| Abstract | Observing and studying the atmospheric absorption lines of the exoplanet is the most reliable method that could be used in determining the atmospheric characteristic. Among all the measurement modes the High-resolution molecular spectroscopy is one of the most successful methods to characterize exoplanet atmospheres and provides high-quality data[1]. The fundamental idea of this field is to study the climate, atomic/molecular signature, biosignature, and the formation history of an exoplanet by evaluating its emission spectra. In this paper, scientists analyze the high-resolution near-infrared emission spectra of an exoplanet (ultra-hot Jupiter) named WASP-33b using the IRD spectrograph on the Subaru telescope. After numerous treatments and examinations, scientists have concluded that they’ve detected the first Hydroxyl radical emission from its atmosphere which contributes information such as the chemical and thermochemical reaction in its atmosphere. The utilization of this technique could also bring potential advantages in future research of exoplanets’ atmosphere. |
| Spcific Question | The team focused on revealing OH and H2O emission signatures which are both chemical species that drive atmospheric chemistry. The specific question in this paper is whether or not scientists can analyze the emission signals detected by the IRD and filter out the noise and useless signals such as the sky emission lines and bad pixels, leaving the useful signal which contains valuable information. |
| Approach | The signal was received from 33 exposures covering the orbital phase of WASP-33 and was reduced in 70 spectral orders with an average signal/noise ratio of 140[1]. It is obvious that the signal contains a lot of noise and irrelevant information and the emission spectra of OH and H2O were embedded in those noise. To reduce all the useless signals scientists have introduced numerous treatments. Disentangle the telluric and stellar line via the detrending algorithm, SYSREM. Sky emission lines, bad pixels and pixels with less than 10% of the continuum were masked. The rest of the spectra are then cross-correlating with the OH and H2O spectrum templates. Cross-correlation is a measure of similarity between two series as a function of the displacement of one relative to the other. It is commonly used for searching a long signal for a shorter, known feature[2]. Using infrared because CO,OH,H2O.Constrain chemical abundance. |
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