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Hubble's deepest view ever unveils earliest galaxies (Ultra-deep field)
SpaceFlight Now ^ | March 9, 2004 | unknown author

Posted on 03/09/2004 11:11:27 AM PST by alnitak

Hubble's deepest view ever unveils earliest galaxies
Posted: March 9, 2004

Astronomers at the Space Telescope Science Institute today unveiled the deepest portrait of the visible universe ever achieved by humankind. Called the Hubble Ultra Deep Field (HUDF), the million-second-long exposure reveals the first galaxies to emerge from the so-called "dark ages," the time shortly after the big bang when the first stars reheated the cold, dark universe. The new image should offer new insights into what types of objects reheated the universe long ago.

This view of nearly 10,000 galaxies is the deepest visible-light image of the cosmos. Called the Hubble Ultra Deep Field, this galaxy-studded view represents a "deep" core sample of the universe, cutting across billions of light-years. Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team
Download a larger image here

This historic new view is actually two separate images taken by Hubble's Advanced Camera for Surveys (ACS) and the Near Infrared Camera and Multi-object Spectrometer (NICMOS). Both images reveal galaxies that are too faint to be seen by ground-based telescopes, or even in Hubble's previous faraway looks, called the Hubble Deep Fields (HDFs), taken in 1995 and 1998.

"Hubble takes us to within a stone's throw of the big bang itself," says Massimo Stiavelli of the Space Telescope Science Institute in Baltimore, Md., and the HUDF project lead. The combination of ACS and NICMOS images will be used to search for galaxies that existed between 400 and 800 million years (corresponding to a redshift range of 7 to 12) after the big bang. A key question for HUDF astronomers is whether the universe appears to be the same at this very early time as it did when the cosmos was between 1 and 2 billion years old.

The HUDF field contains an estimated 10,000 galaxies. In ground-based images, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full Moon) is largely empty. Located in the constellation Fornax, the region is below the constellation Orion.

The final ACS image, assembled by Anton Koekemoer of the Space Telescope Science Institute, is studded with a wide range of galaxies of various sizes, shapes, and colors. In vibrant contrast to the image's rich harvest of classic spiral and elliptical galaxies, there is a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. Their strange shapes are a far cry from the majestic spiral and elliptical galaxies we see today. These oddball galaxies chronicle a period when the universe was more chaotic. Order and structure were just beginning to emerge.

These close-up snapshots of galaxies in the Hubble Ultra Deep Field reveal the drama of galactic life. Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team
Download a larger image here

Installed in 2002 during the last servicing mission to the Hubble telescope, the ACS has twice the field of view and a higher sensitivity than the older workhorse camera, the Wide Field Planetary Camera 2, installed during the 1993 servicing mission. "The large discovery efficiency of the ACS is now being exploited in sky surveys such as the HUDF," Stiavelli says.

The NICMOS sees even farther than the ACS. The NICMOS reveals the farthest galaxies ever seen, because the expanding universe has stretched their light into the near-infrared portion of the spectrum. "The NICMOS provides important additional scientific content to cosmological studies in the HUDF," says Rodger Thompson of the University of Arizona and the NICMOS Principal Investigator. The ACS uncovered galaxies that existed 800 million years after the big bang (at a redshift of 7). But the NICMOS may have spotted galaxies that lived just 400 million years after the birth of the cosmos (at a redshift of 12). Thompson must confirm the NICMOS discovery with follow-up research.

"The images will also help us prepare for the next step from NICMOS on the Hubble telescope to the James Webb Space Telescope (JWST)," Thompson explains. "The NICMOS images reach back to the distance and time that JWST is destined to explore at much greater sensitivity." In addition to distant galaxies, the longer infrared wavelengths are sensitive to galaxies that are intrinsically red, such as elliptical galaxies and galaxies that have red colors due to a high degree of dust absorption.

The entire HUDF also was observed with the advanced camera's "grism" spectrograph, a hybrid prism and diffraction grating. "The grism spectra have already yielded the identification of about a thousand objects. Included among them are some of the intensely faint and red points of light in the ACS image, prime candidates for distant galaxies," says Sangeeta Malhotra of the Space Telescope Science Institute and the Principal Investigator for the Ultra Deep Field's ACS grism follow-up study. "Based on those identifications, some of these objects are among the farthest and youngest galaxies ever seen. The grism spectra also distinguish among other types of very red objects, such as old and dusty red galaxies, quasars, and cool dwarf stars."

Galaxies evolved so quickly in the universe that their most important changes happened within a billion years of the big bang. "Where the HDFs showed galaxies when they were youngsters, the HUDF reveals them as toddlers, enmeshed in a period of rapid developmental changes," Stiavelli says.

Illustration Credit: NASA and A. Feild (STScI)
Download a larger image here

Hubble's ACS allows astronomers to see galaxies two to four times fainter than Hubble could view previously, and is also very sensitive to the near-infrared radiation that allows astronomers to pluck out some of the farthest observable galaxies in the universe. This will hold the record as the deepest-ever view of the universe until ESA, together with NASA, launches the James Webb Space Telescope in 2011.

Though ground-based telescopes have, to date, spied objects that existed just 500 million years after the big bang (at a redshift of 10), they need the help of a rare natural zoom lens in space, called a gravitational lens, to see them. However, the ACS can reveal typical galaxies at these great distances. Even much larger ground-based telescopes with adaptive optics cannot reproduce such a view. The ACS picture required a series of exposures taken over the course of 400 Hubble orbits around Earth. This is such a big chunk of the telescope's annual observing time that Institute Director Steven Beckwith used his own Director's Discretionary Time to provide the needed resources.

The HUDF observations began Sept. 24, 2003 and continued through Jan. 16, 2004. The telescope's ACS camera, the size of a phone booth, captured ancient photons of light that began traversing the universe even before Earth existed. Photons of light from the very faintest objects arrived at a trickle of one photon per minute, compared with millions of photons per minute from nearer galaxies.

Just like the previous HDFs, the new data are expected to galvanize the astronomical community and lead to dozens of research papers that will offer new insights into the birth and evolution of galaxies.

Questions & Answers

1. How faint are the farthest objects?

The Hubble observations detected objects as faint as 30th magnitude. The faintest objects the human eye can see are at sixth magnitude. Ground-based telescopes also can detect 30th-magnitude objects. Those objects, however, are so dim they are lost in the glare of brighter, nearby galaxies.

Searching for the faintest objects in the Ultra Deep Field is like trying to find a firefly on the Moon. Light from the farthest objects reached the Hubble telescope in trickles rather than gushers. The orbiting observatory collected one photon of light per minute from the dimmest objects. Normally, the telescope collects millions of photons per minute from nearby galaxies.

2. How many orbits did it take to make the observations?

It took 400 orbits to make the observations.

3. How many exposures were needed to make the observations?

The Hubble telescope's Advanced Camera for Surveys' wide-field camera snapped 800 exposures, which equals two exposures per orbit. The exposures were taken over four months, from Sept. 24, 2003 to Jan. 16, 2004.

4. How much viewing time was needed to make all the exposures?

The 800 exposures amounted to about 1 million seconds or 11.3 days of viewing time. The average exposure time was 21 minutes.

5. How many galaxies are in the image?

The image yields a rich harvest of about 10,000 galaxies.

6. How many colors (filters) were used to make the observations?

The colors used were blue, green, red, and near-infrared. The observations were taken in visible to near-infrared light.

7. If astronomers made the Hubble Ultra Deep Field observation over the entire sky, how long would it take?

The whole sky contains 12.7 million times more area than the Ultra Deep Field. To observe the entire sky would take almost 1 million years of uninterrupted observing.

8. How wide is the Ultra Deep Field's slice of the heavens?

The Hubble Ultra Deep Field is called a "pencil beam" survey because the observations encompass a narrow, yet "deep" piece of sky. Astronomers compare the Ultra Deep Field view to looking through an eight-foot-long soda straw.

The Ultra Deep Field's patch of sky is so tiny it would fit inside the largest impact basin that makes up the face on the Moon. Astronomers would need about 50 Ultra Deep Fields to cover the entire Moon.

9. How sharp is Hubble's resolution in pinpointing far-flung galaxies in the Ultra Deep Field?

Hubble's keen vision (0.085 arc seconds.) is equivalent to standing at the U.S. Capitol and seeing the date on a quarter a mile away at the Washington monument.

TOPICS: Announcements; Miscellaneous; News/Current Events
KEYWORDS: astronomy; cosmology; galaxies; galaxy; hdf; hubble; hudf; ngst; space
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Highly recommend you follow the links to get the larger images. Makes great wallpaper! ACS is an awesone instrument.
1 posted on 03/09/2004 11:11:28 AM PST by alnitak
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To: alnitak
Awesome. Now to find that pic I saw on TV recently of a Rose Galaxy.
2 posted on 03/09/2004 11:19:31 AM PST by swarthyguy
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To: alnitak
I hope they find my truck keys. . .
3 posted on 03/09/2004 11:20:27 AM PST by jtminton (Brought to you in part by my mother and father.)
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To: alnitak
I'm just to ignorant to understand things. They are looking "back" so far that they are seeing light that hasn't reached us yet.... light from the big bang. So that means that we are moving away from the big bang faster than the light that it caused since we have to look back to see the light from it?
4 posted on 03/09/2004 11:25:42 AM PST by kjam22
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To: swarthyguy
Since they're looking into the past.... maybe they can find an identifable pic of our solar system somewhere in the past.
5 posted on 03/09/2004 11:31:12 AM PST by kjam22
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To: kjam22
Well, obviously we are seeing light that has reached us, otherwise we wouldn't be able to see it. But it has taken N billion years to reach us, so it represents the state of those galaxies N billion years ago, from our perspective. Likewise, we see the sun as it was 8 1/2 minutes ago because it takes light that long to get here.

Maybe you want to try the Cosmology FAQ? This is one of those sites I promise myself I will read one day...

6 posted on 03/09/2004 11:33:38 AM PST by alnitak ("That kid's about as sharp as a pound of wet liver" - Foghorn Leghorn)
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To: alnitak
Think about this, assuming the universe is fairly regular, (and that this view isn't peering into some dense area of the universe and the rest is not nearly as populated), we are looking at one twelve-point-seven millionth of the sky. And we are seeing some 10,000 galaxies (which themselves consist of BILLIONS of stars each). What is 10,000 multiplied by 12.7 million?

The numbers are beyond staggering.

7 posted on 03/09/2004 11:34:38 AM PST by Paradox (In the future, everyone will be Hitler for 15 minutes.)
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To: Paradox
Obviously the light hasn't reached us and that's why they need such a magnifing glass to see it.
8 posted on 03/09/2004 11:35:22 AM PST by kjam22
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To: swarthyguy
Is this the "galaxy" you were talking about? (second picture)
9 posted on 03/09/2004 11:36:28 AM PST by Pyro7480 (Minister for the Conversion of Hardened Sinners,Tomas de Torquemada Gentlemen's Club)
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To: alnitak
I'm interested in what they will find beyond that yellow outer rim of the big bang.
10 posted on 03/09/2004 11:41:21 AM PST by Rennes Templar
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To: alnitak
bump for super coolness.
11 posted on 03/09/2004 11:41:37 AM PST by flashbunny (Taxes are not levied for the benefit of the taxed.)
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To: kjam22
well, the inflation theory of the big bang and the increasing speed of expansion of the universe from dark energy probably would account for us being 'ahead' of this light enough to see it.
12 posted on 03/09/2004 11:44:04 AM PST by Monty22
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To: Monty22
That's what I said.... we have to be moving faster than the light from the big bang for any of what they are saying to be true. So we should be able to look back and see planet earth somewhere in the past. Right?
13 posted on 03/09/2004 11:46:29 AM PST by kjam22
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To: kjam22
I think it's based on the mountain from the old Paul Bunyan/Pecos Bill era stories. The mountain was so tall it took a man 7 days to see it's top, but 7 men could see it in a day. It seems obvious that the more eyes or devices there are to do the looking, the faster you can see something. I would imagine that if we got everyone on Earth to look in the same direction at once, we could see things that haven't even happened yet.

And that's why they won't let me teach science classes.

14 posted on 03/09/2004 11:51:26 AM PST by trebb (Ain't God good . . .)
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To: trebb
:) LOL
15 posted on 03/09/2004 11:52:26 AM PST by kjam22
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To: alnitak
Thanks! Bump

Yahoo! AP link

Hubble Images Show Deepest Universe View Paul Recer/AP

16 posted on 03/09/2004 11:54:44 AM PST by NormsRevenge (Semper Fi Mac ... Support Our Troops! ... Defeat the demRats in November!!! ... Beat BoXer!!!)
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To: Paradox
Did a little math:

Just using this sparse area as a sample, with 10,000 galaxies in it, yields 127,000,000,000,000 galaxies.

There are an estimated 200 Billion stars in our galaxy alone. I guess that's a good average number to use for this.

200 Billion times 127,000,000,000,000 yields 25,400,000,000,000,000,000,000,000 potential stars out there in the sky, and who knows how many planets orbiting them.

Now if John Kerry could just figure out how to tax all of them, there would be no deficit, and everyone in the US could have free health care. Kumbaya.
17 posted on 03/09/2004 11:55:03 AM PST by flashbunny (Taxes are not levied for the benefit of the taxed.)
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To: dubyagee
dark energy probably would account for us being 'ahead' of this light enough to see it.

Gotta love this new term 'dark energy.' I'm seeing it alot now. It is something that we know not what it is, but we give it a name 'dark energy' and attribute actions to it, leading us less than scientific folks into believing that 'dark energy' is something of which we know something about...when the fact is we have no clue what 'dark energy' is or what it does, if it exists or doesn't or what actions to attribute to it if it does. Dark energy, hmmmmm....

18 posted on 03/09/2004 11:56:22 AM PST by dubyagee (Just ranting to no mind.)
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To: kjam22
Actually, the 'cosmology FAQ' is a fantastic resource on this subject, worth the read for sure.
19 posted on 03/09/2004 11:57:27 AM PST by Monty22
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To: alnitak
The universe itself keeps on expanding and expanding
In all of the directions it can whizz.
As fast as it can go, at the speed of light, you know?
Twelve million miles a minute and that's the fastest speed there is.

So remember when you're feeling very small and insecure,
How amazingly unlikely is your birth
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down 'ere on Earth!
20 posted on 03/09/2004 11:58:34 AM PST by mewzilla
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