TARdYS: Design and Prototype of an Exoplanet Hunter for TAO using a R6 Echelle Grating

TL;DR

This paper introduces TARdYS, a cost-effective high-resolution infrared spectrograph designed for exoplanet detection, utilizing a R6 Echelle grating and innovative optical configurations to optimize performance and reduce costs.

Contribution

The paper presents a novel optical design for a high-resolution IR spectrograph that is cost-effective and suitable for the TAO telescope, with prototype results demonstrating its feasibility.

Findings

Achieves R=60,000 resolution in the 0.843-1.117 μm range.

Prefers White Pupil setup for better image quality.

Prototype shows promising early results at ambient temperature.

Abstract

One limitation in characterizing exoplanet candidates is the availability of infrared, high-resolution spectrographs. An important factor in the scarcity of high precision IR spectrographs is the high cost of these instruments. We present a new optical design, which leads to a cost-effective solution. Our instrument is a high-resolution (R=60,000) infrared spectrograph with a R6 Echelle grating and an image slicer. We compare the best possible performance of quasi-Littrow and White Pupil setups, and prefer the latter because it achieves higher image quality. The instrument is proposed for the University of Tokyo Atacama Observatory (TAO) 6.5 m telescope in Chile. The Tao Aiuc high Resolution (d) Y band Spectrograph (TARdYS) covers 0.843-1.117 um. To reduce the cost, we squeeze 42 spectral orders onto a 1K detector with a semi-cryogenic solution. We obtain excellent resolution even when taking realistic manufacturing and alignment tolerances as well as thermal variations into account. In this paper, we present early results from the prototype of this spectrograph at ambient temperature.