Homework #2 1. There are two ways to estimate the energy carried
... longer than the gravitational free-fall time of the cloud, tf f ≈ 1/ Ghρi, where hρi is the mean density of the cloud. What happens if tKH < tf f ? b) Estimate the critical radius Rc (in R ) at which tKH ≈ tf f , i.e, at which KH contraction begins, for a given cloud of mass M (in M ). Assume, as ...
... longer than the gravitational free-fall time of the cloud, tf f ≈ 1/ Ghρi, where hρi is the mean density of the cloud. What happens if tKH < tf f ? b) Estimate the critical radius Rc (in R ) at which tKH ≈ tf f , i.e, at which KH contraction begins, for a given cloud of mass M (in M ). Assume, as ...
Week 3 - OSU Astronomy
... Outer part is hot enough to destroy dust, molecules, and ionize gas has enough energy to produce expanding bubble in birth cloud The most massive stars are about 120 solar masses It seems stars cannot stay together at higher masses - pressure beats gravity! ...
... Outer part is hot enough to destroy dust, molecules, and ionize gas has enough energy to produce expanding bubble in birth cloud The most massive stars are about 120 solar masses It seems stars cannot stay together at higher masses - pressure beats gravity! ...
Link again
... Stars can form in groups called “clusters.” Open clusters are relatively young. The Pleiades formed about 100 million years ago and the gas and dust from which they formed still surrounds them. Globular clusters contain thousands of stars and are usually around 10 billion years old. Stars begin as c ...
... Stars can form in groups called “clusters.” Open clusters are relatively young. The Pleiades formed about 100 million years ago and the gas and dust from which they formed still surrounds them. Globular clusters contain thousands of stars and are usually around 10 billion years old. Stars begin as c ...
The woman who dissected the Sun
... "discrete" orbits and emit or absorb light when they jump from one orbit to another. Crucially, an electron can absorb enough energy to be kicked out of an atom altogether. The connection with hot bodies like stars was made in 1920 by an Indian physicist called Meghnad Saha who combined quantum theo ...
... "discrete" orbits and emit or absorb light when they jump from one orbit to another. Crucially, an electron can absorb enough energy to be kicked out of an atom altogether. The connection with hot bodies like stars was made in 1920 by an Indian physicist called Meghnad Saha who combined quantum theo ...
Document
... Gravity compresses a cloud of H and He gas The gas particles get closer and closer The volume of the gas cloud decreases As they get closer they move faster Temperature and pressure increase ...
... Gravity compresses a cloud of H and He gas The gas particles get closer and closer The volume of the gas cloud decreases As they get closer they move faster Temperature and pressure increase ...
A Stellar Astronomy Toolbox 9
... Where T is the temperature and k is the boltzman constant (k = 1.38 x 10-23 J/K). So what is important here? The higher the average kinetic energy of a group of particles, the higher the temperature. They are directly proportional. Why does a stove burner feel hot? When a stove burner has a high tem ...
... Where T is the temperature and k is the boltzman constant (k = 1.38 x 10-23 J/K). So what is important here? The higher the average kinetic energy of a group of particles, the higher the temperature. They are directly proportional. Why does a stove burner feel hot? When a stove burner has a high tem ...
New light on our Sun`s fate - Space Telescope Science Institute
... of most stars. Shortly after a star forms, its central core reaches a temperature of tens of millions of degrees, hot enough to fuse hydrogen into helium and energy. During this phase of nuclear “burning,” a star’s appearance remains quite stable, with little change in its luminosity, size, and temp ...
... of most stars. Shortly after a star forms, its central core reaches a temperature of tens of millions of degrees, hot enough to fuse hydrogen into helium and energy. During this phase of nuclear “burning,” a star’s appearance remains quite stable, with little change in its luminosity, size, and temp ...
Life Cycle of Stars
... Hubble Space Telescope ACS/HRC – NASA, ESA, N.Evans (Harvard-Smithsonian CfA), and H.Bond (S TScl) ...
... Hubble Space Telescope ACS/HRC – NASA, ESA, N.Evans (Harvard-Smithsonian CfA), and H.Bond (S TScl) ...
Syllabus
... Low Mass stellar Life Stages Low Mass Stellar Death High Mass stellar Life Stages High Mass Stellar Death Binary System Characteristics Binary / Single System differences ...
... Low Mass stellar Life Stages Low Mass Stellar Death High Mass stellar Life Stages High Mass Stellar Death Binary System Characteristics Binary / Single System differences ...
Reference Table Review - Mr. G`s Earth Science
... 21.Sedimentary rock that is subjected to heat and pressure changes into what type of rock? 22.How does igneous rock become sedimentary rock? 23.Particle sizes from 0.2cm to 6.4cm are classified as what type of sediment? 24.What are the largest sized particles that can be moved by a river traveling ...
... 21.Sedimentary rock that is subjected to heat and pressure changes into what type of rock? 22.How does igneous rock become sedimentary rock? 23.Particle sizes from 0.2cm to 6.4cm are classified as what type of sediment? 24.What are the largest sized particles that can be moved by a river traveling ...
Mark Rubin
... • As a result of the rapid pollution within high-density regions due to the first SN/pair instability SN, local metallicity is quickly boosted above the critical metallicity for the transition. • For this reason, pop III stars dominate only during the very first stages of structure formation, with a ...
... • As a result of the rapid pollution within high-density regions due to the first SN/pair instability SN, local metallicity is quickly boosted above the critical metallicity for the transition. • For this reason, pop III stars dominate only during the very first stages of structure formation, with a ...
Parameters of a Strömgren Sphere Let`s assume that we have a
... singlet decays from 2 1 P to 1 1 S are no problem, but 2 1 S to 1 1 S is forbidden; these atoms can only decay by creating a temporary state somewhere between 2 1 S and 1 1 S and emitting 2 photons (A = 51 sec−1 ). When this occurs, 56% of the time, one of the photons will have an energy greater tha ...
... singlet decays from 2 1 P to 1 1 S are no problem, but 2 1 S to 1 1 S is forbidden; these atoms can only decay by creating a temporary state somewhere between 2 1 S and 1 1 S and emitting 2 photons (A = 51 sec−1 ). When this occurs, 56% of the time, one of the photons will have an energy greater tha ...
Mock Exam 2013 Paper 2
... excited state of a hydrogen atom is called the Paschen series. Which of the following gives the highest frequency f of the spectral lines in the Paschen series? ...
... excited state of a hydrogen atom is called the Paschen series. Which of the following gives the highest frequency f of the spectral lines in the Paschen series? ...
H R Diagram Online Activity
... 2. “The position of each dot on the diagram tells us two things about each star: its _____________________ (or absolute magnitude) and its _____________________________” 3. “The vertical axis represents the star’s ________________________ or absolute magnitude. Luminosity is technically the amount o ...
... 2. “The position of each dot on the diagram tells us two things about each star: its _____________________ (or absolute magnitude) and its _____________________________” 3. “The vertical axis represents the star’s ________________________ or absolute magnitude. Luminosity is technically the amount o ...
Lecture 11: Stars, HR diagram.
... There is a very tight relationship between luminosity and temperature We see that the Sun is in this sequence... Then there is something in common between the Sun and the rest of the stars in the main sequence.... They are all burning H into He in their cores More luminous = hotter = more massive! L ...
... There is a very tight relationship between luminosity and temperature We see that the Sun is in this sequence... Then there is something in common between the Sun and the rest of the stars in the main sequence.... They are all burning H into He in their cores More luminous = hotter = more massive! L ...
Ay 112 Midterm review
... The Saha equation can be used to calculate the ionization state of atoms in local thermodynamic equilibrium. This equation gives the abundaces of e.g., H I and H II in terms of ne, the temperature ...
... The Saha equation can be used to calculate the ionization state of atoms in local thermodynamic equilibrium. This equation gives the abundaces of e.g., H I and H II in terms of ne, the temperature ...
chapter16StarBirth
... Mass of a Star-Forming Cloud • A typical molecular cloud (T~ 30 K, n ~ 300 particles/cm3) must contain at least a few hundred solar masses for gravity to overcome pressure • Emission lines from molecules in a cloud can prevent a pressure buildup by converting thermal energy into infrared and radio ...
... Mass of a Star-Forming Cloud • A typical molecular cloud (T~ 30 K, n ~ 300 particles/cm3) must contain at least a few hundred solar masses for gravity to overcome pressure • Emission lines from molecules in a cloud can prevent a pressure buildup by converting thermal energy into infrared and radio ...
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.