A Large Expanding Molecular Arc in the Sagittarius B1 Complex

作者:Tanaka Kunihiko*; Oka Tomoharu; Nagai Makoto; Kamegai Kazuhisa
来源:Publications of the Astronomical Society of Japan, 2009, 61(3): 461-469.
DOI:10.1093/pasj/61.3.461

摘要

Results of molecular line observations toward the Sagittarius B I complex are reported. Maps of the HCN, HCO( ) and SiO J = 1-0 emissions were taken with the NRO 45-m telescope. With these data, combined with the ASTE CO J = 3-2 survey data, we have investigated the spatial structure, kinematics and physical conditions of two peculiar molecular features: CO0.55 0.07 and SiO0.56-0.01. The CO arc, CO0.55 0.07, shows clear expanding motion with sizes of 8.5 x 6.8 pc(2) and an expansion velocity of 40 km s(-1). The SiO shell, SiO0.56-0.01, has a size of 3.0 x 3.4 pc(2), and surrounds an X-ray Fe line source, G0.570-0.018. The mass and the kinetic energy of CO0.55 0.07 are estimated to be 10(5.5) M(circle dot) and 10(51.5) erg, respectively. The kinetic energy of SiO0.56-0.01 is similar to 10(50.4) erg. An LVG analysis shows that the typical density and kinetic temperature are 10(3.8) cm(-3) and 28 K, respectively. High-density clumps with a density of 10(4.0-4.5) cm(-3) associated with CO0.55 0.07 and SiO0.56-0.01 have been found, supporting the idea that they consist of swept-up material. The huge kinetic energy of CO0.55 0.07 is considered to be injected by a series of supernova explosions that took place within similar to 2 x 10(5) yr, which would Suggest that it is a 'bubble' created by a massive stellar cluster, whose mass is estimated to be 10(3.5-4.5) M(circle dot). The origin of SiO0.56-0.01 is rather unclear, but we suggest that it could be related to the X-ray source G0.570-0.018.

  • 出版日期2009