The Dynamics-Based Approach to Studying Terrestrial Exoplanets

TL;DR

This paper argues that dynamics-based methods like radial velocity and transit photometry are sufficient for studying terrestrial exoplanets, especially around M-dwarfs, and can be more practical than extreme imaging techniques.

Contribution

It advocates for focusing resources on refining existing dynamics-based detection and characterization methods instead of relying solely on advanced imaging technologies.

Findings

Dynamics-based methods dominate exoplanet detection over the past decade.

M-dwarfs offer promising targets due to their close habitable zones and frequent transits.

Dedicated ground surveys of nearby M-dwarfs could discover and characterize habitable planets.

Abstract

One of the great quests of astronomy is to obtain the spectrum of a terrestrial planet orbiting within the habitable zone of its star, and the dominant challenge in doing so is to isolate the light of the planet from that of the star. Dynamics-based methods separate these signals temporally, whereas imaging techniques do so spatially. In light of the overwhelming dominance of dynamics-based methods over the past decade, we challenge the notion that spectra of terrestrial planets necessarily require extreme imaging methods. We advocate that some resources be committed to refining the proven technologies of radial-velocity measurements, transit photometry, and occultation spectroscopy (i.e. emergent infrared spectra obtained at secondary eclipse). We see a particularly attractive opportunity in M-dwarfs, for which the habitable zone is close to the star, increasing the probability and frequency of transits, and the amplitude of the induced radial-velocity variation. Such planets could be discovered by a dedicated ground-based transit survey of the 10,000 nearest M-dwarfs. The favorable planet-star contrast ratio would make these planets ideal targets for the study of their atmospheres with the technique of occultation spectroscopy.