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Astron. Astrophys. 331, L65-L68 (1998)

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Letter to the Editor

The IRAM key project: small-scale structure of pre-star forming regions

Combined mass spectra and scaling laws

A. Heithausen 1, 2, F. Bensch 2, J. Stutzki 2, E. Falgarone 3 and J.F. Panis 3, 4

1 Radioastronomisches Institut der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
2 I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
3 Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris, France
4 ASIAA, Academica Sinica, P.O. Box 1-87, Nankang, Taipeh, Taiwan 115, P.R. China

Received 19 August 1997 / Accepted 6 January 1998


One objective of the IRAM key project small-scale structure of pre-star forming regions is to determine the continuation of the mass spectra for molecular cloud fragments and other scaling laws from large scales down to smallest scales accessible with single-dish telescopes. In this Letter we present first results of the combination of the small scale data from this project and large scale data obtained with the CfA 1.2 m and the KOSMA 3 m telescopes for the Polaris Flare analyzed using a Gaussian clump decomposition. For data in the 12 CO J =1 [FORMULA] 0 and 2 [FORMULA] 1 lines we find no deviation from the power law slope of the mass spectra ([FORMULA]), over a range in masses of more than at least 5 orders of magnitudes, from masses of several 10 [FORMULA] down to Jupiter masses. The size spectrum is in agreement with a power law of the form [FORMULA]. The mass-size relation is a power law of the form [FORMULA] over a range of more than 2 orders of magnitudes in size.

Key words: interstellar medium (ISM): structure - ISM: individual objects: Polaris Flare - ISM: kinematics and dynamics - turbulence

Send offprint requests to: A. Heithausen (Bonn address), (e-mail: Heithausen@Astro.Uni-Bonn.De)

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© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998