The Subaru Telescope, located on the summit of Mauna Kea, is dedicated to exploring the cosmos, gaining a deeper and more thorough understanding of everything that surrounds us. With an 8.2-meter mirror and a suite of sophisticated instruments, astronomers at Subaru Telescope explore nearby stars looking for planetary systems. A giant step towards this goal was made recently with the “first-light” inauguration of a new state-of-the-art instrument.
There are eight innovative cameras and spectrographs at Subaru optimized for various astronomical investigations in optical and near-infrared wavelengths. On the night of December 3, 2007, a new instrument was brought to life, HiCIAO (High Contrast Instrument for the Subaru Next Generation Adaptive Optics). The HiCIAO camera is designed as a technologically adaptable system that will replace the infrared CIAO (Coronagraphic Imager with Adaptive Optics) unit that has been in operation since April 2000. Both systems are designed to block out the harsh direct light from a star, so that nearby faint objects such as planets can be viewed. The new system benefits from a contrast improvement of 10 to 100 times better than before, allowing astronomers glimpses into regions never explored. A further advantage of the HiCIAO camera is that it will be used in concert with an adaptive optics (AO) system that was recently significantly upgraded, which, in turn, increased the clarity of Subaru’s vision by a factor of ten, opening up more of the night sky to observing. The new AO system uses 188 actuators behind a deformable mirror to remove the atmospheric distortion from its view, allowing Subaru Telescope to observe close to its theoretical performance limits. In conjunction with the new AO system a laser guide star system was installed so that any part of the sky can now be observed.
The HiCIAO system, initiated in 2004, was developed by an ambitious team of scientists and engineers from the Subaru Telescope, National Astronomical Observatory of Japan, and the University of Hawaii’s Institute for Astronomy. Dr. Ryuji Suzuki, a Subaru astronomer leading the HiCIAO project, says “the unique instrument was primarily designed for the direct detection of extrasolar planets and disks”. The system’s innovative design allows for high contrast coronagraphic techniques in three observing modes: direct imaging, polarization differential imaging, and spectral differential imaging. HiCIAO directly detects and characterizes young extrasolar planets and brown dwarfs, sub-stellar objects that occupy the mass range between that of large gas giant planets (e.g. Jupiter) and the lowest mass stars. With the aid of the laser guide star AO system, HiCIAO targets dim objects including young stars, protostars, and star forming regions. HiCIAO is also extremely useful detecting faint dust disks around nearby stars studying small-scale and inner disk structures and dust grain properties, leading to a clearer understanding of extra-solar planetary systems and their evolutionary processes. Dr. Suzuki reports that “although we already know more than 250 extrasolar planets, they have all proven their existence by indirect evidences like the Doppler or transit method. Because the direct imaging of an extrasolar planet has never been done, if it happens, that will be exciting”. Subaru Telescope hopes to be the first to directly observe a planet outside our solar system.