一个密集的尘埃盘围绕着再次出现的樱井的物体
A dense disk of dust around the born-again Sakurai's object
摘要：
1996年，樱井的天体（V4334 Sgr）在一个暗淡的行星状星云（PN）的中心突然变亮。这一非常罕见的事件被解释为热白矮星的重新点燃，导致快速演化回到冷巨星阶段。从1998年开始，大量的尘埃不断形成，筛选出仍然嵌入在这个不断扩大的高光学深度包层中的恒星。这里报道的新观测结果用于研究星周尘埃的形态，以研究樱井的物体被厚厚的球形尘埃包围的假设。我们已经获得了前所未有的，高角分辨率光谱干涉观测，采取了中红外干涉仪ESTA/VLTI，解决了樱井的对象的灰尘信封。我们报告发现了一个出乎意料的紧凑（30 x 40毫弧秒，105 x 140 AU，假设距离为3.5 kpc），高度倾斜的尘埃盘。我们使用蒙特卡罗辐射传输模拟的分层磁盘约束其几何和物理参数，虽然这样的模型只是一个粗略的近似快速演变的尘埃结构。即使拟合不完全令人满意，也可以推断出一些有用且鲁棒的约束。盘的倾角估计为75+/-3度，大尺度高度为47+/-7 AU。尘埃盘的质量估计为6 × 10^{-5}太阳质量。椎间盘的长轴（132+/-3度）与旧PN中观察到的不对称性对齐，作为本研究的一部分，对旧PN进行了重新研究。这意味着，当旧PN形成时，负责塑造樱井物体周围尘埃封套的机制已经在工作。
英文摘要：
In 1996, Sakurai's object (V4334 Sgr) suddenly brightened in the centre of a faint Planetary Nebula (PN). This very rare event was interpreted as the reignition of a hot white dwarf that caused a rapid evolution back to the cool giant phase. From 1998 on, a copious amount of dust has formed continuously, screening out the star which has remained embedded in this expanding high optical depth envelope. The new observations, reported here, are used to study the morphology of the circumstellar dust in order to investigate the hypothesis that Sakurai's Object is surrounded by a thick spherical envelope of dust. We have obtained unprecedented, high-angular resolution spectro-interferometric observations, taken with the mid-IR interferometer MIDI/VLTI, which resolve the dust envelope of Sakurai's object. We report the discovery of a unexpectedly compact (30 x 40 milliarcsec, 105 x 140 AU assuming a distance of 3.5 kpc), highly inclined, dust disk. We used Monte Carlo radiative-transfer simulations of a stratified disk to constrain its geometric and physical parameters, although such a model is only a rough approximation of the rapidly evolving dust structure. Even though the fits are not fully satisfactory, some useful and robust constraints can be inferred. The disk inclination is estimated to be 75+/-3 degree with a large scale height of 47+/-7 AU. The dust mass of the disk is estimated to be 6 10^{-5} solar mass. The major axis of the disk (132+/-3 degree) is aligned with an asymmetry seen in the old PN that was re-investigated as part of this study. This implies that the mechanism responsible for shaping the dust envelope surrounding Sakurai's object was already at work when the old PN formed.
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