Astroboffins out FREAK 'BI' GALAXY A team of astrophysicists have discovered the first celestial agglomeration that qualifies as both an old, settled-down ellipical galaxy and a young, vigorous spiral galaxy. Centarus A, more prosaically known as NGC 5128 and discovered in 1826, has long been recognized as an elliptical galaxy, but a paper in The Astrophysical …
"about 12,000,000 light years, or about 1.14×10^20 kilometers (7.05×10^13 miles)"
How do you drop 6 orders of magnitude when converting from km to miles? (I think that should be "7.05×10^19 miles".)
Shouldn't this be in meters only, anyway, as a result of the recent vote to use only SI units (1.14×10^23 m)? Or does it fall under the altitude exception, which means it should be 3.72×10^23 feet?
Indeed - if El.Reg were paying attention to their own poll results, this wouldn't have happened. Having said that, when talking about galactic diameters and intergalactic distances then even km isn't really appropriate any more - lightyears or parsecs are how the astronomers would measure it (and according to Wikipedia, parsecs is preferred).
The parsec is at least a "non-S.I. unit accepted for use with S.I." just as hours and minutes are. So it would seem that use of parsecs in El.Reg stories would at least generally comply with the outcome of the "units of measurement" poll.
Question: Considering that it is generally held that a ring galaxy is formed by one galaxy passing directly though the centre of another, how do they know that how do they know that this is not just an intermediate stage in the formation of a ring* galaxy involving a spiral and an elliptical, where the galaxy sizes are similar and where we are seeing at 'just the right moment' for it to look like an elliptical with arms?
I can't access the paper and am not paying a fiver to read it, but does it make any mention of any HII regions and how does the paper negotiate it being not just a stage in the development of a ring galaxy - or does it make no mention of such a possibility?
* OK, so usually it would be assumed that a smaller compact galaxy would pass through a larger galaxy and, two galaxy's of similar size may not develop into a well defined ring (if at all), but it illustrates the nature of the question I hope.
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