scholarly journals Testing the local spacetime dynamics by heliospheric radiocommunication methods

2008 ◽  
Vol 26 (4) ◽  
pp. 727-730
Author(s):  
H.-J. Fahr ◽  
M. Siewert
Keyword(s):  
Relativistic Effects ◽  
Careful Study ◽  
The Sun ◽  
Radio Tracking ◽  
Astronomical Observations ◽  
Distant Galaxies ◽  
Gravity Fields ◽  
General Relativistic ◽  
Pioneer 10 ◽  
Cosmological Spacetime

Abstract. According to general relativistic theories, cosmological spacetime is dynamic. This prediction is in excellent agreement with the huge majority of astronomical observations on large cosmic scales, especially the observations of cosmological redshifts of distant galaxies. However, on scales of heliospheric distances, verifications of general relativistic effects are based on Schwarzschild metric tests or kinetical corrections, such as the perihelion motion of Mercury, photon deflection at the Sun and gravitational photon redshifts in central gravity fields. As we will show in this paper, there is, however, a chance to detect new cosmologically relevant features on heliospheric scales by careful study of photon propagations in the local spacetime metrics, based on red- or blueshifts as a clear, but up to now overlooked, signature of the local spacetime dynamics. Thus, we propose the challenging possibility of carrying out experiments of cosmological relevance by simply using high-precision radio tracking of heliospheric spaceprobes, as already practised in cases like Pioneer-10/11, Galileo and Ulysses.

Another Potential Explanation for Pioneer Anomaly Cosmic Drag of an Orbit

2012 ◽  
Vol 433-440 ◽  
pp. 1587-1591
Author(s):  
Wei Jia Zhang
Keyword(s):  
Orbital Evolution ◽  
The Sun ◽  
Radio Tracking ◽  
Independent Research ◽  
Constant Acceleration ◽  
Potential Explanation ◽  
Pioneer Anomaly ◽  
Evolution Study ◽  
Pioneer 10

Analysis of the radio tracking data from the Pioneer 10/11 spacecraft at distances between about 20–70 AU from the Sun has consistently indicated the presence of a constant acceleration of 8.6× 10−8 cm/s−2 directed towards the Sun. This has been one of the most interesting and intriguing astrophysical problems in the last decade. Currently, an independent research rises from the planetary long-term orbital evolution study and may be helpful to understand the nature of Pioneer Anomaly. Furthermore, calculation shows that the Pioneer data match with the new discovery’s prediction very well.

scholarly journals Relativistic astrometry and astrometric relativity

2007 ◽  
Vol 3 (S248) ◽  
pp. 356-362
Author(s):  
S. A. Klioner
Keyword(s):  
Relativistic Effects ◽  
Building Blocks ◽  
High Accuracy ◽  
Relativity Theory ◽  
Newtonian Physics ◽  
Astronomical Observations ◽  
Time Space ◽  
Suitable Combination ◽  
General Relativistic ◽  
Standard Set

AbstractThe interplay between modern astrometry and gravitational physics is very important for the progress in both these fields. Below some threshold of accuracy, Newtonian physics fails to describe observational data and the Einstein's relativity theory must be used to model the data adequately. Many high-accuracy astronomical techniques have already passed this threshold. Moreover, modern astronomical observations cannot be adequately modeled if relativistic effects are considered as small corrections to Newtonian models. The whole way of thinking must be made compatible with relativity: this starts with the concepts of time, space and reference systems.An overview of the standard general-relativistic framework for modeling of high-accuracy astronomical observations is given. Using this framework one can construct a standard set of building blocks for relativistic models. A suitable combination of these building blocks can be used to formulate a model for any given type of astronomical observations. As an example the problem of four dimensional solar system ephemerides is exposed in more detail. The limits of the present relativistic formulation are also briefly summarized.On the other hand, high-accuracy astronomical observations play important role for gravitational physics itself, providing the latter with crucial observational tests. Perspectives for these astronomical tests for the next 15 years are summarized.

Additional Acceleration on Spacecrafts and Corresponding Theory for Aeronautic Manufacturing and Space Shuttle Design

2011 ◽  
Vol 199-200 ◽  
pp. 1122-1125 ◽  
Author(s):  
Wei Jia Zhang ◽  
Yang Lei
Keyword(s):  
Space Shuttle ◽  
Orbital Evolution ◽  
The Sun ◽  
Radio Tracking ◽  
Independent Research ◽  
Constant Acceleration ◽  
Mechanics Analysis ◽  
Evolution Study ◽  
Pioneer 10

Space probes now asks for a correction in aeronautic mechanics. Analysis of the radio tracking data from the Pioneer 10/11 spacecraft at distances between about 20–70 AU from the Sun has consistently indicated the presence of a constant acceleration of 8.6× 10−8 cm/s−2 directed towards the Sun. Currently, an independent research rises from the planetary long-term orbital evolution study and may be helpful to understand the nature of Pioneer Anomaly. Furthermore, calculation shows that the Pioneer data match with the new discovery’s prediction very well. Such nova theory will improve spacecraft and space shuttle design, and could enhance the accuracy, ensuring them into the designed orbit prompt.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

scholarly journals GERBERT OF AURILLAC: ASTRONOMY AND GEOMETRY IN TENTH CENTURY EUROPE

2013 ◽  
Vol 23 ◽  
pp. 467-471 ◽  
Author(s):  
COSTANTINO SIGISMONDI
Keyword(s):  
Rational Approximation ◽  
Equilateral Triangle ◽  
Tenth Century ◽  
The Sun ◽  
Astronomical Observations ◽  
The North ◽  
Celestial Pole ◽  
Gerbert Of Aurillac

Gerbert of Aurillac was the most prominent personality of the tenth century: astronomer, organ builder and music theoretician, mathematician, philosopher, and finally pope with the name of Silvester II (999–1003). Gerbert introduced firstly the arabic numbers in Europe, invented an abacus for speeding the calculations and found a rational approximation for the equilateral triangle area, in the letter to Adelbold here discussed. Gerbert described a semi-sphere to Constantine of Fleury with built-in sighting tubes, used for astronomical observations. The procedure to identify the star nearest to the North celestial pole is very accurate and still in use in the XII century, when Computatrix was the name of Polaris. For didactical purposes the Polaris would have been precise enough and much less time consuming, but here Gerbert was clearly aligning a precise equatorial mount for a fixed instrument for accurate daytime observations. Through the sighting tubes it was possible to detect equinoxes and solstices by observing the Sun in the corresponding days. The horalogium of Magdeburg was probably a big and fixed-mount nocturlabe, always pointing the star near the celestial pole.

scholarly journals XXI. On the dispersive power of the atmosphere, and its effect on astronomical observations

1815 ◽  
Vol 105 ◽  
pp. 375-383
Keyword(s):  
The Sun ◽  
Astronomical Observations ◽  
Dark Glass ◽  
Dispersive Power

Notwithstanding the pains which astronomers have taken to determine accurately the refraction of mixed light, nothing, I believe, has ever been done towards ascertaining the dispersive power of common air, or comparative degree of refrangibility of the differently coloured rays in their passage through our atmosphere. The importance of such an inquiry, however, must be obvious to every one who duly considers the effect which the different degrees of refrangibility of the variously coloured lights must necessarily produce in the apparent situations of differently coloured objects. Stars of different colours must be differently refracted, and the apparent altitude of the sun must vary according to the colour of the dark glass through which he is viewed.

scholarly journals Relative depolarization of the black hole photon ring in GRMHD models of Sgr A* and M87*

2021 ◽  
Vol 503 (3) ◽  
pp. 4563-4575
Author(s):  
A Jiménez-Rosales ◽  
J Dexter ◽  
S M Ressler ◽  
A Tchekhovskoy ◽  
M Bauböck ◽  
...  
Keyword(s):  
Black Hole ◽  
Relativistic Effects ◽  
Image Features ◽  
Black Hole Mass ◽  
Magnetic Turbulence ◽  
Intensity Images ◽  
General Relativistic ◽  
Sharp Image ◽  
Sgr A ◽  
Magnetohydrodynamic Simulations

ABSTRACT Using general relativistic magnetohydrodynamic simulations of accreting black holes, we show that a suitable subtraction of the linear polarization per pixel from total intensity images can enhance the photon ring feature. We find that the photon ring is typically a factor of ≃2 less polarized than the rest of the image. This is due to a combination of plasma and general relativistic effects, as well as magnetic turbulence. When there are no other persistently depolarized image features, adding the subtracted residuals over time results in a sharp image of the photon ring. We show that the method works well for sample, viable GRMHD models of Sgr A* and M87*, where measurements of the photon ring properties would provide new measurements of black hole mass and spin, and potentially allow for tests of the ‘no-hair’ theorem of general relativity.

Sign in / Sign up

Export Citation Format

Share Document