These images taken by NASA's Hubble Space Telescope show nine compact, ultradense galaxies as they appeared 11 billion years ago.
By SPACE.com Staff
Several newfound galaxies seen as they existed when the universe was young are packed with improbable numbers of stars.
Astronomers don't know what's going on.
The nine galaxies are 11 billion light-years away, which means the light astronomers are looking at left the galaxies 11 billion years ago, when the universe was less than 3 billion years old.
Each of the newly studied galaxies weighs about 200 billion times the mass of the sun yet is a mere 5,000 light-years across. Our Milky Way Galaxy is a fraction of that heft at roughly 3 million times the sun's mass, and yet it stretches across 100,000 light-years of space.
The compact galaxies have been furiously forming stars; each contains as many stars as a typical large galaxy of today, the new observations reveal.
"Seeing the compact sizes of these galaxies is a puzzle," said Pieter G. van Dokkum of Yale University, who led the study. "No massive galaxy at this distance has ever been observed to be so compact."
Since no modern galaxies — galaxies in the nearby universe — are so compact, the scientists assume compact galaxies from the early universe must have gotten much larger as they matured beyond the snapshots of ancient time now being studied. But nobody knows how.
"They would have to change a lot over 11 billion years, growing five times bigger," van Dokkum said. "They could get larger by colliding with other galaxies, but such collisions may not be the complete answer."
Astronomers used NASA's Hubble Space Telescope and the W.M. Keck Observatory on Mauna Kea, Hawaii to make the new observations, which were announced today and were detailed in the April 10 issue of the Astrophysical Journal Letters.
Van Dokkum and his colleagues had previously studied the galaxies in 2006 with the Gemini South Telescope to determine their distances, and showed that the stars are a half a billion to a billion years old. The most massive stars had already exploded as supernovae.
One reason these galaxies were so dense, van Dokkum suggested, involves the interaction of dark matter and hydrogen gas in the nascent universe. Dark matter is an invisible form of matter that accounts for most of the universe's mass. Shortly after the theoretical Big Bang, the universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in puddles of the invisible material, the thinking goes, and began spinning rapidly in dark matter's gravitational whirlpool, forming stars at a furious rate.
Based on the galaxies' mass, the astronomers estimated that the stars are spinning around their galactic disks at roughly 890,000 to 1 million mph (400 to 500 kilometers a second). Stars in today's galaxies, by contrast, are traveling at about half that speed because the setups are larger and rotate more slowly.
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The light we receive from distant sources is generated on the tiniest of scales. To explore the largest objects, such as galaxies, we have to first understand the smallest of objects, atoms and the particles making up atoms. The photons that we detect with our eyes and catch with our telescopes were generated in many different ways: sometimes by electrons hopping between different orbital levels in an atom, or other times by the energetic collisions of atomic nuclei. We now explore the ways in which photons of light arise, how they get from there to here, and what they can tell us about the objects that we observe.
We have concentrated thus far on optical photons (the ones that we can see with our eyes). As it turns out, our eyes respond to “visible” wavelengths because that is where the peak of the emission from the sun is located in the electromagnetic spectrum. If our eyes were most sensitive to infrared radiation, for example, we would see some things we can’t now see (body heat), but would miss a lot of other useful stuff. In this chapter, we’re going to talk more about visible light and the electromagnetic spectrum, of which visible light is a tiny subset. Think of it this way: If the electromagnetic spectrum is represented by a piano keyboard, then the visible part of the spectrum is but a single key or note. In the cosmic symphony, there are many notes, and we want to be able to hear them all. If you’re concerned that this sounds more like physics than astronomy, you’re right. But don’t be intimidated. Most of astronomy involves applications of physics principles, and we are convinced that understanding what you are seeing when you look at a star greatly enhances the experience of looking. Remember this astounding fact : When you look at the light from our sun or a distant star, you are witnessing the product of nuclear fusion reactions that are, every second, releasing more energy than any atomic explosion Earth has ever witnessed. Yet it is not just brute energy, but also information from the sky. Let’s take a closer look.
Next, relax. Don’t look too hard. We mean this as sincere and literal advice. Your eye’s sharpest color vision is in the center of your field of view. This is where color-receptor neurons known as cones are most densely concentrated. However, so-called rods, the visual receptors sensitive to black, white, and shades of gray, while insensitive to color, are more sensitive than cones to low levels of light. This means you can actually better see fainter objects with your peripheral vision than with your center-field vision. Learn to look askance at the stars. This practice is sometimes called “averted vision.” Using it, you will typically see fainter stars.
Peering through a telescope for extended periods is fun, but it can also be fatiguing. Don’t squint. Don’t peer. Step away from your telescope periodically to walk around. Relax and enjoy.
You’ll enjoy your astronomy sessions more, as well as reduce fatigue, if you practice keeping both eyes open when you look through the eyepiece. If you can’t resist the urge to close one eye, buy a pirate’s eye patch from the local toy store or costume shop. Then you can keep both eyes open without distraction and even feel like a real celestial navigator. A parrot on the shoulder is optional.
WASHINGTON (Reuters) - Images of colliding galaxies show them spinning, sliding and slipping into one another, wreaking stellar destruction that will give birth to new and larger galaxies.
The Maryland-based Space Telescope Science Institute released 59 new images from the Hubble Space Telescope on Thursday to celebrate the 18th anniversary of its launch.
"This new Hubble atlas dramatically illustrates how galaxy collisions produce a remarkable variety of intricate structures in never-before-seen detail," the Institute said in a statement.
"Astronomers observe only one out of a million galaxies in the nearby universe in the act of colliding. However, galaxy mergers were much more common long ago when they were closer together, because the expanding universe was smaller."
The color images, available online, are a look back in time. It takes hundreds of millions of years for galaxies to merge and the light from their stars has traveled for hundreds of millions of years across space.
Because it orbits outside the Earth's atmosphere, Hubble's cameras can take extremely sharp images.
Its future was controversial, as it requires regular servicing by space shuttle astronauts to stay in working condition.
After the 2003 Columbia space shuttle disaster, a servicing mission initially planned for 2004 was canceled.
NASA at one point was planning to abandon the telescope, hugely popular among astronomers. After an outcry, the U.S. space agency relented and a final Hubble servicing mission is scheduled for August.
In 2013, the James Webb Space Telescope is scheduled to replace Hubble
You have some learning to get under your belt, but right now, neophyte that you are, you can do something to enhance your experience. Unless you are looking at the bright moon, don’t rush to the eyepiece until you have allowed your vision to become “dark adapted.” This natural adjustment will greatly enhance your ability to see faint objects—and it will make brighter objects that much more exciting. Adapting your eyes to the dark requires about 15 minutes away from sources of light. If somebody shines an uncovered flashlight in your eyes, you’ll have to become dark adapted all over again. Red light, however, will not reverse dark adaptation. For those on liberal budgets, there are specially made, compact flashlights with red bulbs. For the rest of us, either equip your flashlight with a dark red filter (you can use red acetate purchased from a hobby shop) or (less effectively) simply put a red sock over the flashlight. This way, you’ll be able to see what you are doing and even consult star maps without spoiling your dark adaptation.
Understandably, you will be eager to try out your new telescope. Here are a few words of advice: Expect to be thrilled—immediately—by the spectacle of the moon, with its sharply delineated craters and mountains. Point your telescope elsewhere, however, and you may be disappointed—at least until you learn more about what to look for. We have become spoiled by dazzling images from the Hubble Space Telescope, orbiting above our atmosphere and toting the most sophisticated instruments available. No, your telescope won’t duplicate the performance of Hubble. But the point is that it is your telescope, and the photons of light that left the Orion Nebula are striking your retina. The experience is yours.
Your first impulse may be to blame any disappointment you feel on your telescope. Resist the impulse. As you learn what to look for—and as you come to appreciate the significance of what you see—you will derive great satisfaction from your instrument.
ABC News has been given unprecedented access to the astronauts, scientists and engineers involved in the intensive — and some say risky — shuttle mission to repair the Hubble Space Telescope later this year.
Time is running out for Hubble. If its batteries and gyroscopes aren't replaced soon, the most famous of space telescopes will simply quit functioning.
If all goes well, the Space Shuttle Atlantis mission, dubbed STS 125, will launch in August to service Hubble. ABC News will follow the crew as it trains for this mission.
This will be the last time a space shuttle visits Hubble. Everyone involved knows they must make every single minute of the mission count to ensure Hubble will continue to explore the universe until the replacement Webb telescope can be launched sometime in the next decade.
What makes this mission risky?
Unlike most recent shuttle missions, this one will not be docking at the International Space Station. If Atlantis encounters an emergency, Hubble's orbit is so far from the space station, that the Atlantis crew will not be able to reach it.
But NASA is ready with an unprecedented backup plan. For the first time, when the Atlantis astronauts launch to repair Hubble, a second shuttle will already be on the other launch pad at the Kennedy Space Center, ready to go within days if its colleagues on the Hubble mission encounter a problem.
It is easy to see why the Hubble mission is the most talked about mission of the year at NASA and overshadows the global effort to build the International Space Station.
Hubble is the telescope that can look back in time; the space station is still a construction project, albeit one of the most complicated ever undertaken.
Just what kind of allure does the Hubble Space Telescope have that the International Space Station doesn't? Apollo 7 astronaut Walt Cunningham says it's all about perception.
"The International Space Station is the most incredible engineering achievement in history. It exceeds the Panama Canal or the pyramids if you will, but it doesn't capture the public's fancy, because it looks like a truck driving back and forth delivering construction materials," he said.
Hubble was deployed in 1990, and it wasn't an instant hit. Its first images were blurry because of an embarrassing failure to notice that the shape of the telescope's primary mirror was not accurate.
A daring space shuttle mission to install corrective lenses fixed that in 1993. That troubled beginning is part of its mystique, according to Sandra Faber of the University of California at Santa Cruz.
"It was such a disaster, but it was like chestnuts pulled out of the fire at the last minute. It is the ultimate American can-do story," she said.
And oh what Hubble can do! Hubble has allowed scientists to estimate the age of the universe — 14 billion years.
Faber points to Hubble's discoveries about galaxies. "First and foremost for me as [a] student of galaxy formation, Hubble was the first telescope to look back in time and show us infant galaxies, in the process of being born. That's a first. To use a telescope as a time machine looking back billions of years — that is a terrific legacy."
Matt Mountain, director of the Hubble Space Telescope, says the telescope's popularity is simple to explain.
"It allows us to see the universe in a way we don't have to explain. A picture is worth 1,000 words and so we look back in time at some of the earliest galaxies," he said.
"What we deliver back are stunning images of these fairly early galaxies," Mountain said. "And so we can't disassociate science from the image because there's actually great meaning in the science and the public actually engages in that when they look at these great pictures."
Steve Hawley is one of the astronauts who deployed Hubble. He is also an astronomer and thinks he understands why Hubble resonates with so many people.
"The pictures are breathtaking; the science discoveries are mind boggling. I will be sitting next to someone on an airplane and they will ask me what do I do, and I say I work for NASA and they'll say 'oh NASA,' and they think the shuttle goes to the moon and we launch from Houston but they know about Hubble."
What makes people remember Hubble when they aren't ordinarily interested in space? Hawley has wondered about that.
"Whatever it turns out to be we need to learn that lesson because we need to apply it to other things we are doing. If it's the pictures, if it's the drama is, you know you can always pick up the paper and read something new Hubble has done, maybe people think they are getting value for their tax dollars, but as far as I know we never really studied it, or asked someone who knows how to do that kind of thing to study it, and tell us what it really was about Hubble that people found so appealing."
