Stars Constellations

Gestim, n. star constellation, gestimt, a. starred, starry browed, gestoben, p.p. (of stieben) scattered. 

Star Constellation Type of star Distance (light- years) Mass Radius Surface Intrinsic Magni-(solar (solar temperature brightness tude masses) radius) (Fahrenheit) (relative to sun) ... 

Ironically, the word Arctic comes from the ancient Greeks, who understood that the northernmost part of the earth lay under the stars of the constellation Ursa Major, the Great Bear. Although unaware of the polar bear, they called this region Arktikos, which means the country of the great bear. ... 

Now that we have a simple model for the continuum spectrum of the stars based around the Planck curve, the temperature and the luminosity, we can make some observations and classifications of the stars. There are some constellations that dominate the night sky in both the northern and southern hemispheres and even a casual look should inspire wonder. Star hopping in the night sky should lead to the simplest observation not all stars have the same colour. A high-quality photograph of the constellation of Orion (see page 2 of the colour plate section) shows stars... 

The emission of light from Cepheid stars has a characteristic light curve seen in Figure 4.14 for a Cepheid in the constellation of Perseus. The sawtooth pattern is characteristic of the class and enables the period of variation to be determined. The observation, however, that the luminosity and period are related has powerful consequences. The Cepheid variables fall into two classes type I classical Cepheids have periods of 5-10 days and type II have periods of 12-20 days. The two types of Cepheids initially caused problems when determining the luminosity-period relation but the relation has now been determined. Type I Cepheids follow the expression... 

Current extrasolar planets are all much larger than the Earth. The total count at present (9 September 2005) is 168 found in 144 planetary systems, of which 18 contain multiple planets. The first to be discovered was 51-Pegasi in the constellation of Pegasus by the radial velocity method. It is about 0.45 Mjupiter and has an orbital period around the star of about 4.5 days. Of the 168 planets found so far only nine are present within a habitable zone around their star. The survey of the star catalogue for planets has only just started and we have found a large number of planets very quickly - solar systems, at least, are not special. 

Constellation A collection of stars that when viewed from Earth appear to form a shape in the night sky. 

Another limitation to the use of PCA comes from the fact that being a linear projection it may introduce mistakes. Indeed, in the projection, data separated in the original space may result in a similar score, a phenomenon like that producing a constellation in the starred sky. 

Promethium is a silvery-white, radioactive metal that is recovered as a by-product of uranium fission. Promethium-147 is the only isotope generally available for smdy. The spectral lines of promethium can be observed in the light from a distant star in the constellation Andromeda. Even so, it is not found naturally on Earth, and scientists consider it to be an artificial element. Its melting point is 1,042°C, its boiling point is estimated at 3,000°C, and its density is 7.3 g/cm. ... 

Fig. 6.1. Stellar nursery in the constellation of Orion. Molecular clouds A and B were detected by their radio emissions. They appear to have given birth to several generations of stars (la, It and Ic).

Throughout the final phases, the solar wind will sweep across the Earth, tearing up the surface. The atoms of our dead will be driven from below and returned to the Sun. The Earth will surrender her dead. Finally, lit up by the bright white glare of the central star, the ejected matter will blossom into a beautiful planetary nebula rather like the one that so delightfully ornaments the constellation of the Lyre. The atoms of all human beings will shine in the sky, mixed with those of the animals and the stones. 

An object which is about 300 light years in diameter and which closely resembles the terminal stage of a supernova explosion is visible today in the constellation Orion (the Orion Halo). A number of very bright young stars are located within the Orion Halo, and their ages are estimated to be less than 5-10 million years obviously their formation was triggered by the shock wave of the supernova explosion. 

Celsius was a professor of astronomy al Uppsala University. He is noted for trying to determine the magnitude of the stars in (he constellation Aries. He published 316 of his observations on the aurora borealis. 

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