The Herschel Space Observatory was used to observe ~ 120 pre-main-sequence stars in
Taurus as part of the GASPS Open Time Key project. PACS was used to measure the
continuum as well as several gas tracers such as [OI] 63 μm, [OI] 145 μm, [CII] 158
μm, OH, H2O and CO. The strongest line seen is [OI] at 63 μm. We find a clear
correlation between the strength of the [OI] 63 μm line and the 63 μm continuum for
disk sources. In outflow sources, the line emission can be up to 20 times stronger
than in disk sources, suggesting that the line emission is dominated by the
outflow. The tight correlation seen for disk sources suggests that the emission
arises from the inner disk (< 50 AU) and lower surface layers of the disk where
the gas and dust are coupled. The [OI] 63 μm is fainter in transitional stars than
in normal Class II disks. Simple SED models indicate that the dust responsible for
the continuum emission is colder in these disks, leading to weaker line emission.
[CII] 158 μm emission is only detected in strong outflow sources. The observed line
ratios of [OI] 63 μm to [OI] 145 μm are in the regime where we are insensitive to
the gas-to-dust ratio, neither can we discriminate between shock or PDR emission.
We detect no Class III object in [OI] 63 μm and only three in continuum, at least
one of which is a candidate debris disk.