LAPCAT - searching for planets via Direct Imaging

The Large Antarctic Plateau Clear-Aperture Telescope (LAPCAT) is a proposed 8.4 metre off-axis optical/IR telescope to be located at Dome C, Antarctica. One of the primary science drivers for LAPCAT will be to directly image exo-planets. The high thermal infrared sensitivity, the high level of correction achievable with its adaptive optics system, and the telescope optical configuration make LAPCAT uniquely capable for such science.

The primary source of noise for exo-planet imaging at close angular separations arises from scattered starlight at the position of planet. Traditional coronagraphic and apodisation techniques can suppress the stellar PSF, but have significant limitations in the achievable resolving power and throughput. Techniques currently being investigated, such as the Phase-Induced Amplitude Apodization Coronograph (PIAAC) proposed by Guyon et al.(2005), should allow stellar suppression to inner working angles of several times the diffraction limit with very high efficiency. This equates to 3.5 AU at 10 pc for M band imaging with LAPCAT. Although apodised pupil masks can be used to suppress spider vane diffraction in Lyot coronographs, residual spider diffraction increases noise and can effect speckle statistics. The PIAAC technique is likely to suffer from similar limitations, and thus the un-obscured primary of LAPCAT is advantageous.

In a 24 hour integration, LAPCAT should detect a 1.2 Mjup 1 Gyr old planet at 10 pc, or a more mature 5 Gyr planet of 4.2 Mjup. These are significantly lower masses than are detectable with existing facilities, and arecomparable with the detection limits of future Extremely Large Telescopes at mid-latitude sites. Younger (100 Myr) Jupiter mass planets at very wide (20 AU) orbits should be detectable with LAPCAT out to 60 pc. LAPCAT thus provides a significant extension of the parameter space of other planet detection methods. The higher spatial resolution of ELT class telescopes will enable imaging of planets at closer orbits than LAPCAT. An ELT located in Antarctica would thus be an exceptionally powerful facility for this science.


LAPCAT: the Large Antarctic Plateau Clear-Aperture Telescope
Storey, J. W. V.; Angel, R.; Lawrence, J.; Hinz, P.; Ashley, M. C. B.; Burton, M. G.
Astronomy in Antarctica, 26th meeting of the IAU, Special Session 7, 22-23 August, 2006 in Prague, Czech Republic, SPS7, #31 (08/2006)

LAPCAT: the Large Antarctic Plateau Clear-Aperture Telescope
Storey, John; Angel, Roger; Lawrence, Jon; Hinz, Phil; Ashley, Michael; Burton, Michael
Ground-based and Airborne Telescopes. Edited by Stepp, Larry M.. Proceedings of the SPIE, Volume 6267, pp. 62671E (07/2006)

What a really big Antarctic telescope could achieve
J. W. V. Storey, M. C. B. Ashley, M. G. Burton and J. S. Lawrence

J.W.V. Storey, J.R.P. Angel, J.S. Lawrence, P. Hinz

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