在暗能量巡天中发现波江座-凤凰座的恒星超密度
Discovery of a Stellar Overdensity in Eridanus-Phoenix in the Dark Energy Survey
摘要：
本文报道了在暗能量巡天（DES）的第一年观测数据中，在波江座和凤凰座方向上发现了过量的主序星。Eridanus-Phoenix（EriPhe）的过密度集中在l~285度和b~-60度附近，并且在经度上跨越至少30度，在纬度上跨越10度。检测的泊松显著性至少为9 sigma。过密区的恒星星族在亮度和颜色上与附近的球状星团NGC 1261相似，表明EriPhe的日心距离约为d~16 kpc。因此，EriPhe在投影中的范围至少为~ 4kpc乘~3 kpc。在天空中，这个高密度位于NGC 1261和DES在类似的日心距离发现的新恒星流之间，即所谓的凤凰流。考虑到它们彼此相似的距离和接近度，这三个结构可能在运动学上相关联。另外，EriPhe的超密度在形态上类似于室女座的超密度和武仙座-天鹰座云，它们也位于类似的银河系中心距离。这三个超密度位于极平面上，相隔约120度，可能有一个共同的原点。需要对EriPhe中的恒星进行光谱跟踪观测，以充分了解这种过度密度的性质。
英文摘要：
We report the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first year data of the Dark Energy Survey (DES). The Eridanus-Phoenix (EriPhe) overdensity is centered around l~285 deg and b~-60 deg and spans at least 30 deg in longitude and 10 deg in latitude. The Poisson significance of the detection is at least 9 sigma. The stellar population in the overdense region is similar in brightness and color to that of the nearby globular cluster NGC 1261, indicating that the heliocentric distance of EriPhe is about d~16 kpc. The extent of EriPhe in projection is therefore at least ~4 kpc by ~3 kpc. On the sky, this overdensity is located between NGC 1261 and a new stellar stream discovered by DES at a similar heliocentric distance, the so-called Phoenix Stream. Given their similar distance and proximity to each other, it is possible that these three structures may be kinematically associated. Alternatively, the EriPhe overdensity is morphologically similar to the Virgo overdensity and the Hercules-Aquila cloud, which also lie at a similar Galactocentric distance. These three overdensities lie along a polar plane separated by ~120 deg and may share a common origin. Spectroscopic follow-up observations of the stars in EriPhe are required to fully understand the nature of this overdensity.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
