Starship Asterisk*

Diana wrote:
Has there been a study to find out what the dark rectangle is? (Just above the center pillar.)

http://en.wikipedia.org/wiki/Bok_globule wrote:
<<Bok globules are dark clouds of dense cosmic dust and gas in which star formation sometimes takes place. Bok globules are found within H II regions, and typically have a mass of about 2 to 50 solar masses contained within a region about a light year or so across. They contain molecular hydrogen (H₂), carbon oxides and helium, and around 1% (by mass) of silicate dust. Bok globules most commonly result in the formation of double or multiple star systems.

Bok globules were first observed by astronomer Bart Bok in the 1940s. In a paper published in 1947, Bok and E.F. Reilly hypothesized that these clouds were 'similar to insect's cocoons' that were undergoing gravitational collapse to form new stars from which stars and star clusters were born. This hypothesis was difficult to verify due to the observational difficulties of establishing what was happening inside a dense dark cloud that obscured all visible light emitted from within it. An analysis of near infrared observations published in 1990 confirmed that stars were being born inside Bok globules. Further observations have revealed that some Bok globules contain embedded warm sources, some contain Herbig-Haro objects, and some show outflows of molecular gas. Millimeter-wave emission line studies have also provided evidence for the infall of material onto an accreting protostar.

Bok globules are still a subject of intense research. Known to be some of the coldest objects in the natural universe, their structure and density remains somewhat a mystery. Methods applied so far have relied on column density derived from near infrared extinction and even star counting in a bid to probe these objects further.>>

Mary Paotullis wrote:
I want to know two things:

Where does the dust come from?

It looks like the creator just spilled their dust jar here and there.

• The Flying Spaghetti Monster is not the neatest creator in the multi-universe:

http://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_formation wrote:

[b][color=#804000][size=180]Those FSM meatballs are actually:[/size] 1) cool oxygen rich red-giant stars & 2) cool carbon-rich giant stars[/color][/b] [b][color=#0000FF]Astronomers know that the dust is formed in the envelopes of late-evolved stars from specific observational signatures. Infrared emission at 9.7 micrometres is a signature of silicate dust in cool evolved oxygen-rich giant stars. Emission at 11.5 micrometres indicates the presence of silicon carbide dust in cool evolved carbon-rich giant stars. These provide evidence that the small silicate particles in space came from the ejected outer envelopes of these stars.[/color][/b]

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<<The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired subsequently during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool oxygen rich red-giant stars and carbon grains condensing in the atmospheres of cool carbon stars. The red-giant stars have evolved off the main sequence and have entered the giant phase of their evolution and are the major source of refractory dust grain cores in galaxies. Those refractory cores are also called Stardust, which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain cores have condensed within expanding interiors of supernovae, a type of cosmic decompression chamber. And meteoriticists that study this refractory stardust extracted from meteorites often call it presolar grains, although the refractory stardust that they study is actually only a small fraction of all presolar dust. Stardust condenses within the stars via considerably different condensation chemistry than that of the bulk of cosmic dust, which accretes cold onto preexisting dust in dark molecular clouds of the galaxy. Those molecular clouds are very cold, typically less than 50K, so that ices of many kinds may accrete onto grains, perhaps to be destroyed later. Finally, when the solar system formed, interstellar dust grains were further modified by chemical reactions within the planetary accretion disk. So the history of the complex grains in the early solar system is complicated and only partially understood.>>

Mary Paotullis wrote:

• how does dust 'boil'?

• Mostly it is really the EGG's that are boiling.

http://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_destruction wrote:
<<How are the interstellar grains destroyed? There are several ultraviolet processes which lead to grain "explosions" for tiny grains. More prominent for interstellar dust grains is sputtering erosion when energetic atoms or ions pierce the surface of a solid to deposit enough energy to cause secondary ions to be ejected from the resulting internal explosion of fast ions. This causes total mass to be sputtered away with a mean lifetime 2-4x10⁸ years.>>

http://en.wikipedia.org/wiki/Evaporating_gaseous_globule wrote:
<<An evaporating gas globule or EGG is a region of hydrogen gas in outer space approximately 100 astronomical units in size, such that gases shaded by it are shielded from ionizing UV rays. Dense areas of gas shielded by an evaporating gas globule can be conducive to the birth of stars. Evaporating gas globules were first conclusively identified via photographs taken by the Hubble Space Telescope in 1995.

EGG's are the likely predecessors of new protostars. Inside an EGG the gas and dust are denser than in the surrounding dust cloud. Gravity pulls the cloud even more tightly together as the EGG continues to draw in material from its surroundings. As the cloud density builds up the globule becomes hotter under the weight of the outer layers, a protostar is formed inside the EGG.

A protostar may have too little mass to become a star. If so it becomes a brown dwarf. If the protostar has sufficient mass, the density reaches a critical level where the temperature exceeds 10 million degrees kelvin at its center. At this point, a nuclear reaction starts converting hydrogen to helium and releasing large amounts of energy. The protostar then becomes a star and joins the main sequence on the HR diagram.>>

neufer wrote:Was this the face that launched a thousand ships,
And burnt the topless towers of Ilium?

jase wrote:This appears to be a double APOD. The same image was awarded an APOD back in 2009 - http://apod.nasa.gov/apod/ap090710.html

Still a fantastic image.

http://www.spitzer.caltech.edu/images/1708-ssc2007-01a-Cosmic-Epic-Unfolds-in-Infrared-The-Eagle-Nebula wrote:

[b][color=#0000FF]Blue is 4.5-micron light[/color]; [color=#00FF00]green is 8-micron light[/color]; and [color=#FF0000]red is 24-micron light[/color].[/b]

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[b][color=#0000FF]Was this the face that launched a thousand ships, And burnt the topless towers of Ilium?[/color][/b]

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<<This majestic view taken by NASA's Spitzer Space Telescope tells an untold story of life and death in the Eagle nebula, an industrious star-making factory located 7,000 light-years away in the Serpens constellation. The image shows the region's entire network of turbulent clouds and newborn stars in infrared light.

The color green denotes cooler towers and fields of dust, including the three famous space pillars, dubbed the "Pillars of Creation," which were photographed by NASA's Hubble Space Telescope in 1995.

But it is the color red that speaks of the drama taking place in this region. Red represents hotter dust thought to have been warmed by the explosion of a massive star about 8,000 to 9,000 years ago. Since light from the Eagle nebula takes 7,000 years to reach us, this "supernova" explosion would have appeared as an oddly bright star in our skies about 1,000 to 2,000 years ago. According to astronomers' estimations, the explosion's blast wave would have spread outward and toppled the three pillars about 6,000 years ago (which means we wouldn't witness the destruction for another 1,000 years or so). The blast wave would have crumbled the mighty towers, exposing newborn stars that were buried inside, and triggering the birth of new ones.

The pillars of the Eagle nebula were originally sculpted by radiation and wind from about 20 or so massive stars hidden from view in the upper left portion of the image. The radiation and wind blew dust away, carving out a hollow cavity (center) and leaving only the densest nuggets of dust and gas (tops of pillars) flanked by columns of lighter dust that lie in shadow (base of pillars). This sculpting process led to the creation of a second generation of stars inside the pillars.

If a star did blow up in this region, it is probably located among the other massive stars in the upper left portion of the image. Its blast wave might have already caused a third generation of stars to spring from the wreckage of the busted pillars.>>

Ann wrote:I like pictures like this one, which shows the overall geometry of the Eagle Nebula. The nebula gets its name from those central pillars whose denser parts resemble an eagle spreading its wings. The Hubble closeup looks nothing like an eagle, of course. My favorite part of the Eagle Nebula is the Fairy, however. And I've just got to show you this piece of space art by Steve Black, where the Fairy is twinned or cloned and turned into a Luminous Flesh Giant - seen better here.

Ann

P.S. Tomorrow's APOD is a spiral hat - any chance it has anything to do with this guy?