Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b

TL;DR

This study combines transit timing variation and transmission spectroscopy to analyze the atmosphere and possible additional planets of the hot Neptune GJ3470b, revealing a haze-rich atmosphere and constraining system architecture.

Contribution

It provides the first combined TTV and transmission spectroscopy analysis of GJ3470b, offering new insights into its atmospheric composition and system dynamics.

Findings

Excludes hot Jupiters with periods less than 10 days

Favors a haze-dominated atmosphere with high-altitude particles

Suggests presence of methane in GJ3470b's atmosphere

Abstract

GJ3470b is a hot Neptune exoplanet orbiting an M dwarf and the first sub-Jovian planet to exhibit Rayleigh scattering. We present transit timing variation (TTV) and transmission spectroscopy analyses of multi-wavelength optical photometry from 2.4-m and 0.5-m telescopes at the Thai National Observatory, and the 0.6-m PROMPT-8 telescope in Chile. Our TTV analysis allows us to place an upper mass limit for a second planet in the system. The presence of a hot Jupiter with a period of less than 10 days or a planet with an orbital period between 2.5 and 4.0 days are excluded. Combined optical and near-infrared transmission spectroscopy favour an H/He dominated haze (mean molecular weight 1.08$\pm$0.20) with high particle abundance at high altitude. We also argue that previous near-infrared data favour the presence of methane in the atmosphere of GJ3470b.