|SCIENCE TRIBUNE||Thursday, June 7, 2001, Chandigarh, India|
Best-ever eye in the sky
Materials for future IT
NEW PRODUCTS & DISCOVERIES
Unlocking the cosmic secrets
ASTROPHYSICISTS are of view that about 95% of the stars that have taken birth since the universe came into being have been spotted out. And this implies that remaining 5 per cent of the stars still to be detected remain hidden in what is called as "cosmic dark age". One most striking recent breakthrough is the discovery made by astrophysicists in Britain that quasars, the extraordinary superstar that shines more radiantly than any other object in the universe, are essentially powered by the black holes, the universal vacuum cleaners that swallows up everything coming in their way.
Analysis of the data provided by the deep field observation system on board the Hubble Space Telescope (HST), hailed as a supersensitive window on the universe, has thrown fresh light on the early universe. Clearly and apparently HST has shown that quasars rotate with brightness as a consequence of gas being sucked into massive black holes in the centre of the elliptical galaxies. However, what has puzzled the astrophysicists is why the early universe was not uniformly homogenous.
In yet another stunning discovery, a British scientist has reported that he has found evidence for the existence of an undiscovered planet orbiting the sun in the outermost reaches of the solar system. As things stand now, the planet has been described as larger than the Jupiter, the biggest of the nine planets. According to Dr John Murray, a planetary scientist at the Open University, despite its massive size, astronomers could not spot out the planet earlier for the simple reason that it reflects hardly any light. Dr Murray estimates that planet’s position is roughly 33,000 times further away from the sun than the earth.
On the other hand two other Great
Britain based researchers have discovered a new narrow ring of around
1,000 asteroids left over from the birth of our solar system 4-5
billion years ago. And for the first time, astronomers have also
detected light emanating from a planet outside our solar system. Uptil
now more than 20 exoplanets, as the planets circling stars other than
our own sun are called, have been spotted out. However, their exact
structural and functional dynamics are far from well understood. The
discovery was made by Andrew Collier Cameron and his associates at the
University of St. Andrews and Alan Penny at the Rutherford Appleton
Lab in Oxfordshire; they detected the faint signal of starlight
reflected from the planet orbiting sun in the constellation of Bootes,
Tau Boo, from the bright spectrum of the star itself. Tau Boo is known
to be located at a distance of 55 light years away. In an interesting
discovery it has been found that Tau Boo’s planet orbits 20 times
closer to the star than earth orbits the sun.
Best-ever eye in the sky
BY providing the best-ever X-ray images of the distant stars, supernovae, galaxies and quasars, Chandra X-ray observatory is truly leading the way in astrophysics and cosmological studies. Chandra’s revelations have provided crucial information about the mysteries of white dwarfs, neutron stars and black holes — the end products of the stellar evolution. Chandra’s observations are expected to advance our understanding of the evolution of the universe and its constituents.
Chandra X-ray Observatory (CXO), named after the Indian-born Nobel Laureate S. Chandrasekhar, was launched on July 23, 1999, from Columbia space shuttle by NASA. CXO is 13.8 metres long. Its mass is about 4500 kg. Its solar arrays have a wingspan of 19.5 metres. It is placed in an elliptical orbit around the earth, with its perigee of 10,000 km and an apogee of 140,00 km. Thus during its revolution around the earth CXO reaches one-third of the distance to moon.
CXO is designed to study X-ray emission from all types of astronomical objects faint normal stars in our galaxy to bright and distant quasars. To this end, it is carrying a large X-ray telescope, which is the heart of the Chandra observatory. CXO opened its X-ray eyes on August 13, 1999. It started to send spectacular images of X-ray emitting objects on August 26, 1999. These images and their spectral contents have already led to a string of spectacular discoveries.
The official first image from Chandra is of a 320-year-old supernova remnant, Cas-A in the constellation of Cassiopeia. This picture is remarkable for two important discoveries — detection of a point source at the geometrical centre of the exploded star and the distribution of spectral features across it. The point source emission could be either from hot spots on the neutron star surface or a black hole. Longer observations with Chandra in future are expected to clear this mystery.
Another sensational picture taken by Chandra is that of Crab Nebula. It is the remnant of a star explosion that occurred in 1054 AD. Crab Nebula is located 6000 light years away from us in the constellation of Taurus. The centre of the Crab Nebula contains a rapidly rotating neutron star or a pulsar that is pumping enormous amounts of energy into the nebula. Chandra’s X-ray image provides significant clues to the working of this mighty cosmic generator. X-ray jets coming out of the Nebula can be traced all the way into the neutron star.
CXO has sent equally dramatic pictures of many other supernova remnants, present in our neighbouring galaxies such as the Small Magellanic Cloud and the Large Magellanic Cloud. Chandra has created history by detecting X-rays from new explosions of stars going on in other galaxies. During November, 1999, Chandra captured a rare glimpse of X-ray from the early phases of a supernova SNI 1999em. The supernova was detected in spiral galaxy NGC 1637, which is 25 million light years from earth. An X-ray source in the centre of the galaxy is also detected.
The clusters of galaxies provide crucial clues for understanding the origin and fate of the universe. One such cluster is Hydra A, which is 840 million light years from the earth. The X-ray image of Hydra A displays for the first time long snake-like strands of 35 million degree hot gas extending away from the centre of the cluster. The X-ray image also reveals a bright wedge of multimillion-degree hot gas pushing into the heart of the cluster.
Chandra has also observed one of the most distant clusters known as 3C295. The cluster is at a distance of 5 billion light years from us. Chandra has discovered that X-ray emission from the central galaxy of the cluster is far more complex than previously known. X-ray observations indicate that an awesome explosion had occurred about a million years ago in the centre of the galaxy. The explosion wracked the 3C295. CXO observations suggest that the explosion is related to an excess of matter falling into the massive black hole.
Quasars are compact and intense sources of X-rays or visible light. These are very distant and highly energetic objects. PKS 0637-752 is a quasar that is 6 billion light years away from us. It radiates with the power of 10 trillion suns. Its X-ray image, taken with CXO, reveals a powerful X-ray jet that is probably due to a beam of extremely high-energy particles. The X-ray jet has blasted outward from the quasar for a distance of at least 200,000 light years. Chandra observations combined with radio observations are likely to provide insight into this important cosmic energy conversion process.
Capella is a binary star system of two sun-like stars. The stars are orbiting around each other every 104 days. Capella is at a distance of about 40 light years from earth. The X-ray spectrum of Capella as taken by Chandra is of very high quality. The spectrum is expected to provide us with key information such as densities, temperatures and chemical composition etc about the outer atmospheres (coronae) of sun-like stars.
CXO is expected to make a big impact
on cosmology. It is likely to find new gravitational lenses, distant
quasars at red shifts greater than 5 and distant clusters of galaxies
at red shifts grater than 1. It might help us to solve the puzzle
about the origin of cosmic X-ray background — one of the most
outstanding problems in X-ray astronomy.
Materials for future IT
PRESENT day information technology is based on semiconductor materials, such as silicon, and on magnetic materials, mainly iron based compounds. Information processing and computations are carried out through semiconductor based solid in devices made of magnetic materials such as high density compact discs and hard disks. Direct communication is established between the magnetic memory devices and the semiconductor processing units. Semiconductor materials and magnetic materials certainly form two most powerful pillars of information technology of today.
It has been the endeavour of scientists and technologists involved in research and development in information technology to come up with material that have dual characteristics of both the semiconductor as well as of the magnetic materials. Obviously, with such materials information processing and computations and information storing can be done on a single device which would eliminate and information storing can be done on a single device which would eliminate the intermediate step of the retrieval from and storage of information on separate magnetic devices. This should clearly give rise to computers that are simple in design, less cumbersome in operation, must faster and at the same time which can be fabricated at low cost. These dream materials are magnetic semiconductors which can perform the dual task of information processing and information storage. With integrated circuits fabricated on a magnetic semiconductor computations and information storage facilities would be located within the single device and information processing would be straightforward and much quicker. By integrating information storage and information processing, a new and broader functionality would emerge that does not exist separately in a magnetic material or a semiconductor. It is not difficult to visualise that with the synthetic material or a semiconductor. It is not difficult to visualise that with the synthesis of the two types of material behaviour the sum total of the advantages are going to be more than the simple sum of advantage of its parts.
Recent developments in Japan in the field of magnetic semiconductors are very encouraging and have raised the hopes for their use in information technology in the near future. Earlier work on magnetic semiconductors was done mainly on semiconductor material gallium arsenide into which magnetic atoms manganese have been added. This material is called gallium manganese arsenide and has the desired dual characteristics. But it has higher value of electrical conductivity which makes it unsuitable in solid state devices fabrication. When the conductivity is reduced in this material by using thinner samples, magnetic behaviour disappears altogether leaving it just like an ordinary semiconductor.
Now, researches in Japan have found another material, indium manganese arsenide, which has the dual characteristics of magnetic and semiconductor materials but does not suffer from the shortcomings of the other material mentioned above. In addition to having a suitable value of electrical conductivity needed for its use in device applications, the magnetic behaviour in the new material can be varied by controlling its electrical conductivity. Thus the material indium manganese arsenide can be made magnetic or nonmagnetic by controlling its electrical conductivity which is accomplished by the application of an electric field. Thus in the new magnetic semiconductor material variation in magnetic behaviour (needed for its use in information processing) and variation in magnetic behaviour (required for information storage) can be accomplished by the variation of charge carrier concentration by the applications of an electric field. This key feature of the new material makes it suitable for the new devices of information technology of the future.
The newly emergent behaviour of the novel
magnetic semiconductor material is quite interesting and promising. It shall
take a few years of further research to make use of this and other related
materials in practical devices. A number of teething troubles have to be
overcome before the full potential of these materials can be made use of in
commercially viable devices. But the newly discovered magnetic semiconductor
material have opened up the field of magneto-electronics where magnetic
behaviour can be controlled by using well established electronic techniques.
Future of information technology has become brighter because of the new
development in magnetic semiconductors. Magnetic semiconductors shall yield
information technology devices that have capabilities much in excess of the
devices fabricated by using semiconductors and magnetic materials separately.
Six-million-year old apeman
PALEONTOGISTS claim to have found the remains of a six-million-year-old apeman, a finding that they said destroyed a cherished version of human evolution.
Teeth, a finger bone, a femur and jaw and arm fragments unearthed in Kenya’s Rift Valley suggest that homindis the size of chimpanzees were modern man’s distant ancestors, they said. The remains are described as the earliest known two-legged hominid.
They have been dubbed "Millennium Ancestor" by the finders, from the College de France in Paris; France’s National Museum of National History and National Centre for Scientific Research (CNRS) and the Community Museums of Kenya.
If confirmed, the discovery means that "Lucy — the famous skeleton found in Ethiopia which is believed by many anthropologists to be the ancestor of Homo sapiens — was a dead branch on the human family tree.
Millennium Ancestor is three million
years older than Lucy and, while displaying ape-like and human-like
characteristics, "is more human-like" than anything
suggested by Lucy’s family, the australopithecines, the team said. AFP
Rapid renewable energy
THE use of fast-growing grasses as a source of renewable energy is being evaluated by the Institute of Arable Crops Research (IACR) in UK.
Dudley Christian, incharge of Institute’s biomass energy crops programme, said that research had already provided new ideas to replace fossil fuels, reduce carbon dioxide emissions and increase biodiversity in UK farming, a report in British Commercial News said.
He said that IACR research showed that biomass energy crops must have rapid growth and high yield of dry matter preferably with low moisture content.
Switch, Miscanthus, and Reed canary grasses were sowed in recent
trials. Harvested in winter, the grass is allowed to dry and then
burned to produce electricity in two biomass power stations that are
being constructed. PTI
NEW PRODUCTS & DISCOVERIES
THERE may be more planets like earth, findings by astronomers in US and Canada suggest.
Such hopes were raised when researchers found a large amount of the rocky material the planets would be made of around stars like the Sun.
The usual techniques for tracking down "extrasolar" planets rely on detecting tiny changes in a star’s motion caused by the gravitational tug of an orbiting planet. However, since stars are big and difficult to budge, this technique only works if the planet is a giant like Jupiter.
The team, led by Norman Murray of University of Toronto, reasoned that if rocky asteroids — the building blocks of earth-like planets — were orbiting a sun-like star, some would inevitably rain down on the star itself. Many of the asteroids that orbit between Mars and Jupiter have suffered such a fate.
A team member Brain Chaboyer of Dartmouth College in New Hampshire and his colleagues examined the spectra of 642 nearby Sun-like stars for signs of iron, a common constituent of rocky planets. They believed any iron sucked up by a star would get stuck in the star’s outer "mixing" layer. Since this layer generally accounts for only a few per cent of the star’s mass, even a small amount of iron ‘pollution’ should show up in the spectrum.
But the team had to find a way of distinguishing between iron from asteroids and any iron the star was born with. In a paper, submitted to Astrophysical Journal, they said that because sun-like stars of low mass have thicker mixing layers than those of high mass, any collected iron will be more diluted in low mass stars and the spectral signature due to iron will be weaker. If the star’s mixing layer were thin, then the signature of iron would be stronger. This was exactly the pattern found. PTI
New proof of life on Mars
New elements examined on the Martian ALH-84001 meteorite indicate that at one point life existed on the red planet, NASA said in a study which appeared in the journal Proceedings of the National Academy of Sciences.
"The chains we discovered are of biological origin," said Imre Friedmann, a researcher at NASA’s Ames Research Center in California.
Scientists observed magnetite crystals, an iron oxide, strung in chains like a "string of pearls," which they say are formed only by one-living organisms.
"Such a chain of magnets outside an organism would immediately collapse into a clump due to magnetic forces," Friedmann said.
The researchers said the chains, probably formed inside organic material, served as "compasses" for their host organisms themselves decayed. PTI
Magnets to draw out cells
An advanced technique developed for treating certain forms of cancer has found some success. London-based Dr John Kemshead led a team of doctors to discover a new technique of treatment that uses magnets to "draw out" harmful cancer cells.
Usually, in some kinds of cancer treatment, bone marrow is extracted from the patient’s hip who is then given conventional drug and radiotherapy treatment. But the marrow, when it is infused back to allow for re-growth of essential blood components, may contain tumour cells that might grow again.
In the new system the "harvested" marrow is treated with specially cloned anti-bodies then recognised and attach themselves to the cancer cells in the marrow which is then passed across a series of magnets to "catch" the tumourous cells, leaving the healthy marrow to be stored in liquid nitrogen before it is returned to the patient.
1. This US scientist discovered heavy hydrogen (deuterium) which paved the way for isolation of more isotopes of elements. Name this winner of the 1934 Nobel Prize in Chemistry who also did active research in the fields of geochemistry and planetary science.
2. Physicists have recently developed a new class of composite materials which bend electromagnetic radiation in a direction opposite to that predicted by the well-known Snell’s law in optics. What basic inference can you draw about such materials?
3. To treat cancerous tumours in various parts of the body with a higher and more concentrated dose of radiation, without affecting the surrounding organs and tissues, doctors have evolved a new method called IMAT. What does IMAT stand for?
4. Some gemstones display their characteristic internal colours resulting from the interference of light rays within the stone. What is this property called?
5. Which kangaroo is the largest, fastest and the longest jumper on the ground among all the kangaroos?
6. In a computer network, the electrical pulses produced by computers cannot pass through a telephone system. So an electronic device is used for sending and receiving such signals. Which is this device?
7. This instrument consists of a tube containing two mirrors inclined to each other and two small plates that hold pieces of coloured glass. On rotating the tube, coloured patterns are seen. Which is this instrument? What is its basic principle? Who invented it?
8. This chemical is a big environmental hazard but it improves male sexuality. Can you name it?
9. What is the process called by which a three-dimensional image is formed on a film or plate by means of interference between two parts of a split laser beam?
10. Medical graduates take an oath to serve the humanity with selfless duty and dedication and follow a certain code of behaviour and practice. In whose name is this oath taken?
1. Harold Clayton Urey 2. Such
materials have a "negative" refractive index 3. Intensity
Modulated Arc Therapy 4. Opalescence 5. The Giant Red kangaroo 6.
Modem 7. Kaleidoscope; principle of multiple reflections; Scottish Sir
David Brewster in 1817 8. Nitric oxide 9. Holography 10. Greek