Thursday, March 15, 2012
In related news...
I referenced a song in that last post- I know, but I couldn't resist. Just thought I'd link it here; it's amusing.
Wednesday, March 14, 2012
The Sun (Is a Miasma of Incandescent Plasma)
Welcome back, hypothetical reader! Had enough of black holes? Yes? Good. No? Too bad, we're talking about the sun now. Why the sun? Because the sun is interesting. We've discussed stars, their fusion processes, and soon we'll be discussing their deaths. But why not discuss stars on a different level, looking at their physical structure, and their layers. That's what we'll be doing today.
First, the basics. The sun has a mass of 1.9891*10^30 kilograms, 333000 times that of the Earth (5.9736*10^24 kg) and a radius of 6.955*10^5 kilometers, 109 times that of the Earth (6731 km). That's pretty huge, but relative to other stars, it is only average. As we discussed in class today, the stars that go supernova can be ten or even one hundred times larger than the sun, while white dwarfs can have the sun's mass but be no larger than the earth.
Of course, today, we're not discussing types of stars, we're talking about that one, very important star in the middle of our solar system. More specifically, I'll now be talking about the parts of the sun. You see, the sun is split up into several layers- the core, the radiation zone, the convection zone, the photosphere, the chromosphere, the transition region, and the corona.
First, the core. The core is the extremely dense region at the center of the star, where nuclear fusion occurs, powering the sun. The core, which is fifteen thousand degrees kelvin on average, is so intensely hot that the hydrogen and helium atoms in it are completely stripped of their electrons. The result is a state of matter referred to as plasma, which is the most energetic state of matter, and is separate from the other three states of matter. Hence, "The Sun is a Miasma of Incandescent Plasma," as opposed to being a "Mass of incandescent gas," as was previously believed.
The layer above the core, who's thickness takes up most of the sun's radius, is the radiation zone. This zone contains much of the star's unfused hydrogen, and it's only real purpose is, as it's name suggests, to radiate the sun's energy. As we've discussed, it takes huge amounts of time for light released by the sun's core to radiate outward, and much of that process takes place in this layer. In this stage, photons are rapidly released, absorbed by hydrogen atoms, and released again. Eventually, these photons work their way to the surface.
Next is the convection zone. We've discussed previously that in medium and larger stars, hot hydrogen "bubbles" can rise from the lower layers to the surface of the sun, acting as an alternate way for the sun to radiate energy.
"Photosphere" is really just a fancy thing to call the surface of the sun. Once light reaches the photosphere, it is able to radiate away, without being interrupted by being absorbed and redirected again. The temperature at this layer is around six thousand kelvin.
Above the surface of the sun is a thin layer called the chromosphere. This area contains scattered gasses, which cause the absorbtion lines visible in sunlight.
The outermost layer of the sun is the corona, literally "halo" in Latin. This layer is by far the hottest layer of the sun, with temperatures ranging in the millions of kelvin. The gasses in this layer are carried by solar wind throughout the solar system, barraging planets in radiation- the result of which on our planet is the auroras.
Here is an image that may clear up the orientation and relative sizes of the layers.
Hopefully this gives some interesting detail and a good look into the interior of the sun. I felt that this would be of interest, as we discussed how stars work, form, and die, but spent relatively little time looking closely at the stars themselves.
Until next time, happy astronomy!
Sources-
http://www.spacestationinfo.com/layers-sun.htm
http://www.universetoday.com/wp-content/uploads/2008/09/solarinterior.jpg
http://en.wikipedia.org/wiki/The_sun
First, the basics. The sun has a mass of 1.9891*10^30 kilograms, 333000 times that of the Earth (5.9736*10^24 kg) and a radius of 6.955*10^5 kilometers, 109 times that of the Earth (6731 km). That's pretty huge, but relative to other stars, it is only average. As we discussed in class today, the stars that go supernova can be ten or even one hundred times larger than the sun, while white dwarfs can have the sun's mass but be no larger than the earth.
Of course, today, we're not discussing types of stars, we're talking about that one, very important star in the middle of our solar system. More specifically, I'll now be talking about the parts of the sun. You see, the sun is split up into several layers- the core, the radiation zone, the convection zone, the photosphere, the chromosphere, the transition region, and the corona.
First, the core. The core is the extremely dense region at the center of the star, where nuclear fusion occurs, powering the sun. The core, which is fifteen thousand degrees kelvin on average, is so intensely hot that the hydrogen and helium atoms in it are completely stripped of their electrons. The result is a state of matter referred to as plasma, which is the most energetic state of matter, and is separate from the other three states of matter. Hence, "The Sun is a Miasma of Incandescent Plasma," as opposed to being a "Mass of incandescent gas," as was previously believed.
The layer above the core, who's thickness takes up most of the sun's radius, is the radiation zone. This zone contains much of the star's unfused hydrogen, and it's only real purpose is, as it's name suggests, to radiate the sun's energy. As we've discussed, it takes huge amounts of time for light released by the sun's core to radiate outward, and much of that process takes place in this layer. In this stage, photons are rapidly released, absorbed by hydrogen atoms, and released again. Eventually, these photons work their way to the surface.
Next is the convection zone. We've discussed previously that in medium and larger stars, hot hydrogen "bubbles" can rise from the lower layers to the surface of the sun, acting as an alternate way for the sun to radiate energy.
"Photosphere" is really just a fancy thing to call the surface of the sun. Once light reaches the photosphere, it is able to radiate away, without being interrupted by being absorbed and redirected again. The temperature at this layer is around six thousand kelvin.
Above the surface of the sun is a thin layer called the chromosphere. This area contains scattered gasses, which cause the absorbtion lines visible in sunlight.
The outermost layer of the sun is the corona, literally "halo" in Latin. This layer is by far the hottest layer of the sun, with temperatures ranging in the millions of kelvin. The gasses in this layer are carried by solar wind throughout the solar system, barraging planets in radiation- the result of which on our planet is the auroras.
Here is an image that may clear up the orientation and relative sizes of the layers.
Hopefully this gives some interesting detail and a good look into the interior of the sun. I felt that this would be of interest, as we discussed how stars work, form, and die, but spent relatively little time looking closely at the stars themselves.
Until next time, happy astronomy!
Sources-
http://www.spacestationinfo.com/layers-sun.htm
http://www.universetoday.com/wp-content/uploads/2008/09/solarinterior.jpg
http://en.wikipedia.org/wiki/The_sun
Monday, March 12, 2012
Black Holes- Sucking Us Back In
Next day, two weeks later, same thing. Got pretty sick there for a while, so it'll take some doing to get caught up, but what can you do.
As I said last time, I'll be continuing on the topic of black holes- Namely, how we detect them. So, how do you detect something that is quite literally invisible? Ordniarily, we see things that reflect or refract light, but black holes, as we discussed, pull light in and don't let it back out. So how do we find them?
There are actually more ways to detect a black hole than you would think. One way was what I discussed previously- quasars. As I mentioned previously, quasars are superheated disks for gas and particulate quickly circling a black hole. Their extreme heat causes them to radiate significantly, so these are actually relatively easy to locate by testing the spectrum given by a radiator, looking for large amounts of x-ray and radio waves. The process in which the quasars is referred to as "accretion," and releases huge amounts of energy relative to the amounts of matter involved- as much as fourty percent of the mass' equivalent in energy is released. Along with quasars are frequently another phenomenon, referred to as "jets." These jets are massive releases of x-rays, which are released in pulses at a right angle to the plane of the quasar. Not much is known about the process by which jets are created, but they are easily observed, and are a good way to find large black holes.
Bear with the video, the quasar and jets show up about halfway through.
Well, finding black holes because they have visible formations around them is well and good, but there are plenty of black holes that don't have quasars. How do we spot those? Well, one solution is to look for gravitational lensing. You remember that, right? Of course you do. It stands to reason, since high-mass objects such as large stars and galaxies can gravitationally lens light around them, black holes, being so massive, can do the same. By searching for instances of gravitational lensing that don't appear to have an object to lens around, you can find black holes.
A third method, and the last I'll discuss, is probably the simplest. This method consists of simply observing stars in an area where it is believed a black hole may exist, and watching the movement of these stars. Their motion can often act as a clue to an invisible large mass, which it is probably orbiting. This is an especially useful method for detecting smaller black holes, those without quasars and jets, and those black holes that are scattered throughout the galaxy instead of occupying its center. This case can also apply in the rare cases where black holes form binaries with stars.
Hopefully this expands your knowledge of black holes, as this is my second post on the topic. Until my next post, happy astronomy!
As I said last time, I'll be continuing on the topic of black holes- Namely, how we detect them. So, how do you detect something that is quite literally invisible? Ordniarily, we see things that reflect or refract light, but black holes, as we discussed, pull light in and don't let it back out. So how do we find them?
There are actually more ways to detect a black hole than you would think. One way was what I discussed previously- quasars. As I mentioned previously, quasars are superheated disks for gas and particulate quickly circling a black hole. Their extreme heat causes them to radiate significantly, so these are actually relatively easy to locate by testing the spectrum given by a radiator, looking for large amounts of x-ray and radio waves. The process in which the quasars is referred to as "accretion," and releases huge amounts of energy relative to the amounts of matter involved- as much as fourty percent of the mass' equivalent in energy is released. Along with quasars are frequently another phenomenon, referred to as "jets." These jets are massive releases of x-rays, which are released in pulses at a right angle to the plane of the quasar. Not much is known about the process by which jets are created, but they are easily observed, and are a good way to find large black holes.
Well, finding black holes because they have visible formations around them is well and good, but there are plenty of black holes that don't have quasars. How do we spot those? Well, one solution is to look for gravitational lensing. You remember that, right? Of course you do. It stands to reason, since high-mass objects such as large stars and galaxies can gravitationally lens light around them, black holes, being so massive, can do the same. By searching for instances of gravitational lensing that don't appear to have an object to lens around, you can find black holes.
A third method, and the last I'll discuss, is probably the simplest. This method consists of simply observing stars in an area where it is believed a black hole may exist, and watching the movement of these stars. Their motion can often act as a clue to an invisible large mass, which it is probably orbiting. This is an especially useful method for detecting smaller black holes, those without quasars and jets, and those black holes that are scattered throughout the galaxy instead of occupying its center. This case can also apply in the rare cases where black holes form binaries with stars.
Hopefully this expands your knowledge of black holes, as this is my second post on the topic. Until my next post, happy astronomy!
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