Affiliation:
1. Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India
Abstract
ABSTRACT
We present multiscale and multiwavelength data of the Galactic H ii region G25.4−0.14 (hereafter G25.4NW, distance ∼5.7 kpc). The SHARC-II 350-μm continuum map displays a hub-filament configuration containing five parsec-scale filaments and a central compact hub. Through the 5-GHz radio continuum map, four ionized clumps (i.e. Ia–Id) are identified towards the central hub, and are powered by massive OB-stars. The Herschel temperature map depicts the warm dust emission (i.e. T$_{\rm d}\, \sim$23–39 K) towards the hub. High-resolution Atacama Large Millimeter/submillimeter Array (ALMA) 1.3-mm continuum map (resolution ∼0.82 × 0.58 arcsec2) reveals three cores (c1–c3; mass ∼80–130 M⊙) towards the ionized clumps Ia, and another one (c4; mass ∼70 M⊙) towards the ionized clump Ib. A compact near-infrared (NIR) emission feature (extent ∼0.2 pc) is investigated towards the ionized clump Ia excited by an O8V-type star, and contains at least three embedded K-band stars. In the direction of the ionized clump Ia, the ALMA map also shows an elongated feature (extent ∼0.2 pc) hosting the cores c1–c3. All these findings together illustrate the existence of a small cluster of massive stars in the central hub. Considering the detection of the hub-filament morphology and the spatial locations of the mm cores, a global non-isotropic collapse (GNIC) scenario appears to be applicable in G25.4NW, which includes the basic ingredients of the global hierarchical collapse and clump-fed accretion models. Overall, the GNIC scenario explains the birth of massive stars in G25.4NW.
Funder
Indian Space Research Organisation
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
6 articles.
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