The Black Cloud
- a dark absorption nebula
- a Bok globule
Barnard 68 was discovered by Edward E. Barnard and was published in
his list of astronomical objects in 1919. Barnard 68 itself appears
to be a rather compact, opaque and sharply defined object upon
a rich star field. There are no stars that are between us and the
cloud - an indication that it is nearby.
Barnard 68 is 7 light months across (about 0.2 parsecs or 12,500 AU)
and is located
about 410 lightyears away, in the constellation of Ophiuchus. Barnard
68 masses about 2 solar masses. Its density is greatest in the
center and decreases as it goes away - a delicate balance of gravity
and thermal pressure. This balance is much like that found in a
main sequence star. The 12,500 AU radius is intriguing in that it
is approximately the same radius as the Oort Cloud of our sun which
measures the edge of the solar system.
Barnard 68 and its nearby kin (B69, B70, B72) are believed to be
the remains of a larger cloud that has been eaten away by the
stellar winds from new stars and supernovae.
It is expected that within the next 100,000 years, if things continue
as they are now, Barnard 68 will form a new low mass star.