HR8799b, c, and d Spectral and Photometric Models and New "Thick-Cloud" Models
Taken from Madhusudhan, Burrows, and Currie (2011)

Description: The tar files below are a collection of spectral models found and described in the paper submitted to the Astrophysical Journal entitled Model atmospheres for massive gas giants with thick clouds: Application to the HR~8799 planets" by N. Madhusudhan, A. Burrows, and T. Currie (2011). We have generated an extensive new suite of massive giant planet atmosphere models and used it to obtain fits to photometric data for the planets HR~8799b, c, and d. We consider a wide range of cloudy and cloud-free models. The cloudy models incorporate different geometrical and optical thicknesses, modal particle sizes, and metallicities. For each planet and set of cloud parameters, we explore grids in gravity and effective temperature, with which we determine constraints on the planet's mass and age. Our new models yield statistically significant fits to the data, and conclusively confirm that the HR 8799 planets have much thicker clouds than those required to explain data for typical L and T dwarfs. Both models with 1) physically thick forsterite clouds and a 60-$\mu m$ modal particle size and 2) clouds made of 1 $\mu m$-sized pure iron droplets and 1\% supersaturation fit the data. The range of best-estimated masses for HR 8799b, HR 8799c, and HR 8799d conservatively span 2--12 M$_{J}$, 7--13 M$_{J}$, and 3--11 M$_{J}$, respectively and imply coeval ages between $\sim$20 and $\sim$150 Myr, consistent with previously reported stellar age. The best-fit temperatures and gravities are slightly lower than values obtained by Currie et al. (2011) using even thicker cloud models. Finally, we use these models to predict the near-to-mid IR colors of soon-to-be imaged planets. Our models predict that planet-mass objects follow a locus in some near-to-mid IR color-magnitude diagrams that is clearly separable from the standard L/T dwarf locus for field brown dwarfs.



Madhusudhan, Burrows, and Currie paper include models with clouds of various geometrical thicknesses, (composed of either forsterite or iron), cloud-free models, and non-equilibrium models. Should you employ these theoretical models in a talk, publication, proposal, or any document, we would appreciate it if you would refer to this paper. Feel free to contact Adam Burrows (burrows@astro.princeton.edu) if you have questions or requests.

Below you will find models used in our HR 8799 study, as well as a suite of new models for "thick" clouds such as those that were necessary to fit the HR8799 "planets," but for a wider range of effective temperatures and gravities:

Nomenclature for cloudy models:


The filename contains information on the cloud-type, particle size, effective temperature, cloud composition, metallicity, and gravity, in that order. The first letter in the filename denotes the cloud type: 'A','AE','E', or 'AEE', corresponding to the four cloud types with different physical extents, as described in the paper. For example: "A100.1000.cloud.3solar.g4.0.21" implies an A-type cloud model, with 100 micron modal particle size, Teff = 1000 K, Fosterite composition ('cloud' by default implies forsterite clouds), metallicity = 3 x solar, and log10(g) = 4.0. The ".21" at the end is for file tracking purposes and has no physical meaning. For iron clouds, 'cloud' in the filename is replaced by 'Fecloud'. If no particle size or metallicity is indicated, they are assumed to be 30 micron particle size and solar metallicity, respectively. For example: "A.1000.cloud.g4.0.21" or "A60.1200.cloud.g4.25.21".

Nomenclature for clear (cloud-free) models:
For cloud-free models in chemical equilibrium, the filename starts with 'T', followed by the effective temperature and gravity. For example, 'T1100_g45.clr' implies a clear model with Teff = 1100 K and log10(g) = 4.5. The '.clr' file extension signifies a 'clear' atmosphere model. For models with non-equilibrium chemistry, the filename also contains information on the eddy diffusion. For example, 'T1100_g45_d6f2.clr' implies a clear model with Teff = 1100 K, log10(g) = 4.5, and eddy diffusion coefficient (K_zz) = 1.0E+6 cm^2/s. The 'f2' indicates efficient transport rate ('fN' can be 'f0', 'f1', or 'f2', 'f2' being the highest rate).

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