在一个超热的巨大系外行星的夜边凝聚铁
David Ehrenreich1, Christophe Lovis2, Romain Allart2
1Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland. david.ehrenreich@unige.ch.
Nature
|March 13, 2020
概括
研究人员在超热系外行星WASP-76b中发现了不对称的大气特征, 这项发现有助于我们更好地了解极端系外行星的气候和化学成分.
科学领域:
- 外行星科学
- 大气化学
- 天体物理学
背景情况:
- 超热的巨大系外行星具有极端的温度 (> 2,000 K) 和高的阳光照射,使它们成为研究行星气候的理想选择.
- 大气模型预测白天无云, 原子物种占主导地位, 温度高于夜晚,
- 之前的观测证实了金属元素和温度对比, 但缺乏对系外行星表面的化学梯度的直接测量.
研究的目的:
- 探测和描述超热系外行星表面的化学梯度.
- 探究系外行星白天和夜晚大气中的化学差异.
- 为了识别不同大气成分的不对称吸收特征.
主要方法:
- 使用高分散光谱与一个大的光子收集区域,以光谱和暂时解决大气签名.
- 分析过境数据以识别特定元素的吸收信号.
- 测量了吸收信号的多普勒转移以推断风的模式和大气动态.
主要成果:
- 在WASP-76b的后肢上检测到与中性铁 (-11 ± 0.7公里/秒) 相关的蓝移吸收信号.
- 在夜边的早晨终结器附近没有观察到铁吸收信号.
- 这种不对称的铁形状是由行星旋转和日向夜风的组合所解释的.
结论:
- 证实在WASP-76b系外行星上存在化学梯度.
- 断定原子铁在从白天转移时必须在夜侧凝结.
- 提供了支持极端系外行星环境中的大气化学模型的观测证据.
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