Multi-scale view of the S-shaped high-mass star-forming filament IRAS 19074+0752 observed as part of the INFANT survey

It is generally accepted that high-mass stars form through a hierarchical, multi-scale fragmentation process that range from molecular clouds down to individual protostars, involving intermediate scales such as filaments. However, a comprehensive understanding of this process remains limited due to the lack of high-resolution, multi-scale observational studies that would simultaneously probe the physical conditions across the full hierarchy of star-forming structures. We aim to understand a coherent picture of the physical processes connecting filament formation, fragmentation, and dynamical scenario of high-mass star formation in the IRAS,19074+0752 (hereafter I19074) region. Primarily using new 1.3,mm continuum mosaicked observations, as part of the ALMA-INFANT survey, we analyzed the S-shaped filamentary cloud I19074 at a ∼6000,AU resolution. Leveraging the multi-scale information, we investigated the filament and clump fragmentation properties, such as core separations and masses. ALMA 1.3,mm dust continuum emission reveals that the S-shaped filament consists of two physically connected components: a southern (Fs) and a northern (Fn) segment. Fn is associated with an infrared (IR)-bright HII region, while Fs appears IR-dark. The total filament length is ∼ 2.8,pc, with Fn and Fs spanning ∼ 1.0,pc and ∼ 1.8,pc, respectively. Their masses are ∼ 250--910,M_⊙, while their line masses (∼250--360,M_⊙ pc ) exceed the critical value for turbulence support, indicating they are gravitationally bound. The S-shaped morphology likely results from the expansion of the HII region, which swept up and compressed the northern part of the pre-existing filament into an arc-like structure in Fn; meanwhile, Fs retained a more linear form due to its greater distance from the ionized gas. Accordingly, a hybrid scenario could be responsible for Fn formation, which would combine the compression of a pre-existing filament by the HII region with fresh gas accumulation into the shocked-compression layer. We extracted 26 dense cores from 1.3,mm emission with masses between 1.0 and 22.9,M_⊙, with most (92%) being gravitationally bound (α_ ̊m vir łeq 2). The core separations lack periodicity; instead, four core groups define four clumps (clumps,1–4) with masses of 110--620,M_⊙. In the Fs segment, clump,1 at its southern end could be a product of edge fragmentation, while Fn exhibits hierarchical fragmentation modes: the filamentary mode responsible for clump formation within Fn and the spherical Jeans-like mode for core formation within clumps. Hierarchical fragmentation mechanisms are identified as shocked turbulence-driven within Fn and gravity-driven inside the clumps. Most cores have high mass surface densities of Σ_ ̊m core ≥ 1 but with no robust identification of high-mass prestellar candidates. This favors dynamical clump-fed accretion-type over core-fed accretion-type models for high-mass star formation in I19074. ii region, with the shocked-shell fragmentation mechanism in Fn and edge fragmentation in Fs serving as pathways for producing massive, star-forming clumps. Both mechanisms contribute to high-mass star formation via a dynamical clump-fed accretion process within their respective filamentary segments.