Summary of Scientific Results – 2003
This year at Subaru was filled with wondrous moments of discovery from newmoons around our celestial neighbors to short-lived luminous wonders andonwards to galaxies found in the earliest years of the Universe. A new
instrument came on-line to join a collection of world-class instruments and madea discovery immediately out-of-the-box. Subaru continues to impress and attract
astronomers from around the world with its capabilities.
One of the truly unique events of 2003 was the closest approach of Mars inrecorded history. On August 27th, Mars came closer to Earth than it had in
60,000 years, a short 34-½ million miles away. This event was captured not onlywith an infrared camera from Subaru but also a high-definition television camera.
Other significant events within our Solar System included the discovery by
Subaru of 21 new satellites around Jupiter and a new satellite around Saturn.
This brought the total number of Jupiter’s moons to 58 and the total for Saturn’s
moons to 31.
A new instrument called COMICS (Cooled Mid-Infrared Camera andSpectrograph) began operations this year. It observes in the mid-infrared, thelongest wavelength among the Subaru instruments, and, as the name suggests,
performs functions as an imaging camera and spectrograph. What is exciting
about COMICS is that pretty much everything it observes will be a new discovery
because of its sensitivity and the fact that mid-infrared technology is only a few
years old. For instance, COMICS found the first direct evidence of crystalline
silicates in a proto-planetary disk surrounding a Sun-like star. Previous research
was limited to stars much more massive than the Sun.
In April of last year, Subaru presented research results from spiral galaxy NGC
4388 located within the Virgo Cluster. This year, astronomers began achallenging research program aimed at finding intracluster planetary nebulae,
and are doing so by studying the overall properties of the Virgo Cluster. So far,they have detected an isolated compact Hll region in the space between thecluster galaxies. This is a very different site for star formation than normally seen
in galaxies and shows that stars can form in the “diffuse” outskirts of galaxies.
The observation program plans to discover more of these objects and explore
their properties.
Another galactic research project at Subaru called PISCES aims at obtaining apanoramic view of distant cluster formation and the galaxy evolution therein.
Images were taken of Galaxy Cluster RX J0151.7-1357 using Suprime-Cam,showing details and qualities never before seen. Even though the central regionof the cluster was located approximately 7 billion light years away, clear structureand galactic properties were visible, providing an opportunity to map out the total
mass distribution of the cluster.

A few of the more wondrous phenomena in astronomy include supernova,hypernova, and gamma ray bursts. A supernova occurs when a star explodes
releasing its energy at an intensity that may briefly outshine its host galaxy before
fading from view. These are rare events, and on average, a supernova occurs
about once every 50 years in a galaxy the size of the Milky Way. A first for
astronomy occurred when Japanese astronomers at Subaru discovered 18
distant supernova at one time. The newly discovered supernova are located 4 to7 billion light years away. A hypernova simply describes a supernova of asupermassive star 20 to 50 times that of the Sun, and a gamma ray burst (GRB)
is the most luminous event in the Universe albeit very powerful and very shortlived (secs to mins). While studying gamma ray burst GRB 030329, astronomers
confirmed that the after-glow spectra showed similarities to a hypernova. This
was the first GRB to exhibit these characteristics.
Subaru continued to use its unique qualities to explore the distant regions of theUniverse. Located approximately 12.5 billion light years away, astronomersdiscovered a minuscule galaxy that may be an early building block of larger
galaxies found today. The petite galaxy is less than a hundredth the size of theMilky Way and has less than one percent of the mass of the Milky Way. At
approximately the same distance, other astronomers observed large-scale
structure and pattern to the Universe. And finally, not to be outdone, researchers
involved in the Subaru Deep Field Project detected the most distant galaxy everobserved at 12.8 billion light years away. The previously most distant galaxy witha redshift of 6.56 (see May 2002 result) was also recorded at Subaru; the newdistance champion has a redshift of 6.58 and was observed without the help ofgravitation lensing.