arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.03059astro-ph.GA
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从星际极化的微分分析看银道面的磁场结构

Magnetic field structure of the Galactic plane from differential analysis of interstellar polarization

Tetsuya Zenko, Tetsuya Nagata, Mikio Kurita, Masaru Kino, Shogo Nishiyama, Noriyuki Matsunaga, Yasushi Nakajima

摘要:

本文提出了一种测量银道面全球磁场结构的新方法。我们已经确定了近红外偏振场恒星周围的52造父变星在最近的调查发现对银河平面。造父变星位于银河系外行星$-10^{\circ}\leq \, l\, \leq +10.5^{\circ}$和纬度$-0.22^{\circ}\leq \, l\, \leq +0.45^{\circ}$,它们与太阳的距离主要在10到15千秒差距之间。根据场星的偏振行为与$H-K_{\mathrm S}$颜色的关系,对视线进行了简单的分类,并给出了三种类型的典型实例。然后,分别用$Gaia$ DR 2星表、$H-K_{\mathrm S}$颜色直方图的峰值和与中心的造父变星的距离一致的$H-K_{\mathrm S}$颜色,将每个视线中的场星划分为(a)前景、(b)凸起和(c)背景。它们之间的差分分析使我们能够比仅仅依靠$H-K_{\mathrm S}$色差更明确地检查磁场结构。在一条视线中,磁场几乎平行于银河平面,并且从太阳一直到银河中心另一边的造父变星位置都是对齐的。然而,与我们的预想相反,在银河平面上,具有如此良好排列的磁场的视线数量相当少。至少有36个造父变星场表明随机磁场分量很重要。两个造父变星场表明磁场方向在视线上的变化超过45。每颜色变化的偏振增加$P$ /($H-K_{\mathrm S}$)随区域而变化,反映了磁场强度和湍流强度的比率的变化。

英文摘要:

A new method for measuring the global magnetic field structure of the Galactic plane is presented. We have determined the near-infrared polarization of field stars around 52 Cepheids found in recent surveys toward the Galactic plane. The Cepheids are located at the galactic longitudes $-10^{\circ}\leq \, l\, \leq +10.5^{\circ}$ and latitudes $-0.22^{\circ}\leq \, l\, \leq +0.45^{\circ}$, and their distances are mainly in the range of 10 to 15 kpc from the Sun. Simple classification of the sightlines is made with the polarization behavior vs. $H-K_{\mathrm S}$ color of field stars, and typical examples of three types are presented. Then, division of the field stars in each line of sight into (a) foreground, (b) bulge, and (c) background is made with the $Gaia$ DR2 catalog, the peak of the $H-K_{\mathrm S}$ color histogram, and $H-K_{\mathrm S}$ colors consistent with the distance of the Cepheid in the center, respectively. Differential analysis between them enables us to examine the magnetic field structure more definitely than just relying on the $H-K_{\mathrm S}$ color difference. In one line of sight, the magnetic field is nearly parallel to the Galactic plane and well aligned all the way from the Sun to the Cepheid position on the other side of the Galactic center. Contrary to our preconceived ideas, however, sightlines having such well-aligned magnetic fields in the Galactic plane are rather small in number. At least 36 Cepheid fields indicate random magnetic field components are significant. Two Cepheid fields indicate that the magnetic field orientation changes more than 45 in the line of sight. The polarization increase per color change $P$/ ($H-K_{\mathrm S}$) varies from region to region, reflecting the change in the ratio of the magnetic field strength and the turbulence strength.

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。

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