Anthony Crehan, #10514
Mr. Constantinides
Science 8, Period 4
April 8, 2014
Quasars and Pulsars
Pulsars and Quasars
Let’s start out at the very bottom; the definitions of a quasar and a pulsar. A quasar consists of a supermassive black hole surrounded by a cloud of dust that allows for focused beams of radiation. Quasars usually are only seen in moderately young galaxies, as they require a large amount of matter, commonly known as “stardust,” to keep the beam going. This energy source has to be extremely compact to give the quasar enough energy to exist. Once this fuel runs out, though, the quasar ceases to be and becomes a normal supermassive black hole. Pulsars, on the other hand, are the remnants of stars that were once ten times the size of our sun. When these stars come to the end of their life, they supernova and leave only a super dense mass called a neutron star or pulsar. These formations are called pulsars because they emit a radio signal and rotate in such a way that it looks as if they are pulsing. Now, it is on to greater things. Let’s get specific with both of these amazing celestial formations.
As was stated earlier, quasars are composed of a supermassive black hole and the cloud of dust feeding it. They are only ever found in new galaxies, as there is enough matter there to keep the quasar fed and producing a signal. In fact, scientists believe that quasars are a partial reason that there aren’t many small, scattered galaxies in the universe. The quasar’s signal will gradually weaken as the quasar’s life goes on and will eventually stop when there is not enough matter to keep the quasar fed. Scientists have never seen the formation of a new galaxy and, therefore, have never seen the actual format...
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... only be seen via X-rays. Hotter areas can be seen more clearly than the cooler areas. Lastly, there are things called Accretion stars. Sometimes, debris from other material around the pulsar will be pulled into orbit around it. The debris will become superheated in the intense energy of the neutron star. The material becomes hot enough to radiate x-rays in addition to the radio signals being emitted by the pulsar itself.
In conclusion, quasars and pulsars are beautiful, powerful, and slightly terrifying, celestial formations. Quasars are black holes consuming super dense star dust and emitting faint radio signals. Pulsars are the remnants of once great stars that have lost all of their neutrons. They spin at an extremely fast rate and release high intensity beams that “pulse” in and out of view. They are both fantastic and interesting phenomenons of the universe.
Starting with black holes, Khalili describes the creation of one. I found that a black hole is what remains when a massive star dies. Because stars are so massive and made out of gas, there is an intense gravitational field that is always trying to collapse the star. As the star dies, the nuclear fusion reactions stop because the fuel for these reactions gets burned up. At the same time, the star's gravity pulls material inward and compresses the core. As the core compresses, it heats up and eventually creates a supernova explosion in which the material and radiation blasts out into space. What remains is the highly compressed and extremely massive core. The core's gravity is so strong that even light cannot escape. This object is now a black hole and literally cannot be seen because of the absence of light. Because the core's gravity is so strong, the core sinks through the fabric of space-time, creating a hole in space-time. The core becomes the central part of the black hole called the singularity. The opening of the hole is called the event horizon. Khalili describes that there are two different kinds of black holes:
The responsibility of super massive black holes is to hold the galaxies together. (Millis 2014) Super massive black holes are very dense and its believed that their density can reach infinity in a way that even light can't pass through their gravitational force. (NRAO 2014)
...f gas, which collapsed and broke up into individual stars. The stars are packed together most tightly in the center, or nucleus. Scientists believe it is possible that at the very center there was too much matter to form an ordinary star, or that the stars which did form were so close to each other that they coalesced to form a black hole. It is argued that really massive black holes, equivalent to a hundred million stars like the Sun, could exist at the center of some galaxies
Black holes - the strange scientific phenomenon that has astounded physicists and astronomers alike for decades. Popular subjects in science fiction novels, black holes are one of the greatest enigmas of the scientific world. Even today, the concept of a super-dense ball of matter that not even light can escape from is somewhat farfetched, and many scientists disagree with each other about nearly every aspect of a black hole. This project will attempt to shed some light on these mysterious formations, and will inform you the reader of the most popular and widely accepted theories surrounding them.
They’re carbon stars, a unique type of variable star, which accumulate soot in their upper atmosphere that scatters light near the blue end of the spectrum. What’s left for us to view is the red component of a star’s light. As the carbon particles build up, the star fades in brightness and gets even redder. Eventually, the carbon absorbs enough radiation to escape the star, and the cycle starts over again.
The American scientist John Wheeler coined the phrase “black hole” in 1969 to describe a massively compact star with such a strong gravitational field that light cannot escape. When a star’s central reserve of hydrogen is depleted, the star begins to die. Gravity causes the center to contract to higher and higher temperatures, while the outer regions swell up, and the star becomes a red giant. The star then evolves into a white dwarf, where most of its matter is compressed into a sphere roughly the size of Earth. Some stars continue to evolve, and their centers contract to even higher densities and temperatures until their nuclear reserves are exhausted and only their gravitational energy remain. The core then rushes inward while the mantle explodes outward, creating neutron stars in the form of rapidly rotating pulsars. Imploding stars overwhelmed by gravity form black holes, where the core hits infinite density and becomes a singularity (some estimate it at 10^94 times the density of water).
Just recently a major discovery was found with the help of a device known as The Hubble Telescope. This telescope has just recently found what many astronomers believe to be a black hole, After being focuses on a star orbiting empty space. Several pictures of various radiation fluctuations and other diverse types of readings that could be read from that area which the black hole is suspected to be in.
Comets and asteroids. They are some of the first celestial bodies that humans observed and truly thought about. From ancient cultures interpreting these near-Earth objects as signs of disaster, to 18th century Europeans studying their paths, to even the extinction of the dinosaurs, comets and asteroids have always been prevalent in the majority of Earth’s history. These objects have intrigued the human race for generations, and continue to do so today. These similar subjects of fascination have many unique and interesting characteristics and a rich history with Earth.
Black holes were originally thought to have only mere mathematical concepts. There was seemingly no possible way to compress any object into a space small enough to equal to its schwarzschild radius. Later however, astronomer Subrahmanyan Chandrasekhar calculated that stars much larger than our own sun should theoretically be able to collapse into a black hole (UTFC). A star is like a blown up balloon with the force of gravity trying to compress the balloon inwards and the air trying to push the balloon outwards. Likewise, stars are held in balance by gravity trying to collapse the star inwards going against the outwards pressure of the internal reactions of the star called nuclear fusion. If the star is big enough and the pressure inside quickly disappears, gravity would and should slingshot the star into a tiny point with near infinite density with an extremely strong gravitatio...
Tyler, Pat. Supernova. NASA’s Heasarc: Education and Public Information. 26 Jan. 2003. 22 Nov. 2004
By 1936, astronomers had realized that the hazy balls they sometimes saw in their telescopes, which looked like stars obscured by gas, were actually galaxies (Hibbison).
After a supernova, the core is likely to travel someplace else within space. When the core is less size than about 5 solar masses, the neutrons will halt the collapse of the star. This will create a Neutron Star. Neutron stars are observed as pulsars or X-ray binaries. When the core is very large, nothing that h...
Black holes are the result of the death of a massive star, leaving behind a dense remnant core that eventually collapses to create a gravitational force so strong that nothing, including light, can escape the force. The theory that black holes existed started back in the early 1900s and since then astronomers and scientists have been trying to get a better understanding of them. This phenomenon has been a working progress for astronomers and scientists for many years and as we develop a better understanding of our solar system, the more likely it is to make a significant discovery that can answer some of the most difficult questions about our incredible galaxy and solar system. The more information we are able to acquire about our universe, the more questions we might be able to answer about our existence. With advancements in technology we may be able to see some significant discoveries and insights into the world of black holes.
A galaxy, also called a nebula, consists of billions of stars, interstellar gas, dust, and dark matter which are all bound to form a massive cloud in which we live in. Although it cannot be very well explained, dark matter makes up at least 90% of a galaxy’s mass. Galaxies also contain billions upon billions of stars and their diameter can range from 1,500 to 300,000 light years. That’s huge! The Milky Way, the galaxy in which we live in, is one of about 170 billion galaxies in the observable universe. Our Sun is one of the billions of stars in our galaxy, and our eight planets revolve around this star in only a tiny part of our galaxy. “The Earth’s solar system is believed to exist very close to the Galaxy’s galactic plane, due to the fact that the Milky Way essentially divides the night sky into two virtually equal hemispheres” ("All About the Milky"). It definitely makes people second guess the fact of there being life on other planets.
Astronomers believe that most galaxies consist of a supermassive black hole at the center, which attracts all constituents of galaxies such as, dust, gases (mainly Hydrogen and Helium), atoms, stars, interstellar clouds and planets to the center by force of gravity, but are not sure whether all galaxies contain a black hole in the center. Galaxies keep moving in relative motion to one another and intermittently can come so close that the force of gravitational attraction between the galaxies may become strong enough to cause a change in the shape of the galaxies, while in exceptional cases, the galaxies may collide. If two galaxies collide, they may pass right through without any effect or may merge, forming strands of stars, extending beyond 100,000 light years in space (World Book Online Reference Centre, 2005). Hence, neighboring and often other colliding galaxies induce the sha...