THE DISTANCE, MASS, AND RADIUS OF THE NEUTRON STAR IN 4U 1608-52

Journal Article · Thu Apr 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/712/2/964· OSTI ID:21394209

Guever, Tolga; Oezel, Feryal; Wroblewski, Patricia ^[1]; Cabrera-Lavers, Antonio ^[2]

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1. Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ (United States)
2. Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)

Low-mass X-ray binaries (LMXBs) that show thermonuclear bursts are ideal sources for constraining the equation of state of neutron star matter. The lack of independent distance measurements for most of these sources, however, prevent a systematic exploration of the masses and radii of the neutron stars, hence limiting the equation-of-state studies. We present here a measurement of the distance to the LMXB 4U 1608-52 that is based on the study of the interstellar extinction toward the source. We first model the individual absorption edges of the elements Ne and Mg in the high-resolution X-ray spectrum obtained with XMM-Newton. We then combine this information with a measurement of the run of reddening with distance using red clump stars and determine a minimum distance to the source of 3.9 kpc, with a most probable value of 5.8 kpc. Finally, we analyze time-resolved X-ray spectra of Type I X-ray bursts observed from this source to measure the mass and the radius of the neutron star. We find a mass of M = 1.74 +- 0.14 M{sub sun} and a radius of R = 9.3 +- 1.0 km, respectively. This mass and radius can be achieved by several multi-nucleon equations of state.

• OSTI ID: 21394209
• Journal Information: Astrophysical Journal, Vol. 712, Issue 2; Other Information: DOI: 10.1088/0004-637X/712/2/964; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION
EQUATIONS OF STATE
MASS
MATTER
NEUTRON STARS
NEUTRONS
TIME RESOLUTION
X RADIATION
X-RAY SPECTRA
BARYONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
HADRONS
IONIZING RADIATIONS
NUCLEONS
RADIATIONS
RESOLUTION
SORPTION
SPECTRA
STARS
TIMING PROPERTIES