<$BlogRSDURL$>

The Nacreous Oughts

30 November 2018

tired says it's last words 


New pwoermd.

20 November 2018

IZDUBAR 


(via darksands dot com)

So Barnard's Star does have a planet after all!

Behind that paywall, i would know more than its period (233 days) & mass (3.2 times Earth's), but using Hipparchos' visual magnitude 9.54 & parallax 0".54901, & 0.144 times solar mass (i had always thought around 0.15) & other info like stellar temperature (M4) 3134 K from Wikipedia...i get a visual luminosity of 1/4126 & (BC -2.10 [they seem to be using a bit higher]) bolometric of 1/596. Which makes this planet orbit just at 36.1 million miles (albeit varying 11.55 either way-- this orbit is eccentric), for a blackbody temperature of a little less than 91 K. That's cold. Ammonia would be frozen, even.

What kind of world is this, rocky, gaseous, or some unheard-of middle thing? I will just hazard that it is not as low density as Neptune (making it 2.2 times the size of Earth), & not as dense as a regular terrestrial planet of that mass (which would give it a radius of 1.4); the Galileans, with some 60% Earth's density, suggest a radius around 1.75, thence a gravity pretty close to Earth normal (1.05). At their albedo (50%), the graybody temperature is 76.4 K, & if there's a bit of a greenhouse effect (40, from methane), then one might reasonably expect a surface temperature of some -157 C. It's beginning to look a lot like Titan.

Not sure if the eccentricity means methane would be sometimes liquid, sometimes frozen & sometimes gaseous, but that's not a ridiculous scenario. It wouldn't be tidally locked (tidal effect is actually LESS than Earth: 0.954), & with a shrunken red sun providing about the same illumination (1/622) as our own sun does to an orbit midway between Uranus & Neptune, dark. If there were anything to Bode-Titius, this could be the fifth planet. Inhabitants, call them "dubars from Izdubar" & their culture "dubaric." Their 8-month-long "year" would have a pretty serious (even by local standards) "winter" portion. I can see them hibernating like bears.

-----------------------------------------------------------------------------------------
Revising the albedo to a Titan-ish 0.2, i get: -129 C at periastron (0.264120329 AU) & -159 C at apastron (0.512704168 AU). The sun just about doubles in apparent size (0.27 to 0.53). The lower temperature is comfortably above methane's freezing point of -182 C, while at the higher one, a pressure of 8.25 atmospheres is necessary to keep the seas (or lakes) from boiling.

19 November 2018

I, Uz bard 


(via, via Memories of Dallas)

From The North American Book of the Dead).

"I offered to use the moons of a gas giant [as a setting for my story]. ...I had to go back to the setting and work out the interactions of three moons, their parent planet, and the local star. ...the parent planet, a gas giant called Agamemnon, was big, and it looked big in the skies of its moons--about eighteen degrees in apparent diameter from the nearer moon, Orestes. ...the Oresteian day was 142.32 hours long...and Agamemnon eclipsed its star on a regular cycle, bringing a few extra hours of night in the middle of Orestes' long day. I already knew that a primary social issue in the novel [The Kindly Ones] was the existence of people who had been declared legally dead...I used that day/night cycle, and the eclipse at its center, to reinforce the division between the living and the legally dead 'ghosts,' deciding the legally dead could act legally only during the night and the eclipse." --Melissa Scott, Conceiving the Heavens (1997)

15 October 2018

ground control to major trump 


(via jim pike at memories of dallas on fb)

If there really was a book that contained the secret of life, it would not, assuredly, be called The Secret.

09 October 2018

the legend of woolly syrup 


(via)

Labels:

01 October 2018

forincon 


(theseastorm via)

Writers who use an extensive vocabulary (Ryling, A Theroux, Pynchon) are like microtonal composers; they just need more notes.

Rumi & "The Guests."

The Vulcan discovery paper finds an 8.47 earth-mass planet in a 42.378 day orbit around the star HD 26965 (omicron-2 Eridani A, HIP 19849, "Keid," HR 1325 & Gliese 166A), which is a triple with a white dwarf-red dwarf pair at 82" (some 418 AU), making one revolution in some 8000 years. The age of the system is given as 6.9 billion years--though the white dwarf may only be 122 million years old & must have been some kind of red giant before that (& then a "planetary nebula"--thought to be toxic for any nearby planetary life). Hipparchos gives the parallax as 0".1985657 & the visual magnitude of the K0 V primary as 4.43. It is metal-poor (Fe/H -0.42).

Some more general reflections...

Using a Bolometric Correction of -0.21 & a stellar temperature (given) of 5072 K, I get a visual luminosity of 0.373414809 & a bolometric luminosity of 0.453097366. (The radius works out to be 0.880224122--given as 0.87--so perhaps the BC should be a tad less.) With a stellar mass of 0.78 & a revolution period of 0.116022619, I find the semimajor axis of the planet to be 0.218974383. This gives a blackbody temperature of 490.3502805 (compare Venus at 328 & Mercury at 449): this is not by any means a habitable world! (Too bad nobody figured this in the dozens of news reports about "Spock's home planet"...)

If the planetary mass is 8.47 (given), its radius should be around 1.76; then I derive a density of 1.55, gravity of 2.73, & escape velocity of 2.19 times the Earth's (safely under the 3.19 that would hold molecular hydrogen at this temperature, thus producing a gas giant instead of a rocky world at start). The real question is how much of its original atmosphere will be left after its violent history with the evolution of 40 Eridani B (now 0.573 times the mass of the sun, but formerly at least an F-type star with some twice this). If I just plug in a low albedo like Mars's (0.15), I get a greybody temperature of 198 C. Greenhouse effect would presumably increase this. At surface temperatures such as this (I am ignoring for the moment the problem of a trapped--rotation climate), the atmospheric pressure must be at least 16 atmospheres for water not to boil. Would there still be this much left in the end? Could even a highly advanced civilization survive 10,000 years of living underground?

Labels:

07 August 2018

sqeqaize kozai 


(via)

"But the evening was only a 'debate' in the same way that Have I Got News for You is a 'quiz' or keepie-uppie is 'football'.."

Labels:

This page is powered by Blogger. Isn't yours?