Dynamical determination of the quadrupole mass moment of a white dwarf
نویسنده
چکیده
In this letter we dynamically determine the quadrupole mass moment Q of the magnetic white dwarf WD 0137-349 by analyzing the period of the recently discovered brown dwarf moving around it in a close 2-hr orbit. It turns out that a purely Newtonian model for the orbit of WD 0137-349B, assumed circular and equatorial, is adequate, given the present-day accuracy in knowing the orbital parameters of such a binary system. Our result is Q = (−1.4615± 0.9004)× 10 kg m. It is the first dynamical, model-independent measurement of the quadrupole mass moment of a white dwarf.
منابع مشابه
Gravitational Radiation from Strongly Magnetized White Dwarfs
The magnetic fields of white dwarfs distort their shape generating an anisotropic moment of inertia. A magnetized white dwarf which rotates obliquely relative to the symmetry axis has a mass quadrupole moment which varies in time, so it will emit gravitational radiation. LISA may be able to detect the gravitational waves from two nearby, quickly rotating white dwarfs.
متن کاملDynamical determination of the quadrupole mass moment of the HD 209458 star
Aims. The aim of this paper is the dynamical determination of the quadrupole mass moment J2 of the main-sequence HD 209458 star. Methods. The adopted method is the confrontation between the measured orbital period of its transiting planet Osiris and a model of it. Osiris is assumed to move along an equatorial and circular orbit. Results. Our determination, for given values of the stellar mass M...
متن کاملFirst attempt to dynamically constrain the quadrupole mass moment of millisecond pul- sars
In this paper we attempt to dynamically constrain the quadrupole mass moment Q of the millisecond PSR B1257+12 pulsar from the orbital periods of its three planets, assumed to be in equatorial and circular orbits. Given the present-day accuracy in knowing their ephemerides, no post-Newtonian corrections to their motions are required. By conservatively assuming 1% and 10% uncertainties in the pu...
متن کاملAttempts to dynamically constrain the quadrupole mass moment of millisecond pulsars
In this paper we try to dynamically constrain the quadrupole mass moment Q of the millisecond PSR B1257+12 pulsar from the orbital periods of its three planets, assumed to be in equatorial and circular orbits. Given the present-day accuracy in knowing their ephemerides, no post-Newtonian corrections to their motions are required. By conservatively assuming 1% and 10% uncertainties in the pulsar...
متن کاملAttempts to dynamically constrain the quadrupole mass moment of the millisecond pulsar PSR J1909-3744
In this paper we try to dynamically constrain the quadrupole mass moment Q of the binary millisecond pulsar PSR J1909-3744, which has a white dwarf as companion, from deviations of the third Kepler law. By determining the pulsar’s mass mp from the general relativistic expression of the phenomenologically determined post-Keplerian parameter s, we get Q = (−0.1 ± 1.3) × 10 kg m which is compatibl...
متن کامل