Appearance, number, and history of highly compact binary systems in globular clusters

Journal Article · Sun Jul 15 04:00:00 EDT 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/162223· OSTI ID:6197524

Krolik, J H

I analyze the various evolutionary paths possible for highly compact binaries in globular clusters, where they come under the simultaneous influence of gravitational radiation and gravitational encounters with field stars. The observational appearance of those stages in which mass transfer occurs is discussed, with particular attention given to a new class of objects characterized by massive, nonequilibrium accretion disks created by catastrophic gravitational encounters. I then construct an analytic model to predict the number of highly compact binaries in each stage of evolution existing at present in the Galaxy's globular cluster system. Both steady transfer binaries, and systems in which a collaped stellar remnant acquires a massive, nonequilibrium accretion disk, are shown to be present in significant numbers. The number of steadily accreting degenerate dwarfs predicted (which can probably be identified with catacylsmic and Weak x-ray sources) is in good ageement with observations (approx.1000). There should also be approx.100 degenerate dwarfs surrounded by massive disks, whose observational properties are difficult to predict, but are probably quite luminous. Depending on circumstances, they may resemble catacylsmic variables, or possibly red giants. If highly compact binaries can lose angular momentum by no other mechanisms than those considered here, the number of medium strength (approx.10/sup 35/-10/sup 36/ ergs s/sup -1/) X-ray sources produced by steady transfer onto neutron stars (approx.10) is in conflict with the observations. If the strong (10/sup 36/-10/sup 38/ ergs s/sup -1/) X-ray sources can be identified with neutron star (or low-mass black hole)-plus-massive-disk systems, their predicted number (several) roughly agrees with the actual one.

• Research Organization: Harvard-Smithsonian Center for Astrophysics
• OSTI ID: 6197524
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 282:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DWARF STARS
DYNAMICS
ERUPTIVE VARIABLE STARS
GALAXIES
GRAVITATION
GRAVITATIONAL RADIATION
MASS
MATHEMATICAL MODELS
MATHEMATICS
MECHANICS
MILKY WAY
NEUTRON STARS
NOVAE
RADIATIONS
STAR ACCRETION
STAR CLUSTERS
STAR EVOLUTION
STARS
STATISTICS
VARIABLE STARS