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The Saha Equation
The Saha Equation

Document
Document

... the metals, and I have no doubt that the number of hydrogen atoms in the two quantum state is enormously greater than is indicated by the theory of Fowler and Milne. „ Henry Norris Russell in a letter to CPG Later Russell reversed his position after seeing new analysis of the sun an wrote a paper “O ...
Star Life Cycle
Star Life Cycle

... break down these three according to a slight variation in shape between each type of galaxy in each category. For the "E" or 5)_________________galaxies, he used the amount of flattening or 6)_____________, from E0( E zero) to E5, to put the galaxies into smaller groups. For the "S" or 7)___________ ...
The Milky Way Galaxy - Academic Computer Center
The Milky Way Galaxy - Academic Computer Center

... collapse of gas clouds causing new stars to form. • The process continues as new large stars explode causing more clouds to collapse. • As these stars orbit the galaxy the stars closer in orbit faster and form a spiral shape. • This is called selfpropagating star formation or SSF. ...
Study Guide for the Final Exam
Study Guide for the Final Exam

... Astronomy 5 - Study Guide for the Final Exam Here is a guide to help you focus on the important aspects of the chapters of the text covering material from our coverage of the Nebular Hypoothesis on. Use this guide in conjunction with the PREVIOUS GUIDES, in-class Quizzes and the Review Questions, wh ...
1.3. Basic Principles of Nuclear Physics
1.3. Basic Principles of Nuclear Physics

... Accretion of the atmosphere (mostly H, He) of expanding star on the compact object Ignition of the unburnt H ...
How Did We Wind Up in Such an Unlikely Universe?
How Did We Wind Up in Such an Unlikely Universe?

Searching for stars in high-velocity clouds
Searching for stars in high-velocity clouds

Gravitationally redshifted absorption lines in the x
Gravitationally redshifted absorption lines in the x

... Absorption features in burst spectra are very sensitive to the accretion rate, temperatures, density, and rotation frequency of the neutron star (Bildsten et al. 2003; Chang et al. 2005, ...
P10263v1.2 Lab 5 Text
P10263v1.2 Lab 5 Text

... Astronomers have also studied stars like those found in the Pleiades, and from this collection of “standard stars”, they have determined how the size varies with star color (bluer, hotter stars tend to be somewhat larger than stars like the Sun). This information about the sizes and temperatures of ...
The s-process in low metallicity stars - GSI
The s-process in low metallicity stars - GSI

... Three s-process components were anticipated by the classical analysis (Clayton and Rassbach 1974; Kaeppeler et al. 1982): the weak, the main, and the strong s-component. The main s-component is the outcome of many generations of Asymptotic Giant Branch stars (AGB) polluting the interstellar medium ...
Finding the Mass of an Exoplanet
Finding the Mass of an Exoplanet

Boltmann/Saha Equation Examples
Boltmann/Saha Equation Examples

... state. So, we are asking how many different states j are there with the same energy Ej ? In this problem, we are comparing the only possible ionization states of Hydrogen: neutral and singly ionized (HII). Since a hydrogen ion is just a proton, there is only one possible energy state so gr+1 = 1. Ne ...
What is the minimum size of a star that will go supernova? A. Half
What is the minimum size of a star that will go supernova? A. Half

... A. Half the mass of the Sun  B. Eight times the mass of the Sun  C. Twice the mass of the Sun  Answer:  B. Eight times the mass of  the Sun  Stars with less than 8 times the mass  of the sun will end their lives as a  white dwarf.   ...
Tolman–Oppenheimer–Volkoff (TOV) Stars
Tolman–Oppenheimer–Volkoff (TOV) Stars

... time, a phenomenon made possible by the balance of internal pressure support against the star’s gravitational field. For stars like our sun the gas pressure is fueled by the hot nuclear reactions in its core. However, many types of stars are known to exist with varying mass and temperature as charac ...
Slide 1
Slide 1

... i. If a collapsing star of over 3 solar masses does not eject matter, it becomes a black hole. ii. a mass of an order of magnitude between 105 and 1010 of solar masses. Most, if not all galaxies, including the Milky Way, contain supermassive black holes at their galactic centers. 7. Dark Matter and ...
Astrophysical explosions: from solar flares to cosmic gamma
Astrophysical explosions: from solar flares to cosmic gamma

... therefore a muted tendency to expand and cool adiabatically. Because the hotter matter burns more quickly, ignition under conditions of electron degeneracy leads to a thermal instability. By the time the hydrogen layer is hot enough that the degeneracy is lifted, the thermonuclear burning time scale ...
chap11 (WP)
chap11 (WP)

Early stages of clustered star formation -massive dark clouds
Early stages of clustered star formation -massive dark clouds

... exist in approximate pressure (P) equilibrium with each other, i.e., the product of the density (n) and temperature (T) in each phase is constant (P ∼ nT ≈ 104 cm−3 K). These are the hot coronal and intercloud gas (n < 10−2 cm−3 , T ∼ 106 K); the warm, neutral and ionised gas (n ∼ 0.1–10 cm−3 , T ∼ ...
GALEX UV Light-curves of M-Dwarf Flare Stars: THE FLARING UV
GALEX UV Light-curves of M-Dwarf Flare Stars: THE FLARING UV

... Barry Welsh, Jonathan Wheatley & Stanley Browne ...
color-stellar mass diagram
color-stellar mass diagram

Section 2: Applet Walkthrough
Section 2: Applet Walkthrough

... As we have seen, in the Star Selection box (lower left) you can choose which stars you want plotted on the diagram. There is also a Find feature that can be used to locate a specific star in the database of stars already in the applet (25 brightest stars and 34 nearest stars) or a userdefined star. ...
Black Holes
Black Holes

... gravity by the star’s mass. But when a star is in its death throes, the fusion reactions combining hydrogen into helium (like in the Sun) stop and a new kind of nuclear reaction take place that convert helium into carbon. This is followed by carbon turning into oxygen and oxygen to silicon and then ...
Sco
Sco

... Be stars are rapidly rotating non-supergiant objects of spectral type B that sometimes show hydrogen emission lines in their spectra ...
ASTR100 Class 01 - University of Maryland Department of
ASTR100 Class 01 - University of Maryland Department of

... channels, a few percent of the "snow" that you see on your screen is noise caused by the background of microwaves… ...
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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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