Day 460

Friday.

1307.1133
Detection of water absorption in the dayside atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns
Birkby et al

Absorption features in the dayside spectrum of hot Jupiter.  Trace radial velocity shift of the water features in the planet's dayside atmosphere during 5 hours of 2.2 day orbit as it approached secondary eclipse.  Detect signal (despite telluric contamination) at the expected combination of systemic velocity (Vsys=-3pm5km/s) and planet orbital velocity (Kp=154pm13 km/s) and determine a H2O line contrast ratio of (1.3pm0.2)e-3 with respect to the stellar continuum.  Find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although a marginal increase in the significance of detection with inclusion of CO2 in the template spectrum.  Demonstrates that ground-based, high-resolution spectroscopy is suited to finding not must simple molecules like CO, but also to more complex molecules like H2O even in highly telluric contaminated regions of the Earth's transmission spectrum.  It is a powerful tool that can be used for conducting an immediate census of the carbon- and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.