A&A 490, 435-445 (2008)
Nulling interferometry: performance comparison between space and ground-based sites for exozodiacal disc detectionD. Defrère1, O. Absil2, V. Coudé du Foresto3, W. C. Danchi4, and R. den Hartog5
1 Institut d'Astrophysique et de Géophysique, Université de Liège, 17 Allée du Six Août, 4000 Liège, Belgium
2 LAOG–UMR 5571, CNRS and Université Joseph Fourier, BP 53, 38041 Grenoble, France
3 LESIA, Observatoire de Paris-Meudon, CNRS, 5 place Jules Janssen, 92195 Meudon, France
4 NASA Goddard Space Flight Center, 8800, Greenbelt Road, Greenbelt, MD 20771, USA
5 Science Payloads and Advanced Concepts Office, ESA/ESTEC, postbus 299, 2200 AG Noordwijk, The Netherlands
Received 22 May 2008 / Accepted 11 August 2008
Context. 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.
Aims. We investigate the performance of PEGASE and FKSI for exozodiacal disc detection and compare the results with ground-based nulling interferometers.
Methods. We used the GENIEsim software (Absil et al. 2006, A&A, 448, 787) which was designed and validated to study the performance of ground-based nulling interferometers. The software has been adapted to simulate the performance of space-based nulling interferometers by disabling all atmospheric effects and by thoroughly implementing the perturbations induced by payload vibrations in the ambient space environment.
Results. Despite using relatively small telescopes (0.5 m), PEGASE and FKSI are very efficient for exozodiacal disc detection. They are capable of detecting exozodiacal discs 5 and 1 time respectively, 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.
Conclusions. Besides their main scientific goal (characterising hot giant extrasolar planets), the space-based nulling interferometers PEGASE and FKSI will be very efficient in assessing within a few minutes the level of circumstellar dust in the habitable zone around nearby main sequence stars down to the density of the solar zodiacal cloud. 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.
Key words: instrumentation: high angular resolution -- techniques: interferometric -- circumstellar matter
© ESO 2008