Eclectic Group of Galaxies Captured by Hubble

Like a photographer clicking random snapshots of a crowd of people, NASA’s Hubble Space Telescope has taken a view of an eclectic mix of galaxies. In taking this picture, Hubble’s Advanced Camera for Surveys was not looking at any particular target. The camera was taking a picture of a typical patch of sky, while Hubble’s infrared camera was viewing a target in an adjacent galaxy-rich region.

The jumble of galaxies in this image, taken in September 2003, includes a yellow spiral whose arms have been stretched by a possible collision [lower right]; a young, blue galaxy [top] bursting with star birth; and several smaller, red galaxies.

But the most peculiar-looking galaxy of the bunch ? the dramatic blue arc in the center of the photo ? is actually an optical illusion. The blue arc is an image of a distant galaxy that has been smeared into the odd shape by a phenomenon called gravitational lensing. This “funhouse- mirror effect” occurs when light from a distant object is bent and stretched by the mass of an intervening object. In this case the gravitational lens, or intervening object, is a red elliptical galaxy nearly 6 billion light-years from Earth. The red color suggests that the galaxy contains older, cooler stars.

The distant object whose image is smeared into the long blue arc is about 10 billion light-years away. This ancient galaxy existed just a few billion years after the Big Bang, when the universe was about a quarter of its present age. The blue color indicates that the galaxy contains hot, young stars.

Gravitational lenses can be seen throughout the sky because the cosmos is crowded with galaxies. Light from distant galaxies, therefore, cannot always travel through space without another galaxy getting in the way. It is like walking through a crowded airport. In space, a faraway galaxy’s light will travel through a galaxy that is in the way. But if the galaxy is massive enough, its gravity will bend and distort the light.

Long arcs, such as the one in this image, are commonly seen in large clusters of galaxies because of their huge concentrations of mass. But they are not as common in isolated galaxies such as this one. For the gravitational lens to occur, the galaxies must be almost perfectly aligned with each other.

Gravitational lenses yield important information about galaxies. They are a unique and extremely useful way of directly determining the amount of mass, including dark matter, in a galaxy. Galaxies are not just made up of stars, gas, and dust. An invisible form of matter, called dark matter, makes up most of a galaxy’s mass. A study of this newly discovered system, dubbed J033238-275653, was published in the Astrophysical Journal Letters. This study, together with similar observations, may allow astronomers to make the first direct measurements of the masses of bright, nearby galaxies.

Original Source: Hubble News Release

Chandra Sees a Star Flare Up

Observations with NASA’s Chandra X-ray Observatory captured an X-ray outburst from a young star, revealing a probable scenario for the intermittent brightening of the recently discovered McNeil’s Nebula. It appears the interaction between the young star’s magnetic field and an orbiting disk of gas can cause dramatic, episodic increases in the light from the star and disk, illuminating the surrounding gas.

“The story of McNeil’s Nebula is a wonderful example of the importance of serendipity in science,” said Joel Kastner of the Rochester Institute of Technology in Rochester, New York, lead author of a paper in the July 22 issue of Nature describing the X-ray results. “Visible-light images were made of this region several months before Jay McNeil made his discovery, so it could be determined approximately when and by how much the star flared up to produce McNeil’s Nebula.”

The small nebula, which lies in the constellation Orion about 1300 light years from Earth, was discovered with a 3-inch telescope by McNeil, an amateur astronomer from Paducah, Kentucky, in January 2004. In November 2002, a team led by Ted Simon of the Institute for Astronomy in Hawaii had observed the star-rich region with Chandra in search of young, X-ray emitting stars, and had detected several objects. Optical and infrared astronomers had, as part of independent surveys, also observed the region about a year later, in 2003.

After the announcement of McNeil’s discovery, optical, infrared and X-ray astronomers rushed to observe the region again. They found that a young star buried in the nebula had flared up, and was illuminating the nebula. This star was coincident with one of the X-ray sources discovered earlier by Simon.

Chandra observations obtained by Kastner’s group just after the optical outburst showed that the source had brightened fifty-fold in X-rays when compared to Simon’s earlier observation. The visible-light eruption provides evidence that the cause of the X-ray outburst is the sudden infall of matter onto the surface of the star from an orbiting disk of gas.

In general, the coupling of the magnetic field of the star and the magnetic field of its circumstellar disk regulates the inflow of gas from the disk onto the star. This slow, steady inflow suddenly can become much more rapid if a large amount of gas accumulates in the disk, and the disk and the star are rotating at different rates.

The differing rotation rates would twist and shear the magnetic field, storing up energy. This energy is eventually released in an energetic, X-ray producing outburst as the magnetic field violently rearranges back to a more stable state. During this period, a large amount of gas can fall onto the star, producing the observed optical and infrared outburst.

A new buildup of gas in the disk could lead to a new outburst in the future. Such a scenario may explain why the brightness of McNeil’s Nebula appears to vary with time. It is faintly present in surveys of this region of Orion in images taken in the 1960s, but absent from images taken in the 1950s and 1990s.

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Original Source: Chandra News Release

Wallpaper: Saturn’s Rings in Colour

Nine days before it entered orbit, Cassini captured this exquisite natural color view of of Saturn?s rings. The images that comprise this composition were obtained from Cassini?s vantage point beneath the ring plane with the narrow angle camera on June 21, 2004, from a distance of 6.4 million kilometers (4 million miles) from Saturn and a phase angle of 66 degrees. The image scale is 38 kilometers (23 miles) per pixel.

The brightest part of the rings, curving from the upper right to the lower left in the image, is the B ring. Many bands throughout the B ring have a pronounced sandy color. Other color variations across the rings can be seen. Color variations in Saturn’s rings have previously been seen in Voyager and Hubble Space Telescope images. Cassini’s images show that color variations in the rings are more pronounced in this viewing geometry than they are when seen from Earth. Saturn’s rings are made primarily of water ice. Since pure water ice is white, it is believed that different colors in the rings reflect different amounts of contamination by other materials such as rock or carbon compounds. In conjunction with other Cassini instruments, Cassini images will help to determine the composition of different parts of Saturn’s ring system.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Original Source: CICLOPS News Release

Space Initiative Gets Big Budget Cuts

President Bush’s new space initiative received a major setback this week when the members of a House appropriations subcommittee passed a tentative budget that would fund only a fraction of the President’s new plans. The panel suggested that NASA should receive $15.1 billion next year, which is a drop of $229 million from last year (NASA was actually hoping for a 5.6% increase). Development of the new Crew Exploration Vehicle would be delayed, and funding would be cut to Project Prometheus – a new nuclear propulsion technology. This isn’t a final approved budget, however, as there are many more steps for the final decision is made.

New Mars Meteorite Discovered

While rovers and orbiting spacecraft scour Mars searching for clues to its past, researchers have uncovered another piece of the red planet in the most inhospitable place on Earth — Antarctica.

The new specimen was found by a field party from the U.S. Antarctic Search for Meteorites program (ANSMET) on Dec. 15, 2003, on an ice field in the Miller Range of the Transantarctic Mountains, roughly 750 km (466 miles) from the South Pole. This 715.2-gram (1.6-pound) black rock, officially designated MIL 03346, was one of 1358 meteorites collected by ANSMET during the 2003-2004 austral summer.

Discovery of this meteorite occurred during the second full field season of a cooperative effort funded by NASA and supported by the National Science Foundation (NSF) to enhance recovery of rare meteorite types in Antarctica, in the hopes new martian samples would be found.

Scientists at the Smithsonian Institution’s National Museum of Natural History involved in classification of Antarctic finds said the mineralogy, texture and the oxidized nature of the rock are unmistakably martian. The new specimen is the seventh recognized member of a group of martian meteorites called the nakhlites, named after the first known specimen that fell in Nakhla, Egypt, in 1911.

Like the other martian meteorites, MIL 03346 is a piece of the red planet that can be studied in detail in the laboratory, providing a critical “reality check” for use in interpreting the wealth of images and data being returned by the spacecraft currently exploring Mars. Following the existing protocols of the U.S. Antarctic meteorite program, scientists from around the world will be invited to request samples of the new specimen for their own detailed research.

Nakhlites are significant among the known martian meteorites for several reasons. Thought to have originated within thick lava flows that crystallized on Mars approximately 1.3 billion years ago, and sent to Earth by a meteorite impact about 11 million years ago, the nakhlites are among the older known martian meteorites. As a result they bear witness to significant segments of the volcanic and environmental history of Mars.

The U.S. Antarctic Meteorite program is a cooperative effort jointly supported by NSF, NASA and the Smithsonian Institution. Antarctic field work is supported by grants from NASA and NSF to Case Western Reserve University, Cleveland; initial examination and curation of recovered Antarctic meteorites is supported by NASA at the astromaterials curation facilities at Johnson Space Center in Houston; and initial characterization and long-term curation of Antarctic meteorite samples is supported by NASA and the Smithsonian Institution at the National Museum of Natural History in Washington.

Details concerning initial characterization of the specimen and sample availability are available through a special edition of the Antarctic Meteorite Newsletter, to be immediately released on the Web at:

Antarctic Meteorite Newsletter

Original Source: NASA News Release

Satellites Spot Giant Rogue Waves

Once dismissed as a nautical myth, freakish ocean waves that rise as tall as ten-storey apartment blocks have been accepted as a leading cause of large ship sinkings. Results from ESA’s ERS satellites helped establish the widespread existence of these ‘rogue’ waves and are now being used to study their origins.

Severe weather has sunk more than 200 supertankers and container ships exceeding 200 metres in length during the last two decades. Rogue waves are believed to be the major cause in many such cases.

Mariners who survived similar encounters have had remarkable stories to tell. In February 1995 the cruiser liner Queen Elizabeth II met a 29-metre high rogue wave during a hurricane in the North Atlantic that Captain Ronald Warwick described as “a great wall of water? it looked as if we were going into the White Cliffs of Dover.”

And within the week between February and March 2001 two hardened tourist cruisers ? the Bremen and the Caledonian Star ? had their bridge windows smashed by 30-metre rogue waves in the South Atlantic, the former ship left drifting without navigation or propulsion for a period of two hours.

“The incidents occurred less than a thousand kilometres apart from each other,” said Wolfgang Rosenthal – Senior Scientist with the GKSS Forschungszentrum GmbH research centre, located in Geesthacht in Germany – who has studied rogue waves for years. “All the electronics were switched off on the Bremen as they drifted parallel to the waves, and until they were turned on again the crew were thinking it could have been their last day alive.

“The same phenomenon could have sunk many less lucky vessels: two large ships sink every week on average, but the cause is never studied to the same detail as an air crash. It simply gets put down to ‘bad weather’.”

Offshore platforms have also been struck: on 1 January 1995 the Draupner oil rig in the North Sea was hit by a wave whose height was measured by an onboard laser device at 26 metres, with the highest waves around it reaching 12 metres.

Objective radar evidence from this and other platforms ? radar data from the North Sea’s Goma oilfield recorded 466 rogue wave encounters in 12 years – helped convert previously sceptical scientists, whose statistics showed such large deviations from the surrounding sea state should occur only once every 10000 years.

The fact that rogue waves actually take place relatively frequently had major safety and economic implications, since current ships and offshore platforms are built to withstand maximum wave heights of only 15 metres.

In December 2000 the European Union initiated a scientific project called MaxWave to confirm the widespread occurrence of rogue waves, model how they occur and consider their implications for ship and offshore structure design criteria. And as part of MaxWave, data from ESA’s ERS radar satellites were first used to carry out a global rogue wave census.

“Without aerial coverage from radar sensors we had no chance of finding anything,” added Rosenthal, who headed the three-year MaxWave project. “All we had to go on was radar data collected from oil platforms. So we were interested in using ERS from the start.”

ESA’s twin spacecraft ERS-1 and 2 ? launched in July 1991 and April 1995 respectively ? both have a Synthetic Aperture Radar (SAR) as their main instrument.

The SAR works in several different modes; while over the ocean it works in wave mode, acquiring 10 by 5 km ‘imagettes’ of the sea surface every 200 km.

These small imagettes are then mathematically transformed into averaged-out breakdowns of wave energy and direction, called ocean-wave spectra. ESA makes these spectra publicly available; they are useful for weather centres to improve the accuracy of their sea forecast models.

“The raw imagettes are not made available, but with their resolution of ten metres we believed they contained a wealth of useful information by themselves,” said Rosenthal. “Ocean wave spectra provide mean sea state data but imagettes depict the individual wave heights including the extremes we were interested in.

“ESA provided us with three weeks’ worth of data ? around 30,000 separate imagettes ? selected around the time that the Bremen and Caledonian Star were struck. The images were processed and automatically searched for extreme waves at the German Aerospace Centre (DLR).”

Despite the relatively brief length of time the data covered, the MaxWave team identified more than ten individual giant waves around the globe above 25 metres in height.

“Having proved they existed, in higher numbers than anyone expected, the next step is to analyse if they can be forecasted,” Rosenthal added. “MaxWave formally concluded at the end of last year although two lines of work are carrying on from it ? one is to improve ship design by learning how ships are sunk, and the other is to examine more satellite data with a view to analysing if forecasting is possible.”

A new research project called WaveAtlas will use two years worth of ERS imagettes to create a worldwide atlas of rogue wave events and carry out statistical analyses. The Principal Investigator is Susanne Lehner, Associate Professor in the Division of Applied Marine Physics at the University of Miami, who also worked on MaxWave while at DLR, with Rosental a co-investigator on the project.

“Looking through the imagettes ends up feeling like flying, because you can follow the sea state along the track of the satellite,” Lehner said. “Other features like ice floes, oil slicks and ships are also visible on them, and so there’s interest in using them for additional fields of study.

“Only radar satellites can provide the truly global data sampling needed for statistical analysis of the oceans, because they can see through clouds and darkness, unlike their optical counterparts. In stormy weather, radar images are thus the only relevant information available.”

So far some patterns have already been found. Rogue waves are often associated with sites where ordinary waves encounter ocean currents and eddies. The strength of the current concentrates the wave energy, forming larger waves ? Lehner compares it to an optical lens, concentrating energy in a small area.

This is especially true in the case of the notoriously dangerous Agulhas current off the east coast of South Africa, but rogue wave associations are also found with other currents such as the Gulf Stream in the North Atlantic, interacting with waves coming down from the Labrador Sea.

However the data show rogue waves also occur well away from currents, often occurring in the vicinity of weather fronts and lows. Sustained winds from long-lived storms exceeding 12 hours may enlarge waves moving at an optimum speed in sync with the wind ? too quickly and they’d move ahead of the storm and dissipate, too slowly and they would fall behind.

“We know some of the reasons for the rogue waves, but we do not know them all,” Rosenthal concluded. The WaveAtlas project is scheduled to continue until the first quarter of 2005.

Original Source: ESA News Release

Tethys Revealed

Like a half-full Moon, cratered Tethys (1060 kilometers, 659 miles across) hangs before Cassini in this narrow angle camera view taken on July 3, 2004.

Voyager images showed a large fracture on Tethys about 750 kilometers (470 miles) long (not seen in this view.) Cassini will investigate this and other features on Tethys during two planned flybys, the first occurring on September 24, 2005.

The image was taken in visible light from a distance of 1.7 million kilometers (1 million miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of about 97 degrees. The image scale is 10 kilometers (6 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Original Source: CICLOPS News Release

You Have My Permission

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This permission is only for stuff in Universe Today, not any outside links. That belongs to them, not me. Also, most of the photos I use are license free (the NASA stuff, anyway), but you should always track back the original owner and make sure you’re allowed to use them.

If you’ve got a website, the easiest way to do this is with the syndication service. Put one line of HTML onto any webpage, and the latest edition of Universe Today will automatically pop in there. Here’s a link to the syndication instructions. Universe Today is also maintained in RSS format, so you can gather articles that way as well. Here’s a link to the RSS edition.

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Dark Energy Gets Another Boost

Using observations of 3,000 quasars discovered by the Sloan Digital Sky Survey (SDSS), scientists have made the most precise measurement to date of the cosmic clustering of diffuse hydrogen gas. These quasars–100 times more than have been used in such analyses in the past–are at distances of eight to ten billion light years, making them among the most distant objects known.

Filaments of gas between the quasars and the Earth absorb light in the quasar’s spectra, allowing researchers to map the gas distribution and to measure how clumpy the gas is on scales of one million light years. The degree of clumping of this gas, in turn, can answer fundamental questions such as whether neutrinos have mass and what the nature of dark energy is, hypothesized to be driving the accelerated expansion of the universe.

“Scientists have long studied the clustering of galaxies to learn about cosmology,” explained Uros Seljak of Princeton University, one of the SDSS researchers. “However, the physics of galaxy formation and clustering is very complicated. In particular, because most of the mass of the universe is made up of dark matter, an uncertainty arises from our lack of understanding of the relation between the distribution of galaxies (which we see) and the dark matter (which we can’t see but the cosmological models predict).” The gas filaments seen in the quasar spectra are thought to be distributed very much like the dark matter, removing this source of uncertainty.

“We have known for several years that quasar spectra are a unique tool for studying the distribution of dark matter in the early universe, but the quantity and quality of the SDSS data have made that vision a reality,” said David Weinberg of Ohio State University, a member of the SDSS team. “It’s amazing that we can learn so much about the structure of the universe 10 billion years ago.”

Seljak and his collaborators on the SDSS combined the analysis of the quasar spectra with measurements of galaxy clustering, gravitational lensing, and ripples in the Cosmic Microwave Background observed by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP). This gives the best determination to date of the clustering of matter in the universe from scales of one million light years to many billions of light years. This comprensive view allows detailed comparison with theoretical models for the history and constituents of the universe.

“This is the most rigorous test to date of the predictions of the cosmological model of inflation; inflation passes with flying colors,” added Seljak.

Inflationary theory states that right after the Big Bang the universe underwent a period of extremely rapid acceleration, during which tiny fluctuations were transformed into astronomical-sized wrinkles in space-time, ultimately observable in the clumping of astronomical objects. The theory of inflation predicts a very specific dependence of the degree of clustering with scale, which the current analysis strongly supports. Other scenarios, such as the cyclic universe theory, make very similar predictions and are also in agreement with the latest results.

Early analyses by the WMAP team and others had hinted at deviations in cosmic clustering from the prediction of inflation. If correct, this would have required a major revision of the current paradigm for origin of structure in the universe.

“The new data and the corresponding analysis substantially improves the observational precision of this test,” said Patrick McDonald of Princeton University and one of the finding’s authors. “The new results are in nearly perfect agreement with inflation.”

“The clustering of matter is a precise and powerful test of cosmological models, and the present analysis is consistent with, and extends our previous studies,” agreed Adrian Pope of The Johns Hopkins University, who led an earlier analysis of the clustering of SDSS galaxies.

The new analysis also provides the best information on the mass of the neutrino. Terrestial experiments–resulting in the 2002 Nobel Prize in Physics–have definitively shown that neutrinos have mass, but these experiments could only measure the difference in mass between the three different types of neutrinos known. The presence of neutrinos would affect the cosmic clustering on million-light-year scales, exactly the scales probed with the quasar spectra.

The new analysis suggests that the lightest neutrino mass has to be less than two times the previously measured mass difference. The new measurements also eliminate the possibility of an additional massive neutrino family suggested by some terrestrial experiments.

“Cosmology, the science of the very large, is able to tell us about properties of fundamental particles, such as neutrinos,” said Lam Hui of The U.S. Department of Energy’s Fermi National Accelerator Laboratory, who has been carrying out an independent analysis of these data, together with Scott Burles of MIT and others.

The new analysis also provides further support for the existence of dark energy, and suggests that dark energy is unchanging in time. This analysis provides the best limits on its time evolution to date.

“No evidence of dark energy changing in time has emerged so far, and the possibility that the universe will be torn apart by a big rip in the future is substantially reduced by these new results,” said Alexey Makarov of Princeton University, who also took part in this research.

Original Source: SDSS News Release

Shuttle Engine Tested for Return to Flight

Engineers at NASA’s Stennis Space Center (SSC) in Mississippi have successfully tested one of the engines that will carry the next Space Shuttle into orbit.

The test today was the first on a complete Space Shuttle Main Engine (SSME) that will be used on the Return to Flight mission. The engine will be shipped to NASA’s Kennedy Space Center for installation on the Space Shuttle Discovery. The Return to Flight mission, designated STS-114, will launch no earlier than next March and will go to the International Space Station.

The test began at about 4:59 p.m. EDT. It ran for 520 seconds, the length of time it takes a Space Shuttle to reach orbit. Initial indications are all test objectives were successfully met.

“It’s good to see hardware processing for Discovery moving forward at Stennis and other NASA centers,” said Michael Kostelnik, deputy associate administrator for International Space Station and Space Shuttle Programs. “Clearly, we’re making real progress in safely returning the Shuttle to flight and enabling the Vision for Space Exploration.”

“This Return to Flight test is a testimony to the hard work of the NASA and contractor team that developed and continues to improve the SSME’s capability to take humans to low Earth orbit safely,” said Miguel Rodriguez, director of the Propulsion Test Directorate at SSC. “It is a huge source of pride to the NASA and Boeing team to be part of this great program.”

Developed in the 1970s, the Space Shuttle Main Engine is the world’s most sophisticated reusable rocket engine. A Space Shuttle has three main engines. Each is 14 feet long, weighs about 7,000 pounds and is seven-and-a-half feet in diameter at the end of its nozzle. It generates almost 400,000 pounds of thrust.

Engineers conduct rigorous testing to verify an engine is ready to fly. The most modern versions of the SSME include a new high-pressure fuel turbopump that was first used in July 2001.

“The Space Shuttle Main Engine that flies today has gone through major upgrades and is safer, stronger and more reliable than the one that flew on the first Shuttle flight in 1981,” said Michael Rudolphi, Space Shuttle Propulsion Manager.

The Rocketdyne Propulsion and Power division of The Boeing Co. of Canoga Park, Calif., manufactures the Space Shuttle Main Engines. Pratt and Whitney, a United Technologies Company of West Palm Beach, Fla., builds the high-pressure turbopumps. The Space Shuttle Main Engine project is managed by the Space Shuttle Propulsion Office at NASA’s Marshall Space Flight Center in Huntsville, Ala. SSC conducts engine tests.

For more information about NASA’s Return to Flight efforts, visit:

http://www.nasa.gov/returntoflight

Original Source: NASA News Release