Authors: Bruce Rout
The accurate measurement of extragalactic distances is a central challenge of modern astronomy, being required for any realistic description of the age, geometry and fate of the Universe. The measurement of relative extragalactic distances has become fairly routine, but estimates of absolute distances are rare.[1] In the vicinity of the Sun, direct geometric techniques for obtaining absolute distances, such as orbital parallax, are feasible, but heretofore such techniques have been difficult to apply to other galaxies. As a result, uncertainties in the expansion rate and age of the Universe are dominated by uncertainties in the absolute calibration of the extragalactic distance ladder[2]. Here we compare previous distance measurements to the galaxy NGC 4258 from both an estimate of Hubble's constant and a direct measurement of orbital motions in a disk of gas surrounding the nucleus of this galaxy to a direct measurement using a model of constant rotational velocity and galactic spiral morphology. The results of the comparison help validate methods of direct measurement of spiral galaxies to much greater distances.
Comments: 4 pages
Download: PDF
[v1] 5 Nov 2009
[v2] 6 Nov 2009
[v3] 9 Nov 2009
[v4] 18 Dec 2009
Unique-IP document downloads: 447 times
Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary. In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution. Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.
Add your own feedback and questions here:
You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful.