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15891. Transit times of 11 hot Jupiters
ID:
ivo://CDS.VizieR/J/AJ/159/150
Title:
Transit times of 11 hot Jupiters
Short Name:
J/AJ/159/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
Many of the known hot Jupiters are formally unstable to tidal orbital decay. The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit-timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of dP/dt~10^-9^, corresponding to a reduced tidal quality factor of about 2x10^5^. Here, we present a compilation of transit-timing data for WASP-12 and 11 other systems that are especially favorable for detecting orbital decay: KELT-16; WASP-18, 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56. For most of these systems we present new data that extend the time baseline over which observations have been performed. None of the systems besides WASP-12 display convincing evidence for period changes, with typical upper limits on dP/dt on the order of 10^-9^ or 10^-10^, and lower limits on the reduced tidal quality factor on the order of 10^5^. One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity.
15892. Transit times of Kepler-448b and Kepler-693b
ID:
ivo://CDS.VizieR/J/AJ/154/64
Title:
Transit times of Kepler-448b and Kepler-693b
Short Name:
J/AJ/154/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
I report the discovery of non-transiting close companions to two transiting warm Jupiters (WJs), Kepler-448/KOI-12b (orbital period P=17.9days, radius R_p_=1.23_-0.05_^+0.06^R_Jup_) and Kepler-693/KOI-824b (P=15.4days, R_p_=0.91+/-0.05R_Jup_), via dynamical modeling of their transit timing and duration variations (TTVs and TDVs). The companions have masses of 22_-5_^+7^M_Jup_ (Kepler-448c) and 150_-40_^+60^M_Jup_ (Kepler-693c), and both are on eccentric orbits (e=0.65_-0.09_^+0.13^ for Kepler-448c and e=0.47_-0.06_^+0.11^ for Kepler-693c) with periastron distances of 1.5au. Moderate eccentricities are detected for the inner orbits as well (e=0.34_-0.07_^+0.08^ for Kepler-448b and e=0.2_-0.1_^+0.2^ for Kepler-693b). In the Kepler-693 system, a large mutual inclination between the inner and outer orbits (53_-9_^+7^deg or 134_-10_^+11^deg) is also revealed by the TDVs. This is likely to induce a secular oscillation in the eccentricity of the inner WJ that brings its periastron close enough to the host star for tidal star-planet interactions to be significant. In the Kepler-448 system, the mutual inclination is weakly constrained, and such an eccentricity oscillation is possible for a fraction of the solutions. Thus these WJs may be undergoing tidal migration to become hot Jupiters (HJs), although the migration via this process from beyond the snow line is disfavored by the close-in and massive nature of the companions. This may indicate that WJs can be formed in situ and could even evolve into HJs via high-eccentricity migration inside the snow line.
15893. Transit timing observations from Kepler. I.
ID:
ivo://CDS.VizieR/J/ApJS/197/2
Title:
Transit timing observations from Kepler. I.
Short Name:
J/ApJS/197/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
The architectures of multiple planet systems can provide valuable constraints on models of planet formation, including orbital migration, and excitation of orbital eccentricities and inclinations. NASA's Kepler mission has identified 1235 transiting planet candidates. The method of transit timing variations (TTVs) has already confirmed seven planets in two planetary systems. We perform a transit timing analysis of the Kepler planet candidates. We find that at least ~11% of planet candidates currently suitable for TTV analysis show evidence suggestive of TTVs, representing at least ~65 TTV candidates. In all cases, the time span of observations must increase for TTVs to provide strong constraints on planet masses and/or orbits, as expected based on N-body integrations of multiple transiting planet candidate systems (assuming circular and coplanar orbits).
15894. Transit timing variation for 12 planetary pairs
ID:
ivo://CDS.VizieR/J/ApJS/208/22
Title:
Transit timing variation for 12 planetary pairs
Short Name:
J/ApJS/208/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We extract transit timing variation (TTV) signals for 12 pairs of transiting planet candidates that are near first-order mean motion resonances (MMR), using publicly available Kepler light curves (Q0-Q14). These pairs show significant sinusoidal TTVs with theoretically predicted periods, which demonstrate these planet candidates are orbiting and interacting in the same system. Although individual masses cannot be accurately extracted based only on TTVs because of the well-known degeneracy between mass and eccentricity, TTV phases and amplitudes can still place upper limits on the masses of the candidates, confirming their planetary nature. Furthermore, the mass ratios of these planet pairs can be relatively tightly constrained using these TTVs. The planetary pair in KOI 880 seems to have particularly high mass and density ratios, which might indicate very different internal compositions of these two planets. Some of these newly confirmed planets are also near MMR with other candidates in the system, forming unique resonance chains (e.g., KOI 500).
15895. Transit timing variation for 15 planetary pairs. II.
ID:
ivo://CDS.VizieR/J/ApJS/210/25
Title:
Transit timing variation for 15 planetary pairs. II.
Short Name:
J/ApJS/210/25
Date:
21 Oct 2021
Publisher:
CDS
Description:
Following on from Paper I (Cat. J/ApJS/208/22) in this series, I report the confirmation of a further 30 planets in 15 multiple-planet systems via transit timing variations (TTVs), using the publicly available Kepler light curves (Q0-Q16). All 15 pairs are near first-order mean motion resonances, showing sinusoidal TTVs consistent with theoretically predicted periods, which demonstrate they are orbiting and interacting in the same systems. Although individual masses cannot be accurately extracted based only on TTVs (because of the well known degeneracy between mass and eccentricity), the measured TTV phases and amplitudes can still place relatively tight constraints on their mass ratios and upper limits on their masses, which confirm their planetary nature. Some of these systems (KOI-274, KOI-285, KOI-370, and KOI-2672) are relatively bright and thus suitable for further follow-up observations.
15896. 65 Transit-timing variation planets properties
ID:
ivo://CDS.VizieR/J/AJ/162/55
Title:
65 Transit-timing variation planets properties
Short Name:
J/AJ/162/55
Date:
16 Mar 2022 00:18:00
Publisher:
CDS
Description:
Transit surveys have revealed a significant population of compact multiplanet systems, containing several sub-Neptune-mass planets on close-in, tightly-packed orbits. These systems are thought to have formed through a final phase of giant impacts, which would tend to leave systems close to the edge of stability. Here, we assess this hypothesis, comparing observed eccentricities in systems exhibiting transit-timing variations versus the maximum eccentricities compatible with long-term stability. We use the machine-learning classifier SPOCK (Tamayo et al.) to rapidly classify the stability of numerous initial configurations and hence determine these stability limits. While previous studies have argued that multiplanet systems are often maximally packed, in the sense that they could not host any additional planets, we find that the existing planets in these systems have measured eccentricities below the limits allowed by stability by a factor of 2-10. We compare these results against predictions from the giant-impact theory of planet formation, derived from both N-body integrations and theoretical expectations that, in the absence of dissipation, the orbits of such planets should be distributed uniformly throughout the phase space volume allowed by stability. We find that the observed systems have systematically lower eccentricities than this scenario predicts, with a median eccentricity about four times lower than predicted. This suggests that, if these systems formed through giant impacts, then some dissipation must occur to damp their eccentricities. This may occur through interactions with the natal gas disk or a leftover population of planetesimals, or over longer timescales through the coupling of tidal and secular processes.
15897. Transit timing variations of Kepler-90g and h
ID:
ivo://CDS.VizieR/J/AJ/161/202
Title:
Transit timing variations of Kepler-90g and h
Short Name:
J/AJ/161/202
Date:
10 Dec 2021
Publisher:
CDS
Description:
Exoplanet transit-timing variations (TTVs) caused by gravitational forces between planets can be used to determine planetary masses and orbital parameters. Most of the observed TTVs are small and sinusoidal in time, leading to degeneracies between the masses and orbital parameters. Here we report a TTV analysis of Kepler-90g and Kepler-90h, which exhibit large TTVs up to 25hr. With optimization, we find a unique solution that allows us to constrain all of the orbital parameters. The best-fit masses for Kepler-90g and 90h are 15.0_-0.8_^+0.9^M{Earth} (Earth mass) and 203_-5_^+5^M_{Earth}, respectively, with Kepler-90g having an unusually low apparent density of 0.15{+/-}0.05g/cm^3^. The uniqueness of orbital parameter solution enables a long-term dynamical integration, which reveals that although their periods are close to 2:3 orbital resonance, they are not locked in resonance, and the configuration is stable over billions of years. The dynamical history of the system suggests that planet interactions are able to raise the eccentricities and break the resonant lock after the initial formation.
15898. Transit timing variations of 145 Kepler planets
ID:
ivo://CDS.VizieR/J/AJ/154/5
Title:
Transit timing variations of 145 Kepler planets
Short Name:
J/AJ/154/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conduct a uniform analysis of the transit timing variations (TTVs) of 145 planets from 55 Kepler multiplanet systems to infer planet masses and eccentricities. Eighty of these planets do not have previously reported mass and eccentricity measurements. We employ two complementary methods to fit TTVs: Markov chain Monte Carlo simulations based on N-body integration, and an analytic fitting approach. Mass measurements of 49 planets, including 12 without previously reported masses, meet our criterion for classification as robust. Using mass and radius measurements, we infer the masses of planets' gaseous envelopes for both our TTV sample and transiting planets with radial velocity observations. Insight from analytic TTV formulae allows us to partially circumvent degeneracies inherent to inferring eccentricities from TTV observations. We find that planet eccentricities are generally small, typically a few percent, but in many instances are nonzero.
15899. Transmission Spectroscopy Metric of exoplanets
ID:
ivo://CDS.VizieR/J/AJ/159/239
Title:
Transmission Spectroscopy Metric of exoplanets
Short Name:
J/AJ/159/239
Date:
21 Oct 2021
Publisher:
CDS
Description:
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. HD97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight Microvariability and Oscillations of Stars Telescope (MOST) transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1-1.7{mu}m reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, 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 ~>100 solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295{+/-}0.000005, with a best-fit transit time center at T0=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{+/-}2days) and stellar activity cycle (9.6yr) of the host star HD97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000K and with sizes between 1R_{Earth}_ and 4R_{Earth}_. We find that at least a third of small planets cooler than 1000K can be well characterized using James Webb Space Telescope, and of those, HD97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization.
15900. TRAPPIST-South UCD Transit Survey
ID:
ivo://CDS.VizieR/J/MNRAS/497/3790
Title:
TRAPPIST-South UCD Transit Survey
Short Name:
J/MNRAS/497/3790
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey - a prototype of the SPECULOOS transit search conducted with the TRAPPIST-South robotic telescope in Chile from 2011 to 2017 - to estimate the occurrence rate of close-in planets such as TRAPPIST-1b orbiting ultra-cool dwarfs. For this purpose, the photometric data of 40 nearby ultra-cool dwarfs were reanalysed in a self-consistent and fully automated manner starting from the raw images. The pipeline developed specifically for this task generates differential light curves, removes non-planetary photometric features and stellar variability, and searches for transits. It identifies the transits of TRAPPIST-1b and TRAPPIST-1c without any human intervention. To test the pipeline and the potential output of similar surveys, we injected planetary transits into the light curves on a star-by-star basis and tested whether the pipeline is able to detect them. The achieved photometric precision enables us to identify Earth-sized planets orbiting ultra-cool dwarfs as validated by the injection tests. Our planet-injection simulation further suggests a lower limit of 10 per cent on the occurrence rate of planets similar to TRAPPIST-1b with a radius between 1 and 1.3 R_{Earth}_ and the orbital period between 1.4 and 1.8d.

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