A study of protostars with spectral modeling based on the two-dimensional radiative transfer calculations 2次元輻射輸送計算に基づくスペクトルのモデル計算による原始星の研究

博士論文

application/pdf

We constructed two-dimensional radiative equilibrium protostar model to infer the structure of the Class I objects, which are considered as protostellar candidate. In the present model, we assumed that the protostar consists of three components; a central star, a circumstellar disk, and an envelope. We computed the temperature distribution of the circumstellar material under the condition of the radiative equilibrium. We simulated Spectral Energy Distribution (SED) of Class I object. We first showed that the detailed treatment of radiation transfer is essential to the protostar. We next revealed the relation between the emergent SEDs and the physical structure of the protostar. Based on these results, we established the standard procedure to infer the physical property of the protostar from the emergent SED. Furthermore, we proposed two new indicators,(νLν)max, which is the peak flux of the SED, and fL, which is the ratio of emergent luminosity LSED to the peak flux. The former is useful to estimate the luminosity of the central star, and the latter is effective as an indicator of inclination angle of the system. Finally, we applied the procedure to two protostellar candidates, IRAS 04365+2535(TMC1A), belonging to Class I, and VLA1623, a prototype of Class 0. We showed that these objects surely belong to the observed Classes. We also discussed the evolutionary state of these objects based on the spectral modeling of their SEDs. As a result, TMC1A is in the intermediate phase of the Class I stage of the final mass ~0.3M　, while VLA1623 is in the earlier phase of the Class 0 stage of the final stellar mass ~0.5M .

2002

Includes bibliographical references