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

Mallick, K. K.; Ojha, D. K.; Samal, M. R.; Pandey, A. K.; Bhatt, B. C.; Ghosh, S. K.; Dewangan, L. K.; Tamura, Motohide

doi:10.1088/0004-637x/759/1/48

Cited by 27 publications

(29 citation statements)

References 67 publications

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“…Note that we have corrected only the foreground extinc- tion for isochrones, however the extinction due to local clouds and circumstellar material can also cause apparent spread in age and mass. Similar age and mass spreads were reported in other starforming regions like Sh2-297 (Mallick et al 2012), young open cluster Stock 8 (Jose et al 2008), and NGC 1893 (Sharma et al 2007). However, determining the ages of PMS stars is a rather difficult task and the age-spread obtained in CM-D can be explained due to variable extinction towards the individual sources, photometric variability due to presence of disk/accretion, spatially unresolved binaries, and scattered light from the disk with large inclination (Hillenbrand, Bauermeister & White 2008;Soderblom et al 2014).…”

Section: Mass and Age Spread From Optical V/v-i Colour-magnitude Diagramsupporting

confidence: 84%

“…At meter wavelengths, a large amount of radiation comes from the Galactic plane which increases the effective antennae temperature. Hence, it was important to correct both 610 and 1280 MHz images for system temperature (see Omar, Chengalur & Roshi 2002;Mallick et al 2012;Vig et al 2014). It was done by rescaling both the images by a correction factor of (T f req + Tsys)/Tsys, where Tsys is the system temperature obtained from GMRT Web site, and T f req is the sky temperature at the observed frequency (i.e., 610 and 1280 MHz) towards the source obtained using the interpolated value from the sky temperature map of Haslam et al (1982) at 408 MHz.…”

Section: Radio Continuum Observationsmentioning

confidence: 99%

“…The sources in the 'F' region are generally considered as evolved field stars or Class III YSOs (Weak-line T Tauri Stars). The sources in the 'T' region are mainly Class II YSOs (CTTS; Lada & Adams 1992) with a large NIR excess and reddened early type MS stars with excess emission in the K-band (Mallick et al 2012). The sources in the 'P' region are Class I YSOs with circumstellar envelopes.…”

Section: Nir Colour-colour Diagrammentioning

confidence: 99%

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

Baug

Ojha

Dewangan

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a multi-wavelength study of the Sh2-138, a Galactic compact H II region. The data comprise of optical and near-infrared (NIR) photometric and spectroscopic observations from the 2-m Himalayan Chandra Telescope, radio observations from the Giant Metrewave Radio Telescope (GMRT), and archival data covering radio through NIR wavelengths. A total of 10 Class I and 54 Class II young stellar objects (YSOs) are identified in a 4.′ 6×4. ′ 6 area of the Sh2-138 region. Five compact ionized clumps, with four lacking of any optical or NIR counterparts, are identified using the 1280 MHz radio map, and correspond to sources with spectral type earlier than B0.5. Free-free emission spectral energy distribution fitting of the central compact H II region yields an electron density of ∼2250±400 cm −3 . With the aid of a wide range of spectra, from 0.5-15 µm, the central brightest source -previously hypothesised to be the main ionizing source -is characterized as a Herbig Be type star. At large scale (15′ ), the Herschel images (70-500 µm) and the nearest neighbour analysis of YSOs suggest the formation of an isolated cluster at the junction of filaments. Furthermore, using a greybody fit to the dust spectrum, the cluster is found to be associated with the highest column density (∼3×10 22 cm −2 ) and high temperature (∼35 K) regime, as well as with the radio continuum emission. The mass of the central clump seen in the column density map is estimated to be ∼3770 M ⊙ .

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Section: Mass and Age Spread From Optical V/v-i Colour-magnitude Diagramsupporting

confidence: 84%

Section: Radio Continuum Observationsmentioning

confidence: 99%

Section: Nir Colour-colour Diagrammentioning

confidence: 99%

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

Baug

Ojha

Dewangan

et al. 2015

Mon. Not. R. Astron. Soc.

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“…This is done by obtaining the sky temperature map of Haslam et al (1982) at 408 MHz, and by rescaling the image by a scaling factor which is just the ratio of the system temperature toward the target source and the flux calibrator. Details of the procedure have been discussed in Mallick et al (2012). Fig.…”

Section: Radio Continuum Observationsmentioning

confidence: 99%

A multiwavelength investigation of the H ii region S311: young stellar population and star formation

Yadav

Pandey

Sharma

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a multiwavelength investigation of the young stellar population and star formation activities around the H ii region Sharpless 311. Using our deep near-infrared observations and archival Spitzer-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of ∼86 arcmin 2 . The YSOs sample include 8 Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSOs sample is estimated to be 1.0 M . The ages and masses of the majority of the candidate YSOs are estimated to be in the range of ∼0.1−5 Myr and ∼0.3−6 M , respectively. The 8 µm image of S311 displays an approximately spherical cavity around the ionizing source which is possibly created due to the expansion of the H ii region. The spatial distribution of the candidate YSOs reveals that a significant number of them are distributed systematically along the 8 µm emission with a majority clustered around the eastern border of the H ii region. Four clumps/compact H ii regions are detected in the radio continuum observations at 1280 MHz, which might have been formed during the expansion of the H ii region. The estimated dynamical age of the region, main-sequence lifetime of the ionizing source, the spatial distribution and ages of the candidate YSOs indicate triggered star formation in the complex.

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“…Since we know that the photometric error is larger at the fainter end of the CMD, the shape of the cut-off line at the fainter end is adjusted accordingly. All the stars having a color "(H − K) 0 − σ (H−K) 0 " greater than the red cut-off line might have an excess emission in the K band and thus can reasonably be considered to be probable YSOs (see also Mallick et al 2012). While this sample is dominated by YSOs, it may also contain the following types of contaminations: variable stars, dusty asymptotic giant branch (AGB) stars, unresolved planetary nebulae, and background galaxies (Robitaille et al 2008;Povich et al 2011).…”

Section: On the Basis Of Ir Excessmentioning

confidence: 99%

Investigation of the stellar content in the western part of the Carina nebula

Kumar¹,

Sharma²,

Manfroid³

et al. 2014

A&A

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Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. Aims. To investigate this process, we generated a new catalog of the pre-main-sequence stars in the Carina west (CrW) region and studied their nature and spatial distribution. We also determined various parameters (reddening, reddening law, age, mass), which are used further to estimate the initial mass function and K-band luminosity function for the region under study. Methods. We obtained deep UBVRI Hα photometric data of the field situated to the west of the main Carina nebula and centered on WR 22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data sets from Chandra, XMM-Newton and 2MASS surveys were used for the present study. Different sets of color-color and color-magnitude diagrams are used to determine reddening for the region and to identify young stellar objects (YSOs) and estimate their age and mass. Results. Our spectroscopic results indicate that the majority of the X-ray sources are late spectral type stars. The region shows a large amount of differential reddening with minimum and maximum values of E(B − V) as 0.25 and 1.1 mag, respectively. Our analysis reveals that the total-to-selective absorption ratio R V is ∼3.7 ± 0.1, suggesting an abnormal grain size in the observed region. We identified 467 YSOs and studied their characteristics. The ages and masses of the 241 optically identified YSOs range from ∼0.1 to 10 Myr and ∼0.3 to 4.8 M , respectively. However, the majority of them are younger than 1 Myr and have masses below 2 M . The high mass star WR 22 does not seem to have contributed to the formation of YSOs in the CrW region. The initial mass function slope, Γ, in this region is found to be −1.13 ± 0.20 in the mass range of 0.5 < M/M < 4.8. The K-band luminosity function slope (α) is also estimated as 0.31 ± 0.01. We also performed minimum spanning tree analysis of the YSOs in this region, which reveals that there are at least ten YSO cores associated with the molecular cloud, and that leads to an average core radius of 0.43 pc and a median branch length of 0.28 pc.

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

Cited by 27 publications

References 67 publications

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

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

A multiwavelength investigation of the H ii region S311: young stellar population and star formation

Investigation of the stellar content in the western part of the Carina nebula

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