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Topic: Population III stars

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	Population III stars - Wikipedia, the free encyclopedia
		Population III stars are a hypothetical population of extremely massive stars that are believed to have been formed in the early universe.
		Analysis of data on low-metallicity Population II stars, which are thought to contain the metals produced by Population III stars, suggests that these metal-free stars had masses of 10 to 100 solar masses instead.
		This is why astronomers consider population III to be somewhat of a mystery, by all rights they should not exist yet they're needed to explain the quasar observations.
	en.wikipedia.org /wiki/Population_III_stars (490 words)

	Stellar population - Wikipedia, the free encyclopedia
		Population II stars are the first long-lived stars to have formed after the Big Bang, and therefore have low metal abundance.
		Population II stars are found in globular clusters and in the Galactic Halo of the Milky Way (as CS22892-052, CS31082-001, HE0107-5240, HE1327-2326).
		Population II stars are much older than Population I stars, contrary to what one might expect from the numbers assigned to them.
	en.wikipedia.org /wiki/Stellar_population (387 words)

	SCIENTISTS SPEAK ABOUT THE ORIGIN OF MATTER - 1 (Site not responding. Last check: 2007-10-09)
		stars are composed of material like the sun, not like the earth.
		Such primordial `Population-III' stars would contain vanishingly small abundances of heavy elements."—"Where is Population* III?" Sky and Telescope, 64:19 (1982) [Nucleosynthesis"=production of heavier elements by nuclear fusion].
		Persuading expanding gases to form themselves into galaxies of stars and planets requires an adjustment of gravitational and explosive forces quite as delicate as that between the two halves of a pencil in balance on a razor's edge.
	www.pathlights.com /ce_encyclopedia/01-ma6.htm (1860 words)

	HE 0107-5240
		The star is located in the southern part (1:7-52:40) of the Constellation Phoenix, the Phoenix or Firebird -- northwest of Zeta Phoenicis and Achernar (Alpha Eridani); southwest of Beta and Delta Phoenicis, southeast of Lamda1, Mu, Epsilon, Kappa, and Alpha Phoenicis (Ankaa); and north of Eta Phoenicis.
		As a result, the second generation of stars (Population II) were born with the first doses of heavier elements (such as carbon, oxygen, silicon, sulfur, neon, magnesium, and iron), although most have an heavy-element abundance that is only 1/10th to 1/1000th of Sol's metallicity.
		As these "halo stars" were born when the Milky Way was young, their motions through and outside of the spiral disk still carry the imprint of the process by which the galaxy formed, when gravity brought gas together to create the first stars.
	www.solstation.com /x-objects/he0107.htm (960 words)

	MPA/ESO Conference on the First Stars: Abstracts: (Site not responding. Last check: 2007-10-09)
		Abstract: I summarize the observational search for the elusive Population III stars, and indicate new efforts which are necessary to expand the sample of known Galactic stars with [Fe/H] < -3 in the near future.
		Ionizing fluxes of hot stars depend crucially on the strengths of their stellar winds, which which modify the absorption edges of hydrogen and helium (neutral and ionized) in the far UV.
		The abundance histories of r-process and s-process nuclei in field halo stars and globular clusters can thereby be used to constrain the timescale for halo nucleosynthesis activity and/or the IMF in the early stages of the Galaxy.
	www.mpa-garching.mpg.de /english/conferences/stars99/abstracts.html (2962 words)

	Galactic archaeology (Site not responding. Last check: 2007-10-09)
		Population II stars, on the other hand, formed before a well-ordered Galaxy was in place, so their orbits have both a wide range of eccentricities and no preferred direction of rotation, so that many are going around the Galaxy in the opposite direction to the Sun.
		The Population III stars may also have formed before the gas which formed the Galaxy had collapsed into its current location, and hence they will be located even further away from the Sun than the Population II stars in the halo of our Galaxy.
		It is possible that Population III stars rotated faster than ones with more metals, and that this gave an extra boost to the loss of their outermost layers.
	physics.open.ac.uk /~sgryan/an00.html (2668 words)

	How Heavy Can a Star Get (Site not responding. Last check: 2007-10-09)
		The most massive stars are the brightest, and they are known as “Supergiants” because of their large size and their enormous luminosity compared to most other stars (Moore, 2002).
		Stars with a mass greater than 100 Solar masses do not have their maximum luminosity in the optical bands, which makes photometry of these stars difficult.
		A massive star often has more than one companion which constrains their formation, and a significant fraction of all massive OB stars are found far from their probable birth site, presumably because they were ejected from cores of binary-rich star systems (Kroupa, 2004).
	www.grasslands.org /MassiveStars.htm (1712 words)

	First Stars / Population III
		Hence, the first stars (often called Population III stars) may have been very massive, hot, and bright, with 100 to 1,000 Solar-masses (more discussion on Jeans mass and metal-free stars and Bromm et al, 2002, in pdf).
		At least one simulation suggests that only one massive star star may have formed for each proto-galactic clump because of resistance to renewed fragmentation of the star-forming cloud and intense radiation once the star is formed (Abel et al, 2002).
		Well-illustrated articles on the formation of the first stars are available from the December 2001 issue of Scientific American by astronomers Richard Larson and Volker Bromm (in pdf) and the December 2002 issue of Discover by Tim Folger.
	www.solstation.com /x-objects/first.htm (2095 words)

	BBC - Final Frontier
		Population III stars could also have become supernovae so quickly that they polluted their more slowly forming neighbours which we now observe as Population II stars.
		Population III stars may also have formed before the Galaxy, so few would be found near the Sun.
		One possibility is that primitive stars were better able to throw off their outer layers than more modern stars are; perhaps they rotated faster and this gave an extra boost to the loss of their outermost, carbon-rich layers.
	www.open2.net /science/finalfrontier/research/jan_2002/research_page6.htm (280 words)

	Scientists See Light that May Be from First Objects in Universe (Site not responding. Last check: 2007-10-09)
		The Goddard team says that this glow is likely from Population III stars, a hypothesized class of stars thought to have formed before all others.
		Theorists say the first stars were likely over a hundred times more massive than Earth's sun and extremely hot, bright, and short-lived, each one burning for only a few million years.
		The ultraviolet light that Population III stars emitted would be redshifted, or stretched to lower energies, by the universe's expansion.
	www.sflorg.com /spacenews/sn110205_03.html (995 words)

	Population I star concept from the Astronomy knowledge base (Site not responding. Last check: 2007-10-09)
		The brightest of this Population are hot, white stars.
		has definition Young star with relatively high abundances of metals, and are usually found in the disk of a galaxy, especially the spiral arms, in dense regions of interstellar gas.
		Population I Cepheid (3 kinds, 34 facts) (classical Cepheid, young disk Cepheid) - A Cepheid which is about 4 times more luminous than Population II Cepheids, probably because of their higher metal content (although mass may also be a factor).
	www.site.uottawa.ca:4321 /astronomy/PopulationIstar.html (371 words)

	pr-19-02.html
		This star was observed in December 2001 with the UV-Visual Echelle Spectrograph (UVES) on the 8.2-m VLT KUEYEN telescope at the ESO Paranal Observatory (Chile).
		These "halo stars" were born when the Milky Way galaxy was young and their motions still carry the imprint of the process by which our galaxy formed, when gravity brought the gas together and the first stars appeared.
		The "halo stars" are said to belong to "Population II", in contrast to the younger stars in the disk (like the Sun) that are referred to as "Population I" stars.
	www.eso.org /outreach/press-rel/pr-2002/pr-19-02.html (1916 words)

	ESA Portal - ESA on the trail of the earliest stars
		Chemical elements such as oxygen, carbon, iron and so on were forged later, in the nuclear furnaces at the hearts of stars and then cast into space at the end of the star's life.
		The theory of population III stars suggests they are long dead in the local Universe.
		New research suggests that even if the population III stars are extremely far away, JWST would see them exploding as supernovae, at the ends of their individual lives.
	www.esa.int /esaCP/SEM99G1A6BD_index_2.html (765 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		It is not clear what these stars' properties were, when they formed or how long their era lasted before leading to the stars and galaxies we see today.
		Theoretical arguments suggest that Population III stars were very massive and short-lived stars that formed at redshifts z ~ 10-20 at rare peaks of the density field in the cold-dark-matter Universe.
		Because Population III stars probably formed individually in small mini-halos, they are not directly accessible to current telescopic studies.
	classweb.gmu.edu /kborne/csi991fall2004/abs-akash.htm (214 words)

	Abstract (Site not responding. Last check: 2007-10-09)
		The first stars to form in the universe were different from present-day stars in several ways: Firstly, due to lack of initial metals, the initial mass function could have been different, likely preferring more massive stars.
		Secondly, the absence of metal does affect the mass loss rates so that massive stars may be able to retain most of their mass till their explosive deaths and pair instability supernovae may occur.
		After giving a general overview of massive star evolution and their nucleosynthesis I will discuss the evolution of Pop III stars and pair instability supernovae.
	qso.lanl.gov /meetings/meet2004/abs_heger.html (137 words)

	Stars - Stellar Populations
		Population II stars were believed to have formed first.
		These stars occupy the globular clusters that reside in the halo of the galaxy.
		Astronomers suggest that the very first stars to ever form in the universe were Population III - that only burned hydrogen and helium only.
	astronomyonline.org /Stars/Populations.asp?Cate=Stars&SubCate=OG03&SubCate2=OG0301 (366 words)

	BBC NEWS \| Science/Nature \| Glow from first stars revealed
		Nasa scientists detected the stars from the imprint they have left on the general glow of infrared radiation dispersed throughout the cosmos.
		Energy radiated by the Population III stars must have contributed to the CIB; the problem for researchers is that many more much younger stars have also contributed.
		It is believed that these earliest stars manufactured the metals that would become important for later populations of stars.
	news.bbc.co.uk /1/hi/sci/tech/4400672.stm (573 words)

	On the properties of massive Population III stars and metal-free stellar populations
		We present realistic models for massive Population III stars and stellar populations based on non-LTE model atmospheres, recent stellar evolution tracks and up-to-date evolutionary synthesis models, with the aim to study their spectral properties, including their dependence on age, star formation history, and IMF.
		As already discussed by Tumlinson and Shull (2000), the main salient property of Pop III stars is their increased ionising flux, especially in the He
		If such stars would suffer strong mass loss, their spectral appearance could, however, remain similar to that of their ZAMS position.
	www.edpsciences.org /articles/aa/abs/2002/04/aa1629/aa1629.html (447 words)

	Biology News: Glimmer of first stars spied
		These earliest stars are known as 'population III' (after young population I stars that look like our Sun, and population II stars, which are older and more rare).
		Astronomers are intrinsically interested in these stars, which are thought to have played the initial role in the long chain of events that led to life as we know it.
		They subtracted the infrared light from all the nearby galaxies and stars, leaving behind a blotchy signal that they ascribe to the telltale clustering of population III stars.
	www.bioedonline.org /news/news.cfm?art=2135 (786 words)

	Chapter 2 Stellar Evolution Part 2 (Site not responding. Last check: 2007-10-09)
		But, as with nearby stars, the farthest ones have heavier elements (are "second-generation"), and they are not exploding any more frequently than are the nearby ones.
		All that was needed was to turn a spectroscope toward an exploded supernova and analyze the elements in the outflowing gas from the former star.
		Every star is redshifted to some extent (that is, the entire spectrum of that star is moved toward the red end).
	www.evolution-facts.org /Ev-Crunch/c02a.htm (8282 words)

	Where Are The Primordial Stars?
		Down the years, astronomers have been able to divide almost all stars into two groups: Population I, made up of young stars enriched by the products of their ancestors; and Population II, those relatively older ancestor stars containing more hydrogen and fewer heavier elements.
		Population I, according to present thinking, was formed out of the "ashes" of Population-II stars.
		What is missing from the picture are PopulationIII stars -- stars almost devoid of elements heavier than hydrogen and helium, and formed while the Big Bang was still echoing throughout the cosmos.
	www.science-frontiers.com /sf023/sf023p04.htm (191 words)

	YouDebate.com Forum > Creation Proofs - 2) Stars
		This is a rare reaction, but it occurs in massive stars as documented by the theory and shown in observations of fusion labs and particle accelerators.
		I'm sorry, I fail to see where the problem is. There is plenty of time for high mass stars to evolve in the age of the universe for an age of a star at 250 million years and the universe's age of 13.7 billion years.
		A nova is a periodic increase in brightness of a compact star that is caused by hydrogen fusion occuring at the surface.
	www.youdebate.com /cgi-bin/scarecrow/topic.cgi?forum=3&topic=1397 (8057 words)

	Image ssc2005-22b
		Eventually, around 200 to 400 million years after the Big Bang, the gas ignited and stars were born.
		The illustration shows collections of these first stars, called Population III stars, clustered together into what will later become galaxies.
		Population III stars are thought to have been incredibly massive, more than 100 times the mass of our Sun.
	www.spitzer.caltech.edu /Media/releases/ssc2005-22/ssc2005-22b.shtml (288 words)

	CBC News: Astronomers trace glow to first stars (Site not responding. Last check: 2007-10-09)
		Bottom image shows glow attributed to first stars in the universe after radiation from other stars and galaxies is removed.
		The difference is the radiation given off by the earliest stars, the researchers report in Thursday's issue of the journal Nature.
		The infrared radiation was spread across the sky unevenly, which the researchers attribute to the clumpiness of the population III stars.
	www.cbc.ca /story/science/national/2005/11/02/stars-first051102.html (500 words)

	ipedia.com: Big Bang Article (Site not responding. Last check: 2007-10-09)
		The details of how the process of galaxy formation occurred depends on the type of matter in the universe, and the three competing pictures of how this occurred are based on the properties of three types of matter known as cold dark matter, hot dark matter, and baryonic matter.
		The standard explanation for the second and third is that the universe underwent a period of massive star formation creating large high mass stars and that without heavy elements, forming low mass red dwarf stars is impossible.
		If these population III stars are found, this will strengthen the Big Bang theory.
	www.ipedia.com /big_bang_1.html (4677 words)

	Munch (Site not responding. Last check: 2007-10-09)
		We study the expected diffuse cosmic neutrino flux produced by Population III (PopIII) stars during their nuclear burning phases as well as from their final stages of evolution (core collapse).
		Assuming a fraction f_III=10^(-3) of all baryons forms PopIII stars, our flux estimate is comparable to the diffuse neutrino flux produced by the ordinary stars and by the ordinary core-collapse supernovae in the universe, i.e.
		Using simple but physically motivated recipes for identifying star forming regions, we convert gas into stars which we follow self-consistently as they impact their surroundings through supernovae and stellar winds.
	home.fnal.gov /~bertone/DM/JC112204.html (1531 words)

	4.1 Collapse scenario (Site not responding. Last check: 2007-10-09)
		The first generation of stars to form in the early universe are known as Population III stars (formed at redshifts
		Since these massive stars contained no metals, it was possible for them to form directly and then evolve with very low stellar winds and thus very little mass loss.
		Note that because these massive stars evolve so quickly (in a few million years [17]), the events associated with their deaths will take place at roughly the redshifts of their births.
	www.univie.ac.at /EMIS/journals/LRG/Articles/lrr-2003-2/node15.html (161 words)

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