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Abstract. The Chamaeleon  dark cloud (Cha ) has been mapped in C 18 O (J = 1−0) with an angular resolution of 1 using the SEST telescope. The large scale structures previously observed with lower spatial resolution in the cloud turn into a network of clumpy filaments. The automatic Clumpfind routine developed by Williams et al. (1994) is used to identify individual clumps in a consistent way. Altogether 71 clumps were found and the total mass of these clumps is 230 M . The dense "cores" detected with the NANTEN telescope ) and the very cold cores detected in the ISOPHOT serendipity survey (Tóth et al. 2000) form parts of these filaments but decompose into numerous "clumps". The filaments are preferentially oriented at right angles to the large-scale magnetic field in the region. We discuss the cloud structure, the physical characteristics of the clumps and the distribution of young stars. The observed clump mass spectrum is compared with the predictions of the turbulent fragmentation model of Padoan & Nordlund (2002). Agreement is found if fragmentation has been driven by very large-scale hypersonic turbulence, and if by now it has had time to dissipate into modestly supersonic turbulence in the interclump gas. According to numerical simulations, large-scale turbulence should have resulted in filamentary structures as seen in Cha . The well-oriented magnetic field does not, however, support this picture, but suggests magnetically steered large-scale collapse. The origin of filaments and clumps in Cha  is thus controversial. A possible solution is that the characterization of the driving turbulence fails and that in fact different processes have been effective on small and large scales in this cloud.

Abstract. We surveyed 55 northern non-stellar H 2 O masers in the CS J = 2 − 1 line with the 20-m Onsala radio telescope and detected 47 CS cores associated probably with 50 masers. The CS emission for this sample is weaker on the average than for the similar southern sample studied by us earlier at SEST. Most of the detected cores were mapped in CS. The CS peaks were observed also in the C 34 S J = 2 − 1 and in the CO J = 1 − 0 lines. We present CS maps as well as CO, CS and, when available, C 34 S spectra for the 26 best studied cores.From the CS maps and optically thin C 34 S emission we derive the basic physical parameters of the cores: size, LTE mass, mean density, virial mass. Combining the present results with the previous SEST data we obtain statistical distributions of the core parameters. The CO brightness temperature distribution for most cores ranges from ∼15 K to ∼50 K with a peak at 20 − 30 K. The typical sizes of the cores are L ∼ 1.0 − 1.5 pc. The mean density lies in the range n ∼ 10 3 − 10 5 cm −3 which is much lower than densities needed for CS excitation from multitransitional analysis. The slope of the mass spectrum for M > ∼ 1000 M is 1.6 ± 0.3. The ratio of the IR luminosity of associated IRAS point sources to mass peaks at ∼ 10 L /M . The CS line widths are highly supersonic (∼ 1.5 − 9 km s −1 ). We analyze the dependences of these parameters on galactocentric distance R. The mean density of the cores drops with increasing R in the interval R ≈ 7 − 14 kpc. It is consistent with an exponential law with a scale length of ∼ 3 kpc. The IR luminosity to mass ratio changes probably in a similar way. The core size increases with R in accordance with the density decrease and constant mass.Send offprint requests to: I. Zinchenko Correspondence to: zin@appl.sci-nnov.ru Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.htmlThe comparison of the CS and C 34 S data shows almost no broadening of the CS lines due to optical depth effects. This can be probably explained by small scale clumpiness in the cores. The velocity difference between the CS cores and H 2 O masers is close to zero on the average with the standard deviation of ∼ 7 km s −1 .

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