Comparison of the SFR (top) and R_H I/R_optical (bottom) in the three scenarios. The top panel shows the evolution of the SFR over time for the fly-by (red), mixed merger (light blue), and wet merger (blue) simulations. We define the first pericentric passage of the two galaxies in the merger scenario as the zeropoint in time. The dashed black lines represent the values from the isolated disk simulation. The bottom panel shows the measured R_H I/R_optical values for observations of VCC 693 (left) and for the simulations (right three points: pre-merger, mixed merger, and wet merger). The optical radius of observations and typical value of late-type galaxies (dashed black line) are measured from the 25 mag arcsec⁻² isophote of the optical B-band image, while in the simulations, we adopt the optical radius corresponding to a pre-merger R_H I/R_optical of 1.7 as the reference (log Σ_star = 0.48 M_⊙ pc⁻²), with error bars indicating a ±0.2 dex range in log Σ_star.