Slacker Astronomy How the Sun Shines by John N. Bahcall* What makes the sun shine? How does the sun produce the vast amount of energy necessary to support life on earth? These questions challenged scientists for a hundred and fifty years, beginning in the middle of the nineteenth century. Theoretical physicists battled geologists and evolutionary biologists in a heated controversy over who had the correct answer. Why was there so much fuss about this scientific puzzle? The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. In this essay, we shall review from an historical perspective the development of our understanding of how the sun (the nearest star) shines, beginning in the following section with the nineteenth-century controversy over the age of the sun. The Age of the Sun How old is the sun? The older the sun is, the greater the total amount of radiated solar energy. Conflicting Estimates of the Solar Age Who Was Right? What was wrong with Kelvin's analysis? F.W.
Bienvenidos a GEDRAA (Grupo de Estrellas Dobles RAA)) Home Page A supermassive star, all alone A visible/infrared composite view of the Tarantula, with VFTS 682 at its centre. (Image: ESO/M.-R. The Tarantula Nebula is a gift that keeps on giving – if you’re into really massive stars, that is. Some of the region’s clusters contain the most massive stars we know today. The most massive stars form almost exclusively in clusters, as the clouds they form out of have to be so massive that many smaller stars are inevitably born in the process. Some scientists even propose that the combined winds from supermassive clusters like R136 could even be responsible for blasting heavy elements out of their galaxies entirely, into the intergalactic medium. The newly discovered behemoth star , named VFTS 682, is around a million times more luminous than the Sun, and around 150 times as massive. Our current modes of how massive stars form have no way of explaining the formation of a 150 solar star all on its own. References Joachim M. Norman Murray, Brice Ménard, & Todd A.
Últimas noticias Astronomy Picture of the Day 'Zombie' stars "Zombie" stars that explode like bombs as they die, only to revive by sucking matter out of other stars. According to an astrophysicist at UC Santa Barbara, this isn't the plot for the latest 3D blockbuster movie. Instead, it's something that happens every day in the universe - something that can be used to measure dark energy. This special category of stars, known as Type Ia supernovae, help to probe the mystery of dark energy, which scientists believe is related to the expansion of the universe. Andy Howell, adjunct professor of physics at UCSB and staff scientist at Las Cumbres Observatory Global Telescope (LCOGT), wrote a review article about this topic, published recently in Nature Communications. LCOGT, a privately funded global network of telescopes, works closely with UCSB. Supernovae are stars that have been observed since 1054 A.D., when an exploding star formed the crab nebula, a supernova remnant. "That's what our sun will be at the end of its life," he said.
PLoS Biology : Publishing science, accelerating research A Peer-Reviewed, Open Access Journal Current Issue PLOS Biology is a peer-reviewed, open-access journal featuring research articles of exceptional significance in all areas of biological science, from molecules to ecosystems. “Impossible” Star Exists in Cosmic Forbidden Zone Want to stay on top of all the space news? Follow @universetoday on Twitter This ancient star, in the constellation of Leo (The Lion), is called SDSS J102915+172927 and has been found to have the lowest amount of elements heavier than helium of all stars yet studied. It has a mass smaller than that of the Sun and is probably more than 13 billion years old. Astronomers say a newly found star should not exist and is in the “forbidden zone” of a widely accepted theory of star formation. “A widely accepted theory predicts that stars like this, with low mass and extremely low quantities of metals, shouldn’t exist because the clouds of material from which they formed could never have condensed,” said Elisabetta Caffau (Zentrum für Astronomie der Universität Heidelberg, Germany and Observatoire de Paris, France), lead author of the paper appearing in this week’s edition of Nature. The team found the star with the X-shooter and UVES instruments on the Very Large Telescope. Source: ESO