EDP Sciences
Free access
Volume 490, Number 1, October IV 2008
Page(s) 435 - 445
Section Astronomical instrumentation
DOI http://dx.doi.org/10.1051/0004-6361:200810248
Published online 11 September 2008

A&A 490, 435-445 (2008)
DOI: 10.1051/0004-6361:200810248

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

D. 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
    e-mail: defrere@astro.ulg.ac.be
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 ($\leq$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