MODELS OF NEPTUNE-MASS EXOPLANETS: EMERGENT FLUXES AND ALBEDOS

Journal Article · Wed Jan 20 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/709/1/149· OSTI ID:21392350

Spiegel, David S; Burrows, Adam; Ibgui, Laurent ^[1]; Hubeny, Ivan ^[2]

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1. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544 (United States)
2. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

There are now many known exoplanets with Msin i within a factor of 2 of Neptune's, including the transiting planets GJ 436b and HAT-P-11b. Planets in this mass range are different from their more massive cousins in several ways that are relevant to their radiative properties and thermal structures. By analogy with Neptune and Uranus, they are likely to have metal abundances that are an order of magnitude or more greater than those of larger, more massive planets. This increases their opacity, decreases Rayleigh scattering, and changes their equation of state. Furthermore, their smaller radii mean that fluxes from these planets are roughly an order of magnitude lower than those of otherwise identical gas giant planets. Here, we compute a range of plausible radiative equilibrium models of GJ 436b and HAT-P-11b. In addition, we explore the dependence of generic Neptune-mass planets on a range of physical properties, including their distance from their host stars, their metallicity, the spectral type of their stars, the redistribution of heat in their atmospheres, and the possible presence of additional optical opacity in their upper atmospheres.

• OSTI ID: 21392350
• Journal Information: Astrophysical Journal, Vol. 709, Issue 1; Other Information: DOI: 10.1088/0004-637X/709/1/149; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
ALBEDO
EQUATIONS OF STATE
MASS
METALS
NEPTUNE PLANET
OPACITY
PLANETARY ATMOSPHERES
RADIANT HEAT TRANSFER
RAYLEIGH SCATTERING
STARS
URANUS PLANET
ATMOSPHERES
COHERENT SCATTERING
ELEMENTS
ENERGY TRANSFER
EQUATIONS
HEAT TRANSFER
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLANETS
SCATTERING