Coronagraphic search for exo-planets with a hypertelescope^*

I. In the thermal IR

¹ LESIA, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France
² LISE-Observatoire de Haute-Provence, 04870 St Michel l'Observatoire, France e-mail: sgohp@obs-hp.fr; lardiere@obs-hp.fr; dejonghe@obs-hp.fr
³ Collège de France, 11 place M. Berthelot, 75321 Paris, France e-mail: Labeyrie@obs-hp.fr
⁴ LUTH, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France
⁵ Observatoire de Haute-Provence, 04870 St Michel l'Observatoire, France e-mail: arnold@obs-hp.fr

Corresponding author: P. Riaud, pierre.riaud@obspm.fr

Received: 23 May 2002
Accepted: 23 August 2002

Abstract

Following the idea developed in Boccaletti et al. (2000), a snapshot imaging interferometer is proposed as an alternative to the nulling interferometer for the NASA Origin project, “Terrestrial Planet Finder". This concept is based on hypertelescope, i.e. densified-pupil, imaging (Labeyrie [CITE]) and phase-mask coronagraphy (Rouan et al. [CITE]) to combine a very high angular resolution and a deep attenuation of starlight (10^-8) as required to image extra-terrestrial planets. This article aims at presenting thorough estimations of the signal to noise ratio for different classes of stars (from F0V to M5V) and includes several sources of background noise (zodiacal and exozodiacal lights for instance). In addition, numerical simulations have been carried out and are compared to the analytical results. We find that the image of Earth-like planets can be formed with a large hypertelescope (~80 m) in the thermal infra-red for about 73% of the stars within 25pc.