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Topic: Population I stars

	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.
		One theory, which seems to be borne out by computer models of star formation, is that with no heavy elements from the Big Bang, it was easy to form stars much more massive than the ones visible today.
		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.
	en.wikipedia.org /wiki/Population_III_stars (485 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_populations (382 words)

	AllRefer.com - stellar populations (Astronomy, General) - Encyclopedia (Site not responding. Last check: 2007-10-12)
		Population II stars are formed early in the history of the galaxy from pure hydrogen with an admixture of primordial helium.
		Population I stars, of which the sun is typical, are young stars that still lie mostly on the main sequence of the Hertzsprung-Russell diagram.
		Population II stars are found both in the spiral arms and in the gas-free and dust-free regions of the spiral galaxies, i.e., the nucleus and the halo of high-velocity stars and globular clusters that surround the disk of the galaxy.
	reference.allrefer.com /encyclopedia/S/stellarp.html (455 words)

	The Role Of Stellar Population Types In The Discussion Of Stellar Evolution
		A star's space velocity can be expressed in terms of two component velocities with respect to the solar system: the radial velocity in the line of sight to the star, and the tangential velocity perpendicular to the radial velocity.
		This suggests that the sun is a population I star, and that population I stars orbit the galactic center in roughly circular orbits confined to the galactic plane.
		Open star clusters have high metal abundances and are found near the galactic plane, and so are recognized as population I. Population I stars generally have clouds of dust and gas around and near them, while population II stars generally are found in dust free and gas free environments.
	www.creationresearch.org /crsq/articles/30/30_1/StellarPop.html (3401 words)

	Stellar Populations (Site not responding. Last check: 2007-10-12)
		Extreme Population I stars (the most metal rich stars) are found only in the spiral arms; these are the youngest stars.
		Population II stars are metal poor stars; they contain about 0.1 percent metals.
		Extreme Population II stars (the most metal poor) are found in the halo and the globular clusters; these are the oldest stars.
	www.astro.umd.edu /education/astro/mw/pop.html (432 words)

	Fixed Stars (Site not responding. Last check: 2007-10-12)
		Population II is represented by the globular clusters, of which Messier 13 in Hercules is one of the best examples.
		Before star formation started, the universe was composed almost entirely of hydrogen and helium, so that the very first stars must have been quite free from heavy elements.
		Stars of this sort, which have yet to be found in their purest state, have been referred to as population III.
	www.mira.org /sky/summer.htm (1455 words)

	Population I and II Stars (Site not responding. Last check: 2007-10-12)
		Stars may be classified by their heavy element abundance, which correlates with their age and the type of galaxy in which they are found.
		Population I stars include the sun and tend to be luminous, hot and young, concentrated in the disks of spiral galaxies.
		About 2% of the total belong to Population I. Population II stars tend to be found in globular clusters and the nucleus of a galaxy.
	hyperphysics.phy-astr.gsu.edu /hbase/starlog/pop12.html (142 words)

	stars
		Population I stars tend to live near the galactic plane, and hence the spiral arms are mainly these stars.
		Recall that the bigger the magnitude, the dimmer the star, and that magnitude is a logarithmic scale, with 5 magnitudes corresponding to a factor of 100.
		The stars are unusually rich in carbon and it is thought that this element plays a similar role in the star's atmosphere to that of water vapor in the atmosphere of the Earth, condensing to form clouds that obscure the sky unless they disappear in the form of rain.
	math.ucr.edu /home/baez/stars.html (3344 words)

	intermediate population star
		A star with properties between those of extreme Population I stars in the galactic spiral arms and extreme Population II stars in the galactic halo.
		Intermediate population I stars move in circular orbits but are distributed throughout the galactic disk not just in the arms.
		Intermediate population II stars outside of the halo are not confined to circular orbits or to the disk, instead moving in moderately elliptical orbits though still centered on the galactic nucleus.
	www.daviddarling.info /encyclopedia/I/intermediate_population_star.html (242 words)

	Interstellar Medium and the Milky Way
		Population I star orbits are orderly: roughly circular orbits close to the mid-plane of the galactic disk.
		Stars less than 100 million years old are found in the spiral arms within 400 light years of the disk plane.
		Recent measurements of the tangential motion of the stars close to the center show that the radial velocities measured are for stars moving in circular orbits---that means that the doppler shifts measured are indeed those expected for a super-massive fl hole (or compact star cluster) with about 2.5 million solar masses.
	www.astronomynotes.com /ismnotes/s9.htm (1018 words)

	Lecture 8 Question 4
		Population II stars, on the other hand, are located in the central bulge or in the halo part of the galaxy.
		Stars in each population are quite similar except for the fact that the stars in population I have more metals heavier than helium than their metal poor, population II counterparts.
		Astronomers have also observed that population I stars are relatively young stars that have circular orbits in the plane of the galaxy while population II stars are typically old stars that do not have circular orbits rather elliptical orbits.
	hyper.vcsun.org /HyperNews/rrains/get/DQ8g/6.html (261 words)

	THE INFINITE UNIVERSE Chapter 4-4
		Population I stars, with stronger concentrations of heavy elements in their outer star regions, may have gotten more dust during their formation, which may make them different from Population II stars.
		Population II stars originating in the bulge may be explained by gas and (smaller) dark matter objects entering the bulge as well as dark matter debris produced by (larger) clashing dark matter objects.
		Population II stars in the halo of our Galaxy have very low metal abundances, which may be because dust and dark matter is not concentrated in the halo as it is in the spiral arms, and: dust comes later to the stars then hydrogen (4-3).
	www.eitgaastra.nl /timesgr/part4/4.html (17834 words)

	Encyclopedia Galactica - Po - Human (Anglic) Revised 351st Edition
		Stars with a few percent heavy elements (heavier than helium), found in the disks of spiral galaxies and in irregular galaxies.
		Population II Stars composed of nearly pure hydrogen and helium, found in globular clusters (galactic halo) and the center of spiral galaxies, in elliptical galaxies, and to a limited extent in irregular galaxies.
		Their existence was theorised during the atomic age as an attempt to describe the metallicity present in population II stars where nucleosynthesis should not have been able to produce heavy elements.
	www.orionsarm.com /eg/p/Po-Pq.html (3215 words)

	stellar populations
		Population I stars, of which the sun is typical, are young stars that still lie mostly on the main sequence of the
		Because they are second-generation stars formed from the debris of exploded population II stars, population I stars have a considerable content of heavy elements that were created by
		Population I stars are located in the disk singly and in galactic, or open,
	www.factmonster.com /id/A0846632 (438 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)

	HighBeam Encyclopedia - stellar populations (Site not responding. Last check: 2007-10-12)
		STELLAR POPULATIONS [stellar populations] two broadly contrasting distributions of star types that are characteristic of different parts of a galaxy.
		Free-floating planets and stellar clusters: Scientists have been looking for planets in strange places, far from their parent stars, within some of the densest star clusters in the Galaxy.
		Performance of doubled haploid populations segregating for linolenic acid levels in spring rapeseed.
	www.encyclopedia.com /html/s1/stellarp.asp (639 words)

	ASTRONOMY CLASS DISCUSSION (Site not responding. Last check: 2007-10-12)
		It is because of angular momentum—the turning motion (revolutions) of stars, binaries, planets, moons, and galaxies, along with their orbits around other bodies (rotations), that they are able to maintain their precise relationships to one another—without all crashing together or flying apart.
		The first is that many of the first generation of stars (Population III stars) exploded, producing second and third generation stars (Population I and II) which have heavy metals—elements above hydrogen and helium.
		The mass-luminosity law requires that the brightest, hottest stars burn themselves out the fastest,—yet they are all found together in the same galaxy, and there is no evidence that new stars are being formed.
	www.pathlights.com /ce_encyclopedia/03-ss6.htm (1544 words)

	Galactic archaeology (Site not responding. Last check: 2007-10-12)
		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.
		However, in the most primitive stars which have been discovered more recently, the strontium and barium contents are more reminiscent of the s-process, even though this is not expected to have operated so early in the history of the Galaxy, when these stars were still forming.
	physics.open.ac.uk /~sgryan/an00.html (2668 words)

	A Brief Stellar History (Site not responding. Last check: 2007-10-12)
		A star is a sphere of gas, which ordinarily would contract under its own weight were it not for the pressure of both the gases and the radiation it produces.
		The largest stars of this type are the cool red giants with vast, tenuous outer layers, which contrasts with their highly condensed cores.
		As may be inferred from the foregoing discussion, the Vc model accepts the usual mechanism for the ageing of the stars, and the consequent appearance of the various stars is explicable in terms of known processes.
	www.setterfield.org /stellarhist.html (11360 words)

	Field stars (Site not responding. Last check: 2007-10-12)
		Metals are distinctively less abundant in these stars than in the disk stars and there is no gas or dust in their environments.
		The metal richness in of Population I stars suggests that they formed from the debris of earlier generations of stars (possibly Population II).
		It is difficult to determine the distribution of stars because of obscuration by dust.
	www.astro.soton.ac.uk /~crk/PH227/node15.html (318 words)

	BioEd Online: 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-print.cfm?art=2135 (699 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.
		When that cloud undergoes contraction and give birth to a new star, the end result is a Population I star - one that is now metal rich.
	astronomyonline.org /Stars/Populations.asp?Cate=Stars&SubCate=OG03&... (366 words)

	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.
	innovations-report.com /html/reports/.../report-16023.html (761 words)

	Antanas Bartkevicius Home Page
		Population II binaries: compilation of catalogs, photometric properties and classification, radial velocities
		Progress report on the radial velocity measurement programme of population II stars.
		Catalogue of population II A-F supergiants: UU Herculis and related stars.
	www.itpa.lt /~bart (225 words)

	Main Sequence of Disk Population F Stars from HIPPARCOS Data (Site not responding. Last check: 2007-10-12)
		The age effect in metallicity groups of stars have been found to manifest itself in larger velocity dispersion in the middle of the MS band (locus of turnoff points), with the dispersion being larger at same effective temperature for metal poor groups, and increasing toward cooler stars within a group.
		This may be consistent with larger helium abundance in metal rich stars, although the amount of required helium enrichment may be uncomfortably large.
		A large width of the MS of metal poor stars at the red end may be indicative of an additional factor (``fourth parameter''?) to widen the MS band because both the kinematics and the isochrone turnoff age for the stars here look to be incompatible with age widening.
	www.aas.org /publications/baas/v29n5/aas191/abs/S014006.html (318 words)

	stellar populations (Site not responding. Last check: 2007-10-12)
		Free-floating planets and stellar clusters: Scientists have been looking for planets in strange places, far from their parent stars,......
		Estimating the large-scale structure of the universe using quasi-stellar object carbon IV absorbers.
		China's demographic destiny and its economic implications: population changes will impact China's long-term economic growth and global......
	www.infoplease.com /ce6/sci/A0846632.html (579 words)

	Catalogue: J/other/BaltA/5.1/tables
		Methods Bartkevicius A., Lazauskaite R. Astronomy, 5, 1 (1996)> =1996BaltA...5....1B ================================================================================ ADC_Keywords: Stars, population II ; Photometry, Vilnius ; Abundances, [Fe/H] Keywords: photometry - stars: fundamental parameters - stars: population II Description: The astrophysical parameters compiled from literature for 809 stars of different types, mainly Population II stars, are presented.
		Coding of identification numbers is explained in General Photometric Catalogue of Stars Observed in the Vilnius System (Straizys and Kazlauskas, 1993BaltA...2....1S).
		CPM: Comon proper motion Var RV: Variable radial velocity Var RV?: Suspected variable radial velocity VAR: Variable star, P is the period in days, V, PG and B are the corresponding magnitudes in maximum and minimum.
	vizier.u-strasbg.fr /cgi-bin/Cat?J/other/BaltA/5.1/tables (508 words)

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