Understanding Variable StarsCambridge University Press, 24 mag 2007 - 350 pagine This book was first published in 2007. Variable stars are those that change brightness. Their variability may be due to geometric processes such as rotation, or eclipse by a companion star, or physical processes such as vibration, flares, or cataclysmic explosions. In each case, variable stars provide unique information about the properties of stars, and the processes that go on within them. This book provides a concise overview of variable stars, including a historical perspective, an introduction to stars in general, the techniques for discovering and studying variable stars, and a description of the main types of variable stars. It ends with short reflections about the connection between the study of variable stars, and research, education, amateur astronomy, and public interest in astronomy. This book is intended for anyone with some background knowledge of astronomy, but is especially suitable for undergraduate students and experienced amateur astronomers who can contribute to our understanding of these important stars. |
Sommario
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AAVSO absorption abundance accretion disc activity amateur amplitude appear astronomers atmosphere become binary brightness called cause Cepheids changes close clusters colour companion complex component cool cycle determined developed diagram discovered distance dust eclipsing effect elements emission energy especially evolution figure first galaxy giant gravitational important increases instability instance interesting known layers less light curve lines luminosity magnetic field magnitude mass massive material maximum measured method Mira models modes motion nature normal Note novae objects observed occur orbit outbursts period phase photometric physical Population possible produced properties pulsation radial radial velocity radius range recently regions relation relatively result rotation satellite scale seen sequence shows space spectra spectroscopic spectrum stellar stellar wind supernovae surface Tauri stars techniques telescopes temperature usually variable stars variations vary visible visual wavelengths white dwarf X-ray
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Pagina 6 - Therefore do I lay these hitherto sorely neglected variables most pressingly on the heart of all lovers of the starry heavens . May you become so grateful for the pleasure which has so often rewarded your looking upward, which has constantly been offered you anew, that you will contribute your little mite toward the more exact knowledge of these stars!
Pagina 5 - The whole subject of variable stars," says Herschel, " is a branch of practical astronomy which has been too little followed up, — it holds out a sure promise of rich discovery." It is also a branch in which amateur astronomers, with moderate instrumental means, or even with good eyes alone, can labor to advantage. (6.) But we have not yet reached the widest field of inquiry. With telescopes of good definition and great power...
Pagina 7 - ... the more exact knowledge of these stars! May you increase your enjoyment by combining the useful and the pleasant, while you perform an important part towards the increase of human knowledge, and help to investigate the eternal laws which announce in endless distance the almighty power and wisdom of the Creator! Let no one, who feels the desire and the strength to reach this goal, be deterred by the words of this paper. The observations may seem long and difficult on paper, but are in execution...
Pagina 17 - The declination of a star is its angular distance north or south of the celestial equator, measured along the hour circle through the star. Its right ascension is the angular distance along the celestial equator, from a fixed point called the vernal equinox to the foot of the hour circle through the star. Because of the relative motion of the star and the solar system, and the precession and nutation of the equinoxes, these quantities change slowly from year to year, and because of the motion of...
Pagina 17 - Star positions are complicated by precession: a 26 000-year conical motion of the earth's rotation axis, caused by the gravitational pull of the moon and sun on the earth's equatorial bulge.
Pagina 4 - BRAHE on A New Star, not Previously Seen within the Memory of Any Age Since the Beginning of the World.
Pagina 35 - These three frequencies are separated by the rotation frequency, and their amplitude ratios depend on i (the inclination of the rotation axis to the line of sight) and 0 (the angle between the magnetic and rotation axes).
Pagina 25 - The apparent change in the position of an object when viewed from two different locations; used to measure the distance to nearby stars.
Pagina 69 - The computational algorithm yields values for the parameters a, b, c and z which minimize the sum of the squares of the differences between the raw and smooth values of y. The squared differences are weighted by the number of cases associated with each set of data points.
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