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Register a new userExoplanet-atmospheres at high spectral resolution: A CRIRES survey of hot-Jupiters
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Recently, we presented the detection of carbon monoxide in the transmission spectrum of extrasolar planet HD209458b, using CRIRES, the Cryogenic high-resolution Infrared Echelle Spectrograph at ESOs Very Large Telescope (VLT). The high spectral resolution observations (R=100,000) provide a wealth of information on the planets orbit, mass, composition, and even on its atmospheric dynamics. The new observational strategy and data analysis techniques open up a whole world of opportunities. We therefore started an ESO large program using CRIRES to explore these, targeting both transiting and non-transiting planets in carbon monoxide, water vapour, and methane. Observations of the latter molecule will also serve as a test-bed for METIS, the proposed mid-infrared imager and spectrograph for the European Extremely Large Telescope.
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We provide a brief review of many aspects of the planetary physics of hot Jupiters. Our aim is to cover most of the major areas of current study while providing the reader with additional references for more detailed follow-up. We first discuss giant planet formation and subsequent orbital evolution via disk-driven torques or dynamical interactions. More than one formation pathway is needed to understand the population. Next, we examine our current understanding of the evolutionary history and current interior structure of the planets, where we focus on bulk composition as well as viable models to explain the inflated radii of the population. Finally we discuss aspects of their atmospheres in the context of observations and 1D and 3D models, including atmospheric structure and escape, spectroscopic signatures, and complex atmospheric circulation. The major opacity sources in these atmospheres, including alkali metals, water vapor, and others, are discussed. We discuss physics that control the 3D atmospheric circulation and day-to-night temperature structures. We conclude by suggesting important future work for still-open questions.
In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey (QES). Qatar-8b is a hot Saturn, with Mpl = 0.37 Mjup and Rpl = 1.3 Rjup, orbiting a solar-like star every Porb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of Mpl = 1.2 Mjup and a radius of Rpl = 1 Rjup, in a Porb = 1.5 days orbit around a low mass, Mstar = 0.7 Msun, mid-K main-sequence star. Finally, Qatar-10b is a hot, Teq ~ 2000 K, sub-Jupiter mass planet, Mpl = 0.7 Mjup, with a radius of Rpl = 1.54 Rjup and an orbital period of Porb = 1.6 days, placing it on the edge of the sub-Jupiter desert.
[Abridged] Recently, there have been a series of detections of molecules in the atmospheres of extrasolar planets using high spectral resolution (R~100,000) observations, mostly using the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES) on the Very Large Telescope. These measurements are able to resolve molecular bands into individual absorption lines. Observing many lines simultaneously as their Doppler shift changes with time allows the detection of specific molecules in the atmosphere of the exoplanet. We performed simulations of high-resolution CRIRES observations of a planets thermal emission and transit between 1-5 micron and performed a cross-correlation analysis on these results to assess how well the planet signal can be extracted. We also simulated day-side and night-side spectra at high spectral resolution for planets with and without a day-side temperature inversion, based on the cases of HD 189733b and HD 209458b. Several small wavelength regions in the L-band promise to yield cross-correlation signals from the thermal emission of hot Jupiters that can exceed those of the current detections by up to a factor of 2-3 for the same integration time. For transit observations, the H-band is also attractive, with the H, K, and L-band giving cross-correlation signals of similar strength. High-resolution night-side spectra of hot Jupiters can give cross-correlation signals as high as the day-side, or even higher. We show that there are many new possibilities for high-resolution observations of exoplanet atmospheres that have expected planet signals at least as high as those already detected. Hence, high-resolution observations at well-chosen wavelengths and at different phases can improve our knowledge about hot Jupiter atmospheres significantly, already with currently available instrumentation.
Hot Jupiter atmospheres exhibit fast, weakly-ionized winds. The interaction of these winds with the planetary magnetic field generates drag on the winds and leads to ohmic dissipation of the induced electric currents. We study the magnitude of ohmic dissipation in representative, three-dimensional atmospheric circulation models of the hot Jupiter HD 209458b. We find that ohmic dissipation can reach or exceed 1% of the stellar insolation power in the deepest atmospheric layers, in models with and without dragged winds. Such power, dissipated in the deep atmosphere, appears sufficient to slow down planetary contraction and explain the typically inflated radii of hot Jupiters. This atmospheric scenario does not require a top insulating layer or radial currents that penetrate deep in the planetary interior. Circulation in the deepest atmospheric layers may actually be driven by spatially non-uniform ohmic dissipation. A consistent treatment of magnetic drag and ohmic dissipation is required to further elucidate the consequences of magnetic effects for the atmospheres and the contracting interiors of hot Jupiters.
Aims: We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution, and elaborate on existing interpretations of the optical transmission spectrum observed with HST/STIS and WFC3. Methods: We use the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We inject models assuming chemical and hydrostatic equilibrium with varying temperature and composition to enable model comparison, and employ two bootstrap methods to test the robustness of our detections. Results: We detect neutral Mg, Na, Ca, Cr, Fe, Ni and V, which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO$_2$, VO$_2$ and TiS, which could be important absorbers at optical and NIR wavelengths in hot Jupiter atmospheres, but for which accurate line-list data is currently not available. We find no evidence for absorption by SH, and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the NUV with HST/STIS. The Na D lines are significantly broadened and show a difference in their respective depths of 15 scale heights, which is not expected from isothermal hydrostatic theory.
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