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تسجيل مستخدم جديدDiscovery of diffuse optical emission lines from the inner Galaxy: Evidence for LI(N)ER-like gas
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Optical emission lines are used to categorize galaxies into three groups according to their dominant central radiation source: active galactic nuclei, star formation, or low-ionization (nuclear) emission regions [LI(N)ERs] that may trace ionizing radiation from older stellar populations. Using the Wisconsin H-Alpha Mapper, we detect optical line emission in low-extinction windows within eight degrees of Galactic Center. The emission is associated with the 1.5-kiloparsec-radius Tilted Disk of neutral gas. We modify a model of this disk and find that the hydrogen gas observed is at least $48%$ ionized. The ratio [NII] $lambda$6584 $overset{lower.5emcirc}{mathrm{A}}$/H$alpha$ $lambda$6563 $overset{lower.5emcirc}{mathrm{A}}$ increases from 0.3 to 2.5 with Galactocentric radius; [OIII] $lambda$5007 $overset{lower.5emcirc}{mathrm{A}}$ and H$beta$ $lambda$4861 $overset{lower.5emcirc}{mathrm{A}}$ are also sometimes detected. The line ratios for most Tilted Disk sightlines are characteristic of LI(N)ER galaxies.
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