In astronomy, stellar evolution refers to the changes which stars undergo during their lifetime. Stars change in color, luminosity, size and temperature through their lifespan. Scientist can not study an individual stars lifetime though because they far exceed ours and therefore we must study stellar evolution by observing the life cycle of numerous stars, each at a different point in its life cycle, and then running computer models which simulate the structure of stars. Through history stars have been recorded, starting with the brightest, which have been named going back as far as 1000 b.c. by the chinese. Today we name stars in three categories, the first being the brightest are named for what constellation they are in. Variable stars are the ones that change in luminosity periodically and the fainter stars are logged in the Henry Draper Catalogue under numubers like HD 12938. Stars exist either alone or in groups of two or more in a system or cluster. Large clusters are grouped into galaxies and in our Galaxy, the Milky Way there are more than 100 billion stars. There are also 10's of millions of galaxies that are part of the known universe. Think about that and tell me there's no life out there. As technology permitted it was found that stars positions are not fixed and that stars move at various speeds measured in changes of direction in fractions of a second of arc per year. This second of arc is the angular size of a pinhead that is 183 m away (wow, now thats precise, you would think). Many of the fainter stars almost seem to not move at all though because they are so far away and thats why we use them as reference stars to measure others and scientists call this proper motion. A Parallex is another apparent m... ... middle of paper ... ...rs of a fraction of a second. Its neutrinos send a shockwave out blasting most of the stars materials into space, but many of the elements get caught up in neutrinos and combine to create heavier elements. Without supernovae there would be no heavier elements than Iron-56. It is not understood well, but in some supernovae the gravity is so intense within the red supergiant that the electrons are forced into the atomic nuclei where they combine with protons to form neutrons. The electromagnetic forces keeping apart the seperate nuclei are gone and the entire core becomes a dense ball of neutrons or an atomic nucleus about the size of Manhatten called a Neutron Star. If the mass is great enough though, when the star turns into a red supergiant it will collapse under its on gravity into a radius smaller than the Schwarzchild Radius and turn into a Black Hole.
When itBetelgeuse cannot fuse anymore anything over iron, the star will not have enough energy to make heat. Eventually, the core will collapse. When Betelgeuse collapses, it is so strong and powerful that it causes the outer layers to rebound. With the rebound it will have an explosion, which is called a Supernova (Type two). The explosion has so much energy and power that the temperature becomes really hot. The temperature is so hot that it can use the fusion process much heavier than iron. The elements that were given off from the explosion are sent throughout space and are now new nebula. When the Supernova is done, it has left behind a star called a Neutron star. They form when atoms of the core of a dead star are crushed together and the end result produces neutrons. The neutrons are with electrons that are degenerate on the surface. Many Neutron stars have magnetic fields and they give off strong waves of radiation from their poles. These types of Neutron Stars are known as Pulsars.
With the passage of time, the universe rapidly expanded, cooled and thus became less dense than it was at the beginning of the universe. That allowed the formation of the very first atoms, hydrogen and helium. The slight nonuniformity in the density of the universe led to gravity attracting matter and then leading to the formation of dense lumps of matter which grew rapidly as time progressed by attracting even more matter inwards. This process continued until the hydrogen in the huge lumps started to fuse together and release enormous energy which blew all the matter in the nearby surrounding space of what could then be called one of the first “stars”. All the stars in the universe started as a huge lump of hydrogen formed by gravity in a nebula - an area of high abundance of interstellar matter and dust. Through nuclear fusion of hydrogen, heavier elements like helium, lithium, beryllium, etc. until iron, formed in the core of the stars. All the other elements are believed to have originated in violent explosions called
The two astronomers found many patterns after developing their graph. They found that 90% of stars graphed fell within a band that ran through the middle of the graph. These stars range from cool, dim, red stars at the lower right of the H-R Diagram to hot, bright, blue stars at the upper left corner of the H-R Diagram. The stars that fall into to this band are known as main-sequence stars. Stars such as the sun, and almost every start visible in the night sky fall within this band of main sequence stars. There is another group of stars which are cool and bright that appear near the upper right corner of the H-R Diagram.
The Big Bang, the alpha of existence for the building blocks of stars, happened approximately fourteen billion years ago. The elements produced by the big bang consisted of hydrogen and helium with trace amounts of lithium. Hydrogen and helium are the essential structure which build stars. Within these early stars, heavier elements were slowly formed through a process known as nucleosynthesis. Nucleosythesis is the process of creating new atomic nuclei from pre-existing nucleons. As the stars expel their contents, be it going supernova, solar winds, or solar explosions, these heavier elements along with other “star stuff” are ejected into the interstellar medium where they will later be recycled into another star. This physical process of galactic recycling is how or solar system's mass came to contain 2% of these heavier elements.
The dense core of the star continues to remain bound together by the force of gravity and pressures
Supernovas are explosions from old stars at the end of their life cycles. Their explosions are the largest and most energetic things in the Universe and can outshine their entire home galaxies. Supernovas can also provide beautiful viewing as well. Anyone in 1572, for a few weeks, could look up at the sky and see a bright “New star” in the sky.
During this lab we utilized the HR Diagram Explorer to complete the experiments in our lab. We adjusted the different temperatures (x-axis) and luminosity (y-axis) and were able to see the stars plot on the diagram. This diagram shows the different categories of stars; Supergiants, Main Sequence, Dwarfs and the many others. The stars that where mostly plotted in the middle are the Main Sequence stars. These star make
Stars explode at the end of their lifetime, sometimes when they explode the stars leave a remnant of gasses and, dust behind. What the gasses come together to form depend on the size of the remnant. If the remnant is less than 1.4 solar masses it will become a white dwarf, a hot dead star that is not bright enough to shine. If the remnant is roughly 1.4 solar masses, it will collapse. “The protons and electrons will be squashed together, and their elementary particles will recombine to form neutrons”. What results from this reaction is called a neut...
Walking on a clear night a person can’t help but look up and see the stars. Each beautiful, illuminating the night sky along with the moon, far away yet close enough to admire and wonder. I sit sometimes outside and just look up and gaze in wonder at the stars, but the scientists in me thinks further. The stars are like our sun in the solar system, hydrogen balls, exploding, radiating energy and light in all directions yet we are so far that we see them as specks in the night sky. Then there are those night where Venus and Mercury can be seen among the stars, almost a spiritual experience. Science has taught us that gravity and other laws of nature control the movement of such celestial objects and control everyday happenings where most would not give it a second thought.
Tyler, Pat. Supernova. NASA’s Heasarc: Education and Public Information. 26 Jan. 2003. 22 Nov. 2004
A star begins as nothing more than a very light distribution of interstellar gases and dust particles over a distance of a few dozen lightyears. Although there is extremely low pressure existing between stars, this distribution of gas exists instead of a true vacuum. If the density of gas becomes larger than .1 particles per cubic centimeter, the interstellar gas grows unstable. Any small deviation in density, and because it is impossible to have a perfectly even distribution in these clouds this is something that will naturally occur, and the area begins to contract. This happens because between about .1 and 1 particles per cubic centimeter, pressure gains an inverse relationship with density. This causes internal pressure to decrease with increasing density, which because of the higher external pressure, causes the density to continue to increase. This causes the gas in the interstellar medium to spontaneously collect into denser clouds. The denser clouds will contain molecular hydrogen (H2) and interstellar dust particles including carbon compounds, silicates, and small impure ice crystals. Also, within these clouds, there are 2 types of zones. There are H I zones, which contain neutral hydrogen and often have a temperature around 100 Kelvin (K), and there are H II zones, which contain ionized hydrogen and have a temperature around 10,000 K. The ionized hydrogen absorbs ultraviolet light from it’s environment and retransmits it as visible and infrared light. These clouds, visible to the human eye, have been named nebulae. The density in these nebulae is usually about 10 atoms per cubic centimeter. In brighter nebulae, there exists densities of up to several thousand atoms per cubic centimete...
...ions happen. Supernovas give off many elements we have today including hydrogen and heavier elements such as iron. Supernovas also play a big role in creating new stars because the aftermath of the explosion creates an elemental environment for new interstellar reactions to occur. Discovery of a supernova was difficult at first, given the fact that most occur far away from our galaxy, but new technology now allow scientist to discover many supernova within may galaxies.
Even though we know a great amount more than the astronomers in the past, there is still an even larger amount we do not know about the universe to this day. Even our own solar system contains many questions yet to be answered. Some of these include the possibility of a planet beyond Pluto (Planet X), the means by which the system was created, and even the possibility of a sister star to the Sun named Nemesis. Another astronomical mystery is the creation of the universe. In time, many questions will be answered but some will always remain. Astronomy is something that will never be completely understood.
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...
The idea behind the Solar Nebular Hypothesis is that the solar system was condensed from an enormous cloud of hydrogen, helium, and a few other elements and rocks. Around five billion years this cloud of materials began to spin and contract together into a disk shape under their own gravitational forces. The particles started combined together, protoplanets, to eventually form planets. A great mass of the material eventually began to form together, protosun, and make up the sun.