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Original author: 
Xeni Jardin

Carolyn Porco, Cassini Imaging Team Leader and CICLOPS director, writes: One of the most gorgeous sights we have been privileged to see at Saturn, as the arrival of spring to the northern hemisphere has peeled away the darkness of winter, has been the enormous swirling vortex capping its north pole and ringed by Saturn's famed hexagonal jet stream.

Today, the Cassini Imaging Team is proud to present to you a set of special views of this phenomenal structure, including a carefully prepared movie showing its circumpolar winds that clock at 330 miles per hour, and false color images that are at once spectacular and informative.

Here are the images, in glorious hi-rez [ciclops.org].    

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The star V838 Monocerotis erupted catastrophically in 2002, growing from obscurity to become one of the brightest known stars in the Milky Way. As the comic strip above shows, it shed a lot of mass during the process. A new model may explain how this happened, if the star was actually part of a binary.

NASA/ESA/The Hubble Heritage Team (STScI/AURA)

Stars are plasma, gas ionized as the result of extreme internal temperatures. A solitary star will be mostly spherical under the force of its own gravity. However, when stars are in close binaries, their mutual attraction distorts their shapes. The extreme version of this is the common envelope stage, wherein the stars' outer regions merge to make a single, huge double star. According to theory, that is. While nobody seriously doubts this model, all the observational evidence for common envelope binaries is indirect.

A new Science paper proposes that a class of violent astronomical events that we've observed may be due to common envelope stars, providing more direct evidence for their existence. These cataclysms are known as "red transient outbursts," and in brightness terms, they're somewhere between novas (flares of nuclear activity at the surfaces of white dwarfs) and supernovas, the violent deaths of stars. N. Ivanova, S. Justham, J. L. Avendado Nandez, and J. C. Lombardi Jr. identified a possible physical model for these outbursts, based on the recombination of electrons and ions in the plasma when the stars' envelopes merge.

The most famous red transient outburst came from the star euphoniously known as V838 Monocerotis. Before 2002, nobody had noticed the star at all, but for a brief period of time, it expanded hugely, flared brightly, and shed an impressive amount of gas and dust into surrounding space. The Hubble Space Telescope (HST) tracked the outburst over the intervening years, but despite the regular check-ins, there is no widely accepted explanation for it.

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Physicist: Not with any current, or remotely feasible technology.  The method in use by the universe today; get several Suns worth of mass into a big pile and wait, is a pretty effective way to create black holes.

In theory, all you need to do to create an artificial black hole (a “black faux”?) is to get a large amount of energy and matter into a very small volume.  The easiest method would probably be to use some kind of massive, super-duper-accelerators.  The problem is that black holes are dense, and the smaller and less massive they are the denser they need to be.

A black hole with the mass of the Earth would be so small you could lose it pretty easy.  Except for all the gravity.

But there are limits to how dense matter can get on its own.  The density of an atomic nucleus, where essentially all of the matter of an atom is concentrated, is about the highest density attainable by matter: about 1018 kg/m3, or about a thousand, million, million times denser than water.  This density is also the approximate density of neutron stars (which are basically giant atomic nuclei).

When a star runs out of fuel and collapses, this is the densest that it can get.  If a star has less than about 3 times as much mass as our Sun, then when it gets to this density it stops, and then hangs out forever.  If a star has more than 3 solar masses, then as it collapses, on it’s way to neutron-star-density, it becomes a black hole (a black hole with more mass needs less density).

The long-winded point is; in order to create a black hole smaller than 3 Suns (which would be what you’re looking for it you want to keep it around), it’s not a question of crushing stuff.  Instead you’d need to use energy, and the easiest way to get a bunch of energy into one place is to use kinetic energy.

There’s some disagreement about the minimum size that a black hole can be.  Without resorting to fairly exotic, “lot’s of extra dimensions” physics, the minimum size should be somewhere around 2\times 10^{-21} grams.  That seems small, but it’s very difficult (probably impossible) to get even that much mass/energy into a small enough region.  A black hole with this mass would be about 10-47 m across, which is way, way, way smaller than a single electron (about 10-15 m).  But unfortunately, a particle can’t be expected to concentrate energy in a region smaller than the particle itself.  So using whatever “ammo” you can get into a particle accelerator, you find that the energy requirements are a little steeper.

To merely say that you’d need to accelerate particles to nearly the speed of light doesn’t convey the stupefying magnitude of the amount of energy you’d need to get a collision capable of creating a black hole.  A pair of protons would need to have a “gamma” (a useful way to talk about ludicrously large speeds) of about 1040, or a pair of lead nuclei would need to have a gamma of about 1037, when they collide in order for a black hole to form.  This corresponds to the total energy of all the mass in a small mountain range.  For comparison, a nuclear weapon only releases the energy of several grams of matter.

CERN, or any other accelerator ever likely to be created, falls short in the sense that a salted slug in the ironman falls short.

There’s nothing else in the universe the behaves like a black hole.  They are deeply weird in a lot of ways.  But, a couple of the properties normally restricted to black holes can be simulated with other things.  There are “artificial black holes” created in laboratories to study Hawking radiation, but you’d never recognize them.  The experimental set up involves tubes of water, or laser beams, and lots of computers.  No gravity, no weird timespace stuff, nothin’.  If you were in the lab, you’d never know that black holes were being studied.

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[Video Link]

Boing Boing reader Cory Poole is a 33-year-old math and science teacher at University Preparatory School in Redding, CA. He sends in this beautiful video of yesterday's annular solar eclipse, and says:

This is a 60 second time-lapse video made from 700 individual frames through a Coronado Solar Max 60 Double Stacked Hydrogen Alpha Solar Telescope. The pictures were shot in Redding, CA, which was directly in the annular eclipse path. The filter on the telescope allows you to see the chromosphere which is a layer that contains solar prominences. The filter only allows light that is created when hydrogen atoms go from the 2nd excited state to the 1st excited state.

 

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The rare transit of Venus across the face of the Sun in 2004 was photographed widely from Europe, to Asia to Africa and North America by professionals and amateurs. North Carolina based photographer David Cortner explains how he made the photograph, which was featured on Astronomy Picture of the Day: “I made this photo on a rainy morning from an overlook above North Carolina’s Catawba River. The sky was clear for only a few minutes, just long enough to grab this photo with a Nikon DSLR and a 5-inch Astro-Physics refractor. I wouldn’t have bothered to get up at all except for the thought that if James Cook would sail halfway around the world to see a transit of Venus, who was I not to at least set up the telescope and hope for the best.”

The next transit of Venus will be in on June 5 or 6, depending on your location. You may want to pencil it in, because the one after June 2012 is not until December 2117. Venus transits come in pairs, eight years apart, then don’t come again for more than 100 years. To see a NASA simulation of the coming transit, click here.

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