We present line observations of different molecular species toward the dense core in L483 and its bipolar outflow powered by the Class 0 object IRAS 18148-0440 . ^ { 12 } CO ( 2–1 ) maps show that the outflow is well collimated and asymmetric , and that its gas is warmer than the surrounding cloud by at least a factor of 2 .
In contrast with the outflows from other Class 0 objects , the CH _ { 3 } OH ( 2 _ { k } – 1 _ { k } ) lines in L483 do not show strong high velocity wings , although there is a small ( \sim 0.3 km s ^ { -1 } ) velocity shift approximately along the outflow direction .
We do not find evidence for a CH _ { 3 } OH abundance enhancement in the flow , and the CH _ { 3 } OH lines trace a centrally concentrated core which we model , assuming optically thin emission , as having a density gradient between r ^ { -1 } and r ^ { -1.5 } for radii between 15 ^ { \prime \prime } and 100 ^ { \prime \prime } .
H _ { 2 } CO ( 2 _ { 12 } –1 _ { 11 } ) lines show strong high-velocity wings with the same distribution as the outflow , and evidence for a H _ { 2 } CO abundance enhancement of a factor of 20 with respect to the ambient cloud .
At ambient velocities and over the central 40 ^ { \prime \prime } , this line presents a strong self absorption and a brighter blue peak , a characteristic signature of inward motions .
A simple analysis of the H _ { 2 } CO line profiles suggests an infall rate of 2 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } .

Combining the results from our observations with previous work , we discuss the evolutionary status of IRAS 18148-0440 and its outflow .
The bipolar outflow presents some characteristics common to other outflows from Class 0 sources , like high degree of collimation , gas heating , and H _ { 2 } CO abundance enhancement .
However , other characteristics , like its low velocity , the lack of bright SiO or CH _ { 3 } OH outflow wings , and the association with a NIR scattering nebula ( optically invisible ) seem more common to outflows from the more evolved Class I sources .
As IRAS 18148-0440 is a Class 0 object based on its spectral energy distribution , we propose that it is more evolved than other objects in its class , probably in transition from Class 0 to Class I .