Atmosphere, Interior, and Evolution of the Metal-rich Transiting Planet HD 149026b

By Jon Fortney, D. Saumon, M. Marley, K. Lodders, R. Freedman. 2005

159 citations recorded by the source corpus.

We investigate the atmosphere and interior of the new transiting planet HD 149026b, which appears to be very rich in heavy elements. We first compute model atmospheres at metallicities ranging from solar to 10 times solar and show how for cases with high metallicity or inefficient redistribution of energy from the dayside, the planet may develop a hot stratosphere due to absorption of stellar flux by TiO and VO. The spectra predicted by these models are very different than cooler atmosphere models without stratospheres. The spectral effects are potentially detectable with the Spitzer Space Telescope. In addition, the models with hot stratospheres lead to a large limb brightening, rather than darkening. We compare the atmosphere of HD 149026b to other well-known transiting planets, including the recently discovered HD 189733b, which we show has a planet-to-star flux ratio twice that of HD 209458 and TrES-1. The methane abundance in the atmosphere of HD 189733b is a sensitive indicator of atmospheric temperature and metallicity and can be constrained with Spitzer IRAC observations. We then turn to interior studies of HD 149026b and use a grid of self-consistent model atmospheres and high-pressure equations of state for all components to compute thermal evolution models of the planet. We estimate that the mass of heavy elements within the planet is in the range of 60-93 M⊕. Finally, we discuss trends in the radii of transiting planets with metallicity in light of this new member of the class.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3abfcca01ac9718ccf9c5dab4edd34a7c011455b

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In Astronomy and Astrophysics

1. Jon Fortney
2. N. Madhusudhan
3. A. Showman
4. M. Marley
5. M. Line
6. Sara Seager
7. H. Knutson
8. V. Parmentier

Citations in the corpus

• A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres (2007, methodology): “At that point, looking at the work of Fortney et al. (2006b) and especially Hubeny et al. (2003), Harrington et al. (2007) could have postulated that all objects more irradiate than HD 149026b may possess inversions due to TiO/VO opacity, but given the single-band detection of HD 149026b, caution…”
• The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion (2007, background): “However, Fortney et al. (2006a) suggested that this planet might have a close-to-isothermal temperature profile on the dayside, which would wash out any absorption bands.”
• The Interior Structure, Composition, and Evolution of Giant Planets (2009, background): “…planets are expected to be metal rich (Jupiter and Saturn are 5-20% heavy elements) a mechanism that would otherwise lead to large radii could easily be canceled out by a large planetary core or a supersolar abundance of heavy elements in the H/He envelope in most planets (Fortney et al. 2006).”
• A TEMPERATURE AND ABUNDANCE RETRIEVAL METHOD FOR EXOPLANET ATMOSPHERES (2009, background): “…have been proposed in literature justifying the use of cloud-free models for these planets: finding weak effects of clouds on the P-T profile (Fortney et al. 2006 & 2008); fast sedimentation rates in radiative atmospheres (Barman et al. 2005); clouds forming too deep in the planetary…”
• H− Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18b (2018, background): “Strong irradiation combined with efficient optical absorbers in the atmosphere (such as TiO and VO in gas-phase) could cause an inversion layer in the temperature-pressure profile (Fortney et al. 2006, 2008; Burrows et al. 2008; Parmentier et al. 2015).”
• The Influence of Atmospheric Dynamics on the Infrared Spectra and Light Curves of Hot Jupiters (2006, methodology): “This is the same infrared radiative transfer scheme used in Fortney et al. (2005), Fortney et al. (2006) and M. S. Marley et al. (in prep.).”
• TRANSMISSION SPECTRA OF THREE-DIMENSIONAL HOT JUPITER MODEL ATMOSPHERES (2009, methodology): “Its planet-wide meanP-T profile is close to the boundary where CO and CH4 have equal abundances (Fortney et al. 2006b), given chemical equilibrium.”
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits (2006, methodology): “…et al. 2003; Burrows et al. 2003; Baraffe et al. 2005; Laughlin et al. 2005; Arras & Bildsten 2006 for calculations of structure and contraction of many planets) although one planet, HD 149026b, appears to be∼2/3 heavy elements by mass (Sato et al. 2005; Fortney et al. 2006; Ikoma et al. 2006).”
• The TRAPPIST survey of southern transiting planets. I. Thirty eclipses of the ultra-short period planet WASP-43 b (2012, background): “The red model features a dayside tem- perature inversion due to the strong optical opacity of TiO and VO gases (Hubeny et al. 2003, Fortney et al. 2006).”
• Optimal estimation retrievals of the atmospheric structure and composition of HD 189733b from secondary eclipse spectroscopy (2011, background): “…aecreasing temperature layer between 0.01 and 1 bar to model the HST /NICMOS measurements, making an adiabatic layer∼10 times thicker than our estimation, and theoretical models also considered adiabatic layers in the troposphere (Fortney et al.2006; Burrows et al. 2008; Showman et al. 2008).”
• A SYSTEMATIC RETRIEVAL ANALYSIS OF SECONDARY ECLIPSE SPECTRA. II. A UNIFORM ANALYSIS OF NINE PLANETS AND THEIR C TO O RATIOS (2013, methodology): “Furthermore, its likely high atmospheric metallicity and temperature make it a prime candidate for an inversion caused by gas-phase TiO and VO (Fortney et al. 2006).”
• On the Luminosity of Young Jupiters (2006, methodology): “The viability of giant planet formation via core accretion depends on physical processes happening earlier in the accretionary process (at smaller masses) than those processes that we have shown to be crucial for the luminosity of young planets of Jupiter’s mass and larger.”
• ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b (2008, unknown): “…that has been extensively used in 1D investigations of Titan, the giant planets, brown dwarfs, and exoplanets (e.g. McKay et al. 1989; Marley et al. 1996; Burrows et al. 1997; Marley et al. 1999, 2002; Fortney et al. 2005, 2006b,a; Fortney & Marley 2007; Fortney et al. 2008; Saumon & Marley 2008).”
• ATMOSPHERIC SULFUR PHOTOCHEMISTRY ON HOT JUPITERS (2009, background): “This level of heating approaches what Fortney et al (2006) and Burrows et al (2008) use in their most successful LTE spectral models.”
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets (2007, methodology): “Our group utilizes these opacities inmodels of ultracool dwarfs and extrasolar planets (e.g., Marley et al. 2002; Fortney et al. 2006; Saumon et al. 2007) and provides them to other members of the community.”
• SPITZER SECONDARY ECLIPSES OF THE DENSE, MODESTLY-IRRADIATED, GIANT EXOPLANET HAT-P- 20 b ?> USING PIXEL-LEVEL DECORRELATION (2014, background): “Figure 12 includes two solar metallicity model atmospheres (Burrows et al. 2006, 2007; Fortney et al. 2005, 2006a,b, 2008) that have minimal heat re-distribution.”
• MULTIWAVELENGTH CONSTRAINTS ON THE DAY–NIGHT CIRCULATION PATTERNS OF HD 189733b (2008, methodology): “…on the atmospheric dynamics of these planets will be applicable to smaller, core-dominated planets such as HD 149026b and GJ 436b (Butler et al. 2004; Sato et al. 2005; Fortney et al. 2006a; Gillon et al. 2007; Deming et al. 2007; Torres et al. 2007; Adams et al. 2008; Winn et al. 2008).”