Coronagraphic search for exo-planets with a hypertelescope: I. In the thermal IR

Following the idea developed in Boccaletti et al. (2000), a snapshot imaging interferometer is proposed as an al- ternative to the nulling interferometer for the NASA Origin project, "Terrestrial Planet Finder". This concept is based on hypertelescope, i.e. densified-pupil, imaging (Labeyrie 1996) and phase-mask coronagraphy (Rouan et al. 2000) 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.

[1]  D. Mouillet,et al.  A planet on an inclined orbit as an explanation of the warp in the β Pictoris disc , 1997 .

[2]  J. Mariotti,et al.  Planets outside the solar system : theory and observations , 1999 .

[3]  A. Labeyrie,et al.  The Four-Quadrant Phase-Mask Coronagraph. I. Principle , 2000 .

[4]  Pierre Riaud,et al.  The Four‐Quadrant Phase‐Mask Coronagraph. II. Simulations , 2001 .

[5]  F. Roddier,et al.  STELLAR CORONOGRAPH WITH PHASE MASK , 1997 .

[6]  A. Labeyrie,et al.  First images on the sky from a hyper telescope , 2000 .

[7]  Stuart Bowyer,et al.  The 1997 reference of diffuse night sky brightness , 1998 .

[8]  R. Bracewell,et al.  Searching for nonsolar planets , 1979 .

[9]  Olivier Guyon,et al.  A nulling wide field imager for exoplanets detection and general astrophysics , 2002, astro-ph/0205523.

[10]  P.R. Lawson.  The Terrestrial Planet Finder , 2001, 2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542).

[11]  Marc Ollivier,et al.  Could We Search for Primitive Life on Extrasolar Planets in the Near Future , 1996 .

[12]  R. Bracewell.  Detecting nonsolar planets by spinning infrared interferometer , 1978, Nature.

[13]  C. Aime,et al.  Total coronagraphic extinction of rectangular apertures using linear prolate apodizations , 2002 .

[14]  M. Pérault,et al.  Diffuse infrared emission from the galaxy. I: Solar neighborhood , 1988 .

[15]  Antoine Labeyrie,et al.  Resolved imaging of extra-solar planets with future 10 100 km optical interferometric arrays , 1996, astro-ph/9602093.

[16]  C. Moutou,et al.  Snapshot Coronagraphy with an Interferometer in Space , 2000 .