OBSERVATIONAL RESEARCH OF ACCRETION IN PROTOPLANETARY DISKS

在这项研究中，我们通过天文观测研究了星星形成和原行星盘形成的动力学坍缩，在1996财政年度的研究中，在两颗新的原恒星周围发现了动力学坍缩的直接证据。这两个天体都在1000个天文单位（Au）的包络半径下旋转和下沉，这表明在中心天体周围存在着100个Au尺度的原行星盘，这一点实际上已经从其他观测中得到了证实。因此，我们的结果提供了有力的证据，原行星盘，这将是行星系统形成的网站，是通过动力吸积在原恒星信封。我们研究了统计特征的原恒星信封在1997财政年度的基础上，新的观测，发现，虽然在半径大于0.03秒差距（pc）时包层中气体的比角动量与半径的1.6次方成比例，它与半径无关，在半径小于0.03pc时，约为10^<-3>km s^<-1>pc。这可能意味着原恒星包层中的动力学坍缩发生在半径为0.03 pc的范围内，因此，气体保持其特定的角动量，形成半径为100 Au的原行星盘。这一新结果自然地解释了太阳系100 Au尺度以及原行星盘的尺度。

In this research we investigated, through astronomical observations, dynamical collapse in star formation and formation of protoplanetary disks.Direct evidence of dynamical infall was found around two new protostars during the research in the fiscal year 1996. Both objects showed rotation as well as infall at the envelope radius of about 1000AU (=Astronomical Unit), suggesting the presence of 100 AU scale protoplanetary disks around the central objects, which were actually confirmed from other observations. Our results hence gave firm evidence of protoplanetary disks, which would be the site of planetary system formation, to be formed through dynamical accretion in protostellar envelopes.We then studied statistical characteristics of protostellar envelopes in the fiscal year 1997 based upon new observations, finding that, while the specific angular momentum of gas in envelopes is proportional to the 1.6-th power of the radius at radii larger than 0.03 parsec (pc), it is independent of radius and is constant at about 10^<-3> km s^<-1>pc at radii less than 0.03pc. This may mean that dynamical collapse in protostellar envelopes occurs inside radii of 0.03 pc and that, as a result, the gas keeps its specific angular momentum to form protoplanetary disks with their radii comparable to 100 AU.This new result naturally explains the 100 AU size scale of the solar system as well as that of protoplanetary disks.