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  The Vast Polar Structure & not Dark MatterMay 22, 2012 1:45 AM PDT | url
 
Added 1 new A* page:Last update I talked about one of the leading silly theories in astronomy having taken a knock based on new studies--that idea being the one saying that the Moon resulted from a "Mars-sized" mystery planet hitting the newly formed Earth, its core sinking into and merging with Earth's, and the other lighter crust stuff blowing off and eventually congealing into the Moon--a big reason for the existence of this theory being measurements indicating that the Moon has an unusually low-metal core. I'm a big believer that the simplest explanation is usually the best, and while I don't have my own particular theory about the Moon's formation, I do know that hitting the Earth with a whole other planet is not a simple explanation. Well then, imagine my further delight when an even bigger silly theory in astrophysics, again based on trying to make measurements add up by inventing something completely out of the blue, took another big knock: that theory being the whole "Dark Matter" business.
 
Dark Matter, as far as I understand it, came out of calculations showing that the stuff we can see in the universe around us doesn't add up to nearly enough stuff to fit our current best model of the universe, the big bang and all that--the conclusion being that there must be a whole lot of stuff out there we can't see. That sounds plausible enough; the problem came, maybe, when people really latched onto this sexily named "Dark Matter" and started making up whole cosmologies about it being this mystical new energy substance permeating the universe and explaining everything; it's hard to go a month without seeing some new pop sci article about some new dark matter simulation showing how such and such galaxies might do blah-de-blah. That's great and all but it's all founded on missing pieces and inference--yet a lot of people have been getting carried away about it and, perhaps worse, convincing a lot of other people, even scientists, that "Dark Matter" was pretty much a done deal--never mind that we've never even caught a glimpse of the stuff, and no, gravitational lensing around blobs we can't see scattered far off in intergalactic space doesn't really count as far as I'm concerned. :P
 
So I'm very, very glad to see this astrophysics research paper: The VPOS: a vast polar structure of satellite galaxies, globular clusters and streams around the Milky Way. In it, its authors, from the University of Bonn, in Germany, describe the discovery of this:
 
video on Youtube
 
That's a basically a roughly disc-shaped group of globular clusters, star streams, and "tidal" dwarf galaxies that appears to be orbiting the Milky Way, but nearly perpendicular to the galactic plane, and extending as much as twenty times farther out than the Milky Way's starry arms.
 
Boy! That's certainly something. What's it doing there? Well, their best guess is that it's debris from a collision, or near collision, between the Milky Way and another large galaxy about 10 billion years ago. MAN. The paper says:
 

We suggest that the MW has experienced a near-polar collision with an approximately perpendicularly oriented disc galaxy. Figure 6 illustrates this geometry with images of observed interacting galaxies and two model snapshots. They show that polar interactions of perpendicularly oriented disc galaxies happen even at the current epoch and result in tidal debris distributed in a polar structure.
 
The initial interaction could have been a fly-by of two galaxies or it might have ended in a galaxy-merger, destroying the infalling galaxy in the process. In a major merger, the two colliding galaxies will form a spheroidal object. As this event must have happened about 10 Gyr ago, the MW disc might have re-formed from gas accreted later (Hammer et al. 2005), with the spheroidal component being the bulge of the MW today. Ballero et al. (2007) estimate that the MW bulge must have formed rapidly on a time scale of 0.1 Gyr, in favour of a merger-induced origin. However, also in a fly-by encounter material stripped from the passing galaxy would be accreted onto the MW, possibly producing a bulge component. A bar instability would in any case channel gas onto radial orbits.
 
If the TDGs were not formed in a merger but in a flyby encounter, the passing galaxy still has to be nearby. Two candidates can be found in the Local Group: Andromeda and the LMC.

They go on to cite previous studies into the possibility of our satellite galaxies being the result of close encounters with the Large Magellanic Cloud, one of the classic 12 satellite galaxies of the Milky Way, and about 1% of its mass, as well as the Andromeda Galaxy, which is much further away (2.6 million light years), predicted to encounter (or re-encounter?) the Milky Way in about 4.5 billion years, and the member of the Local Group of galaxies with the most stars--1 trillion, about twice as much as the Milky Way--but strangely, recent studies have shown it to be perhaps only roughly equal to the Milky Way in mass.
 
That must mean the Milky Way has more Dark Matter! Well, no, says this study--that matter can be found in all these newly discovered dwarf galaxies in the disc above and below the Milky Way, and, furthermore, that disc contradicts the prediction of the best Dark Matter "models," which call for the stuff to be distributed around the outskirts of the Milky Way in a nice spherical, mystical "halo."
 
So, sorry, Dark Matter! This actual debris disc is much more interesting, AND much more convincing--well, I can't speak for scientists, but it certainly is for the layman such as I. I'm sure Dark Matter proponents will regroup and come up with some way around this problem, just as the Loonies have done with the study showing the Moon is made of the same stuff as Earth, and probably not a mystery planet's crust, but hopefully it will get at least *some* research directed back toward actual stuff.
 
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(I suppose you could ask why I like that Milky-Way-hit-by-other-galaxy theory but detest the Earth-hit-by-other-planet theory, when they're roughly similar methods of explaining things, in a way. I guess a) the galaxy theory actually points to existing candidates for the hitter, whereas the planet theory has nothing to point to, except to say that the planet was neatly swallowed up into the Earth and the Moon, b) there really isn't another way to explain that huge disc of dwarf galaxies, plus it fits with what we can see in other galactic collisions, whereas with the Moon, there *are* other, less complicated explanations, even if they aren't completely worked out yet either, and c) the galaxy thing would solve more questions than it raises--it would help explain Andromeda's own distribution of satellite galaxies, for instance, and its relative lack of mass--whereas the planet one...well, wouldn't such an impact just have destroyed the Earth--blown it apart, I mean? Or at least affected its mass/velocity enough to knock it into a different orbit and, in general, just throw the planet way, way out of whack? And where would other planet have come from, anyhow, and why would it have crossed paths with the Earth? Etc! Well okay I should stop arguing so much about things I really don't know anything about, yeah. I'm just an artist, damn it! :P)
 
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I came across a pretty good article on inking by MAD Magazine, etc artist Tom Richmond, in which he gives a detailed study of his work inking a large illustration.
 
He also shows how he uses his drawing board--propped up between his lap and the edge of his drawing table--and this has made me think I should go by the art supply store tomorrow and pick up an actual proper drawing board, because the one I have now isn't very long, which means that when I prop it on my legs to draw, it's leaning off a point about mid-thigh, instead of back near my body, at the top of the thigh--and I think this is becoming a problem, because it means my drawing arm isn't braced along a flat surface from elbow to brush, so my wrist is being bent downward; anyway, once in a while, like after today's intense feathering of all those little shadow lines, my wrist will be hurting, and that isn't cool. So we'll try a real art board!
 
I've also been thinking that maybe a wider grip on my brush would help--wider grips are supposed to take less energy to hold, anyway--but I can't find anything like add-on wide gripper things for brushes as exist for, say, pencils. So I think I'll get some kneaded erasers (they're sort of thick, grey, silly-puttyish stuff you can mold) to put around the narrow grip area of my brush--if a real drawing board doesn't completely solve the wrist thing, anyway. I'm also wondering if maybe I could fit the brush itself--possibly with the non-bristle end sawed off short--into a 5.6 mm lead holder. My size 4 Raphael 8408 brush is about 5 mm at its widest handle point, although it narrows to closer to 2mm down near the bristles, which is where you actually want to hold it. So, not sure that would work, but if it did, then I'd have a nice thick handle! Hm there's also things like crayon or chalk holders, but those seem to be even bigger; the chalk one is for 3/8th inch diameter chalk, whereas my brush is about 1/4 inch. So I'm not convinced those would work. You'd *think* someone would make an add-on wider grip for brush handles, but darned if I can find one.
 
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Here's a sketch I did over the weekend with the Pentel Pocket Brush--I was reminded of it when I read superhero comic book inker Hilary Barta saying he inks with the similar Pentel Color Brush in Gary Martin's "The Art of Comic-Book Inking" that someone just got me off my A* Amazon Wish List last week. :) Barta gets really sharp lines with his, though (he just dips it in his own ink rather than using Pentel's cartridges--which would seem to defeat the purpose for which most people use brush pens, ie their portability, but he says he just likes their wider grip (I can see that!) and that they're cheaper than sable brushes). You'd think a pro who gets like $100 per inked page wouldn't mind paying $20 or something for a nice sable brush that would last them probably fifty pages or so, but I guess you gotta save money wherever you can. :P
 
Oh right, the sketch:
 
Image
 
If you cover up the nostrils and mouth, which were drawn early on, when I thought I was doodling the face head-on instead of slightly to the side (faces have a way of twisting on me if I'm not being careful :P), then it looks pretty okay! I like how the secondary-light-source type shading came out, anyway, and the hair. Maybe a soft, mushy brush like the Pentel is actually good for those! It is pretty handy for quick, small brush doodles, at least.
 
Here's what's on the back of today's A* page:
 
Image
 
That big part in the lower middle was the first layout I did for the page, but it ended up feeling a little too square-on Selenis' back--she's blocking the view of the knife, for one thing, and it's a bit too balanced to feel really dynamic. So I knew I'd flip the page over and start again on the other side, but first I used of some of the remaining space on this first side in practicing other layouts--the one in the upper right was the one I fixed on to try.
 
 
 
 
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