Doppler Imaging of Exoplanets and Brown Dwarfs

TL;DR

Doppler Imaging enables detailed 2D mapping of exoplanets and brown dwarfs' atmospheres, with current and future telescopes expanding the range of observable targets for atmospheric and magnetic studies.

Contribution

This paper assesses the potential of Doppler Imaging for substellar objects using current and future telescopes, including a compilation of relevant observational data.

Findings

Several bright objects are currently accessible for Doppler Imaging.

Giant ground-based telescopes will enable imaging of many brown dwarfs and some exoplanets.

Current measurements are biased toward early-type objects, highlighting the need for more data on later types.

Abstract

Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in un- precedented detail. I present the first quantitative assessment of the prospects for Doppler Imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (v sin i) for brown dwarfs and exoplanets. Several bright objects are already accessible to Doppler Imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler Imaging will become feasible for many dozens of brown dwarfs and for the few brightest directly imaged extrasolar planets (such as beta Pic b). The present set of measurements of P, v sin i, and variability are incomplete for many objects, and the sample is strongly biased toward early-type objects (< L5). Thus, surveys to measure these quantities for later-type objects will be especially helpful in expanding the sample of candidates for global weather monitoring via Doppler Imaging.