Pulsating White Dwarfs
Pulsating white dwarf stars are a special subclass of white dwarfs, and they are very useful tools for studying the interiors of stars. As the interior of the white dwarf changes and oscillates, the light signal from the star will pulsate at numerous frequencies. By determining the frequencies at which the star pulsates and using these as boundary conditions in stellar models, astronomers can determine the interior properties of white dwarfs. This summer I was involved in using data from the Whole Earth Telescope and CCD images to determine the frequencies at which two different white dwarf stars pulsate.
Background on Pulsating White Dwarfs
A white dwarf star is the final resting stage of 98 % of all stars (Kawaler A 1). The size of a white dwarf is comparable to Earth, but its mass is on the same order as the Sun. To keep such a dense star from collapsing, the core of the star, which is composed of carbon and oxygen, becomes electron degenerate. Surrounding the core is a thin layer of helium and hydrogen. This outer layer contains about .01% of the white dwarf’s mass, and it extends about 30 miles below the surface (Kawaler B 133). Without the thin “blanket” of hydrogen and helium, the white dwarf would cool very rapidly.
As the white dwarf cools, the release of heat is comparable to a pot of boiling water with a lid on it. As steam tries to escape, it causes the lid on the pot to move up and down. Instead of the outer layer of the star moving up and down, the outer layer will vary in luminosity due to nonradial pulsations/oscillations in the interior of the star. The changes in luminosity are on the order of millimagnitudes (11 millimagnitudes equals a 1% change in brightness), but the osc...
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... this summer were to perform data reduction on light curves of pulsating white dwarfs and to gain research experience. Over the course of the summer, I was successful in reducing the data of a pulsating white dwarf taken with WET because I
had found the independent frequencies at which the star pulsates. Besides being successful in find the independent frequencies, I also gained experience doing data reduction of light curves taken by WET and also CCD images. In the future, my experience may even allow me to take part of the next WET run.
Works Cited
Kawaler, Steven D. and Winget, Donald E. “White Dwarfs: Fossil Stars.” Sky and Telescope. August 1987.
Kawaler, Steven D. and Dahlstrom, Michael. “White Dwarf Stars.” American Scientist. In press 2000.
Nather, Edward R. and Winget, Donald E. “Taking the Pulse of White Dwarfs.” Sky and Telescope. April 1992.
The use of euphemism and crudeness in “The Wife of Bath’s Prologue” is simultaneously unnerving and amusing, and begs the question of how a “wicked” woman like The Wife could ever actually progress in medieval society. Chaucer incorporates subtle allusions to female sexual organs and it is this bluntness (that would raise eyebrows even today) which establishes the Wife as such a powerfully outspoken character. Because courtship in Chaucer’s time was considered worthy of complete submission, the fact that the Wife places such emphasis on domination and even psychological power hints at her being an object of irony (and not a feminist figure “before her time”). It is for this reason that Chaucer’s delicate use of “queynte”- a term from which
As the White dwarf travels around the other star, if it has a strong enough gravity, it will begin pulling matter from the outer layers of the star into something called an accretion disk, not really coming into contact with the dwarf itself. This event alone does not actually cause the supernova, but over time, a series of smaller novas will occur from the White dwarf. A nova happens after the dwarf has collected some matter from the other star, and the star will shed some of that matter into space through a smaller explosion, which will cause a brightening of the star that can be detected through a telescope, but not to the human eye unless it happened much closer to Earth. But, because not all of the matter will be ejected into space, some will remain, and eventually, after hundreds or thousands of novas, the matter in the accretion disk will have built up so much that it has increased the gravity of the White dwarf. However, because white dwarves are meant to be small with a relative low gravitational field, this becomes a problem. Once enough matter forms in the accretion disk, the white dwarf will pass the Chandrasekhar Mass limit, which is basically the limit of how large a white dwarf can be, before its gravity will fold in on itself, which is exactly what happens after the series of novas. Once it passes the Chandrasekhar limit, because the
...leted of its nuclear fuel and lost its outer layers. When a small to medium (less than 10 solar masses) main-sequence star begins to run out of fuel in its core, the core will begin to collapse where hydrogen on the edges of the collapsed core can be compressed and heated (Chandra 2012). The nuclear fusion of this new hydrogen will create a new gush of power that will make the outer layers of the star to expand out; this is known as the red giant phase. In the red giant phase over millions of years, all of the stars energy supplies are used up leaving behind a hot core that is still surrounded by the expanded outer layers. The outer layers are eventually expelled by stellar winds which end up creating a planetary nebula and the hot core left behind forms a white dwarf star where the pull of gravity is supported by degeneracy pressure (p. 538 Bennett en al. 2013).
“The Wife of Bath’s Tale” is written in an entertaining and adventurous spirit, but serves a higher purpose by illustrating the century’s view of courtly love. Hundreds, if not thousands, of other pieces of literature written in the same century prevail to commemorate the coupling of breathtaking princesses with lionhearted knights after going through unimaginable adventures, but only a slight few examine the viability of such courtly love and the related dilemmas that always succeed. “The Wife of Bath’s Tale” shows that women desire most their husband’s love, Overall, “The Wife of Bath’s Tale” shows that the meaning of true love does not stay consistent, whether between singular or separate communities and remains timeless as the depictions of love from this 14th century tale still hold true today.
“The Wife of Bath’s Tale” in The Canterbury Tales by Geoffrey Chaucer is a story about a widow who took a pilgrimage to the town of Canterbury with an array of dynamic characters whose diverse backgrounds allowed them to share their stories with one another to make the long journey more interesting. The widow named Alisoun in the “The Wife of Bath’s Tale” told the tale of her experiences with her five past husbands and a story about a knight and a witch. She truly believed that for a woman to have a happy life she would need to gain dominion over a man; however one could assume this was programmed into her by her influential mother and her own religious doctrines. Accordingly, Alisoun argued that the woman must control everything in order to have a happy marriage; however, her life experience and the story she shared should tell her otherwise.
Tyler, Pat. Supernova. NASA’s Heasarc: Education and Public Information. 26 Jan. 2003. 22 Nov. 2004
Huppé, Bernard F. "Rape and Woman's Sovereignty in the Wife of Bath's Tale." Modern Language Notes 63.6 (1948): 378-81. The Johns Hopkins University Press.
Carter, Susan. "Coupling the Beastly Bride and the Hunter Hunted: What Lies Behind The Wife of Bath's Tale." Chaucer Review, Vol. 37 No. 4 (2003), 329-345.
Ungar, Peter S. Evolution of the Human Diet: The Known, the Unknown, and the Unknowable. Oxford: Oxford UP, 2007. Print.
However, a divorced woman is automatically viewed as less desirable for suitors if she chooses to marry again. The unfairness of this advantage in the marriage market is presented throughout the poem. Women are viewed as objects that are meant to only serve their husbands commands. The Wife of Bath takes charge in reverses the stereotypical roles by taking charge in her first two marriages and her overall views on sex. Her carefree attitude strikes down the connation’s that women should only be limited to having sex for procreation and for her own personal pleasure. She explains how God wanted Adam and Eve to multiply and that is only possible by having sex. The Wife of Bath elaborates, “But wel I woot expres, withoute lye, God bad us for to wexe and multiplye: That gentil text can I wel understonde. “ (27-29). She uses the bible as a template to justify her actions of having sex for pleasure and procreation. As the church uses the bible to socially repress women from their sexuality. In addition, the wife of bath describes the difference in viewpoints for husbands and wives on their positions in a marriage. A woman in this time period looks at marriage as a profession where she obliges to her husband’s every command. A man looks at marriage more for pleasure and enjoyment. The wife explains the power
Casagrande, L., et al. "Strömgren Survey for Asteroseismology and Galactic Archaeology: Let the SAGA Begin." Astrophysical Journal 787.2 (2014): 110.
Women have the ability to get what they want, when they want it. Chaucer portrays the Wife of bath as the dominant person in her marriages. She looks at men as her trinkets to be used and played with. She moves from one man to another, always looking for more. The Wife of Bath is a control freak, wanting to have sex when she desires it and with whom she desires.
Everything in the world dies, even stars. A supernova occurs when a star “dies.” A supernova is the explosion of a star. These explosions release huge amounts of energy, an amount equivalent to a few octillion nuclear warheads, or one million tons of TNT. One supernova will radiate more energy that our son will its entire lifetime. Supernovae play a huge part in the galaxy by being a primary source of heavy elements in the universe Throughout a large stars life, they create heavy elements within their core. When one of these stars star explodes, it releases the heavy elements into the galaxy. The elements then disperse and move on to create new stars and the cycle continues anew.
The Wife of Bath 's prologue and tale has a very personal authenticity to it. Although Geoffrey Chaucer is the author, the wife of Bath takes agency to talk about herself and her experiences. It is almost as if the wife speaks for him. The expectations of married women, at the time The Canterberry Tales were written, were to be modest, true and obedient wives. The wife of Bath, however, admits to using her own experiences as the source of her knowledge in marriage, and not the views of society. It is the fact that she relies on her internal thoughts and experiences that allows one to see her (and Chaucer 's) personal insight on the desires of married women. Although some may say that the wife of bath is simply looking for dominion over her husbands, Chaucer characterizes the wife of bath as a bold woman, and also uses the first person point of
At the dawn of the information age, to be young, as Wordsworth said in another context, is very heaven. Getting to know what goes inside computers, the engines of the Information Technology revolution, and knowing how to work with them enables one to understand the technology that makes it all possible. Understanding this, I chose to do my undergraduate study in Electronics and Communications engineering.