HATnet Results

Additional low-mass planet in HAT-P-37 system?

The Transit Timing and Atmosphere of Hot Jupiter HAT-P-37b

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The transit timing variation (TTV) and transmission spectroscopy analyses of the planet HAT-P-37b, which is a hot Jupiter orbiting an G-type star, were performed. Nine new transit light curves are obtained and analysed together with 21 published light curves from the literature. The updated physical parameters of HAT-P-37b are presented. The TTV analyses show a possibility that the system has an additional planet which induced the TTVs amplitude signal of 1.74 ± 0.17 minutes. If the body is located near the 1:2 mean motion resonance orbit, the sinusoidal TTV signal could be caused by the gravitational interaction of a sub-Earth mass planet with mass of 0.06 M⊕. From the analysis of an upper mass limit for the second planet, the Saturn mass planet with orbital period less than 6 days is excluded. The broad-band transmission spectra of HAT-P-37b favours a cloudy atmospheric model with an outlier spectrum in B-filter.

Orbital parameters to be revised for HAT-P-29 b or a second planet in HAT-P-29 system?

https://exofop.ipac.caltech.edu/tess/target.php?id=250707118

ExoFOP TESS lists a nearly equal-radius transiting planet candidate with orbital period of 11.44 days. An alias of the 5.72 d period seems likely too.

Revisiting the Transit Timing and Atmosphere Characterization of the Neptune-mass Planet HAT-P-26 b
https://arxiv.org/abs/2303.03610

Clues for a second ca. 6.4 Earth-mass planet with orbital period of 8.47 days in 1:2 resonance.

Revisiting Orbital Evolution in HAT-P-2 b and Confirmation of HAT-P-2 c

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One possible formation mechanism for Hot Jupiters is that high-eccentricity gas giants experience tidal interactions with their host star that cause them to lose orbital energy and migrate inwards. We study these types of tidal interactions in an eccentric Hot Jupiter called HAT-P-2 b, which is a system where a long-period companion has been suggested, and hints of orbital evolution (de Wit et al. 2017) were detected. Using five additional years of radial velocity (RV) measurements, we further investigate these phenomena. We investigated the long-period companion by jointly fitting RVs and Hipparcos-Gaia astrometry and confirmed this long-period companion, significantly narrowed down the range of possible periods (P2=8500+2600−1500 days), and determined that it must be a substellar object (10.7+5.2−2.2 Mj). We also developed a modular pipeline to simultaneously model rapid orbital evolution and the long-period companion. We find that the rate and significance of evolution are highly dependent on the long-period companion modeling choices. In some cases the orbital rates of change reached de/dt=3.28+1.75−1.72⋅10−3/year, dω/dt=1.12±0.22∘/year which corresponds to a ∼321 year apsidal precession period. In other cases, the data is consistent with de/dt=7.67±18.6⋅10−4/year, dω/dt=0.76±0.24∘/year. The most rapid changes found are significantly larger than the expected relativistic precession rate and could be caused by transient tidal planet-star interactions. To definitively determine the magnitude and significance of potential orbital evolution in HAT-P-2 b, we recommend further monitoring with RVs and precise transit and eclipse timings.