EDP Sciences
Free access
Issue
A&A
Volume 399, Number 1, February III 2003
Page(s) 147 - 167
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20021717


A&A 399, 147-167 (2003)
DOI: 10.1051/0004-6361:20021717

Star formation in the Vela molecular clouds

V. Young stellar objects and star clusters towards the C-cloud
F. Massi1, D. Lorenzetti2 and T. Giannini2

1  Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze, Italy
2  Osservatorio Astronomico di Roma, INAF, Via Frascati 33, 00040 Monte Porzio Catone, Roma, Italy
    e-mail: dloren@coma.mporzio.astro.it, teresa@coma.mporzio.astro.it

(Received 4 July 2002 / Accepted 14 November 2002)

Abstract
We present the latest results from a sensitive ( $K \sim 18$ mag) near-infrared ( JHK) imaging survey of IRAS selected young stellar objects associated with the Vela molecular ridge. These enlarge the sample of 12 fields, previously studied, adding 10 sites of recent star formation. The spectral energy distributions derived from near-infrared and 1.3-mm photometry allowed to identify at least 5 Class I sources. Their bolometric luminosities indicate that they are protostellar objects of intermediate mass ( $\sim $2- $10~M_{\odot}$). Herbig Ae/Be stars and compact UCHII regions could account for the far infrared emission towards some of the remaining fields. The most luminous IRAS sources have also been found associated with young embedded star clusters. The physical properties of the clusters have been determined and used to improve on the statistical relationships already suggested by our previous work. They have sizes of $\ga $0.1 pc and volume densities of 103- 104 stars pc -3. Where identified, the Class I sources tend to lie near the centre of the clusters and it is confirmed that the most massive ones are associated with the richest clusters. The less luminous Class I sources ( $\sim $10 $^{2}~L_{\odot}$) are found either isolated or within small groups of young stellar objects. It is proposed to use the relationship between the bolometric luminosity of the IRAS sources and the total number of cluster members as a test of the initial mass function at the highest masses.


Key words: stars: formation -- stars: pre-main sequence -- infrared: stars -- ISM: individual objects: Vela molecular ridge

Offprint request: F. Massi, fmassi@arcetri.astro.it

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