arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2108.01905astro-ph.GA
收藏

发现银河系中最大的气体细丝,还是一个新的旋臂?

The discovery of the largest gas filament in our Galaxy, or a new spiral arm?

Chong Li, Keping Qiu, Bo Hu, Yue Cao

摘要:

利用500米口径球面射电望远镜(FAST),我们在307 $.\!\!^{\circ}$ 7 $<$ $<$ 311 $.\!\!^{\circ}$ 0和40 $.\!\!^{\circ}$ 9 $<$ $δ$ $<$ 43 $.\!\!^{\circ}$ 4的天区探测到一个巨大的HI记录结构。该结构的速度范围为$-$ 170 km s $^{-1}$至$-$ 130 km s $^{-1}$,平均速度为$-$ 150 km s $^{-1}$,使其银心距离为22 kpc。HI结构的长度为1.1 kpc,这似乎是迄今为止银河系中最远和最大的巨灯丝,我们将其命名为Cattail。其质量计算为6.5 $\times$ 10 $^4$ M $_{\odot}$,线性质量密度为60 M $_{\odot}$ pc $^{-1}$。它的宽度为207 pc,对应的长宽比为5:1。香蒲沿其长轴具有较小的速度梯度(0.02 km s $^{-1}$ pc $^{-1}$)。结合HI 4PI数据,我们发现香蒲可能具有更大的长度,高达5 kpc。我们还确定了另一个新的细长结构是延伸到银河系第一象限的外盾-半人马座(OSC)臂,香蒲似乎位于远远落后的OSC。关于这样一个巨大的灯丝是如何在银河系的极端位置产生的问题仍然悬而未决。或者,香蒲可能是OSC之外的一个新手臂的一部分,尽管令人困惑的是,这个结构并不完全遵循银河系圆盘的翘曲。

英文摘要:

Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we detect a giant HI filamentary structure in the sky region of 307$.\!\!^{\circ}$7 $<$ $α$ $<$ 311$.\!\!^{\circ}$0 and 40$.\!\!^{\circ}$9 $<$ $δ$ $<$ 43$.\!\!^{\circ}$4. The structure has a velocity range of $-$170 km s$^{-1}$ to $-$130 km s$^{-1}$, and a mean velocity of $-$150 km s$^{-1}$, putting it to a Galactocentric distance of 22 kpc. The HI structure has a length of 1.1 kpc, which appears to be so far the furthest and largest giant filament in the Galaxy and we name it Cattail. Its mass is calculated to be 6.5 $\times$ 10$^4$ M$_{\odot}$ and the linear mass density is 60 M$_{\odot}$ pc$^{-1}$. Its width is 207 pc, corresponding to an aspect ratio of 5:1. Cattail possesses a small velocity gradient (0.02 km s$^{-1}$ pc$^{-1}$) along its major axis. Together with the HI4PI data, we find that Cattail could have an even larger length, up to 5 kpc. We also identify another new elongated structure to be the extension into the Galactic first quadrant of the Outer Scutum-Centaurus (OSC) arm, and Cattail appears to be located far behind the OSC. The question about how such a huge filament is produced at the extreme Galactic location remains open. Alternatively, Cattail might be part of a new arm beyond the OSC, though it is puzzling that the structure does not fully follow the warp of the Galactic disk.

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。

↑