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PostPosted: Tue May 23, 2017 4:56 pm 
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Agemegos wrote:
Those are salt ponds, and the colours are photosynthesising halobacteria — ones that use retinal and rhodopsin rather than chlorophyl. Let those rather than cyanobacteria become endosymbiotes or evolve multicellular forms and you would have just such orange and magenta leaves.

How novel, are they growing the bacteria specifically, or is having some salt containment the key part? I will have to research this; I've never heard of it except in some aboriginal societies where they gather salt from sea water for trade. Thanks for clarifying the photo!

(Ahh... and now I found your pic. Exactly what they're still used for. And, with a handy color guide to salinity growing within!)

The Purple planet hypothesis mentions retinals as the photon capturing chemical.

Thanks for the article, thrash. So much to read...


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PostPosted: Tue May 23, 2017 11:10 pm 
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Baron Opal wrote:
Agemegos wrote:
Those are salt ponds, and the colours are photosynthesising halobacteria — ones that use retinal and rhodopsin rather than chlorophyl. Let those rather than cyanobacteria become endosymbiotes or evolve multicellular forms and you would have just such orange and magenta leaves.

How novel, are they growing the bacteria specifically, or is having some salt containment the key part?

I gather that they are evaporating seawater to obtain salt and perhaps other minerals. The salinity of the ponds is too high for most forms of life; it kills algae and cyanobacteria. The salt-tolerating extremophiles that survive happen to photosynthesise using retinal, and the absence of green photosynthesisers (a) allows them to proliferate to an degree seldom seen elsewhere and (b) makes their colour obvious because is not mixed with green as usual.

I don't know, but I suspect that the orange colour of some of the ponds is the result of their still having a small proportion of chlorophyll-bearing and carotenoid-photosynthesising organisms in them.

Quote:
I will have to research this; I've never heard of it except in some aboriginal societies where they gather salt from sea water for trade.


Salt is obtained commercially both from mineral deposits and by evaporation of seawater. There are some very large salt ponds in Western Australia — e.g. at Karratha, Onslow, and Useless Loop — where the product is scraped off the bed using large bulldozers. The evaporation ponds at Onslow are large enough to be visible from orbit.

Start your researches with the Wikipedia article on "Salt evaporation pond"

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Last edited by Agemegos on Tue May 23, 2017 11:44 pm, edited 1 time in total.

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PostPosted: Tue May 23, 2017 11:43 pm 
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thrash wrote:

Very interesting! It suggests planetary systems in orbit around neutron stars that, rather than surviving the supernova, form by accretion in the debris disk after the supernova.

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PostPosted: Sat May 27, 2017 1:14 am 
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Baron Opal wrote:
Is it possible to have extant planetary systems around a black hole?

If I remember correctly, you need an O-type, or at least a fat A-type, to have enough mass to collapse into a black hole. Because of the intense and energetic radiation, the local disk is likely to be swept clear of dust and debris out to the Oort Cloud. Then, when the star goes into giant phase and then novas, the shockwave would clear out anything that was nearby anyway.

I'm putting together a scenario where a jovian (now cthonic) with habitable (sorta) moons is around a black hole, but I've gotten the feeling recently that it crosses the line from "infintesimal, but non-zero" to "no, this is fantasy". Note: I can work with that, but I do want to know what foundation I'm building on.

What do you think?

Well, I think something different today than I thought yesterday: it seems that massive stars quite commonly form black holes without going through a supernova: https://www.sciencedaily.com/releases/2017/05/170525141532.htm.

It's not clear that this can happen to a star low-mass enough to last long enough to form planets and moons around its jovians before it goes. But I guess that material in its its circumstellar disk would go on accreting, migrating and so forth after the lights went out.

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— Brett Evill

My SFRPG setting, Flat Black

© My posts to this board are copyright under the Berne Convention. They may be quoted on the board with appropriate attribution. They may not be reproduced beyond the board except with explicit permission from me.


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