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Transcript
T h r o u g h H u b b l e ’s E ye : : b y M a t t h e w S h i n d e l l
A STELLAR NURSERY IN THE TRIFID NEBULA IS
TORN APART BY RADIATION FROM A NEARBY,
MASSIVE STAR. THE HUBBLE SPACE TELESCOPE
IMAGE ALSO PROVIDES A PEEK AT EMBRYONIC
STARS FORMING WITHIN AN ILL-FATED CLOUD
OF DUST AND GAS. THE HUGE CLOUD IS DESTINED
TO BE EATEN AWAY BY THE GLARE FROM THE
MASSIVE NEIGHBOR. ASU ASTRONOMER JEFF
HESTER SAYS THAT SUCH STELLAR ACTIVITY
IS A BEAUTIFUL EXAMPLE OF HOW THE LIFE
CYCLE OF A STAR LIKE OUR SUN IS INTIMATELY
CONNECTED WITH ITS MORE POWERFUL SIBLINGS.
Snap! Colorful close-ups of a pulsar. Snap! Images of a nebula worthy of framing at poster size.
Snap, snap! Baby pictures of galaxies. The orbiting Hubble Space Telescope and other marvels
of science and technology provide new spectacular images of the universe on a regular basis.
Modern humans take these breathtaking images for granted. But it was not always that way.
Four hundred years ago, human beings had no real
concept of a universe beyond the Earth, at all. In the human mind,
Earth existed at the center of a very compact universe that was
dominated by Earth itself.
Four hundred years ago the camera had not been invented, nor
had the telescope. For sky watchers, the naked eye was about as good as
it got. Forget snapshots or even close-ups of objects in the heavens;
there was no way to get a good look at all, much less a close-up look.
Galaxies and pulsars and other celestial objects were beyond human
comprehension. They were not even in the vocabulary. As for the age
of the universe, that remained a question science could not answer.
Things changed. In 1609, the Italian astronomer Galileo Galilei
designed a telescope that could magnify distant objects and make them
appear up to 20 times closer. With his telescope in hand, Galileo
revolutionized astronomy. He looked at the moon, watched the
phases of planets like Mars and Venus, discovered the four satellites
of Jupiter, and was the first to see sunspots. His observations
of the motions of the planets added strong evidence to the model
of a sun-centered solar system put forth years earlier by Polish
astronomer Nicolaus Copernicus.
Still, one thing kept Galileo’s telescope — and even the stronger,
more powerful telescopes that followed — from seeing the universe
clearly. The atmosphere—the very thing that made the observer’s life
livable—got in the way of his understanding. And no ultraviolet light
could be seen through the atmosphere. Everything remained in a haze.
In 1990, the haze lifted. A universe that had grown considerably
since the days of Galileo suddenly came into focus.
“Putting the Hubble Space Telescope (HST) in orbit and getting it to
work properly,” says ASU astronomer Rogier Windhorst, “was one of
the grand opening battles for modern astronomy.” Windhorst should
know—he and fellow ASU astronomer Jeff Hester have been working
with Hubble since its rocky beginning. They and their colleagues have
helped scientific understanding of the universe take as big a step forward as that moment Galileo pointed his telescope toward the sky.
The HST is more than halfway through its mission. By 2008 or
earlier, the world’s first orbiting telescope may cease to function. When
this happens, HST will leave the sky in the capable hands of newer,
more technologically sophisticated instruments—some of which have
already taken their posts. But until it takes its last image, Hubble will
remain the only space telescope capable of looking at the sky in visible
light. It’s not nearly ready to be retired as a historical landmark.
Hester and Windhorst continue to push the telescope to its limits.
They work in collaboration with others of NASA’s array of orbiting
instruments such as the Chandra X-Ray Observatory. They also work
with observatories on the ground like the Vatican Advanced Telescope
on Mount Graham and the National Radio Astronomy Observatory’s
Very Large Array Radio Telescope on the desert plains of San Agustin,
New Mexico.
The results of work by Hester and Windhorst are images that are
both beautiful and revealing.
EAGLE NEBULA: A PLACE OF STELLAR BIRTH
Jeff Hester readily admits that he likes to take pretty pictures, but not
without a scientific purpose. “What exactly does it mean to be
beautiful?” asks Hester. “Human beings get by in the world by being
able to recognize and relate to patterns. That’s what we do. That’s where
our idea of beauty comes from. It is also where science comes from.”
The image of the Eagle Nebula is evidence of what Hester is talking
about. A pattern emerges and the picture becomes all the more beautiful.
Hester and his colleagues know that young and forming stars are
contained within the smoky columns of the Eagle. They learn from
both infrared and radio telescope observations. Add that information
to what they see in the Hubble image, and they can piece together
the story of how these stars are being formed.
The ASU scientist says that the stars seen outside of the columns
in the Hubble image are massive—10 to 40 times the mass of the sun.
These stars are also as much as 100,000 times more luminous. The
stars are so hot and so radiant that they give off incredible amounts
of ultraviolet light. They dump excess energy into their surroundings.
The energy heats and ionizes the gas around them. “It’s a little like
turning a blowtorch on a block of dry ice,” says Hester. “When these
stars turn on, they immediately start reshaping their environment.”
The columns of the Eagle Nebula are in fact being pushed away
by this blast of energy, what scientists call an “ionization front.”
WINTER 2004 ASU RESEARCH
22 | 23
EERIE, DRAMATIC PICTURES FROM THE HUBBLE SPACE TELESCOPE
SHOW NEWBORN STARS EMERGING FROM "EGGS." NOT THE
BARNYARD VARIETY, BUT RATHER DENSE, COMPACT POCKETS OF
INTERSTELLAR GAS CALLED EVAPORATING GASEOUS GLOBULES (EGGS).
HUBBLE FOUND THE "EGGS," APPROPRIATELY ENOUGH, IN THE
EAGLE NEBULA, A NEARBY STAR-FORMING REGION
6,500 LIGHT-YEARS AWAY IN THE CONSTELLATION SERPENS.
EEGS ARE SEEN AT THE TIP OF A PILLAR 6 TRILLION MILES HIGH.
“Human beings get by
in the world by being able
to recognize and relate to patterns.
That’s what we do.That’s where
our idea of beauty comes from.
It is also where science comes from.”
Jeff Hester
“These things are spires left behind after the stuff around them has been
eroded away by radiation,” Hester explains. “The surface is being heated
by that radiation. The high pressure then drives off the material.”
The material inside the column is being compressed. The compression
triggers the formation of new stars. The column is then eaten away
and the new stars revealed through the same process. Hester and his
colleagues now believe that nebulae like the Eagle are where most new
stars are formed. It was likely in a place like this where our own sun and
solar system were born.
CRAB NEBULA: A PLACE OF STELLAR DEATH
Not all nebulae contain young and forming stars. Some, like the Crab
Nebula, are the results of stellar deaths.
The Crab is 7,000 light-years from Earth. That’s no small distance,
considering that a light-year (the amount of distance light travels in
one year) is 5,865,696,000,000 miles! Still, 7,000 years after the star that
formed the Crab exploded, the light it produced was observable on Earth
with the naked eye. Chinese astronomers observed the explosion in 1054.
Cave paintings in the Southwest United States suggest that Native people
also witnessed and recorded the event. Today, scientists see the remnants
of that explosion when they look at a picture of the Crab Nebula.
Hester took a new look at the Crab. He combined frames of images of
the Crab taken with HST with frames taken at the same times by scientists
using the orbiting Chandra X-ray Observatory. The result is a time-lapse
movie that reveals some unbelievable features never seen in still images.
A spinning neutron star is at the center of the Crab Nebula. Astronomers
call these spinning stars “pulsars.” The neutron star is the result of a massive
stellar implosion. The implosion was so powerful that electrons and protons
collapsed into one another and were forced to combine.
The neutron star itself is smaller than the city of Phoenix. It has a radius
of about 15 to 20 kilometers. Still, it packs a wallop. The star’s mass is almost
twice that of the sun. It has a density of almost 1 billion tons per teaspoon.
Its magnetic field is 2 trillion times stronger than that of the Earth. This is
not a static entity. The pulsar spins at a rate of 30 revolutions every second.
“The conditions surrounding the neutron star are not what you
encounter in everyday life,” Hester says. “The magnetic field is incredibly
powerful.” The conditions are similar to what occurs inside particle accelerators, the giant machines that physicists use to smash atoms. Physicists use
the massive machines to hurl atoms and pieces of atoms into one another at
incredible speeds. The scientists then study the forces involved as well as the
remains of the atomic head-on collisions.
Hester says the conditions at a neutron star are just as extreme. “There
are some really incredible quantum physics going on in here.”
Photons of light are essentially pure energy. The photons surrounding
the pulsar are so energetic that when they collide they can form pairs of
matter and antimatter electrons. It’s as strange as science fiction, but the
story has only just begun. “Imagine a rope with a length equivalent to the
radius of the moon,” Hester explains. “The rope is whipping around 30
times per second with a bucket on the end. At that speed, the bucket would
be moving at near the speed of light.”
When such speeds and forces are involved, something has to give.
Objects cannot travel faster than the speed of light. The imaginary bucket
—a mixture of matter and antimatter—is f lung out into space. It slams into
its surroundings and starts emitting what the atom-smashing physicists
described earlier call “synchrotron radiation.”
The Crab Nebula looks like a top on its side when researchers study the
composite images. The body and spindle of the top are formed by the wind
and jets coming out of the pulsar. The Hubble and Chandra movies show this
matter and antimatter streaming from the pulsar at half the speed of light.
UNIVERSE OF A DIFFERENT COLOR
Rogier Windhorst has taken his share of pretty pictures. Many of his best are
done in ultraviolet (UV) light, a form of energy invisible to the human eye.
The Earth’s atmosphere absorbs most of the UV light from outer space.
The ASU astronomer has found that what you see when you look at a galaxy
often depends on the wavelength of light in which you view that galaxy.
What’s wrong with visible light? Why would anyone want to look at
galaxies in the invisible wavelengths of UV? To answer, Windhorst describes
the first image ever taken with the fixed HST. “We saw all these beautiful
galaxies,” says Windhorst. “But not all of them were normal galaxies;
the elliptical and spirals and egg-shaped galaxies we were used to seeing
through telescopes. The really far-away galaxies are these amazing globs,
tadpoles, and train wrecks. They are all unusual in some way. It’s just
amazing how different they are.”
THIS CRAB NEBULA IMAGE WAS CREATED FROM SUPERIMPOSED HUBBLE SPACE TELESCOPE IVISIBLE LIGHT IMAGES (RED) AND CHANDRA X-RAY DATA (BLUE).
THE INTENSE ELECTROMAGNETIC RADATION FROM THE CENTRAL STAR ACCELERATES ELECTRONS IN THE SURROUNDING GAS. HIGH ENERGY ELECTONS EMIT X-RAYS.
THE SIZE OF THE X-RAY IMAGE IS SMALLER BECAUSE THE HIGH ENERGY ELECTRONS RADIATE AWAY THEIR ENERGY MORE QUICKLY THAN THE LOWER ENERGY
OPTICALLY EMITTING ELECTRONS. THE INNER RING IS ABOUT ONE LIGHT YEAR ACROSS.
WINTER 2004 ASU RESEARCH
24 | 25
DO FARAWAY GALAXIES LOOK WEIRD BECAUSE THEY ARE TRULY WEIRD?
OR ARE THEY NORMAL GALAXIES THAT LOOK ODD BECAUSE ASTRONOMERS
GET AN INCOMPLETE PICTURE, SEEING ONLY THE BRIGHTEST PIECES?
WINDHORST AND COLLEGUES STUDIED 37 NEARBY GALAXIES TO FIND OUT.
THEY COMPARED SHAPES SEEN IN ULTRAVIOLET LIGHT WITH THOSE OF DISTANT
GALAXIES. FROM THESE HUBBLE ULTRAVIOLET IMAGES THEY LEARNED NOT ALL
THE FARAWAY GALAXIES NECESSARILY POSSESS INTRINSICALLY ODD SHAPES.
RIGHT: THE CENTRAL REGION OF SPIRAL GALAXY
NGC 3310 SHOWS EVENLY
DISTRIBUTED YOUNG AND OLD STARS. IF THIS WERE TRUE FOR MOST GALAXIES,
ASTRONOMERS WOULD BE ABLE TO RECOGNIZE FARAWAY GALAXIES FAIRLY EASILY.
IN MOST GALAXIES STARS ARE SEGREGATED BY AGE, MAKING CLASSIFICATION
MORE DIFFICULT. NGC 3310 IS 46 MILLION LIGHT-YEARS FROM EARTH
IN THE CONSTELLATION URSA MAJOR.
FAR RIGHT: A COSMIC COLLISION BETWEEN GALAXIES UGC 06471 AND
UGC 06472. THESE COLLISIONS OCCURRED FREQUENTLY IN THE EARLY UNIVERSE,
PRODUCING GALAXIES OF UNUSUAL SHAPES. THE COLLISON OCCURRED ABOUT
145 MILLION LIGHT-YEARS FROM EARTH IN THE CONSTELLATION URSA MAJOR.
“Hubble is uniquely suited
to study sub-galactic objects
at these great distances.”
These abnormal galaxies turned out to be incredibly common. In 1995,
after 14 straight days of focused HST observation, the scientists produced
the Hubble Deep Field image. The image was filled with irregular galaxies,
showing just how common they were in the universe. Windhorst and his
colleagues realized that things probably weren’t exactly as they seemed.
Very little of the light that reaches the Earth from space starts out
in the same wavelength as it is received.
The light is redshifted — “stretched” by the expansion of the universe,
he explains. The starlight we see, for example, starts out primarily as ultraviolet light and then is redshifted to visible light on the long journey to
Earth. The irregular galaxies are incredible distances from Earth, typically,
from 5 to 12 billion light-years away. But it was clear to the astronomers that
the faint wavelengths they emitted were actually redshifted ultraviolet light.
The ASU scientist says that ultraviolet light emitted from regions within
a galaxy where hot, young stars reside is likely the only light that reaches
Earth. However, that light is the only piece of the puzzle available for those
observing such galaxies. The other pieces exist; they just aren’t visible to us.
Windhorst and his colleagues decided to look at nearby galaxies in
the ultraviolet. They settled on 37 nearby galaxies, normal spirals and
ellipses that could be compared to the irregular galaxies. The resulting
images are ghostly blue, but beautiful nonetheless. They reveal that the faraway galaxies are not that weird after all.
Windhorst explains that a normal spiral galaxy with a pinwheel shape
has a strikingly different profile when seen in ultraviolet. In visible light,
spiral arms radiate out from a dense bar of old stars at the center. However,
when seen in ultraviolet, the view can be completely transformed.
Astronomers see a ring of hot young stars around the galaxy’s center.
The findings by the ASU scientist support the idea that astronomers are
detecting the “tip of the iceberg” when observing very distant galaxies.
The irregular galaxies in the Deep Field are the youngest currently
observable galaxies in the universe.
Rogier Windhorst
DARK AGES: LIFTING THE VEIL OF THE BEGINNING
Astronomers cannot see the very edge of the universe. Not yet. What light
may exist there is so young that it comes from a time when the universe was
not much more than a warm bath of neutral hydrogen gas. The first few stars
and galaxies formed in this period are concealed from us today by this gas.
The stars and galaxies we do see are visible because the gas between them
and us has been ionized by electromagnetic radiation—light.
On this front, Windhorst and graduate student Haojing Yan are pushing
HST to its limits. They have found several faint objects on the very edge of
the observable. At a redshift of 6, these objects are 13 billion light-years
away from the Earth. They come from the period when galaxies and stars
were produced in numbers massive enough to ionize the universe. It is
a period astronomers have termed the end of the universe’s “Dark Ages.”
According to Windhorst, when the light did come and ionize the
universe, the dwarf galaxies he and Yan identified started shining in
significant numbers. “Somebody turned on the lights and there it was,
the end of the Dark Ages,” he says.
To see these young, star-forming clumps at the edge of the observable,
Windhorst and Yan first had to do a little clean-up work. Pesky brown
dwarf stars in the foreground of our own galaxy were blocking their view.
“They are like drops on a windshield when viewing the lights of a distant
city from your car at night,” Windhorst says.
At the bottom of the star sequence, brown dwarfs are stars that never
made it. Their mass is less than a tenth that of the sun. They weigh a bit
more than the planet Jupiter. “Brown dwarf stars are basically balls of gas
that didn’t have enough gravity to ignite their own nuclear fusion,”
Windhorst explains. “They never started shining. They just sat there,
waiting for nothing to happen.”
Unable to literally wipe the brown stars away, Windhorst and Yan
used a series of HST’s filters to identify and remove the brown dwarfs.
This gave the two ASU researchers, and science, the clearest view yet
of the end of the Dark Ages.
Lights, camera, action!
ASTRONOMY RESEARCH AT ASU IS SUPPORTED BY THE NASA HUBBLE SPACE TELESCOPE PROJECT, THE NASA JAMES WEBB TELESCOPE PROJECT, AND THE NASA CHANDRA X-RAY OBSERVATORY. FOR MORE INFORMATION,
CONTACT
J. JEFFREY HESTER, PH.D., OR ROGIER A. WINDHORST, PH.D., DEPARTMENT OF PHYSICS AND ASTRONOMY, 480.965.3561. SEND E-MAIL TO: [email protected] OR TO: [email protected]
TO VIEW SPECTACULAR HST IMAGES, VISIT THE SPACE TELESCOPE SCIENCE INSTITUTE AT: HTTP://HUBBLE.STSCI.EDU/GALLERY/
Perspective can make all the difference.
Some people look up at the night sky and see a random
sprinkling of stars. Others see bears and hunters, crabs and
scorpions, the connect-the-dot images of constellations.
When Dan Matlaga reads Moby Dick, he also sees
constellations. In lines and paragraphs that have stumped
literary critics for years, Matlaga has found stars and
planets, galaxies and moons. "Once you factor the sky
into the novel, the story completely opens up," says
Matlaga, ASU's planetarium coordinator.
More than 150 years after Herman Melville's best-known
work was published, Matlaga is finding astronomical
references in the book that no critic has ever noticed.
Perhaps this is because most literary critics do not
approach life with an astronomical perspective.
The definitive edition of Moby Dick includes many pages
listing problems and inconsistencies critics have found
within the novel. Many critics claim that Melville was
careless about detail.
"Actually, he was obsessed with detail," Matlaga says.
Matlaga believes that many of these "problems" were,
in fact, intentional. Readers have simply missed their
meaning. Matlaga presented his discoveries at Oxford
University in August, 2003 at the "Inspiration of
Astronomical Phenomena" conference.
One example is a sailor named Bulkington, who appears
briefly in the beginning of the book, then disappears
suddenly without explanation.
Bulkington first appears in Chapter 3, "The Spouter-Inn."
The crew of the Pequod is carousing at the inn, but
Bulkington remains aloof and apart from the crowd.
At some point during the evening, Bulkington slips away
unnoticed. When the other sailors realize he is gone, they
dart off to find him, calling, "Bulkington! Bulkington!
Where's Bulkington?"
Bulkington reappears later in the brief chapter
"The Lee Shore." Here, he is at the helm of the Pequod.
Later on, Ahab takes the helm and Bulkington disappears.
Critics have long assumed that Bulkington is an
irrelevant remnant from an earlier version of the story.
Looking skyward, Matlaga finds a different explanation.
"It turns out that Bulkington is the North Star. 'The Lee
Shore' is Melville as a sailor paying homage to the North
Star. It is magnificent prose to the North star," he says.
The North Star is critical to navigation, so the sailors
are understandably distressed by Bulkington's absence
at the inn. Later, Bulkington disappears from the novel
because the Pequod crosses the equator. The North Star
is visible only from the northern hemisphere. "[Melville] is
giving us clues that they're traveling south. If you map out
the ship's progress, as soon as the ship crosses the equator,
Ahab takes over the tiller," says Matlaga.
Matlaga has, in fact, mapped out the ship's progress,
using astronomical references embedded in the text.
Interpreting these references has allowed him to determine
the precise dates and locations of almost every event in
the book. According to Matlaga, there is no way that
all of the variables could line up to provide such precise
information coincidentally. In addition, many of the
important dates in the novel correspond with events
in Melville's own life.
"Before my work, scholars weren't sure what year
the action in the novel took place," says Matlaga.
"Now that I've factored in the sky, I can tell you that
Ahab loses his life on January 4, 1840. I can tell you
Captain Ahab was born in the same year as Melville's
father. Dust off the Carl Jung, we're talking about
Herman Melville here!" Diane Boudreau
BACKGROUND:
A TINY, YOUTHFUL SPIRAL GALAXY,
ESO 418-008
REPRESENTS THE MYRIAD OF DWARF GALAXIES SEEN IN DEEP SURVEYS.
THESE GALAXIES ARE MUCH SMALLER THAN OUR MILKY WAY, AND THE IMAGE
SHOWS A POPULATION OF STARS MORE STRONGLY SEGREGATED BY AGE.
OLDER STARS [RED] OCCUR IN THE CENTER AND YOUNGER [BLUE]
IN THE DEVELOPING SPIRAL ARMS. THESE SMALL, YOUNG GALAXIES MAY BE
THE BUILDING BLOCKS OF GALAXY FORMATION. ESO 418-008 IS LOCATED
56 MILLION LIGHT-YEARS FROM EARTH IN THE CONSTELLATION FORNAX.
WINTER 2004 ASU RESEARCH
26 | 27
r e d
S CIENTISTS
KNOW THAT LIGHT TRAVELS AS WAVE PACKETS
OF VIBRATING ELECTROMAGNETIC ENERGY.
T HE
PACKETS
ARE THE QUANTUM PARTICLES OF LIGHT, CALLED PHOTONS .
A
PHOTON ’ S RATE OF VIBRATION , CALLED FREQUENCY,
CORRESPONDS TO WAVELENGTH AND COLOR .
WE
PERCIEVE
HIGHER FREQUENCY, SHORTER ELECTROMAGNETIC WAVES
AS BLUE , AND LOWER FREQUENCY, LONGER WAVES AS RED .
L IGHT
APPEARS STRETCHED TO LONGER WAVELENGTHS
BY A SOURCE THAT IS MOVING AWAY FROM US .
S OUND
WAVES ALSO SHOW THIS EFFECT. A PERSON STANDING
BESIDE A ROAD HEARS THE DROP IN FREQUENCY, OR PITCH ,
b l u e
OF THE SOUND CAUSED BY A PASSING CAR .
S UPERHEATED
ATOMS OF STELLAR ATMOSPHERES EMIT
LIGHT IN CHARACTERISTIC FREQUENCY PATTERNS .
A STRONOMERS USE SPECTROSCOPES TO DETECT THESE
PATTERNS , A KIND OF “ FINGERPRINT ” OF AN ATOM .
T HEY MATCH THE LIGHT FROM MOVING STARS TO
ATOMIC SPECTRA MADE IN STATIONARY LABORATORIES .
T HE
DIFFERENCE , CALLED REDSHIFT OR BLUESHIFT, REVEALS
THE VELOCITY OF DISTANT STARS AND GALAXIES .
DISTANT GALAXIES ARE REDSHIFTED .
T HEY
A LL
THE
ARE MOVING
AWAY FROM US , AND THOSE FURTHEST MOVE THE FASTEST.
A STRONOMERS
CONSIDER THIS IMPORTANT OBSERVATION
DIRECT EVIDENCE THAT THE UNIVERSE IS EXPANDING .
A FEW OF THE 18 SMALL BLUE OBJECTS IMAGED BY WINDHORST AND HIS TEAM. EACH CLUMP
CONTAINS SEVERAL BILLION STARS WHICH COULD BE THE SEEDS OF SOME OF TODAY'S GALAXIES.
EACH OBJECT IS 2,000 TO 3,000
LIGHT-YEARS ACROSS,
11 BILLION LIGHT-YEARS
FROM EARTH.
18 easy pieces –and counting
Rogier Windhorst was an active radio astronomer when the f lawed
Hubble Space Telescope (HST) was put into Earth orbit in 1990. Working
with ground-based radio telescopes such as the Westerbork Synthesis
Radio Telescope in The Netherlands, the Very Large Array in New Mexico,
the Palomar 200-inch telescope in California, and the Multiple Mirror
Telescope on Arizona’s Mt. Hopkins, the ASU astronomer already had
several galaxy discoveries under his belt.
When scientists heard that the HST was f lawed, they became wary
of using it. Hubble data was not in as high demand as had been expected.
Windhorst took this opportunity to jump to the front of the line. “I was
sort of a guinea pig to see if you could do good science with a f lawed
telescope,” Windhorst says.
Windhorst did just that. He targeted a galaxy with a redshift of 2.4—
11 billion light-years from Earth—and used the HST to study it at higher
resolution. His experience with radio astronomy techniques came in
handy, and allowed him to sharpen f lawed images by using computer
algorithms. Here he saw the first visible-light images of his galaxy,
in blurred but bearable focus.
In 1994, Windhorst was offered the opportunity to take images with
the repaired HST. With the corrected telescope, he could look even further
out, where the light was older—deeper into the universe’s past. Using
more filters to look at the same area as before, he made an unexpected
discovery. “That was a real boon, because we discovered something
absolutely amazing,” Windhorst recalls. “I’d been studying this area of
space since 1988. Now I was seeing 18 objects completely unknown to me.”
The discovery was difficult to explain at first. It remained difficult until
Windhorst and his colleagues realized that looking through the Hubble
was like looking through a long straw. The distance between the telescope
and the objects it observes may be great, but the angular distance between
the objects it observes remains the same. It is no greater than the distance
between our Milky Way Galaxy and the Andromeda Galaxy—
our nearest neighbor at a distance of a mere 2 million light years.
Once they realized the amount of space involved, Windhorst and
his colleagues had their explanation. What they were seeing were
the building blocks of galaxies. “These pictures were showing us how
galaxies form,” he explains. “They showed us that smaller clumps—
sub-galactic clumps—merge over the course of time. They move around.
Smaller ones get caught in the gravity of larger ones. The big guys gobble
up the little ones. Kind of like corporate mergers on Wall Street.”
Since finding sub-galactic clumps at a redshift of 2.4, Windhorst
has gone back and found even smaller pieces at redshift of 6. That is
nearly 13 billion light-years from Earth. He has chased young and forming
galaxies back to the edge of the observable universe—the end of what
astronomers refer to as the “Dark Ages” of the universe.
But, like the young galaxies from Windhorst’s other work, these
objects are just the beginning of what is sure to be a wealth of future
discovery. “If we could go another hundred or thousand times fainter,
we would see perhaps tens of thousands of clumps that happened even
earlier than the first 900 million years,” he says. “We might see light
from 500 million or 300 million years after the Big Bang. And that
would be like observing the very first stars, or seeing the beginning
of the end of the ‘Dark Ages.’”
To see these objects, the ASU astronomer says that much more sensitive
detectors are necessary. For this reason, Windhorst is involved in planning
NASA’s “Next Generation Space Telescope,” the James Webb Space
Telescope (JWST).
The JWST will be physically larger than the Hubble. It will have
a deployable mirror 6.5 meters in diameter that is made of hexagonal
segments. NASA plans to place the JWST far out in a point past the orbit
of our moon. This will get it away from the “background noise” of
the Earth. Currently scheduled for launch in 2011, the JWST will also
be fine-tuned to do infrared observations work. Scientists will use it
to search for the earliest stars of the universe.
“If there is first light out there, this telescope will see it,” Windhorst says.
“We will then know how the first stars started shining.” Matthew Shindell
R OGIER W INDHORST AND J EFF H ESTER UNDER THE DOME
ASU P LANETARIUM . P ROJECTED ABOVE , THE
H UBBLE D EEP F IELD IMAGE REVEALS LITERALLY THOUSANDS
OF DISTANT GALAXIES FOUND IN A TINY SLICE OF THE SKY.
OF THE
First light–twice
ASU astronomer Jeff Hester’s scientific career has followed many
of the same ups and downs as the Hubble Space Telescope (HST) itself.
In many ways, his story is a parable for the necessary resilience of
the scientific ego. A story of how good science is done, no matter
how imperfect the circumstances.
Fresh out of graduate school from Rice University, Hester took a position
as a postdoctoral assistant at the California Institute of Technology. Hester
worked for Jim Westfall, principal investigator for the Hubble project.
Hester expected the Hubble to launch within a year of his arrival.
Delay after delay postponed the launch. When the Space Shuttle Challenger
exploded in 1986, NASA put all projects that required launch vehicles
on indefinite hold. Hester found himself waiting for five years.
The HST was finally launched in 1990 and had its “First Light.”
The first pictures were downloaded from the orbiting telescope and
compared to ground-based images. Everyone expected success. Scientists
expected to see images 10 to 15 times sharper than ever seen before.
Instead, what the Hubble astronomers did do that day, in real-time and
in front of a live audience, was discover that something was not right.
Hester was by then an associate member of the Hubble team.
“I had the dubious distinction of being the guy who produced
that first picture,” he says. “It turned out that the telescope’s mirror
had a spherical aberration.”
The images were f lawed.
“It was one of the biggest debacles in the history of Big Science,”
the ASU astronomer says. “You know you’ve got a problem when Jay Leno
starts referring to a big mistake as ‘Hubbling’ something.”
Hubble’s initial failure could have been a career ending event for
many scientists. To their relief, however, Hester and others found that they
could still do good science with the f lawed orbiting telescope. Part of their
job became to figure out exactly what the f lawed Hubble could and could
not do. Their other job was to figure out how to eliminate the f law.
In 1993, while a faculty member at ASU, Hester was a member
of the science team that restored Hubble’s imaging capability with
the second generation Wide Field Planetary Camera 2 (WFPC2).
It was a simple solution—the WFPC2 was given the same problem
as the mirror, only in reverse.
The solution seemed easy, but the work to create and implement
the solution was not. “Building the second camera was a horribly difficult
process,” Hester recalls. “We were building it in a fishbowl. Working
20-hour days. Everything that anybody did was looked at in so many
different directions by so many different people. It really wasn’t
the best way to do this kind of project.”
The work paid off. When “First Light” came again in 1993, Hubble finally
had the capabilities its makers had intended. Hester and his colleagues
were greeted with applause when they unveiled some of his first images
at a special session during the American Astronomical Society meeting.
It has been more than 10 years since Hubble’s vision was corrected.
During that time, Hester has become a leading authority on the interstellar medium. His famous image of the Eagle Nebula now graces
a U.S. postage stamp.
“The work is great fun. It’s incredibly satisfying to have been part
of bringing this capability into existence. Now I have the opportunity
to use that capability to do some very fun science—the results of which
really blow people away.”
Based in part on repercussions from the Space Shuttle Columbia disaster,
in January 2004, NASA decided not to send any more shuttle visits to the
world’s first orbiting space telescope. By 2007, Hubble could die in orbit.
Or it could last until 2011, depending on when its batteries and gyroscopes
fail for good. When that happens, a visible eye on the universe will be gone.
But certainly not forgotten.
“We will suddenly feel blind,” says Hester. “Astronomers have
gotten used to being able to image objects with far better clarity
than is possible from the ground. Hubble has allowed us to take
that capability for granted.” Matthew Shindell
WINTER 2004 ASU RESEARCH
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