arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0904.1003astro-ph.GA
收藏

第7期SDSS数据发布中的Halo流

Halo streams in the 7th SDSS data release

R. Klement, H. -W. Rix, C. Flynn, B. Fuchs, T. C. Beers, C. Allende Prieto, D. Bizyaev, H. Brewington, Y. S. Lee, E. Malanushenko, V. Malanushenko, D. Oravetz, … 展开作者

R. Klement, H. -W. Rix, C. Flynn, B. Fuchs, T. C. Beers, C. Allende Prieto, D. Bizyaev, H. Brewington, Y. S. Lee, E. Malanushenko, V. Malanushenko, D. Oravetz, K. Pan, P. Re Fiorentin, A. Simmons, S. Snedden

摘要:

我们使用斯隆数字巡天(SDSS)第7次公开数据发布的数据检测了太阳附近的恒星晕流,其中包括定向恒星计划SEGUE:斯隆银河系理解和探索扩展。为了获得到每颗恒星的距离,我们使用了Ivezic等人(2008)的金属度依赖光度视差关系,我们检查并量化了准确性。我们的最终样本由22,321颗附近(d < 2 kpc),贫金属([Fe/H] < -0.5)的主序星组成,具有6D的位置和空间速度估计。我们通过合适的运动学代理的运动,角动量,偏心率和轨道极角的“有效”积分的特点,这些恒星的轨道,并比较所观察到的分布的期望从一个平滑的分布在四个[Fe/H]箱。在此基础上,我们确定至少有五个显着的“相空间overdensities”的恒星非常相似的轨道在太阳附近,我们可以分配明确的峰值[Fe/H]分布。其中三个以前已经确定,包括Helmi等人(1999)在12.0的显著性水平上发现的晕流。此外,我们发现至少有两个新的真正的晕流,判断他们的运动学和[Fe/H],在显着水平分别为2.9和4.8。对于一个星流,恒星甚至在配置空间中表现出一致性,与Julic等人(2008)在(R,z)\approx(9.5,0.8)kpc发现的恒星空间过密度相匹配。我们的研究结果表明,我们的搜索方法的实用功能,以检测附近的恒星的相空间分布的子结构,而不作先验假设的详细形式的引力势。

英文摘要:

We have detected stellar halo streams in the solar neighborhood using data from the 7th public data release of the Sloan Digital Sky Survey (SDSS), which includes the directed stellar program SEGUE: Sloan Extension For Galactic Understanding and Exploration. In order to derive distances to each star, we used the metallicity-dependent photometric parallax relation from Ivezic et al. (2008) for which we examine and quantify the accuracy. Our final sample consists of 22,321 nearby (d < 2 kpc), metal-poor ([Fe/H] < -0.5) main-sequence stars with 6D estimates of position and space velocity. We characterize the orbits of these stars through suitable kinematic proxies for their "effective" integrals of motion, angular momentum, eccentricity, and orbital polar angle and compare the observed distribution to expectations from a smooth distribution in four [Fe/H] bins. On this basis we identify at least five significant "phase-space overdensities" of stars on very similar orbits in the solar neighborhood to which we can assign unambiguously peaked [Fe/H] distributions. Three of them have been identified previously, including the halo stream discovered by Helmi et al. (1999) at a significance level of 12.0. In addition, we find at least two new genuine halo streams, judged by their kinematics and [Fe/H], at significance levels of 2.9 and 4.8, respectively. For one stream the stars even show coherence in configuration space, matching a spatial overdensity of stars found by Juric et al. (2008) at (R,z) \approx (9.5,0.8) kpc. Our results demonstrate the practical power of our search method to detect substructure in the phase-space distribution of nearby stars without making a-priori assumptions about the detailed form of the gravitational potential.

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。

↑