Prof. Gao, Yu in PMO and his cooperator have performed the first Herschel  observations of the giant intergalactic filament away from the major  star forming regions in Stephan’s Quintet with the [OI] 63 μm and [C II] 158 μm fine-structure transitions, and a single para-H₂O. The filament is believed to form when a high-speed intruder to the group collided with a clumpy intergroup gas (see figure).   

 （By with GAO Yu） 

      Based  on a model of the heating and cooling of the [C II]- and [O I]-emitting  gas, Appleton et al. ‘s measurements suggest that the emission arises  from a warm diffuse medium. They found that the strong enhancement of [C  II] in the filament, relative to PAH and dust continuum, suggests that  the [C II] is heated by shocks and turbulence, but not star formation.  The  possibility that [C II] can be excited at a large scale by the  dissipation of mechanical energy (turbulence and shocks) provides a  potential new source of [C II] emission when interpreting [C II] in  high-redshift galaxies. These new results have been published in 2013,  The Astrophysical Journal Vol. 777, Page 66.