论文标题
更新的参数和HD 97658B的新传输频谱
Updated Parameters and a New Transmission Spectrum of HD 97658b
论文作者
论文摘要
近年来,由于它们在银河系中的普遍性,与它们在太阳系中的缺失形成对比,人们对亚新次量大小的行星的表征越来越兴趣。 HD 97658是拥有此类行星的最亮恒星之一,我们通过将四个HST Transit,十二个Spitzer/IRAC Transits和该系统的八个最转移来呈现该行星的传播光谱。我们的传输频谱比以前的作品具有更高的信号与噪声比,结果表明,在以前关于该星球传输频谱的作品中,从波长1.1 1.1的传输深度略有增加可能是系统的。尽管如此,我们的大气建模结果并不是结论性,因为NO模型为我们的数据提供了极好的匹配。但是,我们发现具有较高的C/O比(C/O> 〜0.8)的大气和> 〜100倍太阳金属性的金属度受到青睐。我们结合了从所有新的Spitzer和大多数观测值的中期时间结合,并获得了P = 9.489295 +/- 0.000005 D的更新轨道周期,并在T_0 = 2456361.80690 +/- 0.00038(BJD)中提供最佳固定运输时间中心。在该系统中未发现过境时序变化。我们还提出了恒星旋转周期(34 +/- 2 D)和恒星活性周期(9.6年)的新测量值。最后,我们计算并对所有确认的行星的透射光谱指标进行计算和排名。我们发现,使用JWST可以很好地表征至少三分之一的小行星比1000 K的凉爽,而HD 97658B排名第五,这意味着它仍然是大气表征的高优先级目标。
Recent years have seen increasing interest in the characterization of sub-Neptune sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four HST transits, twelve Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has higher signal to noise ratio than that from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1 to 1.7 microns reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are not conclusive as no model provides an excellent match to our data. Nonetheless we find that atmospheres with high C/O ratios (C/O >~ 0.8) and metallicities of >~ 100x solar metallicity are favored. We combine the mid-transit times from all the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295 +/- 0.000005 d, with a best-fit transit time center at T_0 = 2456361.80690 +/- 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 +/- 2 d) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 and 4 R_Earth. We find that at least a third of small planets cooler than 1000 K can be well characterized using JWST, and of those, HD 97658b is ranked fifth, meaning it remains a high-priority target for atmospheric characterization.