THE MASS AND RADIUS OF THE NEUTRON STAR IN 4U 1820-30

Guver T., Wroblewski P., Camarota L., Ozel F.

ASTROPHYSICAL JOURNAL, vol.719, no.2, pp.1807-1812, 2010 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 719 Issue: 2
  • Publication Date: 2010
  • Doi Number: 10.1088/0004-637x/719/2/1807
  • Journal Name: ASTROPHYSICAL JOURNAL
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1807-1812
  • Keywords: stars: neutron, stars: individual (4U 1820-30), X-rays: binaries, X-RAY-BURSTS, QUASI-PERIODIC OSCILLATIONS, GLOBULAR-CLUSTERS, INTERSTELLAR-MEDIUM, NGC 6624, COMPTONIZED SPECTRA, MODEL ATMOSPHERES, SPECTROSCOPY, 4U-1820-30, ABSORPTION
  • Istanbul University Affiliated: No

Abstract

We report on the measurement of the mass and radius of the neutron star in the low-mass X-ray binary 4U 1820-30. The analysis of the spectroscopic data on multiple thermonuclear bursts yields well-constrained values for the apparent emitting area and the Eddington flux, both of which depend in a distinct way on the mass and radius of the neutron star. The distance to the source is that of the globular cluster NGC 6624, where the source resides. Combining these measurements, we uniquely determine the probability density over the stellar mass and radius. We find the mass to be M = 1.58 ± 0.06 M sun and the radius to be R = 9.1 ± 0.4 km.

We report on the measurement of the mass and radius of the neutron star in the low-mass X-ray binary 4U 1820-30. The analysis of the spectroscopic data on multiple thermonuclear bursts yields well-constrained values for the apparent emitting area and the Eddington flux, both of which depend in a distinct way on the mass and radius of the neutron star. The distance to the source is that of the globular cluster NGC 6624, where the source resides. Combining these measurements, we uniquely determine the probability density over the stellar mass and radius. We find the mass to be M = 1.58 +/- 0.06 M(circle dot) and the radius to be R = 9.1 +/- 0.4 km.