A new concept for the combination of optical interferometers and high-resolution spectrographs

TL;DR

This paper proposes a cost-effective method to combine existing optical interferometers with high-resolution spectrographs, enabling high spectral and spatial resolution observations without building new complex instruments.

Contribution

It demonstrates the feasibility of coupling existing high-resolution spectrographs with interferometers, addressing technical challenges and providing a concept study for VLTI and UVES integration.

Findings

Coupling existing instruments is feasible with current technology.

The approach reduces costs and minimizes impact on existing programs.

Technical challenges like fringe tracking and dispersion are manageable.

Abstract

The combination of high spatial and spectral resolution in optical astronomy enables new observational approaches to many open problems in stellar and circumstellar astrophysics. However, constructing a high-resolution spectrograph for an interferometer is a costly and time-intensive undertaking. Our aim is to show that, by coupling existing high-resolution spectrographs to existing interferometers, one could observe in the domain of high spectral and spatial resolution, and avoid the construction of a new complex and expensive instrument. We investigate in this article the different challenges which arise from combining an interferometer with a high-resolution spectrograph. The requirements for the different sub-systems are determined, with special attention given to the problems of fringe tracking and dispersion. A concept study for the combination of the VLTI (Very Large Telescope Interferometer) with UVES (UV-Visual Echelle Spectrograph) is carried out, and several other specific instrument pairings are discussed. We show that the proposed combination of an interferometer with a high-resolution spectrograph is indeed feasible with current technology, for a fraction of the cost of building a whole new spectrograph. The impact on the existing instruments and their ongoing programs would be minimal.