A Comprehensive Study of Kepler Phase Curves and Secondary Eclipses: Temperatures and Albedos of Confirmed Kepler Giant Planets

Angerhausen, Daniel; DeLarme, Emily; Morse, Jon A.

doi:10.1086/683797

Cited by 146 publications

(162 citation statements)

References 88 publications

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“…The depth of the planetary eclipse would imply a planet-tostar surface brightness ratio of f = (8.93 ± 4.13) × 10 −4 , allowing us to constrain the geometric A g and Bond A b albedo of the planet. From the effective stellar temperature, eccentricity, and scaled semi-major listed in Table 5, and assuming A g = 1.5 × A B and heat redistribution factor between 1/4 and 2/3, we found tentative values of A g = 0.055 ± 0.028, A B = 0.037 ± 0.019, and a planet brightness temperature of T br = 1950±250 K. This would make Kepler-423b one of the gas-giant planets with lowest Bond albedo known so far (see, e.g., Angerhausen et al 2014). …”

Section: Secondary Eclipse and Planet Albedosupporting

confidence: 55%

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Parviainen

Deeg

Lanza

et al. 2015

A&A

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We report the spectroscopic confirmation of the Kepler object of interest , a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1−17) with high-precision radial velocity measurements taken with the FIES spectrograph at the Nordic Optical Telescope. We simultaneously modelled the photometric and spectroscopic data-sets using Bayesian approach coupled with Markov chain Monte Carlo sampling. We found that the Kepler pre-search data conditioned light curve of Kepler-423 exhibits quarter-to-quarter systematic variations of the transit depth, with a peak-to-peak amplitude of ∼4.3% and seasonal trends reoccurring every four quarters. We attributed these systematics to an incorrect assessment of the quarterly variation of the crowding metric. The host star Kepler-423 is a G4 dwarf with M = 0.85 ± 0.04 M , R = 0.95 ± 0.04 R , T eff = 5560 ± 80 K, [M/H] = −0.10 ± 0.05 dex, and with an age of 11 ± 2 Gyr. The planet Kepler-423b has a mass of M p = 0.595 ± 0.081 M Jup and a radius of R p = 1.192 ± 0.052 R Jup , yielding a planetary bulk density of ρ p = 0.459 ± 0.083 g cm −3 . The radius of Kepler-423b is consistent with both theoretical models for irradiated coreless giant planets and expectations based on empirical laws. The inclination of the stellar spin axis suggests that the system is aligned along the line of sight. We detected a tentative secondary eclipse of the planet at a 2σ confidence level (∆F ec = 14.2 ± 6.6 ppm) and found that the orbit might have a small non-zero eccentricity of 0.019 +0.028 −0.014 . With a Bond albedo of A B = 0.037 ± 0.019, Kepler-423b is one of the gas-giant planets with the lowest albedo known so far.

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Section: Secondary Eclipse and Planet Albedosupporting

confidence: 55%

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Parviainen

Deeg

Lanza

et al. 2015

A&A

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“…However, as we noted and Angerhausen et al (2014) concluded as well, the detection of the secondary eclipse is neither clear nor conclusive. Moreover, given their derived mass for this companion with a Jupiter-like radius, it is difficult to explain their proposed stellar nature.…”

Section: Resultsmentioning

confidence: 56%

“…Based on transit-fitting analysis and a claimed detection of the secondary eclipse, Esteves et al (2013) concluded that the object emits light so they rejected it as a planet. In contrast, Angerhausen et al (2014) provided a high-level analysis of the entire light-curve (encompassing all available Kepler observations). They detected several dimmings in the phase-folded light-curve, achieved similar conclusions as Lillo-Box et al (2014b), and suggested that the detected dimmings are poorly explained with a secondary eclipse alone.…”

Section: Introductionmentioning

confidence: 99%

Radial velocity confirmation of Kepler-91 b

Lillo-Box

Barrado

Henning

et al. 2014

A&A

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The object transiting the star Kepler-91 was recently assessed as being of planetary nature. The confirmation was achieved by analysing the light-curve modulations observed in the Kepler data. However, quasi-simultaneous studies claimed a self-luminous nature for this object, thus rejecting it as a planet. In this work, we apply an independent approach to confirm the planetary mass of Kepler-91b by using multi-epoch high-resolution spectroscopy obtained with the Calar Alto Fiber-fed Echelle spectrograph (CAFE). We obtain the physical and orbital parameters with the radial velocity technique. In particular, we derive a value of 1.09 ± 0.20 M Jup for the mass of Kepler-91b, in excellent agreement with our previous estimate that was based on the orbital brightness modulation.

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“…The inferred geometric albedo, A g = 0.25-0.38 (4,6,7,10,14), reveals a planet of reflectivity comparable to the solar system giants (A g = 0.4-0.5), which is unexpectedly high for a close-in gas planet. Theory indeed predicts that the strong stellar irradiation that a planet in such an orbit experiences strips off reflective clouds, rendering the planet dark (A g < 0.1) (22,25).…”

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confidence: 88%

Probing exoplanet clouds with optical phase curves

Muñoz

Isaak

2015

Proc. Natl. Acad. Sci. U.S.A.

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Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve-from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5.close-in giant | exoplanets | atmospheric characterization | clouds | optical phase curves P hase curves provide unique insight into the atmosphere of a planet, a fact well known and tested in solar system exploration (1-3). Disentangling the information encoded in a phase curve is a complex process however, and interpretations can be faced with degeneracies. The potential of phase curves to characterize exoplanet atmospheres, particularly in combination with other techniques, is tantalizing. Phase curves observed over all orbital phases (OPs) are available for a few close-in planets in the optical (passband central wavelengths λ < 0.8 μm) (4-15) and the infrared (1 μm ≤ λ ≤ 24 μm) (16-19). At infrared wavelengths the measured flux from hot planets is typically dominated by thermal emission. In the optical, both thermal emission and reflected starlight contribute, with the relative size of the contributions dependent on the measurement wavelength as well as on the temperature of the atmosphere and the occurrence of condensates (20-25).Kepler-7b (26) is one of the ∼1,000 planets discovered by the Kepler mission. Its inferred mass M p (= 0.44 M J ; J for Jupiter) and radius R p (= 1.61 R J ) result in an unusually low bulk density (0.14 g·cm −3 ) that is inconsistent with current models of giant planet interiors (27, 28). Kepler-7b orbits a quiet G-type star of effective temperature T ⋆ = 5,933 K every 4.89 d (orbital distance a = 0.062 astronomical units) (6, 7), and tidal forces have likely synchronized its orbit and spin motions. Taken together these set a planet equilibrium temperature T eq ≤ 1,935 K.Kepler photometry (0.4-0.9 μm) of the star-planet system has enabled the optical study of 10,14). The inferred geometric albedo, A g = 0. 25-0.38 (4, 6, 7, 10...

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A Comprehensive Study of Kepler Phase Curves and Secondary Eclipses: Temperatures and Albedos of Confirmed Kepler Giant Planets

Cited by 146 publications

References 88 publications

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star

Radial velocity confirmation of Kepler-91 b

Probing exoplanet clouds with optical phase curves

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