EUV mapping of the local interstellar medium: the Local Chimney revealed?
EUV mapping of the local interstellar medium: the Local Chimney revealed?
复制标题
当地星际介质的 EUV 测绘：当地烟囱显露出来？
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
R. Lallement
中科院分区：
文献类型：
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作者：
B. Welsh;D. Sfeir;M. Sirk;R. Lallement
我们讨论了由EUVE卫星探测到的450个具有可靠距离估计的源的星系分布。晚型恒星在附近的EUV源分布中占主导地位，而距离为>；100pc的EUV源探测到的大部分是热白矮星。所有这些源的银河系分布是不均匀的，在参宿四星系团、沿CMa星际隧道的视线内以及在两个半球的高银河系纬度上都可以看到数目的增加。将这些EUV源的分布与由Sfeir等人的星际NaI观测得到的局部泡沫区的中性吸收边界的分布进行了比较。(1999)揭示，绝大多数极紫外光源都被限制在这一中性边界内。然而，在银河系高纬度，沿着低中性柱密度的视线探测到了20个河外EUV源，这与银河晕中的局部星际空穴是开放的一致。这个“局部烟囱”朝高纬度0.25keV软X射线背景辐射强度增强的两个区域开放。尽管热的局部气泡气体仍然包含在银河系平面中冷中性的星际气体边界内，但它很可能已经扩展到光晕中，产生了局部烟囱特征。
We discuss the galactic distribution of 450 sources detected by the EUVE satellite that have reliable distance es- timates. Late-type stars dominate the nearby EUV source dis- tribution, whereas the majority of EUV source detections with distances > 100pc are hot white dwarf stars. The galactic dis- tribution of all these sources is non-uniform with number en- hancements seen towards the Hyades cluster, in line-of-sight along theCMa interstellar tunnel and towards high galactic latitudes in both hemispheres. A comparison of the distribution of these EUV sources with that of the neutral absorption bound- ary of the Local Bubble region derived from the interstellar NaI observations of Sfeir et al. (1999) reveals that vast majority of EUV sources are contained within this neutral boundary. How- ever, at high galactic latitudes 20 extragalactic EUV sources have been detected along lines-of-sight with low neutral column density, and is consistent with the local interstellar cavity being "open-ended" in the galactic halo. This "Local Chimney" opens towards two regions of enhanced intensity of the 0.25 keV soft X-ray background emission at high galactic latitudes. Although the hot Local Bubble gas is still contained within a cold, neutral interstellar gas boundary in the galactic plane, it has probably expanded into the halo to produce the Local Chimney feature.