Near-infrared transit photometry of the exoplanet HD 149026b

Abstract

The transiting exoplanet HD 149026b is an important case for theories of planet formation and planetary structure, because the planet's relatively small size has been interpreted as evidence for a highly metal-enriched composition. We present observations of 4 transits with the Near Infrared Camera and Multi-Object Spectrometer on the Hubble Space Telescope, within a wavelength range of 1.1--2.0 $\mu$m. Analysis of the light curve gives the most precise estimate yet of the stellar mean density, ${\rho }_{\star }=0.497_{-0.057}^{+0.042}$ g cm${}^{-3}$. By requiring agreement between the observed stellar properties (including ${\rho }_{\star }$) and stellar evolutionary models, we refine the estimate of the stellar radius: $R_{\star }=1.541_{-0.042}^{+0.046}$ $R_\sun$. We also find a deeper transit than has been measured at optical and mid-infrared wavelengths. Taken together, these findings imply a planetary radius of $R_p=0.813_{-0.025}^{+0.027}$ $R_{\mathrm{Jup}}$, which is larger than earlier estimates. Models of the planetary interior still require a metal-enriched composition, although the required degree of metal enrichment is reduced. It is also possible that the deeper NICMOS transit is caused by wavelength-dependent absorption by constituents in the planet's atmosphere, although simple model atmospheres do not predict this effect to be strong enough to account for the discrepancy. We use the 4 newly-measured transit times to compute a refined transit ephemeris.

18 pages, 13 figures, accepted for publication in ApJ

References in corpus (21)

• Validation of the new Hipparcos reduction
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Improved parameters for extrasolar transiting planets
• Possible Solutions to the Radius Anomalies of Transiting Giant Planets
• Improving Stellar and Planetary Parameters of Transiting Planet Systems: The Case of TrES-2
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• Analytic Approximations for Transit Light Curve Observables, Uncertainties, and Covariances
• XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary
• XO-3b: A Massive Planet in an Eccentric Orbit Transiting an F5V Star
• Homogeneous studies of transiting extrasolar planets. II. Physical properties
• The Transit Light Curve Project. III. Tres Transits of TrES-1
• Properties of analytic transit light curve models
• Using Transit Timing Observations to Search for Trojans of Transiting Extrasolar Planets
• On the Origin of HD149026b
• The AGN and Gas Disk in the Low Surface Brightness Galaxy PGC045080
• Empirical Constraints on Trojan Companions and Orbital Eccentricities in 25 Transiting Exoplanetary Systems
• Transit Photometry of the Core-Dominated Planet HD 149026b
• A Precise Estimate of the Radius of the Exoplanet HD 149026b from Spitzer Photometry
• Five New Transits of the Super-Neptune HD 149026
• The formation of HD 149026 b

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