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Thackeray's Globules: cosmic lumps of butter (2008 Dec 28)

Posted: Sun Dec 28, 2008 6:57 am
by neufer
http://apod.nasa.gov/apod/ap081228.html

<<Explanation: Rich star fields and glowing hydrogen gas silhouette dense, opaque clouds of interstellar gas and dust in this Hubble Space Telescope close-up of IC 2944, a bright star forming region in Centaurus, 5,900 light-years away. The largest of these dark globules, first spotted by South African astronomer A. D. Thackeray in 1950, is likely two separate but overlapping clouds, each more than one light-year wide. Combined the clouds contain material equivalent to about 15 times the mass of the Sun, but will they actually collapse to form massive stars? Along with other data, the sharp Hubble images indicate that Thackeray's globules are fractured and churning as a result of intense ultraviolet radiation from young, hot stars already energizing and heating the bright emission nebula. These and similar dark globules known to be associated with other star forming regions may ultimately be dissipated by their hostile environment -- like cosmic lumps of butter { :D :( }in a hot frying pan.>>
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http://en.wikipedia.org/wiki/William_Ma ... _Thackeray

<<William Makepeace Thackeray (18 July 1811 – 24 December 1863) was an English novelist of the 19th century. He was famous for his satirical works, particularly Vanity Fair, a panoramic portrait of English society. Thackeray, an only child, was born in Calcutta, India, where his father, Richmond Thackeray, held the high rank of secretary to the board of revenue in the British East India Company.>>
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<<The Agnihotra sacrifice in honor of Agni, the Hindu Fire-god.

This oblation consists of throwing BUTTER balls into the fire.
The BUTTER represents the fat victims which were formerly used.
The sacrifice is performed at dawn and sunset (sandhya),
the two crepuscles of the Sun. Agni is identified with
the Sun and, more exactly, with the Fallen Sun
that inflames the earth at the world's end.>>
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. Henry the Fourth, Part One (Folio) 2.4
.
PRINCE HENRY: Didst thou neuer see Titan kisse a dish of BUTTER,
. pittifull hearted Titan that melted at the sweete
. Tale of the Sunne?
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Widenostrils. (French, Bringuenarilles.) A huge giant, who subsisted
on windmills, and lived in the island of Tohu. When Pantagruel and his
fleet reached this island no food could be cooked because Widenostrils
had swallowed "every individual pan, skillet, kettle, frying-pan,
dripping-pan, boiler, and saucepan in the land," and died from
eating a lump of BUTTER.

Tohu & Bohu, two contiguous islands (in Hebrew, toil & confusion),
mean lands laid waste by war. The giant had eaten everything,
so that there was "nothing to fry with," as the French say.
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<<The Hatter was the first to break the silence. 'What day
of the month is it?' he said, turning to Alice: he had taken
his watch out of his pocket, and was looking at it uneasily,
.
Shaking it every now and then, and holding it to his ear.
Alice considered a a little, and then said 'The FOURTH.'
.
. 'Two days wrong!' sighed the Hatter.
.'I told you BUTTER wouldn't suit the works!'
. he added looking angrily at the March Hare.
'It was the best BUTTER,' the March Hare meekly replied.>>
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Re: Thackeray's cosmic lumps of butter (APOD 2008 December 2

Posted: Mon Dec 29, 2008 4:13 am
by neufer
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Thackeray's Globules in IC 2944
http://www.spaceref.com/news/viewpr.html?pid=7022

PRESS RELEASE
Date Released: Thursday, January 3, 2002
Source: Space Telescope Science Institute

<<Strangely glowing dark clouds float serenely in this remarkable and beautiful image taken with NASA's Hubble Space Telescope. These dense, opaque dust clouds - known as "globules" - are silhouetted against nearby bright stars in the busy star-forming region, IC 2944. These globules were first found in IC 2944 by astronomer A.D. Thackeray in 1950.

Although globules like these have been known since Dutch-American astronomer Bart Bok first drew attention to such objects in 1947, little is still known about their origin and nature, except that they are generally associated with large hydrogen-emitting star-formation regions, called "HII regions" due to their glowing light of hydrogen gas.

The largest of the globules in this image is actually two separate clouds that gently overlap along our line of sight. Each cloud is nearly 1.4 light-years (50 arcseconds) along its longest dimension, and collectively, they contain enough material to equal over 15 solar masses. IC 2944, the surrounding HII region, is filled with gas and dust that is illuminated and heated by a loose cluster of O-type stars. These stars are much hotter and much more massive than our Sun. IC 2944 is relatively close by, located only 5900 light-years (1800 parsecs) away in the constellation Centaurus.

Thanks to the remarkable resolution offered by the Hubble Space Telescope, astronomers can for the first time study the intricate structure of these globules. The globules appear to be heavily fractured, as if major forces were tearing them apart. When radio astronomers observed the faint hiss of molecules within the globules, they realized that the globules are actually in constant, churning motion, moving supersonically among each other. This may be caused by the powerful ultraviolet radiation from the luminous, massive stars, which also heat up the gas in the HII region, causing it to expand and stream against the globules, leading to their destruction. Despite their serene appearance, the globules may actually be likened to clumps of butter put onto a red-hot pan.

It is likely that the globules are dense clumps of gas and dust that existed before the massive O-stars were born. But once these luminous stars began to irradiate and destroy their surroundings, the clumps became visible when their less dense surroundings were eroded away, thus exposing them to the full brunt of the ultraviolet radiation and the expanding HII region. The new images catch a glimpse of the process of destruction. Had the appearance of the luminous O-stars been a bit delayed, it is likely that the clumps would actually have collapsed to form several more low-mass stars like the Sun. Instead they are now being toasted and torn apart.>>
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http://adsabs.harvard.edu/abs/1997A&A...327.1185R

<<We have studied the complex of small globules discovered by A.D. Thackeray in the southern HII region IC 2944. They are located precisely on the line-of-sight to the luminous OB stars in the region, and thus appear as shadows against the bright HII region. Thanks to this geometry, exceptionally fine details can be discerned on CCD images, which show that the globules are generally sharp-edged and highly structured, and that the complex contains a multitude of fragments in all sizes down to the resolution element of about one arcsec (1800 AU). CO millimeter observations reveal that the largest globule consists of two kinematically separate entities, with masses of about 11 and 4 M_sun. Very large velocity differences exist between the various globules, suggesting that the globules comprise a highly dynamic system perhaps one million years old. We believe that the globules are the remnants of an elephant-trunk observed from behind, originating as a Rayleigh-Taylor instability in an expanding neutral shell powered by the hot HII region. The globule complex is now in an advanced stage of disintegration. We have found no evidence for star formation in any of the globules.>>
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Re: Thackeray's cosmic lumps of butter (APOD 2008 December 2

Posted: Mon Dec 29, 2008 5:43 pm
by BMAONE23
Is that Thackeray's wife and dog in the upper right corner waving good bye???

a couple of small globules at night

Posted: Mon Dec 29, 2008 10:37 pm
by neufer
BMAONE23 wrote:Is that Thackeray's wife and dog in the upper right corner waving good bye???
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. _Roundabout Papers_ by William Makepeace Thackeray
_______ 8: De Juventute
.
<<At the pastry-cook's we may have over-eaten ourselves (I have admitted half a crown's worth for my own part, but I don't like to mention the REAL figure for fear of perverting the present generation of boys by my monstrous confession)--we may have eaten too much, I say. We did; but what then? The school apothecary was sent for: a couple of small globules at night, a trifling preparation of senna in the morning, and we had not to go to school, so that the draught was an actual pleasure.>>
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THACKERAY'S GLOBULES

Posted: Wed Dec 31, 2008 2:04 am
by serge
On december 28 th, the picture of the day was Thackeray's Globules. To me it's a Bok Globules , my question is: Is there a distinction between a Bok Globules and a Thackeray's Globules or is it the same object. If so , why not call it simply a Bok Globules ? If it bears the name of Thackeray because he discover that specific Globules , why not calling it a Bok's Globules named Thackeray in his honnor. As an example If I discover an asteroide , it will still be called an asteroid but it will bear a number and my name , it will not be redefined as a John Doe Object is in it ? If someone knows the answer , I'll appreciate. Regards :D

Re: THACKERAY'S GLOBULES

Posted: Wed Dec 31, 2008 3:57 am
by bystander
serge wrote:On december 28 th, the picture of the day was Thackeray's Globules. To me it's a Bok Globules , my question is: Is there a distinction between a Bok Globules and a Thackeray's Globules or is it the same object. If so , why not call it simply a Bok Globules ? If it bears the name of Thackeray because he discover that specific Globules , why not calling it a Bok's Globules named Thackeray in his honnor. As an example If I discover an asteroide , it will still be called an asteroid but it will bear a number and my name , it will not be redefined as a John Doe Object is in it ? If someone knows the answer , I'll appreciate. Regards :D
Thackeray's Globules are Bok globules specific to IC 2944, discovered in 1950 by A.D. Thackeray.