Kepler-411: a four-planet system with an active host star

Sun, Lanlan; Ioannidis, P.; Gu, Shuhang; Schmitt, J. H. M. M.; Wang, Xiaobin; Kouwenhoven, M. B. N.

doi:10.1051/0004-6361/201834275

“…We conclude with announcing the detection of a fifth planet positioned in near 3:2 resonance to Kepler-82c. After the recent discovery of Kepler-411e (Sun et al 2019), Kepler-82f is the second non-transiting planet detected via the TTVs of two other planets. Determining the correct system architecture is important for modelling the right planet compositions.…”

Section: Discussionmentioning

confidence: 99%

Kepler Object of Interest Network

Freudenthal

¹

,

Essen

²

,

Agol

³

et al. 2019

A&A

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Context. The Kepler Object of Interest Network (KOINet) is a multi-site network of telescopes around the globe organised for follow-up observations of transiting planet candidate Kepler objects of interest with large transit timing variations (TTVs). The main goal of KOINet is the completion of their TTV curves as the Kepler telescope stopped observing the original Kepler field in 2013. Aims. We ensure a comprehensive characterisation of the investigated systems by analysing Kepler data combined with new ground-based transit data using a photodynamical model. This method is applied to the Kepler-82 system leading to its first dynamic analysis. Methods. In order to provide a coherent description of all observations simultaneously, we combine the numerical integration of the gravitational dynamics of a system over the time span of observations with a transit light curve model. To explore the model parameter space, this photodynamical model is coupled with a Markov chain Monte Carlo algorithm. Results. The Kepler-82b/c system shows sinusoidal TTVs due to their near 2:1 resonance dynamical interaction. An additional chopping effect in the TTVs of Kepler-82c hints to a further planet near the 3:2 or 3:1 resonance. We photodynamically analysed Kepler long- and short-cadence data and three new transit observations obtained by KOINet between 2014 and 2018. Our result reveals a non-transiting outer planet with a mass of mf = 20.9 ± 1.0 M⊕ near the 3:2 resonance to the outermost known planet, Kepler-82c. Furthermore, we determined the densities of planets b and c to the significantly more precise values ρb = 0.98−0.14+0.10 g cm−3 and ρc = 0.494−0.077+0.066 g cm−3.

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“…The third planet we consider here, Kepler-411 d, is about 10 times older than AU Mic b. The age of the system is estimated to be 212 ± 31 Myr (Sun et al 2019), which is too old for applying the same approach as for two other planets. Based on the conclusions made in Owen (2020), we expect the post-formation luminosity to be dissipated at this point in time.…”

Section: Initial Conditions: Post-formation Luminosity Of Young Planetsmentioning

confidence: 99%

How does the mass and activity history of the host star affect the population of low-mass planets?

Kubyshkina,

Vidotto

2021

Preprint

0

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The evolution of the atmospheres of low and intermediate-mass planets is strongly connected to the physical properties of their host stars. The types and the past activities of planet-hosting stars can, therefore, affect the overall planetary population. In this paper, we perform a comparative study of sub-Neptune-like planets orbiting stars of different masses and different evolutionary histories. We discuss the general patterns of the evolved population as a function of parameters and environments of planets. As a model of the atmospheric evolution, we employ the own framework combining planetary evolution in MESA with the realistic prescription of the escape of hydrogen-dominated atmospheres. We find that the final populations look qualitatively similar in terms of the atmospheres survival around different stars, but qualitatively different, with this difference accentuated for planets orbiting more massive stars. We show that a planet has larger chances of keeping its primordial atmosphere in the habitable zone of a solar mass star compared to M or K dwarfs and if it starts the evolution having a relatively compact envelope. We also address the problem of the uncertain initial temperatures (luminosities) of planets and show that this issue is only of particular importance for planets exposed to extreme atmospheric mass-losses.

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“…With S p ≈ 220 S ⊕ , it seems that photoevaporation could also have a hand in the density of Kepler-411 b. However, the system is relatively young, with a gyrochronological age of 212 ± 31 Myr (Sun et al 2019). Using Equation (15) from Lecavelier Des Etangs (2007), we find that with a = 0.038 au, Kepler-411 b would only lose 0.01 M ⊕ due to extreme ultraviolet (EUV) radiation from its K2V host over the system's gyrochronological age.…”

Section: Superdense Sub-neptune Formation and Evolutionmentioning

confidence: 99%

“…5.2.3. Kepler-411 bKepler-411 is an active K2V dwarf hosting four planets whose masses were measured bySun et al (2019) with TTVs. Kepler-411 b (P = 3.0 days) is a hot (T eq = 1138 K) sub-Neptune with R p = 2.40 ± 0.05 R ⊕ , M p = 25.6 ± 2.6 M ⊕ , and ρ = 10.3 ± 1.3 g cm −3 .…”

mentioning

confidence: 99%

Another Superdense Sub-Neptune in K2-182 b and Refined Mass Measurements for K2-199 b and c*

Murphy

¹

,

Kosiarek

²

,

Batalha

³

et al. 2021

AJ

8

0

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We combine multiple campaigns of K2 photometry with precision radial velocity measurements from Keck-HIRES to measure the masses of three sub-Neptune-sized planets. We confirm the planetary nature of the massive sub-Neptune K2-182 b (P b = 4.7 days, R b = 2.69 R ⊕) and derive refined parameters for K2-199 b and c (P b = 3.2 days, R b = 1.73 R ⊕ and P c = 7.4 days, R c = 2.85 R ⊕). These planets provide valuable data points in the mass–radius plane, especially as TESS continues to reveal an increasingly diverse sample of sub-Neptunes. The moderately bright (V = 12.0 mag) early K dwarf K2-182 (EPIC 211359660) was observed during K2 campaigns 5 and 18. We find that K2-182 b is potentially one of the densest sub-Neptunes known to date (20 ± 5 M ⊕ and 5.6 ± 1.4 g cm−3). The K5V dwarf K2-199 (EPIC 212779596; V = 12.3 mag), observed in K2 campaigns 6 and 17, hosts two recently confirmed planets. We refine the orbital and planetary parameters for K2-199 b and c by modeling both campaigns of K2 photometry and adding 12 Keck-HIRES measurements to the existing radial velocity data set (N = 33). We find that K2-199 b is likely rocky, at 6.9 ± 1.8 M ⊕ and 7.2 − 2.0 + 2.1 g cm−3, and that K2-199 c has an intermediate density at 12.4 ± 2.3 M ⊕ and 2.9 − 0.6 + 0.7 g cm−3. We contextualize these planets on the mass–radius plane, discuss a small but intriguing population of “superdense” sub-Neptunes (R p < 3 R ⊕, M p >20 M ⊕), and consider our prospects for the planets’ atmospheric characterization.

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Kepler-411: a four-planet system with an active host star

Cited by 55 publications

References 104 publications

Kepler Object of Interest Network

Kepler Object of Interest Network

How does the mass and activity history of the host star affect the population of low-mass planets?

Another Superdense Sub-Neptune in K2-182 b and Refined Mass Measurements for K2-199 b and c*

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