← Solar Motion Relative to the Metal-poor Halo ↑ →
In an
analysis of solar motion relative to halo stars, we found that the motion of the Sun with respect to halo stars within a cone with axis in the direction of Galactic rotation is significantly faster than its motion with respect to stars outside of that cone. This result can be explained by an
illusory component of radial velocity in accordance with the prediction of
relational quantum gravity. On account of the small population of halo stars this test does not demonstrate an illusory component of radial velocity at the 3σ level, or lead to a precise calculation of the orbital velocity of the Sun, but it does offer independent supporting evidence for the results of the regression test.
The Metal-poor Halo
The
metal-poor halo consists of very old stars in orbits inclined at disparate angles to the disc. For sufficiently low metal content, the metal-poor halo is essentially a non-rotating spheroid (
Gilmore, Wyse & Kuijken).
| To confirm this result, and to eliminate any residual rotation from disc stars, we used the catalogue of Beers. We selected 545 stars with metalicities [Fe ⁄ H] < −1.5. The population contains 207 dwarfs, 216 giants, and 122 RR Lyrae stars. We applied a variable cut on W-velocity (in the direction perpendicular to the disc): for n = 0, …, 10, |W + 7| > 10n.
We plotted mean V-velocity (in the direction of Galactic rotation) against the W-cut. If there is a net rotation in the halo, we should expect this to be more apparent for stars whose orbits have lower inclination to the disc. In practice the plots for V-velocity against cut on W level off above about 50 km s-1, at which point disc stars are eliminated. The plot confirms Gilmore et al.’s result, showing that rotation is effectively eliminated for W-velocities over 50 km s-1 and metalicities [Fe ⁄ H] < −1.5. Stars of different types in the halo would not be expected to have a different net rotation rate. In practice figure 4 shows poor agreement between the rate of rotation of RR Lyrae and the other populations, suggesting systematic measurement errors in the data. |
| We subdivided the populations using a cone with semi-angle 60° from the V-axis and calculated the mean velocity in the direction of Galactic rotation for the populations inside and outside the cone. There should be no systematic difference between the mean V-velocity for populations inside and outside the cone, but for each subpopulation the calculated velocity for stars inside the 60° cone is greater than that of stars outside the cone. Although the errors are of the order of 1 σ and individually are not significant, the repetition of the pattern across three populations shows a systematic error which is significant. |
Distance Adjustments
| A systematic difference between velocities inside and outside the cone could be caused by a systematic understatement of distance or a systematic overstatement of radial velocity. We applied systematic distance adjustments of 20% to dwarfs, 25% for giants, and 15% for RR Lyrae (figure 6), but this does not remove systematic differences between motion for stars inside and outside the cone. The resulting prediction of solar orbital velocity, 259 ± 9 km s-1, is in poor agreement an estimate of solar orbital velocity of 225 ± 5 km s-1 found from measurement of the proper motion of Sgr A* (Reid and Brunthaller, 2004), under the assumption that Sgr A* is stationary at the Galactic centre together with a combined distance estimate of 7.45 ± 0.17 kpc found from recent measurements. |
Distance and Velocity Adjustment
| We estimated from the mass models of Klypin, Zhao and Sommerville (2002) that, if the Galactic rotation curve is explained by a cosmological component of spectral shift, rather than by CDM or by MOND, then at the solar radius the cosmological component would contribute about 20-25% to spectral shift in the direction of orbital motion. We applied a cut of 23% to radial velocities. This affects velocities inside the cone more than those outside of it. After applying this factor to radial velocity a good fit was obtained by increasing distances increasing distances to dwarfs by 7%, increasing distances to giants by 10%, and decreasing distances to RR Lyrae by 5%. |
Solar Motion ↑ The Anatomy of Spiral Arms →
There are no comments on this page. [Add comment]