"For those who are living on a blue tiny lonely planet, curiosity is the key for understanding their universe" Abstract "In this project we investigate the transmission spectrum of the hot JupiterHD 189733b using ground-based data from the High Accuracy Radial Velocity PlanetSearcher (HARPS) spectrograph. At a resolution of about R∼120000, we searchfor the extra absorption due to the planetary atmosphere at the location of thesodium D lines (588.99 nm and 589.59 nm). The ground-based detection of sodiumin HD 189733b was claimed for the first time by Redfield et al. (2008) and was laterrevised by Jensen et al. (2011). However, their detection is not very robust dueto imperfection in their reduction procedure. We analyse the ground-based trans-mission spectrum of this planet, with a higher resolution set of data and with two diff erent methods.In our analysis we use two approaches based on transmission spectroscopy. First, weobtain the excess in the depth of the transit light curve (light curve approach) andthen, we obtain the transmission spectrum by diving the average of the in-transitspectra by the average of the out-of-transit spectra (line depth approach).Although the first approach has already been successful for HD 209458b (Snellenet al., 2008), it failed in the case of this planetary system. However, with thesecond approach we detect excess absorption features at the location of sodium Dlines with an average absorption depth of (1.06±0.24) ×10−2 at the 4.5σ confi-dence level. The result from this approach, closely resembles the results obtained byJensen et al. (2011) and Redfield et al. (2008). In all of these attempts, the ground-based detection of sodium in HD 189733b is still not very robust, possibly due toslight misalignments and systematic errors. Finally, by comparing our result withthe previous work and also by comparison of the first and second approaches witheach other, we discuss the importance of selecting the correct analysis techniquebased on the nature of the spectral lines and type of observations and instruments."
Posted on: Sat, 10 Aug 2013 03:43:46 +0000
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