The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES): driving science cases and expected outcomes

TL;DR

SCALES is a high-contrast integral field spectrograph for Keck Observatory designed to detect and characterize colder exoplanets and enable broader astronomical studies, with expected first light around 2025.

Contribution

This paper introduces the design and science cases of SCALES, a novel spectrograph with unique modes for exoplanet and astronomical research, including simulations of its expected scientific impact.

Findings

SCALES will detect colder exoplanets than current near-infrared spectrographs.

Simulations show promising science yields for exoplanet and galactic studies.

Preparations are underway for first light around 2025.

Abstract

The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is a $2-5~\mu$m, high-contrast integral field spectrograph (IFS) currently being built for Keck Observatory. With both low ($R\lesssim250$) and medium ($R\sim3500-7000$) spectral resolution IFS modes, SCALES will detect and characterize significantly colder exoplanets than those accessible with near-infrared ($\sim1-2~\mu$m) high-contrast spectrographs. This will lead to new progress in exoplanet atmospheric studies, including detailed characterization of benchmark systems that will advance the state of the art of atmospheric modeling. SCALES' unique modes, while designed specifically for direct exoplanet characterization, will enable a broader range of novel (exo)planetary observations as well as galactic and extragalactic studies. Here we present the science cases that drive the design of SCALES. We describe an end-to-end instrument simulator that we use to track requirements, and show simulations of expected science yields for each driving science case. We conclude with a discussion of preparations for early science when the instrument sees first light in $\sim2025$.