We present a set of detailed molecular line maps of the region associated with the giant Herbig-Haro flow HH 315 , from the young star PV Cephei , aimed at studying the outflow-cloud interaction .
Our study clearly shows that the HH 315 flow is effecting the kinematics of its surrounding medium , and has been able to redistribute considerable amounts of the surrounding medium-density ( \sim 10 ^ { 3 } cm ^ { -3 } ) gas in its star-forming core as well at parsec-scale distances from the source .
The single-dish observations include a map of the outflow in the ^ { 12 } CO ( 2–1 ) line , with a beam size of 27″ , and more extended maps of the outflow region in the ^ { 12 } CO ( 1–0 ) and ^ { 13 } CO ( 1–0 ) lines , with 45″ and 47″ beam sizes , respectively .
A companion paper to this one presents higher-resolution ( IRAM 30-m ) observations , and discusses their implications ( Arce & Goodman 2002 ) .
The giant molecular outflow HH 315 is a highly asymmetric bipolar flow with a projected linear extent of about 2 pc .
Our results indicate that the two outflow lobes are each interacting with the ambient medium in different ways .
The southern ( redshifted ) lobe , with a mass of 1.8 M _ { \sun } , interacts with a dense ambient medium , very close to the young stellar outflow source , and its kinetic energy is comparable to both the turbulent and gravitational binding energy of its host cloud ( of order 10 ^ { 44 } erg ) .
In addition , we find evidence that the southern lobe is responsible for the creation of a cavity in the ^ { 13 } CO emission .
In contrast , the northern ( mainly blueshifted ) outflow lobe , with a total mass of 4.8 M _ { \sun } , extends farther from PV Ceph and interacts with ambient gas much less dense than the southern lobe .
There is very little ^ { 13 } CO emission north of the outflow source , and the only prominent ^ { 13 } CO emission is a shell-like structure coincident with the outer edge of the northern lobe , about 1.2 pc northwest of PV Ceph .
It appears that the northern lobe of the HH 315 outflow has been able to “ push ” aside a substantial fraction of the gas in the area , piling it in a dense shell-like structure at its edges .
In addition , we find that about 50 % of the gas in the region of the northern lobe has been put in motion by the outflow , and that the northern outflow lobe is responsible for a velocity gradient in the ambient gas .