Nulling interferometry: performance comparison between space and ground-based sites for exozodiacal disc detection

TL;DR

This paper compares space-based and ground-based nulling interferometers for detecting exozodiacal dust, showing space instruments like Pegase and FKSI outperform ground-based ones in sensitivity and speed, aiding future life-finding missions.

Contribution

It provides a performance comparison between space and ground-based nulling interferometers for exozodiacal disc detection, highlighting the superior sensitivity of space-based instruments.

Findings

Space interferometers can detect denser exozodiacal discs than ground-based ones.

FKSI can achieve sensitivity for most targets in the Darwin/TPF catalogue.

Space-based interferometers are ideal for preparing future life-finding missions.

Abstract

Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet Finder (TPF). Besides paving the technological way to Darwin/TPF, the space-based infrared interferometers Pegase and FKSI (Fourier-Kelvin Stellar Interferometer) will be valuable scientific precursors in that respect. In this paper, we investigate the performance of Pegase and FKSI for exozodiacal disc detection and compare the results with ground-based nulling interferometers. Besides their main scientific goal (characterising hot giant extrasolar planets), Pegase and FKSI are very efficient in assessing within a few minutes the level of circumstellar dust in the habitable zone around nearby main sequence stars. They are capable of detecting exozodiacal discs respectively 5 and 1 time as dense as the solar zodiacal cloud and they outperform any ground-based instrument. Unlike Pegase, FKSI can achieve this sensitivity for most targets of the Darwin/TPF catalogue thanks to an appropriate combination of baseline length and observing wavelength. The sensitivity of Pegase could, however, be significantly boosted by considering a shorter interferometric baseline length. These space-based interferometers would be complementary to Antarctica-based instruments in terms of sky coverage and would be ideal instruments for preparing future life-finding space missions.