The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b

Ballester, G. E.; Sing, David K.; Herbert, F.

doi:10.1038/nature05525

Cited by 145 publications

(126 citation statements)

References 13 publications

Supporting

Mentioning

111

Contrasting

Order By: Relevance

“…The STIS transit spectrum details of HD209458b presented here is found in Sing et al (2008a,b), , and Désert et al (2008) and builds off of the previous work of Ballester et al (2007), Knutson et al (2007), and Charbonneau et al (2002). In our re-analysis we find that the spectrum shows:…”

Section: Hd209458bsupporting

confidence: 88%

Absorption Spectra of the Prototype Hot-Jupiters: determination of atmospheric constituents and structure

et al. 2008

Self Cite

View full text Add to dashboard Cite

Abstract. The two prototype hot-Jupiter exoplanets HD209458b and HD189733b are currently offering an unprecedented view of their atmospheres. As discussed here, primary transit transmission spectra provide the opportunity to identify specific atomic and molecular species, determine their abundances, and recover temperature-pressure-altitude information. We present a reanalysis of existing HST/STIS data on HD209458b, providing a complete optical transmission spectrum. Analysis of this spectrum have revealed: (1) the planetary abundance of sodium which is ∼2X solar (2) a depletion of sodium at high altitudes due to condensation or ionization (3) Rayleigh scattering by H 2 (3) a high temperature at pressures of 10's mbar consistent with the dayside inversion (4) a separate high-altitude hot temperature from the planet's thermosphere and (5) likely absorption by TiO/VO. While HD209458b and HD189733b are currently the best candidates for these studies, another ∼10 exoplanets are good targets with today's instruments for future transmission-based atmospheric detections.

show abstract

Section: Hd209458bsupporting

confidence: 88%

Absorption Spectra of the Prototype Hot-Jupiters: determination of atmospheric constituents and structure

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…We found layers at temperatures clearly below the NaI condensation temperature showing that sodium condensation has to take place at these levels, followed by a temperature rise at higher altitudes up to about 2500 K. This rise is likely the signature of the thermosphere needed to link the cool lower to the hot upper atmosphere, as suggested by the observations of atmospheric escape (Vidal-Madjar et al 2003, 2004Linsky et al 2010), observations of high temperatures (Ballester et al 2007), and models of the escape mechanism (Lecavelier des Yelle 2004;Tian et al 2005;Yelle 2006;Muñoz 2007;Murray-Clay et al 2009). …”

Section: Resultsmentioning

confidence: 55%

“…Of particular interest are Hubble Space Telescope (HST) observations of HD 209458 b during primary transit, which yielded the detection of NaI (Charbonneau et al 2002), as well as HI, OI, and CII (Vidal-Madjar et al 2003, 2004, HI (Ballester et al 2007), Rayleigh scattering by H 2 (Lecavelier des , along with upper limits on the presence of TiO and VO (Désert et al 2008) and recently confirmation of CII and detection of SiIII (Linsky et al 2010) and even possibly SiIV (Schlawin et al 2010). HD 189733 b is the second transiting planet for which HST observations yielded information on the atmospheric transmission spectrum.…”

Section: Introductionmentioning

confidence: 99%

The upper atmosphere of the exoplanet HD 209458 b revealed by the sodium D lines

Vidal‐Madjar

Sing

Étangs

et al. 2011

A&A

View full text Add to dashboard Cite

A complete reassessment of the Hubble Space Telescope (HST) observations of the transits of the extrasolar planet HD 209458 b has provided a transmission spectrum of the atmosphere over a wide range of wavelengths. Analysis of the NaI absorption line profile has already shown that the sodium abundance has to drop by at least a factor of ten above a critical altitude. Here we analyze the profile in the deep core of the NaI doublet line from HST and high-resolution ground-based spectra to further constrain the vertical structure of the HD 209458 b atmosphere. With a wavelength-dependent cross section that spans more than 5 orders of magnitude, we use the absorption signature of the NaI doublet as an atmospheric probe. The NaI transmission features are shown to sample the atmosphere of HD 209458 b over an altitude range of more than 6500 km, corresponding to a pressure range of 14 scale heights spanning 1 millibar to 10 −9 bar pressures. By comparing the observations with a multi-layer model in which temperature is a free parameter at the resolution of the atmospheric scale height, we constrain the temperature vertical profile and variations in the Na abundance in the upper part of the atmosphere of HD 209458 b. We find a rise in temperature above the drop in sodium abundance at the 3 mbar level. We also identify an isothermal atmospheric layer at 1500 ± 100 K spanning almost 6 scale heights in altitude, from 10 −5 to 10 −7 bar. Above this layer, the temperature rises again to 2500 +1500 −1000 K at ∼10 −9 bar, indicating the presence of a thermosphere. The resulting temperature-pressure (T-P) profile agrees with the Na condensation scenario at the 3 mbar level, with a possible signature of sodium ionization at higher altitudes, near the 3×10 −5 bar level. Our T-P profile is found to be in good agreement with the profiles obtained with aeronomical models including hydrodynamic escape.

show abstract

“…More recently, additional detections have been reported, including HI from recombination via the Balmer jump (Ballester et al 2007), H 2 the main gaseous content via Rayleigh scattering (Sing et al 2008a,b;Lecavelier des Etangs et al 2008b), and TiO/VO (Désert et al 2008). The possible signature from H 2 O in HD 209458b (Barman 2007) is now strongly questioned by new HST (the Hubble Space Telescope) and Spitzer (a Space Telescope, studying the universe in infrared) observations, revealing on the contrary the presence of high-altitude haze as well as CO in the atmosphere of HD 189733b (Ehrenreich et al 2007; Lecavelier des Sing et al 2009;Désert et al 2009Désert et al , 2010.…”

Section: Introductionmentioning

confidence: 99%

The Earth as an extrasolar transiting planet

Vidal‐Madjar

Arnold

Ehrenreich

et al. 2010

A&A

View full text Add to dashboard Cite

Context. An important goal within the quest for detecting an Earth-like extrasolar planet, will be to identify atmospheric gaseous bio-signatures. Aims. Observations of the light transmitted through the Earth's atmosphere, as for an extrasolar planet, will be the first important step for future comparisons. We have completed observations of the Earth during a lunar eclipse, a unique situation similar to that of a transiting planet. We aim at showing what species could be detected in its atmosphere at optical wavelengths, where a lot of photons are available in the masked stellar light. Methods. We present observations of the 2008 August 16 Moon eclipse performed with the SOPHIE spectrograph at the Observatoire de Haute-Provence (France). Locating the spectrograph's fibers in the penumbra of the eclipse, the Moon irradiance is then a mix of direct, unabsorbed Sun light and solar light that has passed through the Earth's atmosphere. This mixture essentially reproduces what is recorded during the transit of an extrasolar planet. Results. We report here the clear detection of several Earth atmospheric compounds in the transmission spectra, such as ozone, molecular oxygen, and neutral sodium as well as molecular nitrogen and oxygen through the Rayleigh signature. Moreover, we present a method that allows us to derive the thickness of the atmosphere versus the wavelength for penumbra eclipse observations. We quantitatively evaluate the altitude at which the atmosphere becomes transparent for important species like molecular oxygen and ozone, two species thought to be tightly linked to the presence of life. Conclusions. The molecular detections presented here are an encouraging first attempt, necessary to better prepare for the future of extremely-large telescopes and transiting Earth-like planets. Instruments like SOPHIE will be mandatory when characterizing the atmospheres of transiting Earth-like planets from the ground and searching for bio-marker signatures.

show abstract

The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b

Cited by 145 publications

References 13 publications

Absorption Spectra of the Prototype Hot-Jupiters: determination of atmospheric constituents and structure

Absorption Spectra of the Prototype Hot-Jupiters: determination of atmospheric constituents and structure

The upper atmosphere of the exoplanet HD 209458 b revealed by the sodium D lines

The Earth as an extrasolar transiting planet

Contact Info

Product

Resources

About