and Keck adaptive optics in the near-infrared. The most remarkable property of the HD 15115 disk relative to other debris disks is its extreme length asymmetry. The east side of the disk is detected to ~315 AU radius, whereas the west side of the disk has radius >550 AU. We find a blue optical to near-infrared scattered light color relative to the star that indicates grain scattering properties similar to the AU Mic debris disk. The existence o…
