Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars I. Carbon, Nitrogen, and Oxygen

Lodders, K.; Fegley, B.

doi:10.1006/icar.2001.6740

Cited by 370 publications

(418 citation statements)

References 56 publications

(82 reference statements)

Supporting

Mentioning

401

Contrasting

Order By: Relevance

“…We use the elemental abundance data of Lodders (2003) and compute chemical equilibrium compositions following Fegley & Lodders (1994) and Lodders & Fegley (2002). In addition, we maintain a large and constantly updated opacity database.…”

Section: Atmosphere Modelsmentioning

confidence: 99%

Young Jupiters are faint: new models of the early evolution of giant planets

Fortney¹,

Marley

Hubickyj

et al. 2005

Astron Nachr

View full text Add to dashboard Cite

Abstract.Here we show preliminary calculations of the cooling and contraction of a 2 MJ planet. These calculations, which are being extended to 1-10 MJ, differ from other published "cooling tracks" in that they include a core accretion-gas capture formation scenario, the leading theory for the formation of gas giant planets. We find that the initial post-accretionary intrinsic luminosity of the planet is ∼3 times less than previously published models which use arbitrary initial conditions. These differences last a few tens of millions of years. Young giant planets are intrinsically fainter than has been previously appreciated. We also discuss how uncertainties in atmospheric chemistry and the duration of the formation time of giant planets lead to challenges in deriving planetary physical properties from comparison with tabulated model values.

show abstract

Section: Atmosphere Modelsmentioning

confidence: 99%

Young Jupiters are faint: new models of the early evolution of giant planets

Fortney¹,

Marley

Hubickyj

et al. 2005

Astron Nachr

View full text Add to dashboard Cite

show abstract

“…An increased methane mixing ratio of 10 6 would result in a higher blackbody continuum, thus requiring a CO 2 mixing ratio 10 3 in order to fit the flux constraint at 4.5 m (Figure 3). However, thermochemical equilibrium and photochemical models predict a CO 2 mixing ratio of ~10 7in hydrogen-dominated atmospheres at solar abundance (~10 5 for 30 times solar metallicities) 19,20 .We also explored other possibilities to explain the observations. A temperature inversion does not fit the data well, assuming thermochemical equilibrium, because H 2 O and CH 4 would emit much more strongly than we observe in the 5.8-and 8.0-m channels, respectively.…”

mentioning

confidence: 98%

Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b

Stevenson

Harrington

Nymeyer

et al. 2010

Nature

281

422

View full text Add to dashboard Cite

The nearby extrasolar planet GJ 436b-which has been labelled as a 'hot Neptune'-reveals itself by the dimming of light as it crosses in front of and behind its parent star as seen from Earth. Respectively known as the primary transit and secondary eclipse, the former constrains the planet's radius and mass 1,2 , and the latter constrains the planet's temperature 3,4 and, with measurements at multiple wavelengths, its atmospheric composition. Previous work 5 using transmission spectroscopy failed to detect the 1.4-m water vapour band, leaving the planet's atmospheric composition poorly constrained. Here we report the detection of planetary thermal emission from the dayside of GJ 436b at multiple infrared wavelengths during the secondary eclipse.The best-fit compositional models contain a high CO abundance and a substantial methane (CH 4 ) deficiency relative to thermochemical equilibrium models 6 for the predicted hydrogen-dominated atmosphere 7,8 . Moreover, we report the presence of some H 2 O and traces of CO 2 . Because CH 4 is expected to be the dominant carbonbearing species, disequilibrium processes such as vertical mixing 9 and polymerization of methane 10 into substances such as ethylene may be required to explain the hot Neptune's small CH 4 -to-CO ratio, which is at least 10 5 times smaller than predicted 6 .Using the Spitzer Space Telescope 11 , the Spitzer Exoplanet Target of Opportunity program observed multiple secondary eclipses at wavelengths of 3. 6, 4.5, 5.8, 8.0 Figure 1 shows the observed secondary eclipses with best-fit models, and Table 1 presents the relevant eclipse parameters.The phase of secondary eclipse imposes a tight constraint on the planet"s eccentricity, e, and argument of periapsis, . Using the secondary eclipse times listed in Table 1, in addition to published transit 16 and radial-velocity data 17 , a single-planet Our broadband observations constrain a one-dimensional atmospheric model, using a new temperature and abundance retrieval method 18 . This method searches over a wide parameter space using a functional form for the pressure-temperature profile (based on prior "hot Jupiter" and Solar System studies), a grid of abundance combinations, and energy conservation. We calculated ~10 6 models, which considered both inversion and noninversion temperature profiles and abundances that varied over several orders of magnitude Publisher: NPG; Journal: Nature: Nature; Article Type: Physics letter DOI: 10.1038/nature09013Page 3 of 42per constituent. Figure 2 shows two representative models (the red and blue lines) that fit the data, and and, to a lesser extent, CO, and possibly CO 2 . In a reduced, hydrogen-dominated atmosphere at ~700 K, CH 4 is thermochemically favoured to be the main carbon-bearing molecule. Assuming solar abundances for the elements and the pressure-temperature profile shown in Supplementary Fig. 5, chemical equilibrium predicts 6 a CH 4 -to-H 2 mixing ratio of 7 × 10 4 and an H 2 O mixing ratio of 2 × 10 3 . However, the strong planetary emission at 3.6 m...

show abstract

“…Thermochemical equilibrium computations indicate that several compounds may be useful to establish temperature or pressure scales for giant planets, Brown Dwarfs or dwarf star atmospheres (Lodders and Fegley 2002). For giant planets and warm methane dwarfs, such as Gl 229B, the deep atmospheric abundance of ethane is a diagnostic temperature probe.…”

Section: Status Of Current Databases For Hot Temperaturesmentioning

confidence: 99%

Spectroscopy of planetary atmospheres in our Galaxy

Tinetti

Encrenaz

Coustenis

2013

Astron Astrophys Rev

128

111

View full text Add to dashboard Cite

About 20 years after the discovery of the first extrasolar planet, the number of planets known has grown by three orders of magnitude, and continues to increase at neck breaking pace. For most of these planets we have little information, except for the fact that they exist and possess an address in our Galaxy. For about one third of them, we know how much they weigh, their size and their orbital parameters. For less than 20, we start to have some clues about their atmospheric temperature and composition. How do we make progress from here?We are still far from the completion of a hypothetical Hertzsprung-Russell diagram for planets comparable to what we have for stars, and today we do not even know whether such classification will ever be possible or even meaningful for planetary objects. But one thing is clear: planetary parameters such as mass, radius and temperature alone do not explain the diversity revealed by current observations. The chemical composition of these planets is needed to trace back their formation history and evolution, as happened for the planets in our Solar System. As in situ measurements are and will remain off-limits for exoplanets, to study their chemical composition we will have to rely on remote sensing spectroscopic observations of their gaseous envelopes.

show abstract

Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars I. Carbon, Nitrogen, and Oxygen

Cited by 370 publications

References 56 publications

Young Jupiters are faint: new models of the early evolution of giant planets

Young Jupiters are faint: new models of the early evolution of giant planets

Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b

Spectroscopy of planetary atmospheres in our Galaxy

Contact Info

Product

Resources

About