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Topic: Stellar evolution


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In the News (Sun 21 Apr 19)

  
  Stellar Evolution Simulation
The above simulation shows the evolution of a star in the H-R diagram.
The total evolution of the star will take place over a period of 10 seconds, with the star spending the correct relative amount of time at each step.
You can also proceed through the evolution one step at a time using the step button.
instruct1.cit.cornell.edu /courses/astro101/java/evolve/evolve.htm   (333 words)

  
  The Role Of Stellar Population Types In The Discussion Of Stellar Evolution
In establishing a creation model of stellar (and galactic) astronomy, it is important to keep in mind the two different populations.
Several predictions of theoretical stellar evolution and purported observation- al evidences were presented without comment in that paper as well.
Armed with the results of stellar evolution it is generally argued that certain features of the H-R diagram, such as the turn off point can be used to deter- mine the age of-a- particular cluster.
www.creationresearch.org /crsq/articles/30/30_1/StellarPop.html   (3401 words)

  
  stellar evolution. The Columbia Encyclopedia, Sixth Edition. 2001-05
Thus, stellar evolution is a necessary consequence of the physical theory of stellar structure, which requires that the luminosity, temperature, and size of a star must change as its chemical composition changes because of thermonuclear reactions.
The initial phase of stellar evolution is contraction of the protostar from the interstellar gas, which consists of mostly hydrogen, some helium, and traces of heavier elements.
Because the middle age of a star is the longest period in stellar evolution, one would expect most of the observed stars to be at this stage and to show a strong correlation of luminosity with color (color is a measure of stellar temperature).
www.bartleby.com /65/st/stellare.html   (1289 words)

  
 Amazon.fr : Evolution of Stars And Stellar Populations: Livres en anglais: Maurizio Salaris,Santi Cassisi   (Site not responding. Last check: )
Evolution of Stars and Stellar Populations offers a comprehensive coverage of the links between the theory of stellar evolution and its applications to the study of stellar populations in galaxies.
The presentation of stellar evolution theory is clearly presented with particular emphasis placed on the explanations of the photometric and chemical properties of stars along their evolution as a function of their initial mass and chemical composition.
Evolution of Stars and Stellar Populations is a comprehensive presentation of the theory of stellar evolution and its application to the study of stellar populations in galaxies.
www.amazon.fr /Evolution-Stellar-Populations-Maurizio-Salaris/dp/047009219X   (473 words)

  
 Stellar Structure and Evolution
One of the triumphs of stellar evolution theory is a detailed understanding of the preferred location of stars in the physical Hertzsprung-Russell diagram, which plots luminosity versus temperature (Figure 17).
A stellar model is constructed by solving the four basic equations of stellar structure: (1) conservation of mass; (2) conservation of energy; (3) hydrostatic equilibrium and (4) energy transport via radiation, convection and/or conduction.
The evolution of a star may be followed by computing a static stellar structure model, updating the composition profile to reflect the changes due to nuclear reactions and/or mixing due to convection, and then re-computing the stellar structure model.
www.rssd.esa.int /SA-general/Projects/GAIA_files/LATEX2HTML/node64.html   (1076 words)

  
 Highbeam Encyclopedia - Search Results for stellar   (Site not responding. Last check: )
Except for that of the sun, astronomers must draw their conclusions regarding stellar structure on the basis of light and other radiation from stars that are light-years away; this light enables them to observe only the stars'...
Stellar Technologies is Ready for 2005 With a Suite of Internet Management and Security Solutions Above and Beyond Expectations.
Stellar to launch new & improved Phoenix family of automated data recovery products at GITEX, Dubai; Stellar Phoenix adds recovery strength and a NEW simple user interface to recover data from inaccessible drives and deleted folders.
www.encyclopedia.com /SearchResults.aspx?Q=stellar   (635 words)

  
 Stellar Evolution Links   (Site not responding. Last check: )
Stellar Evolution and Death provides a useful set of pages describing in summary form, the key stages in the life and death of stars.
Stellar Evolution Applet, from Victoria University in Canada allows you to compare evolutionary tracks off the main sequence for stars of different masses and metallicities.
Stellar Evolution Simulation from Cornell allows you to alter the mass of a star and see how this affects its evolutionary track from the main sequence onwards.
outreach.atnf.csiro.au /education/senior/astrophysics/stellarevolution_links.html   (1529 words)

  
 HR Diagram and Stellar Evolution
The HR diagram is important because it is the graphical interface between observation and theory in stellar evolution.
The figure has several features labeled with letters, which can be identified by stellar evolution, and the assumption that all of the stars in the cluster are about the same age (i.e., the cluster formed together).
The HR Diagram - And stellar evolution, from the Univ of Massachusetts Amherst
www.tim-thompson.com /hr.html   (2699 words)

  
 Stellar Evolution, Grand Canyon, Loch Ness Monster and Humans and Dinosaurs in Bible?
Stellar evolution is about as close to undeniable evidence as you can get.
And the ages of the stars in those nebulas is youthful, the ages of such nebulas also fall along a particular spectrum of ages as expected by the current theories of star formation.
It consists of a plot of stellar luminosity increasing upward and temperature increasing to the left...Most stars are found on a roughly diagonal band called the main sequence (MS)...
www.edwardtbabinski.us /tektonics/stellar.html   (2362 words)

  
 International Astronomical Union Symposium 246
Dense stellar systems are an interface between dynamics, stellar evolution, formation of galaxies and provide us with an ideal laboratory to understand many different aspects of these important fields as well as to explore the interplay between them.
These studies have convincingly shown that the role played by the host galaxy in the formation and evolution of star clusters is an important additional element along with the effects of stellar dynamics, stellar evolution and their complex interplay.
The complete study of the formation and evolution of star clusters is a very challenging task which requires the collaboration and the exchange of ideas of astronomers and physicists with observational and theoretical expertise in Galactic and extra-galactic astronomy, stellar dynamics, hydrodynamics and stellar evolution.
www.physics.drexel.edu /~iaus246   (225 words)

  
 Creation Science, The Age of the Universe, and Stellar Evolution
Stellar evolution is one of the most extensive disciplines of study in astrophysics; it is the study of the life cycles of stars.
The observational key to understanding stellar evolution is the ubiquitous Hertzsprung-Russell Diagram, commonly known as the "HR diagram", and also referred to as a "color magnitude" diagram by astronomers.
All of this is a congruence between stellar evolution modeling on a computer, and observations of stars, especially in clusters.
www.tim-thompson.com /stellar.html   (2188 words)

  
 stellar evolution. The Columbia Encyclopedia, Sixth Edition. 2001-05
Thus, stellar evolution is a necessary consequence of the physical theory of stellar structure, which requires that the luminosity, temperature, and size of a star must change as its chemical composition changes because of thermonuclear reactions.
The initial phase of stellar evolution is contraction of the protostar from the interstellar gas, which consists of mostly hydrogen, some helium, and traces of heavier elements.
Because the middle age of a star is the longest period in stellar evolution, one would expect most of the observed stars to be at this stage and to show a strong correlation of luminosity with color (color is a measure of stellar temperature).
www.bartelby.com /65/st/stellare.html   (1289 words)

  
 Stellar Structure & Evolution [JILA]
Peter Conti focuses on the nature and evolution of the hottest and most luminous stars in the Milky Way and other galaxies.
Jeffrey Linsky and his group investigate the role of stellar winds and interstellar gas clouds in forming astrospheres and hydrogen walls around stars.
Understanding the evolution of stellar winds with time allowed him to deduce that a strong solar wind, which appeared about 700 million years after the Sun began to shine, literally blew away the dense atmosphere of the planet Mars.
jilawww.colorado.edu /www/research/stellar.html   (1319 words)

  
 Stellar Evolution and Death -- Introduction
Examples of the latter are the formation of planetary nebulae, in which, over the course of thousands of years, a star sheds its outer layers.
In the case of supernovae, the remnant is a neutron star or a fl hole.
This article describes the evolution of stars and the dramatic events that await them during their final years of glory.
observe.arc.nasa.gov /nasa/space/stellardeath/stellardeath_intro.html   (209 words)

  
 Stellar Evolution
They are of importance in astrophysics because analysis of their orbits is the only way to directly determine stellar masses.
When a white dwarf and a red giant form a binary system, material flows from the red giant to the white dwarf, forming an accretion disc around it.
The classic book on stellar evolution is Martin Schwarzschild's Structure and Evolution of the Stars.
www.astunit.com /tutorials/stellar.htm   (948 words)

  
 Padova stellar evolutionary tracks and isochrones
Evolutionary sequences of stellar models with new radiative opacities Bressan et al.
Stellar evolutionary tracks cover the mass range from 0.7 to 100 Msun, and extend from the ZAMS up to either the beginning of the TP-AGB phase or to carbon ignition.
Stellar yields of H, He, and main CNO elements are given for stars of initial metallicities Z=0.004, Z=0.008, and Z=0.019, together with the predicted chemical abundances of planetary nebulae.
pleiadi.pd.astro.it   (1159 words)

  
 ASTR 103: Stellar - Post-Main-Sequence Evolution
From stellar models, ages can be placed along the vertical axis of an H-R diagram that correspond to the luminosity of the turnoff point for the least massive star that has reached hydrogen exhaustion, such as that shown in Figure 18.4.
Evolution for high-mass stars is very different in many respects from what we have just learned for low-mass stars.
Stellar models suggest, however, that carbon burning in some stars may start so explosively as to blow the star completely apart and is one type of supernova outburst, as suggested in Table 18.3, where we summarize evolution of all masses of stars.
physics.gmu.edu /~jevans/astr103/CourseNotes/Text/Lec05/Lec05_pt5_txt_stellarPostMSEvol.htm   (4215 words)

  
 Stellar Evolution - Black Holes
Stellar fl holes which have between 100 and 500 solar masses, usually called ‘mid-mass’ fl holes have also been found, however these are less common than their less massive counter parts (Fazekas 2004).
More commonly, stellar fl holes may be found as part of X-ray binary systems either in globular clusters or in the vicinity of galactic centers or galactic spiral arms, where they are accompanied by their respective stellar companion for example a stellar giant or low mass main sequence star.
Stellar X-ray binaries which have fl holes and radio emissions resulting from relativistic jets are sometimes referred to as to as microquasars or radio-jet X-ray binaries (Farlex Inc. 2004) to distinguish them from other stellar X-ray binaries.
astronomyonline.org /Stars/BlackHole.asp?Cate=Stars&SubCate=OG04&SubCate2=OG0405   (5984 words)

  
 Stellar evolution in the electric universe
So, at present, slow "stellar evolution" is another one of those complicated theoretical constructs that live brightly in the minds of astrophysicists without any observational evidence of their actual existence.
So, once again, in the case of stellar emission and absorption lines and their selective broadening, we observe a stellar phenomenon that is more consistent with the Electric Sun model than it is with the “fusion core” model (in which, of course, no mention is made of electric fields).
Another example of "stellar evolution" that is difficult to explain via the H-He fusion reaction is that in recent years, the centers of elliptical galaxies (the other typical location of Population II stars) have been found to emit unexpectedly high amounts of blue and ultraviolet light.
www.electric-cosmos.org /hrdiagr.htm   (7925 words)

  
 Stars Beyond Maturity
These are questions about "stellar evolution", the history of stars as they are transformed by nuclear processes deep inside.
We learn about the evolution of high-mass stars from HR diagrams of young galactic open clusters, and the evolution of low-mass metal-poor stars from old globular clusters.
Stellar luminosities and temperatures differ by such large amounts that it is necessary to use special scales in the diagram, called logarithms.
star.arm.ac.uk /~csj/astnow.html   (705 words)

  
 Stellar Evolution
These celestial bodies keep losing gas, which is blown away as a stellar wind; this mass loss is a key factor for the later evolution of the star.
The higher is the stellar mass, the smaller is the final radius of the white dwarf.
It is caused by a mechanism that appears during the evolution of the star.
www.pd.astro.it /E-MOSTRA/NEW/A3003EVO.HTM   (5025 words)

  
 SPACE.com -- Star Clusters Hold Secrets to Stellar Evolution
And against a night sky whose stellar inhabitants all appear identical, gauging even simple things about a star, such as its distance and brightness, is difficult.
That is why astronomers turn to stellar clusters, gravity-bound collections of stars all created at roughly the same time and from the same material.
Zoom in on the clusters NGC 265 and NGC 290.
www.space.com /scienceastronomy/060418_star_clusters.html   (908 words)

  
 Stellar Structure & Evolution
Their stellar evolution code has continuously been updated, reshaped and extended until the present day, still being among the top codes available.
This is a project to reduce numerical and technical uncertainties in stellar models, and to ensure that model differences are due to variations in the physics employed to calculate them.
At the Leiden Lorentz Center meeting "Fine-tuning Stellar Population Models" (June 2006) a challenge for the stellar model community was defined with the same intention.
www.mpa-garching.mpg.de /stars/index.shtml   (542 words)

  
 Stellar Evolution
Thus anyone studying the structure and evolution of stars can compute models of chosen mass and composition, and see the results (run of composition, energy generation, and gas properties with mass) presented visually as the evolution through core carbon burning proceeds.
There are programs to generate gray stellar envelopes with mixing-length convection, converge homogeneous main-sequence models, integrate evolution sequences, and create summaries of model characteristics as a function of time, including a theoretical H-R diagram.
As the evolution proceeds, the convective core shrinks as hydrogen is depleted in the core, luminosity is used to expand the envelope, the convective envelope mixes nuclear-processed material to the surface, and carbon is produced in the core.
www.nomadresearch.com /projects/aas_evol.htm   (1083 words)

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