Spectral determination of the colour and vertical structure of dark spots in Neptune's atmosphere
Spectral determination of the colour and vertical structure of dark spots in Neptune's atmosphere
复制标题
海王星大气中黑斑颜色和垂直结构的光谱测定
DOI：
10.1038/s41550-023-02047-0
复制
发表时间：
2023
期刊：
影响因子：
14.1
通讯作者：
Irwin P
中科院分区：
文献类型：
--
作者：
Irwin P
以前对海王星大气中的暗涡旋的观测，如旅行者2号的S大暗斑(1989年)，只在几个宽波长通道上进行了观测，阻碍了确定这些涡旋的压强水平和变暗过程的努力。我们分析了哈勃太空望远镜确定为NDS-2018的海王星上一个暗斑的光谱观测；光谱观测是由智利甚大望远镜的多单元光谱探测器(MUSE)于2019年进行的。缪斯的475-933 nm中分辨率反射光谱表明，暗斑是由~5 巴深气溶胶层的短波(<；700 nm)变暗引起的，我们认为它是H_2S冷凝层。在NDS-2018年的边缘也可以看到一个名为dbs-2019的深亮点，其光谱特征与相同的5 条层在更长的波长(>；700 nm)下变亮一致。这一明亮的特征比之前研究的暗斑伴生云要深得多，可能与产生和维持这些黑点的环流有关。
Previous observations of dark vortices in Neptune’s atmosphere, such as Voyager 2’s Great Dark Spot (1989), have been made in only a few broad-wavelength channels, hampering efforts to determine these vortices’ pressure levels and darkening processes. We analyse spectroscopic observations of a dark spot on Neptune identified by the Hubble Space Telescope as NDS-2018; the spectral observations were made in 2019 by the Multi Unit Spectroscopic Explorer (MUSE) of the Very Large Telescope (Chile). The MUSE medium-resolution 475–933 nm reflection spectra allow us to show that dark spots are caused by darkening at short wavelengths (<700 nm) of a deep ~5 bar aerosol layer, which we suggest is the H2S condensation layer. A deep bright spot, named DBS-2019, is also visible on the edge of NDS-2018, with a spectral signature consistent with a brightening of the same 5 bar layer at longer wavelengths (>700 nm). This bright feature is much deeper than previously studied dark-spot companion clouds and may be connected with the circulation that generates and sustains such spots.