6 Summary of the results

The main results of ammonia observations of L 1340 are summarized as follows.

(i)

Mapping of the whole area of the cloud where C¹⁸O emission indicated high gas volume density ( $n \geq 10^3~{\rm cm}^{-3}$) in the NH₃(1,1) and (2,2) lines resulted in the detection of 10 dense cores in L 1340. We found the embedding cores of six candidate YSOs, namely IRAS 02238+7222, 02249+7230, F02256+7249, 02267+7226, 02276+7225 and F02277+7226. An additional object, IRAS 02263+7251 is associated with weak ammonia emission near the detection limit.

(ii)

$M > M_{{\rm BE}}$ for most cores, indicating that they are able to form stars.

(iii)

The cores with and without embedded YSOs differ from each other in nonthermal line width. The nonthermal velocity dispersion is subsonic in the starless group. Outflows from the known embedded protostars cannot account for the high $\Delta v_{{\rm NT}}$ values of cores associated with IRAS sources. Therefore the two groups differ from each other not only in evolutionary state. The nonthermal line width of cores is probably related to the masses of stars being formed in them.

(iv)

The velocity structure of L 1340 C revealed two clumps moving with supersonic velocities with respect to each other. Star formation has possibly been triggered by clump collision in this region.

(v)

The relations between the physical properties of NH₃ cores and the ¹³CO and C¹⁸O clumps are consistent with the scenario of turbulent fragmentation.

(vi)

The nonthermal line width-size relation revealed by NH₃, C¹⁸O, ¹³CO, and H I shows self-similar structure between 0.1-40 pc. Its slope is $\alpha=0.41\pm0.06$.

(vii)

The typical size, kinetic temperature and line width of NH₃ cores rank L 1340 between the high mass star forming regions Perseus and Orion B, whereas its total mass is some two orders of magnitude smaller, and no high mass stars have been formed in it. Apparently most of the ISM around L 1340 is in the form of H I.

Acknowledgements

This research was supported by the Hungarian OTKA grants T022946, T024027, T034998, T034584, and T037508. We also received support from the German-Hungarian Technological and Scientific Cooperation Project No. 121. L. V. T. acknowledges financial support from the Academy of Finland grant No. 174854. This research has made use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station (http://www.nofs.navy.mil/data/fchpix/). We thank to Péter Ábrahám and Attila Moór for their help in handling the H I data, and László Szabados for careful reading of the manuscript.