32,146 research outputs found

    Is there a propeller neutron star in γ\gamma Cas?

    Full text link
    γ\gamma Cas is the prototype of a small population of B0-B1.5 III-V classical Be (cBe) stars that emit anomalous and hard X-rays with a unique array of properties. γ\gamma Cas is known to host, like other cBe stars, a decretion disk and also a low mass companion. Recently Postnov et al. have posited that this companion is a magnetized rapidly spinning neutron star that deflects direct gravitational accretion from a stellar/disk wind via the "propeller mechanism." These authors state that the key X-ray observations are "remarkably well produced" in this scenario. We reexamine this mechanism in detail and conclude that there are a number of fatal objections in its application to the γ\gamma Cas case. Among other considerations these issues include the prediction under the propeller scenario of a much smaller population of γ\gamma Cas stars than is observed and the lack of allowance for observed correlations of X-ray and UV and/or optical properties over a variety of timescales.Comment: 9 page
    corecore