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arXiv · 2601.16439

Star formation outside galaxies undergoing gravitational and hydrodynamic interactions: Dust attenuation and the star formation rate

Geethika Santhosh·Rakhi R·Koshy George·Bianca M. Poggianti·Smitha Subramanian·Kavila Indulekha
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Abstract

Galaxies undergo perturbations, either gravitational or hydrodynamic in origin, which can generate extragalactic structures such as rings and tails, where in situ star formation may take place. We selected a sample consisting of JO201 and JW100, undergoing ram-pressure stripping, and NGC 5291 and NGC 7252, formed through gravitational interactions, to investigate how different perturbation mechanisms influence dust content and star formation in extragalactic features. In both cases, star formation can be observed outside the main disks of the galaxies. We present new results of dust attenuation for JO201 and JW100, while for NGC 5291 and NGC 7252 we use results from our previous study, based on high-resolution observations obtained with the Ultraviolet Imaging Telescope onboard AstroSat. Dust attenuation is determined from the ultraviolet continuum slope ($β$) calculated using the FUV-NUV colour, and the star formation rates of the star-forming knots are corrected accordingly. It is seen that dust attenuation and dust-corrected SFR densities of the knots in the ram-pressure stripped tails of JO201 and JW100 are comparable to those in the collisional ring of the NGC 5291 system and the tidal tails of the NGC 7252 system. We conclude that, though the formation scenarios of the tails of JO201 and JW100, the NGC 5291 ring, and the NGC 7252 tails are different, their dust content and star formation activity are notably similar.

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Geethika Santhosh, Rakhi R, Koshy George, Bianca M. Poggianti, Smitha Subramanian, Kavila Indulekha. 2026-03-06. Star formation outside galaxies undergoing gravitational and hydrodynamic interactions: Dust attenuation and the star formation rate. https://doi.org/10.1017/pasa.2026.10154

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