White giants

RR Lyrae variables Less than a day Pulsating blue-white giants 4,500 known in Milky Way these stars are used to measure distances out to 200,000 pc (600,000 ly)... 

The evolution of a. star after it leaves the red-giant phase depends to some extent on its mass. If it is not more than about 1.4 M it may contract appreciably again and then enter an oscillatory phase of its life before becoming a white dwarf (p. 7). When core contraction following helium and carbon depletion raises the temperature above I0 K the y-ray.s in the stellar assembly become sufficiently energetic to promote the (endothermic) reaction Ne(y,a) 0. The a-paiticle released can penetrate the coulomb barrier of other neon nuclei to form " Mg in a strongly exothermic reaction ... 

Sillitoe, R.H. (1993) Giant and bonanza gold deposits in the epithermal environment Assessment of potential genetic factors. In Whiting, Mason, B.H. and Hodgson, C.H. (eds.). Giant Ore Deposits. Soc. Econ. Geol. Special Pub., 2, 125-156. 

The four general types of stars (main sequence, white dwarfs, giants and supergiants) provide a classification based on the fundamental observable properties but also suggest an evolution of stars. Astrochemically, the cooler giants and supergiants have many more atomic and molecular species that are the products of the nuclear fusion processes responsible for powering the stars. The nuclear fusion processes allow for the formation of more of the elements in the Periodic Table, especially the heavier elements that dominate life on Earth - principally carbon. 

Low (<1 solar mass) Middle (5-10 solar masses) High (>20 solar masses) Protostar — pre-main sequence — main sequence — red giant — planetary nebula — white dwarf — black dwarf Protostar - main sequence — red giant — planetary nebula or supernova —> white dwarf or neutron star Protostar — main sequence —> supergiant — supernova — neutron star... 

The plot of luminosity versus temperature for all stars, resulting in the main sequence, red giants and white dwarfs. Stellar evolution leads to mass - dependent birth lines onto the main sequence... 

The birth of a protostar and its life as a pre-main-sequence star, its descent to the main sequence and death, starting with a red giant leading to planetary nebula and ending in white and black dwarfs. This sequence varies with mass... 

Herzprung-Russell diagram A graphical plot of stellar intensity versus photosphere temperature showing that observed stars fall into classes main sequence, red giants, supergiants and white dwarfs. 

White, A.M., Swaisgood, R.R. and Zhang, H. (2003) Chemical communication in the giant panda (.Ailuropoda melanoleuca) the role of age in the signaller and assessor. J. Zool. Lond. 259, 171-178. 

Mappes, T., Koskela, E. and Ylonen, H. (1998) Breeding suppression in the bank vole under predation risk of small mustelids laboratory or methodological artifact Oikos 82, 365-369. Moore, L. A. (1995) Giant white-tailed rat. Uromys caudimaculatus. In R. Strahan (Eds.), The Mammals of Australia. Reed Books, Sydney, pp. 638-640. 

We are thus able to reconstruct the Sun s whole career, from its nebulous birth, through its first nuclear reaction, right up to its last breath as a red giant. We may watch it swell up proudly as it burns its first helium, then throw its envelope off a hot, dense core, before the latter grows rigid, becoming a white dwarf, frozen in crystal. Wonders But let us recall the vast effort that went into this undertaking. 

As the Sun turns red, humankind will die or fly, but let us not dwell upon this. Let us move on to the very end of our star itself. Eor in the end the Sun will mutate from a seething red giant to a sleeping white dwarf. 

Let us review all this. At an age of 12 billion years, the yellow dwarf will mutate into a red giant with 100 times the radius. This in turn will give way to a vaporous cloud with a very small white object at its centre. When the yellow dwarf has handed over to the white dwarf, the solar pageant will be close to an end. But for the moment, the Sun still shines staunchly. 

Among the various foul scenarios that lead to death by overdose, two stand out, with the common feature that they involve the same victim the white dwarf. In the hrst, the companion is an authentic star like the Sun or a red giant. In the second, much less probable, it is another white dwarf. 

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