Based on Data collected at the ESO Very Large Telescope, Paranal Observatory, Chile [programs 074.D-0136(A) and 076.C-0125(A)].

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Tables 1, 2 and 4-7 are only available in electronic form at http://www.aanda.org

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... IRAF

IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc.,under contract to the National Science Foundation.

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... $\alpha={\rm d}\!\log~(\lambda F_{\lambda})/{\rm d}\!\log~(\lambda)$

Stars with $\alpha >0$ are classified as protostars (class I), those with $-1.8<\alpha <0$ as objects with a thick disk (class II), those with $-2.56<\alpha <-1.8$ as objects with a thin and evolved circumstellar disk (EV) and those with $\alpha <-2.56$ are classified as diskless objects (class III).

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