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Author Samal, M. R. ♦ Pandey, A. K. ♦ Ojha, D. K. ♦ Ghosh, S. K. ♦ Kulkarni, V. K. ♦ Bhatt, B. C.
Source Aryabhatta Research Institute of Observational Sciences (ARIES)
Content type Text
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Physics
Subject Keyword Dust ♦ Extinction — galaxies ♦ Star clusters — H II regions — infrared ♦ Multiwavelength ♦ Individual (S294) — radio continuum ♦ ISM — stars ♦ Formation
Abstract We present the observational results of Galactic H II region Sh 2-294, using optical photometry, narrowbandimaging, and radio continuum mapping at 1280 MHz, together with archival data from the 2MASS, MSX, and IRASsurveys. The stellar surface density profile indicates that the radius of the cluster associated with the Sh 2-294 regionis ~2.3' . We estimate the minimum reddening E(B-V)=1.35 mag and a distance of 4.8 ± 0.2 kpc to the region.The ratio of the total to the selective extinction (Rᵥ) is found to be 3.8 ± 0.1, indicates an anomalous reddening law forthe dust inside the cluster region. We identified the ionizing source of the H II region, and spectral type estimates areconsistent with a star of spectral type ~B0 V. The 2MASS JHKs images reveal a partially embedded cluster associatedwith the ionizing source along with a small cluster towards the eastern border of Sh 2-294. The radio continuum and H images show the ionization front along the direction of the small cluster. An arc-shaped diffuse molecular hydrogenemission and a half-ring of dust emission are also seen in the direction of the ionization front at 2.12 and 8 µm(MSX ),respectively. Self-consistent radiative transfer model of mid- to far-infrared continuum emission detected near smallcluster is in good agreement with the observed spectral energy distribution of a B1.5 ZAMS star. The morphologicalcorrelation between the ionized and molecular gas, along with probable timescale involved between the ionizing star,evolution of H II region, and small cluster, indicates that the star formation activity observed at the border is probablytriggered by the expansion of H ii region.
Part of series apj671-555
Educational Use Research
Education Level UG and PG
Learning Resource Type Article