The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubble
M. Galeazzi, M. Chiao, M. R. Collier, T. Cravens, D. Koutroumpa, K. D. Kuntz, R. Lallement, S. T. Lepri, D. McCammon, K. Morgan, F. S. Porter, I. P. Robertson, … 展开作者
M. Galeazzi, M. Chiao, M. R. Collier, T. Cravens, D. Koutroumpa, K. D. Kuntz, R. Lallement, S. T. Lepri, D. McCammon, K. Morgan, F. S. Porter, I. P. Robertson, S. L. Snowden, N. E. Thomas, Y. Uprety, E. Ursino, B. M. Walsh
备注：
9 pages, 6 figures, 1 table. The final version of the paper is available on Nature
The Solar neighborhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily-absorbed 1/4 keV X rays, coupled with the discovery that interstellar space within ~100 pc of the Sun is almost completely devoid of cool absorbing gas led to a picture of a "local cavity" filled with X-ray emitting hot gas dubbed the local hot bubble. This model was recently upset by suggestions that the emission could instead be produced readily within the solar system by heavy solar wind ions charge exchanging with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the existence of million-degree gas within the Galactic disk. Here we report results showing that the total solar wind charge exchange contribution is 40% +/- 5% (stat) +/- 5% (sys) of the 1/4 keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble of order 100 pc extent surrounding the Sun.
A formation mechanism for the large plumes in the prominence
为了理解太阳耀斑中大羽流的形成机制，我们研究了两种太阳耀斑中大羽流现象的形成过程。我们利用新真空太阳望远镜、太阳动力学天文台和日地关系天文台的观测资料研究了两个大羽流的动力学和热性质。我们发现，两个大的高分辨率数据观测到的羽流是相当不同的，从以前研究的小尺度羽流。它们诞生于一个投影面积为10-20 Mm^2的日珥泡的顶部。在每一个大的羽流出现之前，气泡膨胀并呈现出准半圆形的外观。同时，气泡中的极紫外（EUV）波段的发射强度增加。一个小规模的灯丝被发现在第二个大的羽流爆发的气泡。当气泡的高度与气泡宽度的一半相当时，气泡变得不稳定并产生羽流。在羽流形成过程中，由相反的多普勒信号控制的气泡顶部的两个侧边缘彼此接近。然后，大的羽流出现，并以大约13-15公里/秒的恒定速度继续上升。这两个大的羽状物的温度为1.3 x 10^6开尔文，密度为2.0 x 10^9 cm^-3，比典型的日珥高两个数量级，密度低一个数量级。我们还发现，气泡是一个热的，低密度的体积，而不是一个空的区域下面的冷和密集的突出。因此，我们的结论是，这两个大的羽状物是由热压力的增强引发的日珥气泡破裂的结果;它们从气泡中分离出来，最有可能是通过磁重联。
Formation and X-ray emission from hot bubbles in planetary nebulae - III. The impact of [Wolf-Rayet]-type winds
Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学无线电天文学与天体物理研究所）；Instituto de Astrofísica de Andalucía, CSIC（安达卢西亚天体物理研究所，西班牙高等科学研究委员会）；Fakultät für Physik, Universität Duisburg-Essen（杜伊斯堡-埃森大学物理学院）
Low-mass stars dominate the hot (0.7 keV) Galactic X-ray emission
Osservatorio Astronomico di Brera, (INAF)（布雷拉天文台（意大利国家天体物理研究所））；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；Como Lake Center for Astrophysics (CLAP), DiSAT, Università degli Studi dell’Insubria（因苏布里亚大学DiSAT系科莫湖天体物理学中心）；Institut für Astronomie & Astrophysik, Eberhard Karls Universität Tübingen（蒂宾根大学天文与天体物理研究所）；Dr. Karl Remeis Observatory, Erlangen（埃尔朗根卡尔·雷梅斯观测站）
