The Action Barrier: Redefining Stellar Ignition Beyond Mass Thresholds

The conventional stellar ignition threshold of approximately 80 MJ fails to explain observed cases where lower-mass objects achieve stable hydrogen fusion while higher-mass objects do not. This study introduces the Action Barrier—a density-spin dependent threshold that supersedes mass as the primary determinant of stellar ignition. We present the foundational equations governing ignition energy, define the Action metric A= M (D·S), and demonstrate through observational data that objects cross into fusion states based on Action rather than mass alone. Analysis of mass-paradox systems confirms that a 63 MJ compact object achieves ignition while an 84 MJ diffuse object fails, validating the Action Barrier framework.