NEWS: On the Annihilation of Stars that Might Have Been

bean said:

Sort of.

AU = c * tauA = 1.49597870691 x 1011 (± 3) m
light time for 1 AU (tauA) = 499.004783806 (± 0.00000001) s
c = speed of light

KUNGFOO said:
This is interesting, but I still prefer Death Stars as a primary means of destroying planets.

Chainlink said:

Ok, I am finding that the AU is a astronomical unit of measurement that has been in use since the 1600's. Our capability to accurately measure the distance between here and the sun has improved greatly and the unit of measurement has changed with the times.
But that said, it seems about as arbitrary as a foot or a yard, an inch, a meter, whatever.
It is a specific and fixed unit of measurement.
Meaning an AU is not any longer or shorter in another galaxy.

Perhaps I didn't phrase that well or chose a poor example. My point was that , lets us say even between Yellow Dwarf stars there is such an enormous amount of variation ( and also I'm thinking of variations within gas giant planets) that 1.5 AH couldn't be the "the significant point of no return" for all gas giant/ yellow dwarf systems. (could it ? )
If the star was a little hotter wouldn't it be 1.8 ? Or if the Planet had more protective H3 in the atmosphere could it be 1.2 ? My confusion and the point of my original question was are they saying 1.5 is the PNR for Jupiter or for HD209458b or are they really postulating that 1.5 AU is the threshold for Gas Giant / Star proximity no matter what the other variables are ? ( that is what seemed absurd to me)

radiofrank said:

You're quite right, of course. "Arbitrary" might not have been the right word to use, but I meant it in the sense that the Earth-Sun distance was used as the definition for an AU.

radiofrank, said :
AU is an arbitrary measurement; in this case, it is the distance between the Earth and the Sun.

Chainlink said:

Is there some other case where the AU is NOT the distance between the earth and the sun ?
I mean besides the case of if an alien life were making up their own measurements from their home planets to their star.

radiofrank said:

No, it's specifically meant as the distance between the earth and the sun.

I seem to have chosen my words poorly, and I should really proofread my posts before submitting them. Ha.

"If you take a planet even slightly beyond this, molecular hydrogen becomes unstable and no more H3+ is produced. The self-regulating, 'thermostatic' effect then disintegrates and the atmosphere begins to heat up uncontrollably."

_DictionaryGirl_ will so call the X-Men on you, so seriously, don't even think about it.