Distances to Galactic High-Velocity Clouds: Complex C
Distances to Galactic High-Velocity Clouds: Complex C
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DOI：
10.1086/524222
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
B. Wakker;D. York;J. Howk;J. Barentine;J. Barentine;R. Wilhelm;R. Peletier;H. V. Woerden;T. Beers;Ž. Ivezić;P. Richter;U. Schwarz;U. Schwarz
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文献类型：
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作者：
B. Wakker;D. York;J. Howk;J. Barentine;J. Barentine;R. Wilhelm;R. Peletier;H. V. Woerden;T. Beers;Ž. Ivezić;P. Richter;U. Schwarz;U. Schwarz
我们报告的第一个确定的距离括号的高速云（HVC）复杂的C。结合先前的测量结果显示，这片云的金属丰度是太阳的0.15倍，这些结果提供了充分的证据，证明复合物C追踪了落在银河系上的星系际气体的持续吸积。考虑到中性和电离的氢以及He，距离括号意味着质量为（3 - 14）× 106 M，而复合体的质量流入量为0.1 - 0.25 M yr-1。我们的距离支架上的蓝色水平分支（BHB）星星SDSS J120404.78 + 623345.6的光谱中的钙II吸收的检测，结合对BHB星星BS 16034 - 0114的一个显着的非检测。这些结果在到复合体C的距离上设定了3.7 - 11.2 kpc的强距离范围。从BHB星星BS 16079 - 0017的光谱中可以得到一个更弱的下限6.7 kpc。
We report the first determination of a distance bracket for the high-velocity cloud (HVC) complex C. Combined with previous measurements showing that this cloud has a metallicity of 0.15 times solar, these results provide ample evidence that complex C traces the continuing accretion of intergalactic gas falling onto the Milky Way. Accounting for both neutral and ionized hydrogen as well as He, the distance bracket implies a mass of (3-14) × 106 M☉, and the complex represents a mass inflow of 0.1-0.25 M☉ yr-1. We base our distance bracket on the detection of Ca II absorption in the spectrum of the blue horizontal branch (BHB) star SDSS J120404.78+623345.6, in combination with a significant nondetection toward the BHB star BS 16034-0114. These results set a strong distance bracket of 3.7-11.2 kpc on the distance to complex C. A more weakly supported lower limit of 6.7 kpc may be derived from the spectrum of the BHB star BS 16079-0017.