标题： Sagittarius矮星系调查（SDGS）：对Sgr dSph恒星形成历史的约束 显示英文标题

标题： The Sagittarius Dwarf Galaxy Survey (SDGS): constraints on the Star Formation History of the Sgr dSph

摘要： 宽视场光度调查Sgr矮椭圆星系的主要特征简要介绍。 获得了约90000颗指向Sgr的恒星的V和I光度数据，以及约9000颗无Sgr恒星区域的恒星光度数据（用于去污染目的）。 这个大型数据库的全部潜力远未被完全探索。 在此我们仅介绍了统计去污染颜色-星等图分析的初步结果，试图建立Sgr星系恒星形成历史的框架。 提出了一种场景，即Sgr中的恒星形成开始于非常早期，并持续了几十亿年，伴随着星际介质（ISM）的逐步化学增丰。 大约80亿年前，恒星形成率突然下降，可能与导致星系气体耗尽的事件同时发生。 直到相对较近的时间（约10亿年前），恒星形成率一直保持非常低的水平。 显示英文摘要

摘要： The main characteristics of a wide photometric survey of the Sgr dwarf spheroidal galaxy are shortly presented. V and I photometry has been obtained for ~ 90000 stars toward Sgr and for ~ 9000 stars in a region devoid of Sgr stars (for decontamination purposes). The full potential of this large database is far from being completely explored. Here we present only preliminary results from the analysis of statistically decontaminated Color Magnitude Diagrams, trying to set a scheme of the Star Formation History of the Sgr Galaxy. A scenario is proposed in which star formation in Sgr began very early and lasted for several Gyr with progressive chemical enrichment of the Inter Stellar Medium (ISM). Nearly 8 Gyr ago the star formation rate abruptly decreased, perhaps in coincidence with the event that led to the gas depletion of the galaxy. A very small rate of star formation continued until relatively recent times (~ 1 Gyr ago).