Tracing the stellar component of low surface brightness Milky Way dwarf galaxies to their outskirts
Tracing the stellar component of low surface brightness Milky Way dwarf galaxies to their outskirts
复制标题
追踪低表面亮度银河系矮星系的恒星成分到其郊区
DOI：
10.1051/0004-6361/201731450
复制
发表时间：
2017
影响因子：
6.5
通讯作者：
N. Fernando
中科院分区：
文献类型：
--
作者：
L. Cicuéndez;G. Battaglia;M. Irwin;J. Bermejo;B. McMonigal;N. Bate;G. Lewis;A. Conn;T. D. Boer;C. Gallart;M. Guglielmo;R. Ibata;A. McConnachie;E. Tolstoy;N. Fernando
目标。我们介绍了在六分仪矮球状星系周围进行的深度和空间扩展的CTIO/DECam g和r测光的结果（延伸到最古老的主序列关闭点以下2等，覆盖范围类似于20度）。我们的目标是使用这个数据集来研究六分仪整体恒星种群及其成员恒星在不同演化阶段的结构特性，以及寻找银河系潮汐扰动的可能迹象，这将表明偏离动力学平衡。方法.我们通过将贝叶斯蒙特卡罗马尔可夫链方法应用于单个恒星的位置，对六分仪的恒星成分进行了迄今为止最准确和定量的结构分析。表面密度图是建立统计净化样品通过匹配滤波器分析的颜色-幅度图，然后分析偏离轴对称。结果六分仪被发现是显着的空间扩展和更集中的比早期的研究建议。没有发现统计上显著的失真或潮汐扰动的迹象，直到V波段的表面亮度极限接近31.8 mag/arcsec（2）。我们确定了一个过密的中心区域，可能对应于以前报道的运动学子结构（S）。与先前的发现一致，像蓝色水平分支星这样的老的和贫金属的恒星比其他演化阶段的恒星覆盖更大的区域，而明亮的蓝色离散星（BS）比暗淡的恒星在空间上延伸得更少。然而，明亮和暗淡BS的不同空间分布似乎与六分仪的恒星组成部分中发现的一般年龄和金属丰度梯度一致。这与六分仪BS是由双星演化而成的，并不一定是由于存在一个中心被破坏的球状星团，如文献中所建议的那样。我们提供的结构参数分析的各种人群，并公开提供的光度目录的点源，以及目录的文献光谱测量与更新的成员概率。
Aims. We present results from deep and very spatially extended CTIO/DECam g and r photometry (reaching out to similar to 2 mag below the oldest main-sequence turn-off and covering similar to 20 deg(2)) around the Sextans dwarf spheroidal galaxy. We aim to use this dataset to study the structural properties of Sextans overall stellar population and its member stars in different evolutionary phases, as well as to search for possible signs of tidal disturbance from the Milky Way, which would indicate departure from dynamical equilibrium. Methods. We performed the most accurate and quantitative structural analysis to-date of Sextans' stellar components by applying Bayesian Monte Carlo Markov chain methods to the individual stars' positions. Surface density maps are built by statistically decontaminating the sample through a matched filter analysis of the colour-magnitude diagram, and then analysed for departures from axisymmetry. Results. Sextans is found to be significantly less spatially extended and more centrally concentrated than early studies suggested. No statistically significant distortions or signs of tidal disturbances were found down to a surface brightness limit of similar to 31.8 mag/arcsec(2) in V-band. We identify an overdensity in the central regions that may correspond to previously reported kinematic substructure(s). In agreement with previous findings, old and metal-poor stars such as Blue Horizontal Branch stars cover a much larger area than stars in other evolutionary phases, and bright Blue Stragglers (BSs) are less spatially extended than faint ones. However, the different spatial distribution of bright and faint BSs appears consistent with the general age and metallicity gradients found in Sextans' stellar component. This is compatible with Sextans BSs having formed by evolution of binaries and not necessarily due to the presence of a central disrupted globular cluster, as suggested in the literature. We provide structural parameters for the various populations analysed and make publicly available the photometric catalogue of point-sources as well as a catalogue of literature spectroscopic measurements with updated membership probabilities.
影响因子：
4.8
作者：
N. Bate;N. Bate;B. McMonigal;G. F. Lewis;M. Irwin;E. González-Solares;T. Shanks;Nigel Metcalfe-Nigel-Metc
通讯作者：
N. Bate;N. Bate;B. McMonigal;G. F. Lewis;M. Irwin;E. González-Solares;T. Shanks;Nigel Metcalfe-Nigel-Metc
DOI：
10.1088/2041-8205/761/2/l31
发表时间：
2012-11
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
G. Battaglia;M. Irwin;E. Tolstoy;T. de Boer;M. Mateo
通讯作者：
G. Battaglia;M. Irwin;E. Tolstoy;T. de Boer;M. Mateo