论文标题
PA $β$，H $α$，以及NGC 5194和NGC 6946的衰减
Pa$β$, H$α$, and Attenuation in NGC 5194 and NGC 6946
论文作者
论文摘要
我们将Hubble太空望远镜（HST）Paschen $β$（PA $β$）与地面的，以前出版的H $α$地图发表，以估计影响H $α$α$，A（H $α$）的衰减，在附近，面对面的Galaxies NGC 5194和NGC 694和Ngc 6946 $ aStimate 2 $ natimate ngcimations ngc 6946。每个星系中的PC直径孔都跨越了两个星系中的半径范围，a（h $α$）的半径是半径的，尽管详细范围较高，但较高的衰减内部区域均具有最高的n $ luminin $ luminin $α$α$。这不是我们数据的良好预测因素，与以前的工作相一致，我们可以预测A（H $α$）的好工作加上分子气柱密度，n（h）也可以预测（H $α$），我们表明，对于银河系的气体到粉尘值的预期范围是〜0.2倍，可以将A（H $α$）解释为n（h）的函数（H $α$）。
We combine Hubble Space Telescope (HST) Paschen $β$ (Pa$β$) imaging with ground-based, previously published H$α$ maps to estimate the attenuation affecting H$α$, A(H$α$), across the nearby, face-on galaxies NGC 5194 and NGC 6946. We estimate A(H$α$) in ~ 2,000 independent 2" ~75 pc diameter apertures in each galaxy, spanning out to a galactocentric radius of almost 10 kpc. In both galaxies, A(H$α$) drops with radius, with a bright, high attenuation inner region, though in detail the profiles differ between the two galaxies. Regions with the highest attenuation-corrected H$α$ luminosity show the highest attenuation, but the observed H$α$ luminosity of a region is not a good predictor of attenuation in our data. Consistent with much previous work, the IR-to-H$α$ color does a good job of predicting A(H$α$). We calculate the best-fit empirical coefficients for use combining H$α$ with 8, 12, 24, 70, or 100 $μ$m to correct for attenuation. These agree well with previous work but we also measure significant scatter around each of these linear relations. The local atomic plus molecular gas column density, N(H), also predicts A(H$α$) well. We show that a screen with magnitude ~ 0.2 times the expected for a Milky Way gas-to-dust value does a reasonable job of explaining A(H$α$) as a function of N(H). This could be expected if only ~ 40% of gas and dust directly overlap regions of H$α$ emission.
