* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Physics News -> Lense-Thirring effect
Post Info TOPIC: Lense-Thirring effect
Esnuka


New

Posts: 1
Date:
RE: Lense-Thirring effect
Permalink  
 

Blobrana wrote:

NASA Announces Results of Epic Space-Time Experiment

Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.
Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B).
Read more 

I believe there is no frame-dragging effect of gravity on mass, only on electromagnetic energy!

Curiously, the Lense-Thirring effect in Gravity Probe B has the same value than the geodetic effect of the Earth around the Sun.

NASA error?

An interesting experiment!

Understanding Gravity Probe-B experiment without math 

http://www.molwick.com/en/gravitation/082-gravity-probe-b.html 

Gravity Probe B effects



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: A possible signature of Lense-Thirring precession in dipping and eclipsing neutron-star low-mass X-ray binaries
Authors: Jeroen Homan

Relativistic Lense-Thirring precession of a tilted inner accretion disk around a compact object has been proposed as a mechanism for low-frequency (~0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray binaries. A substantial misalignment angle (~15-20 degrees) between the inner-disk rotation axis and the compact-object spin axis is required for the effects of this precession to produce observable modulations in the X-ray light curve. A consequence of this misalignment is that in high-inclination X-ray binaries the precessing inner disk will quasi-periodically intercept our line of sight to the compact object. In the case of neutron-star systems this should have a significant observational effect, since a large fraction of the accretion energy is released on or near the neutron-star surface. In this Letter I suggest that this specific effect of Lense-Thirring precession may already have been observed as ~1 Hz QPOs in several dipping/eclipsing neutron-star X-ray binaries.

Read more (69kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Kerr metric
Permalink  
 

Title: A Metric for Testing the Nature of Black Holes
Authors: Tim Johannsen (Waterloo, Perimeter, Arizona)

In general relativity, astrophysical black holes are uniquely described by the Kerr metric. Observational tests of the Kerr nature of these compact objects and, hence, of general relativity, require a metric that encompasses a broader class of black holes as possible alternatives to the usual Kerr black holes. Several such Kerr-like metrics have been constructed to date, which depend on a set of free parameters and which reduce smoothly to the Kerr metric if all deviations vanish. Many of these metrics, however, are valid only for small values of the spin or small perturbations of the Kerr metric or contain regions of space where they are unphysical hampering their ability to properly model the accretions flows of black holes. In this paper, I describe a Kerr-like black hole metric that is regular everywhere outside of the event horizon for black holes with arbitrary spins even for large deviations from the Kerr metric. This metric, therefore, provides an ideal framework for tests of the nature of black holes with observations of the emission from their accretion flows, and I give several examples of such tests across the electromagnetic spectrum with current and near-future instruments.

Read more (33kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
RE: Lense-Thirring effect
Permalink  
 

Title: Lense-Thirring precession in strong gravitational fields
Authors: Chandrachur Chakraborty, Parthasarathi Majumdar

An exact expression for the rate of dragging of inertial frames (Lense-Thirring (LT) precession) in a general stationary spacetime, is derived without invoking the weak field approximation. This expression, when used for the Kerr metric, leads to the LT precession frequency in the strong gravity regime appropriate to compact gravitating objects like rotating neutron stars and black holes. Numerical values of the precession rate are computed for a few known cases of pulsars (including a double-pulsar) and compared to the precession rates in the weaker gravity regimes of the earth and the sun.

Read more (102kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Troubled probe upholds Einstein

An epic victory over daunting challenges, or a costly project that should never have flown? After nearly half a century of work and US$750 million spent, Gravity Probe B, one of NASA's longest-running mission programmes, has finally achieved some scientific closure. But it has yet to quiet its critics.
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
Frame-dragging
Permalink  
 

NASA Announces Results of Epic Space-Time Experiment

Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.
Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B).
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
Lense-Thirring effect
Permalink  
 

Title: Advances in the measurement of the Lense-Thirring effect with planetary motions in the field of the Sun
Authors: Lorenzo Iorio
(Version v3)

E.V. Pitjeva, by processing more than 400,000 planetary observations of various types with the dynamical models of the EPM2006 ephemerides, recently estimated a correction to the canonical Newtonian-Einsteinian Venus' perihelion precession of -0.0004 ± 0.0001 arcseconds per century. The prediction of general relativity for the Lense-Thirring precession of the perihelion of Venus is -0.0003 arcseconds per century. It turns out that neither other mismodelld/unmodelled standard Newtonian/Einsteinian effects nor exotic ones, postulated to, e.g., explain the Pioneer anomaly, may have caused the determined extra-precession of the Venus orbit which, thus, can be reasonably attributed to the gravitomagnetic field of the Sun, not modelled in the routines of the EPM2006 ephemerides. However, it must be noted that the quoted error is the formal, statistical one; the realistic uncertainty might be larger. Future improvements of the inner planets' ephemerides, with the inclusion of the Messenger and Venus-Express tracking data, should further improve the accuracy and the consistency of such a test of general relativity which would also benefit of the independent estimation of the extra-precessions of the perihelia (and the nodes) by other teams of astronomers.

Read more (10kb, PDF)

__________________
Page 1 of 1  sorted by
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Physics News -> Lense-Thirring effect


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard