2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/95064We investigate observational constraints on the variable Chaplygin gas model from the gold sample of type Ia supernova data and the recent measurements of the X-ray gas mass fractions in galaxy clusters. Combining these databases, we obtain a tight constraint on the two model parameters. Our results indicate that the original Chaplygin gas model is ruled out by the data at 99.7% confidence level.9 pages, 5 figures, LaTeX2eAstrophysicsGeneral Relativity and Quantum Cosmologytext