EMBARGOED UNTIL: 3:00 PM (EST) November 29, 1995

PHOTO NO.: STScI-PRC95-48


BROWN DWARF DISCOVERED AROUND STAR GLIESE 229

These two false-color telescope images reveal the faintest object ever
seen around a star beyond our Sun, and the first unambiguous detection
of a brown dwarf.  The brown dwarf, called GL229B, orbits the red dwarf
star Gliese 229, located approximately 18 light-years away in the
constellation Lepus.  The brown dwarf is about 20-50 times the mass of
Jupiter, but is so dense it is about the same diameter as Jupiter
(80,000 miles).

Brown dwarfs are a mysterious class of long-sought objects that form
the same way stars do, by condensing out of a cloud of hydrogen gas.
However, they do not accumulate enough mass to sustain nuclear fusion
at their core, which make stars shine.

[left] - The brown dwarf (center) was first observed in far red light
October 27, 1994 using the adaptive optics device and a 60-inch
reflecting telescope on Palomar Mountain in California.  Another year
was required to confirm that the object was actually gravitationally
bound to the companion star. GL229B is at least four billion miles from
its companion star, roughly the separation between the planet Pluto and
our Sun. Even though a cornograph on the detector masked most of the
light from the star, which is off the left edge of the image, it is so
bright relative to the brown dwarf the glare floods the detector.

Credit: T. Nakajima (Caltech), S. Durrance (JHU)

[right] - This image of the GL229B (center) was taken with Hubble Space
Telescope's Wide Field Planetary Camera-2, in far red light, on
November 17, 1995.  The Hubble observations will be used to accurately
measure the brown dwarf's distance from Earth, and yield preliminary
data on its orbital period, which may eventually offer clues to the
dwarf's origin. Though the star Gliese 229 is off the edge of the
image, it is so bright it floods Hubble detector. The diagonal line is
a diffraction spike produced by the telescope's optical system.

Credit: S. Kulkarni (Caltech), D.Golimowski (JHU) and NASA

Image files in GIF and JPEG format, captions, and press release text
may be accessed on Internet via anonymous ftp from ftp.stsci.edu in
/pubinfo:
                                GIF             JPEG
PRC95-48  Brown Dwarf Gl229B  gif/Gl229B.gif jpeg/Gl229B.jpg

Higher resolution digital versions (300dpi JPEG) of the release
photograph will be available temporarily in /pubinfo/hrtemp:  95-48.jpg
(color) and 95-48b.jpg (black & white).  GIF and JPEG images, captions
and press release text are available via World Wide Web at URL
http://www.stsci.edu/pubinfo/PR/95/48.html, or via links in
http://www.stsci.edu/pubinfo/Latest.html, and in
http://www.stsci.edu/pubinfo/Pictures.html.