APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
Because that will hurt badly. 
8) BY the way, can i have some of those powder that reduce the head size. I will certainly need it when i meet you know who on the other side. 
Yeah, I know who ... Bill Monroe.Doum wrote:... when i meet you know who on the other side.
APODAbstract: We present a high-resolution spectral analysis of Betelgeuse (M2 Iab). Between 1998 January and 1999 March four spatially resolved raster scans (http://cfa-www.harvard.edu/cfa/ep/press ... l0100.html) have been obtained with the STIS on the Hubble Space Telescope. The near-UV echelle spectra reveal double-peaked permitted emission lines of neutral and singly ionized metals, with self-absorbed line cores. We observe reversals in the intensity of both emission line components when scanning across the UV disk, for four unsaturated lines of Si I, Fe I, Al II], and Fe II. We model the Si I lam2516 resonance line with detailed non-LTE radiative transport calculations in spherical geometry, and constrain the mean velocity structure in the projected aperture area, for each scan position on the chromospheric disk. We infer the spatial velocity structure of Betelgeuse's extended chromosphere, which reveals localized upflows in the western front hemisphere in 1998 September, that expand further toward the eastern hemisphere in 1999 March. The spatial scans exhibit simultaneous up- and downflows across the lower chromosphere with mean velocities of ~2 km/s. We infer non-radial (or non-coherent) mass movements during certain phases of the stellar variability cycle from these subsonic flows. We present a discussion of constructing semi-empiric models for the chromosphere of this cool supergiant, and of its temporal variability.
It's happened before...perhaps not without consequences.mark swain wrote:This star is as big as the orbit of Jupiter. At 427 light years, Will it just be nice light show or am I back to digging the shelter in the back yard again if it goes Nova? I saw a program on Super Nova , They said this Betelgeuse Could go any minute.
Betelguese is not a red giant. It is a very massive red supergiant. There is quite a difference.
you expect him to be on site, dont youbystander wrote:BTW: Did you see the lunar impact?
Just a light show. It is much too far away to send significant dangerous radiation our way. The situation would be different if its rotational axis were lined up with Earth, since a gamma ray burst associated with a supernova at that distance could be devastating. But we aren't along that axis, so no worries.mark swain wrote:This star is as big as the orbit of Jupiter. At 427 light years, Will it just be nice light show or am I back to digging the shelter in the back yard again if it goes Nova? I saw a program on Super Nova , They said this Betelgeuse Could go any minute.
Chris Peterson wrote:Just a light show. It is much too far away to send significant dangerous radiation our way. The situation would be different if its rotational axis were lined up with Earth, since a gamma ray burst associated with a supernova at that distance could be devastating. But we aren't along that axis, so no worries.mark swain wrote:This star is as big as the orbit of Jupiter. At 427 light years, Will it just be nice light show or am I back to digging the shelter in the back yard again if it goes Nova? I saw a program on Super Nova , They said this Betelgeuse Could go any minute.
---------------------------------------------------------------http://en.wikipedia.org/wiki/Near-Earth_supernova wrote: .
<<A near-Earth supernova is an explosion resulting from the death of a star
that occurs close enough to the Earth (roughly less than 100 light-years away)
to have noticeable effects on its biosphere.
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. Effects on the planet
Gamma rays are responsible for most of the adverse effects a supernova can have on a living terrestrial planet. In Earth's case, gamma rays induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. In 2009, researchers have found nitrates in ice cores from Antarctica at depths corresponding to the known supernovae of 1006 and 1054 AD, as well as from around 1060 AD. The nitrates were apparently formed from nitrogen oxides created by gamma rays from the supernovae. This technique should be able to detect supernovae going back several thousand years.
. Risk by type
Speculation as to the effects of a nearby supernova on Earth often focuses on large stars as Type II supernova candidates. Several prominent stars within a few hundred light years from the Sun are candidates for becoming supernovae in as little as a millennium. One example is Betelgeuse, a red supergiant 427 light-years from Earth. Though spectacular, these "predictable" supernovae are thought to have little potential to affect Earth.
Recent estimates predict that a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half of the Earth's ozone layer. Such estimates are mostly concerned with atmospheric modeling and considered only the known radiation flux from SN 1987A, a Type II supernova in the Large Magellanic Cloud. Estimates of the rate of supernova occurrence within 10 parsecs of the Earth vary from 0.05-0.5 per Ga to 10 per Ga. Several authors have based their estimates on the idea that supernovae are concentrated in the spiral arms of the galaxy, and that supernova explosions near the Sun usually occur during the ~10 million years that the Sun takes to pass through one of these regions (we are now in or entering the Orion arm). Examples of relatively near supernovae are the Vela Supernova Remnant (~800 ly, ~12,000 years ago) and Geminga (~550 ly, ~300,000 years ago).
Type Ia supernovae are thought to be potentially the most dangerous if they occur close enough to the Earth. Because Type Ia supernovae arise from dim, common white dwarf stars, it is likely that a supernova that could affect the Earth will occur unpredictably and take place in a star system that is not well studied. One theory suggests that a Type Ia supernova would have to be closer than a thousand parsecs (3300 light-years) to affect the Earth. The closest known candidate is IK Pegasi.
. Past events
.
In 1998 a supernova remnant, RX J0852.0-4622, was found in front (apparently) of the larger Vela Supernova Remnant. Gamma rays from the decay of titanium-44 (half-life 90 years) were independently discovered coming from it, showing that it must have exploded fairly recently (perhaps around 1200 AD), but there is no historical record of it. The flux of gamma rays and x-rays indicates that the supernova was relatively close to us (perhaps 600 ly)
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Adrian L. Melott et al. estimated that gamma ray bursts from "dangerously close" supernova explosions occur two or more times per thousand million years, and this has been proposed as the cause of the end Ordovician extinction, which resulted in the death of nearly 60% of the oceanic life on Earth................................................ttp://en.wikipedia.org/wiki/Ordovician wrote:
<<For most of the Late Ordovician, life continued to flourish, but at and near the end of the period there were mass-extinction events that seriously affected planktonic forms like conodonts, graptolites, and some groups of trilobites. Brachiopods, bryozoans and echinoderms were also heavily affected, and the endocerid cephalopods died out completely, except for possible rare Silurian forms. The Ordovician-Silurian Extinction Events may have been caused by an ice age that occurred at the end of the Ordovician period as the end of the Late Ordovician was one of the coldest times in the last 600 million years of earth history.>>
---------------------------------------------------------------http://en.wikipedia.org/wiki/Betelgeuse wrote:
<<A Betelgeuse supernova could easily outshine the Moon in the night sky. It will likely be the brightest supernova in recorded Human history, easily outshining SN 1006. After it explodes, it will likely linger for several months, being visible in the daytime sky and lighting up nighttime skies in the Solar System for a long time, after which the "right shoulder" of Orion will disappear forever.>>
---------------------------------------------------------------http://en.wikipedia.org/wiki/Pelops wrote:
<<In Greek mythology, Pelops (Greek Πέλοψ, from pelios: dark; and ops: face, eye), king of Pisa in the Peloponnesus, was venerated at Olympia, where his cult developed into the founding myth of the Olympic Games. At the sanctuary at Olympia, chthonic night-time libations were offered each time to "dark-faced" Pelops in his sacrificial pit (bothros) before they were offered in the following daylight to the sky-god Zeus.
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Pelops' father was Tantalus, king at Mount Sipylus in Anatolia. Wanting to make an offering to the Olympians, Tantalus cut Pelops into pieces and made his flesh into a stew, then served it to the gods. Demeter, deep in grief after the abduction of her daughter Persephone by Hades, absentmindedly accepted the offering and ate the left shoulder. The other gods sensed the plot, however, and held off from eating of the boy's body. Pelops was ritually reassembled and brought back to life, his shoulder replaced with one of ivory made for him by Hephaestus. Thereafter, all his descendants, the Pelopidae, as a mark of their origin were supposed to have one shoulder as white as ivory. After Pelops' resurrection, Poseidon took him to Olympus, and made the youth his apprentice, teaching him to drive the divine chariot. Later, Zeus threw Pelops out of Olympus, angry that his father, Tantalus, had stolen the food of the gods, given it to his subjects, and revealed the secrets of the gods.
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The shrine of Pelops at Olympia, the Pelopion "drenched in glorious blood" stood apart from the temple of Zeus, next to Pelops' grave-site by the ford in the river. It was enclosed with a circle of stones. Pelops was propitiated at night, with the offering of a black ram. His remains were contained in a chest near the sanctuary of Artemis Kordax, though in earlier times a gigantic shoulder blade was shown; during the Trojan War Pelops' shoulder-blade was brought to Troy by the Greeks because the Trojan prophet Helenus claimed the Pelopids would be able to win by doing so.>>
Here's two different articles on imminent star births of radically different solar masses.mark swain wrote:Interesting info. This star really is huge. Betelgeuse ... Whats the difference in formation to our own? what aloud our sun to not get as big? I saw animated graphics of when our sun switched on ,, they depicted it NOT excepting anymore gas to get lager ,, So why was Betelgeuse aloud to get so big?
Cosmic Cloud Poised to Birth Massive StarA study carried out by two astronomers from the Calar Alto Observatory, in Almeria, and the observatory at the University of Munich, in Germany, has predicted that the dark nebula Barnard 68 will become a shining star in 200,000 years' time. According to the scientists, this nebula is already close to colliding with another, smaller one, in a process that will end with the birth of a star.
...
The astrophysicists Alves and Buerkert suggest that the collision of two gas clouds could be the mechanism that activates the birth of a star. In relation to Barnard 68, they suggest that it is already in an initial unstable state, and that it will collapse 'soon' - within a period of around 200,000 years.
The images they have taken of its density show that B68 is a cold gas cloud with a mass equivalent to that of two suns, but that there is another cloud, 10 times smaller than it (0.2 solar masses), which is getting closer and is 'on the verge' of colliding with it. ...
A massive, tranquil object found lurking in a dark cloud in our galaxy could be about to transform into a massive star or stars, giving astronomers their first glimpse at such a region on the cusp of stellar birth.
The cloud, located near the Aquila rift in the galactic plane 23,000 light-years away, has a mass 120 times that of the sun, but it is all compressed into a volume smaller than the Oort cloud of comets orbiting our solar system ...
That's sort of like asking: Why was Brachiosaurus allowed to get so bigmark swain wrote:This star really is huge. Betelgeuse ... What's the difference in formation to our own? what [allowed] our sun to not get as big? I saw animated graphics of when our sun switched on ,, they depicted it NOT excepting anymore gas to get larger ,, So why was Betelgeuse [allowed] to get so big?
I don't think it's usually a case of what is "allowed". Once a star ignites, it will be producing solar wind and radiation that push away gas and dust, so presumably that will limit its ultimate mass. Its initial mass would seem to be determined by the density of the material in the region it forms in, and the shock dynamics involved in bringing material together.mark swain wrote:Interesting info. This star really is huge. Betelgeuse ... Whats the difference in formation to our own? what aloud our sun to not get as big? I saw animated graphics of when our sun switched on ,, they depicted it NOT excepting anymore gas to get lager ,, So why was Betelgeuse aloud to get so big?
On reading through the Berkeley press release, there is no mention that this shrinkage could indicate Betelgeuse is about to explode. Granted, the 15 year shrinkage is a "mystery" (there's that word again), but the star has been known to vary in size in the past. In fact, it is known to pulsate in size with periods of one and six years. Also, the rotational period of Betelgeuse is once every 18 years; simulations suggest the star is not spherical, so the shrinkage could be an illusion, we are seeing a potato-shaped disk on its thinnest edge.
Despite all these factors, Fox News runs with the title "Nearby Star May Be Getting Ready to Explode." Using the Berkeley press release as a source, and quoting all the facts mentioned above, they've put two and two together, made five and declared stellar Armageddon.
Oh dear.
They've also made their own prediction right at the end:
Yes, it's totally possible Betelgeuse could explode, but the chances of this happening in this 600 year window is highly unlikely, regardless how fast it seems to be shrinking.It's possible we're observing the beginning of Betelgeuse's final collapse now.
If so, the star, which is 600 light-years away, will already have exploded — and we'll soon be in for a spectacular, and perfectly safe, interstellar fireworks show.
These questions are well understood for Type II supernovas. Massive stars are supported against gravitational collapse by the pressure of their fusion. First they fuse their hydrogen; when it is used up, they start to collapse, which raises the temperature enough to fuse helium. When the helium is used up, they collapse some more and heat up enough to fuse carbon. This process continues until Nickel is the product, and beyond this fusion uses more energy than it provides. With nothing left to fuse, the star collapses by its own gravity. The rapid collapse is the source of energy that creates the supernova explosion itself. It can't rejuvenate because there is no fusible material left.harry wrote:What ingnites the star to go supernova?
Where does it get it fuel from if it's dying?
If it has that fuel why does it not rejuvinate?
That isn't a universal pattern. I think what most people would say is that supernovas are not symmetric explosions. Some combination of their rotation, magnetic properties, accretion, jet formation, core element distribution (from convection), and probably other factors results in an asymmetric explosion, which gives the remnant a substantial change of velocity, and can produce a number of odd nebula shapes.How does it form the hour glass image?
The question is if a person in your position can handle a better explanation.harry wrote:Chris a person in your position should give a better explanation than a secondary school explanation.
maybe try this if it is not too simple for you?harry wrote:Where and how do the Neutrons form so quickly?
You asked a few questions, you got a few answers (and correct ones, I'll add).harry wrote:Chris a person in your position should give a better explanation than a secondary school explanation.
They don't form from nothing- they are already part of the stellar material. When a neutron star forms, there is a complex process of separation, transformation, and stratification of particles. AFAIK there is no observational evidence that is very useful for understanding the interior of neutron stars, only mathematical models. It's a complex issue (and one that you did not ask about in your original post).Sometimes a Neutron core remnnant is left behind. Where and how do the Neutrons form so quickly?
I'm glad you know so much more than the scientists who specialize in this. I'm going to stick with their assessment, however. All you need for a Type II supernova is a massive star that can't produce enough pressure from fusion to support its own mass.Although gravity plays a main part. There are other process that are involved and without them the Supernova would not occur.
