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

Baug, Tapas; Ojha, D. K.; Dewangan, L. K.; Ninan, Joe P.; Bhatt, B. C.; Ghosh, S. K.; Mallick, K. K.

doi:10.1093/mnras/stv2269

Cited by 29 publications

(36 citation statements)

References 77 publications

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“…(e.g. Myers 2009;Schneider et al 2012;Peretto et al 2013;Dewangan et al 2015b;Baug et al 2015). In the simulations of Dale & Bonnell (2011), a similar result was reported.…”

Section: Discussionsupporting

confidence: 77%

Hub-filament System in IRAS 05480+2545: Young Stellar Cluster and 6.7 GHz Methanol Maser

Dewangan

Ojha

Baug

2017

ApJ

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To probe the star formation (SF) process, we present a multi-wavelength study of IRAS 05480+2545 (hereafter I05480+2545). Analysis of Herschel data reveals a massive clump (M clump ∼1875 M ; peak N(H 2 ) ∼4.8 × 10 22 cm −2 ; A V ∼51 mag) containing the 6.7 GHz methanol maser and I05480+2545, which is also depicted in a temperature range of 18-26 K. Several noticeable parsec-scale filaments are detected in the Herschel 250 µm image and seem to be radially directed to the massive clump. It resembles more of a "hub-filament" system. Deeply embedded young stellar objects (YSOs) have been identified using the 1-5 µm photometric data, and a significant fraction of YSOs and their clustering are spatially found toward the massive clump, revealing the intense SF activities. An infrared counterpart (IRc) of the maser is investigated in the Spitzer 3.6-4.5 µm images. The IRc does not appear point-like source and is most likely associated with the molecular outflow. Based on the 1.4 GHz and Hα continuum images, the ionized emission is absent toward the IRc, indicating that the massive clump harbors an early phase of massive protostar before the onset of an ultracompact H ii region. Together, the I05480+2545 is embedded in a very similar "hub-filament" system to those seen in Rosette Molecular Cloud. The outcome of the present work indicates the role of filaments in the formation of the massive star-forming clump and cluster of YSOs, which might help channel material to the central hub configuration and the clump/core.

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“…(e.g. Myers 2009;Schneider et al 2012;Peretto et al 2013;Dewangan et al 2015b;Baug et al 2015). In the simulations of Dale & Bonnell (2011), a similar result was reported.…”

Section: Discussionsupporting

confidence: 77%

Hub-filament System in IRAS 05480+2545: Young Stellar Cluster and 6.7 GHz Methanol Maser

Dewangan

Ojha

Baug

2017

ApJ

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“…(e.g. Myers 2009;Schneider et al 2012;Peretto et al 2013;Dewangan et al 2015;Baug et al 2015;Dewangan et al 2017b). This particular result favours the role of filaments in the formation of star-forming clumps and clusters of YSOs.…”

Section: Clustering Of Ysosmentioning

confidence: 99%

Embedded Filaments in IRAS 05463+2652: Early Stage of Fragmentation and Star Formation Activities

Dewangan¹,

Devaraj²,

Baug³

et al. 2017

ApJ

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We present a multi-wavelength data analysis of IRAS 05463+2652 (hereafter I05463+2652) to study star formation mechanisms. A shell-like structure around I05463+2652 is evident in the Herschel column density map, which is not associated with any ionized emission. Based on the Herschel submillimeter images, several parsec-scale filaments (including two elongated filaments, "s-fl" and "nw-fl" having lengths of ∼6.4 and ∼8.8 pc, respectively) are investigated in I05463+2652 site. Herschel temperature map depicts all these features in a temperature range of ∼11-13 K. 39 clumps are identified and have masses between ∼70-945 M . A majority of clumps (having M clump 300 M ) are distributed toward the shell-like structure. 175 young stellar objects (YSOs) are selected using the photometric 1-5 µm data and a majority of these YSOs are distributed toward the four areas of high column density ( 5 × 10 21 cm −2 ; A V ∼5.3 mag) in the shell-like structure, where massive clumps and a spatial association with filament(s) are also observed. The knowledge of observed masses per unit length of elongated filaments and critical mass length reveals that they are supercritical. The filament "nw-fl" is fragmented into five clumps (having M clump ∼100-545 M ) and contains noticeable YSOs, while the other filament "s-fl" is fragmented into two clumps (having M clump ∼ 170-215 M ) without YSOs. Together, these observational results favor the role of filaments in star formation process in I05480+2545. This study also reveals the filament "s-fl", containing two starless clumps, at an early stage of fragmentation.

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“…A few bias frames and Fe-Ne calibration lamp spectra were also taken for the bias subtraction and calibration of the observed spectrum. Following the standard reduction procedures, the observed optical spectrum was extracted using a semi-automated pipeline written in PyRAF (Ninan et al 2014;Baug et al 2015). The signal-to-noise ratio (S/N) of the optical spectrum is achieved to be 45.…”

Section: Optical Spectrummentioning

confidence: 99%

“…A separate telluric standard (α Aql) was also observed for telluric correction. Adopting the standard reduction procedures, the observed spectra were reduced using a semi-automated pipeline written in PyRAF (Ninan et al 2014;Baug et al 2015). Finally, the reduced spectra at H and K bands were flux-calibrated using the Two Micron All Sky Survey (2MASS; resolution ∼2.…”

Section: Near-infrared Spectramentioning

confidence: 99%

Star-Formation Activity in the Neighborhood of W–r 1503-160l Star in the Mid-Infrared Bubble N46

Dewangan

Baug

Ojha

et al. 2016

ApJ

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In order to investigate star formation (SF) processes in extreme environments, we have carried out a multi-wavelength analysis of the mid-infrared bubble N46, which hosts a WN7 Wolf-Rayet (W-R) star. We have used 13 CO line data to trace an expanding shell surrounding the W-R star containing about five condensations within the molecular cloud associated with the bubble. The W-R star is associated with a powerful stellar wind having a mechanical luminosity of ∼4 × 10 37 ergs s −1 . A deviation of the H-band starlight mean polarization angles around the bubble has also been traced, indicating the impact of stellar wind on the surroundings. The Herschel temperature map shows a temperature range of ∼18-24 K toward the five molecular condensations. The photometric analysis reveals that these condensations are associated with the identified clusters of young stellar objects, revealing ongoing SF process. The densest among these five condensations (peak N(H 2 ) ∼9.2 × 10 22 cm −2 and A V ∼98 mag) is associated with a 6.7 GHz methanol maser, an infrared dark cloud, and the CO outflow, tracing active massive SF within it. At least five compact radio sources (crss) are physically linked with the edges of the bubble and each of them is consistent with the radio spectral class of a B0V-B0.5V type star. The ages of the individual infrared counterparts of three crss (∼1-2 Myr) and a typical age of WN7 W-R star (∼4 Myr) indicate that the SF activities around the bubble are influenced by the feedback of the W-R star.

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

Cited by 29 publications

References 77 publications

Hub-filament System in IRAS 05480+2545: Young Stellar Cluster and 6.7 GHz Methanol Maser

Hub-filament System in IRAS 05480+2545: Young Stellar Cluster and 6.7 GHz Methanol Maser

Embedded Filaments in IRAS 05463+2652: Early Stage of Fragmentation and Star Formation Activities

Star-Formation Activity in the Neighborhood of W–r 1503-160l Star in the Mid-Infrared Bubble N46

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