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The Hypergiant

The hypergiant is a yellow hypergiant (YHG) which is currently cooling down and becoming a red hypergiant. It is roughly something that has a spectral type of maybe G3 0-Ia, though the exact spectral type doesn't matter. I chose a yellow hypergiant because they are rare and slightly unstable and undergo changes in their apparent magnitudes.

The Star System

The star system consists of a K2V star and I would like the star system not to be disrupted. Its outer influence is probably something like ≈50,000AU but this is a rough estimate.

Some Numbers

  • Mass - 0.82 M☉
  • Luminosity - 0.452 L☉
  • Radius - 0.853 R☉
  • Habitable Planet Distance from star - 0.66 AU
  • End of My Star's Oort Cloud - ≈50,000 AU but this is a very rough estimate

The Question

Is it possible for the hypergiant to be extremely bright while not affecting the star system (so it can be important for the people in the habitable planet's mythology) and where approximately would the hypergiant have to be?

Note: I can give you more info. Just ask.

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  • $\begingroup$ What makes you think that distance is at all relevant to mythology? $\endgroup$
    – sphennings
    Oct 1 at 0:00
  • $\begingroup$ @sphennings The farther away a star is, the less visible it is and the more bright a star or any other celestial object is, it is probably going to be perceived as more important. $\endgroup$
    – Neil Iyer
    Oct 1 at 0:22

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Is it possible for the hypergiant to be extremely bright while not affecting the star system (so it can be important for the people in the habitable planet's mythology)

Yes. Every bright star in our night sky is part of many mythologies. And unlike what the astrologist I see every other weekend says, those stars cannot affect us here on Earth in any way. [Bleep] you Gemini and your retrograde Mercury!

As for myths, take Antares for example. It is the most important star for the Māori people, the national star for the Chinese Shang dinasty, and every other mesopotamian civilization related it to at least one important deity.

But Antares is red, you want a yellow one. So let's see...

and where approximately would the hypergiant have to be?

Well, Rho Cassiopeiae is a known yellow hypergiant. It just isn't that bright, nor in anywhere important in the sky.

Just make it really close, like Alpha Centauri close, and it would appear much, much brighter. As to the where, make it a polar star, or make it appear in the sky together with a season so that it becomes "she (or he) who bringeth summer!".

Or maybe put it into a latitude so that it goes below the horizon when you reach a border (either northern or southern) of a kingdom. The star would be the heavenly guardian of the realm.

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  • $\begingroup$ That is really interesting. As for the yellow hypergiant part, I'm sure it'll be much brighter than usual even at a distance where it does nothing to my K2V star system. $\endgroup$
    – Neil Iyer
    Sep 30 at 22:42
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    $\begingroup$ If you place Rho Cassiopeiae-like star at 4LY away from your system, its magnitude would be about -14, making it be visible on the daylit sky like a moon or something. In fact our moon has -12 apparent magnitude, so this star would be 8x brighter. Quite a sign for tribes to make that star mythical, huh? $\endgroup$
    – Vesper
    Oct 1 at 12:46
  • $\begingroup$ @Vesper I... hadn't thought about that. That blew my mind. Now I'm thinking, other yellow hypergiants might have come that close to Earth in the distant past (say, the cretaceous or even cambrian eras) and we wouldn't know, but any creatures back then would have quite the sight. $\endgroup$
    – The Square-Cube Law
    Oct 1 at 13:41

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