Measurement of the Masses of the Neutron Star,Her X-1,and Its Binary Companion,Hz Her,as Derived from the Study of 1.24-Second Optical Pulsations from the Hz Her -Her X-1Binary System and the X Ray-to-Optical Reprocessing Reflection and Transmission Mechanisms.

摘要

Intermittent optical pulsations at the 0.1--0.3percent level have been detected from this binary system in over 500hours of optical observations. These pulsations are present only for well defined values of the 1.7-day (binary) and 35-day phases. Positions of the pulsation-emitting regions,projected onto the orbital plane,have been measured and three distinct regions have been resolved. A simple model is put forth which accounts for the observed binary behavior,which gives a direct determination of the mass ratio, M/sub HZ Her//M/sub Her X-1/ = 1.69 +- 0.05,and which establishes that the spin of the pulsar is prograde. Additionally it is shown that HZ Her fills its critical Roche lobe. Using the above,the known x ray eclipse duration,and the mass function,the orbital inclination is calculated to be i = 85exp 0 +- 5exp 0and the masses to be M/sub Her X-1/ = 1.28 +- 0.08 M/sub solar/and M/sub HZ Her/ = 2.16 +- 0.07 M/sub solar/. Constraints on the physical parameters of the accretion stream and disk are derived from the data. The nature of the 35-day modulation of the data is discussed in relation to various models. (ERA citation 02:008131)