New Explaination for Cosmic Rays

Image credit: Hubble
University of California scientists working at Los Alamos National Laboratory have proposed a new theory to explain the movement of vast energy fields in giant radio galaxies (GRGs). The theory could be the basis for a whole new understanding of the ways in which cosmic rays — and their signature radio waves — propagate and travel through intergalactic space.

In a paper published this month in The Astrophysical Journal Letters, the scientists explain how magnetic field reconnection may be responsible for the acceleration of relativistic electrons within large intergalactic volumes. That is, the movement of charged particles in space that are originally energized by massive black holes.

“If our understanding of this process is correct,” says Los Alamos astrophysicist Philipp Kronberg, “it could be a paradigm shift in current thinking about the nature of GRGs and cosmic rays.”

Researchers still do not fully understand why magnetic field reconnection occurs, but this much is known: a deeper understanding of the mechanism could have important applications here on Earth, such as the creation of a system of magnetic confinement for fusion energy reactors.

If the Los Alamos scientists’ theory is correct, the discovery also has wide-ranging astrophysical consequences. It implies that magnetic field reconnection or some other highly efficient field-to-particle energy conversion process could be a principal source of all extragalactic radio sources, and possibly also the mysterious “Ultra High Energy Cosmic Ray particles”.

Giant radio galaxies are vast celestial objects that emit a continuum of radio wavelengths detectable with radio telescopes like those at the Very Large Array in Socorro, N.M. Using comprehensive data on seven of the largest radio galaxies in the Universe gathered over the past two decades, the researchers were able to study cosmic ray energy fields that are expelled from the GRGs centers — which are almost certain to contain supermassive black holes — outward as much as a few millions of light years into intergalactic space (1 light year = 5,900,000,000,000 miles).

What the Los Alamos researchers concluded was that the high energy content of these giant radio galaxies, their large ordered magnetic field structures, the absence of strong large-scale shocks and very low internal gas densities point to a direct and efficient conversion of the magnetic field to particle energy in a process that astrophysicists call magnetic field reconnection. Magnetic field reconnection is a process where the lines of a magnetic field connect and vanish, converting the field’s energy into particle energy. Reconnection is considered a key process in the sun’s corona for the production of solar flares and in fusion experiment devices called tokamaks. It also occurs in the interaction between the solar wind and the Earth’s magnetic field and is considered a principal cause of magnetospheric storms.

The research determined that the measurement of the total energy content of at least one of these giant radio galaxies — which is believed to have at its center a black hole with a mass equal to 100 million times that of our sun — was 10 61 ergs. Ergs are a measure of energy where one erg is the amount of energy needed to lift one gram of weight a distance of one centimeter. This energy level of 10 61 ergs is several times more than the thermonuclear energy that could be released by all the stars in a galaxy, offering substantial proof to the researchers that the source of the measured energy could not be typical solar fusion or even supernovae.

In addition to the high energy content, the large, orderly structure of the magnetic field and the absence of strong large-scale shocks — like those that might be present from a supernova explosion — led the scientists to believe that the process of magnetic field reconnection is at work.

In addition to Kronberg, the theory is the result of work by Los Alamos scientists Stirling Colgate, Hui Li and Quentin Dufton. The research was funded by Los Alamos Laboratory-Directed Research and Development (LDRD) funding. LDRD funds basic and applied research and development focusing on creative concepts selected at the discretion of the Laboratory Director.

Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA’s Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring safety and confidence in the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction and improving the environmental and nuclear materials legacy of the cold war. Los Alamos’ capabilities assist the nation in addressing energy, environment, infrastructure and biological security problems.

Original Source: Los Alamos National Laboratory News Release

Book Review: Strange Matters

The frontiers of space and time are where the physicists and cosmologist are positioned in their search for an understanding of our surroundings. These theoreticians and experimenters are looking for smaller and smaller particles in our space and at the same time are considering the possibility of more than one universe. For them, time may or may not have begun with the start of the universe. It is a relative dimension, and it may even consist of more than one dimension. As equipment gets more advanced, whether stronger atom smashers or more powerful telescopes, these experts obtain more and more clues about existence and often more and more questions.

In our surroundings stranger and stranger ideas are contemplated. There may be planets without central stars. Our universe may start growing with hyperinflation, slow down growth and then speed up again. Patterns of galaxies look like they grow on bubbles. While great attractors have matter streaming into them. Dark matter and negative energy may be more important than visible matter and known energy in keeping our universe together. The universe could be expanding and continue to do so forever, in steady state, or it could be contracting where a big crunch brings the universe back to that which existed before the big bang. There may be other universes alongside or intertwined with our own, or there may be multiple copies of our universe. Theoreticians are looking at their equations and current observations and trying to make reason of it all. Experimenters, of course, would cherish the idea of travelling about the galaxies so as to equally provide for an understanding. However, for now, being stuck on a planet forces them to make the most of whatever is at hand.

Theoreticians rely, for the most part, on mathematics. Math is a standardized means of expressing relationships between entities. Because of its formality, a mathematical equation will often provide more than just the one answer needed and theoreticians will pronounce new elements or conditions based on these alternate answers. Though these can appear, at first, to be nonsensical, experimenters might then establish proof of the validity of these answers. This method of mathematical ‘prediscovery’ has lead to such exotic concepts as strange matter, dark energy, negative pressure and fractional electric charges. And the theoreticians and experimenters are an essential combination in advancing our understanding.

However, even with the steady advances being made, there still remains their greatest challenge, to combine gravitational force with electromagnetism. Physicists are looking hard for this unifying theory and, though many pronouncements are made, there is still no proof for any particular one. Super symmetry or string theory is a strong candidate. By vibrating at different frequencies or notes, a string could mimic any elementary particle. Recent theories have overcome earlier anomalies in the conservation laws and actually provide tens to hundreds of possibilities. These are now considered to be equivalent candidates as each can fold into the other due to the concept of topology. Experimenters, however, will be challenged as the largest of these strings are believed to be on the order of 10-31 cm. Needless to say they aren’t able to do this, at least yet.

And this is one of the curiosities that Tom raises. Is the universe set in a specific way, for a specific reason, or is it the mathematics that defines the state of the universe? This is termed by the cosmologists as the anthropic principal. That is, people are needed to define that in which they exist so perhaps, without people, this universe wouldn’t exist or at least it wouldn’t the way we know it. Further, mathematics is a human construct. So how is it continually able to predict knowledge? And how is it we can say something exists even though we can’t detect it with any of our five senses? Still, with all the good that has come from curiosity it is fortuitous that people are curious.

Tom’s book is a wonderful tour de force of current thinking in physics and cosmology. It discusses much of the progress in scientific ideas, from early principles such as conservation of energy through to the wave/particle concept of light and beyond. Often Tom includes the results of personal interviews and this adds solid credence to the work. Also, though mathematics is often raised, the book has no equations. Albeit, a good understanding and interest of physics and physical principles will allow you to get the most out of this tour.

Though I do appreciate the ability of a journalist to capture the essence of a story, there are times this book reads like a collection of headlines rather than a continuous connected prose. The subject is the same throughout, i.e. physics and cosmology, but it is difficult to grasp what, if any, overall point is being made. The book would greatly benefit with the presentation of a reason for research and analysis in this area.

The physicists and cosmologists are indeed finding matter to be strange. Tom Siegfried in his book Strange Matters, Undiscovered Ideas at the Frontiers of Space and Time will bring the reader up to speed on who is doing what to provide a better understanding of our cosmos. Tom’s journalistic skills allow very complex topics to be easily read and understood by the uninitiated. Read this book and you will realize that, though perhaps strange, the ideas being contemplated at the forefront of space and time show humans to be a gifted species with great potential.

Read more reviews and descriptions from Amazon.com

Review by Mark Mortimer

Computer to Simulate Exploding Star

Image credit: University of Chicago
University scientists are preparing to run the most advanced supercomputer simulation of an exploding star ever attempted.

Tomasz Plewa, Senior Research Associate in the Center for Astrophysical Thermonuclear Flashes and Astronomy & Astrophysics, expects the simulation to reveal the mechanics of exploding stars, called supernovae, in unprecedented detail.

The simulation is made possible by the U.S. Department of Energy?s special allocation of an extraordinary 2.7 million hours of supercomputing time to the Flash Center, which typically uses less than 500,000 hours of supercomputer time annually.

?This is beyond imagination,? said Plewa, who submitted the Flash Center proposal on behalf of a research team at the University and Argonne National Laboratory.

The Flash Center project was one of three selected to receive supercomputer time allocations under a new competitive program announced last July by Secretary of Energy Spencer Abraham.

The other two winning proposals came from the Georgia Institute of Technology, which received 1.2 million processor hours, and the DOE?s Lawrence Berkeley National Laboratory, which received one million processor hours.

The supercomputer time will help the Flash Center more accurately simulate the explosion of a white dwarf star, one that has burned most or all of its nuclear fuel. These supernovae shine so brightly that astronomers use them to measure distance in the universe. Nevertheless, many details about what happens during a supernova remain unknown.

Simulating a supernova is computationally intensive because it involves vast scales of time and space. White dwarf stars gravitationally accumulate material from a companion star for millions of years, but ignite in less than a second. Simulations must also account for physical processes that occur on a scale that ranges from a few hundredths of an inch to the entire surface of the star, which is comparable in size to Earth.

Similar computational problems vex the DOE?s nuclear weapons Stockpile Stewardship and Management Program. In the wake of the Comprehensive Test Ban Treaty, which President Clinton signed in 1996, the reliability of the nation?s nuclear arsenal must now be tested via computer simulations rather than in the field.

?The questions ultimately are how is the nuclear arsenal aging with time, and is your code predicting that aging process correctly?? Plewa said.

Flash Center scientists verify the accuracy of their supernovae code by comparing the results of their simulations both to laboratory experiments and to telescopic observations. Spectral observations of supernovae, for example, provide a sort of bar code that reveals which chemical elements are produced in the explosions. Those observations currently conflict with simulations.

?You want to reconcile current simulations with observations regarding chemical composition and the production of elements,? Plewa said.

Scientists also wish to see more clearly the sequence of events that occurs immediately before a star goes supernova. It appears that a supernova begins in the core of a white dwarf star and expands toward the surface like an inflating balloon.

According to one theory, the flame front initially expands at a relatively ?slow? subsonic speed of 60 miles per second. Then, at some unknown point, the flame front detonates and accelerates to supersonic speeds. In the ultra-dense material of a white dwarf, supersonic speeds exceed 3,100 miles per second.

Another possibility: the initial subsonic wave fizzles when it reaches the outer part of the star, leading to a collapse of the white dwarf, the mixing of unburned nuclear fuel and then detonation.

?It will be very nice if in the simulations we could observe this transition to detonation,? Plewa said.

Flash Center scientists already are on the verge of recreating this moment in their simulations. The extra computer time from the DOE should push them across the threshold.

The center will increase the resolution of its simulations to one kilometer (six-tenths of a mile) for a whole-star simulation. Previously, the center could achieve a resolution of five kilometers (3.1 miles) for a whole-star simulation, or 2.5 kilometers (1.5 miles) for a simulation encompassing only one-eighth of a star.

The latter simulations fail to capture perturbations that may take place in other sections of the star, Plewa said. But they may soon become scientific relics.

?I hope by summer we?ll have all the simulations done and we?ll move on to analyze the data,? he said.

Original Source: University of Chicago News Release

Sea Launch Prepares for DIRECTV Launch

Image credit: Sea Launch
The Sea Launch team arrived at the launch site on the equator yesterday in preparation for the launch of the DIRECTV 7S broadcast satellite for DIRECTV Inc. on Tuesday, May 4, at 5:22am PDT (12:22:00 GMT), at the opening of a two-hour launch window. All systems are proceeding on schedule.

With launch site operations now underway, the marine crew has ballasted the Odyssey Launch Platform about 65 feet to ensure stability. The Sea Launch Commander (Assembly and Command Ship), will be stationed alongside the Odyssey, throughout the weekend, frequently connected by a link bridge that enables foot traffic between the two vessels.

The team will initiate a 72-hour launch countdown on Saturday, May 1. On the day before launch, the platform will be evacuated, with all personnel safely stationed on the ship, three miles from the platform, throughout launch operations. The rocket will be rolled out of its environmentally-protected hangar and automatically erected on the launch pad at L-27 hours.

Sea Launch?s Zenit-3SL vehicle will lift the 5,483 kg (12,063 lb.) DIRECTV 7S satellite to geosynchronous transfer orbit, on its way to a final orbital position at 119 degrees West Longitude. DIRECTV 7S, the second spot beam satellite in the DIRECTV fleet, will use highly focused spot beam technology to provide DIRECTV with the capacity to deliver local channels to 42 additional markets, expanding local channel coverage to a total of 106 markets. The satellite is also capable of operating from 101 degrees West Longitude, the primary orbital slot for DIRECTV. Built by Space Systems/Loral (SS/L) at their state-of-the-art manufacturing facility in Palo Alto, Calif., the 1300-series spacecraft is one of several high capacity direct-to-home (DTH) broadcast satellites SS/L has produced for DIRECTV, the leading U.S. digital television provider.

Sea Launch will carry a live satellite feed and streaming video of the entire mission, beginning at 5:00 am PDT (12:00:00 GMT). To downlink the broadcast, transponder coordinates are posted at: www.boeing.com/nosearch/sealaunch/broadcast.html
A simultaneous webcast will be posted at:
www.sea-launch.com/current_index_webcast.html

Sea Launch Company, LLC, headquartered in Long Beach, Calif., and marketed through Boeing Launch Services ( www.boeing.com/launch ), is the world?s most reliable commercial launch services provider. With the advantage of a launch site on the Equator, the proven Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, yielding best value plus schedule assurance. Sea Launch offers the most direct and cost-effective route to geostationary orbit. For additional information, visit the Sea Launch website at: www.sea-launch.com

Original Source: Boeing News Release

Binary Pulsar System Confirmed

Image credit: NASA/JPL
The only known gravitationally bound pair of pulsars — extremely dense, spinning stars that beam radio waves — may be pirouetting around each other in an intricate dance.

“Pulsars are intriguing and puzzling objects. They pack as much mass as the Sun crammed into an object with a cross-sectional area about as large as Boston,” said Fredrick Jenet of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Jenet and Scott Ransom of McGill University, Montreal, Quebec, Canada, have developed a theoretical model to explain the behavior of this one-of-a-kind set of pulsars.

“The physics of radio pulsar emission has eluded researchers for more than three decades,” Jenet said. “This system may be the ‘Rosetta stone’ of radio pulsars, and this model is one step toward its translation.”

The research appears in the April 29 issue of the journal Nature. Jenet and Ransom studied the recently-discovered double pulsar system, in which two spinning pulsars orbit each other.

The discovery of the two-star system, officially named PSR J0737- 3039B, was announced in 2003 by a multinational team of researchers from Italy, Australia, the United Kingdom and the United States. Those researchers proposed that the duo contained one spinning pulsar and a neutron star. Later in 2003, scientists working at the Parkes Observatory in New South Wales, Australia, determined that both stars are actually pulsars. This discovery marked the first known example of a “binary,” or double, pulsar system. The stars are referred to as A and B.

Pulsars emit high-intensity radio radiation into a narrow beam. As the pulsar rotates, this beam moves in and out of our line of sight. Hence, we see periodic bursts of radio radiation. In this sense, a pulsar works like a lighthouse, in which the light may be on all the time, but it appears to blink on and off. Scientists were surprised to find that the B pulsar is on only at certain locations in its orbit. “It’s as though something is turning B on and off,” Jenet said.

According to Jenet and Ransom, this “something” is closely related to the radio emission beam emanating from the A pulsar. They believe that B becomes bright when it is illuminated by emission from A. Jenet and Ransom used Einstein’s Theory of General Relativity to predict the future evolution of this pulsar system. The theory implies that gravitational effects will change the emission pattern of A, which will then alter the exact orbital locations where B becomes bright.

The double pulsar system is located about 2,000 light years, or 10 million billion miles, from Earth. Jenet and Ransom based their research on observations made at the Green Bank Telescope in West Virginia.

Original Source: NASA/JPL News Release

Wallpaper: Bug Nebula

Image credit: Hubble
The Bug Nebula, NGC 6302, is one of the brightest and most extreme planetary nebulae known. At its centre lies a superhot dying star smothered in a blanket of ?hailstones?. A new Hubble image reveals fresh detail in the wings of this ?cosmic butterfly?.

This image of the Bug Nebula, taken with the NASA/ESA Hubble Space Telescope (HST), shows impressive walls of compressed gas. A torus (?doughnut?) shaped mass of dust surrounds the inner nebula (seen at the upper right).

At the heart of the turmoil is one of the hottest stars known. Despite an extremely high temperature of at least 250 000 degrees Celsius, the star itself has never been seen, as it shines most brightly in the ultraviolet and is hidden by the blanket of dust, making it hard to observe.

Chemically, the composition of the Bug Nebula also makes it one of the more interesting objects known. Earlier observations with the European Space Agency’s Infrared Space Observatory (ISO) have shown that the dusty torus contains hydrocarbons, carbonates such as calcite, as well as water ice and iron. The presence of carbonates is interesting. In the Solar System, their presence is taken as evidence for liquid water in the past, because carbonates form when carbon dioxide dissolves in liquid water and forms sediments. But its detection in nebulae such as the Bug Nebula, where no liquid water has existed, shows that other formation processes cannot be excluded.

Albert Zijlstra from UMIST in Manchester, UK, who leads a team of astronomers probing the secrets of this extreme object, says: ?What caught our interest in NGC 6302 was the mixture of minerals and crystalline ice – hailstones frozen onto small dust grains. Very few objects have such a mixed composition.?

The dense, dark dust torus around the central star contains the bulk of the measured dust mass and is something of a mystery to astronomers. They believe the nebula was expelled around 10 000 years ago, but do not understand how it formed or how long the dust torus can survive evaporation by the very hot central star.

Original Source: ESA News Release

NASA’s X-Prize Looking for Ideas

The NASA program that offers cash prizes for the development of new capabilities to help meet the agency’s exploration and program goals is conducting its first workshop June 15-16 at the Hilton Hotel, Washington.

Centennial Challenges is a novel program of challenges, competitions, and prizes. NASA plans to tap the innovative talents of the nation to make revolutionary, breakthrough advances to support Vision for Space Exploration and other NASA priorities.

“Centennial Challenges is a small but potentially high-leverage investment by NASA to help address some of our most difficult hurdles in research and exploration,” said NASA Administrator Sean O’Keefe. “I look forward to stimulating competitions and very innovative wins that advance the nation’s Vision for Space Exploration,” he added.

The goal of Centennial Challenges is to stimulate innovation in fundamental technologies, robotic capabilities, and very low-cost space missions by establishing prize purses for specific achievements in technical areas of interest to NASA. By making awards based on achievements, not proposals, NASA hopes to bring innovative solutions from academia, industry, and the public to bear on solar system exploration and other technical challenges.

“From 18th century seafaring, early 20th century aviation to today’s private sector space flight, prizes have played a key role in spurring new achievements in science, technology, engineering, and exploration,” said Craig Steidle, NASA’s Associate Administrator for Exploration Systems. “The Centennial Challenges Program is modeled on the successful history of past prize contests, and I am proud the Office of Exploration Systems is shepherding this path-finding program for NASA,” he added.

“This workshop will help NASA develop challenges that are of high value to the agency,” said Brant Sponberg, Centennial Challenges Program Manager. “The workshop also will provide input into what challenges NASA announces this year and next year and what the rules for those competitions will be. It should be an invigorating way to lay the groundwork for this exciting program,” he said.

NASA invites individuals and organizations interested in competing to attend the 2004 Centennial Challenges Workshop. The agenda and registration information for the workshop is available on the Internet at:

http://www.tisconferences.com/nasa_centennial/

NASA plans annual Centennial Challenges workshops. For information about the program on the Internet, visit:

centennialchallenges.nasa.gov

Original Source: NASA News Release

Mars Express Radar Deployment Delayed

Image credit: ESA
The MARSIS team has advised ESA to delay the deployment of the MARSIS radar instrument on board Mars Express, scheduled for this week.

New and improved computer models suggest that, during deployment, the radar booms may swing back and forth with larger amplitudes than previously expected. If this happened, the booms might come too close to delicate components of the spacecraft body. Further simulations and tests are under way to better understand the situation.

The two main radar booms are 20-metre long hollow cylinders, of 2.5 centimetres diameter, folded up in a box like a concertina (accordion). When the box is opened, the elastic energy of the compressed glass-fibre booms will let them unfold like a jack-in-the-box.

After the booms spring out, they will eventually lock in a straight line, taking up the shape that they had before being folded into the box. The deployment procedure of each boom is expected to last about 10 minutes.

Simulations carried out four years ago by the radar boom’s manufacturer, Astro Aerospace, California, USA, indicated that the deployment should be smooth, without significantly swinging back and forth. However, the radar team has now advised ESA that a new and refined analysis of the boom dynamics indicates that a sort of “backlash” might take place before the boom locks into its position.

Although a successful deployment is not in question, Mars Express mission managers want to make sure that the booms are not subjected to excessive mechanical stress and that they do not interfere with the spacecraft as they deploy.

The MARSIS team and their industrial contractors are now performing further tests and simulations to confirm that the deployment will have no impact on the safety of the spacecraft. These simulations will then be reviewed by ESA’s experts. Based on the results, expected within a few weeks, ESA will decide when and how to activate MARSIS.

MARSIS will study the sub-surface of Mars to a depth of a few kilometres. The instrument’s antennas will send radio waves towards the planet and analyse how they are reflected by any surface that they encounter. In this way, MARSIS can investigate the sub-surface mineralogical composition and will reveal the presence of any underground reservoir of water or ice.

Original Source: ESA News Release

Saturn in Full Colour

Image credit: NASA/JPL/Space Sciences
Saturn and its rings completely fill the field of view of Cassini’s narrow angle camera in this natural color image taken on March 27, 2004. This is the last single `eyeful’ of Saturn and its rings achievable with the narrow angle camera on approach to the planet. From now until orbit insertion, the rings will be larger than the camera’s field of view. The image is a composite of three exposures in red, green, and blue, taken when the spacecraft was 47.7 million kilometers (29.7 million miles) from the planet. The image scale is 286 kilometers (178 miles) per pixel.

Color variations between atmospheric bands and features in the southern hemisphere of the planet, as well as subtle color differences across Saturn’s middle B ring, are now more distinct than ever. Color variations generally imply different compositions. The nature and causes of any compositional differences in both the atmosphere and the rings are major questions to be investigated by Cassini scientists as the mission progresses.

The bright blue sliver of light in the northern hemisphere is sunlight passing through the Cassini Division in Saturn’s rings and being scattered by the cloud-free upper atmosphere.

Two faint dark spots are visible in the southern hemisphere. These spots are close to the latitude where Cassini saw two storms merging in mid-March. The fate of the storms visible here is unclear. They are getting close and will eventually merge or squeeze past each other. Further analysis of such dynamic systems in Saturn’s atmosphere will help scientists understand their origins and complex interactions.

Moons visible in this image are (clockwise from top right): Enceladus (499 kilometers, 310 miles across), Mimas (398 kilometers, 247 miles across), Tethys (1060 kilometers, 659 miles across), and Epimetheus (116 kilometers, 72 miles across). Epimetheus is dim and appears just above the left edge of the rings. Brightnesses have been exaggerated to aid visibility.

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

ESO Images Cosmic Collision

Image credit: ESO
Stars like our Sun are members of galaxies, and most galaxies are themselves members of clusters of galaxies. In these, they move around among each other in a mostly slow and graceful ballet. But every now and then, two or more of the members may get too close for comfort – the movements become hectic, sometimes indeed dramatic, as when galaxies end up colliding.

ESO shows an example of such a cosmic tango. This is the superb triple system NGC 6769-71, located in the southern Pavo constellation (the Peacock) at a distance of 190 million light-years.

This composite image was obtained on April 1, 2004, the day of the Fifth Anniversary of ESO’s Very Large Telescope (VLT). It was taken in the imaging mode of the VIsible Multi-Object Spectrograph (VIMOS) on Melipal, one of the four 8.2-m Unit Telescopes of the VLT at the Paranal Observatory (Chile). The two upper galaxies, NGC 6769 (upper right) and NGC 6770 (upper left), are of equal brightness and size, while NGC 6771 (below) is about half as bright and slightly smaller. All three galaxies possess a central bulge of similar brightness. They consist of elderly, reddish stars and that of NGC 6771 is remarkable for its “boxy” shape, a rare occurrence among galaxies.

Gravitational interaction in a small galaxy group
NGC 6769 is a spiral galaxy with very tightly wound spiral arms, while NGC 6770 has two major spiral arms, one of which is rather straight and points towards the outer disc of NGC 6769. NGC 6770 is also peculiar in that it presents two comparatively straight dark lanes and a fainter arc that curves towards the third galaxy, NGC 6771 (below). It is also obvious from this new VLT photo that stars and gas have been stripped off NGC 6769 and NGC 6770, starting to form a common envelope around them, in the shape of a Devil’s Mask. There is also a weak hint of a tenuous bridge between NGC 6769 and NGC 6771. All of these features testify to strong gravitational interaction between the three galaxies. The warped appearance of the dust lane in NGC 6771 might also be interpreted as more evidence of interactions.

Moreover, NGC 6769 and NGC 6770 are receding from us at a similar velocity of about 3800 km/s – a redshift just over 0.01 – while that of NGC 6771 is slightly larger, 4200 km/s.

A stellar baby-boom
As dramatic and destructive as this may seem, such an event is also an enrichment, a true baby-star boom. As the Phoenix reborn from its ashes, a cosmic catastrophe like this one normally results in the formation of many new stars. This is obvious from the blueish nature of the spiral arms in NGC 6769 and NGC 6770 and the presence of many sites of star forming regions.

Similarly, the spiral arms of the well-known Whirlpool galaxy (Messier 51) may have been produced by a close encounter with a second galaxy that is now located at the end of one of the spiral arms; the same may be true for the beautiful southern galaxy NGC 1232 depicted in another VLT photo (PR Photo 37d/98).

Nearer to us, a stream of hydrogen gas, similar to the one seen in ESO PR Photo 12/04, connects our Galaxy with the LMC, a relict of dramatic events in the history of our home Galaxy. And the stormy time is not yet over: now the Andromeda Galaxy, another of the Milky Way neighbours in the Local Group of Galaxies, is approaching us. Still at a distance of over 2 million light-years, calculations predict that it will collide with our galaxy in about 6,000 million years!

Original Source: ESO News Release