JamesSavik

The muses, those whores of inspiration, For their gifts, they demand persipration. They come not gift-wrapped or for free, but with work they will come to thee.

New Life in Dead Star: Supernova 'Changing Right Before Our Eyes' Ker Than for Space.com July 24, 2006 Source Link This image of SN 1987A combines data from NASA's orbiting Chandra X-ray Observatory and the 8-meter Gemini South infrared telescope in Chile. The X-ray light detected by Chandra is colored blue. The infrared light detected by Gemini South is shown as green and red. The ring is produced by hot gas (largely the X-ray light) and cold dust (largely the infrared light) from the exploded star interacting with the interstellar region. Credit: Gemini/NASA _________________________________________________________________ Newly detected dust found around the burst remains of a dead star could help reveal how planets and stars formed and how life began. About 160,000 years ago, a star 20 times more massive than our sun erupted in a fiery explosion called a supernova. The star was located in the Large Magellanic Cloud, a nearby dwarf galaxy. In 1987, the first light from that catastrophic event reached Earth and for several months, the supernova, dubbed SN 1987A, blazed as brightly as 100 million suns before fading again. Now, nearly two decades later, astronomers have detected dust particles around the supernova that they think formed before the star exploded. The new finding is the first evidence that star dust can survive a supernova explosion. It is also providing a rare glimpse into a process called "sputtering," in which dust is eroded by interactions with superheated gas. "Supernova 1987A is changing right before our eyes," said Eli Dwek, a cosmic dust expert at NASA Goddard Space Flight Center in Maryland who was involved in the finding. "What we are seeing is a milestone in the evolution of a supernova." Cosmic building blocks Finer than grains of beach sand, stellar dust is a constant source of frustration for astronomers because it can obscure observations from distant stars. Yet the troublesome dust is also a prime ingredient in the construction of planets and of all living things. The dust is made in the fiery furnaces of stars as they burn and is scattered across space either by stellar winds or by supernova explosions. Despite its importance, scientists still know very little about star dust. How much dust does a star produce throughout its lifetime? How much survives a star's death? And how do rings of dust coalesce to form stars and planets? 1987A's newly detected stardust, found using an infrared telescope at the Gemini South Observatory in Chile, could help astronomers answer these questions. The dust particles are intermixed with superheated, X-ray emitting gas and found within an equatorial ring around SN 1987A. About a light-year across, the ring of gas and dust is expanding very slowly. This suggests that the ring was created about 600,000 years before the star exploded, the researchers say. It is therefore unlikely that the ring was created by a supernova blast during the star's death, but rather by stellar winds when the star was still alive. Made visible The ring of dust and gas remained invisible for nearly twenty years until shockwaves from the supernova blast caught up with it. As the shockwaves expanded, they passed through the ring, heating up its gas and normally cool dust until they glowed in the infrared. "This much was expected," said study team member Patrice Bouchet of the Observatoire de Paris. "The collision between the ejecta of supernova 1987A and the equatorial ring was predicted to occur sometime in the interval of 1995 to 2007, and it is now underway." What was surprising, however, was the composition of the dust, which followup observations with NASA's Spitzer Space Telescope revealed to be almost pure silicate. Also, far less dust than expected was detected. A star as massive as the one that created SN 1987A was thought to produce much more dust. The dearth of dust could mean that shockwaves from the supernova blast destroyed more dust than originally thought. This could have broad implications for determining dust origins throughout the universe if confirmed, the researchers say. A spate of new infrared, optical and X-ray observations of SN 1987A are now planned to follow up on the new findings. ___________________________________________________________________ Core of Supernova Goes Missing Michael Schirber for Space.com June 6, 2005 Source Link The remnant of supernova 1987A shows no sign of the neutron star scientists believe is lurking at its heart. The Hubble Space Telescope took this image in December 2004. Credit: P. Challis & R. Kirshner, Harvard-Smithsonian Center for Astrophysics ____________________________________________________________________ A search for the remains of a nearby stellar explosion has come up empty. Astronomers observed the blast site of the supernova, SN 1987A, with the Hubble Space Telescope, but could not find any sign of the dense stellar core. "We think a neutron star was formed. The question is: Why don't we see it?" astronomer Genevieve Graves of UC Santa Cruz said today. A neutron star is an extremely dense ball of subatomic particles, which theory says can form as the core of a massive star collapses after exploding. This is what is believed to have happened in 1987, when a star with 20 times the mass of our Sun blew up, 165,000 light-years away in the Large Magellanic Cloud. "Therein lies the mystery -- where is that missing neutron star?" said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics (CfA). Neutron stars are often detected as pulsars when they emit intense beams of radio waves, like a lighthouse. It may be too soon to see radio flashes from the remnant of SN 1987A, since theory predicts that pulsars take between 100 to 100,000 years to develop after a supernova. A young neutron star could, however, be seen if it is swallowing up nearby gas and debris from the explosion. This accreted material would heat up and emit light. But when the team of astronomers scoured the area of SN 1987A, they found no signature of this accretion. "A neutron star could just be sitting there inside SN 1987A, not accreting matter and not emitting enough light for us to see," said Peter Challis from the CfA. Future observations may uncover this quiet remnant by studying the infrared emission from dust clouds in the vicinity, which may be reprocessing the weak ultraviolet and visible light coming from the neutron star. A supernova from a more massive star can form a black hole, instead of a neutron star. The progenitor of SN 1987A is right near the dividing line, so it may have created a black hole. Still, a black hole would be indirectly detectable by the same accretion mechanism that was not seen in these latest results. _______________________________________________________________ Hubble Reveals Dramatic New Phase of a Supernova Explosion Robert Roy Britt for Space.com 19 February 2004 Source Link A sequence of Hubble images of supernova 1987A taken from 1994 through late 2003 shows the central star has faded while bright spots in the outer ring are enhanced. ________________________________________________________________ The most dramatic stellar explosion witnessed in centuries just got more interesting. New images from the Hubble Space Telescope show a dying star's "ring of fire" entering a new phase of brightness. The remarkable event is the only one of its kind ever recorded by telescopes. Astronomers first saw the star explode -- an event called a supernova -- in 1987. It shone as bright as 100 million suns for several months. Robert Kirshner of Harvard University and the Harvard-Smithsonian Center for Astrophysics led the latest observations. He explained what's going on around the star named 1987A. When the star first exploded, ultraviolet light raced outward and lit up a previously unknown ring of gaseous debris that the star had presumably spat out about 20,000 years prior. "Then there's a blast wave going out from the supernova to the ring," Kirshner said in a telephone interview. "We all knew it was going to hit in a decade or so." Shock wave hits In 1996, that shock wave began to plow into the debris ring, which is about a light-year in diameter. It heated the ring material -- gas and dust -- in spots, created an increasing number of bright areas that Hubble has been documenting over the years. In the latest image, the spots nearly cover the ring like pearls on a necklace. The star, meanwhile, is a million times dimmer than when it first exploded. The fact that the ring did not light up all at once suggests it is not perfectly round but instead is unstable, with parts of the inner ring closer to the central star than other parts, Kirshner said. He described it as a corrugated structure, or a wall with stalactites sticking inward. Inside the ring, an amorphous purplish blob surrounds the central, dying star. That blob glows because it's made of radioactive elements forged in the supernova explosion. It is probably radioactive titanium, Kirshner explained, "shredded bits of the star going out at about 3,000 kilometers per second," or 6.7 million mph. "Looking at the expansion of that [blob] we get a clue to what was happening in first couple of minutes of the explosion of the star," he said. Scientists have seen no other supernova evolve over time with anything approaching this sort of detail. Show continues The ring around 1987A should continue to brighten for a couple of decades, Kirshner said. The bright spots will merge as the debris is engulfed by the shock wave until it creates a "ring of fire," he said. Watching the evolution should help theorists understand how and why stars explode. "There's going to be plenty to see," Kirshner said. But its uncertain whether 1987A will be monitored continuously. Like many astronomers, Kirshner said he's disappointed that under NASA's current plans, Hubble won't be around to record 1987A's progress in the latter years of this decade. The activity can be studied by X-ray and radio observatories, but valuable visible-light data would go uncollected. "The value of the data keeps getting bigger as we get a longer series," Kirshner said. He added that it could be a long time before a similar event is available to astronomers and Hubble "is one of our chief instruments for doing this." The last supernova to shine so brightly in Earth's skies was spotted by Johannes Kepler 400 years ago. 1987A was generated by a star 20 times more massive than the Sun. It resides in a nearby galaxy called the Large Magellanic Cloud. Because of the time it takes light from the event to reach Hubble, the explosion actually occurred 160,000 years ago, in the time frame of its origin. _______________________________________________________________ This is a wide field image from the Hubble taken of the remnant of SN 1987A. The background is the Large Magellanic Cloud-- a nearby galaxy observable from the southern hemisphere. This image of SN 1987A was voted #6 of the Hubble's top 10 most valuable science images.

Is this what the Brits mean when they say "cheeky bugger"?

We had a friend that decided to go bald like that. People kept asking him how long he had had cancer so he grew it back.

My apologies again to the Mac legions Ryan. I should have thought of a "Mac" option when I set up the poll. I thought I was being progressive when I included Linux.

Here lately it has either been storming (not just raining) or 100+ degrees.

Maybe Nifty is tightening up. They have gotten a lot of criticism for some of their stories with more... controversial themes. While I am dead set against censorship, writers have to be aware that there is a good old fashioned witch-hunt in progress complete with angry mobs, pitchforks and torches. Bush's hair-brained minions don't really care whose head they put on a pig-pole because it's not really about justice. It's about being able to grandstand for the cameras and say see, we made you safer.

Writing Great Short Stories Lucke, Margaret McGraw-Hill, 1999. ISBN# 0-07-039077-0 Google Book Entry Short stories are both the easiest and most difficult form to write. Unlike a novel, a short story can't wander around a point for 25,000 words. Every word must be chosen with care taking into consideration its purpose. This book turns out to be an excellent starting place for a novice author. It is short, hits all of the requisite points and isn't pretentious. It also enjoys the great virtue of being inexpensive. Table of Contents I. Writing a Short Story II. Characters- How to Create People Who Live & Breath on the Page III. Conflict- How to Devise a Story That Readers Won't Want to put Down IV. Plot & Structure- How to Shape Your Story and Keep it Moving V. Setting & Atmosphere- How to Bring Readers into a Vivid World VI. Narrative Voice- How to Develop Your Individual Voice as a Writer The book also contains exercises and how to format your work for submission to publishers. Writing Great Short Stories is a good book for beginners but experienced authors may find it too basic to be very useful.

There are two types of supernova: Type I and Type II. Then there are numerous sub-species which are spectroscopic variations on those two themes. Type I supernova are always white dwarf stars that have grown beyond the Chandrasekhar limit- the maximum mass possible for a white dwarf. When a white dwarf accumulates mass in excess of between 1.2 to 1.4 solar masses[there is some debate on this exact number]. Matter in the state of a white dwarf at that density and pressure becomes unstable and explodes. Type II supernova are very different. This event marks the end point of a massive stars evolution. Giant stars operate like huge reactors. Because of their size and mass, the gravitational pressure of the star on it's core is huge. Under these conditions, the fusion reactions proceed at a furious rate. Such stars are very short-lived. It only takes 10-40 Myrs for one of these giants to burn through their core fuel. First hydrogen is fused into helium, and in successive phases the stars core fuel will be built up- oxygen, nitrogen then carbon. When the core has become Iron, that's when trouble begins. The energy of an Iron fusion reaction is insufficient to keep the star in hydrostatic equilibrium and the star's core collapses. The explosion part of a type II is the rebound from its core. Type II SN are quite rare and are usually seen at extra-galactic distances. In 1987, a SN occurred in the LMC, some 150,000 lyrs away, which is a mere drop in the bucket by cosmic standards. It gave us our first opportunity to study one of these events relatively "close up" with modern instruments. Supernovas play a very important role in stellar evolution. They are the furnace in which all elements heavier than iron are formed. They enrich the interstellar medium with important elements like Nitrogen, Oxygen, Carbon, Silicon, etc. Their massive shock waves are known to trigger star formation by compressing nebular gas which leads gas clouds to collapse under their own gravity. I've studied SN 1987A since it occurred and continue to follow its progress. It created a millisecond pulsar and its ejected shell continues to expand. I have some 80 books and hundreds of papers on the topic. The LMC and SMC are important objects of study: as small galaxies interacting with one another and the Milky Way, as a stellar nursery and laboratory to study the life cycle of stars. They are only observable by ground based observers in the southern hemisphere. My idea of heaven would to be to retire to Australia and study the Magellanic Clouds. This is the Tarantula Nebula in the Large Magellanic Cloud. It is a region of prolific star formation and is quite beautiful. Notice the hot, young blue and white stars in contrast it with the older red giant.

Stellar explosion revealed in unique detail David Shiga for NewScientist.com news service July 19, 2006 Source Link The material collected from the red giant leads to a nuclear explosion on the surface of its companion, a white dwarf star (Artist's impression: David A Hardy/PPARC) ____________________________________________________________________ An unprecedented glimpse of the blast wave from an erupting star has been seen by astronomers. The new view suggests the binary system observed could be responsible for some of the universe's most powerful explosions, called Type Ia supernovae. These are very important to astronomers as they are used as "standard candles" to measure distances, but their source has been a major mystery in astronomy. The explosion occurred in a binary star system called RS Ophiuchi. It consists of a red giant star orbited by the dense core of a burned-out star, called a white dwarf. The outbursts occur because the white dwarf slowly collects gas shed by the red giant. When enough gas piles up on the white dwarf, the mounting pressure triggers a tremendous nuclear explosion. RS Ophiuchi explodes this way every few decades, but not with a regular schedule. Before the latest outburst, it had not exploded since 1985. Astronomers were therefore excited to discover a new explosion in progress on 12 February 2006. They were able to track the blast wave's progress sooner after its onset and in more detail than ever before. "We really saw much, much more this time," says Jennifer Sokoloski of the Harvard-Smithsonian Center for Astrophysics, in Cambridge, US. Sokoloski led a team that observed the event with the Rossi X-ray Timing Explorer (RXTE), starting the day after the initial detection of the outburst. Flickering candles The researchers found evidence that the system was on its way to producing a Type Ia supernova. Although these are used as standard candles, there are in fact slight differences in their brightness. This adds uncertainty to distance measurements. Part of the problem is that astronomers do not know for sure what causes the supernovae. Evidence strongly suggests that they occur when a white dwarf collects too much mass, triggering a nuclear explosion that completely destroys the white dwarf. Although astronomers have seen many systems where a white dwarf is collecting matter, none seemed to have the right conditions to lead to a Type Ia supernova. For example, some white dwarfs are collecting matter at too low a rate to get to the critical mass in the universe's lifetime. The properties of the shock wave observed around RS Ophiuchi allowed Sokoloski's team to calculate the mass of the white dwarf that produced it. They determined it is very close to the critical mass that would trigger a supernova. That led them to suggest that systems like RS Ophiuchi, called recurrent novae, account for at least some of the Type Ia supernovae. If true, this would help solve the mystery of their origin and could help refine the distance scale they underpin. "It would be very nice to explain why there is this slight variation in supernova brightness," Sokoloski told New Scientist. Lack of hydrogen But there is a problem with this idea, argues Sumner Starrfield of Arizona State University in Tempe, US, who is also studying RS Ophiuchi's recent outburst. Type Ia supernovae are distinguished by a lack of hydrogen in their blast waves, he says, and the red giant in the RS Ophiuchi system has shed a lot of hydrogen into the surrounding area. "I think it will explode as a supernova but it's not going to be a Type Ia," Sumner told New Scientist. Sokoloski argues that the white dwarf's recurrent outbursts have probably removed the hydrogen from the immediate vicinity, so that it would not appear in a future Type Ia blast wave. A second study released on Wednesday shows that the material from the explosion seen in February was probably spewed out in jets rather than equally in all directions. Tim O'Brien of the Jodrell Bank Observatory in Macclesfield, UK, led the study. It was based on radio data from the UK's Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). "It's a jet-like explosion, probably shaped by the geometry of the binary-star system at the centre," says O'Brien. "This suggests that there is much more going on than we believed," says Sumner. He added that it will probably take years to figure all out the implications of the new information. Journal reference: Nature (vol 442, p 276, 279) __________________________________________________________________ Mystery of Explosive Star Solved Ken Thar for space.com July 19, 2006 Source Link In February, a faint star a few thousand light-years away flared suddenly, beaming so brightly that for a few days it was visible to the naked eye. The star is a stellar corpse the size of Earth, known as a white dwarf, and it is paired in a binary system with a red giant, a dying, bloated star that once resembled our Sun. The red giant has been dumping gas onto the surface of the white dwarf, and every few years, enough matter accumulates to set off a giant thermonuclear explosion. It was one of these explosions, called a "nova," that astronomers and stargazers detected earlier this year. The two-star system, called RS Ophiuchi, is known as a recurrent nova because five similar eruptions have been detected before. The first observation occurred in 1898; the last eruption prior to this latest one happened in 1985. The new observations, made using advanced radio and X-ray telescopes not available during the last outburst, reveal the explosion to be more complex than was previously assumed. Standard computer models had predicted a spherical explosion with matter ejected in all directions equally. The latest observations instead showed that the explosion evolved into two lobes, confirming suspicions that the nova outburst produces twin jets of stellar material that spews out from the white dwarf in opposite directions. "The radio images represent the first time we've ever seen the birth of a jet in a white dwarf system. We literally see the jet 'turn on,'" said Michael Rupen, an astronomer at the National Radio Astronomy Observatory who studied RS Ophiuchi using the Very Long Baseline Array (VLBA). As impressive as the nova are, they might just be precursors for a more violent supernova explosion that will occur in the future, scientists say. Like the Sun, Only More Powerful The white dwarf's thermonuclear blasts are similar to those that occur on the surface of the sun, but they can be over 100,000 times more powerful. During each outburst, an amount of gas equal to the mass of the Earth is flung into space. Some of this ejected matter slams into the extended atmosphere of the inflated red giant, creating blast waves that accelerate electrons to nearly the speed of light. As the electrons travel through the stars' magnetic fields, they emit radio waves that can be detected by telescopes on Earth. The blast waves move at over four million miles (about 6.4 million km) per hour. For a few weeks during each outburst, the white dwarf becomes a red giant. "After the [thermonuclear explosion], the white dwarf will puff up into a red giant for a few weeks as the hydrogen that has been blasted into space fuses into helium," explains Richard Barry of the NASA Goddard Space Flight Center in Maryland. All eyes on Ophiuchi Japanese astronomers first detected signs of RS Ophiuchi's latest nova on the night of Feb. 12. Follow-up observations by radio telescopes revealed an expanding blast wave whose diameter was already the size of Saturn's orbit around the Sun. In the weeks following, several radio and X-ray telescopes around the world tracked RS Ophiuchi closely, including the MERLIN array in the UK, the European EVN array, the Very Long Baseline Array (VLBA) and Very Large Array (VLA) in the United States, and NASA's Swift and Rossi X-ray Timing Explorer satellites. Findings from the Rossi X-ray Timing Explorer and the VLBA/EVN observations are detailed in two separate studies published in the July 20 issue of the journal Nature. The red giant and white dwarf stars making up RS Ophiuchi are separated by about 1.5 astronomical units, or one and a half times the distance the Earth is from the sun. The binary star system is located in the constellation Ophiuchus, about 5,000 light-years away

any volunteers?

Kevin You've been a ray of sunshine here. You are always upbeat and have something positive to say. Your presence here has enriched us all. JS

OK. Two cats. Check. I'm liking you better already. Now for your boy friend: is the teasing friendly and good natured or malicious and demeaning? Either way it seems to be bothering you. Talk to him about it. Unless he is a jerk that is being intentionally mean, he will be considerate of your feelings and stop. Now- if he is being intentionally mean, kick the *&^%% to the curb! Don't stay with someone who is mean to you! This is how abusive relationships happens. MANY people stay with someone who is bad for them because of low self-esteem and insecurity. Worse, they stay with an abusive partner because they don't think that they can do better or don't deserve any better. You can do better and you deserve better! Soooo... he's not a jerk and you're keeping him? It sounds like the two of you need to develop some common interests. Take a class. Volunteer- something that the two of you can do together. This will help your relationship in a number of ways and add new dimensions to it. Boredom often masks other problems. What some people call boredom is really anxeity, worry or depression. Is something else on your mind?

Eric is legal now!!!! Woo-hoo! :king:

May your 17th year be your best yet!

Xander is lucky to have you! You pay attention to him, walk him and play with him. Way too many people just put their dogs in the back yard and don't give them enough attention. Then when they act up, they say stupid dog when it's really a stupid owner.

Hi Vance! Glad to hear that your blood pressure is under control. My doctor always seems disappointed when my blood pressure is so normal since I could lose 20 pounds and smoke camels. Blood pressure can be greatly effected by nerves. If you were stressed out when they took it, it could have skewed the reading toward the high side. You're way too young for high blood pressure. You are supposed to be over forty, 20+ pounds overweight and smoke camels to have high blood pressure. You could get in trouble with our Union! JS

In my old age I don't have that distraction problem. I'm real nearsighted and with my glasses, I can only see directly in front. It's kinda like wearing blinders like they put on plow mules. Downside is that if I look at someone, I look directly at them. None of those coy out-of-the-corner of my eye looks for me. I don't recommend it- becoming very near sighted that is.

Beautiful Skin was hot but the subject matter creeped me out. :wacko: If he is gay, then w00t!- welcome to the family Joey!!!

I hate to rain on the Parade but Lance bass doesn't strike me as being smart enough to be gay. There is an IQ requirement you know. In that picture, he looks like a doofus.

get a cat. you'll never be bored again.

Anybody notice that I had posted this to the e-fiction gadget?

I couldn't decide which of the two pups in the video was the cutest.

Any time Amico Mio. Just look out for the fat kitty while you are sleeping on the sofa. He likes to jump on the sofa in the dark and look out the window. The person below me is dreading Monday.

Thanks for all of your comments and votes in the poll! Keep them coming and tell us about any technical issues you may have. I would also like to hear from some of our dial-up users: how does the site perform at low speeds?