A MULTIWAVELENGTH STUDY OF STAR FORMATION IN THE VICINITY OF GALACTIC H II REGION Sh 2-100

Samal, M. R.; Pandey, A. K.; Ojha, D. K.; Ghosh, S. K.; Kulkarni, V. K.; Kusakabe, Nobuhiko; Tamura, Motohide; Bhatt, B. C.; Sagar, Ram

doi:10.1088/0004-637x/714/2/1015

Cited by 26 publications

(52 citation statements)

References 88 publications

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“…The 70 μm flux upper limit is assigned only to those sources that are not detected in the 70 μm observed area. For sources that are located outside the 70 μm observed area and not detected in 65 μm band, we assigned the minimum 65 μm flux obtained for the point sources observed in the region from the AKARI survey; iii) we scaled the SED models to the distance of the filament (i.e., 2.5 ± 0.2 kpc; Chavarría et al 2008) and allowed a maximum A V value determined by tracing back the YSOs' current location on J vs. J−H or K vs. H−K or K vs. K− [3.4] diagram to the intrinsic dwarf locus along the reddening vector (see, e.g., Samal et al 2010). Figure 9 shows the SEDs of 38 sources that satisfy our five data-point flux criteria.…”

Section: Properties Of the Ysosmentioning

confidence: 99%

Star formation in the filament of S254-S258 OB complex: a cluster in the process of being created

Samal

Ojha

Jose

et al. 2015

A&A

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Infrared dark clouds are ideal laboratories for studying the initial processes of high-mass star and star-cluster formation. We investigated the star formation activity of an unexplored filamentary dark cloud (size ∼5.7 pc × 1.9 pc), which itself is part of a large filament (∼20 pc) located in the S254-S258 OB complex at a distance of 2.5 kpc. Using Multi-band Imaging Photometer (MIPS) Spitzer 24 μm data, we uncovered 49 sources with signal-to-noise ratios greater than 5. We identified 45 sources as candidate young stellar objects (YSOs) of Class I, flat-spectrum, and Class II natures. Additional 17 candidate YSOs (9 Class I and 8 Class II) are also identified using JHK and Wide-field Infrared Survey Explorer (WISE) photometry. We find that the protostar-to-Class II sources ratio (∼2) and the protostar fraction (∼70%) of the region are high. Comparison of the protostar fraction to other young clusters suggests that the star formation in the dark cloud possibly started only 1 Myr ago. Combining the near-infrared photometry of the YSO candidates with the theoretical evolutionary models, we infer that most of the candidate YSOs formed in the dark cloud are low-mass (<2 M ). We examine the spatial distribution of the YSOs and find that majority of them are linearly aligned along the highest column density line (N(H 2 ) ∼ 1 × 10 22 cm −2 ) of the dark cloud along its long axis at the mean nearest-neighbour separation of ∼0.2 pc. Using the observed properties of the YSOs, physical conditions of the cloud and a simple cylindrical model, we explore the possible star formation process of this filamentary dark cloud and suggest that gravitational fragmentation within the filament should have played a dominant role in the formation of the YSOs. From the total mass of the YSOs, the gaseous mass associated with the dark cloud, and the surrounding environment, we infer that the region is presently forming stars at an efficiency of ∼3% and a rate ∼30 M Myr −1 , and it may emerge in a richer cluster.

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Section: Properties Of the Ysosmentioning

confidence: 99%

Star formation in the filament of S254-S258 OB complex: a cluster in the process of being created

Samal

Ojha

Jose

et al. 2015

A&A

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“…We used 22 µm data as upper-limit owing to its large beam (∼22 arcsec) and crowded nature of the field. While fitting models we scaled the SED models to the distance of the cluster (i.e., 2.6 ± 0.4 kpc) and allowed a maximum AV value determined by tracing back the YSOs current location on J/J − H diagram to the intrinsic dwarf locus along the reddening vector (see e.g., Samal et al 2010), where the minimum extinction adopted as 1.5 mag, which is the foreground extinction towards the direction of cluster. Fig.…”

Section: Spectral Energy Distributionmentioning

confidence: 99%

Variable stars in young open star cluster NGC 7380

Lata¹,

Pandey²,

Panwar³

et al. 2015

Mon. Not. R. Astron. Soc.

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We present time series photometry of 57 variable stars in the cluster region NGC 7380. The association of these variable stars to the cluster NGC 7380 has been established on the basis of two colour diagrams and colour-magnitude diagrams. Seventeen stars are found to be main-sequence variables, which are mainly B type stars and are classified as slowly pulsating B stars, β Cep or δ Scuti stars. Some of them may belong to new class variables as discussed by Mowlavi et al. (2013) and Lata et al. (2014). Present sample also contains 14 pre-main-sequence stars, whose ages and masses are found to be mostly 5 Myr and range 0.60 M/M ⊙ 2.30 and hence should be T-Tauri stars. About half of the weak line T-Tauri stars are found to be fast rotators with a period of 2 days as compared to the classical T-Tauri stars. Some of the variables belong to the field star population.

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“…First, we identified all the luminous sources inside the bubble earlier than B2V stars. We followed the same prescription as described in Samal et al (2010), of rejecting the most-likely giants and foreground sources based on J vs. J − H and J − H vs. H − K diagrams. After these eliminations we remain with a massive O-type star located at the center of the bubble close to the strong 24 μm emission.…”

Section: Ionizing Source(s) Of Sh2-90mentioning

confidence: 99%

The molecular complex associated with the Galactic H II region Sh2-90: a possible site of triggered star formation

Samal

Zavagno

Deharveng

et al. 2014

A&A

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Aims. We investigate the star formation activity in the molecular complex associated with the Galactic H ii region Sh2-90.Methods. We obtain the distribution of the ionized and cold neutral gas using radio-continuum and Herschel observations. We use near-infrared and Spitzer data to investigate the stellar content of the complex. We discuss the evolutionary status of embedded massive young stellar objects (MYSOs) using their spectral energy distribution.Results. The Sh2-90 region presents a bubble morphology in the mid-infrared. Radio observations suggest it is an evolved H ii region with an electron density ∼144 cm −3 , emission measure ∼6.7 × 10 4 cm −6 pc and an ionized mass ∼55 M . From Herschel and CO (J = 3−2) observations we found that the H ii region is part of an elongated extended molecular cloud (H 2 column density ≥3 × 10 21 cm −2 and dust temperature 18−27 K) of total mass ≥1 × 10 4 M . We identify the ionizing cluster of Sh2-90, the main exciting star being an O8-O9 V star. Five cold dust clumps, four mid-IR blobs around B stars, and a compact H ii region are found at the edge of the bubble. The velocity information derived from CO data cubes suggest that most of them are associated with the Sh2-90 region. One hundred and twenty-nine low mass (≤3 M ) YSOs have been identified, and they are found to be distributed mostly in the regions of high column density. Four candidate Class 0/I MYSOs have been found. We suggest that multi-generation star formation is present in the complex. From evidence of interaction, time scales involved, and evolutionary status of stellar/protostellar sources, we argue that the star formation at the edges of Sh2-90 might have been triggered. However, several young sources in this complex are probably formed by some other processes.

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A MULTIWAVELENGTH STUDY OF STAR FORMATION IN THE VICINITY OF GALACTIC H II REGION Sh 2-100

Cited by 26 publications

References 88 publications

Star formation in the filament of S254-S258 OB complex: a cluster in the process of being created

Star formation in the filament of S254-S258 OB complex: a cluster in the process of being created

Variable stars in young open star cluster NGC 7380

The molecular complex associated with the Galactic H II region Sh2-90: a possible site of triggered star formation

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