@misc{oai:ir.soken.ac.jp:00000356,
 author = {鈴木, 美郁 and スズキ, ミカ and SUZUKI, Mika},
 month = {2016-02-17, 2016-02-17},
 note = {Star formation is one of the most fundamental subjects should be addressed in the modern astrophysics. The study of star formation has a long history and has been successful for 
the case of single stellar collapse. However it is now well established that approximately two-thirds of all solar-type field stars are members of binary or multiple systems (Duquennoy and Mayor 1991). Binary star formation seems to be a natural process. Hence the primary mechanism by which they form should be identified. In order to establish the exact theory of binary star formation observational constraint is necessary. Observations using millimeter- wave Interferometer are one of the effective way to investigate the environments at small scale around protostellar binary systems, which are still embedded in molecular gas and dust. In this thesis we have made aperture synthesis observations of a candidate of protostellar binary system IRAS 16293-2422, which consists of two radio sources A and B at a separation of 840 AU (Wootten 1989) and has two pairs of molecular outflows (Mizuno et al. 1990), and tried to get information leading to an implication for binary formation mechanism.
The aperture synthesis observations for IRAS 16293-2422 were carried out using the Nobeyama Millimeter Array (NMA) with the molecular lines of C32S J = 2 - 1, J = 3 - 2, and C34S J = 2 - 1, and with 98 and 147 GHz continuum emissions. <br />We derived four features of molecular gas:(1) Rotating disk of the molecular gas just centered at source A, whose mass and size are 0.23 M〓 and 3200 AU × 1300 AU, respectively,(2) EW elongation of molecular gas associated with source A whose mass is 0.024 M〓,(3) Compact blue-wing component centered at source A, whose mass is 0.01 M〓, and(4) Molecular gas closely associated with source B, whose mass is 0.05 M〓.<br />From the continuum emission we derived two kind of dust environments: (1) Compact dust disks surrounding each central protostar, whose masses are 0.01 M〓 and 0.03 M〓 , respectively. (2)Extended dust envelopes of 500 AU scale around each of source A and B, whose masses are 0.3 M〓 and 0.5 M〓, respectively.<br />In summary, the 2000 AU scale molecular envelope is more massive around source A than source B, while the 500 AU scale dust envelope has almost the same mass. The compact disk around sources A is less massive than that around source B.<br />These observational evidences imply that the two sources are in the different evolutionary phases. Around source A a molecular envelope still exists to fall onto a center and a central compact disk have not yet grown. Around source B the envelope begins to disappear, while the accretion disk have grown to possess a large mass. It is very probable that source A is just in an active phase of protostar deeply embedded in the dense gas envelope, considering that source A has free-free emission, H〓O masers, and shocked molecular gas (Wbootten 1989; Mundy et al. 1992). Source B might be in elder protostar phase than source A or in young T Tauri phase. An age difference between sources A and B is estimated to be 104 - 106 years.<br />We investigate the kinematics and dynamical instability of the molecular gas disk around source A. The rotation velocity seems to be roughly consistent with or slightly smaller than estimated Keplerian velocity. However it is not clear whether the disk is rotationally supported or not, because of large uncertainties in the rotation velocity and the stellar mass. The disk mass of 0.53 M〓 (the compact dust envelope and the gas disk) is comparable to or higher than the stellar mass of 0.2 - 0.5 M〓. This means that the disk is actually unstable.<br />The configuration of the binary system is estimated using the quantities obtained by our observations. The estimated configuration implies that the plane of the binary orbit and that of the disk around source A is not coplanar. Hence it is possible that the gas disk around source A may precess around the binary axis under the gravitational effect of source B. The disk precession could explain the two outflows originated from source A, which show activities related to the outflows. However, if inner portion of the disk controls the direction of the outflow, it is difficult to explain the multiple outflows by the disk precession., application/pdf, 総研大甲第155号},
 title = {連星系をなす原始星 IRAS 16293-2422の観測的研究},
 year = {}
}