galaxies & galaxy evolution
little known about galaxies beyond a few billion
imaging traces the evolution of galaxies and rate
of star formation. Galaxies seen within a billion
years of the Big Bang.
supernovae as distance indicators
possible to discriminate supernova light from light
of host galaxy.
with ground-based telescope surveys HST detects
supernovae all the way back to half of universe's
age. The results show universe is accelerating.
rate of expansion
research groups disagree by a factor of two, this
yields estimates for age of universe as between
10 to 20 billion years.
converges toward 10 percent accuracy, suggesting
an age of 12-14 billion years.
known about circumstellar environment. Jet-like
features noted, stellar disks seen in infrared wavelengths.
disks are common. Circumstellar disks confine and
direct the flow of jets.
data are suggestive, but telescopes cannot see close
enough to suspected black holes to provide absolute
precisely measures gas velocity around black hole,
providing definitive proof. HST surveys reveal that
black holes are common to the cores of galaxies.
originated early in the universe. Some are surrounded
by a "fuzz" which is interpreted as the host galaxy.
Quasars are likely powered by black holes.
clearly resolves a variety of galaxies hosting QSOs.
Some are involved in mergers with other galaxies.
These collsions fuel the central black hole.
examples are known.
small lenses uncovered in medium deep survey. Lenses
have potential to contribute to cosmological tests
of the curvature of space and age of universe.
and eclipses of Pluto's moon Charon yield a brightness
map of surface.
confirms earlier map by showing a variegated surface.
Images clearly separate planet from its moon, Charon.
nearest supernova in 400 years, and armada of telescopes
watch its changes following the February. 1987 explosion.
HST has the resolution to trace yearly change happening
at the sub-light-year scale, including changes in
the fireball debris and circumstellar ring of enriched
the Milky Way's central bulge and those of nearby
galaxies can be viewed in detail.
bulges formed early in the universe along with elliptical
galaxies. Smaller bulges can be "inflated" by ongoing
starbirth fueled by disk instabilities or galaxy