Summary of Scientific Results – 1999
This year was momentous for the National Astronomical Observatory of Japan(NAOJ) and the world of astronomy. The Subaru Telescope completedconstruction and began operations twenty years since its initial conception. The
world-class telescope sits majestically with 12 other observatories on the summitof Mauna Kea, a 14,000-foot mountain on the Island of Hawaii. Along with threeother large 8-10 meter class telescopes, Subaru has transformed the summit of
Mauna Kea into one of the premier astronomical research locations.
The Subaru Telescope is named for the Pleiades star system, known to western
astronomers as the Seven Sisters. The greatest feature of the telescope is its
single-piece primary mirror, which at 8.3 meters (27 feet) across is the world’s
largest. Thanks to its large size, the light-gathering ability of Subaru surpasses
that of the Hubble Space Telescope by more than tenfold and its field of vision is
75 times wider. Subaru is mainly used for observation in the optical and infrared
wavelengths. Its mission is to explore as wide range of astronomical phenomena
as possible, from the birth and death of individual stars to the collisions of large
galaxies. With a suite of highly sophisticated instruments, Subaru unravels themost profound mysteries of the Universe.
On January 28, 1999, Subaru had its first observation, commonly referred to as“First Light”. Images from this period included those of nearby Jupiter andSaturn, young stars forming within the Orion nebula, and the farthest known
celestial entity, a quasar 14 billion light years in the distance. A spectacular
beginning to this state-of-the-art telescope.
Observations at Subaru can be classified into two groups: one is imaging objects
to investigate their structure and brightness, and the other is spectroscopy which
spreads light into its constituent colors to study temperature, composition, andother physical characteristics. The early observations were completed with two
instruments: the Subaru Prime Focus Camera, Suprime-Cam, and the Cooled
Mid-Infrared Camera and Spectrometer, COMICS. Suprime-Cam is an 80 million
pixel digital camera positioned at Subaru’s prime focus to conduct efficient deep
imaging of a large area of sky. With a very fast focal ratio of f/1.9 and a widefield of view (30 by 24 arcminutes) each image covers an area comparable to thesize of the full moon. The faintest details visible in its images are about 1000
million times fainter than what can been seen with the unaided eye. Instrument
COMICS is a camera and spectrograph taking advantage of the thin dry air on
Mauna Kea to detect mid-infrared light from astronomical objects. COMICS
observes in long infrared wavelengths (8 to 28 microns) and is used to study theevolution (birth through death) of stars and the formation of interstellar dust, theraw material for planets.

Later in the year, Subaru showed two distinct bodies when looking at Pluto andits companion Charon. Simultaneously, Subaru made the discovery of
extraterrestrial solid ethane (C2H6), a leftover component of primordial material
from when the solar system was formed or possibly a product of when ultraviolet
light reacted with methane on Pluto. Further observations confirmed theexistence of water ice on Charon and the lack of ice on Pluto. These findings
lent support to a formation theory of the Pluto-Charon system similar to our Earthand Moon.
As the year passed, Subaru looked further into our Galaxy and confirmed thepresence of two separate protostars in L1551-IRS5, a gaseous cloud 450 lightyears away. Because of the high resolution of the Subaru Telescope, twoseparate jets, within which the protostars are located, were distinguished from anearth-based telescope for the first time. Just a little further away, Subaru imaged
the Ring Nebula M57 in great detail, allowing for a more thorough understandingof its nature. For the first time, the outer halo associated with M57 was clearlyobserved, showing that the structure of the planetary nebulae is considerably
more complex than previously considered, which, in turn, provides a moredetailed understanding of its nature.
One of the benefits of the large mirror on Subaru is that faint light from very, very
far away can be detected. This year Subaru imaged galaxies close to 10 billion
light years away at a time when the Universe was still young and less than half of
its present size; sharp and bright details in these faint galaxies appeared asnever before seen. These observations were conducted in the infrared
wavelength because distant objects have their visible light redshifted into theinfrared part of the spectrum due to the expansion of the Universe. These distantgalaxies will be examined in greater detail through the observatory project called
Subaru Deep Field. Specifically, the project will observe a one-degree wide fieldnear the North Galactic Pole, and because it passes nearly directly over MaunaKea, the Subaru Telescope is a prime candidate to study the galactic contents ofthis distant part of the Universe.