<$BlogRSDURL$>

The Nacreous Oughts

27 August 2014

A super-Venus around Groombridge 34 


(via renderosity)

A planet 5 times the mass of the Earth has been discovered in a sub-habitable orbit around the brighter component of the nearby red dwarf binary Groombridge 34. Both components of the system (now known as Gliese 15, or HIP 475) are flare stars (GX And--with a range of perhaps 0.10 mag-- & GQ And). At a separation of 35" & this distance, the semimajor axis works out to be on the order of 146 AU [125 now] with a period of something like 2600 years [2014 if total masses are 0.48]. Nothing is known about the age of the system.

Hipparcos gives the parallax as 0".28027 & using visual magnitudes of 8.09 & 11.06 i get luminosities of 0.006439420308 & 0.0004176829744. The spectral types are variously given as M1e/M2 & M6/M3.5e. The main article uses T= 3567 K (which is K9 in my tables), R= 0.3863 solar, mass= 0.375 (given elsewhere as 0.414 + 0.08--i would say at least 0.40 for the former). Running some numbers from my own temperature & bolometric correction tables, i find a larger radius for anything cooler than M0.25: BC= -1.1775 T= 3387.5 & 0.019047885, with a derived radius of 0.404595231.

The planetary period of 11.4433 days gives a semimajor axis from 0.072 (M= 0.375) through 0.073 [they give 0.074] (M= 0.40) to 0.076 (M= 0.45). That corresponds to a blackbody temperature of 388, 384, or 375 K. For comparison, Venus is only 328. It would be difficult to avoid a runaway greenhouse, especially as the planet is substantially larger than the Earth.

Just how big? One equation i have, suggests that a rocky planet of 5.35 (min.) Earth masses, would have a radius of 1.56--this corresponds to a density of 1.41 & gravity of 2.3. Since the system is metal-poor (log Fe/H= -0.32), the density might well be less; if as little as 0.575, its radius would be 2.10 & its gravity 1.2. [The system being a metal-poor subdwarf, the anomalously high temperature of the primary sun is somewhat explained.] Log M/H (also given in the main paper) is -0.22 for density 0.684 (Mars is 0.71) is probably a more reasonable lower limit; this gives R= 1.985, & G= 1.35.

Undoubtedly the planet has synchronized its rotation. It does not appear to have been used much in science fiction (apart from video games) but it does have a neighbor less than 2 light years away--Ross 248, which Voyager 2 will pass not far from in 40,000 years; & which appeared in reference books since the 60s as possessing a "ghost planet" with a period of 8 years. That one we might as well call "Xzdjyk" (unless you like "Waughtal's Planet"). For Gliese 15 Ab itself, a case can be made for Tiryns...


(via atlas of the universe)

Labels:

09 June 2014

Kapteyn's Star 

Story of Kapteyn's Star from Sci-News.com on Vimeo.


Two planets have just been discovered around nearby Kapteyn's Star, an ancient metal-poor subdwarf in the constellation Pictor. With a visual magnitude of 8.853 and a parallax of "0.25566, the luminosity works out to 0.003832431762. Trying to match the radius as given, i figure this MO star with BC -1.0925 and T= 3450 K, for a total brightness of 0.01048273 solar, which gives a radius of 0.289370994.

Using a stellar mass of 0.274, the inner planet whose period is 48.616 days orbits at 0.169318524 AU, and the outer planet, at 121.54 days, would be 0.311887389. (Roughly this represents an orbital resonance of 12 to 5.) The corresponding blackbody temperatures are 217 and 160 K. However, their orbits are rather eccentric (0.21 & 0.23), so these numbers vary from 198 to 245 and 145 to 183. So even the inner planet is rather colder than Earth.

The tidal effect on these planets is 9.5 and 2.8, which leads to the consideration that the inner planet would either be captured, like several other "habitable-zone" exoplanets we have seen, or very long; by a rather complicated rule of thumb I have devised, i find the solar day of these worlds 674 days (22 months) long, and 10 days long, respectively. That would cause extreme temperature variations in the warmer world, moderated of course by the amount of atmosphere it possesses. But we know very little of what to expect with planets of a metal-poor, halo star such as this. One can extrapolate that the absence of heavy elements would result in a less dense planet overall; for instance, with metallicity (log Fe/H -0.86) of 0.138038426, it might be something like a fourth of Earth's. So the inner planet, with 4.8 times Earth's mass, might have a radius of 2.8 and a gravity of 0.63; the outer one, with 7.0 Earth's mass, R= 3.2 and G= 0.71.

If i assume the albedo of each world is 0.4375 and 0.51, and the greenhouse effect 50 and 60, the average temperatures (excluding diurnal variation), amount to -31.5, plus or minus 20.5 (due to orbital eccentricity), and -76 plus or minus 16 C. The outer planet might vary 10 degrees more either way if its solar day is 10, while the inner planet could vary by a hundred degrees more in the daytime, and less at night, with the slowly-rotating model. This is not a mild climate. It might be possible to find an atmospheric pressure such that water does not boil; certainly it would freeze long before sunset... The outer planet seems to be a bit too cold for an ammonia world; perhaps sulfur dioxide might work as a solvent there.

In addition to these changes, the star itself is a BY Draconis variable with a range of 8.90 to 9.22 magnitude; the variation is quasiperiodic, linked to the star's rotation period (195 days).

I am naming planet b Absamon, and planet c Maccasor (both names from the Sworn Book of Honorius). At closest approach (some 0.035 AU) each would show a visible disk, perhaps 1/4th the size of a full Moon as seen from Earth. From Absamon, Maccasor would have a synodic period of 81.0 days--a little less than an eighth of its solar day--but i would expect some kind of synchronization to have occurred.

[A synchronization of exactly 8 to 1 would make the rotation period 46.38 days, for a solar day of 1010 days. (7/14) --It takes 4 days for its sun to clear the horizon.]

Labels:

20 May 2014

Cendrillon 


The star now known as GJ 687, but in older lists of nearby stars BD+68°946 (also AOe 17415-6, Vyssotsky 322, & Ci[ncinnati 18h] 2354), in Draco, appears to have a Neptune-sized planet near the outer edge of its habitable zone. I am calling this one Cendrillon, for no very good reason, except that i've been reading multi-cultural versions of this fairy tale in some of my English tutoring. It is one of the closest stars to Earth, a M3.5 dwarf of either 0.21 or 0.413 times the mass of the Sun. At parallax "0.22084 & visual magnitude 9.15, its luminosity is 0.003907010002. For that spectral type, i would expect BC= -1.97, T= 3200 K, M= 0.32 (which gives a radius of 0.5), whereas the temperature given in the first, exoplanet discovery, source as 3413 K, corresponds to M0, BC= -1.12 & 0.50 times the solar mass (R= 0.3). The visual luminosity corresponds to a typical M1 star BC= -1.35 & 3350 K; its mass would be 0.45. They give the radius as 0.4183, & the best fit i can find is BC= -1.645 T= 3295 K (e.g. type M2.25--note that the B-V given as +1.5 in one of the sources is close to M2 standard) which gives a bolometric luminosity of 0.017776429 & a derived radius 0.413111619. (Not a bad fit for the larger mass.) These i will use.

If the stellar mass is 0.413 & the planet's period is 38.14 days, its semi-major axis works out to 0.165134804. The tidal effect is 15.145, so it is definitely trapped rotation. The blackbody temperature is 251 K, not much cooler than Earth's 279 K; trying some combinations of albedo, 0.19-0.36-0.51, with greenhouse effect 20-40-60, give average surface temperatures of -15, -8, -3. In short, this will be more "habitable" at the East Pole than anywhere near the terminator. There's a catch, though. Its mass is given as 18.394; thus there will be a strong tendency to hold molecular hydrogen at these temperatures (e.g. for any planet density greater than 0.336 times the Earth), & i expect this planet to have an ammonia-based biosphere, if any.

In Our Neighbor Stars (2012), Thomas William Hamilton writes: "The mass is 21% of the Sun's mass, but it has a much higher percentage of elements higher than helium than the Sun does [in Wikipedia i find: Fe/H +0.11; here +0.05]. This is generally taken to mean that the star is significantly younger than the Sun. ...It is a prolific producer of X-rays (also suggestive of youthfulness)..." Solstation has: "close binary? LHS 450" but no separate entry. Old books (ca. 1969) cite a dark companion, either 8-26 times the mass of Jupiter (1977), or 10-60. This is clearly another ghost planet, like those of Barnard's Star & 61 Cygni. Long ago i calculated Ci 2354 as a binary (period 26 years) with very high eccentricity (0.90). A separate, Earthlike planet close in is barely possible, but it does experience some wild gyrations of temperature. I wonder if everyone has forgotten this model?


(image via reneaigner on deviant art)

Labels:

07 May 2014

A Dissent on Odette 


(via phl dot upr dot edu)

The planet Kepler-186f (in Cygnus, which is why i call it "Odette") is being touted as the latest, most likely Earth-analogue yet discovered. While i like for these exoplanets to capture public attention, albeit ill-informedly (there's already talk of "going there"--as if 3 quadrillion miles were a Sunday drive), i have only just made a few preliminary calculations, without having seen the actual scientific paper.

At 492 light years, it's not in the immediate neighborhood. That makes a parallax of something like ".00662; which with an apparent magnitude 14.625 gives a visual luminosity of 0.028038933 solar. This looks to me like a main sequence star of about K8 spectral type. (We'll come back to that question.) When i plug in K8's 3800 K stellar temperature & the corresponding bolometric correction of -0.91, i get a total luminosity of 0.064827829 solar. However, the radius produced by these numbers is 0.59315683, much different from the 0.472 given by my sources. (They say the temperature is 3788, actually.) For the mass given as 0.478, my models suggest a visual luminosity of only 0.008 solar (with that apparent magnitude, the distance would better be at 263 light years.); that should be type M0.5 with a temperature of 3375 K, BC of -1.235, & derived radius 0.87387727 (total luminosity 0.087555618). I would put the mass at 0.52-0.53 instead.

Let's assume the distance is correct. the visual luminosity suggests type K9 (3600 K) BC -1.01 which gives total luminosity 0.071167878 & stellar radius 0.692457296, which i will provisionally use. We know the planet's rotation period is 129.94598 days. When i calculate the planet's semi-major axis from mass 0.52, i get a= 0.403748549 (they say "0.36-0.41"--good agreement). This works out to a blackbody temperature of 227 K.

Finding out the planet's real temperature from there is a matter of further supposition. If it has the same albedo & greenhouse effect as Earth (A 0.36, G 38 C) the average surface temperature is -32 C. That's between Earth & Mars, as we might expect. Assuming a thicker atmosphere (A 0.4375 G 50, A 0.51 G 60) makes it -26 or -23 C. In other words, we can make it a little warmer, but not a lot.

We know a little more; two things cause a reevaluation, to my mind, of our whole picture of this planet. First, the metallicity (log Fe/H) is given as -0.28, or 52% solar. I have long used a rule of thumb, not based on actual physical processes, but which makes it possible to assign a rocky-planet assumed density per the stellar metals. (A star of lower metallicity might produce less dense planets, all other things being equal.) If i adopt, by my rule, a planetary density of 0.616595001 times Earth's, with the observed radius 1.11 the mass will be only 0.84 & the gravity 0.68. So in effect it's a smaller world... Trying a more realistic A 0.2775, G 30 gives the average temperature of -33 C. This is distinctly "Barsoom-like".

It's being assumed too blithely that the rotation of this planet would be synchronous. But its tidal effect, 3.25, comes between Venus & Mercury, neither of which is captured (--Venus if anything is synched to Earth!); some of my calculations provide a likely rotation period of 1/10th its revolution period e.g. 13 days. So a "day" is a week & a "night" is a week. I estimate, with the lesser atmosphere (the actual amount of water being an extreme unknown factor), the diurnal temperature variation being on the order of 43 C either way, from 10 C to -76 C. In sum, a fairly slow rotator, heavy ice caps north & south, considerable day-to-night temperature extremes, with a big (1.7 solar apparent size) red sun in the sky... Odette.


(via kickass.to)

------------------------------------------------------------------------------------------
(Another formula i found gives, irrespective of stellar (& perhaps planetary) metallicity, the radius of a rocky planet is proportional to its mass by the power of 0.26 or 0.27; the derived mass for Odette becomes 1.482620868; then i get a density of 1.0840796 times Earth's, & gravity 1.203328357. Which means the albedo & greenhouse effect, & thus temperature, might be more like the exact earth analogue mentioned previously. Though the diurnal temperature variation would then be less, than the final number i came up with.)

Labels: ,

25 February 2014

katzenklavier 


(via)

Athanasius Kircher, in his own day another Leonardo almost, is remembered now (if at all) for his cat piano; & it would seem that Robert W Chambers--once the best-selling author of his time (several [silent] movies were made of his books, all lost)-- has left us only the Cheshire grin of his King in Yellow meme.

A new TV series has reignited interest (e.g. a recent Metafilter thread), & in a strange, very contemporary (dare i say "creepypasta"?) way, someone (on the inside, no?) has managed to reap a windfall from it. The first one on Amazon (the big seller, natch) dates back to September of last year. I count about 19 more from this month alone (out of copyright, doncha know-- i could add one for myself in about twenty minutes through CreateSpace). These are all his own words. What's of greater interest, to me, is the unwritten part of his work: the infamous play which he refers to (& briefly quotes from) but never himself (so far as we know) bothered to complete.

Other writers have tried to fill that lacuna: the redoubtable James Blish, Lin Carter, Thom Ryng (whose version, bad as it is, has actually been performed, in Seattle; even one by yours truly. (There have also been film incarnations; perhaps the most artistically significant result in all these referencings is a certain King Crimson album.) I see this as a definable literary practice ("zoomars"--i was first inspired by Arthur Machen's The Three Impostors--which has nothing to do with the ostensible subject of the original non-existent book!). I have followed this up with my own interpretation, for instance, of an imaginary longpoem described in a Galsworthy novel, not to mention The Theory and Practice of Oligarchic(al) Collectivism. (Perhaps one day i will write The Grasshopper Lies Heavy.)

Should one desire to delve, there is more to this than copycatting, sub-Lovecraftian frisson, or the findesecular flavor RWC himself barely hinted at. What terrible book lies behind the threat to society, even to one's individual identity? Darwin? Freud? Marx? (My money's on Nietzsche.) Nowadays we find it easier to believe in life-altering movies, as in House of Leaves or Pessl's Night Film. These are all, in a way, allegories about the power of art; in our own era this figures most prominently as the counter-culture conversion experience of the Sixties, viewed as destructive only by those who disapproved. A truly Dark Enlightenment would have to resemble Hitler's (chillingly self-described, in Mein Kampf) conversion to antisemitism. Madness, yes, but is it Art?


(via)

"...the moon looks like a yellow jewel, like a strange yellow jewel from some dead king's crown." --Firbank

Chambers postscript.

Did somebody say "Rach 3"?

Labels: ,

14 February 2014

DJ Snoopsagan 


If one of the characteristic artforms of our era is glimflash (recasting one artwork in the style of another--a practice dating back to the very origins of genres), a second is the mashup AKA "plunderphonics." Among these, i have been particularly fascinated by the possibilities which newly matching disparate soundtracks & imagery evokes--this i dub Zi, e. g. "Watching Incubus to Dir en Grey." I started thinking along these lines in the early eighties--around the inception of "music videos" though i never watched them till years later ('91-'92)--& even then i was earmarking certain self-contained sequences in movies that i liked (the openings of Exorcist II & Bram Stoker's Dracula.)... Later I acquired a boxed set of 50 B- & (C-) sci-fi movies, & began watching them with the sound off, playing whatever music i happened to feel like. Alongside, i began collecting unusual cover versions of favorite songs (especially "Eleanor Rigby," which i eventually assembled a mixtape of), & understood the activity of translation itself in a similar light.

The aesthetics of juxtaposition can be roughly plotted on a continuum from "illustrative" (100% perceived congruency) to "ironic" or "paradoxical" (100% contradiction); these extremes are less interesting to me than the degrees inbetween, which might be called Fifty Shades of Parataxis. The point is to make something more than the sum of its parts. The ending of Dr Strangelove, combining an atomic mushroom cloud with the song "We'll Meet Again," stands on its own as an independent artwork even without the satire that preceded it. James Joyce's later works are full of such creations (moreso than Pound or Pound's Eliot). (--I think Vallejo might benefit from such a reading.) Others are almost canonical: "Old Time Rock 'n' Roll" from Risky Business; "Flight of the Valkyries" from Apocalypse Now (even though this purports to be what's actually happening on-screen)... Does the "Thus Spake Zarathustra" part of 2001: A Space Odyssey qualify? Nina Simone's "Sinnerman" at the end of The Thomas Crown Affair remake? To some extent, the latter two are part of the story-telling. (Ditto "As Time Goes By" in Casablanca--thanks, Melanie, for the suggestions!)

Sometimes movie trailers stumble upon something that works better than the movie itself. I remember well when Hope Floats featured Live's "Lightning Crashes" for its dance-&-fireworks sequence of the trailer. And the teaser-trailer of The Fifth Element with its haunting Bulgarian Voices soundtrack...

This has been much facilitated of late (videodoubler & youtubedoubler dot com, possibly others), & i have started at last to act upon these notions. The first one i attempted was Joseph Cornell's (itself appropriated) "Rose Hobart" combined with an album by Balam Acab--Cabadath3. (I made another first--the mysterious "Suicide Mouse" plus Daphne Oram's "Four Aspects"--for practice.) I happened to be listening to the one as i was watching the other &--it fit.

Cabadath4 combines a certain sequence of real-life Wikileaks footage with the famous theme from The Good, the Bad, and the Ugly. Maybe i should hasten to add, i don't ordinarily approve of "snuff flicks," but one may ask whether this is any more outrageous than the fact of a war that has gone on for more than ten years against people who never even attacked us. I guess i hope the Zi transcends the politics of the day.

(What ought to be) Cabadath6 is, i think, one of my most perfectly realized Zis so far, joining the deserted amusement park sequence in Carnival of Souls with Sarah McLaughlin's "Possession." Here the transitions in the song mirror changes in the image-stream.

I'm not entirely satisfied with Cabadath7. Certainly i find everything from the silent era both haunting & semiotically versatile. But the subtitles are a bit of a distraction here. Caretaker (or any other hauntology artist) seems almost a cliche; still, you put it together with something contemporary & it's just low-fi. As it happens, the band Year of No Light has scooped me with an entire soundtrack to one of the greatest silent movies, Vampyr.

Continuing with Dreyer, i found a short, abstract film of his that works pretty good with some Pierre Henry. Musique Concrete is one of my less shareable loves. Parts of my 1983 viddy ORG/N/ISM attempt something such as this.

I have a love/hate relationship with Pulgasari. In Cabadath9 i add Burial's "Be True Black Swan," though i'm not crazy about where i begin & end the visuals. It may be debated whether some wizzier music would be best for this lugubrious melodrama.

Cabadath10: Salem plus X the Unknown. Cabadath11: tornado footage plus Throbbing Gristle.

There is, of course, no end to these experiments. Not all of my favorite songs require visual accompaniment. But wouldn't "House of the Rising Sun" work with some selective post-Katrina footage? And where can i find images that can live up to "Leftover Wine"?

----------------------------------------------------------------------------------------------------------

I would be remiss if I did not mention here Momus's project with Murnau's Faust, or the W**d* *ll*n movie What's Up, Tiger Lily?...& I might as well add: neo-benshi. We won't even get into Dark Side of the Rainbow...

Labels: , ,

22 October 2013


Out of a thousand...(via)

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