Red Optical Planet Survey: a new search for habitable earths in the southern sky Low-mass M dwarf planets with ROPS
Red Optical Planet Survey: a new search for habitable earths in the southern sky Low-mass M dwarf planets with ROPS
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红色光学行星巡天：在南部天空寻找宜居地球的新研究 具有 ROPS 的低质量 M 矮行星
DOI：
10.1111/j.1365-2966.2012.21236.x
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发表时间：
2012
影响因子：
4.8
通讯作者：
Barnes J
中科院分区：
文献类型：
--
作者：
Barnes J
我们介绍了我们的红色光学行星调查(ROPS)在其宜居带(HZ)中搜索围绕晚型矮星(M5.5V-M9V)运行的低质量行星的第一个结果。我们在拉斯坎帕纳斯天文台6.5米麦哲伦粘土望远镜上用迈克光谱仪的红色臂(0.5-0.9微米)进行的观测表明，92%的通量位于0.7微米以上。我们使用一种新的方法，本质上是同时测定径向速度的碘法和塔尔法的混合体。我们用最小二乘反褶积得到每一个光谱的一条高S/N比恒星线，并与我们用同样方法得到的同时观测到的大地线轮廓进行互相关。利用0.62-0.90微米区域，我们已经实现了R.M.S。对于一颗光谱为S/N~160的M5.5V光谱型恒星，在5分钟时间尺度上的精度为10m/S。根据M8V谱型，建议S/N=25时的精度为~30m/S，但还需要更多的观测。对我们在径向速度点上的误差和散布的评估暗示了恒星径向速度变化的存在。在我们的7颗恒星样本中，有2颗显示了互相关不确定度为6西格玛和10西格玛的径向速度信号。如果信号是行星起源的，我们的发现与海王星质量行星的估计是一致的，海王星质量行星预测早期M矮星的频率为13%-27%。我们目前的分析表明，我们可以获得相当于6M_Earth行星在宜居带轨道上产生的幅度的灵敏度。基于模拟，我们估计将在一个新的恒星质量体系中探测到<；10颗M_地球宜居带行星，观测<；=20个纪元。
We present the first results from our Red Optical Planet Survey (ROPS) to search for low mass planets orbiting late type dwarfs (M5.5V - M9V) in their habitable zones (HZ). Our observations, with the red arm of the MIKE spectrograph (0.5 - 0.9 microns) at the 6.5 m Magellan Clay telescope at Las Campanas Observatory indicate that >= 92 per cent of the flux lies beyond 0.7 microns. We use a novel approach that is essentially a hybrid of the simultaneous iodine and ThAr methods for determining precision radial velocities. We apply least squares deconvolution to obtain a single high S/N ratio stellar line for each spectrum and cross correlate against the simultaneously observed telluric line profile, which we derive in the same way. Utilising the 0.62 - 0.90 micron region, we have achieved an r.m.s. precision of 10 m/s for an M5.5V spectral type star with spectral S/N ~160 on 5 minute timescales. By M8V spectral type, a precision of ~30 m/s at S/N = 25 is suggested, although more observations are needed. An assessment of our errors and scatter in the radial velocity points hints at the presence of stellar radial velocity variations. Of our sample of 7 stars, 2 show radial velocity signals at 6-sigma and 10-sigma of the cross correlation uncertainties. If the signals are planetary in origin, our findings are consistent with estimates of Neptune mass planets that predict a frequency of 13 - 27 per cent for early M dwarfs.Our current analysis indicates the we can achieve a sensitivity that is equivalent to the amplitude induced by a 6 M_Earth planet orbiting in the habitable zone. Based on simulations, we estimate that <10 M_Earth habitable zone planets will be detected in a new stellar mass regime, with <=20 epochs of observations.