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In this paper we present the mass functions in the substellar regime of three young open clusters, IC 348, σ Orionis and Pleiades, as derived using the data from the 2 Micron All Sky Survey (2MASS) catalogue which has a limiting magnitude of K s ∼ 15, and the latest version of the Guide Star Catalogue (GSC) which has a limiting magnitude of F 4 ∼ 21. Based on recent evolutionary models for low mass stars, we have formulated the selection criteria for stars with masses below 0.5M ⊙ . Using a statistical approach to correct for the background contamination, we derive the mass function of objects with masses ranging from 0.5M ⊙ down to the substellar domain, well below the Hydrogen Burning Mass Limit. The lowest mass bins in our analysis are 0.025, 0.045 and 0.055 M ⊙ for IC 348, σ Orionis and Pleiades, respectively. The resultant slopes of the mass functions are 0.8 ± 0.2 for IC 348, 1.2 ± 0.2 for σ Orionis and 0.5 ± 0.2 for Pleiades, which are consistent with the previous results. The contribution of objects below 0.5 M ⊙ to the total mass of the cluster is ∼40%, and the contribution of objects below 0.08 M ⊙ to the total mass is ∼4%.

IRAS 17256-3631 is a southern Galactic massive star forming region located at a distance of 2 kpc. In this paper, we present a multiwavelength investigation of the embedded cluster, the H II region, as well as the parent cloud. Radio images at 325, 610 and 1372 MHz were obtained using GMRT, India while the near-infrared imaging and spectroscopy were carried out using UKIRT and Mt. Abu Infrared Telescope, India. The near-infrared K-band image reveals the presence of a partially embedded infrared cluster. The spectral features of the brightest star in the cluster, IRS-1, spectroscopically agrees with a late O or early B star and could be the driving source of this region. Filamentary H 2 emission detected towards the outer envelope indicates presence of highly excited gas. The parent cloud is investigated at far-infrared to millimeter wavelengths and eighteen dust clumps have been identified. The spectral energy distributions (SEDs) of these clumps have been fitted as modified blackbodies and the best-fit peak temperatures are found to range from 14 − 33 K, while the column densities vary from 0.7 − 8.5 × 10 22 cm −2 . The radio maps show a cometary morphology for the distribution of ionised gas that is density bounded towards the north-west and ionization bounded towards the south-east. This morphology is better explained with the champagne flow model as compared to the bow shock model. Using observations at near, mid and farinfrared, submillimeter and radio wavelengths, we examine the evolutionary stages of various clumps.

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