The molecular cloud S242: physical environment and star formation activities

Abstract

We present a multi-wavelength study to probe the star formation (SF) processes on a larger scale (~1.05 deg x 0.56 deg) around the S242 site. The S242 molecular cloud is depicted in a velocity range from -3.25 to 4.55 km/s and has spatially elongated appearance. Based on the virial analysis, the cloud is prone to gravitational collapse. The cloud harbors an elongated filamentary structure (EFS; length ~25 pc) evident in the Herschel column density map and the EFS has an observed mass per unit length of ~200 M_sun/pc exceeding the critical value of ~16 M_sun/pc (at T = 10 K). The EFS contains a chain of Herschel clumps (M_clump ~150 to 1020 M_sun), revealing the evidence of fragmentation along its length. The most massive clumps are observed at both the EFS ends, while the S242 HII region is located at one EFS end. Based on the radio continuum maps at 1.28 and 1.4 GHz, the S242 HII region is ionized by a B0.5V - B0V type star and has a dynamical age of ~0.5 Myr. The photometric 1 - 5 microns data analysis of point-like sources traces young stellar objects (YSOs) toward the EFS and the clusters of YSOs are exclusively found at both the EFS ends, revealing the SF activities. Considering the spatial presence of massive clumps and YSO clusters at both the EFS ends, the observed results are consistent with the prediction of a SF scenario of the end-dominated collapse driven by the higher accelerations of gas.

19 pages, 10 figures, 1 table, Accepted for publication in The Astrophysical Journal

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Filamentary structure of star-forming complexes
• Cooling, Gravity and Geometry: Flow-driven Massive Core Formation
• Aspect Ratio Dependence of the Free-Fall Time for Non-Spherical Symmetries
• Smoothed Particle Hydrodynamics simulations of expanding HII regions. I. Numerical methods and tests
• Cluster Formation Triggered by Filament Collisions in Serpens South
• Multi-wavelength study of the star-formation in the S237 H II region
• Study of morphology and stellar content of the Galactic HII region IRAS 16148-5011

Cited by in corpus (9)

• Observational signatures of end-dominated collapse in the S242 filamentary structure
• Edge collapse and subsequent longitudinal accretion in Filament S242
• Star-forming sites IC 446 and IC 447: an outcome of end-dominated collapse of Monoceros R1 filament
• Simultaneous evidence of edge collapse and hub-filament configurations: A rare case study of a Giant Molecular Filament G45.3+0.1
• Evidence of interacting elongated filaments in the star-forming site AFGL 5142
• Lynds Bright Nebulae: Sites of possible twisted filaments and ongoing star formation
• Sequential Star Formation in the filamentary structures of Planck Galactic cold clump G181.84+0.31
• Molecular Clouds Associated with {H \small{II}} regions and Candidates within l = 106.65${}^{\circ }$ to 109.50${}^{\circ }$ and b = $-$1.85${}^{\circ }$ to 0.95${}^{\circ }$
• Kronberger 55: A Candidate for End-dominated Collapse Scenario