Cosmic context: stars and formation of heavy elements
... Classification of stars Mass of stars ranges from ~0.1 Solar masses up to ~100 Solar masses. Low mass stars are much more common than high mass stars. Low mass stars: M < 2 Solar masses Greatest interest for astrobiology as long lived: “main sequence” lifetime (while fusing H -> He in the core) is b ...
... Classification of stars Mass of stars ranges from ~0.1 Solar masses up to ~100 Solar masses. Low mass stars are much more common than high mass stars. Low mass stars: M < 2 Solar masses Greatest interest for astrobiology as long lived: “main sequence” lifetime (while fusing H -> He in the core) is b ...
Neutron stars, pulsars
... Maximum white dwarf mass Electron degeneracy cannot support a white dwarf heavier than 1.4 solar masses This is the “Chandrasekhar limit” Won Chandrasekhar the 1983 Nobel prize in Physics ...
... Maximum white dwarf mass Electron degeneracy cannot support a white dwarf heavier than 1.4 solar masses This is the “Chandrasekhar limit” Won Chandrasekhar the 1983 Nobel prize in Physics ...
Supercomputer simulation provides missing link between turbulence, hypernovae and gamma-ray bursts
... sun, could amplify it a quadrillion (1015) times. One possibility is that energy stored in the rotation of the collapsed star could be transformed into magnetic energy. These strong magnetic fields may also be critical to help accelerate charged particles to a speed and energy able to generate a gam ...
... sun, could amplify it a quadrillion (1015) times. One possibility is that energy stored in the rotation of the collapsed star could be transformed into magnetic energy. These strong magnetic fields may also be critical to help accelerate charged particles to a speed and energy able to generate a gam ...
HR DIAGRAM[1] Star Human Comparison Are all stars the same
... From the birth of a star through most of adulthood, the star burns (fuses) hydrogen in order to maintain equilibrium. There are small adjustments made to maintain Main Sequence status, but these changes are only to maintain balance between gravity and gas pressure. A star spends most of its life in ...
... From the birth of a star through most of adulthood, the star burns (fuses) hydrogen in order to maintain equilibrium. There are small adjustments made to maintain Main Sequence status, but these changes are only to maintain balance between gravity and gas pressure. A star spends most of its life in ...
Properties of Stars and H
... Which Star is Brighter? • From Earth, both stars A and B seem like they have the same brightness. • Because we see this from earth, we say that the apparent magnitude is the same. • In reality, Star B is far brighter, but it is just farther away. • We would say that the actual magnitude of star B i ...
... Which Star is Brighter? • From Earth, both stars A and B seem like they have the same brightness. • Because we see this from earth, we say that the apparent magnitude is the same. • In reality, Star B is far brighter, but it is just farther away. • We would say that the actual magnitude of star B i ...
1st EXAM VERSION C - Department of Physics and Astronomy
... D. the amount of mass in the cloud alone, because this determines the strength of gravity, which will act unopposed on the cloud 41. Which one of the following statements is correct for an isolated star (i.e., a star that is not in a binary star system A. *It is not possible to measure the star's ma ...
... D. the amount of mass in the cloud alone, because this determines the strength of gravity, which will act unopposed on the cloud 41. Which one of the following statements is correct for an isolated star (i.e., a star that is not in a binary star system A. *It is not possible to measure the star's ma ...
Phys 214. Planets and Life
... supernova, widely seen on Earth beginning in the year 1006 AD; Earth was about 7200 light-years away. Egyptian astrologer left us a historical description of the supernova - the object was 2-1/2 to three times as large as the disc of Venus, and about one-quarter the brightness of the Moon. ...
... supernova, widely seen on Earth beginning in the year 1006 AD; Earth was about 7200 light-years away. Egyptian astrologer left us a historical description of the supernova - the object was 2-1/2 to three times as large as the disc of Venus, and about one-quarter the brightness of the Moon. ...
1. If a star`s temperature is doubled but radius is kept constant, by
... 12. True or False: Stars on the upper main sequence are more massive than stars on the lower main sequence. 12a. True. 13. True or False: What can explain the luminosity difference between a white dwarf of spectral type A and a Supergiant of spectral type A? 13a. The Supergiant is larger. 14. True o ...
... 12. True or False: Stars on the upper main sequence are more massive than stars on the lower main sequence. 12a. True. 13. True or False: What can explain the luminosity difference between a white dwarf of spectral type A and a Supergiant of spectral type A? 13a. The Supergiant is larger. 14. True o ...
Before Humankind - Salem State University
... for billions of years. When hydrogen atoms in their core fuse together under pressure and heat, they become helium atoms. This process is called fusion. After billions of years stars cool and collapse and become supernova. Debris from their collapse heats up again and a cloud of hot hydrogen and hel ...
... for billions of years. When hydrogen atoms in their core fuse together under pressure and heat, they become helium atoms. This process is called fusion. After billions of years stars cool and collapse and become supernova. Debris from their collapse heats up again and a cloud of hot hydrogen and hel ...
Life Cycle of Stars
... • Begin their lives as clouds of dust and gas called nebulae • Gravity may cause the nebula to contract • Matter in the gas cloud will begin to condense into a dense region called a protostar • The protostar continues to condense, it heats up. Eventually, it reaches a critical mass and nuclear fusio ...
... • Begin their lives as clouds of dust and gas called nebulae • Gravity may cause the nebula to contract • Matter in the gas cloud will begin to condense into a dense region called a protostar • The protostar continues to condense, it heats up. Eventually, it reaches a critical mass and nuclear fusio ...
Distribution of Elements in the Earth`s Crust
... The universe began about 13.8 billion years ago with the big bang, an event in which enormous quantities of energy and matter—consisting primarily of the elements hydrogen and helium—started expanding into what today we think of as space. Over time, hydrogen and helium particles coalesced into dense ...
... The universe began about 13.8 billion years ago with the big bang, an event in which enormous quantities of energy and matter—consisting primarily of the elements hydrogen and helium—started expanding into what today we think of as space. Over time, hydrogen and helium particles coalesced into dense ...
Unit 11 Vocabulary
... hydrogen fuel, and is in the last stage of its life. 6. red supergiant star - the largest stars in the universe in terms of volume, although they are not the most massive. Betelgeuse and Antares are the brightest and best known red supergiants. 7. white dwarf star – this is what stars like the Sun b ...
... hydrogen fuel, and is in the last stage of its life. 6. red supergiant star - the largest stars in the universe in terms of volume, although they are not the most massive. Betelgeuse and Antares are the brightest and best known red supergiants. 7. white dwarf star – this is what stars like the Sun b ...
Astronomy Exam #2 for the 10
... Use the HR diagram below to answer the following questions. Note: No calculations are needed. ...
... Use the HR diagram below to answer the following questions. Note: No calculations are needed. ...
Four Homework Assignments
... radius (R), assuming Kramers opacity, and using the ideal gas law, derive a very approximate R(M ) for main-sequence stars from ∼1.5 M to 4.0 M . [Hint: You will need to know whether hydrogen burning is proceeding by the PP chain or the CNO cycle.] Retain the µ dependence of your result. What powe ...
... radius (R), assuming Kramers opacity, and using the ideal gas law, derive a very approximate R(M ) for main-sequence stars from ∼1.5 M to 4.0 M . [Hint: You will need to know whether hydrogen burning is proceeding by the PP chain or the CNO cycle.] Retain the µ dependence of your result. What powe ...
Due: January 14, 2014 Name: White dwarfs are “has been
... The energy radiated from a protostar comes from gravitational potential energy that is converted to kinetic and then thermal energy when the matter within the protostar falls toward the core. The energy radiated by a main-sequence star comes from nuclear fusion. ...
... The energy radiated from a protostar comes from gravitational potential energy that is converted to kinetic and then thermal energy when the matter within the protostar falls toward the core. The energy radiated by a main-sequence star comes from nuclear fusion. ...
STELLAR EVOLUTION
... Computational models which predict the lifetimes and properties of stars of all masses. Astronomers then match these predictions with observed populations of stars, especially the stars found within clusters. Observations of the temperature, density, and motions of interstellar gas and dust clou ...
... Computational models which predict the lifetimes and properties of stars of all masses. Astronomers then match these predictions with observed populations of stars, especially the stars found within clusters. Observations of the temperature, density, and motions of interstellar gas and dust clou ...
Type II supernova
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times, the mass of the Sun (M☉) for this type of explosion. It is distinguished from other types of supernovae by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures, causing increasingly shorter stellar life spans. The degeneracy pressure of electrons and the energy generated by these fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with hydrogen and then helium, progressing up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel-iron core inert. Due to the lack of energy output allowing outward pressure, equilibrium is broken.When the mass of the inert core exceeds the Chandrasekhar limit of about 1.4 M☉, electron degeneracy alone is no longer sufficient to counter gravity and maintain stellar equilibrium. A cataclysmic implosion takes place within seconds, in which the outer core reaches an inward velocity of up to 23% of the speed of light and the inner core reaches temperatures of up to 100 billion kelvin. Neutrons and neutrinos are formed via reversed beta-decay, releasing about 1046 joules (100 foes) in a ten-second burst. The collapse is halted by neutron degeneracy, causing the implosion to rebound and bounce outward. The energy of this expanding shock wave is sufficient to accelerate the surrounding stellar material to escape velocity, forming a supernova explosion, while the shock wave and extremely high temperature and pressure briefly allow for theproduction of elements heavier than iron. Depending on initial size of the star, the remnants of the core form a neutron star or a black hole. Because of the underlying mechanism, the resulting nova is also described as a core-collapse supernova.There exist several categories of Type II supernova explosions, which are categorized based on the resulting light curve—a graph of luminosity versus time—following the explosion. Type II-L supernovae show a steady (linear) decline of the light curve following the explosion, whereas Type II-P display a period of slower decline (a plateau) in their light curve followed by a normal decay. Type Ib and Ic supernovae are a type of core-collapse supernova for a massive star that has shed its outer envelope of hydrogen and (for Type Ic) helium. As a result, they appear to be lacking in these elements.