2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/218836We consider an ensemble of closed strings in a compact space with stable one cycles and compute the speed of sound resulting from string thermodynamics. Possible applications to the issue of Jeans instability in string gas cosmology are mentioned.6 pages, 1 figure, one reference added, figure re-sized one reference added, one footnote added, a typo correctedHigh Energy Physics - TheoryAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Phenomenologytext