Sources of celestial x-ray bursts

Journal Article · Fri May 01 04:00:00 EDT 1981 · Sci. Am.; (United States)

DOI:https://doi.org/10.1038/scientificamerican0581-72· OSTI ID:5756777

Lewin, W H.G.

It was noted that a short burst of x-rays is being emitted by sources near the center of our galaxy and in globular clusters of stars. They repeat at irregular intervals from a few hours to a few days. The evolution of thought and evidence to support it concerning the source and nature of the bursts is followed in this paper. The accepted explanation of these bursts is as follows: (1) x-ray sources are of 2 classes: (i) Class 1 objects are neutron stars in a binary system. The companion star is believed to be 10 to 20 times more massive than the sun. X-ray pulsation and eclipsing of the neutron star by the companion are characteristic of this group. No x-ray bursts are found among this group. (ii) Class 2 objects are also neutron stars in a binary system, but their companion stars are much less massive than Class 1. There is no evidence of pulsation or eclipsing. The companions are not visible, the explanation being that the small companion lies in the shadow of the accretion disk. These sources are associated with x-ray bursts. The main difference in Class 1 objects and Class 2 objects is the mass of the companion stars. It is believed that Class 1 objects are young neutron stars with a strong magnetic field responsible for the concentration of infalling matter at the magnetic poles which tends to make nuclear fuel barn steadily, i.e., no bursts. Class 2 objects are old neutron stars whose magnetic fields have either decayed or the magnetic dipole axis has become aligned with axis of rate rotation. (2) The x-ray bursts are the results of a gigantic thermonuclear flash on the neutron star. (SC)

• Research Organization: Massachusetts Inst. of Tech., Cambridge
• OSTI ID: 5756777
• Journal Information: Sci. Am.; (United States), Journal Name: Sci. Am.; (United States) Vol. 24:5; ISSN SCAMA
• Country of Publication: United States
• Language: English

Related Subjects

640102 -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DISTANCE
EMISSION SPECTRA
GALAXIES
GRAVITATIONAL FIELDS
MAGNETIC FIELDS
MASS
MILKY WAY
NEUTRON STARS
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
SIZE
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
THERMONUCLEAR REACTIONS
VISIBLE SPECTRA
X-RAY SPECTRA