A very pretty time-lapse video of the northern lights:
You may recognize the uploader there as the same one responsible for the neat video of the Milky Way spinning in the night sky that I posted a while back.
The northern lights, or aurora borealis ("named after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas, by Pierre Gassendi in 1621") are what happen when charged particles from space--mostly from the Sun, I should think--zoom in along the lines of the Earth's magnetosphere and crash into the upper atmosphere at the planet's poles. There are also southern lights--"aurora australis," to use the old tongue--and you can see in an interesting superimposed video on NASA's Earth Observatory site (Quicktime format :P) that they, like their northern mirror image, form a pulsating hoop around the pole. And there are aurorae on other planets, as I've shown before, for instance here.
They are neat.
Our second video today is a time-lapse of the skies wheeling above the ESO's Very Large Telescope array high up in the mountains of Chile--lots of good views of the Milky Way:
One thing I thought was particularly nifty in that video is that you can see the VLT's laser star guide--the thin orange line--firing into the sky; it excites sodium atoms in the mesophere, about 90 km up, causing them to glow; this glow is used as a reference--an artificial star--for the telescope's sophisticated adaptive optics, which can then manipulate the incoming light from stars--or whatever the VLT is looking at--to correct for distortions caused by the atmosphere, having read the distortions very precisely from the known quantity of the light coming back from the laser-initiated glow.
But it's also fun to imagine it's shooting down incoming Klingon battle cruisers.
The supermassive black hole known as Sagittarius A*, of course, is located in the center of the Milky Way, and you could see it in that video, kinda, except that it's blocked by gas and dust, and also is probably nearly invisible a lot of the time anyway. But the VLT was one of the instruments used in the rather famous study of A* and the galactic core by the Max-Planck Institute that culminated in 2008 with this time-lapse footage showing the orbits of the stars closest to the center of our galaxy turning in tiny loops, which could only be due to the presence of a supermassive black hole--so that was pretty much the proof of A*'s existence.
Here's an ESO video sort of zooming in from a typical view of the Milky Way to those central stars. This is their article about the study and their part in it; I thought this quote from one of the lead Max Planck team members was interesting:
Quote:
The stars in the innermost region are in random orbits, like a swarm of bees," says Gillessen. "However, further out, six of the 28 stars orbit the black hole in a disc. In this respect the new study has also confirmed explicitly earlier work in which the disc had been found, but only in a statistical sense. Ordered motion outside the central light-month, randomly oriented orbits inside – that's how the dynamics of the young stars in the Galactic Centre are best described."
And since every article needs a picture, here's a VLT photo of the galactic center in the near-infrared (the part of the infrared spectrum closest to visible light), with A* somewhere in there:
As I was walking home from a friend's house this evening, gazing idly at the Big Dipper and imagining that I could almost see the supernova at the tip of the northward-facing equilateral triangle you can form from the last two stars in the constellation's "handle," the word "hypernova" popped into my head, so I figured I'd write something about it, because it's a pretty cool word.
A hypernova is simply the explosion of a very large--or "hypergiant"--star: one 100 to 300 times the mass of our Sun. There haven't been very many of these that have been observed well enough to make for pretty pictures, but I did find the case of SN 2006gy, which was, at the time it was discovered in 2006, "the brightest stellar explosion ever recorded" (the next year it was found to have been trumped by one that took place in 2005, but much further away--4.7 billion light years). SN 2006gy took place in galaxy NGC 1260, 238 million light years away, and seems to have been "an unusually high-energy supernova of a very large star, around 150 solar masses." Here is what its X-ray emissions looked like to the Chandra X-ray telescope: that's SN 2006gy's X-ray emissions in the upper right, and all the X-rays from the core of its galaxy in the lower left:
So as you can see, that hypernova of a single star was almost as bright an X-ray source as the entire core of its galaxy!
SN 2006gy is also kind of interesting because scientists have theorized (among other ideas--but this seems to be the front-runner) that its explosion wasn't just the old fashioned kind of supernova, where a star runs out of fuel and collapses, with the collision of its mass resulting in a huge explosion. No! They think that it might have been the first observed pair-instability supernova, which could theoretically happen in stars of between 130 and 250 solar masses. In this case, it wouldn't have been the star running out of fuel that would have led to the explosion; instead, the star would have been in full nuclear swing, and the energy it was emitting--as high energy gamma rays--would have become so intense, due to the star's incredible size, that the gamma rays would, if they struck an atomic nucleus inside the star, contain enough energy to undergo pair production, ie turning from a huge amount of energy into matter: an electron and its opposite, a positron. Einstein's famous E=mc² in action (well, maybe specifically as m=E/c²)!
If that started happening to a lot of the star's energy output, the star would be losing heat (energy) and wouldn't have the bubbling nuclear force to hold itself up--so it would undergo partial collapse. But the sudden pressure increase of this collapse would enable nuclear fusion to burn all the star's fuel in seconds, resulting in a really huge explosion that would blow the giant star entirely apart--not even leaving a super-compressed white dwarf or black hole behind. Also,
Quote:
In addition to the immediate energy release, a large fraction of the star's core is transformed to nickel-56, a radioactive isotope which decays with a half-life of 6.1 days into cobalt-56. Cobalt-56 has a half-life of 77 days and then further decays to the stable isotope iron-56. For the hypernova SN 2006gy, studies indicate that perhaps 40 solar masses of the original star were released as Ni-56, almost the entire mass of the star's core regions. Collision between the exploding star core and gas it ejected earlier, and radioactive decay, release most of the visible light.
Wed Sep 07, 2011 2:04 am
sunphoenix
Joined: Thu Nov 18, 2010 11:51 am Posts: 82
Hmmm... interesting reaction to the situation by Selenis. She has never shown herself to be... necessarily a 'prideful' woman... or 'vain'... per se. I find myself wondering why does she care what the drones of the office or grunts in security think about her at all? They have no idea who she really is so why would their opinions matter at all? Plus, if everyone suspects her and the Boss Mr. Adrian are... intimate, will that not make it that much easier for her to get close to him and connive his 'accidental' death?
I had always assumed that Selenis was the consummate PRO... and her beauty, if need be, was as much a deadly weapon as her fighting skills. If it seemed that it would take sex to kill a target more efficiently - it was just another weapon she would use... no issues.
Interesting... so there are some things she will not do to succeed!
Or is it something we have not seen yet... perhaps she has some personal hang-up about sex or the image of being in a sexual relationship for other reasons of her own?
We as viewers really don't know what Selenis does in her free time... if such a thing exists for her, or her preferred sexual 'orientation' or lack thereof.
Wed Sep 07, 2011 6:32 am
BC
Joined: Fri Mar 13, 2009 4:18 pm Posts: 2858
:) The ending of this episode will sort of answer some of those questions. Hm... Well, it will probably leave you with even more questions, but hey. :D
Apparently I should Google my own comic more because I tried it today and found some nice things people said about me some time back! Antionestrife of the I Am Legend blog wrote a very nice review of A* (and they said nice things about the site's navigation system! *swoon* <3) last December. And Beertycoon of the webcomic Maskerman, who has helped me out a few times in the past with feedback on the site, wrote a neat little review of A* on StumbleUpon a while ago. Many belated thanks, guys!
~~~~~~~~~~~
Yesterday I was talking about hypernovas, which are huge supernova explosions that can happen to some of the very biggest stars around. One such star that some have said might be the closest candidate to us for a hypernova is the huge binary (or cluster) Eta Carinae, 7,500 to 8,000 light years away in the Carina Nebula. It is about four million times brighter than the Sun, although 99% of that energy is in the infrared. You can see it as the brightest star (near the top) in this mosaic of the Carina Nebula, taken by the ESO's La Silla Observatory in Chile:
image by ESO/IDA/Danish 1.5 m/R.Gendler, J-E. Ovaldsen, C. Thöne, and C. Feron. (source)
Eta Carinae used to be even brighter and more massive, though; it is currently believed to be composed of at least two stars: a luminous blue variable ("LBV") of about 100 or 120 solar masses, depending on which source you read (and is believed to have lost an additional 30 solar masses in the past), and a Wolf-Rayet Star of about 30 solar masses; both of these types of stars are so energetic that the radiation they generate overcomes even their massive gravity, and blows their stellar material out into space in vast quantities. The combination of these stars in the Eta Carinae system has shed enough mass to form its own sub-nebula inside the 60-light-year-long Carina Nebula: the smallish but spectacular Homunculus Nebula shrouds the stars in mystery, as you can see in this Hubble mosaic combining red visible light and near-infrared, and adjusting the dynamic range so that you can see both the bright central stars and the cloud around them, which is actually 100,000 times dimmer:
Most of that cloud is actually thought to have come from a nova explosion in 1841; by 1843, Eta Carinae was the second brightest star in the sky--second only to Sirius, which at just 8.6 light years away is nearly 1000 times closer to us. Scientists can tell that it was an extremely powerful explosion, just short of a supernova that would have destroyed the star, due both to the amount of matter ejected in those nebulous clouds, and to their speed: they are moving outward at 1.5 million miles per hour, or 0.2% the speed of light; but that's less than half the speed of clouds expanding outward from true supernovae. Aside from that peak, Eta Carinae has gone through many cycles of dimming and brightening since its luminosity was first catalogued by Edmond Halley in 1677; these cycles are thought to have to do with fluctuations and eruptions in its stars.
In fact, some scientists conclude that the unstable star system is due for its final supernova, or even hypernova, in a "mere" 10,000 to 20,000 years. If it does eventually explode in a hypernova, it might be bright enough to be seen during the day, and its radiation could pose a threat to spacecraft and satellites in Earth orbit. If it shot beams of intense gamma-ray bursts from its poles, as can happen in such explosions, such a beam hitting Earth would subject those on the surface to 10 times the lethal dose of radiation; even if it did go hypernova, though, the chance of it happening to point its gamma ray burst directly at Earth is infinitesimally small--maybe even downright impossible, since its poles don't point in our direction. But don't let little details like that stand in the way of a good doomsday theory!
Aside from the extremely unlikely event that it might turn itself into a death ray bent on our destruction, considering that the star types making it up are very rare--there are only 20 known luminous blue variables, and only 300 known Wolf-Rayet stars in our entire galaxy--we're very lucky to have such a cool star system so close by to observe. I suppose I might not be saying that if it did explode and knock out satellites and cable TV and the internet, and maybe screw up the ozone layer a bit more than we are already doing...but come to think of it, that explosion would probably look totally rad. Besides, in 10,000 to 20,000 years, humanity will probably have way bigger problems on its hands. =p
I came across a new AP article today about a child diagnosed with progeria, which has been called an "aging disease"; a genetic disorder caused by a mutation, a baby with progeria will go from having the symptoms of a small, weak newborn more or less straight to the symptoms of a small, weak elderly person; people born with progeria rarely live into their mid-20's.
I hadn't known about progeria before, and I found it interesting in terms of A*, because in order to produce adult clones within the lifetime or near-lifetime of the person cloned, which...well, it saves the story a lot of waiting around, you know, and besides it would be a lot more efficient...anyway you need something Selenis once called "accelerated aging."
Progeria definitely wouldn't be what you would want for that, since it doesn't produce any sort of robust adulthood between birth and death, but it at least shows that one or more of the mechanisms that may be responsible for aging can be sort of sped up. The Wikipedia article on the disorder, which I linked above, says it operates as follows:
Quote:
The LMNA gene is responsible for producing lamin proteins, which provide strength and stability in cells. Lamin A and Lamin C support the nuclear envelope. When Lamin A is altered, it affects the shape and the function of the nuclear envelope. These changes cause other cells to die prematurely.
Unlike "accelerated aging diseases" (such as Werner's syndrome, Cockayne's syndrome, or xeroderma pigmentosum), progeria is not caused by defective DNA repair. Because these diseases display what are considered different aspects of aging, but never every aspect, they are often called "segmental progerias".
So in fact there are a whole host of such genetic disorders, prematurely causing various problems usually associated with old age. And there's a name for the scientific field dedicated to studying the biological processes of aging: biogerontology.
Those disorders, though, tend to deal with the, well, negative aspects of aging, rather than what Selenis would be interested in using, namely accelerated bone, muscle, and organ growth, accelerated onset of sexual maturity, etc. And ideally you would want to be able to regulate them a little--once the clone was close to the desired "age," you'd want to put the brakes on a bit. While I don't at the moment know of methods or even disorders that mess with the timing of such biological processes, there must be some sort of biological mechanism(s) controlling their rates, and somehow to me it doesn't seem too far-fetched to think that some day someone--perhaps a somewhat amoral someone, I suppose =p--might be able to manipulate them a bit.
~~~~~~~~~
Anyway that wasn't even what I meant to talk about today, although the main topic is going to involve not so much talk as a big picture, so perhaps it's just as well that I had a wordy but un-illustrated subtopic to partner with it. The bandwidth-heavy topic, then, is the Carina Nebula, home of the huge and somewhat unstable Eta Carinae star system that I was talking about yesterday.
It is a very large and bright nebula, but doesn't grab as many headlines as it should perhaps because you have to be in the southern hemisphere to see it. Fortunately though Hubble can see it for those of us in the wrong hemisphere--and see it quite well, since it's "only" 7,500 or so light years away; I've always liked this false-color mosaic of the whole nebula taken by Hubble, where "red corresponds to sulfur, green to hydrogen, and blue to oxygen emission":
image by NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA) (source)
^ That is about 50 light years from top to bottom. Eta Carinae is the really bright star in the middle of the top half. The complicated cloud below it is called the Keyhole Nebula. And the brightest star in that cluster of bright stars in the middle of the bottom half is HD 93129, a binary system which really should have a cooler name, since its component hypergiant and supergiant stars weigh in at a collective 200 solar masses, which is much heftier than Eta Carinae. It has fewer issues and causes less drama, though, so, you know--squeaky wheel and all that. Poor HD 93129 gets no respect, I tell ya!
(Wikipedia has a map of the Carina Nebula over here.)
Incidentally, Hubblesite, which as I mentioned a week or so ago is run by the Space Telescope Science Institute (STScI) under contract from NASA, has a neat zoomable version of that image, in which you can zoom in to much higher detail than I was able to fit in the confines of this column!
Their source page for the image has some interesting info about the nebula: it is thought to have started as a huge cloud of hydrogen gas; it clumped together in spots which ignited into stars about 3 million years ago (quite young for stars, considering that our own Sun is over 100 times older: 4.6 *billion* years old!), and those started blowing the surrounding gas and dust into interesting shapes; that outrush of material is now compressing against the cold hydrogen enveloping the nebula, triggering new waves of star formation. The article says "In looking at the Carina Nebula we are seeing the genesis of star making as it commonly occurs along the dense spiral arms of a galaxy."
Yesterday I posted a really big picture of the awesome Carina Nebula. That was about as much bandwidth as I thought I should leech from you for one day, but there's plenty more to be seen of the nebula! So today let's zoom in on some pretty spots with the help of Hubblesite's gallery:
A closer (and I *think* true color; the false color version is here) view of the intricate peaks of gas in the star forming region visible in the lower right of the big image above; the gas is being sculpted both by jets from the new stars within, and by the intense radiation coming from super star system HD 93129 and its nearby cluster of bright stars, which are a ways up "above" the peaks (and not visible in this image):
image by NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA) (source)
^ The white dashes and arcs coming sideways off the "top" of the peaks in the upper left are caused by jets of material shooting out of the poles of newborn stars at the tips of those peaks as they pull in the material around them (and as that material is driven into them by radiation pressure from the surrounding big stars)--they are "Herbig-Haro" objects, like the ones I showed animations of a week or so ago.
Another neat star-forming region, with gas jetting out from the baby stars forming inside:
Zoomed way in (that's part of the Keyhole Nebula on the left) on a couple of the tiny, really dense gas clouds visible here and there in the main image; they're called by the unflattering name of Bok globules:
image by NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA) (source)
Here we have a pillar of gas and dust sculpted out of and cut off from its main cloud by the intense radiation pressure of the nebula's stars, and, finally getting its due, on the right, hypergiant + supergiant (superhypergiant? hypersupergiant?) binary star HD 93129, with a particularly tiny and eerie Bok globule next to it:
image by NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA) (source)
That's one bandwidth-heavy nebula! ;)
Sat Sep 10, 2011 2:42 am
sunphoenix
Joined: Thu Nov 18, 2010 11:51 am Posts: 82
Hmmm...well ... Selenis will either say screw it and wack him now and eat the clone cost... be damned whatever mother wanted... or she's going to ball his brains out on his office desk... :)
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