What do stars radiate?
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Nature is all about entropy or conservation of energy.  Stars of which Our Sun is one start their life as large balls of Hydrogen gas.  Due to the friction of the untold number of molecules  moving about, heat is developed- just like rubbing Your hands together.  The inside temperature of the Sun is about 2 million degrees.  It takes more energy to maintain 4 atoms of hydrogen than it does for one Helium.  With all the heat in the star's core it is possible for the hydrogens to form a helium by the process of nuclear fusion.  6 hydrogens take part in the reaction but two are recovered so the net result is 4h>1He.  This reaction results in the saving of 0.6% energy which works its way to the surface and radiates out into space.  Within the Sun it is estimated that about 745,000 tons of H are converted every second.  This number varies a bit when one reads the literature, but whatever the actual number is it is huge.
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There are a lot of red stars in space. From Nasa's web site: "There are many normal red stars near the Sun, with temperatures of a few thousand degrees and masses much less than that of the Sun. None, however, is bright enough to be seen without a telescope. All of the bright red stars in the night sky are red giants and supergiants, counted among those we term abnormal stars. Examples are the supergiants Betelgeuse in Orion and Antares in Scorpius (each about 520 light years from Earth) and giant Aldebaran (68 light years) in Taurus."
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check this site...\nhttp://www.bbc.co.uk/science/space/stars/index.shtml
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all stars are formed from nebulae (the plural of nebula). Nebula is a term for a cloud of gas, and stars form from gas. Stars more massive than ~ 6 solar masses are expected to supernova, stars less massive than this (like our Sun, of course) become white dwarfs. After a supernova, there may be nothing left, or there could be a remnant: either a neutron star or a blackhole. If the remnant is more massive than around 3 solar masses it will probably end up as a blackhole. Stars are smallest when they are burning hydrogen into helium, which is what stars do during most of their lifetimes. Stars in this stage are sometimes called dwarfs. There are also two other kinds of "dwarfs": white dwarfs are burned-out stars mentioned above (the Learning Center has more info on these), and brown dwarfs are stars which never accumulated enough mass to start burning hydrogen.
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Not necessarily.  A star is only a sun if it has planets around them.  But all stars look like suns.
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They are called black dwarfs, and they do emit some radiation, but it would be next to impossible to sort it from the background radiation noise since it would be in the far infrared.  Blackbody radiation occurs by a perfect absorber/emitter, and black dwarfs are not this.  They are called black dwarfs because of the amount of radiation they emit makes them essentially "invisible" to any type of detector.  They are theorized to have an internal temperature in the hundreds to low thousands of celsius, quite far from the internal temperatures of main sequence stars.\n\nThe only way we could even see them would be by their gravitational influence on light passing by the black dwarf from stars in their background.  Only then, using a wide detector and via photometry, would be even to begin to see this object.  Luckily, we can estimate its mass based on the amplification via gravitational microlensing and the formulas associated.  This is what I did my senior thesis on :)\n\nBy the way, black dwarfs shouldn't be around yet anyway.  No star has cooled enough to be even considered "black" (brown, yes, but not black).
511957
When a star die, it may become a white dwarf or cause a supernova explosion according to there masses.If a star is more than chandra limit (1.44times the sun mass)the outer envelope increases in size due to loss of energy.the inner core still shrinks under the imbalanced force of gravity.the force increases to such an effect that the electrons are also sucked in the nucleus and the star is now composed of protons only.hence it emits radio waves called pulsar and the star is called a neutron star.
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The best way to compare other stars to the sun is to talk in terms of\n\nTheir size: how many solar diameters are they?\nTheir mass: how many solar masses are they?\nTheir brightness: how does their luminosity compare to the sun = 1?\n\nMorgan-Keenan spectral classification\nThis stellar classification is the most commonly used. The common classes are normally listed from hottest to coldest (with mass, radius and luminosity compared to the Sun) and are: \n\nClass Temperature Star colour Mass Radius Luminosity \nO 30,000 - 60,000 K Bluish ("blue") 60 15 1,400,000 \nB 10,000 - 30,000 K Bluish-white ("blue-white") 18 7 20,000 \nA 7,500 - 10,000 K White with bluish tinge ("white") 3.2 2.5 80 \nF 6,000 - 7,500 K White ("yellow-white") 1.7 1.3 6 \nG 5,000 - 6,000 K Light yellow ("yellow") 1.1 1.1 1.2 \nK 3,500 - 5,000 K Light orange ("orange") 0.8 0.9 0.4 \nM 2,000 - 3,500 K Reddish orange ("red") 0.3 0.4 0.04 \n\nThese classes are further subdivided by Arabic numerals (0-9). A0 denotes the hottest stars in the A class and A9 denotes the coolest ones. The sun is classified as G2.\n\nSpectral types\n\nClass O\nClass O stars are very hot and very luminous, being bluish in colour; in fact, most of their output is in the ultraviolet range. These are the rarest of all main sequence stars, constituting as few as 1 in 32,000. O-stars shine with a power over a million times our Sun's output. \n\nExamples: Zeta Puppis, Epsilon Orionis \n\nClass B\nClass B stars are extremely luminous and blue. As O and B stars are so powerful, they live for a very short time. They constitute about 0.13% of main sequence stars -- rare, but much more common than those of class O.(\n\nExamples: Rigel, Spica \n\nClass A\nClass A stars are amongst the more common naked eye stars. As with all class A stars, they are white or bluish-white. They comprise perhaps 0.63% of all main sequence stars.\n\nExamples: Vega, Sirius \n\nClass F\nClass F stars are still quite powerful but they tend to be main sequence stars. Their colour is white with a slight tinge of yellow. These represent 3.1% of all main sequence stars.\n\nExamples: Canopus, Procyon \n\nClass G\nClass G stars are probably the best known, if only for the reason that our Sun is of this class. Supergiant stars often swing between O or B (blue) and K or M (red). While they do this, they do not stay for long in the G classification as this is an extremely unstable place for a supergiant to be. These are about 8% of all main sequence stars. \n\nExamples: Sun, Capella \n\nClass K\nClass K are orangish stars which are slightly cooler than our Sun. Some K stars are giants and supergiants, such as Arcturus while others like Alpha Centauri B are main sequence stars.  These make up some 13% of main sequence stars.\n\nExamples: Arcturus, Aldebaran \n\nClass M\nClass M is by far the most common class if we go by the number of stars. All the red dwarfs go in here and they are plentiful; over 78% of stars are red dwarfs, such as Proxima Centauri. M is also host to most giants and some supergiants such as Antares and Betelgeuse, as well as Mira variables. \n\nThe red color is deceptive; it is because of the dimness of the star. When an equally hot object, a halogen lamp (3000 K) which is white hot is put at a few kilometers distance, it appears like a red star.\n\nExamples: Betelgeuse, Barnard's star \n\nSpectral types for rare stars\nA number of new spectral types have been taken into use for rare types of stars, as they have been discovered:\n\nW: Up to 70,000 K - Wolf-Rayet stars. \nL: 1,500 - 2,000 K - Stars with masses insufficient to run the regular hydrogen fusion process (brown dwarfs). Class L stars contain lithium which is rapidly destroyed in hotter stars. \nT: 1,000 K - Cooler brown dwarfs with methane in the spectrum. \nC: Carbon stars. \nR: Formerly a class on its own representing the carbon star equivalent of Class K stars, e.g. S C
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In order to measure the diameter of a star you really need three pieces of information about the star (1) distance (2) brightness (3) and color.\nStep 1: Scientists can figure out the total power output of the star by knowing its brightness at Earth and its distance. \n\nStep 2: Figure out the surface temperature. The universe really gave scientists a lucky break because stars are fairly predictable objects. What I mean is that, for most stars once a scientist know one property of the star they can generally figure out everything else they want to know about it. This is because stars behave like "black bodies". This is a physics term which describes how an object of certain temperature glows at different wavelength (thus influencing its color). Most ordinary matter resembles a black body (has nothing to do with being black, it's just terminology). You probably already have an intuitive understanding of this from your everyday experience. For example, when you heat up an object, at first it might start to glow red. And as it gets hotter it might start to glow yellow, blue, and eventually white. Because stars approximate black bodies very well, by knowing the color of the star scientist can figure out what its surface temperature is quite accurately. \n\nStep 3: Another great thing about black bodies is that, for any specific amount of surface area astronomers can predict exactly how much light it will radiate (hotter objects are brighter). And since they already know the temperature and the total brightness of the star they can figure out its surface area, and thus it's diameter :)
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None, they up in the Sky, best seen at night. The Earth does revolve around a Big Star that can actually be seen in the day and not night. Make for a good Word Play/Riddle question. ;-D
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The burned out centre of a low mass star is a white dwarf. It's a hot ball of carbon and oxygen, though too cool for thermonuclear reactions to occur. They're about the size of Earth and are too dim to be seen with the naked eye.
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The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere. \n\nStars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling). \n\nStars closer to the horizon appear to twinkle more than stars that are overhead - this is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction. Also, planets do not usually twinkle, because they are so close to us; they appear big enough that the twinkling is not noticeable (except when the air is extremely turbulent). \n\nStars would not appear to twinkle if we viewed them from outer space (or from a planet/moon that didn't have an atmosphere). \n\n\n---------------------------------------------------------------------------------\nStars, except for the Sun, although they may be millions of miles in diameter, are very far away.  They appear as point sources even when viewed by telescopes.  The planets in our solar system, much smaller than stars, are closer and can be resolved as disks with a little bit of magnification (field binoculars, for example).\n\nSince the Earth's atmosphere is turbulent, all images viewed up through it tend to "swim."  The result of this is that sometimes a single point in object space gets mapped to two or more points in image space, and also sometimes a single point in object space does not get mapped into any point in image space.  When a star's single point in object space fails to map to at least one point in image space, the star seems to disappear temporarily.  This does not mean the star's light is lost for that moment.  It just means that it didn't get to your eye, it went somewhere else.\n\nSince planets represent several points in object space, it is highly likely that one or more points in the planet's object space get mapped to a points in image space, and the planet's image never winks out.  Each individual ray is twinkling away as badly as any star, but when all of those individual rays are viewed together, the next effect is averaged out to something considerably steadier.\n\nThe result is that stars tend to twinkle, and planets do not.  Other extended objects in space, even very far ones like nebulae, do not twinkle if they are sufficiently large that they have non-zero apparent diameter when viewed from the Earth.\n-------------------------------------------------------------\n\n\nI can be more specific, sure. Remember that just like a computer screen, your eye is composed of a certain number of "pixels," each represented by a single light-receptor cell in your retina. If two (or more) points of light are close enough such that they are focused on the same receptor cell in your eye, you will experience them as a single point of light. This is referred to as the "resolution" of your eye, or any telescope for that matter. \n\n\nNow, a star on the sky is in a true sense a single point of light. All the light comes through the atmosphere in exactly the same direction, through exactly the same atmospheric turbulence, and thus is bent in exactly the same way. So when it gets to your eye, the amount of light you see coherently varies. It also strikes (primarily) only a single receptor in your eye. \n\n\nOn the other hand, light from a planet is different. Each of a few receptors in your eye sees a large number of light rays coming f
534669
After a star dies, there is still some residual heat left over. That heat makes the star (white dwarf or neutron star) glow, even though it is not producing any energy. Eventually, the star cools off and does indeed simply become a hunk of ash, which we call a "black dwarf." \n\npeace
37735
Stars are like our Sun. Not comets at all. Comets are dirty, big snowballs that have no light at all. The twinkling comes from heat radiating from earth which makes the light spectrum shift in different colours. Symbols that represent something doesn't often look like the original. Take the symbol for a heart for example. But it's easy! :) Try to draw a immensly huge boiling, burning piece of gas that throws tons of particles out from it in lightning speed and see if anyone understands what you drew. Now try to make it into a character that you can type on a keyboard :)
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Not a simple question, but  this is two main reasons.\n\n1) Brightness of the Star Play a part.   Assume uniform Atmosphere.\n\n2) The Atmosphere also another part.  Assume stars of the same brightness.\n\n1)  Brightness of the Star Play a part.\nBrighter the Star, less likely the twinkle.   Look at the Moon, does it go Bink Bink?  Too Bright.\n\nBut Dimer stars, under the same Atmospheric conditions, may Bink.\n\n2) The Atmosphere also another part.\nThe Atmosphere is not uniform, look at the sky during the day, sometime, it clear blue,  and other time clouds mass abound.\n\nThe Atmosphere is like a thin soup, with some sliver of bread in it,.  using that example, when the Stars of the same brightness is in the Sky,  imagine when a sliver of bread blocks lightly one of the stars, thus one Bink, and another don't.\n\nIt Real life, Stars are not of the same brightness, and the Atmosphere is not always uniform.  making the issue complex.
689695
All stars are made mostly of hydrogen, with a reasonable amount of helium thrown in for good measure.  Trace other elements exist as well, and since astronomers are so biased toward the light stuff (hydrogen and helium are the smallest atoms and therefore the lightest elements), they refer to anything heavier than helium as a “metal.”  The proportion of a star made up of stuff heavier than helium is called its “metallicity.”  The Sun’s metallicity is about 1.6% by mass.\n\nIn galactic terms, the Sun is considered “new.”  Yeah, it’s some 4.5 billion years old, but the same way anything heavier than helium gets dubbed a metal, the Sun is considered new—because it’s a second- (or maybe third-) generation star.\n\nY’see, when the Universe formed, hydrogen and helium were pretty much the only game in town, plus a bit of deuterium or lithium.  A star forming out of this stuff could have a metallicity just one millionth of the Sun’s!  To get more “metals,” the first generation of stars (i.e., the old ones) had to form, cooking up heavier elements inside their thermonuclear cores.  Some fraction of those stars went kablooie (in the form of supernovae and other exotic events), enriching the interstellar medium with heavy elements.  \n\nWhen a second (or third) generation of stars formed from this enriched interstellar medium, they had much higher metallicities.\n\nWe can find evidence for the presence of “metals” when we look at the light from individual stars or even entire galaxies.  Those elements show up as absorption features at very particular wavelengths of light, and astronomers can read that collection of “absorption lines” like a fingerprint.\n\nSo when we look at elliptical galaxies, we see evidence for very few elements heavier than helium, so we infer that the stars are “old”; when we look at most spiral galaxies, we see evidence for a metal-rich environment, so we understand the stars to be “new,” in the sense that they are second-generation stars that have benefitted from their predecessors” nuclear fusion and element production.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
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First, our sun has a long time to go before it could possibly become a supernova, not for billions and billions of years, so don't worry about it, if you were worrying. OK?\n\nNow, the way a star burns is by fusion, which is building up heavier elements by fusing atoms of lighter elements together. The typical start starts out as hydrogen, and it fuses the hydrogens together into helium. \n\nWhat happens when a star runs out of hydrogen? It starts fusing the heliums together into heavier elements. In order to begin this process, the star has to contract, to squeeze everything together to make the core temperature hotter. \n\nNotice that when the star began to run out of hydrogen, it cooled off a little. So the temperature of the star fluctuates. Its size fluctuates too, since the heat energy partly counteracts the gravity that holds it together.\n\nSo, the star cools off a little, it contracts, and we call this a pulsating or variable star. (This is somewhat of an oversimplification; there are different types of variable stars. But I am ignoring them for purposes of this illustration.) Then the star begins fusing helium, and heats up again. The star expands. \n\nThe outer surface of the star explodes away in what we call a nova-- not a supernova, yet. Some of the gas rushes away and may form what is called a nebula, a cloud. some of thee nebulas give off pretty colors, because, just like a neon sign, the gas in them is excited by the energy of the star and glows.\n\nSo, after repeated cycles of this, and bazillions of years, the star is exhausted. When the star gets iron in its core, there is no turning back. You can't fuse iron into anything. \n\nBut, you say, what about those elements that are heavier than iron, like gold and mercury and uranium? Ah, I'm so glad you asked about that. That is where the supernova comes in. \n\nA supernova is the death of a star. A nova flares up and puts out lots of energy, but the supernova puts out as much energy as the star might have put out over its entire lifetime! The last time there was a supernova in our galaxy (the Crab Nebula was formed) in 1054 AD. The Chinese were the only ones whe were doing much astronomical observation then. \n\nBut it was visible in broad daylight! From LIGHT YEARS away!\n\nWhat happens is this: the star begins to contract one final time. Most of the star blows away, making a really, really impressive nebula. All the elements that were built up in the final explosion-- all the heavy elements beyond iron-- get flung out into space, where they might meet with other elements and form planets and things.\n\nWhat happens to the rest of the star? One of three things, depending on how big it is. If it is little, it may form a white dwarf, a little star that is not so big but is now mostly hydrogen and helium and will last a long time. I think they are supposed to expand into red giants when they are about to burn out, but I don't remember for sure. \n\nIf the star is medium sized, it may become a neutron star. It is no longer buring with fusion like a regular star. The nuclear particles in its core are squeezed together so that protons and electrons have lost their identities and everything is neutrons. This is as solid and dense as matter can get, neutronium. It has an incredibly strong magnetic field, bazillions of times anything on earth.\n\nThe star's axis of rotation may not line up with the magnetic poles (just the way Earth's magnetic poles are not right at the true north and true south poles.) If this hapens, and the magnetic poles are pointed in the right direction, then every time it points our way, we see a little 'flash' of magnetic energy, and we call these 'pulsars'. The first time anybody detected them, they thought they were radio signals from people in space, because they were so regularly-spaced. It is a good thing there are no pulsars near Earth, because the flashes of intense magnetic fields would fry us lik