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The Minimum Amount of Stars a Galaxy Will Form

机译:星系将形成的最小恒星数量

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We present an analysis of the atomic hydrogen and stellar properties of 38 late-type galaxies in the local universe covering a wide range of H I mass-to-light ratios (/LB), stellar luminosities, and surface brightnesses. Combining the results with those of four other well-studied dwarf galaxies known for their unusually large H I contents, we identified an upper envelope for the /LB as a function of galaxy luminosity. This implies an empirical relation between the minimum amount of stars a galaxy will form and its initial baryonic mass. We also find that the star density systematically decreases with increasing /LB, making the galaxies optically more elusive. While the stellar mass of a galaxy seems to be only loosely connected to its baryonic mass, the latter quantity is strongly linked to the galaxy's dynamical mass as it is observed in the baryonic Tully-Fisher relation. We find that dwarf irregular galaxies with generally high /LB ratios follow the same trend as defined by lower /LB giant galaxies but are underluminous for their rotation velocity to follow the trend in a stellar mass Tully-Fisher relation, suggesting that the baryonic mass of the dwarf galaxies is normal but they have failed to produce a sufficient amount of stars. Finally, we present a three-dimensional equivalent to the morphology-density relation which shows that high /LB galaxies preferentially evolve and/or survive in low-density environments. We conclude that an isolated galaxy with a shallow dark matter potential can retain a large portion of its baryonic matter in the form of gas, only producing the minimum quantity of stars necessary to maintain a stable gas disk.
机译:我们对本地宇宙中38个晚型星系的原子氢和恒星性质进行了分析,涵盖了范围广泛的H I质光比(/ LB),恒星光度和表面亮度。将结果与其他四个经过充分研究的矮星系(以其异常大的H I含量而闻名)的结果相结合,我们确定了/ LB的上限,它是星系光度的函数。这意味着星系将形成的最小恒星数量与其初始重子质量之间存在经验关系。我们还发现,随着/ LB的增加,恒星密度会系统地降低,从而使星系在光学上更加难以捉摸。虽然银河系的恒星质量似乎只是与它的重子质量松散地联系在一起,但是从重音塔利-费舍关系中可以看出,后者的数量与星系的动态质量有很强的联系。我们发现,通常具有高/ LB比值的矮不规则星系遵循与较低/ LB巨星系定义的趋势相同的趋势,但是其旋转速度低于恒星质量Tully-Fisher关系的光速,表明该星系的重子质量矮星系是正常的,但它们未能产生足够数量的恒星。最后,我们提出了一个等效于形态密度关系的三维模型,该关系表明高/ LB星系优先在低密度环境中进化和/或生存。我们得出的结论是,具有浅暗物质势能的孤立星系可以以气体形式保留其大部分重子物质,仅产生维持稳定气盘所需的最小恒星。

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