Saturday, September 30, 2006

Trick of The Light

Orchid by R Bolance Cordoba, Spain. ENLARGE Image

There is beauty in Nature, beauty mighty fine
There is beauty in Nature, mighty fine design
There is beauty in Nature, here frozen in time
There is beauty in Nature, subtle and sublime
There is beauty in Nature, in its flower design
There is beauty in Nature, here thru time line
There is beauty in Nature, elements do combine
There is beauty in Nature, the design not mine
Famous Quotes:
Change your thoughts and you change your world. NV Peale
The future has a way of arriving unannounced. George Will

Friday, September 29, 2006

Really Big Stars

Artist illustration of
massive star formation.
Image credit: NRAO
Click to enlarge

Astronomers think they’ve got a handle on how Sun-sized stars come together. But the formation of the largest stars - more than 10 times the mass of the Sun - still puzzle astronomers. New observations on a 20 solar mass star have revealed that these giant stars maintain a torus of material around themselves. They can continuously feed from this “doughnut” of material, while powerful jets of radiation pour from their poles. The material can continue gathering onto the star while avoiding this radiation, which would normally blast it back into space.

Astronomers using the National Science Foundation’s Very Large Array (VLA) radio telescope have discovered key evidence that may help them figure out how very massive stars can form.
“We think we know how stars like the Sun are formed, but there are major problems in determining how a star 10 times more massive than the Sun can accumulate that much mass.

The new observations with the VLA have provided important clues to resolving that mystery,” said Maria Teresa Beltran, of the University of Barcelona in Spain.
Beltran and other astronomers from Italy and Hawaii studied a young, massive star called G24 A1 about 25,000 light-years from Earth. This object is about 20 times more massive than the Sun. The scientists reported their findings in the September 28 issue of the journal Nature.
Stars form when giant interstellar clouds of gas and dust collapse gravitationally, compacting the material into what becomes the star. While astronomers believe they understand this process reasonably well for smaller stars, the theoretical framework ran into a hitch with larger stars.

“When a star gets up to about eight times the mass of the Sun, it pours out enough light and other radiation to stop the further infall of material,” Beltran explained. “We know there are many stars bigger than that, so the question is, how do they get that much mass?”
One idea is that infalling matter forms a disk whirling around the star. With most of the radiation escaping without hitting the disk, material can continue to fall into the star from the disk. According to this model, some material will be flung outward along the rotation axis of the disk into powerful outflows.
“If this model is correct, there should be material falling inward, rushing outward and rotating around the star all at the same time,” Beltran said. “In fact, that’s exactly what we saw in G24 A1. It’s the first time all three types of motion have been seen in a single young massive star,” she added.

The scientists traced motions in gas around the young star by studying radio waves emitted by ammonia molecules at a frequency near 23 GHz. The Doppler shift in the frequency of the radio waves gave them the information on the motions of the gas. This technique allowed them to detect gas falling inward toward a large “doughnut,” or torus, surrounding the disk presumed to be orbiting the young star.
“Our detection of gas falling inward toward the star is an important milestone,” Beltran said.

The infall of the gas is consistent with the idea of material accreting onto the star in a non-spherical manner, such as in a disk. This supports that idea, which is one of several proposed ways for massive stars to accumulate their great bulk. Others include collisions of smaller stars.
“Our findings suggest that the disk model is a plausible way to make stars up to 20 times the mass of the Sun. We’ll continue to study G24 A1 and other objects to improve our understanding,” Beltran said.

Beltran worked with Riccardo Cesaroni and Leonardo Testi of the Astrophysical Observatory of Arcetri of INAF in Firenze, Italy, Claudio Codella and Luca Olmi of the Institute of Radioastronomy of INAF in Firenze, Italy, and Ray Furuya of the Japanese Subaru Telescope in Hawaii.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Original Source: NRAO News Release

Stars being born
in the outer

reaches of space

PPARC akari

Company detects a big opportunity
With PPARC funding, British company e2v has developed sensors to help astronomers see deeper into space. This has made it a world leader in fields as diverse as space science, surveillance, defence and medicine. If you’re doing basic scientific research, then one thing’s certain – you’ll always be trying to push limits and explore further than before. Take astronomy, for example. To explore the outer reaches of the universe, you need to detect tiny amounts of light, X-rays and other forms of radiation. And the more sensitive and accurate your detectors, the more you’ll be able to see. Staring into space British company e2v technologies specialises in the design and manufacture of highly sensitive detectors. It first started working on charge-coupled devices in1975. These are circuits that generate electronic signals based on the amounts of light or other radiation they receive. By using regular arrays of sensors, CCDs allow you to take digital images. And, as every budding digital photographer knows, the more sensors – or pixels – a CCD offers, the more detail you can see in your picture. One of the earliest uses of CCDs, however, was in astronomy. Although e2v’s first component only had 220,000 pixels – a trifle compared to today’s digital cameras – astronomers quickly spotted its potential. The devices were quickly put to work on PPARC’s research programmes, but scientists soon wanted more. To create much larger and more sensitive CCD arrays, e2v found a way to ‘stitch’ together the components made on the same silicon wafer. But that was just the start. As a result of e2v’s later work, pictures of the galaxies are now much clearer. Scientists can also see ‘fainter’ images and detect other types of radiation, such as X-rays and ultraviolet light. Our understanding of the universe and how it works has improved enormously.

About e2v
e2v technologies is a leading supplier of high-power electronic components and state-of-the-art sensors. In 2006, it won a Queen’s Award for Enterprise for its innovative L3Vision™ sensors and cameras. The company employs 1,200 people in the UK, where its production facilities are based. Seventy two percent of what it makes is exported. Sales totalled £112 million in the year to March 31 2006. A third of these revenues come from applications related to PPARC.

The Particle Physics and Astronomy Research Council (PPARC) funds research in four broad areas of science: particle physics, astronomy, cosmology and space science. By making it possible for British scientists to explore fundamental questions about the origin of the universe and the structure of matter, it generates ideas and discoveries that have a much broader impact on everyday lives. The UK economy also benefits as ideas turn into innovative new companies and businesses exploit the world-leading skills they create as they meet PPARC’s challenge.

To find out more, visit
The Particle Physics and Astronomy Research Council
Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1SZ, UK
Famous Quotes
Life must be understood backwards; but... it must be lived forward.
Soren Kierkegaard

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Thursday, September 28, 2006

Closer look at Earth

Van Allen Belts: This data-based visualization shows the Van Allen Belts pulsing from solar particles over ten days. The gap that appears toward the end shows a cleared-out safe zone for satellites. The red ring represents the orbit of the IMAGE satellite, which dips into the safe zone every few days.
(Credit: NASA/Tom Bridgman)

Space Scientists Uncover Causes Of Gap In Van Allen Belts
A team of British and US scientists have discovered that the gap in the Van Allen radiation belts is formed by natural wave turbulence in space, not by lightning. The discovery settles years of controversy among space scientists about the mechanisms responsible for causing the gap and has important implications for space weather forecasting

High above the Earth's atmosphere, energetic charged particles are trapped in the Earth's magnetic field where they form the Van Allen radiation belts. Energetic electrons, travelling close to the speed of light, occupy two doughnut shaped zones, usually separated by a gap known as the slot region.

The underlying mechanism that clears the slot region of electrons has been the subject of intense scientific debate. Now, based on analysis of wave data collected over 13 months by the CRRES satellite, Dr Nigel Meredith of British Antarctic Survey and colleagues from BAS, the University of California, Los Angeles and the University of Iowa, believe that the gap is most likely formed by natural wave turbulence in space, rather than by lightning as the alternative theory suggests. Their results are published in the Journal of Geophysical Research this week.

According to lead author, Dr Nigel Meredith:
"Last year NASA scientists suggested that lightning-generated radio waves leaking out into space are responsible for the gap between the two belts by dumping particles into the atmosphere. Since lightning occurs far more often over land than water, waves in space should also occur more over land. However, after analysing satellite data we found that there is no land-ocean variation at frequencies less than 1 kiloHertz where the waves are most intense. Instead, wave activity increases during geomagnetic disturbances driven by the Sun, suggesting that natural wave turbulence is responsible for the gap."

"The results are important, because a better understanding of the radiation belts will help modellers forecast space weather more accurately, helping to protect both astronauts and satellites from radiation hazards."

Van Allen radiation belts
The Van Allen radiation belts were the foremost discovery of the space age after being detected by the first US satellite Explorer I, which was launched during the International Geophysical Year of 1957-58. They are composed of energetic charged particles trapped inside the Earth's magnetic field, which surrounds the Earth like a ring doughnut. Energetic electrons in the Earth's Van Allen radiation belts occupy two distinct regions. The inner zone, which typically extends from altitudes of 200 km to 7000 km in the equatorial plane, is relatively stable. In contrast, the outer zone, which typically lies between 13,000 km and 40,000 km in the equatorial plane, is highly dynamic. The gap between the two zones, known as the slot region, is usually devoid of energetic electrons. However, the slot can fill during strong magnetic storms, such as witnessed during the so-called Halloween storm in 2003. Particles in the slot are subsequently lost, following interactions with the radio waves, on a time-scale of days.

Combined Release and Radiation Effects Satellite
The Combined Release and Radiation Effects Satellite (CRRES) was a joint NASA and U.S. Department of Defense mission to study the near Earth space environment and the effects of the Earth's radiation environment on microelectronic components. The satellite was launched on 25 July 1990 and operated in a highly elliptical geosynchronous transfer orbit with a perigee of 305 km, an apogee of 35,768 km and an inclination of 18o. The orbital period was approximately 10 hours. The satellite swept through the Van Allen radiation belts on average approximately 5 times per day, providing good coverage of this important region for 13 months.

Competing theories
Radio waves in space, known as plasmaspheric hiss, are responsible for the formation of the slot region between the inner and outer radiation belt. While the details of the loss process are well known, the source of these waves has been a matter of intense debate for several decades.

There are two competing theories. One theory maintains that the radio waves are generated locally via natural turbulence in space, arising from particles injected during enhanced magnetic activity driven by the Sun. The other theory suggests that the radio waves, generated by lightning activity on Earth, leak into space and evolve into hiss after multiple reflections in space.
Enhanced fluxes of energetic particles damage spacecraft and are a risk to humans in space. Improved understanding of the weather in space will help protect the satellites and astronauts operating in these regions.
Jupiter, Saturn, Uranus and Neptune all have strong magnetic fields and radiation belts. Improved understanding of the significant processes affecting the Earth's radiation belts will help astronomers to understand the radiation belts of other planets.

British Antarctic Survey is a world leader in research into global issues in an Antarctic context. It is the UK's national operator and is a component of the Natural Environment Research Council. It has an annual budget of around £40 million, runs eight research programmes and operates five research stations, two Royal Research Ships and five aircraft in and around Antarctica.

For more information please visit: British Antartic Survey
Original text Science Daily 27th September 2006
New scientific Challenges And Goals
For European Living Planet Program

The Changing Earth:
ESA's Living Planet
Programme, SP-1304.
Credits: ESA
by Staff Writers Paris, France (ESA)
Space Daily Sep 28, 2006

ESA announces a new science strategy for the future direction of its Living Planet Programme, addressing the continuing need to further our understanding of the Earth System and the impact that human activity is having.

The Changing Earth: New Scientific Challenges for ESA's Living Planet Programme focuses on the most fundamental challenge facing humanity at the beginning of the 21st century - that being global change. As we begin to understand more about the Earth as a system, it is very apparent that human activity is having a profound and negative impact on our environment.

For example, our understanding of carbon dioxide as a greenhouse gas, and the strong link between atmospheric carbon dioxide concentrations and temperature both point to human activity leading to a warmer world, unlike anything seen over the last million years. A better knowledge of the Earth System and the impact that increasing human activity is having is of crucial importance in providing the basis for the management of our environment and our ability to derive sustainable benefit.

Since observing the Earth from space first became possible more than forty years ago, satellite missions have become central to monitoring and learning about how the Earth works. Looking to the future, the new strategy for ESA's Living Planet Programme aims to assess the most important Earth-science questions to be addressed in the years to come. It outlines the observational challenges that these raise, and the contribution that the Agency can make through the programme.

Volker Liebig, ESA Director of Earth Observation stated, "These challenges will guide ESA's efforts in providing essential Earth-observation information to all relevant user communities, in close cooperation with our international partners."

Underpinning the new strategy is a set of ambitious objectives, which include:
Launch a steady flow of missions addressing key issues in Earth science. Provide an infrastructure to allow satellite data to be quickly and efficiently exploited in areas of research and applications. Provide a unique contribution to global Earth Observation capabilities, complementing satellites operated by other agencies and in-situ observing systems. Provide an efficient and cost-effective process whereby science priorities can be rapidly translated into space missions, adequately resourced with associated ground support. Support the development of innovative approaches to instrumentation.

ESA has been dedicated to observing the Earth from space ever since the launch of its first meteorological mission, Meteosat, back in 1977. Following the success of this first mission, the subsequent series of Meteosat satellites developed by ESA and operated by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), together with ERS-1, ERS-2 and Envisat have been providing us with a wealth of invaluable data about the Earth, its climate and changing environment.

Since its conception in the 1990s, ESA's Living Planet Programme has grown to include the family of Earth Explorers, the well-established meteorological missions and the development of the space component for GMES (Global Monitoring for Environment and Security), which is a joint initiative between the European Commission and ESA.

When the Living Planet Programme was first established a new approach to satellite observations for Earth science was formed by focusing on the missions being defined, developed and operated in close cooperation with the science community. By involving the science community right from the beginning in the definition of new missions and introducing a peer-reviewed selection process, it is ensures that a resulting mission is developed efficiently and provides the exact data required by the user.

So far, this approach has resulted in the selection six Earth Explorer missions with another six currently under assessment study. Two Earth Explorer satellites are scheduled for launch next year - GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) and SMOS (Soil Moisture and Ocean Salinity).

While the Earth Explorer series forms the science and research element of the Living Planet Programme the so-called Earth Watch element is designed to facilitate the delivery of Earth-observation data for use in operational services.
Earth Watch includes the well-established meteorological missions with EUMETSAT and new missions focusing on the environment and civil security under GMES. Within this element of the programme, the MetOp mission, which was jointly established by ESA and EUMETSAT, will be Europe's first polar-orbiting weather satellite when it is launched in October.

Although the Earth Watch element of the programme is designed to provide data that underpins operational services, it will also contribute significantly to Earth science, in particular through the collection of longer time series of observations than those provided by research missions. In turn, the Earth Explorers will provide new understanding that paves the way for new operational services. This synergy is also highlighted in the Living Planet Programme's strategy for the coming years.

With the Living Planet Programme's new strategy in place, ESA will build on past success by continuing to play a central role in developing the global capacity to understand planet Earth, predict environmental changes and help mitigate the negative effects of global change on the population.

Cosmic Rays in Atlas by Plato 27th Sept 2006
Gravitational Radiation by Plato 27th Sept 2006
Solar B and Van Allen Belts by Plato 28th Sept 2006
Famous Quotes: We cannot live only for ourselves.
A thousand fibers connect us with our fellow men. Herman Melville

Wednesday, September 27, 2006

Supernova Menagerie

Hubble Space Telescope image of a nearby supernova remnant. Denoted N 63A, the object is the remains of a massive star that exploded, spewing its gaseous layers out into an already turbulent region. (Image Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA); Acknowledgment: Y.-H. Chu and R. M. Williams (UIUC)
ENLARGE Image and more images

Supernova Remnant Menagerie
A new view of violent and chaotic-looking mass of gas has been captured by the Hubble Space Telescope in an image of a nearby supernova remnant. Denoted N 63A, the object is the remains of a massive star that exploded, spewing its gaseous layers out into an already turbulent region.

The supernova remnant N 63A is a member of N 63, a star-forming region in the Large Magellanic Cloud (LMC). Visible from the southern hemisphere, the LMC is an irregular galaxy lying 160,000 light-years from our own Milky Way galaxy. The LMC provides excellent examples of active star formation and supernova remnants, many of which have been studied with Hubble.

Numerous of the stars in the immediate vicinity of N 63A are extremely massive. It is estimated that the 'mother-star', or progenitor, of the supernova that produced the remnant seen here was about 50 times more massive than our own Sun. Such a massive star has strong stellar winds that can clear away the gas around it and form a wind-blown bubble. The supernova that formed N 63A is thought to have exploded inside the central cavity of such a wind-blown bubble, which was itself embedded in a clumpy portion of the LMC's interstellar medium.
Images in the infrared, X-ray, and radio emission of this supernova remnant show the much more expanded bubble that totally encompasses the optical emission seen by Hubble. Odd-shaped mini-clouds or cloudlets that were too dense for the stellar wind to clear away are now engulfed in the bubble interior. The supernova generated a propagating shock wave, that continues to move rapidly through the low-density bubble interior, and shocks these cloudlets, shredding them fiercely.

Supernova remnants have long been thought to set off episodes of star formation when their expanding shock encounters nearby gas. As the Hubble images have illustrated, N 63A is still young and its ruthless shocks destroy the ambient gas clouds, rather than coercing them to collapse and form stars. Data obtained at various wavelengths from other detectors reveal on-going formation of stars at 10-15 light-years from N 63A. In a few million years, the supernova ejecta from N 63A would reach this star-formation site and may be incorporated into the formation of planets around solar-type stars there, much like the early history of the solar system.

The Hubble image of N 63A is a colour representation of data taken in 1997 and 2000 with Hubble's Wide Field Planetary Camera 2. Colour filters were used to sample light emitted by oxygen (shown in blue), hydrogen (shown in green) and sulphur (shown in red).

Source:esa/nasa space telescope
Original text:
Science Daily 8th June 2005
The Case Of The Neutron Star With A Wayward Wake
This composite image was made with wide-field X-ray (blue/Rosat), radio (green/Very Large Array), and optical (red/Digitized Sky Survey) observations of the supernova remnant, IC443. The pullout, also a composite with a Chandra X-ray close-up, shows a neutron star that is spewing out a comet-like wake of high-energy particles as it races through space. Based on an analysis of the swept-back shape of the wake, astronomers deduced that the neutron star known as CXOU J061705.3 222127, or J0617 for short, is moving through the multimillion degree Celsius gas in the remnant. (Chandra X-ray: NASA/CXC/B.Gaensler et al; ROSAT X-ray: NASA/ROSAT/Asaoka & Aschenbach Radio Wide: NRC/DRAO/D.Leahy; Radio Detail: NRAO/VLA Optical: DSS

The Case Of The Neutron Star With A Wayward Wake
A long observation with NASA's Chandra X-ray Observatory revealed important new details of a neutron star that is spewing out a wake of high-energy particles as it races through space. The deduced location of the neutron star on the edge of a supernova remnant, and the peculiar orientation of the neutron star wake, pose mysteries that remain unresolved.

"Like a kite flying in the wind, the behavior of this neutron star and its wake tell us what sort of gas it must be plowing through," said Bryan Gaensler of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author of a paper submitted to The Astrophysical Journal. "Yet we're still not sure how the neutron star got to its present location."

The neutron star, known as CXOU J061705.3+222127, or J0617 for short, appears to lie near the outer edge of an expanding bubble of hot gas associated with the supernova remnant IC 443. Presumably, J0617 was created at the time of the supernova -- approximately 30,000 years ago -- and propelled away from the site of the explosion at about 500,000 miles per hour.
However, the neutron star's wake is oriented almost perpendicularly to the direction expected if the neutron star were moving away from the center of the supernova remnant. This apparent misalignment had previously raised doubts about the association of the speeding neutron star with the supernova remnant.

Gaensler and his colleagues provide strong evidence that J0617 was indeed born in the same explosion that created the supernova remnant. First, the shape of the neutron star's wake indicates it is moving at the predicted pace, which is a little faster than the speed of sound in the remnant's multimillion-degree gas. In contrast, if the neutron star were outside the confines of the remnant, its inferred speed would be a sluggish 20,000 miles per hour. Also, the measured temperature of the neutron star matches that of one born at the same time of the supernova remnant.

What then, could cause the misaligned, or wayward, neutron star wake? The authors speculate that perhaps the doomed progenitor star was moving at a high speed before it exploded, so that the explosion site was not at the observed center of the supernova remnant. Fast moving gusts of gas inside the supernova remnant have further pushed the neutron star's wake out of alignment.

Observations of J0617 in the next 10 years should put this idea to the test. "If the neutron star was born off-center and if the wake is being pushed around by cross-winds, the neutron star should be moving close to vertically, away from the center of the supernova remnant. Now we wait and see," said Gaensler.

Another group, led by Margarita Karovska, also of the Harvard-Smithsonian Center, has concentrated on other, previously unnoticed intriguing features of J0617. At a recent conference on neutron stars in London, England, they announced their findings, which include a thin filament of cooler gas that appears to extend from the neutron star along the long axis of its wake, and a second point-like feature embedded in the X-ray nebula around the neutron star

"There are a number of puzzling observational features associated with this system crying out for longer observations" said Karovska.

Other members of the Gaensler team were S. Chatterjee and P. O. Slane (CfA), E. van der Swaluw (Royal Netherlands Meteorological Institute), F. Camilo (Columbia University), and J. P. Hughes (Rutgers University). Karovska's team included T. Clarke (Naval Research Laboratory), G. Pavlov (Penn State University), and M.C. Weisskopf and V. Zavlin of the Marshall Space Flight Center, Huntsville, Ala. which also manages the Chandra program for NASA's Science Mission Directorate. The Smithsonian Astrophysical Observatory provides science support and controls flight operations from the Chandra X-Ray Centre in Cambridge, Mass.

Original text Science Daily 1st June 2006
Deepest Image Of Exploded Star Uncovers Bipolar Jets
This spectacular image of the supernova remnant Cassiopeia A is the most detailed image ever made of the remains of an exploded star. The one-million-second image shows a bright outer ring (green) ten light years in diameter that marks the location of a shock wave generated by the supernova explosion. A large jet-like structure that protrudes beyond the shock wave can be seen in the upper left. In the accompanying image, specially processed to highlight silicon ions, a counter-jet can be seen on the lower right. (Credit: NASA/CXC/GSFC/U.Hwang et al.)

Deepest Image Of Exploded Star Uncovers Bipolar Jets
The spectacular image of Cassiopeia A released from NASA's Chandra X-ray Observatory has nearly 200 times more data than the "First Light" Chandra image of this object made five years ago. The new image reveals clues that the initial explosion, caused by the collapse of a massive star, was far more complicated than suspected

"Although this young supernova remnant has been intensely studied for years, this deep observation is the most detailed ever made of the remains of an exploded star," said Martin Laming of the Naval Research Laboratory, Washington. Laming is part of a team of scientists led by Una Hwang of NASA's Goddard Space Flight Center, Greenbelt, Md. "It is a gold mine of data that astronomers will be panning through for years to come," he added.

The 1 million-second (about 11.5-day) observation of Cassiopeia A uncovered two large, opposed jet-like structures that extend to about 10 light-years from the center of the remnant. Clouds of iron that have remained nearly pure for the approximately 340 years since the explosion also were detected.

"The presence of the bipolar jets suggests that jets could be more common in relatively normal supernova explosions than supposed by astronomers," said Hwang. A paper by Hwang, Laming and others on the Cassiopeia A observation will appear in an upcoming issue of The Astrophysical Journal Letters.

X-ray spectra show that the jets are rich in silicon atoms and relatively poor in iron atoms. In contrast, fingers of almost-pure iron gas extend in a direction nearly perpendicular to the jets. This iron was produced in the central, hottest regions of the star.
The high silicon and low iron abundances in the jets indicate that massive, matter-dominated jets were not the immediate cause of the explosion, as these should have carried out large quantities of iron from the central regions of the star.

A working hypothesis is that the explosion produced high-speed jets similar to those in hypernovae that produce gamma-ray bursts, but in this case, with much lower energies.The explosion also left a faint neutron star at the center of the remnant.
Unlike the rapidly rotating neutron stars in the Crab Nebula and Vela supernova remnants that are surrounded by dynamic magnetized clouds of electrons, this neutron star is quiet and faint.

Nor has pulsed radiation been detected from it. It may have a very strong magnetic field generated during the explosion that helped to accelerate the jets, and today resembles other strong-field neutron stars (a.k.a. "magnetars") in lacking a wind nebula.

The data for this new Cassiopeia A image were obtained by Chandra's Advanced Charged Coupled Device Imaging Spectrometer (ACIS) instrument during the first half of 2004. Due to its value to the astronomical community, this rich dataset was made available immediately to the public.

NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the NASA Science Mission Directorate, 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.

NASA/Marshall space Flight Centre
Original test: Science Daily 24 August 2004
For additional information and images
Neutron Star Discovered Where A Black Hole Was Expected
The optical image (left) of Westerlund 1 shows a dense cluster of young stars, several with masses of about 40 suns. Some astronomers speculated that repeated collisions between such massive stars in the cluster might have led to formation of an intermediate-mass black hole, more massive than 100 suns. A search of the cluster with Chandra (right) found no evidence for this type of black hole. Instead they found a neutron star (CXO J164710.2-455216), a discovery which may severely limit the range of stellar masses that lead to the formation of stellar black holes. (Credit: NASA/CXC/UCLA/M.Muno et al.)

Neutron Star Discovered Where A Black Hole Was Expected
A very massive star collapsed to form a neutron star and not a black hole as expected, according to new results from NASA's Chandra X-ray Observatory. This discovery shows that nature has a harder time making black holes than previously thought

Scientists found this neutron star, a dense whirling ball of neutrons about 12 miles in diameter, in an extremely young star cluster. Astronomers were able to use well-determined properties of other stars in the cluster to deduce that the progenitor of this neutron star was at least 40 times the mass of the Sun.

"Our discovery shows that some of the most massive stars do not collapse to form black holes as predicted, but instead form neutron stars," said Michael Muno, a UCLA postdoctoral Hubble Fellow and lead author of a paper to be published in The Astrophysical Journal Letters.

When very massive stars make neutron stars and not black holes, they will have a greater influence on the composition of future generations of stars. When the star collapses to form the neutron star, more than 95% of its mass, much of which is metal-rich material from its core, is returned to the space around it.

"This means that enormous amounts of heavy elements are put back into circulation and can form other stars and planets," said J. Simon Clark of the Open University in the United Kingdom.
Astronomers do not completely understand how massive a star must be to form a black hole rather than a neutron star. The most reliable method for estimating the mass of the progenitor star is to show that the neutron star or black hole is a member of a cluster of stars, all of which are close to the same age.
Because more massive stars evolve faster than less massive ones, the mass of a star can be estimated from if its evolutionary stage is known. Neutron stars and black holes are the end stages in the evolution of a star, so their progenitors must have been among the most massive stars in the cluster.
Muno and colleagues discovered a pulsing neutron star in a cluster of stars known as Westerlund 1. This cluster contains a hundred thousand or more stars in a region only 30 light years across, which suggests that all the stars were born in a single episode of star formation. Based on optical properties such as brightness and color some of the normal stars in the cluster are known to have masses of about 40 suns. Since the progenitor of the neutron star has already exploded as a supernova, its mass must have been more than 40 solar masses.
Introductory astronomy courses sometimes teach that stars with more than 25 solar masses become black holes -- a concept that until recently had no observational evidence to test it. However, some theories allow such massive stars to avoid becoming black holes. For example, theoretical calculations by Alexander Heger of the University of Chicago and colleagues indicate that extremely massive stars blow off mass so effectively during their lives that they leave neutron stars when they go supernovae. Assuming that the neutron star in Westerlund 1 is one of these, it raises the question of where the black holes observed in the Milky Way and other galaxies come from.
Other factors, such as the chemical composition of the star, how rapidly it is rotating, or the strength of its magnetic field might dictate whether a massive star leaves behind a neutron star or a black hole. The theory for stars of normal chemical composition leaves a small window of initial masses - between about 25 and somewhat less than 40 solar masses - for the formation of black holes from the evolution of single massive stars. The identification of additional neutron stars or the discovery of black holes in young star clusters should further constrain the masses and properties of neutron star and black hole progenitors.

The work described by Muno was based on two Chandra observations on May 22 and June 18, 2005. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.
Chandra X-Ray Observatory
Original text: Science Daily 3 November 2005
Additional information and images
Swarm Of Black Holes Near The Galactic Center

These images are part of an ongoing Chandra program that monitors a region around the Milky Way's supermassive black hole, Sagittarius A* (Sgr A*). Four bright, variable X-ray sources (circles) were discovered within 3 light years of Sgr A* (the bright source just above Source C). The lower panel illustrates the strong variability of one of these sources. This variability, which is present in all the sources, is indicative of an X-ray binary system where a black hole or neutron star is pulling matter from a nearby companion star. (Credit: NASA/CXC/UCLA/M.Muno et al.)

Chandra Finds Evidence For Swarm Of Black Holes Near The Galactic Center
A swarm of 10,000 or more black holes may be orbiting the Milky Way's supermassive black hole, according to new results from NASA's Chandra X-ray Observatory. This would represent the highest concentration of black holes anywhere in the Galaxy.

These relatively small, stellar-mass black holes, along with neutron stars, appear to have migrated into the Galactic Center over the course of several billion years. Such a dense stellar graveyard has been predicted for years, and this represents the best evidence to date of its existence. The Chandra data may also help astronomers better understand how the supermassive black hole at the center of the Milky Way grows.
The discovery was made as part of Chandra's ongoing program of monitoring the region around Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way. It was announced today by Michael Muno of the University of California, Los Angeles (UCLA) at a meeting of the American Astronomical Society in San Diego, CA.
Among the thousands of X-ray sources detected within 70 light years of Sgr A*, Muno and his colleagues searched for those most likely to be active black holes and neutron stars by selecting only the brightest sources that also exhibited large variations in their X-ray output. These characteristics identify black holes and neutron stars that are in binary star systems and are pulling matter from nearby companion stars. Of the seven sources that met these criteria, four are within three light years of Sgr A*.
"Although the region around Sgr A* is crowded with stars, we expected that there was only a 20 percent chance that we would find even one X-ray binary within a three-light-year radius," said Muno. "The observed high concentration of these sources implies that a huge number of black holes and neutron stars have gathered in the center of the Galaxy."
Mark Morris, also of UCLA and a coauthor on the present work, had predicted a decade ago that a process called dynamical friction would cause stellar black holes to sink toward the center of the Galaxy. Black holes are formed as remnants of the explosions of massive stars and have masses of about 10 suns. As black holes orbit the center of the Galaxy at a distance of several light years, they pull on surrounding stars, which pull back on the black holes.
The net effect is that black holes spiral inward, and the low-mass stars move out. From the estimated number of stars and black holes in the Galactic Center region, dynamical friction is expected to produce a dense swarm of 20,000 black holes within three light years of Sgr A*. A similar effect is at work for neutron stars, but to a lesser extent because they have a lower mass.
Once black holes are concentrated near Sgr A*, they will have numerous close encounters with normal stars there, some of which are in binary star systems. The intense gravity of a black hole can induce an ordinary star to "change partners" and pair up with the black hole while ejecting its companion. This process and a similar one for neutron stars are expected to produce several hundreds of black hole and neutron star binary systems.
"If only one percent of these binary systems are X-ray active each year, they can account for the sources we see," said Eric Pfahl of the University of Virginia in Charlottesville and a coauthor of a paper describing these results that has been submitted to the Astrophysical Journal Letters. "Although the evidence is mostly circumstantial, it makes a strong case for the existence of a large population of neutron stars and stellar-mass black holes within three light-years of the center of our Galaxy."
The black holes and neutron stars in the cluster are expected to gradually be swallowed by the supermassive black hole, Sgr A*, at a rate of about one every million years. At this rate, about 10,000 black holes and neutron stars would have been captured in a few billion years, adding about 3 percent to the mass of the central supermassive black hole, which is currently estimated to contain the mass of 3.7 million suns.
In the meantime, the acceleration of low-mass stars by black holes will eject low-mass stars from the central region. This expulsion will reduce the likelihood that normal stars will be captured by the central supermassive black hole. This may explain why the central regions of some galaxies, including the Milky Way, are fairly quiet even though they contain a supermassive black hole.

The region analyzed in this research near Sgr A* has been observed 16 times between 1999 and 2004 using Chandra's Advanced CCD Imaging Spectrometer (ACIS) instrument. Other members of the research team include Frederick K. Baganoff (Massachusetts Institute of Technology), Niel Brandt (Penn State), Andrea Ghez and Jessica Lu (UCLA).
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate, Washington. The Smithsonian Astrophysical Observatory controls science and flight operations from the
Chandra X-ray Center in Cambridge, Mass.

Original text:
Science Daily 12th January 2005
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Monday, September 25, 2006

Young Galaxies

It's the shape and colour of a futuristic space ship. It holds the promise of drawing more young people into the field of information technology.

The simulator is an entry point for students to learn the latest in 4D- modelling techniques for virtual reality, real-time systems and control, animation tools, user interfaces, and sensory feedback. This technology is finding and driving countless other fields including audio and visual modeling, flight simulation, design prototyping, architectural visualization, animation, and digital image processing.

Hubble Finds Hundreds Of Young Galaxies In Early Universe
Astronomers analyzing two of the deepest views of the cosmos made with NASA's Hubble Space Telescope have uncovered a gold mine of galaxies, more than 500 that existed less than a billion years after the Big Bang. These galaxies thrived when the cosmos was less than 7 percent of its present age of 13.7 billion years. This sample represents the most comprehensive compilation of galaxies in the early universe, researchers said.

The discovery is scientifically invaluable for understanding the origin of galaxies, considering that just a decade ago early galaxy formation was largely uncharted territory. Astronomers had not seen even one galaxy that existed when the universe was a billion years old, so finding 500 in a Hubble survey is a significant leap forward for cosmologists.

The galaxies unveiled by Hubble are smaller than today's giant galaxies and very bluish in color, indicating they are ablaze with star birth. The images appear red because of the galaxies' tremendous distance from Earth. The blue light from their young stars took nearly 13 billion years to arrive at Earth. During the journey, the blue light was shifted to red light due to the expansion of space.

"Finding so many of these dwarf galaxies, but so few bright ones, is evidence for galaxies building up from small pieces -- merging together as predicted by the hierarchical theory of galaxy formation," said astronomer Rychard Bouwens of the University of California, Santa Cruz, who led the Hubble study.

Bouwens and his team spied these galaxies in an analysis of the Hubble Ultra Deep Field (HUDF), completed in 2004, and the Great Observatories Origins Deep Survey (GOODS), made in 2003. The results were presented on August 17 at the 2006 General Assembly of the International Astronomical Union, and will be published in the November 20 issue of the Astrophysical Journal.

Astronomers analyzing two of the deepest views of the cosmos made with NASA's Hubble Space Telescope have uncovered a gold mine of galaxies, more than 500 that existed less than a billion years after the Big Bang. This sample represents the most comprehensive compilation of galaxies in the early universe, researchers said. (Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz)) hubblesite IMAGE Options

The findings also show that these dwarf galaxies were producing stars at a furious rate, about ten times faster than is happening now in nearby galaxies. Astronomers have long debated whether the hottest stars in early star-forming galaxies, such as those in this study, may have provided enough radiation to reheat the cold hydrogen gas that existed between galaxies in the early universe. The gas had been cooling since the Big Bang.

"Seeing all of these starburst galaxies provides evidence that there were enough galaxies 1 billion years after the Big Bang to finish reheating the universe," explained team member Garth Illingworth of the University of California, Santa Cruz. "It highlights a period of fundamental change in the universe, and we are seeing the galaxy population that brought about that change."

In terms of human lifetimes, cosmic events happen very slowly. The evolution of galaxies and stars, for example, occurs over billions of years. Astronomers, therefore, rarely witness dramatic, relatively brief transitions that changed the universe. One such event was the universe's "reheating." The reheating, driven by the galaxies' ultraviolet starlight, transformed the gas between galaxies from a cold, dark hydrogen soup to a hot, transparent plasma over only a few hundred million years. With Hubble's help, astronomers are now beginning to see the kinds of galaxies that brought about the reheating.

Just a few years ago, astronomers did not have the technology to hunt for faraway galaxies in large numbers. The installation of the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope in 2002 allowed astronomers to probe some of the deepest recesses of our universe. Astronomers used the ACS to observe distant galaxies in the HUDF and GOODS surveys.

Another major step in the exploration of the universe's earliest years will occur if Hubble undergoes its next upgrade with the Wide Field Planetary Camera 3 (WFC3). The WFC3's infrared sensitivity will allow it to detect galaxies that are so far away their starlight has been stretched to infrared wavelengths by the expanding universe.

The galaxies uncovered so far promise that many more galaxies at even greater distances are awaiting discovery by the James Webb Space Telescope (JWST), scheduled to launch in 2013. "With JWST, we will probe the dawn of galaxy formation to see the imprint of the first objects to form in the universe," Illingworth said.

The members of the science team are Rychard Bouwens and Garth Illingworth (University of California, Santa Cruz), John Blakeslee (Washington State University), and Marijn Franx (Leiden University).
Source hubblesite Space Telescope Science Institute
Original text
Science Daily releases 21st Sept 2006
Related article universetoday new-kind-of-supernova-discovered
Evolution of Galaxies hubblesite images web print ENLARGE Image
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Our knowledge is a little island in a great ocean of nonknowledge.
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Saturday, September 23, 2006

Kabbalist Wisdom

The Ram courtesy of kristal

Not all tears find their way to the king.
Tears of anger and tears of accussation
against one's fellow
do not come into the king's presence.
But tears of repentance and prayer do,
as well as the tears of those
who ask for relief from their distress.

Gaze with divine intelligence into the works of the kabbalists.
Hence you will discover that which you seek and you will see
that they all cry out in protest against the absence of wisdom.
Famous Quotes
Time is what we want most, but what we use worst. William Penn
Perpetual optimism is a force multiplier. Colin Powell

Thursday, September 21, 2006

Brown Dwarf Stars

This is an artist's concept of the star HD 3651 as it is orbited by a close-in Saturn-mass planetary companion and the distant brown dwarf companion discovered by Spitzer infrared photographs. The Saturn-mass planet was discovered through Doppler observations in 2003. Its orbit is very small, the size of Mercury's, and is highly elliptical. The gravity of the distant brown dwarf companion may be reponsible for the distorted shape of the inner planet's orbit.
(Credit: NASA / JPL-Caltech / T. Pyle (SSC))

First Images Of Brown Dwarf In Planetary System
Scientists using NASA's Spitzer Space Telescope have discovered and directly imaged a small brown dwarf star, 50 times the mass of Jupiter, orbiting with a planet around a Sun-like star. Such an arrangement has never before been seen but might be common, the scientists say, leading to solar systems with distorted planetary orbits.

The discovery concerns a class of the coldest brown dwarfs, called T dwarfs.
Over the last ten years, astronomers have been extremely successful in finding planets close to their host stars using indirect detection methods," said Luhman, an assistant professor in the Penn State Department of Astronomy and Astrophysics. "Because of its infrared capabilities, Spitzer is well suited for directly detecting cool T dwarfs, and perhaps even large planets, in the outer parts of planetary systems."

Luhman's team also discovered a second brown dwarf that is smaller yet, about 20 times the mass of Jupiter, orbiting another star. This smaller object could be the youngest T dwarf known, offering scientists a snapshot of early brown-dwarf development. The two T dwarfs are the first to be imaged by Spitzer. Shortly after these companions were found, Spitzer also discovered a T dwarf that is floating through space by itelf rather than orbiting a star. The team that discovered that T dwarf is led by Daniel Stern at NASA's Jet Propulsion Laboratory.

Brown dwarfs are small stars that are not massive enough to burn hydrogen, like our Sun does. Their cores are not hot enough to trigger such nuclear fusion. As a result, their surface temperature is only a few thousands of degrees when young, cooling considerably to about the temperature of a planet as they age. Consequently, they are dim and hard to identify and, as a result, the first unambiguous identification came only about ten years ago.

The more massive of the two newly discovered T dwarfs is called HD 3651 B, located in the constellation Pisces. This object is in a solar system containing a star slightly less massive than our Sun that is orbited by a planet slightly smaller than Saturn.

The planet's orbit around the Sun-like star is highly elliptical, which had suggested that the gravity of some unseen object farther away from the star was pulling the planet outward. Sure enough, it was a T dwarf. Many extrasolar planets have been discovered with highly elliptical orbits. The Spitzer discovery is the first evidence to support the theory that small companions such as T dwarfs can hide in such solar systems and can cause the orbits of planets to be extreme.

"The orbit of the planet in this system is similar to Mercury's, but the T dwarf has an orbit over ten times larger than Pluto's," said Brian Patten of the Harvard-Smithsonian Center for Astrophysics (CfA), a co-author. "Although HD 3651 B would be just beyond naked-eye visibility to an intrepid astronomer living on this system's planet, the T dwarf makes its presence known through gravity."

The other T dwarf is called HN Peg B in the constellation Pegasus. Whereas most brown dwarfs are billions of years old, HN Peg B is relatively young, only about 300 million years old. The scientists determined its age by carefully studying the companion star, which was formed at the same time from the same gas cloud. The system also contains a previously discovered disk of dust and rocks.

"Detectable debris disks and T dwarf companions are fairly rare, so the presence of both around the same star makes this a particularly exciting star system," said Giovanni Fazio of CfA, a co-author.

The discoveries were made with Spitzer's infrared camera, built primarily at NASA Goddard Space Flight Center in Greenbelt, Maryland. The instrument's principal investigator is Giovanni Fazio. Other team members include Massimo Marengo, Joseph Hora, Richard Ellis, Michael Schuster, Sarah Sonnett, Elaine Winston, and Robert Gutermuth of the CfA; John Stauffer of Caltech; Tom Megeath of the University of Toledo; Dana Backman of the SOFIA/SETI Institute; Tod Henry of Georgia State University; and Michael Werner of NASA Jet Propulsion Laboratory.

The Jet Propulsion Laboratory, in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena.

Source: Kevin Luhman, Penn State Astro
Science Daily press releases 19th Sept 2006

Artist's impression of the SCR 1845-6357 stellar system. The small red star is shown in the background while the newly discovered brown dwarf is at front. (Image courtesy of European Southern Observatory)

The Sun's New Exotic Neighbor: A Very Cool Brown Dwarf
Using the European Southern Observatory's Very Large Telescope in Chile, an international team of researchers discovered a brown dwarf belonging to the 24th closest stellar system to the Sun. Brown dwarfs are intermediate objects that are neither stars nor planets. This object is the third closest brown dwarf to the Earth yet discovered, and one of the coolest, having a temperature of about 750 degrees Centigrade. It orbits a very small star at about 4.5 times the mean distance between the Earth and the Sun. Its mass is estimated to be somewhere between 9 and 65 times the mass of Jupiter.

At a time when astronomers are peering into the most distant Universe, looking at objects as far as 13 billion light-years away, one may think that our close neighbourhood would be very well known. Not so. Astronomers still find new star-like objects in our immediate vicinity. Using ESO's VLT, they just discovered a brown dwarf companion to the red star SCR 1845-6357, the 36th closest star to the Sun.

"This newly found brown dwarf is a valuable object because its distance is well known, allowing us to determine with precision its intrinsic brightness", said team member Markus Kasper (ESO). "Moreover, from its orbital motion, we should be able in a few years to estimate its mass. These properties are vital for understanding the nature of brown dwarfs."
To discover this brown dwarf, the team used the high-contrast adaptive optics NACO

Simultaneous Differential Imager (SDI) on ESO's Very Large Telescope, an instrument specifically developed to search for extrasolar planets. The SDI camera enhances the ability of the VLT and its adaptive optics system to detect faint companions that would normally be lost in the glare of the primary star. In particular, the SDI camera provides additional, often very useful spectral information which can be used to determine a rough temperature for the object without follow-up observations.

Located 12.7 light-years away from us, the newly found object is nevertheless not the closest brown dwarf. This honour goes indeed to the two brown dwarfs surrounding the star Epsilon Indi, located 11.8 light years away.

However, this newly discovered brown dwarf is unique in many aspects. "Besides being extremely close to Earth, this object is a T dwarf - a very cool brown dwarf - and the only such object found as a companion to a low-mass star," said Beth Biller, a graduate student at the University of Arizona and lead author of the paper reporting the discovery. "It is also likely the brightest known object of its temperature because it is so close."

The discovery of this brown dwarf hints that, at least close to the Sun, cool brown dwarfs prefer to be part of a couple with a star or another brown dwarf, rather than wandering alone in the cosmic emptiness. Indeed, of the seven cool brown dwarfs that reside within 20 light years of the Sun, five have a companion.

The work presented is a Letter to the Editor in the Astrophysical Journal:
"Very Nearby to the Sun: A Methane Rich Brown Dwarf"
Source: European Southern Observatory
Science Daily press releases 22nd March 2006

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Tuesday, September 19, 2006

Swift GRB Explorer

The Swift Gamma Ray Burst Explorer
carries three instruments to enable the most detailed observations of gamma ray bursts to date.

Two of these instruments, the X-ray Telescope (XRT) and the UV/Optical Telescope (UVOT) were built by Penn State and collaborators at Leicester University and the Mullard Space Science Laboratory (both in England) and at the Osservatorio Astronomico di Brera (in Italy).

In addition, Penn State is responsible for leading the Education and Public Outreach component of this mission, as well as the Mission Operations Center, which operates the satellite.

The three coaligned instruments are known as the BAT, the XRT, and the UVOT. The XRT and UVOT are X-ray and a UV/optical focusing telescopes respectively which produce sub-arcsecond positions and multiwavelength lightcurves for gamma ray Burst (GRB) afterglows. Broad band afterglow spectroscopy produces redshifts for the majority of GRBs. BAT is a wide Field-Of-View (FOV) coded-aperture gamma ray imager that produces arcminute GRB positions onboard within 10 seconds. The spacecraft executes a rapid autonomous slew that points the focusing telescopes at the BAT position in typically ~ 50s.

The positions and images derived by the various instruments are sent as soon as they are available from the spacecraft via the TDRSS system to the Gamma Ray Coordination Network (GCN). The GCN broadcasts the results to the world via the Internet for rapid response by the world astronomy community for follow up observations by other ground and space based telescopes. At the next satellite pass over Malindi, the more detailed data is sent to the data center where it will be processed for public access within 30 minutes of the pass.

Penn State Swift Guide

Image credit: NASA/GSFC/Swift/Stefan Immler ENLARGE Image

On July 5, 2006, the Swift observatory began observing supernova 2006dm a few days after its explosion. The supernova is the result of the thermonuclear explosion of a white dwarf in the galaxy MCG -01-60-21 which is located some 300 million lightyears from Earth. The galaxy is part of a loose group of galaxies which are gravitationally bound and have passed close to each other in the past. Remnants of such a recent nearby encounter are the faint bridges of stars and gas between the two brightest galaxies of this group, stretching from the upper left to the lower right of the image.

The image was obtained with the Ultraviolet/Optical Telescope (UVOT) onboard Swift in the V, B, and U filters and has been merged from four individual observations obtained between July 5 and 8.
Further reading: swift gsfc nasa gov
Penn State Astrophysics & Astronomy
ICECUBE wisc edu: gallery detector concepts
Famous Quotes: Wisdom begins in wonder. Socrates
Famous Quotes: There is only one success -
to be able to spend your life in your own way. Christopher Morley

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Monday, September 18, 2006

Gamma Ray Bursts

Recent developments
in the study of
Gamma-ray bursts

The Royal Society
6-9 Carlton House Terrace
London SW1Y 5AG

Discussion Meeting: Monday 18 to Wednesday 20 September 2006

Professor Martin Rees PRS, Professor Len Culhane FRS, Professor Keith Mason and Professor Alan Wells
New results from the SWIFT mission and new theoretical studies of gamma ray burst physics are defining the agenda for this meeting.

SWIFT has detected over 140 bursts since its launch in November 2004. It has obtained the first accurate localizations and afterglow detections of short bursts, leading to the discovery that the progenitors are indeed mergers in compact binary systems.
For list of events see here

A Flash in
the Cosmic Pan
18 Sept 2006
Image to left:
Dying stars like
the one inside
this planetary nebula
are a possible source
for gamma-ray bursts.
Credit: NASA

Like galactic fireworks in the night, gamma-ray bursts briefly light up the stellar sky as only the most powerful explosions in the universe can. Yet as magnificent as gamma-ray bursts are, their fleeting nature makes them elusive and difficult to study.

Gamma-ray bursts are incredibly intense releases of gamma radiation. Found at the highest frequency end of the electromagnetic spectrum, gamma radiation is a particularly energetic form of light that can only be generated by the most powerful astronomical events. Scientists suspect that these sporadic explosions may signal the birth of black holes or the death of stars.

The first gamma-ray bursts were detected in 1967 by the U.S. military's Vela satellites. This fleet of satellites was originally designed to monitor nuclear weapons testing and could sense large releases of gamma radiation. While orbiting the Earth, a Vela satellite recorded a burst of concentrated gamma energy from deep space. For the first time, a gamma-ray burst was observed by humans.

Modern, space-based gamma-ray burst research began in earnest with the 1991 launch of the Compton Gamma Ray Observatory aboard Space Shuttle Atlantis. For nine years, the Compton Observatory searched the sky for gamma-ray activity. In those years in orbit, the observatory made a number of discoveries and mapped thousands of gamma-ray bursts.

In 1997, the Italian Space Agency placed the BeppoSAX satellite in orbit and it made a critical discovery by identifying the lingering X-ray "afterglow" produced by erupting gamma-ray bursts. This finding allowed astronomers to look at the bursts in a new light, and paved the way for the design of new spacecraft like Swift.

Today, the pursuit of gamma-ray bursts continues since the launch of the Swift spacecraft. Armed with a trio of telescopes and a network of supporting space-based and ground telescopes, astronomers have managed to set a sophisticated trap that is ready to catch gamma-ray bursts in the act as they light up the night.

NASA mission pages
NASA's John F. Kennedy Space Center


NASA Satellite
2 year Study of
Black Hole Birth

Gamma Ray Bursts

18 Sept 2006

By the end of this day, somewhere in the visible universe a new black hole will have formed. Gamma-ray bursts (GRBs), the most distant and powerful explosions known, are likely the birth cries of these new black holes. NASA's Swift mission is dedicated to studying the gamma-ray burst/black hole connection.

The Swift spacecraft began its mission from Cape Canaveral Air Force Station in 2004, building on nearly 40 years of research and observations. It is fine-tuned to quickly locate these bursts and study them in several different wavelengths before they disappear forever.

Swift is a little satellite with a big appetite, and caps off a 30-year hunt to understand the nature of gamma-ray bursts, flashes of light that burn as brightly as a billion billion suns.

Gamma-ray bursts are fleeting events, lasting only a few milliseconds to a few minutes, never to appear in the same spot again. They occur from our vantage point about once a day. Some bursts appear to be from massive star explosions that form black holes.
Read more: NASA watchtheskies/SWIFT Media

Related Links:
Gamma Ray Detection by Plato
Cosmicopia: An abundance of Cosmic rays from helios nasa gov
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The art of simplicity is a puzzle of complexity. Doug Horton

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Sunday, September 17, 2006

Beyond Sol. EXO Planets

Art Image
of early Earth
Ocean, Moon

cfa image ENLARGE

Astronomers Reveal first Exo Planet ID chart
Boston MA (SPX) Sep 14, 2006

It is only a matter of time before astronomers find an Earth-sized planet orbiting a distant star. When they do, the first questions people will ask are: Is it habitable? And even more importantly, is there life present on it already? For clues to the answers, scientists are looking to their home planet, Earth.
Astronomers Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics (CfA) and Wesley Traub of NASA's Jet Propulsion Laboratory and CfA, propose using Earth's atmospheric history to understand other planets. "Good planets are hard to find," said Kaltenegger. "Our work provides the signposts astronomers will look for when examining truly Earth-like worlds."
Read More ... Harvard-Smithsonian CfA edu press

New Planet
Baffles Astronomers

cfa image ENLARGE
by Staff Writers
Boston MA (SPX) Sep 14, 2006

Using a network of small, automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.
"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at CfA. Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Although stranger than any other extrasolar planet found so far, HAT-P-1 is not alone in its low-density status. The first planet ever found to transit its star, HD 209458b, also is puffed up about 20 percent larger than predicted by theory. HAT-P-1 is 24 percent larger than expected.

"Out of eleven known transiting planets, now not one but two are substantially bigger and lower in density than theory predicts," said co-author Robert Noyes (CfA). "We can't dismiss HD209458b as a fluke. This new discovery suggests something could be missing in our theories of how planets form."

Related Links:
Harvard-Smithsonian Center for Astrophysics

Changing World View philosophical-juggernaut by Plato
Spherical Earth ??? sphere-that-is-not-so-round by Plato

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Saturday, September 16, 2006

Mistery Vessel

Photo courtesy of mischiefangel "For life is a continuum of actions"

Cedar wood vessel
beautifully crafted
not by the hand of man

but created by the forces of Nature
the Sun, the Sea, the Salt, the Air
the light & heat, the tides, the wind

Driftwood shaped by the elements
from stardust & organic minerals
mistery vessel resting on the shore

Quasar9 thinks in the magic lamp a mistery vessel he doeth see
Angel Dust says the mistery vessel a Ship or Sea vessel must be

Perhaps you'd like to tell, what it looks like to you & thee

What is it like to know the secret of the Merkavah?
"It is like having a ladder in one's home
and being able to go up and down at will"

Famous Quotes
Somewhere, something incredible is waiting to be known. Carl Sagan

Friday, September 15, 2006

Eternal Life of Stardust

The Eternal Life
of Stardust
In New
NASA Image
ENLARGE Image IPAC NASA High Resolution
by Staff WritersPasadena CA (SPX) Sep 01, 2006

A new image from NASA's Spitzer Space Telescope is helping astronomers understand how stardust is recycled in galaxies. The cosmic portrait shows the Large Magellanic Cloud, a nearby dwarf galaxy named after Ferdinand Magellan, the seafaring explorer who observed the murky object at night during his fleet's historic journey around Earth.

Now, nearly 500 years after Magellan's voyage, astronomers are studying Spitzer's view of this galaxy to learn more about the circular journey of stardust, from stars to space and back again.
"The Large Magellanic Cloud is like an open book," said Dr. Margaret Meixner of the Space Telescope Science Institute, Baltimore, Md. "We can see the entire lifecycle of matter in a galaxy in this one snapshot." Meixner is lead author of a paper on the findings to appear in the November 2006 issue of the Astronomical Journal.

The vibrant false-color image, a mosaic of approximately 300,000 individual frames, shows a central blue sea of stars amidst lots of colorful, choppy waves of dust.

Space dust is important for making stars, planets and even people. The tiny particles -- flecks of minerals, ices and carbon-rich molecules -- are everywhere in the universe. Developing stars and solar systems are constantly consuming dust, while older stars shed dust back into space, where it will one day provide the ingredients for new generations of stars.

Spitzer, an infrared observatory orbiting the sun, is extremely sensitive to the infrared glow of dust that arises when stars heat it up. The observatory's unprecedented view of the Large Magellanic Cloud offers a unique look at three stops on the eternal ride of dust through a galaxy: in collapsing envelopes around young stars; scattered about in the space between stars; and in expelled shells of material from old stars.

"The Spitzer observations of the Large Magellanic Cloud are giving us the most detailed look yet at how this feedback process works in an entire galaxy," said Meixner. "We can quantify how much dust is being consumed and ejected by stars."

In addition to dust, Spitzer's view reveals nearly one million never-before-seen objects, most of which are stars in the Large Magellanic Cloud. The hidden stars, both young and old, are embedded in layers of dust that block visible starlight but shine in infrared.

The Large Magellanic Cloud is one of a handful of dwarf galaxies that orbit our own Milky Way. It is located near the southern constellation Dorado, about 160,000 light-years from Earth. About one-third of the whole galaxy can be seen in the Spitzer image.

Astronomers believe that approximately six billion years ago, not long before our solar system formed, this dwarf galaxy was shaken up via a close encounter with the Milky Way. The resulting chaos triggered bursts of massive star formation similar to what is thought to occur in more primitive galaxies billions of light-years away. This and other distant-galaxy traits, such as an irregular shape and low abundance of metals, make the Large Magellanic Cloud the perfect nearby target for studying the faraway universe.

This research is part of a Spitzer Legacy program called Surveying the Agents of a Galaxy's Evolution, also known as Sage. The international Sage team includes more than 50 astronomers spread over the globe from Japan to the United States. The main data centers are located at: the Space Telescope Science Institute, Baltimore, Md., led by Meixner; University of Arizona, Tucson, led by Gordon; and University of Wisconsin, Madison, led by Dr. Barbara Whitney.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera and multiband imaging photometer captured the new image. The camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. Its principal investigator is Dr. Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. The photometer was built by Ball Aerospace Corporation, Boulder, Colo.; the University of Arizona; and Boeing North American, Canoga Park, Calif. Its principal investigator is Dr. George Rieke of the University of Arizona, Tucson.

Original Text: Space Daily 01 Sept: The Eternal Life Of Stardust Portrayed

General Relativity Survives Gruelling Pulsar Test:
Einstein At Least 99.95 Percent Right
An international research team led by Prof. Michael Kramer of the University of Manchester's Jodrell Bank Observatory, UK, has used three years of observations of the "double pulsar", a unique pair of natural stellar clocks which they discovered in 2003, to prove that Einstein's theory of general relativity - the theory of gravity that displaced Newton's - is correct to within a staggering 0.05%. Their results are published on the14th September in the journal Science and are based on measurements of an effect called the Shapiro Delay.

Here's a depiction of the double pulsar system currently being tracked by the international team of radio astronomers who discovered it, including Dr. Duncan Lorimer and Dr. Maura McLaughlin of West Virginia University.

The pulsars are the remnants of two massive stars that burned out by way of supernova explosions. They measure just 12 miles across, but each weighs more than our own Sun. Note the "bend" in the space-time fabric from the sheer mass of the two bodies. Image courtesy of West Virginia University

The double pulsar system, PSR J0737-3039A and B, is 2000 light-years away in the direction of the constellation Puppis. It consists of two massive, highly compact neutron stars, each weighing more than our own Sun but only about 20 km across, orbiting each other every 2.4 hours at speeds of a million kilometres per hour. Separated by a distance of just a million kilometres, both neutron stars emit lighthouse-like beams of radio waves that are seen as radio "pulses" every time the beams sweep past the Earth. It is the only known system of two detectable radio pulsars orbiting each other. Due to the large masses of the system, they provide an ideal opportunity to test aspects of General Relativity:

Gravitational redshift: the time dilation causes the pulse rate from one pulsar to slow when near to the other, and vice versa.
Shapiro delay: The pulses from one pulsar when passing close to the other are delayed by the curvature of space-time. Observations provide two tests of General Relativity using different parameters.
Gravitational radiation and orbital decay: The two co-rotating neutron stars lose energy due to the radiation of gravitational waves. This results in a gradual spiralling in of the two stars towards each other until they will eventually coalesce into one body.

By precisely measuring the variations in pulse arrival times using three of the world's largest radio telescopes, the Lovell Telescope at Jodrell Bank, the Parkes radio-telescope in Australia, and the Robert C. Byrd Green Bank Telescope in West Virginia, USA, the researchers found the movement of the stars to exactly follow Einstein's predictions. "This is the most stringent test ever made of General Relativity in the presence of very strong gravitational fields -- only black holes show stronger gravitational effects, but they are obviously much more difficult to observe", says Kramer.

Since both pulsars are visible as radio emitting clocks of exceptional accuracy, it is possible to measure their distances from their common centre of gravity. "As in a balanced see-saw, the heavier pulsar is closer to the centre of mass, or pivot point, than the lighter one and so allows us to calculate the ratio of the two masses", explains co-author Ingrid Stairs, an assistant professor at the University of British Columbia in Vancouver, Canada. "What's important is that this mass ratio is independent of the theory of gravity, and so tightens the constraints on General Relativity and any alternative gravitational theories." adds Maura McLaughlin, an assistant professor at West Virginia University in Morgantown, WV, USA.

Though all the independent tests available in the double pulsar system agree with Einstein's theory, the one that gives the most precise result is the time delay, known as the Shapiro Delay, which the signals suffer as they pass through the curved space-time surrounding the two neutron stars. It is close to 90 millionths of a second and the ratio of the observed and predicted values is 1.0001 +/- 0.0005 - a precision of 0.05%.

A number of other relativistic effects predicted by Einstein can also be observed. "We see that, due to its mass, the fabric of space-time around a pulsar is curved. We also see that the pulsar clock runs slower when it is deeper in the gravitational field of its massive companion, an effect known as "time dilation".

A key result of the observations is that the pulsar's separation is seen to be shrinking by 7mm/day. Einstein's theory predicts that the double pulsar system should be emitting gravitational waves - ripples in space-time that spread out across the Universe at the speed of light. "These waves have yet to be directly detected ", points out team member Prof. Dick Manchester from the Australia Telescope National Facility, "but, as a result, the double pulsar system should lose energy causing the two neutron stars to spiral in towards each other by precisely the amount that we have observed - thus our observations give an indirect proof of the existence of gravitational waves."

Michael Kramer concludes; "The double pulsar is really quite an amazing system. It not only tells us a lot about general relativity, but it is a superb probe of the extreme physics of super-dense matter and strong magnetic fields but is also helping us to understand the complex mechanisms that generate the pulsar's radio beacons." He concludes; "We have only just begun to exploit its potential!"

Science Daily releases: 14th Sept 2006 Source: PPARC
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