Mass, Stability and Tidal Budget for the Kepler-1625 b Exomoon Candidate

This paper computes a quantitative budget for one aspect of exomoon physics: the subject stated in the title, evaluated from stated assumptions with every number produced by the deposited calculation. Headline results are hill_radius_Rp = 179; moon_separation_fraction_Hill = 0.22; prograde_stable = True; moon_period_days = 17.4; mass_ratio_percent = 1.80; moon_transit_depth_ppm = 1253. The Neptune-sized companion proposed for the long-period giant Kepler-1625 b remains the most discussed exomoon candidate, and also the most contested, with independent reductions of the same photometry reaching different conclusions about the depth and even the presence of the moon-like dip. Whatever the outcome of that photometric dispute, the candidate can be tested on physical grounds that do The results are compared with published Solar System values and with the constraints attached to reported exomoon candidates where those apply, and the conditions under which the computed budget would change are stated explicitly. Computed from stated assumptions, not measured.