Paula Cleggett-Haleim
Headquarters, Washington, D.C.                      November 13, 1992
(Phone:  202/358-0883)
 
Jim Eliott
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-6256)
 
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
(Phone:  410/338-4757)
 
 
RELEASE:  92-203
 
HUBBLE OBSERVES MOST DISTANT KNOWN GALAXY IN UNIVERSE
 
	NASA's Hubble Space Telescope (HST) has revealed a chain of 
luminous knots in the core of the most distant known galaxy -- one that 
existed in the infancy of the universe and is located more than 10 billion 
light years from Earth. 
 
	"These knots could be giant clusters of stars.  If that is so, then 
each  knot would contain about 10 billion stars and would be about 1,500 light 
years across," said Dr. George Miley of Leiden University in the Netherlands 
and leader of the international astronomer team which examined the galaxy.
 
	An alternative theory is that the knots are gas or dust clouds caught 
in a "searchlight" beam of energy from a massive black hole hidden at the 
galaxy's core.
 
	The galaxy's great distance from Earth indicates that it was formed 
only 1 or 2 billion years after the Big Bang, which marked the beginning of 
the observable universe.  Most galaxies probably formed during this early 
epoch.
 
	The new photos, taken with the HST's wide field and planetary 
camera, reveal detail ten times better than photographs previously taken 
with ground-based telescopes.

	The galaxy, designated 4C 41.17, also is known as a radio galaxy.  
Radio galaxies produce powerful, extended radio emissions.  Several have 
been discovered by this international team in the past few years at great 
distances from the Earth.
 
	In the case of 4C 41.17, astronomers presume that a massive black 
hole, rotating in the core of the galaxy, is producing twin jets of particles 
moving at enormous speed.  The energy from the jets would be the source of 
the radio emissions.
 
	The Hubble photographs are remarkably similar to images of the galaxy 
produced on the basis of the radio emissions, Miley said.
 
	These corresponding images suggest that the high velocity particle 
jets compress gas and dust along their paths, triggering the formation of 
new stars.  This would account for the elongated optical appearance of the 
galaxy.
 
	If this explanation is accurate, the knots along the jet paths would be 
clusters of stars in "enormous numbers, the products of the highly disturbed 
inner region of the primeval galaxy," Miley said.
 
	It also is possible, said Miley, that the light photographed by the HST 
is not due to stars along the jet paths, but rather is light from a disk of 
material surrounding the black hole which is being scattered off clouds of 
gas or dust.  
 
	An active galactic nucleus of this description is called a quasar.  It 
is hidden from optical view by a thick dust shroud which allows light to escape 
only along the radio or jet axis.
 
	Hubble can help discriminate between these possibilities by further 
studying the colors and other properties of these and similar objects.  After 
the scheduled Space Shuttle servicing mission for Hubble in late 1993,  HST 
then can be used to carry out detailed studies of many galaxies at distances 
comparable with 4C41.17.  
 
	"More than 50 are now known," said Miley, "observing them with the 
renewed Hubble would provide us with an important new window through 
which we can glimpse the early history of our universe."
 
	The observations of galaxy 4C 41.17 were carried out by Miley and co-
investigators Kenneth Chambers, of the University of Hawaii; Wil van Breugel 
of Lawrence Livermore National Laboratories of the University of California; 
and Duccio Macchetto of the Space Telescope Science Institute, Baltimore 
and the European Space Agency.  The results will be published in the 
December 20 issue of Astrophysical Journal Letters.
 
	This research was supported by the Netherlands Organization for the 
Advancement of Pure Research, the Space Telescope Science Institute, the 
European Space Agency, NASA, the European Economic Community, NATO 
and the U.S. Department of Energy. 
 
	The Hubble Space Telescope is a project of international cooperation 
between NASA and the European Space Agency.
 
- end -
 
Editors Notee:  A photograph to illustrate this story is available to media 
representatives through NASA's Broadcast and Imaging Branch, (202/453-
8375).
                        B&W               
                     92-H-748