Extra-solar planet search using the Subaru Telescope

这项研究计划旨在利用斯巴鲁望远镜日冕成像仪Ciao观测100颗年轻恒星，以探测它们的星周结构和行星候选者。Ciao是世界上最早开始运行的大型光学-红外望远镜之一。在过去的三年里，我们拍摄了大约80颗年轻恒星的图像，现在对数据进行了详细的分析。到目前为止，我们取得了以下两个主要成果：(1)AB金牛座周围原行星盘中螺旋结构的探测首次在年轻恒星AB Aurigae周围的原行星盘中发现了显著的螺旋结构。在原始太阳星云中，行星的形成始于尘埃粒子积累成行星体，然后它们碰撞和聚合形成原行星，如果它们变得足够重，足以吸引周围的气体，这些原行星可能会成长为巨大的气体行星。具有类似行星形成过程的原行星盘是bel…更有可能发生的情况应该是中心恒星质量的1%，并且引力稳定。因此，到目前为止，原行星盘被认为没有由引力不稳定引起的螺旋状结构。这种螺旋结构表明，围绕AB御夫座的原行星盘可能很重，以维持螺旋的不稳定性。如此重的圆盘可能会碎裂，并遵循与太阳系中不同的行星形成路径。(2)发现了一颗40Juniter质量伴星。我们在观测到的年轻恒星中发现了20颗伴星，并正在进行后续观测，以判断他们是否是真正的物理伴星。在这个过程中，我们发现了一颗靠近金牛座的恒星是一颗质量为40木星或0.04太阳质量的恒星。由于行星目前被定义为质量小于13木星质量的伴星，我们的发现意味着行星的直接成像现在几乎近在咫尺。较少

This research program aims to observe one hundred young stars in order to detect their circumstellar structures and planet candidates with CIAO, a Subaru Telescope coronagraphic imager which started its operation early among the large optical-infrared telescopes in the world. We have imaged about 80 young stars for the last three years, now analyzing the data in detail. The followings are the two major results that we have achieved so far.(1)Detection of Spiral Structure in the Protoplanetary Disk around AB AurigaeA prominent spiral structure was for the first time discovered in the protoplanetary disk around the young star AB Aurigae. In the primordial solar nebula, planet formation begins with the accumulation of dust particles into planetesimals, followed by their collision and coalescence to form protoplanets, which may grow up to giant gas planets if they become sufficiently heavy to attract ambient gas. Protoplanetary disks within which the similar planet formation process is bel … More ieved to occur should have masses of order 1% of their central stars and be gravitationally stable. Protoplanetary disks are thus so far believed to have no structure such as spirals caused by gravitational instability. The spiral structure suggests that the protoplanetary disk around AB Aurigae might be heavy to maintain spiral instability. Such a heavy disk might fragment and follow a different path of planet formation than that occurred in our solar system.(2)Discovery of a 40 Juniter Mass Companion to DH TauriWe have detected 20 companion candidates among the observed young stars and are making follow up observations to judge whether or not they are real physical companions. During this process we have found that one star located close to DH Tauri is a physical companion with a 40 Jupiter masses or a 0.04 solar masses. Because planets are for the moment defined as companions with masses less than 13 Jupiter masses, our discovery means that direct imaging of planets is almost at hand now. Less