Re: Help with star catalogs requested

In message <Xns971D949FCBF63Klazmonllurdiaxorbgo@xxxxxxxxxxx>, Llanzlan Klazmon <Klazmon@xxxxxxxxxxxxxxxx> writes 
"ScottM" <scott@xxxxxxxxx> wrote in news:1133063494.173458.267760
@z14g2000cwz.googlegroups.com:

This might belong in alt.astronomy, but glancing in there, I hope not.

I'm looking for a set of information about visible stars that would be
useful in a work of fiction, and I'm finding it slow going. I can find
resources (like simbad) that can tell me that alpha Orionius is
Spectral type M2Iab. What I really want to know is what color it would
appear if you were on a hypothetical planet in the star's liquid-water
zone,


Not much different to the way the Sun appears on Earth - still far too
bright to look at with the naked eye.

Are you sure of that? I really don't want to sit down and work out how far away a habitable planet would be, but I wonder if the radiation per surface area is low enough for it to be tolerable. It's a fascinating system, with several companion stars which may even be entering the outer parts of the red giant.

The general cast of colours would be
a bit between normal daylight and what you see inside under a tungsten lamp
where the filament temperature is about 2,800 K, whereas the surface
temperature of alpha ori is around 3,100 K. So the view will have a
yellowish cast but your eyes tend to automatically compensate.

how long such a planet's year would be, if it's a multiple star
system and how the other system members would appear to the naked eye,


Forget habitable planets around massive stars like alpha ori (est 16 - 20
Msun). During the main sequence phase of such stars their radiation in the
UV is proportionately much higher than that of our Sun. This particular red
giant probably only started out on the main sequence as a blue giant about
six million years ago, not long enough for any terrestrial planets to have
even settled down. The red giant phase is also highly variable meaning that
your "habitable zone would not be stable for long.


Anyway, it's been done :-) Poul Anderson wrote a story ("Honorable Enemies") set on a planet of Betelgeuse, and added a bit explaining how it has habitable planets for the collection "Agent of the Terran Empire".
.

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