论文标题
Sloan Digital Sky Survey的堆叠光谱的星形超湿星系的课程
Lessons on Star-forming Ultra-diffuse Galaxies from The Stacked Spectra of Sloan Digital Sky Survey
论文作者
论文摘要
我们通过从斯隆数字天空调查中堆叠光谱，研究了位于低密度环境中的28个恒星超湿星系（UDGS）的体内属性。这些相对分离的UDGS，具有$ \ log_ {10}（m _*/m _*/m _ {\ odot}）\ sim 8.57 \ pm0.29 $的恒星群体具有持续水平的总静脉 - 固定级 - 股票[m/h] -1.00 \ pm0.16 $，恒星年龄$ t _*\ sim5.2 \ pm0.5 $ gyr，$α$ - 增强[$α$/fe] $ \ sim 0.24 \ pm0.10 $，和氧气含量12+log（o/h） $ 54 \ pm12 $ km/s。在恒星形成率与恒星质量图上，这些UDG的位置低于从大型螺旋中的推断恒星形成的主序列，但大致遵循低表面 - 亮度矮星系的主要序列。我们发现，与附近典型矮人的金属质量关系相比，这些恒星形成的UDG并不是其恒星质量的金属贫困或金属富裕。借助这项工作和先前研究的UDG数据，我们还发现[fe/h]和镁元素增强[mg/fe] [mg/fe]的UDGS：[mg/fe] $ \ simeq-0.43（\ pm0.26）$ \ simeq-0.43（\ pm0.26）$ [fe/h] $ [fe/h]
We investigate the on-average properties for 28 star-forming ultra-diffuse galaxies (UDGs) located in low-density environments, by stacking their spectra from the Sloan Digital Sky Survey. These relatively-isolated UDGs, with stellar masses of $\log_{10}(M_*/M_{\odot})\sim 8.57\pm0.29$, have the on-average total-stellar-metallicity [M/H]$\sim -0.82\pm0.14$, iron-metallicity [Fe/H]$\sim -1.00\pm0.16$, stellar age $t_*\sim5.2\pm0.5$ Gyr, $α$-enhancement [$α$/Fe]$\sim 0.24\pm0.10$, and oxygen abundance 12+log(O/H)$\sim 8.16\pm0.06$, as well as central stellar velocity dispersion $54\pm12$ km/s. On the star-formation rate versus stellar mass diagram, these UDGs are located lower than the extrapolated star-forming main sequence from the massive spirals, but roughly follow the main sequence of low-surface-brightness dwarf galaxies. We find that these star-forming UDGs are not particularly metal-poor or metal-rich for their stellar masses, as compared with the metallicity-mass relations of the nearby typical dwarfs. With the UDG data of this work and previous studies, we also find a coarse correlation between [Fe/H] and magnesium-element enhancement [Mg/Fe] for UDGs: [Mg/Fe]$\simeq-0.43(\pm0.26)$[Fe/H]$-0.14(\pm0.40)$.
