Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-10-10
Astrophys.J.548:919-931,2001
Astronomy and Astrophysics
Astrophysics
10 pages with 10 gif figures, emulateapj5.sty. Accepted for publication in The Astrophysical Journal
Scientific paper
10.1086/319016
We study the dynamical stability against bar-mode deformation of rapidly and differentially rotating stars in the first post-Newtonian approximation of general relativity. We vary the compaction of the star $M/R$ (where $M$ is the gravitational mass and $R$ the equatorial circumferential radius) between 0.01 and 0.05 to isolate the influence of relativistic gravitation on the instability. For compactions in this moderate range, the critical value of $\beta \equiv T/W$ for the onset of the dynamical instability (where $T$ is the rotational kinetic energy and $W$ the gravitational binding energy) slightly decreases from $\sim 0.26$ to $\sim 0.25$ with increasing compaction for our choice of the differential rotational law. Combined with our earlier findings based on simulations in full general relativity for stars with higher compaction, we conclude that relativistic gravitation {\em enhances} the dynamical bar-mode instability, i.e. the onset of instability sets in for smaller values of $\beta$ in relativistic gravity than in Newtonian gravity. We also find that once a triaxial structure forms after the bar-mode perturbation saturates in dynamically unstable stars, the triaxial shape is maintained, at least for several rotational periods. To check the reliability of our numerical integrations, we verify that the general relativistic Kelvin-Helmholtz circulation is well-conserved, in addition to rest-mass energy, total mass-energy, linear and angular momentum. Conservation of circulation indicates that our code is not seriously affected by numerical viscosity. We determine the amplitude and frequency of the quasi-periodic gravitational waves emitted during the bar formation process using the quadrupole formula.
Baumgarte Thomas W.
Saijo Motoyuki
Shapiro Stuart L.
Shibata Masaru
No associations
LandOfFree
Dynamical Bar Instability in Rotating Stars: Effect of General Relativity does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dynamical Bar Instability in Rotating Stars: Effect of General Relativity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dynamical Bar Instability in Rotating Stars: Effect of General Relativity will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-406552