Fe I/Fe II ionization equilibrium in cool stars: NLTE versus LTE
... 965 energy levels for Fe I. A comparison with the calculated Fe I atomic structure (Kurucz (2007)) reveals that the system of measured levels is nearly complete below excitation energy, Eexc , 5.6 eV, however, laboratory experiments do not see most of the highexcitation levels with Eexc > 7.1 eV. As ...
... 965 energy levels for Fe I. A comparison with the calculated Fe I atomic structure (Kurucz (2007)) reveals that the system of measured levels is nearly complete below excitation energy, Eexc , 5.6 eV, however, laboratory experiments do not see most of the highexcitation levels with Eexc > 7.1 eV. As ...
Evolved Stellar Populations
... how is it measured? Age Stars in a specific evolutionary phase. Fit of the main-sequence turn-off. Metallicity Metallic lines from stars and nebula Ca II triplet Fit of isochrones/cluster tracks to a CMD C/M ratio Kinematics Atomic and molecular lines ...
... how is it measured? Age Stars in a specific evolutionary phase. Fit of the main-sequence turn-off. Metallicity Metallic lines from stars and nebula Ca II triplet Fit of isochrones/cluster tracks to a CMD C/M ratio Kinematics Atomic and molecular lines ...
Closing in on Black Holes
... – Posed a theoretical question about a star • At what radius of star, like the Sun, would the escape velocity exceed the speed of light? ...
... – Posed a theoretical question about a star • At what radius of star, like the Sun, would the escape velocity exceed the speed of light? ...
Nebula Beginnings - University of Dayton
... of stars far more massive than our Sun. The precursor star to this remnant, which was located slightly below and left of center in the image, is estimated to have been 25 times the mass of our Sun. These stars "cook" heavier elements through nuclear fusion, including oxygen, nitrogen, carbon, iron e ...
... of stars far more massive than our Sun. The precursor star to this remnant, which was located slightly below and left of center in the image, is estimated to have been 25 times the mass of our Sun. These stars "cook" heavier elements through nuclear fusion, including oxygen, nitrogen, carbon, iron e ...
docx - STAO
... colour) and the distance from the observer. Sometimes the brightest-looking stars are not actually the brightest, and sometimes the closest-looking stars are not the closest. Light energy dissipates (spreads out) as it travels from its source. You could briefly discuss the idea of the inverse square ...
... colour) and the distance from the observer. Sometimes the brightest-looking stars are not actually the brightest, and sometimes the closest-looking stars are not the closest. Light energy dissipates (spreads out) as it travels from its source. You could briefly discuss the idea of the inverse square ...
Presidential
... Chandrasekhar's work: Star collapse and Stable Configuration Limit Continual Collapse for Massive Stars What is the Final End state of such a Continual Collapse? ...
... Chandrasekhar's work: Star collapse and Stable Configuration Limit Continual Collapse for Massive Stars What is the Final End state of such a Continual Collapse? ...
Star Composition: Flame Testing Lab S-2
... 8th grade science standards: b. Students know that the Sun is one of many stars in the Milky Way galaxy and that stars may differ in size, temperature, and color. d. Students know that stars are the source of light for all bright objects in outer space and that the Moon and planets shine by reflecte ...
... 8th grade science standards: b. Students know that the Sun is one of many stars in the Milky Way galaxy and that stars may differ in size, temperature, and color. d. Students know that stars are the source of light for all bright objects in outer space and that the Moon and planets shine by reflecte ...
21. The Milky Way Galaxy
... the stars are luminous super giants and only a few 10s of millions years old. ...
... the stars are luminous super giants and only a few 10s of millions years old. ...
- Europhysics News
... quest: at those distances, only the most luminous stars have a chance to be separated from the herd. The infrared image of Fig. 1, taken at 3700 nm gives an idea of the crowding in a field of only a few light-years around SgrA*. Even this picture is far from fully expressing the reality since only o ...
... quest: at those distances, only the most luminous stars have a chance to be separated from the herd. The infrared image of Fig. 1, taken at 3700 nm gives an idea of the crowding in a field of only a few light-years around SgrA*. Even this picture is far from fully expressing the reality since only o ...
Lab: Heliocentric Parallax
... 1. Calculate the amount that each star has moved horizontally (in grid units) and fill in the X2-X1 column 2. Calculate the amount that each star has moved vertically (in grid units) and fill in the ...
... 1. Calculate the amount that each star has moved horizontally (in grid units) and fill in the X2-X1 column 2. Calculate the amount that each star has moved vertically (in grid units) and fill in the ...
Ridgway - Betelgeuse Workshop 2016
... Unexpectedly large mass loss during the thermal pulse cycle of the red giant star R Sculptoris, M. Maercker, Elizabeth Humphreys et al., Nature 490, 232 (2012) ...
... Unexpectedly large mass loss during the thermal pulse cycle of the red giant star R Sculptoris, M. Maercker, Elizabeth Humphreys et al., Nature 490, 232 (2012) ...
form b - University of Iowa Astrophysics
... distance to more distant galaxies than Cepheid variables? (a) SN Type Ia explosions only occur in the most distant galaxies. (b) Cepheid variables change their brightness too quickly to detect at great distances. (c) Most galaxies in the universe are elliptical and don’t have Cepheid variables. (d) ...
... distance to more distant galaxies than Cepheid variables? (a) SN Type Ia explosions only occur in the most distant galaxies. (b) Cepheid variables change their brightness too quickly to detect at great distances. (c) Most galaxies in the universe are elliptical and don’t have Cepheid variables. (d) ...
Spectrum, Red Shift, Blue Shift
... vary in length from very long (radio waves) to incredibly short (gamma rays). A special part of the spectrum consists of waves that we can see. This is called the _____________________________. We see different wavelengths as different colors ranging from red (_____________________) to blue/violet ( ...
... vary in length from very long (radio waves) to incredibly short (gamma rays). A special part of the spectrum consists of waves that we can see. This is called the _____________________________. We see different wavelengths as different colors ranging from red (_____________________) to blue/violet ( ...
Untitled
... stars around the edge of the cluster. Though it appears near the SMC it is onetenth the distance, 15 000 light years away, and is has no connection to the Small Cloud. Globular clusters are mostly very old, 10 billion years or more; at least twice the age of the sun. Omega Centauri, above and left o ...
... stars around the edge of the cluster. Though it appears near the SMC it is onetenth the distance, 15 000 light years away, and is has no connection to the Small Cloud. Globular clusters are mostly very old, 10 billion years or more; at least twice the age of the sun. Omega Centauri, above and left o ...
Lecture 18 Gamma-Ray Bursts
... and HETE-2 and coordinated searches for counterparts were carried out. The bursts were GRB 050509b (z = 0.2248, elliptical galaxy), 050709 (z = 0.161) and 050724 (z = 0.258) The bursts were either on the outskirts of galaxies or in old galaxies with low star formation rate There was no accompanying ...
... and HETE-2 and coordinated searches for counterparts were carried out. The bursts were GRB 050509b (z = 0.2248, elliptical galaxy), 050709 (z = 0.161) and 050724 (z = 0.258) The bursts were either on the outskirts of galaxies or in old galaxies with low star formation rate There was no accompanying ...
Physics@Brock - Brock University
... (a) About 50% hydrogen, about 50% helium, and less than 2% heavier elements. (b) About 60% hydrogen, about 40% helium, and less than 2% heavier elements. (c) About 75% hydrogen, about 25% helium, and less than 2% heavier elements. (d) About 90% hydrogen, about 10% helium, and less than 2% heavier el ...
... (a) About 50% hydrogen, about 50% helium, and less than 2% heavier elements. (b) About 60% hydrogen, about 40% helium, and less than 2% heavier elements. (c) About 75% hydrogen, about 25% helium, and less than 2% heavier elements. (d) About 90% hydrogen, about 10% helium, and less than 2% heavier el ...
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.