Scientists reveal secret of levitation

LONDON (AFP) - Scientists have discovered a ground-breaking way of levitating ultra small objects, which may revolutionise the design of micro-machines, a new report says. Physicists said they can create "incredible levitation effects" by manipulating so-called Casimir force, which normally causes objects to stick together by quantum force.
The phenomenon could be used to improve the performances of everyday devices ranging from car airbags to computer chips, say Professor Ulf Leonhardt and Dr Thomas Philbin from Saint Andrews University.
Casimir force -- discovered in 1948 and first measured in 1997 -- can be seen in a gecko's ability to stick to a surface with just one toe.
Now the British scientists say they can reverse the Casimir force to cause an object to repel rather than attract another in a vacuum.
"The Casimir force is the ultimate cause of friction in the nano world, in particular in some micro-electromechanical systems," said Leonhardt, writing in the August issue of New Journal of Physics.
"Micro or nano machines could run smoother and with less or no friction at all if one can manipulate the force," he added.
And he added: "In order to reduce friction in the nanoworld, turning nature's stickiness into repulsion could be the ultimate remedy. Instead of sticking together, parts of micromachinery would levitate."
Leonhardt stressed that the practise is possible only for micro-objects.
But he underlined that, although in principle it may one day be possible to levitate humans, that day is a long way off.
"At the moment, in practice it is only going to be possible for micro-objects with the current technology, since this quantum force is small and acts only at short ranges," he said.
"For now, human levitation remains the subject of cartoons, fairytales and tales of the paranormal."
Their research was to be published in the New Journal of Physics.

source: AFP and yahoo news

srini

Water vapor on an exoplanet

Water vapor on an exoplanet

Using the Spitzer Space Telescope, astronomers find signs of water on a "hot Jupiter."

Provided by JPL

A scorching-hot gas planet beyond our solar system is steaming up with water vapor, according to new observations from NASA's Spitzer Space Telescope. The planet, called HD 189733b, swelters as it zips closely around its star every two days or so. Astronomers had predicted that planets of this class, termed "hot Jupiters," would contain water vapor in their atmospheres. Yet finding solid evidence for this has been slippery. These latest data are the most convincing yet that hot Jupiters are "wet." "We're thrilled to have identified clear signs of water on a planet that is trillions of miles away," says Giovanna Tinetti, a European Space Agency fellow at the Institute d'Astrophysique de Paris in France. Tinetti is lead author of a paper on HD 189733b appearing today in Nature. Although water is an essential ingredient to life as we know it, wet hot Jupiters are not likely to harbor any creatures. Previous measurements from Spitzer indicate that HD 189733b is a fiery 1,000 Kelvin (1,340 degrees Fahrenheit) on average. Ultimately, astronomers hope to use instruments like those on Spitzer to find water on rocky, habitable planets like Earth. "Finding water on this planet implies that other planets in the universe, possibly even rocky ones, could also have water," says co-author Sean Carey of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena. "I'm excited to tell my nephews and niece about the discovery." The new findings are part of a brand new field of science investigating the climate on exoplanets, or planets outside our solar system. Such faraway planets cannot be seen directly; however, in the past few years, astronomers have begun to glean information about their atmospheres by observing a subset of hot Jupiters that transit, or pass in front of, their stars as seen from Earth. Earlier this year, Spitzer became the first telescope to analyze, or break apart, the light from two transiting hot Jupiters, HD 189733b and HD 209458b. One of its instruments, called a spectrometer, observed the planets as they dipped behind their stars in what is called the secondary eclipse. This led to the first-ever "fingerprint," or spectrum, of an exoplanet's light. Yet, the results came up "dry," probably because the structure of these planets' atmospheres makes finding water with this method difficult. Later, a team of astronomers found hints of water in HD 209458b by analyzing visible-light data taken by NASA's Hubble Space Telescope. The Hubble data were captured as the planet crossed in front of the star, an event called the primary eclipse. Now, Tinetti and her team have captured the best evidence yet for wet, hot Jupiters by watching HD 189733b's primary eclipse in infrared light with Spitzer. In this method, changes in infrared light from the star are measured as the planet slips by, filtering starlight through its outer atmosphere. The astronomers observed the eclipse with Spitzer's infrared array camera at three different infrared wavelengths and noticed that for each wavelength a different amount of light was absorbed by the planet. The pattern by which this absorption varies with wavelength matches that created by water. "Water is the only molecule that can explain that behavior," says Tinetti. "Observing primary eclipses in infrared light is the best way to search for this molecule in exoplanets." The water on HD 189733b is too hot to condense into clouds; however, previous observations of the planet from Spitzer and other ground and space-based telescopes suggest that it might have dry clouds, along with high winds and a hot, sun-facing side that is warmer than its dark side. HD 189733b is located 63 light-years away in the constellation Vulpecula.

source: astronomy newsletter to me

srini

Quadruple Sunsets Possible on Other Worlds

Courtesy: space.com and yahoo news

Astronomers have spotted a dusty disk in a four-star solar system that could be home to a planet in the making.
Using the infrared eyes of NASA's Spitzer Space Telescope, astronomers spotted the swirling disk around a pair of stars in the quadruple-star system HD 98800, located 150 light-years away in the constellation TW Hydrae.
If a planet did form in the disk, its sky would be bathed in the light of four suns. One pair of suns would blaze brightly, while the other pair, gravitationally bound to the first pair, would appear as little more than faint pinpoints of light.
The finding will be detailed in an upcoming issue of The Astrophysical Journal.
So-called "circumstellar" disks like the one that rings HD 98800 can be the birthplace of planets. Most disks are smooth and continuous, but Spitzer detected a gap in the HD 98800 disk that could be evidence of one or more immature "protoplanets" carving out lanes in the dust.
"Planets are like cosmic vacuums,' said study team member Elise Furlan of the NASA Astrobiology Institute at the University of California, Los Angeles. "They clear up all the dirt that is in their path around the central stars."
Quadruple sunsets
The researchers spied two separate belts of material in the circumstellar disk. One belt sits at 1.5 to 2 astronomical units (AU) from the binary stars and likely consists of fine dust grains. The other is located about 5.9 AU away from and is probably made up of asteroids or comets. (One AU is equal to the distance between the Earth and the sun.) A swath of near-empty space separates the two belts, inside of which a budding planet might roam.
Alternatively, the researchers think the gap could be caused by a gravitational tug-of-war between the system's four stars. The other two stars are also doubled up, and the two binary pairs are separated by about 50 AU-slightly more than the distance between our sun and Pluto.
"Typically, when astronomers see gaps like this in a debris disk, they suspect that a planet has cleared a path," Furlan said. "However, given the presence of the diskless pair of stars sitting 50 AU away, the inward-migrating dust particles are likely subject to complex, time-varying forces, so at this point the existence of a planet is just speculation."
Not uncommon
The stars that make up each stellar doublet orbit around each other, and the two pairs circle one another as well.
Worlds with multiple sunsets are not uncommon. Astronomers used to think that strong gravitational forces from multiple stars might interfere with planet formation, but recent surveys have revealed that the dusty debris disks that function like nurseries for new planets are as common around double star systems as they are around single ones. A few triple-star systems are even known.
"Since many young stars form in multiple systems, we have to realize that the evolution of disks around them and the possible formation of planetary systems can be way more complicated and perturbed than in a simple case like our solar system," Furlan said.

Acknowledgements: Ker Than, staff writer, space.com and yahoo news

srini

A list of my blogs

For those who are interested further -

A list of my blogs including this one:

http://www.understandinguniverse.blogspot.com/
http://www.worldwide-wisdom.blogspot.com/
http://www.infiniteintelligence-bsrinivasan.blogspot.com/
http://www.laughter-land.blogspot.com/
http://www.life-longlife.blogspot.com/
http://www.astronauticsandaeronautics.blogspot.com/
http://www.shoppersstation.blogspot.com/
http://www.knowledgekeg.blogspot.com/
http://www.merrymusic.blogspot.com/
http://www.e-education-online.blogspot.com/

srini

Apollo 11 Launch, July 16, 1969

Courtesy: iMAGINE aRT

Folks! Happy rememberance of the 38th anniversary of the launch of Apollo 11, a successful moon voyager!

srini

Walk out - of Earth!

Ed White
First American Spacewalker

Courtesy iMAGINE aRT and NASA

srini

Jupiter Auroras "Northern Lights on Steroids"

March 30, 2007—No, Jupiter hasn't acquired a new toupee and goatee to impress Venus.

Those dashing purple puffs are x-ray images of the gas giant's high-voltage auroras—"northern lights on steroids," said planetary scientist Randy Gladstone of this image released yesterday by NASA.

The colorized picture is something of a collage. Several x-ray images taken by NASA's Chandra X-Ray Observatory have been combined and superimposed on the latest Hubble Space Telescope image of Jupiter.

"Jupiter has auroras bigger than our entire planet," said Gladstone, of the independent, nonprofit Southwest Research Institute in Texas, in a statement.

Gladstone hopes these latest observations will help him crack some Jovian mysteries. For starter, what causes these "hyper-auroras"?

The solar system's biggest planet and its magnetic field rotate extremely quickly—every ten hours—generating ten million volts around its poles. Toss in charged particles from the volcanic moon Io and you've got a crackling, nonstop sky show.

But how do the volcanic particles get from a relatively small moon to Jupiter's planetary poles? That, Gladstone says, remains one of the planet's unsolved puzzles.

courtesy: article by Ted Chamberlain in National geographic news

srini

Explode the myth on blackholes

Dear folks,
of late a lot theories are floated involving blackholes based on myths such as being made up of special particles (neutrinos etc.) or a pass through medium and so on. Systematic calculations reveal that a blackhole can be made of ANY material - solid, liquid or gas, any element or a mixture or compound. All it needs is a critical (minimum) size. Wanna have a blackhole of water ball or air or stone or gold or diamond? It is possible. To know more, visit this blog on 'understanding universe' at www.bsrinivasan.blogspot.com

bye

srini
astronomy

Discovery of an exoplanet - an earth-like planet

Astronomers have discovered the most earthlike planet outside our solar system to date, an exoplanet with a radius only 50% larger than the Earth and possibly having liquid water on its surface. Using the ESO 3.6m telescope, a team of Swiss, French, and Portuguese scientists discovered a super-Earth about 5 times the mass of the Earth that orbits a red dwarf, already known to harbor a Neptune-mass planet. The astronomers have also strong evidence for the presence of a third planet with a mass about 8 Earth masses. This exoplanet — as astronomers call planets around a star other than the Sun — is the smallest ever found up to now and it completes a full orbit in 13 days. It is 14 times closer to its star than the Earth is from the Sun. However, given that its host star, the red dwarf Gliese 581, is smaller and colder than the Sun — and thus less luminous — the planet nevertheless lies in the habitable zone, the region around a star where water could be liquid! "We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid," explains Stephane Udry, from the Geneva Observatory (Switzerland) and lead-author of the paper reporting the result. "Moreover, its radius should be only 1.5 times the Earth's radius, and models predict that the planet should be either rocky — like our Earth — or covered with oceans," he adds. "Liquid water is critical to life as we know it," avows Xavier Delfosse, a member of the team from Grenoble University (France). "Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X." The host star, Gliese 581, is among the 100 closest stars to us, located only 20.5 light-years away in the constellation Libra ("the Scales"). It has a mass of only one third the mass of the Sun. Such red dwarfs are at least 50 times intrinsically fainter than the Sun and are the most common stars in our Galaxy: among the 100 closest stars to the Sun, 80 belong to this class. "Red dwarfs are ideal targets for the search for such planets because they emit less light, and the habitable zone is thus much closer to them than it is around the Sun," emphasizes Xavier Bonfils, a co-worker from Lisbon University. Any planets that lie in this zone are more easily detected with the radial-velocity method, the most successful in detecting exoplanets. Two years ago, the same team of astronomers already found a planet around Gliese 581 (see ESO 30/05). With a mass of 15 Earth-masses, i.e. similar to that of Neptune, it orbits its host star in 5.4 days. At the time, the astronomers had already seen hints of another planet. They therefore obtained a new set of measurements and found the new super-Earth, but also clear indications for another one, an 8 Earth-mass planet completing an orbit in 84 days. The planetary system surrounding Gliese 581 contains thus no fewer than 3 planets of 15 Earth masses or less, and as such is a quite remarkable system. The discovery was made thanks to HARPS (High Accuracy Radial Velocity for Planetary Searcher), perhaps the most precise spectrograph in the world. Located on the ESO 3.6m telescope at La Silla, Chile, HARPS is able to measure velocities with a precision better than one metre per second (or 3.6 km/h)! HARPS is one of the most successful instruments for detecting exoplanets and holds already several recent records, including the discovery of another "Trio of Neptunes" (ESO 18/06, see also ESO 22/04). The detected velocity variations are between 2 and 3 metres per second, corresponding to about 9 km/h! That's the speed of a person walking briskly. Such tiny signals could not have been distinguished from 'simple noise' by most of today's available spectrographs. "HARPS is a unique planet hunting machine," says Michel Mayor, from Geneva Observatory, and HARPS Principal Investigator. "Given the incredible precision of HARPS, we have focused our effort on low- mass planets. And we can say without doubt that HARPS has been very successful: out of the 13 known planets with a mass below 20 Earth masses, 11 were discovered with HARPS!" HARPS is also very efficient in finding planetary systems, where tiny signals have to be uncovered. The two systems known to have three low mass planets — HD 69830 and Gl 581 — were discovered by HARPS. "And we are confident that, given the results obtained so far, Earth-mass planets around red dwarfs are within reach," affirms Mayor.

srini

The loneliest black holes

The loneliest black holes
Supermassive black holes are actively growing in even the emptiest regions of the universe.
Provided by Drexel University

This artist's impression of a supermassive black hole highlights the accretion disk of gas and stars swirling around the black hole, and the jets of material ejected along the poles. Supermassive black holes are found even where galaxies are sparse and interaction is minimal. These black holes accrete matter at a slower rate than black holes in denser galactic environments. A. Kamajian/NASA

This is a tiny extract from a newsletter to me from the Astronomy magazine. The readers may further enrich their knowledge by subscribing to it.

srini

June 6, 2007

In a study of more than 1,000 void galaxies, using data from the Sloan Digital Sky Survey (SDSS-II), astronomers from Drexel and Widener Universities announced that the growth of these monster black holes — with masses millions to hundreds of millions times that of our sun — are found where galaxies are sparse and interact very little with each other. The researchers also found that the accretion of matter onto these void black holes is slower than in denser galactic environments.These findings shed light on the black hole formation and evolution process by showing that the environment does affect how quickly galaxies proceed through their evolutionary cycle. The simple presence of growing supermassive black holes in the rural outposts of the universe challenges the current theoretical models of galaxy and structure formation and evolution, explained Anca Constantin of Drexel University, lead author of the paper delivered last week at the American Astronomical Society meeting in Honolulu. "Interestingly, we see actively accreting galactic black holes in all phases of evolution in these sparse regions," said Constantin. "This means that the black hole growth process is quite similar in what could be compared to the most reclusive countrysides and in the crowded urban regions of the universe." The void regions, nearly empty, three-dimensional fields hundreds of millions of light-years across, fill half of the universe. Only five percent of all galaxies live in these bubble-like regions. The other 95 percent of galaxies live together in communities, crowded into clusters, filaments, and walls: the cities and suburbs of the universe. Studying a 700-million light year wide 'slice' of the universe, the researchers found that spectra of the centers of void galaxies show hot gases ionized by light emitted from matter swirling around supermassive black holes. Constantin adds that, "the more isolated accreting black holes are however not as active as the ones in more populous environs, and the fuel seems less available for accretion in voids than in 'urban' galaxies." Astronomer Fiona Hoyle, a member of the discovery team from Widener University added: "This is strange given that these reclusive galaxies are forming stars at higher rates than their counterparts in denser regions; this means there is plenty of fuel, but it is not efficiently channeled toward the central engine."


Star formation requires the presence of large amounts of gas and so there must be more than enough gas in the void galaxies if their star forming rates are high, explained Hoyle. The smaller accretion rate observed in void galaxies means that this gas is just not getting down to the nuclear region where accretion happens. Interactions with other galaxies are thought to disturb the gravitational potential, which drives some gas into the nuclear region. "These interactions are not as frequent in voids, so the 'feeding' of the black hole is slower." These rugged individuals in voids do not need to compete with their neighbors for fuel, and their life cycle is rarely bothered, noted Constantin. In contrast, life is more hectic in crowded regions where galaxy interactions are frequent. As a consequence, galaxies are either stripped of their gas or more material is funneled toward the central engine. This means that there are many more chances the accretion onto black holes is enhanced or turned off in more 'urban environments.' "On the other hand, the void galaxy black holes might take longer to reach the mature, low accretion rate phase, which might explain why the most massive, lazy black holes are less frequent in voids," she noted. The data studied by Constantin may also show that active black holes appear to be more common in voids but only among small (less massive) galaxies, while less common among massive galaxies. This is also a clue that the life cycle of black hole growth in voids is delayed or slower compared to that in denser regions. Discovery team member Michael Vogeley of Drexel said that it's particularly puzzling that the few most massive and sluggishly accreting void systems live within the most secluded sub-regions, while their "urban" counterparts are found in the most populated neighborhoods. "Perhaps because massive objects are prone to accreting material around them, such a 'cleaning' process would contribute to emptying the already rarefied neighboring space in voids," Vogeley noted. "This would leave little or insufficient material for future formation of other nearby massive, bright galaxies." In contrast, within galaxy clusters where there is plenty of stuff around, accretion of surrounding material would make a small difference. These results have been possible only because of the sheer number of void regions and void galaxies found in the SDSS-II data, the most ambitious survey of the universe ever undertaken, the researchers said. The sample used in the analysis announced last week comprises more than 1,000 void galaxies. Previously, the black hole accretion in centers of void galaxies had been studied in only a handful of objects contained in only one void region, the Bootes Void.

Acknowledgements: Astronomy magazine's newsletter to me

srini

astronomy

giveawayoftheday

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This too is starscape as seen from Chile observatory. Any guesses about that red one?

srini

This is a picture of stars taken from an observatory in Chile.
What a catch?

srini

Discovery of planets - hoping to find life!

Data collected by NASA's orbiting Spitzer Space telescope on two Jupiter-like gas planets hundreds of trillions of kilometres away - one in the constellation of Pegasus and the other in the constellation of Vulpecula - point towards some vital evidences.

One of the planets had evidence of small sand-like particles, called silicates, in the atmosphere, sugesting it is wrapped in high, dusty clouds unlike any planet in our solar system. Spitzer observed for the first time enough light to figure out signatures of molecules in the atmospheres of planets outside our little one. It was deemed as a step in a long chain of events hopefuly leading to discovering life on some other planet.

These two planets - terrifically hot gas giants whizzing around their stars in alarmingly close orbits were considered to be unlikely to harbour life, presently. But scientists hoped to use similar techniques to scour smaller, rocky planets more like the Earth for indications of life, perhaps in the form of oxygen or possibly chlorophyll. The probability of water being there hidden by a thick layer of clouds, was not ruled out.

Finally, the 'present' must consider the time delay in getting the data - howmany lightyears of distance they are away etc.!

srini

Coming to nuclear density calculations!

Based upon the atomic radius of hydrogen (32 picometres) and the proportion of the volume of nucleus with respect to the total atomic volume (10**-13 approx), the nuclear density of hydrogen is 1/15 that of the core matter achieved after gravitational collapse, which means that the radius of the single proton is about 40% of the radius of the nucleus. But hold! we have to see what similar calculations on atoms of other elements have to say. It could be true that neutrons are smaller than thought to be.
Taking the case of Radon with atomic mass at 222a.m.u. and atomic radius at 140 picometres,
it can be seen that the nuclear density of Radon is about 2.5 times that of hydrogen. That means the protons and neutrons are more closely packed in the nuleus of Radon than in Hydrogen.
One has to do the exercise on sufficient number of samples to arrive at a reliable conclusion!

srini