Posted Content•
The Impact of Transit Observations on Planetary Physics
TL;DR: In this paper, the authors highlight the importance of transit observations on understanding the physics of planetary atmospheres and interiors, and calculate mass-radius relations for water-rock-iron and gas giant planets and examine these relations in light of current and future transit observations.
Abstract: We highlight the importance of transit observations on understanding the physics of planetary atmospheres and interiors. Transmission spectra and emission spectra allow us to characterize this exotic atmospheres, which possess TiO, VO, H2O, CO, Na, and K, as principal absorbers. We calculate mass-radius relations for water-rock-iron and gas giant planets and examine these relations in light of current and future transit observations. A brief review is given of mechanisms that could lead to the large radii observed for some transiting planets.
Citations
More filters
TL;DR: In this article, the authors reported the discovery of a planet transiting a moderately faint (V=12.3 mag) late F star, with an orbital period of 3.92289 +/- 0.00004 days.
Abstract: We report the discovery of a planet transiting a moderately faint (V=12.3 mag) late F star, with an orbital period of 3.92289 +/- 0.00004 days. From the transit light curve and radial velocity measurements we determine that the radius of the planet is R_p = 1.40 +/- 0.06 R_Jup and that the mass is M_p = 0.78 +/- 0.09 M_Jup. The density of the new planet, rho = 0.35 +/- 0.06 g cm^{-3}, fits to the low-density tail of the currently known transiting planets. We find that the center of transit is at T_c = 2454417.9077 +/- 0.0003 (HJD), and the total transit duration is 0.143 +/- 0.004 days. The host star has M_s = 1.28 +/- 0.13 M_Sun and R_s = 1.32 +/- 0.07 R_Sun.
42 citations
TL;DR: In this article, the authors presented multi-band photometric follow-up observations of the transiting planet GJ 436b, consisting of 5 new ground-based transit light curves obtained in May 2007.
Abstract: This paper presents multi-band photometric follow-up observations of the Neptune-mass transiting planet GJ 436b, consisting of 5 new ground-based transit light curves obtained in May 2007. Together with one already published light curve we have at hand a total of 6 light curves, spanning 29 days. The analysis of the data yields an orbital period P = 2.64386+-0.00003 days, mid-transit time T_c [HJD] =2454235.8355+-0.0001, planet mass M_p = 23.1+-0.9 M_{\earth} = 0.073+-0.003 M_{Jup}, planet radius R_p = 4.2+-0.2 R_{\earth} = 0.37+-0.01 R_{Jup} and stellar radius R_s = 0.45+-0.02 R_{\sun}. Our typical precision for the mid transit timing for each transit is about 30 seconds. We searched the data for a possible signature of a second planet in the system through transit timing variations (TTV) and variation of the impact parameter. The analysis could not rule out a small, of the order of a minute, TTV and a long-term modulation of the impact parameter, of the order of +0.2 year^{-1}.
33 citations
Posted Content•
TL;DR: In this paper, the response of radiative atmospheres is computed in a hydrostatic model which treats the insolation as a time-dependent heat source, and solves for thermal radiation using flux-limited diffusion.
Abstract: Time-dependent insolation in a planetary atmosphere induces a mass quadrupole upon which the stellar tidal acceleration can exert a force This "thermal tide" force can give rise to secular torques on the planet and orbit as well as radial forces causing eccentricity evolution We apply this idea to the close-in gas giant exoplanets ("hot Jupiters") The response of radiative atmospheres is computed in a hydrostatic model which treats the insolation as a time-dependent heat source, and solves for thermal radiation using flux-limited diffusion Fully nonlinear numerical simulations are compared to solutions of the linearized equations, as well as analytic approximations, all of which are in good agreement We find generically that thermal tide density perturbations {\it lead} the semi-diurnal forcing As a result thermal tides can generate asynchronous spin and eccentricity Our results are as follows: (1) Departure from synchronous spin is significant for hot Jupiters, and increases with orbital period (2) Ongoing gravitational tidal dissipation in spin equilibrium leads to steady-state internal heating rates up to $\sim 10^{28} {\rm erg\ s^{-1}}$ If deposited sufficiently deep, these heating rates may explain the anomalously large radii of many hot Jupiters in terms of a "tidal main sequence" where cooling balances tidal heating At fixed stellar type, planet mass and tidal $Q$, planetary radius increases strongly toward the star inside orbital periods $\la 2$ weeks (3) There exists a narrow window in orbital period where small eccentricities, $e$, grow exponentially with a large rate This window may explain the $\sim 1/4$ of hot Jupiters which should have been circularized by the gravitational tide long ago, but are observed to have significant nonzero $e$(Abridged)
18 citations
Cites background from "The Impact of Transit Observations ..."
...This effect can explain radii Rp ∼ (1.0 − 1.2) ×RJ , but is insufficient to explain the radii of a significant fraction of the population with Rp ∼ (1.2 − 1.8) × RJ (see Fortney 2008 for a recent review)....
[...]
...1.2RJ and below, but have difficulty slowing the cooling enough to explain planets with R & 1.2RJ (e.g. Fortney 2008)....
[...]
TL;DR: In this paper, two consecutive transits of planetary companion OGLE-TR-111b were observed in the I band, and the timing of the transits cannot be explained by a constant period, and that the observed variations cannot be originated by the presence of a satellite.
Abstract: Two consecutive transits of planetary companion OGLE-TR-111b were observed in the I band. Combining these observations with data from the literature, we find that the timing of the transits cannot be explained by a constant period, and that the observed variations cannot be originated by the presence of a satellite. However, a perturbing planet with the mass of the Earth in an exterior orbit could explain the observations if the orbit of OGLE-TR-111b is eccentric. We also show that the eccentricity needed to explain the observations is not ruled out by the radial velocity data found in the literature.