论文标题
S0星系外环中的星形形成。 iii。 UGC 5936- S0带有目前积累的卫星物质
Star formation in outer rings of S0 galaxies. III. UGC 5936 -- an S0 with currently accreted satellite matter
论文作者
论文摘要
尽管S0星系通常被认为是“红色和死亡”，但它们通常在环结构中表现出恒星形成。我们试图阐明这种现象的性质及其与螺旋星系中恒星形成的差异。这里研究了带有大环5936的发光S0星系。通过沿UGC 5936的主要轴施加长时间光谱，我们已经测量了气体和星形运动学，为星系主体的舔指数以及环中的强发射线磁通量。在使用线比诊断图中检查环中的气体激发并确保其主要由年轻恒星电离后，我们通过使用流行的强线方法确定了气体氧的丰度。另外，我们已经证明了东南矮人卫星与UGC 5936的空间接近，并测量了其气体金属性。环的离子气体被年轻的恒星激发，并具有太阳金属性。环中的恒星形成相当长，其强度对应于UGC 5936的当前HI含量（与Kennicutt-Schmidt关系）。 HI分布的整个形态意味着当前的冷气体从卫星上积聚到UGC 5936的外盘上；由于卫星位置和宿主星系恒星盘平面的旋转，积聚是光滑的，层流为恒星形成点火提供了有利的条件。
Though S0 galaxies are usually thought to be `red and dead', they demonstrate often star formation organized in ring structures. We try to clarify the nature of this phenomenon and its difference from star formation in spiral galaxies. The luminous S0 galaxy with a large ring, UGC 5936, is studied here. By applying long-slit spectroscopy along the major axis of UGC 5936, we have measured gas and star kinematics, Lick indices for the main body of the galaxy, and strong emission-line flux ratios in the ring. After inspecting the gas excitation in the ring using line ratios diagnostic diagrams and having ensured that it is ionized mostly by young stars, we have determined the gas oxygen abundance by using popular strong-line methods. Also we have proved the spatial proximity of the south-eastern dwarf satellite to UGC 5936 and have measured its gas metallicity. The ionized gas of the ring is excited by young stars and has solar metallicity. Star formation in the ring is rather prolonged, and its intensity corresponds to the current HI content of UGC 5936 (to the Kennicutt-Schmidt relation). The whole morphology of the HI distribution implies current accretion of the cold gas from the satellite onto the outer disc of UGC 5936; due to the satellite location and rotation in the plane of the stellar disc of the host galaxy, the accretion is smooth and laminar providing the favorable condition for star formation ignition.
