arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0909.1349astro-ph.CO
收藏

SDSS J092609 .45+334304.1:一个邻近的未演化星系

SDSS J092609.45+334304.1: a nearby unevolved galaxy

S. A. Pustilnik, A. L. Tepliakova, A. Y. Kniazev, J. -M. Martin, A. N. Burenkov

摘要:

本文给出了对极低表面亮度矮星系SDSS J092609.45+334304.1的观测结果,其极端参数表明该星系处于未演化状态。也就是说,它的O/H值,作为在盘的NE边缘处的两个相邻HII区域中的O/H值的平均值导出,对应于参数12+log(O/H)=7.12+-0.02,这是已知的两个最低值之一。用Nancay射电望远镜测量的HI总通量和测光结果表明,该星系的M(HI)/L_B值约为3.0,是局域体积中已知的最高值之一。该星系位于附近一个被称为Lynx-Cancer空洞的低密度区域,其中已知存在其他未演化的星系,包括DDO 68,HS 0832+3542和SAO 0822+3545。这个几乎是边对边的VLSB星系的总质量是其重子质量的8.3倍,这意味着暗物质(DM)晕的动力学主导地位。该星系外部的(u-g)、(g-r)颜色与其主要恒星星族的年龄一致,为1- 3 Gyr。由于星系的孤立性,当前或最近的恒星形成(SF)的影响很小,它的接近和相当大的HI流量(~2.5 Jy km/s),这个VLSB矮星是一个很好的实验室,通过HI运动学和非常贫金属的低表面密度环境中的恒星形成过程的详细研究DM晕的性质。这一发现,以及在这个空洞中发现的其他不寻常的矮星系,为星系演化与其重子质量范围为10^{8}至10^{9} Mo的极低密度环境之间的关系提供了证据。这种关系似乎与星系和结构形成的LambdaCDM模型中的预期一致。

英文摘要:

We present the results of observations of the very low surface brightness (VLSB) dwarf galaxy SDSS J092609.45+334304.1 with extreme parameters which indicate its unevolved status. Namely, its value of O/H, derived as an average of that in two adjacent HII regions at the NE edge of the disc, corresponds to the parameter 12+log(O/H)=7.12+-0.02, which is amongst two lowest known. The total HI flux measurement obtained with the Nancay Radio Telescope and the photometric results imply that the galaxy ratio M(HI)/L_B ~3.0, is among the top known in the Local Volume. The galaxy is situated in the region of a nearby underdense region known as the Lynx-Cancer void, where other, unevolved galaxies, including DDO 68, HS 0832+3542 and SAO 0822+3545, are known to be present. The total mass of this almost edge-on VLSB galaxy is ~8.3 times larger than its baryonic mass, implying the dynamical dominance of Dark Matter (DM) halo. The (u-g), (g-r) colours of outer parts of this galaxy are consistent with the ages of its main stellar population of 1--3 Gyr. Thanks to the galaxy isolation, the small effect of current or recent star formation (SF), its proximity and rather large HI flux (~2.5 Jy km/s), this VLSB dwarf is a good laboratory for the detailed study of DM halo properties through HI kinematics and the star formation processes in very metal-poor low surface density environment. This finding, along with the discovery of other unusual dwarf galaxies in this void, provides evidence for the relation between galaxy evolution and its very low-density environment for the baryonic mass range of 10^{8} to 10^{9} Mo. This relation seems to be consistent with that expected in the LambdaCDM models of galaxy and structure formation.

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。

↑