(This press release from April
27, 1994, is reproduced courtesy of the Space Telescope Science Institute.)
This Hubble Space Telescope image (right) reveals the faint host
galaxy that a bright quasar dwells within. The wealth of new
detail in this picture helps solve a three-decade old mystery
about the true nature of quasars, the most distant and energetic
objects in the universe.
The HST image shows clearly that the quasar, called 1229+204,
lies in the core of a galaxy that has a common shape consisting
of two spiral arms of stars connected by a bar-like feature. The
host galaxy is in a spectacular collision with a dwarf galaxy.
The collision apparently fuels the quasar engine at the galaxy
center - presumably a massive black hole -- and also triggers
many sites of new star-formation.
The image is one of a pair of relatively nearby quasars that were
selected as early targets to test the resolution and dynamic
range of HSTs newly-installed Wide Field and Planetary Camera,
which contains special optics to correct for a flaw in Hubbles
primary mirror. The observations were made by Dr. John Hutchings
of Dominion Astrophysical Observatory in Victoria, British
Columbia. The project was impossible from ground-based
telescopes, says Dr. Hutchings, who has been researching quasars
for many years. The sharpness of the Hubble pictures is leading
to major new discoveries almost anywhere you point it in the
sky.
Quasars are the most distant objects in the universe, and so are
among the earliest objects known to have formed in the young
universe, more than 12 billion years ago. The most widely
accepted notion is that quasars are in galaxies with active,
supermassive black holes at their centers. However, because of
their enormous distance, the `host galaxies appear very small
and faint, and are very hard to see against the much brighter
quasar light at the center. Though a quasar might no be much
larger than our solar system it releases as much energy as
billions of stars.
Though a previous ground based observation using the
Canada-France-Hawaii Telescope (at 0.5 arcsec resolution) first
identified the barred spiral galaxy in 1229+204, Hubble shows
clearly the galaxys structure and reveals details of the
collision.
Hubble reveals that an extended blue feature on one side of the
galaxy is really a string of knots, which are probably massive
young star clusters. The star clusters were most likely formed
as a result of a collision between the host galaxy and a small
gas-rich companion. HST also reveals shell-like structures
along the bar that might be produced by gravitational tidal
resonance forces between the spiral and its companion.
Credit: Dr. John Hutchings,Dominion Astrophysical Observatory, NASA