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M. Meixner
M. Meixner

... ASYMPTOTIC GIANT BRANCH AND RED SUPERGIANT STARS: The SAGE program for the LMC obtained Color-Magnitude Diagrams (CMDs) like the one at left (e.g., Srinivasan et al 2009). RSGs are red points, Orich AGBs are blue, C-rich AGBs are purple, and extreme AGBs best fit by C-rich (O-rich) models are green ...
star pattern identification : application to the precise attitude
star pattern identification : application to the precise attitude

... The Auroral Spacecraft is one of the four satellites launched for the Interball project by the Russian Space Agency in cooperation with the international scientific community which are dedicated to magnetospheric research. This spacecraft is subject to the effects of energy exchange between the flex ...
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Massive stars as thermonuclear reactors and their explosions

Milky Way inner halo reveals its age | COSMOS magazine
Milky Way inner halo reveals its age | COSMOS magazine

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Chapter13- Star Stuff-pptx - SFA Physics and Astronomy
Chapter13- Star Stuff-pptx - SFA Physics and Astronomy

... What have we learned? • What are the life stages of a high-mass star? – They are similar to the life stages of a low-mass star. • How do high-mass stars make the elements necessary for life? – Higher masses produce higher core temperatures that enable fusion of heavier elements. • How does a high-m ...
Star Formation in the Milky Way - HubbleSOURCE
Star Formation in the Milky Way - HubbleSOURCE

... initial cloud at T=0 evolving over ~250,000 years to collapse and fragment form a small cluster of ~1200 stars. Some of the low mass members are formed in the inner cloud regions and ejected into outer regions of the ...
Chapter 9 Early stages of evolution and the main sequence phase
Chapter 9 Early stages of evolution and the main sequence phase

... know how stars are formed, how can we hope to understand their evolution? The reason that stellar evolution is a much more quantitative and predictive branch of astrophysics than star formation was already alluded to in Chapter 7. Once a recently formed star settles into hydrostatic and thermal equi ...
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... Follow the bottom most star on the left and the left most belt star upwards (going roughly over your head) and you will come across a very bright star called Capella. From Capella, you can follow the pentagon of brighter stars nearby that make up Auriga. Just below Capella, there is a triangle of st ...
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... with masses not too much different from the Sun reach this stage after using up all their hydrogen via nuclear fusion. Astrophysicists calculate that the nuclear environment in AGB stars would produce a 54Cr/52Cr ratio of about 1.1, substantially smaller than the 3.6 observed by Dauphas and coworker ...
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... We use visual and radio telescopes to observe objects in space. Visual Telescopes are called refracting and reflecting. Reflecting telescopes use mirrors and refracting telescopes use lenses to view objects far away. Radio telescopes detect the different wavelengths of objects in space. When looked ...
HR Diagram of a Star Cluster
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The Formation of High Mass Stars

... At t = 0 only source of heating is due to turbulent motions Viscous dissipation dominates heating prior to star formation After star formation commences protostellar output and accretion luminosity rather than compression and viscous dissipation is responsible for majority of radiative feedback ...
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Stellar evolution



Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.
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