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Register a new userThe Possible Orbital Decay and Transit Timing Variations of the Planet WASP-43b
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Motivated by the previously reported high orbital decay rate of the planet WASP-43b, eight newly transit light curves are obtained and presented. Together with other data in literature, we perform a self-consistent timing analysis with data covering a timescale of 1849 epochs. The results give an orbital decay rate dP/dt = -0.02890795pm 0.00772547 sec/year, which is one order smaller than previous values. This slow decay rate corresponds to a normally assumed theoretical value of stellar tidal dissipation factor. In addition, through the frequency analysis, the transit timing variations presented here are unlikely to be periodic, but could be signals of a slow orbital decay.
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We present 15 new transit observations of the exoplanet WASP-43b in the $i$,$g$, and $R$ filters with the 1.0-m telescopes of Las Cumbres Observatory Global Telescope (LCOGT) Network and the IAC80 telescope. We combine our 15 new light curves with 52 others from literature, to analyze homogeneously all the available transit light curves of this exoplanet. By extending the time span of the monitoring of the transits to more than $5~yr$, and by analyzing the individual mid-times of 72 transits, we study the proposed shortening of the orbital period of WASP-43b. We estimate that the times of transit are well-matched by our updated ephemeris equation, using a constant orbital period. We estimate an orbital period change rate no larger than $dot{P}=-0.02 pm 6.6~ms~yr^{-1}$, which is fully consistent with a constant period. Based on the timing analysis, we discard stellar tidal dissipation factors $Q_{*}<10^{5}$. In addition, with the modelling of the transits we update the system parameters: $a/Rs=4.867(23)$, $i=82.11(10)^{circ}$ and $R_p/R_s=0.15942(41)$, noticing a difference in the relative size of the planet between optical and NIR bands.
Transits in the planetary system WASP-4 were recently found to occur 80s earlier than expected in observations from the TESS satellite. We present 22 new times of mid-transit that confirm the existence of transit timing variations, and are well fitted by a quadratic ephemeris with period decay dP/dt = -9.2 +/- 1.1 ms/yr. We rule out instrumental issues, stellar activity and the Applegate mechanism as possible causes. The light-time effect is also not favoured due to the non-detection of changes in the systemic velocity. Orbital decay and apsidal precession are plausible but unproven. WASP-4b is only the third hot Jupiter known to show transit timing variations to high confidence. We discuss a variety of observations of this and other planetary systems that would be useful in improving our understanding of WASP-4 in particular and orbital decay in general.
We have observed 7 new transits of the `hot Jupiter WASP-5b using a 61 cm telescope located in New Zealand, in order to search for transit timing variations (TTVs) which can be induced by additional bodies existing in the system. When combined with other available photometric and radial velocity (RV) data, we find that its transit timings do not match a linear ephemeris; the best fit chi^2 values is 32.2 with 9 degrees of freedom which corresponds to a confidence level of 99.982 % or 3.7 sigma. This result indicates that excess variations of transit timings has been observed, due either to unknown systematic effects or possibly to real TTVs. The TTV amplitude is as large as 50 s, and if this is real, it cannot be explained by other effects than that due to an additional body or bodies. From the RV data, we put an upper limit on the RV amplitude caused by the possible secondary body (planet) as 21 m s^{-1}, which corresponds to its mass of 22-70 M_{Earth} over the orbital period ratio of the two planets from 0.2 to 5.0. From the TTVs data, using the numerical simulations, we place more stringent limits down to 2 M_{Earth} near 1:2 and 2:1 mean motion resonances (MMRs) with WASP-5b at the 3 sigma level, assuming that the two planets are co-planer. We also put an upper limit on excess of Trojan mass as 43 M_{Earth} (3 sigma) using both RV and photometric data. We also find that if the possible secondary planet has non- or a small eccentricity, its orbit would likely be near low-order MMRs. Further follow-up photometric and spectroscopic observations will be required to confirm the reality of the TTV signal, and results such as these will provide important information for the migration mechanisms of planetary systems.
We report nine new transit epochs of the extrasolar planet, observed in the Bessell-I band with SOAR at the Cerro Pachon Observatory and with the SMARTS 1-m Telescope at CTIO, between August 2008 and October 2009. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variations (TTVs) analysis of its orbit. We find no evidence of TTVs RMS variations larger than 1 min over a 3 year time span. This result discards the presence of planets more massive than about 5 M_earth, 1 M_earth and 2 M_earth around the 1:2, 5:3 and 2:1 orbital resonances. These new detection limits exceed by ~5-30 times the limits imposed by current radial velocity observations in the Mean Motion Resonances of this system. Our search for the variation of other parameters, such as orbital inclination and transit depth also yields negative results over the total time span of the transit observations. This result supports formation theories that predict a paucity of planetary companions to Hot Jupiters.
The Kepler Mission is monitoring the brightness of ~150,000 stars searching for evidence of planetary transits. As part of the Hunt for Exomoons with Kepler (HEK) project, we report a planetary system with two confirmed planets and one candidate planet discovered using the publicly available data for KOI-872. Planet b transits the host star with a period P_b=33.6d and exhibits large transit timing variations indicative of a perturber. Dynamical modeling uniquely detects an outer nontransiting planet c near the 5:3 resonance (P_c=57.0d) of mass 0.37 times that of Jupiter. Transits of a third planetary candidate are also found: a 1.7-Earth radius super-Earth with a 6.8d period. Our analysis indicates a system with nearly coplanar and circular orbits, reminiscent of the orderly arrangement within the solar system.
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