Lynds 1340 , a molecular cloud forming intermediate-mass stars , has been mapped in the NH _ { 3 } ( 1,1 ) and ( 2,2 ) transitions with the Effelsberg 100-m telescope .
We observed the whole area of the cloud where C ^ { 18 } O emission was detected earlier , at a 40 \arcsec grid , with additional positions towards the C ^ { 18 } O peaks and optically invisible IRAS point sources .
Our observations covered an area of 170 arcmin ^ { 2 } , corresponding to about 5.15 pc ^ { 2 } at a distance of 600 pc , and revealed 10 ammonia cores .
The cores , occupying some 7 % of the mapped area , probably represent the highest density regions of L 1340 .
Their total mass is \sim 80 M _ { \sun } , about 6 % of the mass traced by C ^ { 18 } O .
Six cores are associated with optically invisible IRAS point sources .
Their average nonthermal line width is 0.78 km s ^ { -1 } , while the same quantity for the four starless cores is 0.28 km s ^ { -1 } .
We suggest that the narrow-line cores are destined to form low-mass stars , whereas small groups of intermediate-mass stars are being formed in the turbulent cores .
The features traced by NH _ { 3 } , ^ { 13 } CO , C ^ { 18 } O and H i obey the line width–size relation \Delta v _ { \mathrm { NT } } \propto R _ { 1 / 2 } ^ { 0.41 } .
Comparison of sizes , densities and nonthermal line widths of ammonia cores with those of C ^ { 18 } O and ^ { 13 } CO structures supports the scenario in which core formation has been induced by turbulent fragmentation .
The typical physical properties of the NH _ { 3 } cores of L 1340 , \langle R _ { 1 / 2 } \rangle =0.08 pc , \langle T _ { \mathrm { kin } } \rangle =13.8 K , \langle \Delta v _ { \mathrm { total } } \rangle =0.64 km s ^ { -1 } , and \langle M \rangle =9 M _ { \sun } are close to those of the high-mass star forming Perseus and Orion B clouds .