We investigate the relationships between infrared excess (IRX=L ₈ₑ/L ₔₕ) and Balmer decrement (Hα/ Hβ) as indicators of dust attenuation for 609 {H\, { II}} regions at scales of 50-200 pc in NGC 628, utilizing data from AstroSat, James Webb Space Telescope (JWST) and Multi Unit Spectroscopic Explorer (MUSE). Our findings indicate that about three fifths of the sample {H\, { II}} regions reside within the regime occupied by local star-forming galaxies (SFGs) along the dust attenuation correlation described by their corresponding color excess parameters E (B-V) ₈ₑₗ = 0. 51\, E (B-V) ₇α/{ Hβ}. Nearly 27\% of the sample exhibits E (B-V) ₈ₑₗ> E (B-V) ₇α/{ Hβ}, while a small fraction (13\%) displays significantly lower E (B-V) ₈ₑₗ compared to E (B-V) ₇α/{ Hβ}. These results suggest that the correlation between the two dust attenuation indicators no longer holds for spatially resolved {H\, { II}} regions. Furthermore, the ratio of E (B-V) ₈ₑₗ to E (B-V) ₇α/{ Hβ} remains unaffected by various physical parameters of the {H\, { II}} regions, including star formation rate (SFR), SFR surface density, infrared luminosity (L ₈ₑ), L ₈ₑ surface density, stellar mass, gas-phase metallicity, circularized radius, and the distance to galactic center. We argue that the ratio is primarily influenced by the evolution of surrounding interstellar medium (ISM) of the star-forming regions, transitioning from an early dense and thick phase to the late blown-away stage.
Qiao et al. (Thu,) studied this question.