Ground-Based Transit Spectroscopy of the Hot-Jupiter WASP-19b in the Near-Infrared

TL;DR

This study demonstrates ground-based near-infrared spectroscopy of exoplanet WASP-19b, revealing atmospheric composition and thermal structure consistent with theoretical models, and highlights the effectiveness of multi-object spectroscopy for exoplanet atmosphere characterization.

Contribution

First ground-based near-infrared transmission and emission spectra of WASP-19b using multi-object spectroscopy, constraining atmospheric properties and demonstrating the method's potential.

Findings

Transmission spectrum consistent with clear atmosphere models

Detected secondary eclipses with increasing significance at longer wavelengths

Emission spectrum matches a 2250 K isothermal atmospheric model

Abstract

We present ground-based measurements of the transmission and emission spectra of the hot-Jupiter WASP-19b in nine spectroscopic channels from 1.25 to 2.35 microns. The measurements are based on the combined analysis of time-series spectroscopy obtained during two complete transits and two complete secondary eclipses of the planet. The observations were performed with the MMIRS instrument on the Magellan II telescope using the technique of multi-object spectroscopy with wide slits. We compare the transmission and emission data to theoretical models to constrain the composition and thermal structure of the planet's atmosphere. Our measured transmission spectrum exhibits a scatter that corresponds to 1.3 scale heights of the planet's atmosphere, which is consistent with the size of spectral features predicted by theoretical models for a clear atmosphere. We detected the secondary eclipses of the planet at significances ranging from 2.2 to 14.4 sigma. The secondary eclipse depths, and the significances of the detections increase towards longer wavelengths. Our measured emission spectrum is consistent with a 2250 K effectively isothermal 1-D model for the planet's dayside atmosphere. This model also matches previously published photometric measurements from the Spitzer Space Telescope and ground-based telescopes. These results demonstrate the important role that ground-based observations using multi-object spectroscopy can play in constraining the properties of exoplanet atmospheres, and they also emphasize the need for high-precision measurements based on observations of multiple transits and eclipses.