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Register a new userThe 2~$mu$m spectrum of the auroral emission in the polar regions of Jupiter
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Lucyna Kedziora-Chudczer
Publication date
2017
fields
Physics
and research's language is
English
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We report observations of the high (R$sim$18000) and medium (R$sim$5900) resolution, near-infrared spectra of Jupiters polar regions with the GNIRS instrument at the Gemini North telescope. The observations correspond to the area of main auroral oval in the South and the main spot of the Io footprint in the North. We detected and assigned 18 emission lines of the H$_{3}^{+}$, 2$ u_{2}rightarrow 0$ overtone band in the region from 4800 to 4980 cm$^{-1}$ and 5 additional lines in the extended low-resolution spectrum. We use our new modelling scheme, ATMOF to remove telluric absorption bands of CO$_2$ that feature strongly in the 2 $mu$m region. The H${_2}$ 1-0 S(1), S(2) and S(3) emission lines are also detected in the observed spectral region. We found the rotational temperature and column density of H$_{3}^{+}$ emission at the peak intensity for both northern and southern auroral regions to be the same within the measurement errors (T$_{rot} sim950$K and N(H$_{3}^{+}$) $sim$ 4.5$times10^{16}$m$^{-2}$). The estimates of T$_{rot}$ from H$_{2}$ are consistent within much higher uncertainties with temperatures derived from H$_{3}^{+}$ emissions. We derived the profiles of the H$_{3}^{+}$ emissivity and ion density for both auroral regions providing the first such measurement for the emission associated with the main spot of the Io footprint. We also found a number of weaker lines in the high-resolution spectra that could be associated with emission from high excitation levels in neutral iron, which could be deposited in Jupiters atmosphere as a result of meteor ablation.
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The hot Jupiter WASP-79b is a prime target for exoplanet atmospheric characterization both now and in the future. Here we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. Given the temporal coverage of WASP-79bs secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1-1.7 $mu$m at 2.4$sigma$ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 $mu$m) and compare these observations to a grid of atmospheric forward models. Given the precision of our measurements, WASP-79bs infrared emission spectrum is consistent with theoretical spectra assuming equilibrium chemistry, enhanced abundances of H-, VO, or FeH, as well as clouds. The best match equilibrium model suggests WASP-79bs dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H- opacity provide the best match to WASP-79bs emission spectrum near 1.58 $mu$m. However, models featuring high-temperature cloud species - formed via vigorous vertical mixing and low sedimentation efficiencies - with little day-to-night energy transport also match WASP-79bs emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79bs dayside emission, further observations will be necessary to constrain WASP-79bs dayside atmospheric properties.
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