We validate the planetary origin of the KOI-1599 transit time variations (TTVs) with statistical and dynamical tests. We re-analysed KEPLER Q1-Q17 light-curves of the star, and we independently derived the TTVs. They appear as strongly anti-correlated, suggestive of two mutually interacting planets. We found similar radii of the candidates, $1.9 \pm 0.2\, \mbox{R}_{\oplus}$ for the inner KOI-1599.02, and $1.9 \pm 0.3 \, \mbox{R}_{\oplus}$ for the outer KOI-1599.01. The standard MCMC TTV analysis constrains the planet masses safely below the dynamical instability limit of $\simeq 3\, \mbox{M}_{\mbox{Jup}} $. The best-fitting MCMC model yields $(9.0\pm 0.3)\, \mbox{R}_{\oplus}$, and $(4.6\pm0.3),\ \mbox{R}_{\oplus}$, for the inner and the outer planet, respectively. The planets are trapped in 3:2 mean motion resonance (MMR) with anti-aligned apsides ($Δ\varpi = 180^{\circ}$) at low-eccentric ($e\simeq 0.01)$ orbits. However, we found that the TTV mass determination depends on eccentricity priors with the dispersion in the (0.01,0.05) range. They permit a second family of TTV models with smaller masses of $\simeq 7\,\mbox{R}_{\oplus}$, and $\simeq 3.6\,\mbox{R}_{\oplus}$, respectively, exhibiting two modes of $Δ\varpi = 0^{\circ},180^{\circ}$ librations. The 3:2 MMR is dynamically robust and persists for both modes. In order to resolve the mass duality, we re-analysed the TTV data with a quasi-analytic model of resonant TTV signals. This model favours the smaller masses. We also reproduced this model with simulating the migration capture of the system into the 3:2 MMR.
Secure TTV Mass Measurements: Ten Kepler Exoplanets between 3 and 8 Earth Masses with Diverse Densities and Incident Fluxes
我们推断动力学质量在八个多行星系统使用开普勒的完整数据集，包括短节奏的数据在可用的过境时间。在我们推断出的18个动力学质量中，有10个通过了多次鲁棒性测试。这些都是在系统中;开普勒-26（KOI-250），开普勒-29（KOI-738），开普勒-60（KOI-2086），开普勒-105（KOI-115）和开普勒-307（KOI-1576）。开普勒-105 c的密度与地球的成分一致。从其他行星上探测到了强烈的TTV信号，但它们的推断质量对异常值敏感，或者无法用独立测量的过境时间找到一致的解决方案，包括开普勒-49（KOI-248），开普勒-57（KOI-1270），开普勒-105（KOI-115）和开普勒-177（KOI-523）的行星。开普勒-177 c的质量上限很大，这意味着它的密度极低，约为0.1 g cm $^{-3}$。在大多数情况下，由于TTV反演中的简并性，个体轨道偏心率约束不佳。对于我们样本中的五个行星对，强的长期相互作用意味着在很大范围内可能的偏心率上有中等到高的拱点对齐可能性。我们还找到了已知的三颗行星在开普勒-60轨道上的拉普拉斯共振链的解决方案。然而，非振动的解决方案也符合过境定时数据。对于六个系统，我们计算出比以前已知的更精确的恒星参数，使我们有强大的质量测量行星密度有用的约束。将这些系外行星的质量半径图，我们发现一个广泛的密度范围内观察到的次海王星质量的行…
With the use of numerical models, we investigate whether Mean Motion Resonances (MMR) with nearby moons to the J1407b ring system were the cause of the observed 0.0267AU wide gap located at 0.4AU. Only one location of a moon at 0.63AU (corresponding to a 2:1 MMR) was found to form a gap at 0.4AU over short time periods of less than 100yr. However, the proximity of a low mass moon (0.08 Earth masses) caused significant scattering of the outer ring edge at 0.6AU, along with the formation of an additional gap at the 3:2 MMR (0.485 AU), which is not consistent with observations. Further models wit…
Context. Findings by the Helios and STEREO mission have indicated the presence of a resonant circumsolar ring of dust associated with Venus. Attempts to model this phenomenon as an analogue to the resonant ring of Earth - as a result of migrating dust trapped in external mean-motion resonances (MMRs) - have so far been unable to reproduce the observed dust feature. Other theories of origin have recently been put forward. However, the reason for the low trapping efficiency of Venus's external MMRs remains unclear. Aims. Here we look into the nature of the dust trapping resonant phenomena that a…
Inferring planetary parameters from transit timing variations is challenging for small exoplanets because their transits may be so weak that determination of individual transit timing is difficult or impossible. We implement a useful combination of tools which together provide a numerically fast global photodynamical model. This is used to fit the TTV-bearing light-curve, in order to constrain the masses of transiting exoplanets in low eccentricity, multi-planet systems - and small planets in particular. We present inferred dynamical masses and orbital eccentricities in four multi-planet syste…
Stellar positions and velocities from Gaia are yielding a new view of open cluster dispersal. Here we present an analysis of a group of stars spanning Cepheus to Hercules, hereafter the Cep-Her complex. The group includes four Kepler Objects of Interest: Kepler-1643 b ($2.32 \pm 0.13$ Earth-radii, 5.3 day orbital period), KOI-7368 b ($2.22 \pm 0.12$ Earth-radii, 6.8 days), KOI-7913 Ab ($2.34 \pm 0.18$ Earth-radii, 24.2 days), and Kepler-1627 Ab ($3.85 \pm 0.11$ Earth-radii, 7.2 days). The latter Neptune-sized planet is in part of the Cep-Her complex called the $δ$ Lyr cluster (Bouma et al. 202…
Habitable Zones for Earth-mass Planets in Multiple Planetary Systems
本文通过数值模拟研究了多行星系中地球质量行星的宜居带和动力学结构。例如，在HD 69830系统中，我们广泛地探索了三个海王星质量的同伴的行星配置，其中一个大质量的类地行星居住在0.07 AU $\leq a \leq$ 1.20 AU，以研究该系统中的小行星结构。我们强调，有至少$10^5$年的稳定区的低质量类地行星位于0.3和0.5 AU之间，和0.8和1.2 AU的最终偏心率为$e < 0.20$。此外，我们还发现小行星带的积累或耗尽也受到外行星轨道共振的影响，例如，与行星C的2：1和3：2平均运动共振（MMRs）以及与行星D的5：2和1：2 MMRs的小行星间隙。在动力学意义上，潜在类地行星或HZ存在的合适候选区域为0.35 AU $< a < $ 0.50 AU，以及0.80 AU $< a < $ 1.00 AU，这对于该系统中可能存在的小行星结构是有意义的。
Université de Genève（日内瓦大学）；Monash University（莫纳什大学）；Disaitek；Universität Bern（伯尔尼大学）
Transit Timing Variations (TTVs) can provide useful information for systems observed by transit, by putting constraints on the masses and eccentricities of the observed planets, or even constrain the existence of non-transiting companions. However, TTVs can also prevent the detection of small planets in transit surveys, or bias the recovered planetary and transit parameters. Here we show that Kepler-1972 c, initially the "not transit-like" false positive KOI-3184.02, is an Earth-sized planet whose orbit is perturbed by Kepler-1972 b (initially KOI-3184.01). The pair is locked in a 3:2 Mean-mot…
Planetary formation theories and, more specifically, migration models predict that planets can be captured in mean-motion resonances (MMRs) during the disc phase. The distribution of period ratios between adjacent planets shows an accumulation in the vicinity of the resonance, which is not centred on the nominal resonance but instead presents an offset slightly exterior to it. Here we extend on previous works by thoroughly exploring the effect of different disc and planet parameters on the resonance offset during the disc migration phase. The dynamical study is carried out for several first-or…
We visually analyzed the Transit Timing Variation (TTV) data of 5930 Kepler Objects of Interest (KOIs) homogeneously. Using data from Rowe et al. 2014 and Holczer et al. 2016, we investigated TTVs for KOIs in Kepler's Data Release 24 catalog. Using TTV plots, periodograms, and folded quadratic sinusoid fits, we visually rated each KOI's TTV data in five categories. Our ratings emphasize the hundreds of planets with TTVs that are weaker than the 200 or so that have been studied in detail. Our findings are consistent with statistical methods for identifying strong TTVs (Holczer et al. 2016), tho…
All 4 giant planets in the Solar System host systems of multiple moons, whereas the terrestrial planets only host up to 2 moons. The Earth can capture small asteroids as temporary satellites, which begs the question as to how many moons could stably orbit the Earth, or an Earth-mass exoplanet. We perform a series of N-body simulations of closely-spaced equal mass moons in nested orbits around an Earth-mass planet orbiting a Sun-like star. The innermost moon begins near the host planets Roche radius, and the system is packed until the outermost moon begins near the stability limit for single mo…
We study the orbital architecture, physical characteristics of planets, formation and long-term evolution of the Kepler-30 planetary system, detected and announced in 2012 by the KEPLER team. We show that the Kepler-30 system belongs to a particular class of very compact and quasi-resonant, yet long-term stable planetary systems. We re-analyse the light curves of the host star spanning Q1-Q17 quarters of the KEPLER mission. A huge variability of the Transit Timing Variations (TTV) exceeding 2 days is induced by a massive Jovian planet located between two Neptune-like companions. The innermost …
We study the spin evolution of close-in planets in multi-body systems and present a very general formulation of the spin-orbit problem. This includes a simple way to probe the spin dynamics from the orbital perturbations, a new method for computing forced librations and tidal deformation, and general expressions for the tidal torque and capture probabilities in resonance. We show that planet-planet perturbations can drive the spin of Earth-size planets into asynchronous or chaotic states, even for nearly circular orbits. We apply our results to Mercury and to the KOI-1599 system of two super-E…
Discovery of Small Ultra-short-period Planets Orbiting KG Dwarfs in Kepler Survey Using GPU Phase Folding and Deep Learning Detection System
Science Talent Training Center（科学人才培养中心）；Stanford University（斯坦福大学）；Shanghai Astronomical Observatory（上海天文台）；Princeton University（普林斯顿大学）；University of Geneva（日内瓦大学）；University of Chinese Academy of Sciences（中国科学院大学）
Planetary systems with multiple giant planets provide important opportunities to study planetary formation and evolution. The HD 45364 system hosts two giant planets that reside within the Habitable Zone (HZ) of their host star and was the first system discovered with a 3:2 mean motion resonance (MMR). Several competing migration theories with different predictions have previously provided explanations regarding the observed resonance through dynamical simulations that utilized limited data. Here, over ten years since the original discovery, we revisit the system with a substantially increased…
Impact of Cold Jupiter Scattering on the Mean-Motion Resonance of Inner Small Planets
Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交大李政道研究所）；Center for Astrophysics and Planetary Science, Department of Astronomy, Cornell University（康奈尔大学天文学系天体物理与行星科学中心）
Two photometric follow-up transit (primary eclipse) observations on WASP-43 b and four observations on TrES-3 b are performed using the Xuyi Near-Earth Object Survey Telescope. After differential photometry and light curve analysis, the physical parameters of the two systems are obtained and are in good match with the literature. Combining with transit data from a lot of literature, the residuals ($O-C$) of transit observations of both systems are fitted with the linear and quadratic functions. With the linear fitting, the periods and transit timing variations (TTVs) of the planets are obtaine…
The Sun-like star Kepler-160 (KOI-456) has been known to host two transiting planets, Kepler-160 b and c, of which planet c shows substantial transit-timing variations (TTVs). We used the archival Kepler photometry of Kepler-160 to search for additional transiting planets using a combination of our Wotan detrending algorithm and our transit least-squares (TLS) detection algorithm. We also used the Mercury N-body gravity code to study the orbital dynamics of the system. First, we recovered the known transit series of planets Kepler-160 b and c. Then we found a new transiting candidate with a ra…
