There are two types of competitions conducted by the ASDRC. Two groups of competitors are tested by them. First is Dharmaraja College students. Students in grade 6 and above are tested and rated periodically to keep the standards of their knowledge. The idea beind that is promoting the knowledge as well as building a strong senior Astronomy quiz team to compete in national level quiz competitions representing the school. Second type of competitions are targeted for the countrywide, below college level students.

Having in mind their prorities, ASDRC conducts the ”Astro Olympiad” all-island inter school astronomy quiz competition and all-island inter school observation competition to enhance healthy competition between other schools in Sri Lanka.Quiz competition was first organized in year 2002 and is one of the oldest Astronomy quizzes in Sri Lanka. Usually this competition consists of a written preliminary round, 2 semi finals and a grand final. Both semifinals and final are oral. Preliminary round is divided into 5 sub sections as Cosmology and Astrophysics, General Astronomy, Rocketry and Space Science, History of astronomy and Archaeoastronomy and Observational astronomy. Best four teams selected from this round are taken into the semi finals and teams selected from them to the grand final. Winning team at the final is awarded the ”Astro Olympiad” challenge shield.

Observation competition was initiated in year 2006 and marked the beginning of 2nd sky observation competiion in Sri Lanka. It usually consists of 4 or 5 sky observation tasks depending on the visibility and availability of the objects. Usually competing teams get Lunar Sketching, Jupiter Obsevation, Saturn Obsevation, Mars Obsevation, Constellation Mapping and Deep Sky Obsevation as for their tasks. The best team at these tasks get the ASDRC obsevation shield.

Adapted from the Wikipedia article Astronomical Society of Dharmaraja College (ASDRC), under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Models based on general relativity play an important role in astrophysics, and the success of these models is further testament to the theory’s validity.

Gravitational lensing

Since light is deflected in a gravitational field, it is possible for the light of a distant object to reach an observer along two or more paths. For instance, light of a very distant object such as a quasar can pass along one side of a massive galaxy and be deflected slightly so as to reach an observer on Earth, while light

passing along the opposite side of that same galaxy is deflected as well, reaching the same observer from a slightly different direction. As a result, that particular observer will see one astronomical object in two different places in the night sky. This kind of focussing is well-known when it comes to optical lenses, and hence the corresponding gravitational effect is called gravitational lensing.

Observational astronomy uses lensing effects as an important tool to infer properties of the lensing object. Even in cases where that object is not directly visible, the shape of a lensed image provides information about the mass distribution responsible for the light deflection. In particular, gravitational lensing provides one way to measure the distribution of dark matter, which does not give off light and can be observed only by its gravitational effects. One particularly interesting application are large-scale observations, where the lensing masses are spread out over a significant fraction of the observable universe, and can be used to obtain information about the large-scale properties and evolution of our cosmos.

Gravitational waves

Gravitational waves, a direct consequence of Einstein’s theory, are distortions of geometry which propagate at the speed of light, and can be thought of as ripples in space-time. They should not be confused with the gravity waves of fluid dynamics, which are a different concept.

Indirectly, the effect of gravitational waves has been detected in observations of specific binary stars. Such pairs of stars orbit each other and, as they do so, gradually lose energy by emitting gravitational waves. For ordinary stars like our sun, this energy loss would be too small to be detectable, but this energy loss was observed in 1974 in a binary pulsar called PSR1913+16. In such a system, one of the orbiting stars is a pulsar. This has two consequences: a pulsar is an extremely dense object known as a neutron star, for which gravitational wave emission is much stronger than for ordinary stars. Also, a pulsar emits a narrow beam of electromagnetic radiation from its magnetic poles. As the pulsar rotates, its beam sweeps over the Earth, where it is seen as a regular series of radio pulses, just as a ship at sea observes regular flashes of light from the rotating light in a lighthouse. This regular pattern of radio pulses functions as a highly accurate “clock”. It can be used to time the double star’s orbital period, and it reacts sensitively to distortions of space-time in its immediate neighborhood.

The discoverers of PSR1913+16, Russell Hulse and Joseph Taylor, were awarded the Nobel Prize in Physics in 1993. Since then, several other binary pulsars have been found. The most useful are those in which both stars are pulsars, since they provide the most accurate tests of general relativity.

Currently, one major goal of research in relativity is the direct detection of gravitational waves. To this end, a number of land-based gravitational wave detectors are in operation, and a mission to launch a space-based detector, LISA, is currently under development, with a precursor mission (LISA Pathfinder) due for launch in June 2011. If gravitational waves are detected, they could be used to obtain information about compact objects such as neutron stars and black holes, and also to probe the state of the early universe fractions of a second after the Big Bang.

Black holes

When mass is concentrated into a sufficiently compact region of space, general relativity predicts the formation of a black hole& – a region of space with a gravitational attraction so strong that not even light can escape. Certain types of black holes are thought to be the final state in the evolution of massive stars. On the other hand, supermassive black holes with the mass of millions or billions of Suns are assumed to reside in the cores of most galaxies, and they play a key role in current models of how galaxies have formed over the past billions of years.

Matter falling onto a compact object is one of the most efficient mechanisms for releasing energy in the form of radiation, and matter falling onto black holes is thought to be responsible for some of the brightest astronomical phenomena imaginable. Notable examples of great interest to astronomers are quasars and other types of active galactic nuclei. Under the right conditions, falling matter accumulating around a black hole can lead to the formation of jets, in which focused beams of matter are flung away into space at speeds near that of light.

There are several properties that make black holes most promising sources of gravitational waves. One reason is that black holes are the most compact objects that can orbit each other as part of a binary system; as a result, the gravitational waves emitted by such a system are especially strong. Another reason follows from what are called black hole uniqueness theorems: over time, black holes retain only a minimal set of distinguishing features (since different hair styles are a crucial part of what gives different people their different appearances, these theorems have become known as “no hair” theorems). For instance, in the long term, the collapse of a hypothetical matter cube will not result in a cube-shaped black hole. Instead, the resulting black hole will be indistinguishable from a black hole formed by the collapse of a spherical mass, but with one important difference: in its transition to a spherical shape, the black hole formed by the collapse of a cube will emit gravitational waves.

Cosmology

One of the most important aspects of general relativity is that it can be applied to the universe as a whole. A key point is that, on large scales, our universe appears to be constructed along very simple lines: All current observations suggest that, on average, the structure of the cosmos should be approximately the same, regardless of an observer’s location or direction of observation: the universe is approximately homogeneous and isotropic. Such comparatively simple universes can be described by simple solutions of Einstein’s equations. The current cosmological models of the universe are obtained by combining these simple solutions to general relativity with theories describing the properties of the universe’s matter content, namely thermodynamics, nuclear- and particle physics. According to these models, our present universe emerged from an extremely dense high-temperature state (the Big Bang)

roughly 14 billion years ago, and has been expanding ever since.

Einstein’s equations can be generalized by adding a term called the cosmological constant. When this term is present, empty space itself acts as a source of attractive or, unusually, repulsive gravity. Einstein originally introduced this term in his pioneering 1917 paper on cosmology, with a very specific motivation: contemporary cosmological thought held the universe to be static, and the additional term was required for constructing static model universes within the framework of general relativity. When it became apparent that the universe is not static, but expanding, Einstein was quick to discard this additional term; prematurely, as we know today: From about 1998 on, a steadily accumulating body of astronomical evidence has shown that the expansion of the universe is accelerating in a way that suggests the presence of a cosmological constant or, equivalently, of a dark energy with specific properties that pervades all of space.

Adapted from the Wikipedia article Introduction to general relativity, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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The basic principles of explaining the origin of the elements and the energy generation in stars were laid down in the theory of nucleosynthesis which came together in the late 1950s from the seminal works of Burbidge, Burbidge, Fowler, and Hoyle in a famous paper and independently by Cameron. Fowler is largely credited with initiating the collaboration between astronomers, astrophysicists, and experimental nuclear physicists which is what we now know as nuclear astrophysics.

The basic tenets of nuclear astrophysics are that only isotopes of hydrogen and helium (and traces of lithium, beryllium, and boron) can be formed in a homogeneous big bang model (see big bang nucleosynthesis), and all other elements are formed in stars. The conversion of nuclear mass to kinetic energy (by merit of Einstein’s famous mass-energy relation in relativity) is the source of energy which allows stars to shine for up to billions of years. Many notable physicists of the 19th century, such as Mayer, Waterson, von Helmholtz, and Lord Kelvin, postulated that the Sun radiates thermal energy based on converting gravitational potential energy into heat. The lifetime of the Sun under such a model can be calculated relatively easily using the virial theorem, yielding around 19 million years, an age that was not consistent with the interpretation of geological records or the then recently proposed theory of biological evolution. A back of the envelope calculation indicates that if the Sun consisted entirely of a fossil fuel like coal, a source of energy familiar to many people, considering the rate of thermal energy emission, then the Sun would have a lifetime of merely four or five thousand years, which is not even consistent with records of human civilization. The now discredited hypothesis that gravitational contraction is the Sun’s primary source of energy was, however, reasonable before the advent of modern physics; radioactivity itself was not discovered by Becquerel until 1895. Besides the prerequisite knowledge of the atomic nucleus, a proper understanding of stellar energy is not possible without the theories of relativity and quantum mechanics.

After Aston demonstrated that the mass of helium is less than four times the mass of the proton, Eddington proposed that in the core of the Sun, through an unknown process, hydrogen was transmuted into helium, liberating energy. 20 years later, Bethe and von Weizsäcker independently derived the CN cycle, the first known nuclear reaction cycle which can accomplish this transmutation; however, it is now understood that the Sun’s primary energy source is the pp-chains, which can occur at much lower energies and are much slower than catalytic hydrogen fusion. The time-lapse between Eddington’s proposal and the derivation of the CN cycle can mainly be attributed to an incomplete understanding of nuclear structure, and a proper understanding of nucleosynthetic processes was not possible until Chadwick discovered the neutron in 1932 and a contemporary theory of beta decay developed. Nuclear physics gives a self-consistent picture of the energy source for the Sun and its subsequent lifetime, as the age of the solar system derived from meteoritic abundances of lead and uranium isotopes is about 4.5 billion years. A star the mass of the Sun has enough nuclear fuel to allow for core hydrogen burning on the main sequence of the HR-diagram via the pp-chains for about 9 billion years, a lifetime primarily set by the extremely slow production of deuterium,

which is governed by the nuclear weak force.

Adapted from the Wikipedia article Nuclear astrophysics, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Astrophysics and Space Science is a peer reviewed academic journal in the field of astrophysics and space science. It publishes original contributions, invited reviews and conference proceedings over the entire range of astronomy, astrophysics and space science. This includes observational and theoretical papers as well as those concerned with the techniques of instrumentation.

Adapted from the Wikipedia article Astrophysics and Space Science, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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He attended Torquay Boys’ Grammar School in Devon, whilst living in Churston Ferrers. Whilst at school, in 1999, he won a $500 Earth and Space Sciences award and the Priscilla and Bart Bok Honorable Mention Award at the Intel International Science and Engineering Fair for an article on ”Dust Around Young Stellar Objects”. This came from a six week project at the University of Hertfordshire funded by a Nuffield bursary. Lintott read for a degree in Natural Sciences from the University of Cambridge where he was a student of Magdalene College. He received a PhD in astrophysics from University College London, where his thesis was on the subject of star formation. He is a fellow of the Royal Astronomical Society and is presently a researcher in the Department of Physics at the University of Oxford and a junior research fellow at Somerville College. His research there focuses on galaxies, galaxy evolution, and on the application of astrochemical models of star formation to galaxies beyond the Milky Way; particularly the use of sulphur compounds as a signature of stars that are in the process of forming.

Adapted from the Wikipedia article Chris Lintott, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Adapted from the Wikipedia article Fermi Gamma-ray Space Telescope, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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non-standard cosmology is any physical cosmological model of the universe that has been, or still is, proposed as an alternative to the big bang model of (standard) physical cosmology. In the history of cosmology, various scientists and researchers have disputed parts or all of the big bang due to a rejection or addition of fundamental assumptions needed to develop a theoretical model of the universe. From the 1940s to the 1960s, the astrophysical community was equally divided between supporters of the big bang theory and supporters of a rival steady state universe. It was not until advances in observational cosmology that the big bang would eventually become the dominant theory, and today there are few active researchers who dispute it. The term “non-standard” is applied to any cosmological theory that does not conform to the scientific consensus. Today it is also used to describe theories that accept a “big bang” occurred but differ as to the detailed physics of the origin and evolution of the universe.

Adapted from the Wikipedia article Non-standard cosmology, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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The theory of stellar nucleosynthesis reproduces the chemical abundances observed in the solar system and galaxy, which from hydrogen to uranium, show an extremely varied distribution spanning twelve orders of magnitude (one trillion). While impressive, these data were used to formulate the theory, and a scientific theory must be predictive in order to have any merit. The theory of stellar nucleosynthesis has been well-tested by observation and experiment since the theory was first formulated.

The theory predicted the observation of technetium (the lightest chemical element with no stable isotopes) in stars, observation of galactic gamma-emitters such as 26Al and 44Ti, observation of solar neutrinos, and observation of neutrinos from supernova 1987a. These observations have far-reaching implications. 26Al has a lifetime a bit less than one million years, which is very short on a galactic timescale, proving that nucleosynthesis is an on-going process even in our own time. Work which lead to the discovery of neutrino oscillation, implying a non-zero mass for the neutrino and thus not predicted by the Standard Model of particle physics, was motivated by a solar neutrino flux about three times lower than expected, which was a long-standing concern in the nuclear astrophysics community such that it was colloquially known simply as the Solar neutrino problem. The observable neutrino flux from nuclear reactors is much larger than that of the Sun, and thus Davis and others were primarily motivated to look for solar neutrinos for astronomical reasons.

Adapted from the Wikipedia article Nuclear astrophysics, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Canadian Institute for Theoretical Astrophysics (CITA) is a national research institute funded by the Natural Sciences and Engineering Research Council, located at the University of Toronto in Toronto, Ontario, Canada. CITA’s mission is “to foster interaction within the Canadian theoretical Astrophysics community and to serve as an international center of excellence for theoretical studies in astrophysics.” CITA was incorporated in 1984.

CITA has close administrative and academic relations with the Canadian Institute for Advanced Research (CIFAR); several CITA faculty also served as members of CIFAR.

Adapted from the Wikipedia article Canadian Institute for Theoretical Astrophysics, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years (for the most massive) to trillions of years (for the least massive, which is considerably more than the age of the universe).

Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at the various points in their life, and by simulating stellar structure with computer models.

Adapted from the Wikipedia article Stellar evolution, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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