Dependence Of Mass Loss Research Articles

Single-Lined Spectroscic Appearances During the Evolution of a Massive Binary System

We calculated the evolution of both components of a massive binary system with masses 26 MO and 23.4 MO, initial period 27.4 days, through a case B of mass transfer, up to the end of the core helium burning phase of the primary (and further to the end of the main sequence of the secondary). For the WC phase we adopted Langer's (1989) mass dependent mass loss rate Ṁ ~ M2.5). The luminosities were transformed to visual magnitudes, applying bolometric corrections for O stars of Code et al. (1976) and Flower (1977) and BC = − 4.5 for the WR star (Smith and Maeder, 1989). If conservative mass transfer is adopted, the WR star is about 1.2 to 2.0 magnitude less brighter in the visual than the O star during the WN phase (lasting 1.5 105 yr). The brightness difference reaches almost 3 magnitudes during the WC + 08 phase (lasting 4.3 105 yr), showing the system as a single-lined O-type (!) spectroscopic binary. During the WR phase the mass function of this system varies from 0.67 sin3i to 0.05 sin3i! Nonconservative mass transfer and (or) a smaller initial mass ratio may result in the inverse situation, a single-lined WR binary with a large mass function (De Greve et al., 1988). Some of the results are shown in table 1 below.

The dependence of mass loss on the basic stellar parameters

We determined the dependence of mass loss on the stellar parameters for O and B stars of various luminosities. We used four homogenous sets of mass loss rates derived by different authors from the radioflux, the infrared excess, the UV lines and Hα emission. As the rates derived from the radio flux are the least dependent on model assumptions for the stellar wind, these will be adopted as our standards. The others sets of mass loss rates will be corrected for the differences in the adopted wind model, especially in the velocity law, by scaling the rates to those derived from radio data, using the stars which the different sets have in common.

The effect of approach direction on damage in MgO due to spherical particle impact

The damage produced by spherical particle impact against {1 0 0} surfaces of MgO has been investigated over a range of impact angles for a fixed particle velocity and over a range of particle velocities for a fixed impact angle. The mass of material removed by each impact was determined gravimetrically, and the crater and surrounding damage were studied by means of surface profilometry and scanning electron microscopy. A numerical computer model of the crater formation process was developed which was able to predict crater geometries in close agreement with those observed experimentally. This same model also provided estimates of the dynamic hardness, the contact time and the energy transmitted to the surface during the impact. The mean dynamic hardness was ~ 25% less than that measured in previous normal impact studies [1] on MgO of similar static hardness. The contact time and energy calculations give some insight into the reasons why the energy balance model, which successfully describes the velocity dependence of mass loss under normal impact conditions, breaks down for oblique impact.