Probing<i>Kepler</i>’s hottest small planets via homogeneous search and analysis of optical secondary eclipses and phase variations

Singh, V.; Bonomo, A. S.; Scandariato, G.; Cibrario, N.; Barbato, D.; Fossati, L.; Pagano, I.; Sozzetti, A.

doi:10.1051/0004-6361/202039037

Cited by 12 publications

(4 citation statements)

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“…The spectrum agrees well with the originally published eclipse depth. Subsequent analysis suggested that the eclipse depth may be even higher (Sheets & Deming 2014;Singh et al 2022). The thermal inversion model agrees with these values to within 2.4 and 3.6σ, respectively.…”

Section: Evidence For a Thin Rock Vapor Atmospherementioning

confidence: 61%

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

Zieba

Zilinskas

Kreidberg

et al. 2022

A&A

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K2-141 b is a transiting, small (1.5 R⊕) ultra-short-period (USP) planet discovered by the Kepler space telescope orbiting a K-dwarf host star every 6.7 h. The planet's high surface temperature of more than 2000 K makes it an excellent target for thermal emission observations. Here we present 65 h of continuous photometric observations of K2-141 b collected with Spitzer's Infrared Array Camera (IRAC) Channel 2 at 4.5 μm spanning ten full orbits of the planet. We measured an infrared eclipse depth of ${f_{{{\rm{p}} \mathord{\left/ {\vphantom {{\rm{p}} {{{\rm{f}}_{\rm{*}}}}}} \right. \kern-\nulldelimiterspace} {{{\rm{f}}_{\rm{*}}}}}}} = 142.9_{ - 39.0}^{38.5}$ ppm and a peak to trough amplitude variation of $A = 120.6_{ - 43.0}^{42.3}$ ppm. The best fit model to the Spitzer data shows no significant thermal hotspot offset, in contrast to the previously observed offset for the well-studied USP planet 55 Cnc e. We also jointly analyzed the new Spitzer observations with the photometry collected by Kepler during two separate K2 campaigns. We modeled the planetary emission with a range of toy models that include a reflective and a thermal contribution. With a two-temperature model, we measured a dayside temperature of ${T_{{\rm{p,d}}}} = 2049_{ - 359}^{362}$ K and a night-side temperature that is consistent with zero (Tp,n < 1712 K at 2σ). Models with a steep dayside temperature gradient provide a better fit to the data than a uniform dayside temperature (ΔBIC = 22.2). We also found evidence for a nonzero geometric albedo ${A_{\rm{g}}} = 0.282_{ - 0.078}^{0.070}$. We also compared the data to a physically motivated, pseudo-2D rock vapor model and a 1D turbulent boundary layer model. Both models fit the data well. Notably, we found that the optical eclipse depth can be explained by thermal emission from a hot inversion layer, rather than reflected light. A thermal inversion may also be responsible for the deep optical eclipse observed for another USP, Kepler-10 b. Finally, we significantly improved the ephemerides for K2-141 b and c, which will facilitate further follow-up observations of this interesting system with state-of-the-art observatories such as James Webb Space Telescope.

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Section: Evidence For a Thin Rock Vapor Atmospherementioning

confidence: 61%

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

Zieba

Zilinskas

Kreidberg

et al. 2022

A&A

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“…where φ is the planet's orbital phase. We do not go into the mathematical details of these terms (we refer the reader to Esteves et al 2013;Singh et al 2022, and references therein), but we give only a brief description and the list of parameters that define each of them.…”

Section: Light Curve Fittingmentioning

confidence: 99%

Phase curve and geometric albedo of WASP-43b measured with CHEOPS, TESS, and HST WFC3/UVIS

Scandariato

Singh

Kitzmann

et al. 2022

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Context. Observations of the phase curves and secondary eclipses of extrasolar planets provide a window onto the composition and thermal structure of the planetary atmospheres. For example, the photometric observations of secondary eclipses lead to the measurement of the planetary geometric albedo, A g , which is an indicator of the presence of clouds in the atmosphere. Aims. In this work, we aim to measure the A g in the optical domain of WASP-43b, a moderately irradiated giant planet with an equilibrium temperature of ∼1400 K. Methods. For this purpose, we analyzed the secondary eclipse light curves collected by CHEOPS together with TESS along with observations of the system and the publicly available photometry obtained with HST WFC3/UVIS. We also analyzed the archival infrared observations of the eclipses and retrieve the thermal emission spectrum of the planet. By extrapolating the thermal spectrum to the optical bands, we corrected for the optical eclipses for thermal emission and derived the optical A g . Results. The fit of the optical data leads to a marginal detection of the phase-curve signal, characterized by an amplitude of 160 ± 60 ppm and 80 +60 −50 ppm in the CHEOPS and TESS passbands, respectively, with an eastward phase shift of ∼ 50 • (1.5σ detection). The analysis of the infrared data suggests a non-inverted thermal profile and solar-like metallicity. The combination of the optical and infrared analyses allows us to derive an upper limit for the optical albedo of A g < 0.087, with a confidence of 99.9%. Conclusions. Our analysis of the atmosphere of WASP-43b places this planet in the sample of irradiated hot Jupiters, with monotonic temperature-pressure profile and no indication of condensation of reflective clouds on the planetary dayside.

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“…Separation of A b and is not possible using the occultation alone. However, by measuring the phase curve, one may attempt to derive the night side emissivity that depends solely on (Singh et al 2022).…”

Section: The Emission Spectrummentioning

confidence: 99%

Near-infrared and optical emission of WASP-5 b

Kovács

Dékány

Karamiqucham

et al. 2022

A&A

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Context. Thermal emission from extrasolar planets makes it possible to study important physical processes in their atmospheres and derive more precise orbital elements. Aims. By using new near-infrared (NIR) and optical data, we examine how these data constrain the orbital eccentricity and the thermal properties of the planet atmosphere. Methods. The full light curves acquired by the TESS satellite from two sectors are used to put an upper limit on the amplitude of the phase variation of the planet and estimate the occultation depth. Two previously published observations and one followup observation (published herein) in the 2MASS K (Ks) band are employed to derive a more precise occultation light curve in this NIR waveband. Results. The merged occultation light curve in the Ks band comprises 4515 data points. The data confirm the results of the earlier eccentricity estimates, suggesting a circular orbit of: e = 0.005 ± 0.015. The high value of the flux depression of (2.70 ± 0.14) ppt in the Ks band excludes simple black body emission at the 10σ level and also disagrees with current atmospheric models at the (4–7)σ level. From analysis of the TESS data, in the visual band we find tentative evidence for a near-noise-level detection of the secondary eclipse, and place constraints on the associated amplitude of the phase variation of the planet. A formal box fit yields an occultation depth of (0.157 ± 0.056) ppt. This implies a relatively high geometric albedo of Ag = 0.43 ± 0.15 for fully efficient atmospheric circulation and Ag = 0.29 ± 0.15 for no circulation at all. No preference can be seen for either the oxygen-enhanced or the carbon-enhanced atmosphere models.

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ProbingKepler’s hottest small planets via homogeneous search and analysis of optical secondary eclipses and phase variations

Cited by 12 publications

References 91 publications

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

Phase curve and geometric albedo of WASP-43b measured with CHEOPS, TESS, and HST WFC3/UVIS

Near-infrared and optical emission of WASP-5 b

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