03 February, 1998. The number of Jupiter-like planets found by the
Doppler technique to be orbiting other stars has risen to 9 (ck),
all below the brown dwarf limit of 0.13 Jupiter masses. We are now
beginning to see a variety of different kinds of planetary systems.
One planet (16 Cygni B) has been found to orbit a member of a
binary system. It and one other have highly elliptical orbits.
Most of the Jupiter-like planets are tucked near their parent
stars, quite unlike what we find in our own system. Such large
planets should form far from their stars where the temperature in
the birthing nebular cloud is low. Theory now shows that friction
within a thick circumstellar disk of gas can drag the planet inward
until its orbital radius is quite small, giving what we observe for
stars like 51 Pegasi, in which the planet's semimajor axis is only