PDA

View Full Version : Let's call nothing a black dwarf



neilzero
2013-Oct-18, 03:25 PM
Instead of calling it a black dwarf, I suggest a white dwarf that will be cold in about 30 billion more years. The most numerous star in the Universe is the red dwarf star. These will run out of fuel in about 1000 billion years, then get cold. These black dwarf stars will only have about twice the density and diameter of cold brown dwarf stars = much bigger and much less density than a cold white dwarf. I suggest we call nothing a black dwarf to avoid confusion in the far future when there will be three or more much different bodies that could be called black dwarfs. There are likely none at present and I believe "black dwarf" has no official meaning among most astronomers. Let's keep it, no official meaning.
We already have to avoid calling main sequence stars slightly hotter than our Sun a white dwarf, so we jump from yellow dwarf to blue dwarf. Let's not repeat that error. Worse; some height impaired people may take offence at "Black Dwarf" Almost as bad as the planet Youranus and worse than Beetlejuice. Neil

Hornblower
2013-Oct-22, 03:42 PM
Yes indeed, it would be good to clean up the jargon for the sake of consistency. If I am not mistaken, we do not refer to the larger main sequence stars as giants, but rather limit the term to bloated stars that have evolved off the main sequence and are bloated as a result of changes related to the exhaustion of hydrogen fusion in their cores. Some of these bloated stars have as little as one solar mass, and perhaps less in the galactic core and old globular clusters. To be consistent in principle I would restrict dwarf to the collapsed remnants which we loosely call white dwarfs in their present state. This may or may not be the best choice, depending on our classification needs, but at least it would be consistent.

SkepticJ
2013-Oct-22, 11:25 PM
It's not terribly likely that recognizably English words will still be used tens of millions of years from now. Just look at Middle English to see how much things have changed in a paltry thousand years. Recognizably human people aren't that likely either, they'll be aliens in all but origin.

IsaacKuo
2013-Oct-23, 01:28 PM
I don't see a compelling reason to redefine what is a dwarf or a giant. In contrast, there's a compelling reason to keep them the same--for consistency with the existing body of scientific literature.

As for the definition of "black dwarf", the definition in Wikipedia will become the de facto definition within a few years, if it hasn't already. Simply put, there isn't any competing definition anyone is pushing, so the Wikipedia one will be the one which becomes the common knowledge standard.

Ken G
2013-Oct-25, 05:19 PM
I've heard of "closing the barn door after the horse has gotten out", but "closing the barn door 1000 billion years before the horse gets out" is a new one on me!