Re:Betelgeuse Remains Steadfast in the Infrared
by atisu on Thursday February 27, 2020 @04:28AM
(#22431881)
Just for the record: the Dyson sphere is not an actual solid hollow sphere around a star. Rather it is a swarm of rotating objects orbiting the star.
Re:Betelgeuse Remains Steadfast in the Infrared
by machello13 on Thursday February 27, 2020 @12:05PM
(#22435155)
You're thinking of a Dyson swarm.
Re:Betelgeuse Remains Steadfast in the Infrared
by atisu on Thursday February 27, 2020 @02:17PM
(#22436726)
The naming is kinda misleading as Freeman Dyson envisioned the "Dyson sphere" as a swarm of objects. Although "sphere" is not technically correct, both swarm and sphere refer to the same thing here: a swarm of objects (e.g., O'Neill cylinders) orbiting a star.
Re:Betelgeuse Remains Steadfast in the Infrared
by machello13 on Thursday February 27, 2020 @03:27PM
(#22437412)
Huh, TIL. I always thought they were two separate ideas, not that the Dyson swarm is a type of Dyson sphere.
Re:Betelgeuse Remains Steadfast in the Infrared
by eric-hu on Thursday February 27, 2020 @03:45AM
(#22431696)
Why would a hypothetical Dyson sphere need to be in the habitable zone? I would guess that it should be built as small as the construction materials can tolerate.
Edit: I love that you did napkin math for this, BTW.
Re:Betelgeuse Remains Steadfast in the Infrared
by ncmncm on Thursday February 27, 2020 @08:39PM
(#22439833)
We can confidently predict that no one will ever find a Dyson sphere of any description. Anybody equipped to make one would have long since perfected controlled fusion, and spent the time fusing the nearest cold gas giant after mining out the actually frozen ones.
The place to look for aliens is around Neptune. Solar power (like goldilocks planets, and fission) is for extreme primitives.
r = 1AU gives a surface of 12.57 square AU (that unit boggles my mind as I write this)
r = 3.5 AU for Betelgeuse and the surface area is 153.94 AU. That 3.5 puts the sphere at the surface of the star.
The 8-20 cm thick surface becomes roughly 0.8 - 2 cm.
Betelgeuse is roughly 100,000 times more luminous than the sun (it is a variable star so I'm using a very round number).
The habitable zone is a function of luminosity only ( https://www.britannica.com/science/habitable-zone ). The approximation then is for the sqrt(L). For 100,000 this is 316. The habitable would be about 320 AU away from the center of Betelgeuse.
This gives the mind boggling large number 1.3 x 10^6 square astronomical units. The thickness of this material on the scale of proteins and Wolfram Alpha says it is about three times the approximate diameter of a carbon nanotube.
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Hoping to see a Dyson sphere around Betelgeuse would stretch the limits of physics. Or I've got my math off in a few places - which is quite possible.