Excerpts from mail.fanfic: 25-Mar-96 Re: [FanFic] Memories, chap.. by
Michael White@ccn.cs.dal 

On Sun, 24 Mar 1996, Damon Jason Casale wrote:
 

OK, so I'm commenting on the star, so sue me :)

This is two and a half years of time awake.  This *excludes*
hypersleep.  Notice how long the story pegs them as being asleep,
later on.  About 200.  Assume constant acceleration at one gee for the
first half of the trip, then constant deceleration at one gee.  The
velocity will always be changing.

OK, you said they have 2.5 years left to reach whatever star they're 
headed to. And they're 4/5 of the way there. So that means... crap, that 
wouldn't be 12.5 years, would it?

2.5 years they have, *awake*.  That's how long it'll seem like to them.
In other words, the total time each person will be on rotation, and awake,
will be 2.5 years.  4/5ths of the time it takes to get there is 200 years,
so 1/5th of it is 50 years.  So they'll only be awake for 2.5 out of 50
years of the last leg of the trip.  Now try again.  8)

Aw, hell, I'll say it is anyway ( I'm assuming you meant 4/5 in reference
to the time, not distance ).

Yes.

Constant acceleration at one gee? Sorry, but after 354 days at 9.8m/s
you start approaching c. And unless you have some funky doo-dad that lets
you go beyod c ( which would only cheapen the story, IMHO ) you will
simply stop accelerating at that point.

No you won't.  You're forgetting relativity, you doink.  At relativistic
speeds, .8 c + .8 c does not equal 1.6 c.  It equals about 0.98 c.

So that boils down to this. For the first year, you travel .5ly. Ditto for 
the last year as you decelerate. That places the distance of your star at 
11.5ly. Which is stretchable to encompass these stars:

e Indi at 11.2ly, Spectral class K5 V. Main sequence, like the sun, but 
class K :( Better than class M, but still dimmer=cooler than the Sun. 
It's orange. Not a likely canditate.

BD +43deg44 A/B at 11.2ly, spectral classes M4 and M5 respectively. If 
you're careful with your planet placement, I suppose it's OK. It's a 
binary star system, both red.

Luyten 789-6 at 11.2 ly, Spectral class M7e. It's a white dwarf. Which 
equals not a chance in hell there'd be anything of interest there :)

Procyon A/B at 11.4 ly, spectral classes F5 IV-V and a white dwarf, 
respectively. Binary star system, hotter than Sol. I doubt this one.

BD +59deg1915A/B at 11.5 ly, spectral classes M4 and M5 respectively. See 
BD +43deg44 A/B

CD -36deg1668 at 11.7 ly, spectral class M2 V. Red. Bright for red, but 
still... no.

G51-15 at 11.7ly, spectral class not classified. Super-dim. Super-cold. 
No chance. 'Nuff said :)

t Ceti at 11.9 ly, spectral class G8 V. A bit streched for distance, this 
is still the single best canditate for an Earth-like planet among the 
near stars. Yellow, like Sol, but a tad cooler. This is the only G-class 
star within 13ly except for a Centauri A, which is part of a trinary star 
system at 4.3ly. In short, PICK THIS ONE!

:)

Hope this helps.

Nope...

Damon Casale, scyth@andrew.cmu.edu

				* Love *
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