用HST/STISIS对Io大气层进行远紫外线成像光谱
F L Roesler1, H W Moos, R J Oliversen
1Physics Department, University of Wisconsin, 1150 University Avenue, Madison, WI 53706, USA.
Science (New York, N.Y.)
|January 15, 1999
概括
远紫外线成像揭示了有关木星卫星Io的极光辐射的新细节. 氧气和硫的排放显示出与木星磁场相关的明显模式,而气排放表现出独特的行为.
科学领域:
- 行星科学 行星科学
- 空间物理 空间物理
- 天体物理学 天体物理学
背景情况:
- 木星的火山活动月亮Io拥有薄弱的大气层,沉浸在木星强烈的磁层中.
- 之前的观测已经检测到Io的辐射,但远紫外光谱的详细空间和时间变化并未得到充分理解.
研究的目的:
- 调查 Io. 远紫外线辐射的空间分布和时间变化.
- 识别和描述以前未被检测到的排放,如Lyman-alpha,并将其与已知的氧气和硫排放进行比较.
主要方法:
- 利用哈勃太空望远镜成像光谱仪 (STIS) 来获得Io的高分辨率远紫外光谱图像.
- 分析了波长范围为1250至1500安格斯特姆的辐射,重点关注O I,SI和H莱曼-α线.
主要成果:
- 检测到OI和SI辐射的明亮的赤道点,随着木星的磁场方向的变化而变化.
- 观测到的肢体在面对木星磁赤道的半球上发出更明亮的光,散射辐射延伸到~20 Io半径.
- 观察到OI和SI特征的亮度增加了50%左右,与地面观测增加的电离子[OI]6300安格斯特罗姆发射的时间相吻合.
- 识别了H Lyman-alpha辐射作为具有明显形态和时间变化的小极点.
结论:
- 的极光辐射表现出复杂的空间结构,直接受到木星磁层的影响.
- 观察到的亮度增加表明磁层条件与Io的大气/发射过程之间存在联系.
- 莱曼-α排放与氧和硫排放有着不同的现象,需要进一步研究.
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