Ground-based and space-borne observatories studying exoplanetary transits now and in the future will considerably increase the number of known exoplanets and the precision of the measured times of transit minima. Variations in the transit times can not only be used to infer the presence of additional planets, but might also provide opportunities for testing new physics in the places beyond the Solar system. In this work, we take deviation from the inverse-square law of gravity as an example, focus on the fifth-force-like Yukawa-type correction to the Newtonian gravitational force which parameterizes this deviation, investigate its effects on the secular transit timing variations and analyze their observability in exoplanetary systems. It is found that the most optimistic values of Yukawa-type secular transit timing variations are at the level of $\sim 0.1$ seconds per year. Those values unfortunately appear only in rarely unique cases and, most importantly, they are still at least two orders of magnitude below the current capabilities of observations. Such a deviation from the inverse-square law of gravity is likely too small to detect for the foreseeable future. Meanwhile, systematic uncertainties, such as the presence of additional and unknown planets, will likely be exceptionally difficult to remove from a signal that should be seen.
ExoEcho: Exoplanet Ephemerides Change Observations. III. A JWST Survey for Transit Timing Variations of 37 Exoplanets
School of Physics and Astronomy, Sun Yat-sen University(中山大学物理学院);CSST Science Center for the Guangdong-Hong Kong-Macau Great Bay Area, Sun Yat-sen University(中山大学粤港澳大湾区空间望远镜科学中心)
Considering the importance of investigating the transit timing variations (TTVs) of transiting exoplanets, we present a follow-up study of HAT-P-12b. We include six new light curves observed between 2011 and 2015 from three different observatories, in association with 25 light curves taken from the published literature. The sample of the data used, thus covers a time span of about 10.2 years with a large coverage of epochs (1160) for the transiting events of the exoplanet HAT-P-12b. The light curves are used to determine the orbital parameters and conduct an investigation of possible transit t…
Motivated by the unsettled conclusion on whether there are any transit timing variations (TTVs) for the exoplanet Qatar-1b, 10 new transit light curves are presented and the TTV analysis with a baseline of 1400 epochs are performed. Because the linear model provides a good fitting with reduced chi-square = 2.59 and the false-alarm probabilities of possible TTV frequencies are as large as 35 %, our results are consistent with a null-TTV model. Nevertheless, a new ephemeris with the reference time T_0 = 2455647.63360\pm 0.00008 (BJD) and the period P= 1.4200236\pm 0.0000001 (day) is obtained. In…
From previous ground-based observations, the hot Jupiter exoplanet XO-6b was reported to exhibit apparently periodic transit timing variations (TTVs), with a semi-amplitude of 14 minutes and a period of about 450 days. These variations were interpreted as being due to a resonant perturbation between XO-6b and a hitherto unknown low-mass planet orbiting the same star. To understand this enigmatic planetary system better, we analysed three sectors of data, spanning over seven months, from the Transiting Exoplanet Survey Satellite (TESS), which produces high-quality light curves that are well sui…
We consider the issue of excessive TTV noise observed for the exoplanet HD 189733 b. Trying to explain it through the host star photospheric activity, we model the stellar surface brightness as a random field, then characterize statistical properties of the resulting transit signal perturbation and compute individual corrections to transit timings uncertainties. We find that possible effect of the photospheric brightness field can explain only a minor portion ($\sim 10$ s) of the observed ($\sim 70$ s) TTV excess of HD 189733, suggesting that the rest should be attributed to other sources. Reg…
5 Years of Defocused Observations of Exoplanet Transits with T100: Timing Perspective
我们已经进行了五年多的计划,利用1米土耳其望远镜T100(Bainturk et al. 2014,2015)观察选定系外行星的凌日,通过利用成熟的散焦技术(Southworth et al. 2009)来实现高光度精度。在这篇文章中,我们回顾了我们的观测计划在时间的角度来看。散焦技术背后的基本思想是在观测亮星时使探测器保持较长的持续时间,否则在很短的积分时间内就可以观测到。然后光子噪声的影响被减弱,这在短节奏观测中占主导地位。较长时间的暴露也有助于减少大气闪烁的噪声贡献。通过在检测器上的更大区域上积分,也减轻了不完美跟踪和平场的噪声贡献。虽然在给定的时间内可以获得较少的图像,我们认为,由于更好的光度精度的定时精度提高。该贡献得到了TÜBÜV TAK-3001项目116 F350的支持。
TraMoS project III: Improved physical parameters, timing analysis, and star-spot modelling of the WASP-4b exoplanet system from 38 transit observations
We study the transit timings of 10 exoplanets in order to investigate potential Transit Timing Variations (TTVs) in them. We model their available ground-based light curves, some presented here and others taken from the literature, and homogeneously measure the mid-transit times. We statistically compare our results with published values and find that the measurement errors agree. However, in terms of recovering the possible frequencies, homogeneous sets can be found to be more useful, of which no statistically relevant example has been found for the planets in our study. We corrected the ephe…
SOPHIE velocimetry of Kepler transit candidates: X KOI-142c: first radial velocity confirmation of a non-transiting exoplanet discovered by transit timing
系外行星KOI-142 b(开普勒-88 b)显示出半振幅为$\sim 12\,$小时的凌日时间变化(TTV),赢得了“凌日变化之王”的绰号。在开普勒的数据中只发现了行星b的凌日,其轨道周期为$\sim 10.92\,$天,半径为$\sim 0.36$ R $_{\mathrm{Jup}}$。Nesvorny等人(2013年)分析了KOI-142 b的TTV和凌日持续时间变化(TDV),他们发现了一个独特的伴星扰动行星的解决方案。作者预测了一颗外层非凌日伴星KOI-142 c,质量为$0.626\pm 0.03$ M $_{\mathrm{Jup}}$,周期为$22.3397^{+0.0021}_{-0.0018}\,$天,因此接近于与内层凌日行星的2:1平均运动共振。我们报告独立确认KOI-142 c使用径向速度观测与SOPHIE光谱仪在上普罗旺斯天文台。我们得到了一个轨道周期$22.10 \pm 0.25\,$天和一个最小行星质量$0.76^{+0.32}_{0.16}\,$ M $_{\mathrm{Jup}}$,都与以前的过境时间分析的预测吻合得很好。因此,这是第一次确认一颗非凌日行星的径向速度,发现了凌日时间的变化,为TTV技术提供了独立的验证。
A Deep Learning Framework for TTV Characterization: A Case Study of the Kepler-88 System
School of Earth and Atmospheric Sciences, Georgia Institute of Technology(佐治亚理工学院地球与大气科学学院);School of Mathematics, Georgia Institute of Technology(佐治亚理工学院数学学院);Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology(佐治亚理工学院物理学院相对论天体物理中心);Machine Learning Center, Georgia Institute of Technology(佐治亚理工学院机器学习中心)
In this study, the transit observations of HAT-P-16b and TrES-3b exoplanets were carried out at ÇÜ UZAYMER Observatory with a 50 cm Ritchey Chretien type telescope. By analyzing the light curves of both exoplanets, system parameters have been obtained with acceptable models. Some of these parameters for HAT-P-16 systems were found to be: M$_{P}$=4.172$\pm$0.163 M$_{J}$, R$_{P}$=1.309$\pm$0.111 R$_{J}$, a/R$_{*}$=7.1922$\pm$0.0017 and b=0.1003$\pm$0.1533 which are consistent with the values given in \cite{2010ApJ...720.1118B}. Also, for the TrES-3 system, the same parameters were calculated as …
Transit timing variations in eccentric hierarchical triple exoplanetary systems. I. Perturbations on the time-scale of the orbital period of the perturber
Transiting Exoplanet Monitoring Project (TEMP). IV. Refined System Parameters, Transit Timing Variations and Orbital Stability of the Transiting Planetary System HAT-P-25
The Efficiency of Geometric Samplers for Exoplanet Transit Timing Variation Models
凌日时变(TTV)是确定多行星系统中凌日行星质量和轨道的重要工具。如果知道相互作用的行星的轨道结构和行星-恒星质量比,TTV可以很容易地建模,但这样的模型是高度非线性的,很难反演。马尔可夫链蒙特卡罗(MCMC)方法通常用于探索模型参数的后验分布,但是,由于参数之间的高度相关性,非线性和后验中潜在的多模态,许多采样器的效率非常低。因此,我们评估了几个MCMC采样器,使用不同程度的几何信息的目标分布的性能。我们从多个模型生成合成数据集,包括TTVFaster模型和一个简单的正弦模型,并测试各种MCMC采样器的效率。我们发现,采样效率可以大大提高所有模型的采样从一个参数空间转换使用的协方差估计和目标分布的手段。没有一个采样器对所有数据集都表现最好,但有几个采样器,如差分进化蒙特卡罗和几何自适应蒙特卡罗,具有一致的高效性能。对于具有近高斯后验的数据集,具有2或3个蛙跳步骤的Hamilton Monte Carlo采样器获得了最高的效率。基于每次有效样本量的差异,我们表明,正确选择采样器可以提高采样效率的几个数量级。
Departure from the constant-period ephemeris for the transiting exoplanet WASP-12 b
由于轨道运动的角动量转移到恒星的自旋上,大多数热彗星都被认为是朝着它们的宿主恒星螺旋运动的。它们的轨道也可以由于行星-恒星相互作用而进动。计算表明,这两种影响都可以检测到非常热的系外行星WASP-12 b使用精确的过境时间超过10年的时间跨度的方法。从2012年11月到2016年2月,我们获得了WASP-12 b 29次凌日的新的精确光变曲线。新的中星时,与文献一起,被用来改进凌历表和分析定时残差。我们发现,WASP-12 b的渡越时间不遵循线性星历与5西格玛的置信水平。它们可以用二次星历来近似,其轨道周期的变化率为-2.56 +/- 0.40 x 10^{-2} s/yr。主恒星的潮汐质量参数被发现等于2.5 x 10^5,这与类太阳恒星的理论预测相当。我们还考虑了一个模型,其中所观察到的定时残差被解释为拱点进动的结果。然而,我们发现,这个模型在统计上比轨道衰变的可能性小。
HIP 41378 f is a temperate $9.2\pm0.1 R_{\oplus}$ planet with period of 542.08 days and an extremely low density of $0.09\pm0.02$ g cm$^{-3}$. It transits the bright star HIP 41378 (V=8.93), making it an exciting target for atmospheric characterization including transmission spectroscopy. HIP 41378 was monitored photometrically between the dates of 2019 November 19 and November 28. We detected a transit of HIP 41378 f with NGTS, just the third transit ever detected for this planet, which confirms the orbital period. This is also the first ground-based detection of a transit of HIP 41378 f. Add…
The WASP-148 planetary system has a rare architecture with a transiting Saturn-mass planet on a tight orbit which is accompanied by a slightly more massive planet on a nearby outer orbit. Using new space-born photometry and ground-based follow-up transit observations and data available in literature, we performed modeling that accounts for gravitational interactions between both planets. Thanks to the new transit timing data for planet b, uncertainties of orbital periods and eccentricities for both planets were reduced relative to previously published values by a factor of 3-4. Variation in tr…