Using the Sun to estimate Earth-like planets detection capabilities II. Impact of plages
Using the Sun to estimate Earth-like planets detection capabilities II. Impact of plages
复制标题
利用太阳估算类地行星探测能力二．
DOI：
10.1051/0004-6361/200913551
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发表时间：
2010
影响因子：
2.5
通讯作者：
A. Lagrange
中科院分区：
文献类型：
--
作者：
N. Meunier;M. Desort;A. Lagrange
黑子和斑块产生的恒星活动影响径向速度(RV)特征。因为即使是低活动度的恒星也会产生这样的信号，因此确定它如何影响我们探测微小行星信号的能力是至关重要的，例如由宜居带(HZ)中地球质量的行星产生的信号。在最近的一篇论文中，我们研究了类太阳黑子的影响。我们在这里的目的是调查菌斑的额外影响。我们使用一个太阳周期中的黑子和斑块属性来推导出当太阳侧面被看到时所观察到的RV。RV信号来自斑点和斑块的光度贡献以及斑块对流蓝移的衰减。我们将RV信号与HZ中一个地球质量的行星产生的信号进行了比较。我们发现，光斑和斑块对RV信号的光度贡献部分地相互平衡，因此剩余信号与光斑信号相当。然而，由于对流蓝移衰减引起的斑块贡献占了总信号的大部分，在太阳周期内的幅度约为8-10m/S，这一贡献与长期内的Ca指数有很强的相关性，这可能是区分恒星活动和行星的一种方法。提供非常好的时间采样和信噪比，斑块和斑点的光度贡献不应阻碍对HZ中地球质量行星的探测。然而，对流的贡献使这种直接探测变得不可能，除非它的影响可以通过仍然需要找到的方法来修正。我们证明，如果灵敏度足够好，例如，通过使用活动指示器，就有可能识别对流贡献。
Stellar activity produced by spots and plages affects the radial velocity (RV) signatures. Because even low activity stars would produce such a signal, it is crucial to determine how it influences our ability to detect small planetary signals such as those produced by Earth-mass planets in the habitable zone (HZ). In a recent paper, we investigated the impact of sunlike spots. We aim here to investigate the additional impact of plages. We used the spot and plage properties over a solar cycle to derive the RV that would be observed if the Sun was seen edge-on. The RV signal comes from the photometric contribution of spots and plages and from the attenuation of the convective blueshift in plages. We compared the RV signal with the signal that would be produced by an Earth-mass planet in the HZ. We find that the photometric contributions of spots and plages to the RV signal partially balance each other out, so that the residual signal is comparable to the spot signal. However, the plage contribution due to the convective blueshift attenuation dominates the total signal, with an amplitude over the solar cycle of about 8-10 m/s. This contribution is very strongly correlated with the Ca index on the long term, which may be a way to distinguish between stellar activity and a planet. Providing a very good temporal sampling and signal-to-noise ratio, the photometric contribution of plages and spots should not prevent detection of Earth-mass planets in the HZ. However, the convection contribution makes such a direct detection impossible, unless its effect can be corrected for by methods that still need to be found. We show that it is possible to identify the convection contribution if the sensitivity is good enough, for example, by using activity indicators.