2003/10/09 by D. G. Yakovlev, К. П. Левенфиш, K. P. Levenfish +4
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #High-pressure geophysics and materials #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1051/0004-6361:20034191
published as Astron.Astrophys. 417 (2004) 169-179 · 12 pages, 5 figures, 4 tables, LaTeX2e with aa.cls v.5.3 (included). Accepted by A&A
arxiv created 2003/10/09 · openalex publication_date 2004/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We calculate the thermal structure and quiescent thermal luminosity of accreting neutron stars (warmed by deep crustal heating in accreted matter) in soft X-ray transients (SXTs). We consider neutron stars with nucleon and hyperon cores and with accreted envelopes. It is assumed that an envelope has an outer helium layer (of variable depth) and deeper layers of heavier elements, either with iron or with much heavier nuclei (of atomic weight ) on the top [CITE]. The relation between the internal and surface stellar temperatures is obtained and fitted by simple expressions. The quiescent luminosity of the hottest (low-mass) and coldest (high-mass) neutron stars is calculated, together with the ranges of its possible variations due to variable thickness of the helium layer. The results are compared with observations of SXTs, particularly, containing the coldest (SAX J1808.4-3658) and the hottest (Aql X-1) neutron stars. The observations of SAX J1808.4-3658 in a quiescent state on March 24, 2001 [CITE] can be explained only if this SXT contains a massive neutron star with a nucleon/hyperon core; a hyperon core with a not too low fraction of electrons is preferable. Future observations may discriminate between the various models of hyperon/nucleon dense matter. The thermal emission of SAX J1808.4-3658 is also sensitive to the models of plasma ionization in the outermost surface layers and can serve for testing such models.