Talk:Tully-Fisher relation
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[edit] Completely Incorrect?
Tully-Fisher relation is not a method for measuring distances to spiral galaxies. The method is analyses of doppler shifting, and the Tully-Fisher relation is a relation between instrinsic brightness and the speed at which galaxies are rotating. Analyses of the doppler shifting allows determination of the radial velocity (speed at which it is rotating) and hence the Intrinsic brightness via the relation. This is then compared with the apparent magnitude to extrapolate a distance. This article needs completely re-wording in the immediate future. Jazzygm 16:38, 31 October 2006 (UTC)
- It is both; it is a relationship between the intrinsic luminosity of a galaxy and the rotation velocities of the stars in that galaxy. This is the fundamental T-F relation. But it can be used to determine distances, because intrinsic luminosity is related to apparent brightness by the square of the distance. I agree with the "badly written / confusing" tag on the page, however; this page needs help. -- David W. Hogg 00:57, 4 January 2007 (UTC)
- Okay, I blew ten minutes and re-wrote the article. I hope people add details. -- David W. Hogg 01:16, 4 January 2007 (UTC)
[edit] Open source compatibility note POV?
Tully-Fisher relation links as a reference to a PowerPoint file whence I found a specific fact (the T ∝ V^4 formula) that I didn't find in my other two sources. Because PPT is proprietary and Wikipedia is open-source / intended to be free and Free to all / has a significant non-Windows readership, I mentioned that the file works in OpenOffice.org. Is this statement POV, or fair notice for those without PowerPoint? --Geoffrey 02:16, 21 Apr 2004 (UTC)
- Looks fine to me: IM(NS)HO it's more neutral to mention alternative methods of opening a file. Indeed mentioning the file format at all is an improvement on the usual situation where you click on a link, expecting HTML to pop up quickly, and your browser appears to sulk for ages while it opens some huge file: I'm all in favour of stating the format of an external link whenever it's anything other than HTML (or near equivalent e.g. PHP). --Phil | Talk 06:45, Apr 21, 2004 (UTC)
- Pedantic note: as far as the browser is concerned, PHP is HTML - or, rather, normally is. It's just that it's generated by the server when you ask for it, not stored as a complete file somewhere. And in fact, a PHP file could (I believe) actually generate an image, or even a PowerPoint presentation, theoretically - making it even more important to label the link, as its target may well end .php. - IMSoP 14:31, 21 Apr 2004 (UTC)
- Just mention its type, not how to open it, the reader is not daft. Open Source POV is pushed in some articles around here, and that is tacitly accepted, but it shouldn't be. Pete/Pcb21 (talk) 19:24, 21 Apr 2004 (UTC)
- Agreed, just metion the type. Its also openable in staroffice, microsoft office and with microsofts powerpoint viewer. Not listing these other opitions implies a bias towards openoffice. So best to just say that its a powerpoint presentation. I've also added in their original paper as a reference. --Albert White 13:39, 10 April 2006 (UTC)
