The “Total” Mass of DDO 154
The “Total” Mass of DDO 154
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DDO 154 的“总”质量
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
C. Purton
中科院分区：
文献类型：
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作者：
C. Carignan;C. Purton
结合多明尼安射电天体物理天文台（DRAO）干涉仪阵列的观测数据和以前的甚大阵列（VLA）观测数据，可以恢复DDO 154的所有单碟通量，其中约有1 / 3在VLA数据中丢失。缺失的通量被发现在这个矮不规则星系外部的一个延伸的低表面亮度成分中。在新的组合数据中，在~1.0 × 1019 cm-2的能级上，可以追踪到~6个光学半径（RHo）或21个光学标度长度（α-1）。即使在这个水平上，也没有在大多数其他星系中看到的突然截断的迹象，尤其是在后退的一边。得到的总H I质量为2.5 × 108 M☉，也就是(MH I/LB)≃8，使得DDO 154成为已知的气体最丰富的星系之一。恢复的H I通量使旋转曲线的半径扩大了33%以上，结果表明，DDO 154的旋转曲线是迄今为止推导出的相对于星系光学尺寸最广泛的旋转曲线之一。新的组合数据证实，旋转曲线在外部部分呈下降趋势。详细的质量模型显示，我们可能已经到达了这个星系质量分布的边缘，这将使我们第一次能够估计一个星系的总质量和总范围。对于DDO 154，这给出了估计的总质量Mtot≃3.0 × 109 M☉和Rtot≤8 kpc的径向范围的上限。
Combining data from the Dominion Radio Astrophysical Observatory (DRAO) interferometer array with previous Very Large Array (VLA) observations, it was possible to recover all the single-dish flux of DDO 154, of which ~⅓ was missing from the VLA data. The missing flux was found to be in an extended low surface brightness component in the outer parts of this dwarf irregular galaxy. In the new combined data, the H I disk can be traced out to ~6 optical radii (RHo) or 21 optical scale lengths (α-1) at a level of ~1.0 × 1019 cm-2. Even at that level, there is no sign of the abrupt truncation seen in most other galaxies, especially on the receding side. A total H I mass of 2.5 × 108 M☉ is derived, which gives an (MH I/LB) ≃ 8, making DDO 154 one of the most gas-rich galaxies known. The recovered H I flux makes it possible to extend the rotation curve by more than 33% in radii with the result that the rotation curve of DDO 154 is one of the most extensive rotation curves ever derived relative to the optical size of the galaxy. The new combined data confirm that the rotation curve is declining in the outer parts. Detailed mass models show that we may have reached the edge of the mass distribution for this galaxy, which would allow, for the first time, an estimate of the total mass and the total extent of a galaxy. For DDO 154, this gives an estimated total mass of Mtot ≃ 3.0 × 109 M☉ and an upper limit to the radial extent of Rtot ≤ 8 kpc.