Surface Brightness Fluctuation Distances to Dwarf Elliptical Galaxies in the Sculptor Group
Surface Brightness Fluctuation Distances to Dwarf Elliptical Galaxies in the Sculptor Group
复制标题
玉夫座星系团中矮椭圆星系的表面亮度涨落距离
DOI：
10.1086/300635
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
B. Binggeli
中科院分区：
文献类型：
--
作者：
H. Jerjen;K. Freeman;B. Binggeli
作为正在进行的在本星系群附近寻找矮椭圆星系（dE's）的一部分（Jerjen等人），我们获得了根据Sculptor（Scl）群区域中的形态学标准鉴定的五个dE候选者的深B和R带图像。我们进行了表面亮度波动（SBF）的R波段图像上的分析，以测量每个dE的表观波动幅度R。利用恒星星族合成模型（Worthey）的预测，得到的R值在-1.17和-1.13之间的狭窄范围内，确定了星系的距离。所有这些dE候选人都是Scl集团主要成员的卫星。对dE候选星系ESO 294-010的红移测量独立地证实了它的星系群成员身份：来自小H II区域的[O III]和Hα发射线给出了117（±5）km s-1的日心速度，与其母星系NGC 55的速度（v = 125 km s-1）非常一致。SBF距离的精确度（5%-10%）有助于描绘Scl群成员的雪茄状分布，其延伸距离从1.7到4.4 Mpc，并集中在三个，可能是四个子块中。9个Scl星系的哈勃图，包括我们的两个dE的，表现出紧密的线性速度-距离的关系与陡峭的斜率为119公里s-1 Mpc-1。结果表明，Scl群成员之间的引力相互作用在群的动力学中只起很小的作用。然而，整个系统的哈勃流似乎受到我们银河系和M31的大质量的强烈干扰，这导致了观察到的剪切运动。从位于本星系群和朝向Scl星系群的49个星系的距离和速度，我们说明了星系分布的连续性，这有力地支持了两个星系群形成单一超星系结构的观点。
As part of an ongoing search for dwarf elliptical galaxies (dE's) in the vicinity of the Local Group (Jerjen et al.), we acquired deep B- and R-band images for five dE candidates identified on morphological criteria in the Sculptor (Scl) group region. We carried out a surface brightness fluctuation (SBF) analysis on the R-band images to measure the apparent fluctuation magnitude R for each dE. Using predictions from stellar population synthesis models (Worthey) giving R values in the narrow range between -1.17 and -1.13, the galaxy distances were determined. All of these dE candidates turned out to be satellites of Scl group major members. A redshift measurement of the dE candidate ESO 294-010 yielded an independent confirmation of its group membership: the [O III] and Hα emission lines from a small H II region gave a heliocentric velocity of 117 (±5) km s-1, in close agreement with the velocity of its parent galaxy NGC 55 (v⊙ = 125 km s-1). The precision of the SBF distances (5%–10%) contributes to delineating the cigar-like distribution of the Scl group members, which extend over distances from 1.7 to 4.4 Mpc and are concentrated in three, possibly four subclumps. The Hubble diagram for nine Scl galaxies, including two of our dE's, exhibits a tight linear velocity-distance relation with a steep slope of 119 km s-1 Mpc-1. The results indicate that gravitational interaction among the Scl group members plays only a minor role in the dynamics of the group. However, the Hubble flow of the entire system appears strongly disturbed by the large masses of our Galaxy and M31, which leads to the observed shearing motion. From the distances and velocities of 49 galaxies located in the Local Group and toward the Scl group, we illustrate the continuity of the galaxy distribution, which strongly supports the view that the two groups form a single supergalactic structure.