Winds from neutron stars and strong type I X-ray bursts

Abstract

view Abstract Citations (34) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Winds from Neutron Stars and Strong Type I X-Ray Bursts Nobili, Luciano ; Turolla, Roberto ; Lapidus, Iosif Abstract A model for stationary, radiatively driven winds from X--ray bursting neutron stars is presented. General relativistic hydrodynamical and radiative transfer equations are integrated from the neutron star surface outwards, taking into account for helium nuclear burning in the inner, dense, nearly hydrostatic shells. Radiative processes include both bremsstrahlung emission--absorption and Compton scattering; only the frequency--integrated transport is considered here. It is shown that each solution is characterized by just one parameter: the mass loss rate $\Mdot$, or, equivalently, the envelope mass $\Menv$. We found that, owing to the effects of Comptonization, steady, supersonic winds can exist only for $\Mdot$ larger than a limiting value $\Mdot_{min} \approx\Mdot_{E}$. Several models, covering about two decades in mass loss rate, have been computed for given neutron star parameters. We discuss how the sequence of our solutions with decreasing $\Menv$ can be used to follow the time evolution of a strong X--ray burst during the expansion/contraction phase near to the luminosity maximum. The comparison between our numerical results and the observational data of Haberl {\it et al.\/} (1987) for the bursts in 4U/MXB 1820-30 gives an estimate for both the spectral hardening factor and the accretion rate in this source. Publication: The Astrophysical Journal Pub Date: September 1994 DOI: 10.1086/174643 arXiv: arXiv:astro-ph/9405065 Bibcode: 1994ApJ...433..276N Keywords: Hydrodynamics; Neutron Stars; Radiative Transfer; Stellar Mass; Stellar Models; Stellar Radiation; Stellar Winds; X Rays; Bremsstrahlung; Bursts; Compton Effect; Mathematical Models; Stellar Mass Accretion; Astrophysics; HYDRODYNAMICS; RADIATION MECHANISMS: NONTHERMAL; RADIATIVE TRANSFER; STARS: INDIVIDUAL ALPHANUMERIC: 4U/MXB 1820-30; STARS: MASS LOSS; STARS: NEUTRON; X-RAYS: BURSTS; Astrophysics E-Print: 32 pages (10 postsript figures available on request), PlainTeX full text sources arXiv | ADS | data products SIMBAD (4)