Re: Return to No Stealth in Space
- From: jdnicoll@xxxxxxxxx (James Nicoll)
- Date: Tue, 18 Mar 2008 18:58:45 +0000 (UTC)
In article <c5edc0c1-efe7-47ca-9abd-4008643381b9@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
<sigidunum@xxxxxxxxx> wrote:
On Mar 18, 7:01 pm, jdnic...@xxxxxxxxx (James Nicoll) wrote:
might have a peak power output of 5^16 Watts (plus whatever
for ineffeciencies).
Could we spot this at 4.3 LY? Would we recognize it
for what it was?
Cheap dumb answer: the power output of the Sun is 4 x 10^26 watts.
So, this is about 10^-10 as bright as the Sun.
One way to phrase the question: can we detect a one-ten billionth
change in luminosity?
As for absolute magnitude, Alpha Centauri is about as bright as the
Sun (it's a bit brighter actually, but this is BOTE). Its visual
magnitude is just about 0.0. So, your Centuarian torchship would have
an absolute magnitude of about +25.
I'm thinking no, we wouldn't see it.
OK, this probably has a flaw in it somewhere: The shuttle
jet is what, 3000K? And ISP scales as the square root of temperature,
so if the ISP in this case is 500,000 or about 1000 times greater
than the shuttle's ISP, then the temperature should be somewhere
around 3 billion degrees.
If I run that through Wein's law, I get a peak at about
10^-12 m. That's gamma radiation, right?
--
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