The architecture and formation of the Kepler-30 planetary system

Abstract

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 pair is near to the 2:1 mean motion resonance (MMR), and the outermost pair is close to higher order MMRs, such as 17:7 and 7:3. Our re-analysis of photometric data allows us to constrain, better than before, the orbital elements, planets' radii and masses, which are 9.2 ± 0.1, 536 ± 5, and 23.7 ± 1.3 Earth masses for Kepler-30b, Kepler-30c and Kepler-30d, respectively. The masses of the inner planets are determined within ∼ 1% uncertainty. We infer the internal structures of the Kepler-30 planets and their bulk densities in a wide range from (0.19 ± 0.01) g·cm −3 for Kepler-30d, (0.96 ± 0.15) g·cm −3 for Kepler-30b, to (1.71 ± 0.13) g·cm −3 for the Jovian planet Kepler-30c. We attempt to explain the origin of this unique planetary system and a deviation of the orbits from exact MMRs through the planetary migration scenario. We anticipate that the Jupiter-like planet plays an important role in determining the present dynamical state of this system. tems make it possible to further refine their orbital parameters and masses (e.g., Borsato et al. 2014;Barros et al. 2014).In this paper, we report on a new and up-to-date characterization of the Kepler-30 system composed of three planets. These planets have been validated by Fabrycky et al. (2012) on the basis of the very initial Q1-Q6 KEPLER data quarters ( 600 days) as well as by Tingley et al. (2011) on the basis of the first Q0-Q2 quarters.The early studies on this system were focused on the orbital-spin alignment and star-spots detection (Sanchis-Ojeda et al. 2012) or on differential rotation of the parent star (Lanza et al. 2014). Here, we take full advantage of the available light curves of Kepler-30, spanning Q1-Q17 quarters ( 1600 days) to constrain better the masses and orbital elements of the planets.We find the Kepler-30 system particularly interesting and unique in the KEPLER sample for several reasons. One of them is the huge TTV full-amplitude of the innermost planet of 2 days (48 hours), which is two times larger than the TTV fullamplitude of 1 day for the innermost planet in the Kepler-88 system (Nesvorný et al. 2013) dubbed as "the king of the transit c 2017 RAS

Identifying Exoplanets with Deep Learning: A Five-planet Resonant Chain around Kepler-80 and an Eighth Planet around Kepler-90

“…This system hosts two confirmed giant planets and a smaller confirmed super-Earth-sized planet called Kepler-30 b, which orbits with a period of 29.16days (Fabrycky et al 2012). All of these planets show TTVs, and Kepler-30 d shows extremely large TTVs with an amplitude of more than a day (Fabrycky et al 2012;Panichi et al 2017 Four of these new TCEs were predicted to be planets by our model with a probability of 0.9 or greater. We consider this to be a very confident prediction; among those objects in our test set to which our model assigned a planet probability greater than 0.9, 96% turned out to be correctly classified as planets.…”

Stability of exoplanetary systems retrieved from scalar time series

“…The stable chaos scenario suggested by Deck et al (2012) completely overlaps with the stickiness effect appearing at the border of regular domains (MMRs in celestial mechanics) in dynamical systems (Tsiganis et al 2000). In addition, Panichi et al (2018) also found that the system (Kepler-36) is very close to the border of the 7:6 MMR.…”

“…Thus one should handle the analysis with care. (Panichi et al 2018) showed that the integration time plays an important role in the stability investigation of this particular systems. Although, the initial conditions of the inner planet (Kepler-29b) are sitting well inside the regular domain of the (a, e) stability map for shorter time, it turns out that the center of the resonance becomes unstable for longer integration.…”

“…Since the gravitationally interacting, and therefore non-Keplerian, few-body dynamics can be very complex (Fabrycky 2010), it makes a great deal to investigate the stability of exoplanetary systems containing at least two planets (Rivera & Lissauer 2001;Armstrong et al 2015;Batygin et al 2015;Goździewski et al 2016;Panichi et al 2018). Dynamical modeling of multiple planetary systems requires precise initial conditions and system parameters in order to perform reliable n-body numerical integration.…”

A Transiting Warm Giant Planet around the Young Active Star TOI-201

“…TOI-201 b also joins the small but growing population of longer-period giant planets, helping to populate a still relatively sparse region of the radius-period diagram (Figure 10). On this diagram, it is located closest to Kepler-117 c (period 50.790391 ± 0.000014 days, radius 1.101 ± 0.035 R J , mass 1.84 ± 0.18 M J , eccentricity 0.0323 ± 0.0033; Bruno et al 2015) and Kepler-30 c (period 60.32503 ± 0.00010 days, radius 1.069 ± 0.025 R J , mass 1.686 ± 0.016 M J , eccentricity 0.0115 ± 0.0005; Panichi et al 2018) but is noticeably less massive and dense, and more eccentric, than both these planets. Given the relative youth of the TOI-201 system, with a stellar As noted in the introduction, the size and mass of warm Jupiters is determined by their metallicity.…”