K. K. Mallick

Study of morphology and stellar content of the Galactic H ii region IRAS 16148−5011

An investigation of the IRAS 16148−5011 region – a cluster at a distance of 3.6 kpc – is presented here, carried out using multiwavelength data in near-infrared (NIR) from the 1.4 m Infrared Survey Facility telescope, mid-infrared (MIR) from the archival Spitzer GLIMPSE (Galactic Legacy Infrared Midplane Survey Extraordinaire) survey, far-infrared (FIR) from the Herschel archive, and low-frequency radio continuum observations at 1280 and 843 MHz from the Giant Metrewave Radio Telescope and Molonglo Survey archive, respectively. A combination of NIR and MIR data is used to identify 7 Class I and 133 Class II sources in the region. Spectral energy distribution (SED) analysis of selected sources reveals a 9.6 M ⊙ high-mass source embedded in nebulosity. However, Lyman continuum luminosity calculation using radio emission – which shows a compact H ii region – indicates the spectral type of the ionizing source to be earlier than B0-O9.5. Free–free emission SED modelling yields the electron density as 138 cm −3 , and thus the mass of the ionized hydrogen as ∼16.4 M ⊙ . Thermal dust emission modelling, using the FIR data from Herschel and performing modified blackbody fits, helped us construct the temperature and column density maps of the region, which show peak values of 30 K and 3.3 × 10 22 cm −2 , respectively. The column density maps reveal an A V  > 20 mag extinction associated with the nebular emission, and weak filamentary structures connecting dense clumps. The clump associated with this IRAS object is found to have dimensions of ∼ 1.1 pc × 0.8 pc, and a mass of 1023 M ⊙ .

A MULTI-WAVELENGTH STUDY OF STAR FORMATION ACTIVITY IN THE S235 COMPLEX

We have carried out an extensive multi-wavelength study to investigate the star formation process in the S235 complex. The S235 complex has a sphere-like shell appearance at wavelengths longer than 2

NGC 7538: multiwavelength study of stellar cluster regions associated with IRS 1–3 and IRS 9 sources

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Star formation around the mid-infrared bubble CN 148

m and harbors an O9.5V type star approximately at its center. Near-infrared extinction map traces eight subregions (having A

Sh2-138: physical environment around a small cluster of massive stars

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THE W40 REGION IN THE GOULD BELT: AN EMBEDDED CLUSTER AND H II REGION AT THE JUNCTION OF FILAMENTS

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The physical environment of the massive star-forming region W42

8 mag), and five of them appear to be distributed in an almost regularly spaced manner along the sphere-like shell surrounding the ionized emission. This picture is also supported by the integrated

STAR FORMATION ACTIVITY IN THE GALACTIC H II REGION Sh2-297

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Reappearance of Mcneil's nebula (V1647 Orionis) and its outburst environment

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