What happens to a star heavier than five solar masses? ... Stars about ten solar masses probably behave like our five solar mass star until they reach the end of core-helium burning. ... The Crab nebula was formed after a massive explosion ripped a star apart in 1054. ... Today, the glowing outer layers of the star are still rushing away from a tiny star in the centre. ... An incredible explosion rips through the outer layers of the star, releasing colossal amounts of energy in a supernova explosion. ...

... The Sun is powered by nuclear fusion: hydrogen `burns' to form helium, releasing energy . ... At an age of ~10 billion years (slightly over twice its present age), the Sun will exhaust the fuel available in its core. ... Pressure overwhelms gravity, and over a period of a few hundred thousand years, the Sun evolves into a `red giant' . ... Red giants have lifetimes of less than 100 million years. The temperature in the red giant core increases to 100 million degrees . ... The Ring Nebula . ...

... Globular cluster NGC 2808, elliptical galaxy NGC 2986, and the Sextans Dwarf . ... What would cause Earthт??s orbit to become more circular instead of its present elliptical orbit, and has this ever happened before? ... Gravitational interactions among the planets cause the ellipticities of the orbits to oscillate periodically by a few percent over millions of years. Get instant access to subscriber content on Astronomy.com! ... If you are already registered on Astronomy.com, please log in below. ...

... If the mass of the collapsing star is more than three solar masses, however, no force can prevent it from collapsing completely to become a black hole. What is a black hole? Mini black holes . ... For Further Reading About Black Holes A black hole is a region of space in which the pull of gravity is so strong that nothing can escape. ... A black hole with a mass less than three solar masses would not form on its own; its gravity is too weak to cause it to completely collapse in on itself. ...

... More on 51 Peg: . The discovery of a Jupiter--mass planet in orbit around the solar--type star 51Peg has been reported by Michel Mayor and Didier Queloz (Geneva Observatory) on October 6th at the 9th Cambridge workshop on "cool stars, stellar systems, and the sun" held at Florence (Italy). ... Recall that the measurements of radial velocity only yield v sin i which in turn gives us M sin i. For most values of i, sin i will be greater than 0.5 and this gives a mass estimate of 0.5 Jupiter masses. ...

... Red stars are cool, with temperatures of around 3,000 degrees Kelvin (K), while blue stars are hotter and can have temperatures over 30,000 degrees K. Our own lovely yellow Sun's temperature is a comforting 6,000 degrees K. Star Trails in Northern Skies . ... Aurora Astern . ... Well, probably not ... but it is the most active volcanic moon. Active volcanoes on Jupiter's moon Io were a surprise discovery of the Voyager missions of the late 1970s. Comet-like Clouds in the Cartwheel Galaxy . ...

... Electric field is a potential heat source for ionospheric particles (Rees, 1989). It is due to the fact that, under the action of an electric field, charged particles drift relative to one another and relative to neutral particles. ... This is called frictional heating. ... However, the effect of frictional/Joule heating of neutrals in the auroral electrojet region can lead to upward neutral wind in a region of high electron densities and strong electric fields (Winser et. al., ...

... Meta Index / Home Page This section documents warnings and errors generated by this task (if any). ... The Keyword TIMEDEL should be present in the input file . ... corrective action: CONTENT keyword should be present in the input file header . ... Count rate errors negative . ... corrective action: Count rate errors must be positive . ... corrective action: TSTART keyword should be present in header of GTI file . ... corrective action: TSTOP keyword should be present in header of GTI file . ...

... STScI-PRC98-21 A BRIGHT RING OF STAR BIRTH AROUND A GALAXY'S CORE An image from NASA's Hubble Space Telescope reveals clusters of infant stars that formed in a ring around the core of the barred-spiral galaxy NGC 4314. ... This close-up view by Hubble also shows other interesting details in the galaxy's core: dust lanes, a smaller bar of stars, dust and gas embedded in the stellar ring, and an extra pair of spiral arms packed with young stars. ... However, they are older than those in the ring. ...

not-minutes' for second E-ALFA LOC Meeting Tuesday, April 13th Present: Chris S., A. Desh, Carmen S., Jose A. Erik M. Telecon: Bob B., Karen O. Items outstanding or pending items from last meetings action list: ACTION - Karen O: Update w/site to include a strong recommendation for all visitors to use calling cards. ... ACTION - Chris S.: Check the price of telecon with Jill. ... Deferred to Lister Staveley-Smith (ATNF) ACTION: Karen O. to arrange for Info Handouts Pending actual content of handouts. ...

Recent Changes - Search : . ... PmWiki . ... Go to new wiki . ... Custom WikiStyles | ... action= browse . display the specified page (default action if no ?action= is present) . ... edit the specified page . ... show a change history of the specified page . ... displays dialog for setting/changing password of the specified page . ... display the specified page using the skin specified by $ActionSkin['print'] . ... performs search with searchterm and displays results on current page . ...

Deep Time: Earth's history and future By Colin Johnston, Armagh Planetarium Earth 4.54 billion years ago Forms in Sun's protoplanetary disc S un Elsewhere in Solar System Other planets form. ... Hot and airless Sun a subgiant, diameter 1.5 its current value, 2 6.4 billion years from no w ? ... Earth cools 20 million years later? ... Core temperature about 55 million°C, helium flash, followed by the Sun shrinking Sun is 10 times its current diameter, luminosity 20-50% current value. ...

... A rough estimation is that in the United States there is one planetarium per 100,000 population, ranging in size from the Hayden Planetarium's 20-meter dome seating 430 people, to three-meter inflatable portable domes where children sit on the floor. ... Together dblo associates make a huge impact in the architecture, interior design and development arena in London. ... With the holidays around the corner what better way to spoil your family than with your very own private home cinema. ...

... Unsafe act - a behavioral departure from an accepted, normal, or correct procedure or practice which, in the past, has produced injury or property damage or which has potential for doing so in the future; an unnecessary exposure to a hazard; conduct reducing the degree or safety normally present in an activity. ... Any hazardous unsafe condition, or act that presents a situation of imminent danger to life and/or property requires urgent action. ...

Next: Radiopulsars as Sources of Up: Cosmic Rays and Evolution Previous: Cosmic Rays and Evolution . Presently, there is little doubt that galactic CR can be generated at rapidly expanding shock fronts produced by supernova explosions. ... Statistical properties of radiopulsars in our Galaxy indicate a formation rate of NS of about 1 per 10-20 years in the present cosmological epoch, while direct astronomical observations have so far not detected supernova explosions at this high rate. ...

... ESO, the European Southern Observatory . ... Travel and Contacts . ... Travel to E-ELT Armazones . ... Survey Telescopes . ... Galaxies . ... This galactic pile-up, formed by the collision of two galaxies, provides an excellent opportunity for astronomers to study how mergers affect the evolution of the Universe. ... Atoms-for-Peace: a galactic collision in action* . ... Zooming in on Atoms-for-Peace: a galactic collision in action . ... Pan over Atoms-for-Peace: a galactic collision in action . ...

... Future seminars . ... Relativistic magneto-active laser plasmas " . ... Generation of super-strong magnetic fields. ... This method is based on the observation of resonance interaction between the Landau levels in magnetic field and energy levels of plasma ions. ... The important peculiarity of the energy distribution of fast ions is their slow decreasing up to the energy of 1.4 MeV at the laser intensity of 2 10 18 W/cm 2 ; the effective temperature of fast ions is of the order of 350 keV. ...

Next: Imaging by an Optimizing Method . ... A big advantage of this numerical integrator is its stability: the error in the semi-major axis and the eccentricity depends only on the step size and does not grow with an increasing number of time steps. ... As the integration time increases, the numerical results become more contaminated by various errors. ... A new symplectic integrator produces no secular truncation errors in the actions of a Hamiltonian system. ...

Today's Picture: June 23, 1995 . Gamma Ray All Sky Map . Picture Credit: NASA, Compton Gamma Ray Observatory . Explanation: What if you could "see" gamma rays? This computer processed image represents a map of the entire sky at photon energies above 100 million electron Volts. ... In the early 1990s NASA's Compton Gamma Ray Observatory, in orbit around the Earth, scanned the entire sky to produce this picture. ... We keep an archive of previous Astronomy Pictures of the Day. ...

OptInt PmWiki : Pm Wiki / Available Actions . Default actions . ... Cookbook actions . Page actions are applied to wiki pages, as a query string appended to the URL . ... displays dialog for setting/changing password of the specified page or group of pages, see passwords , see also $EnablePostAttrClearSession if you do not want to have the session cleared after validating change General use of passwords . ... display the specified page (default action if no ?action= is present) . ...