My Date with the STARS

My Date with the Stars

JOHN KENNETH KIM I. ARCANGrade 6 ErosScience

BackgroundWhen you look up at the night sky, you can see many beautiful stars. If you are out in the open field, farm or provinces, you may see thousands of them twinkling in the dark skies over mountains and away from the city lights. There may even be times when you may see part of the Milky Way (ooohhh, yum!) Oops, not the chocolate bar, mate! In a town or city, you may not really see as many stars because the city lights swallow their glitter.

We may not know it but there are several classifications of stars and they even vary in intensity and temperature. Some stars may be hot or cool. Some are brighter than the others. Some are big, some are small. In fact, a couple of stars were discovered to be larger than the sun by 100 to 200 times. There are stars which are smaller than the Earth. Scientists and students study stars and group them according to their likeness or differences.

Surprisingly, these stars have names. I wish there is one named John, Kenneth or Kim. Oh well, join me in my odyssey to space and learn about these diamonds in the sky.

Table of Contents

I. Background ---------------------------------------------------------1II. Why Stars Objectives of the Study -------------------------3III. Twinkle Twinkle A Starry Overview -------------------------4IV. All About Stars ------------------------------------------------------5V. Beyond the Galaxy A Conclusion ------------------------10VI. Sources References --------------------------------------------11

Why Stars

This research was conducted in order to answer the following questions:1. Do stars come from nowhere?2. Are there different types of stars?3. Do stars have similarities and differences?

Twinkle Twinkle A Starry OverviewStars are giant, luminous spheres of plasma. Galaxies consist of stars, stellar remnants, dust, gas, and dark matter, bound together by gravity. Learn more about stars and galaxies.Basically, stars are big exploding balls of gas, mostly hydrogen and helium. Our nearest star, the Sun, is so hot that the huge amount of hydrogen is undergoing a constant star-wide nuclear reaction, like in a hydrogen bomb. Even though it is constantly exploding in a nuclear reaction, the Sun and other stars are so large and have so much matter in them that it will take billions of years for the explosion to use all the "fuel" in the star. The huge reactions taking place in stars are constantly releasing energy (called electromagnetic radiation) into the universe, which is why we can see them and find them on radio telescopes such as the ones in the Deep Space Network (DSN). Stars, including the Sun, also send out a solar wind and burst out occasional solar flares.

All About Stars

A star is a great ball of gas formed mostly from element hydrogen which is converted to helium through a thermonuclear reaction called fusion.

Stars, though often immediately seen in the sky, follow a specific life cycle. This cycle is:

1. Nebula2. New Star (large)3. Red Supergiant4. Supernova5. Black Hole6. Neutron Star

Stars following this complete life cycle also show the peculiarities of these twinkies. They give each specific star an identity of its own.

Classification of Stars

There are different classifications of stars, namely: Variable Stars, Binaries and Nova. They not only vary in names, they also have their own qualities.

Variable Star is, quite simply, a star that changes brightness. A star is considered variable if its apparent magnitude (brightness) is altered in any way from our perspective on Earth. These changes can occur over years or just fractions of a second, and can range from one-thousandth of a magnitude to 20 magnitudes. More than 100,000 variable stars are known and have been catalogued, and thousands more are suspected variables. Our own sun is a variable star; its energy output varies by approximately 0.1 percent, or one-thousandth of its magnitude, over an 11-year solar cycle.

The first modern identified variable star was Omicron Ceti, later renamed Mira. It had been described as a nova in 1596 by David Fabricius. In 1638, Johannes Holwards observed Omicron Ceti pulsating in a regular 11-month cycle. This was an important discovery, as it helped verify that the stars were not eternal and invariable as ancient philosophers such as Aristotle had believed. The discovery of variable stars, along with reports of supernovae, paved the way for development of the science of astronomy.

In the abstract of a talk given to celebrate the 400th anniversary of Miras discovery, Dorrit Hoffleit, of Yale University, said, Within the first century following Fabricius, four Mira-type variables were discovered, and in all cases it has been found that the stars were suspected of being novae long before their "official" discovery in the Western World. Three of the four had been recorded as novae in early Chinese or Korean records. (Retrieved from http://www.space.com/15396-variable-stars.html)Binaries are two stars orbiting a common center of mass. The brighter star is officially classified as the primary star, while the dimmer of the two is the secondary (classified as A and B respectively). In cases where the stars are of equal brightness, the designation given by the discoverer is respected.Binary pairs can be classified based on their orbit.Wide binariesare stars that have orbits which keep them spread apart from one another. These stars evolve separately, with very little impact from their companions. They may have once contained athird star, which booted the distant companion outward while eventually having been ejected themselves.

Binary star systems provide the best means for scientists to determine the mass of a star. As the pair pulls on one another, astronomers can calculate its size, and from there determine characteristics such as temperature and radius. These factors help characterize singlemain sequence starsin the universe. (Retrieved from http://www.space.com/22509-binary-stars.html)

Nova (plural novae or novas) is a cataclysmic nuclear explosion on a white dwarf, which causes a sudden brightening of thestar. Novae are not to be confused with other brightening phenomena such as supernovae or luminous red novae.

Novae are thought to occur on the surface of a white dwarf in abinary systemwhen they are sufficiently near to one another, allowing material (mostly hydrogen) to be pulled from the companion star's surface onto the white dwarf. The nova is the result of the rapid fusion of the accretedhydrogen on the surface of the star, commencing a runawayfusionreaction.

Similarities and Differences Characteristics of Stars

Stars, with their own characteristics make them really special. In fact, would you believe that the Sun, the center of the Solar System is considered an average star not too hot, not too cold; not too large, not too small.

They have four color changes which includes red, yellow, white and blue. These colors also give the stars their temperature. The Sun as 5,000 C is not the hottest among the stars. Their temperatures range from 2,000 C to 50,000 C. The coolest, at 2,000 C, is Red in color while the hottest, at 50,000C is Blue in color.

Hereunder is an example of Star colors and temperatures:

ColorTemperatureExamples

Blue white12,000Rigel, Spica

White11,000Vega

White10,500Sirius

Yellow6,000Cepalla

Yellow6,000Sun

Orange4,200Arcturus

Red3,000Antares

Red2,200Betegeuse

Stars also have differences in terms of sizes and brightness. These are the reasons why some are seen visibly while others are not. They make the stars seem to sparkle in the night sky. Brightness is related to the distance from the earth and the age of the star. Classifying stars by their brightness, they can either be 1st magnitude stars are the brightest or 6th magnitude stars are the weakest. These magnitude are also grouped as Apparent Magnitude which dictates the brightness as it appears to us and the Absolute Magnitude which tells us the stars brightness given a certain distance.

Beyond the Galaxy A Conclusion

In the end, each star in the sky is an enormous glowing ball of gas. Our sun is a medium-sized star.

Stars can live for billions of years. A star is born when an enormous cloud of hydrogen gas collapses until it is hot enough to burn nuclear fuel (producing tremendous amounts heat and radiation). As the nuclear fuel runs out (in about 5 billion years), the star expands and the core contracts, becoming a giant star which eventually explodes and turns into a dim, cool object (a black dwarf, neutron star, or black hole, depending on its initial mass). The largest stars have the shortest life span (still billions of years); more massive stars burn hotter and faster than their smaller counterparts (like theSun).

Indeed, Stars are amazing as they follow a life cycle. They are not just pop-ups in the sky at night. They have a living pattern which also affect all sorts of colors, temperatures, brightness and distances. They live among and within us.

Next time you sing Twinkle Twinkle Little Stars, remember that these glowing balls of gas are interesting diamonds in the sky.

Sources

http://www.space.com/15396-variable-stars.html http://www.space.com/22509-binary-stars.html www.dvd-ppt.slideshow.com www.kidsastronomy.com/stars.html www.cosmos4kids.com/files/stars_intro.html www.enchantedlearning.com/subjects/astronomy/stars http://www.google.com.ph/images http://curious.astro.cornell.edu

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