2003/03/03 by Jeremy Heyl, Jeremy S. Heyl, Heyl, Jeremy S.
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Mechanics and Biomechanics Studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0303003
7 pages
arxiv created 2003/03/03 · openalex publication_date 2003/03/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
General relativity limits the compactness of static stars. If the pressure of the fluid is positive and the density decreases with distance from the center, the value of the circumferential radius of the star must be greater than (9/4) G M/c2, or equivalently the redshift of the surface must be less than two. If constraints on the equation of state of the material are relaxed, general relativity alone does not restrict the redshift of a static stellar surface. However, because black hole candidates in the universe generally accrete material from their environs, the process of accretion provides upper limits on the redshift of a astrophysical black-hole candidates.