Abstract
Context: Since the first exoplanetary atmosphere detection using the Hubble Space Telescope, characterization of exoplanet atmospheres from the ground have been playing an increasingly important role in the analysis of such atmospheres thanks to the enhancement of telluric correction techniques. At present, several species have been discovered in the atmosphere of HD 209458b, all of them consistent with theoretical models. Aims: Data acquired using the High Dispersion Spectrograph on the Subaru telescope are re-analysed. We expect to discover new species in the atmosphere of the exoplanet HD 209458b. In addition to shed light on the atmospheric composition, we will derive the radial extension of the absorbents present in the atmosphere of the exoplanet. Methods: We present an alternative method to correct the telluric effects through the analysis of variations in spectral lines with the airmass. To search absorptions due to an exoplanetary atmosphere we implemented an algorithm to automatically search for all the features presenting an atmospheric signature in the transmission spectrum and through the wavelength range in the data. In order to estimate uncertainties we perform a bootstrapping analysis. Results: Absorption excess due to the transitions of Calcium at 6162.17A and 6493.78A, Scandium at 5526.79A, Hydrogen at 6562.8A and Sodium doublet are detected in the transmission spectrum at a level of -0.079+-0.012%, -0.138+-0.013%, -0.059+-0.012%, -0.123+-0.012%, -0.071+-0.016% using pass-bands of 0.5A, 0.4A, 0.5A, 1.1A and 0.6A, respectively. Conclusions: Models predict strong absorption in the Sodium resonance Doublet which was previously detected, also in this analysis. However, this is the first report of Calcium and possibly Scandium in HD 209458b, including the possible ground-based detection of Hydrogen. ... (continues)
Highlights
Since the first detection of an extrasolar planet (Mayor & Queloz 1995) the radial-velocity and transit method have allowed the measurement of dynamics and bulk properties of hundreds of exoplanets
Absorption excess due to the transitions of calcium at 6162.17 Å and 6493.78 Å, scandium at 5526.79 Å, hydrogen at 6562.8 Å, and the sodium doublet are detected in the transmission spectrum at a level of −0.079 ± 0.012%, −0.138 ± 0.013%, −0.059 ± 0.012%, −0.123 ± 0.012%, −0.071 ± 0.016% using pass-bands of 0.5 Å, 0.4 Å, 0.5 Å, 1.1 Å, and 0.6 Å, respectively
From R2008, and Jensen et al (2011, 2012) we note that features in the transmission spectrum fall within stellar line profiles because even if spectral lines are broader in atmospheres such as HD 209458b the strongest absorption occurs at the core
Summary
Since the first detection of an extrasolar planet (Mayor & Queloz 1995) the radial-velocity and transit method have allowed the measurement of dynamics and bulk properties of hundreds of exoplanets. The purpose of present study was to perform a so-called blind search in the whole transmission spectrum of HD 209458b to automatically detect strong and missed absorption produced in the exoplanetary atmosphere for every strong transition reported in databases. We independently and automatically analysed the region around each of the transitions indexed in The Interactive Database of Spectral Standard Star Atlases (Lobel 2008) This database lists the line parameters, including rest wavelength, oscillator strength (gi fi j), expected line depth, and responsible element for telluric and stellar transitions for a subset of template standard stars. For HD 209458 (G0 V) we used the solar spectrum template because it is the closest spectral type Using this database limited our study to transitions present in the host star, i.e. we were restricted to exoplanet elements that are present in the parent star atmosphere
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