Characterizing the atmospheres of transiting rocky planets around late type dwarfs

TL;DR

This paper explores the potential of upcoming extremely large telescopes to detect atmospheric biomarkers on Earth-like planets orbiting late-type dwarfs, indicating possible signs of life within feasible observation times.

Contribution

It demonstrates that future telescopes could effectively characterize atmospheres of rocky exoplanets around cool stars, highlighting the detectability of key bio-markers like water, oxygen, and methane.

Findings

Detection of atmospheric biomarkers possible within a hundred hours for Earth-like planets.

Detection time reduces to a few hours for super-Earths with twice Earth's radius.

Spectral features of key molecules can be simultaneously observed in the near-infrared range.

Abstract

Visible and near-infrared spectra of transiting hot Jupiter planets have recently been observed, revealing some of the atmospheric constituents of their atmospheres. In the near future, it is probable that primary and secondary eclipse observations of Earth-like rocky planets will also be achieved. The characterization of the Earth's transmission spectrum has shown that both major and trace atmospheric constituents may present strong absorption features, including important bio-markers such as water, oxygen and methane. Our simulations using a recently published empirical Earth's transmission spectrum, and the stellar spectra for a variety of stellar types, indicate that the new generation of extremely large telescopes, such as the proposed 42-meter European Extremely Large Telescope(E-ELT), could be capable of retrieving the transmission spectrum of an Earth-like planet around very cool stars and brown dwarfs (Teff < 3100 K). For a twin of Earth around a star with Teff around 3100 K (M4), for example, the spectral features of water vapor, methane, carbon dioxide, and oxygen in the wavelength range between 0.9 and 2.4 micron can simultaneously be detected within a hundred hours of observing time, or even less for a late-M star. Such detection would constitute a proof for the existence of life in that planet. The detection time can be reduced to a few hours for a super-Earth type of planet with twice the Earth's radius.