  The young star beta Pictoris is well known for its dusty debris disk,
produced through the grinding down by collisions of planetesimals,
kilometre-sized bodies in orbit around the star. In addition to dust, small
amounts of gas are also known to orbit the star, likely the result from
vaporisation of violently colliding dust grains. The disk is seen edge on and
from previous absorption spectroscopy we know that the gas is very rich in
carbon relative to other elements. The oxygen content has been more difficult
to assess, however, with early estimates finding very little oxygen in the gas
at a C/O ratio 20x higher than the cosmic value. A C/O ratio that high is
difficult to explain and would have far-reaching consequences for planet
formation. Here we report on observations by the far-infrared space telescope
Herschel, using PACS, of emission lines from ionised carbon and neutral oxygen.
The detected emission from C+ is consistent with that previously reported being
observed by the HIFI instrument on Herschel, while the emission from O is hard
to explain without assuming a higher-density region in the disk, perhaps in the
shape of a clump or a dense torus, required to sufficiently excite the O atoms.
A possible scenario is that the C/O gas is produced by the same process
responsible for the CO clump recently observed by ALMA in the disk, and that
the re-distribution of the gas takes longer than previously assumed. A more
detailed estimate of the C/O ratio and the mass of O will have to await better
constraints on the C/O gas spatial distribution.
