论文标题
冥王星的紫外光谱，表面反射率和气流排放
Pluto's Ultraviolet Spectrum, Surface Reflectance, and Airglow Emissions
论文作者
论文摘要
在新的地平线航天器与冥王星相遇期间，爱丽丝紫外线光谱仪进行了一系列观察结果，这些观察结果检测到了星际介质（IPM）和冥王星的排放。在冥王星的方向上，发现IPM在Lyman $α$，0.24 $ \ pm $ 0.02R $ 0.02R的Lyman $β$中的IPM为133.4 $ \ pm $ 0.6R，在He I584Å处<0.10r。我们分析了在冥王星最近的最接近方法之前获得的3,900个数据，并检测了来自冥王星磁盘上方的H I，N I，N II，N $ _2 $的气流排放。我们发现冥王星在Lyman $α$上的亮度为$ 29.3 \ pm1.9 $ r，与前持续估计非常吻合。在1085Å处检测N II多重组是对冥王星大气中离子的第一个直接检测。我们没有检测到来自贵族气体的任何排放，并在AR I1048Å线的亮度上放置3 $σ$上限为0.14 r。我们将根据我们自己的气球模型的预测和预测，基于从新视野观察到的太阳掩型得出的大气轮廓和冥王星气流的亮度。尽管在Lyman $α$上完全不透明，但冥王星的大气在超过1425Å的波长上是光学薄的。因此，大量的太阳能FUV光到达表面，可以参与空间风化过程。从冥王星反射的阳光的亮度来看，我们发现表面的反射率因子（I/F）在1400-1850Å之间的17％。我们还以〜5 $ \ times10^{15} $ cm $ $^{ - 2} $的柱密度的吸收为c $ _3 $ hydocaracety，甲基乙炔的第一次检测。
During the New Horizons spacecraft's encounter with Pluto, the Alice ultraviolet spectrograph conducted a series of observations that detected emissions from both the interplanetary medium (IPM) and Pluto. In the direction of Pluto, the IPM was found to be 133.4$\pm$0.6R at Lyman $α$, 0.24$\pm$0.02R at Lyman $β$, and <0.10R at He I 584Å. We analyzed 3,900s of data obtained shortly before closest approach to Pluto and detect airglow emissions from H I, N I, N II, N$_2$, and CO above the disk of Pluto. We find Pluto's brightness at Lyman $α$ to be $29.3\pm1.9$R, in good agreement with pre-encounter estimates. The detection of the N II multiplet at 1085Å marks the first direct detection of ions in Pluto's atmosphere. We do not detect any emissions from noble gasses and place a 3$σ$ upper limit of 0.14 R on the brightness of the Ar I 1048Å line. We compare pre-encounter model predictions and predictions from our own airglow model, based on atmospheric profiles derived from the solar occultation observed by New Horizons, to the observed brightness of Pluto's airglow. Although completely opaque at Lyman $α$, Pluto's atmosphere is optically thin at wavelengths longer than 1425Å. Consequently, a significant amount of solar FUV light reaches the surface, where it can participate in space weathering processes. From the brightness of sunlight reflected from Pluto, we find the surface has a reflectance factor (I/F) of 17% between 1400-1850Å. We also report the first detection of an C$_3$ hydrocarbon molecule, methylacetylene, in absorption, at a column density of ~5$\times10^{15}$ cm$^{-2}$, corresponding to a column-integrated mixing ratio of $1.6\times10^{-6}$.
