giants1
... Comparison of the stellar parameters with theoretical isochrones (Girardi et al. 2000) using a modified version of the Bayesian estimation of Jorgenson and Lindegren (2005) algorithm. The total probability distribution function of belonging to M,t space is computed from the Mv, Teff, [Fe/H] probabil ...
... Comparison of the stellar parameters with theoretical isochrones (Girardi et al. 2000) using a modified version of the Bayesian estimation of Jorgenson and Lindegren (2005) algorithm. The total probability distribution function of belonging to M,t space is computed from the Mv, Teff, [Fe/H] probabil ...
The Evolution of Elements
... destroyed as soon as they are formed as they encounter electrons, but during their brief existence they are the electron’s counterpart: they have very little mass (mass number = 0) but hold a positive charge (same atomic number as hydrogen). Stars of different sizes go on to produce elements. The gr ...
... destroyed as soon as they are formed as they encounter electrons, but during their brief existence they are the electron’s counterpart: they have very little mass (mass number = 0) but hold a positive charge (same atomic number as hydrogen). Stars of different sizes go on to produce elements. The gr ...
nuclear fusion atoms
... 4. Ninety-five percent of matter in the universe is found in ___________________ . 5. By looking deep into space, we can see back in time about __________________ billion years. 6. Many cosmologists say the ________ _________ Theory helps explain why the universe has universal forces and continues t ...
... 4. Ninety-five percent of matter in the universe is found in ___________________ . 5. By looking deep into space, we can see back in time about __________________ billion years. 6. Many cosmologists say the ________ _________ Theory helps explain why the universe has universal forces and continues t ...
COMPONENTS OF THE UNIVERSE
... energy; others emit less energy. Stars may be young, middle-aged, old, or dying. They may be composed primarily of hydrogen, or they may contain mostly helium and heavier elements. Some are very bright; others are dimmer. Their colors range from blue and white to yellow and red. In the early 1900s, ...
... energy; others emit less energy. Stars may be young, middle-aged, old, or dying. They may be composed primarily of hydrogen, or they may contain mostly helium and heavier elements. Some are very bright; others are dimmer. Their colors range from blue and white to yellow and red. In the early 1900s, ...
WIMPs versus MACHOS
... Dark Matter governs the majestic rotation of galaxies seeds the evolution of cosmic structures determines the fate of the Universe Understanding the nature and distribution of Dark Matter is one of the most pressing open questions in the physical sciences today ...
... Dark Matter governs the majestic rotation of galaxies seeds the evolution of cosmic structures determines the fate of the Universe Understanding the nature and distribution of Dark Matter is one of the most pressing open questions in the physical sciences today ...
Vibrational instability of Population III very massive mainsequence
... Very massive stars are thought to be formed in the early Universe because of a lack of cooling process by heavy elements, and might have been responsible for the later evolution of the Universe. We had an interest in the vibrational stability of their evolution and have carried out a linear non-adia ...
... Very massive stars are thought to be formed in the early Universe because of a lack of cooling process by heavy elements, and might have been responsible for the later evolution of the Universe. We had an interest in the vibrational stability of their evolution and have carried out a linear non-adia ...
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
... (c) Assuming that the moment of inertia is that of a uniform sphere when the collapse begins, and that the moment inertia is that of a uniform disk when the collapse ends, determine the rotational velocity at 100 AU when the collapse stops. (d) After the collapse has stopped, calculate the time requ ...
... (c) Assuming that the moment of inertia is that of a uniform sphere when the collapse begins, and that the moment inertia is that of a uniform disk when the collapse ends, determine the rotational velocity at 100 AU when the collapse stops. (d) After the collapse has stopped, calculate the time requ ...
Int. Sci. 9 - Universe Powerpoint
... partially vaporize when they pass near the sun • Meteoroids – pieces of rock, usually less than a few hundred meters in size ...
... partially vaporize when they pass near the sun • Meteoroids – pieces of rock, usually less than a few hundred meters in size ...
Review (PPT) - Uplift Summit Intl
... ▪ Star collapses when most of the hydrogen nuclei have fused into helium. ▪ Gravity now outweighs the radiation pressure and the star shrinks in size and heats up. ▪ The hydrogen in the layer surrounding the shrunken core is now able to fuse, raising the temperature of the outer layers which makes t ...
... ▪ Star collapses when most of the hydrogen nuclei have fused into helium. ▪ Gravity now outweighs the radiation pressure and the star shrinks in size and heats up. ▪ The hydrogen in the layer surrounding the shrunken core is now able to fuse, raising the temperature of the outer layers which makes t ...
Supernovae
... • Neutrino detection consistent with that expected from SN in LMC in Feb 1987. This was probably type II SN because originator was massive B star (20 solar masses)… although also individual. • Neutrinos are rarely absorbed so energy changed little over many x 10 9 years (except for loss due to expa ...
... • Neutrino detection consistent with that expected from SN in LMC in Feb 1987. This was probably type II SN because originator was massive B star (20 solar masses)… although also individual. • Neutrinos are rarely absorbed so energy changed little over many x 10 9 years (except for loss due to expa ...
Stars, Galaxies, and the Universe
... this dust and gas to “clump” together. As these “clumps” gather more atoms (mass), their gravitational attraction to other atoms increases, pulling more atoms into the “clump.” ...
... this dust and gas to “clump” together. As these “clumps” gather more atoms (mass), their gravitational attraction to other atoms increases, pulling more atoms into the “clump.” ...
–1– 1. Stellar Evolution For Massive Stars 1.1. The Importance of
... burned material from the central regions of the star as well as angular momentum are transported to the stellar surface region by rotational mixing. Rotation can enhance mass loss in low Z stars in two ways. The first is by reducing the effective gravity of the star as compared to one rotating slowl ...
... burned material from the central regions of the star as well as angular momentum are transported to the stellar surface region by rotational mixing. Rotation can enhance mass loss in low Z stars in two ways. The first is by reducing the effective gravity of the star as compared to one rotating slowl ...
Observational Overview
... DISK – thin compared to the diameter, thickness = 0.3 kpc and diameter = 25 kpc. Contains all raw material for making stars (huge clouds of molecular hydrogen and dust (tiny particles made of carbon and silicate)) and all the young stars, including Sun which is 8 kpc from centre. BULGE – contains o ...
... DISK – thin compared to the diameter, thickness = 0.3 kpc and diameter = 25 kpc. Contains all raw material for making stars (huge clouds of molecular hydrogen and dust (tiny particles made of carbon and silicate)) and all the young stars, including Sun which is 8 kpc from centre. BULGE – contains o ...
script
... Pollution hypothesis: During planet formation the giant planets migrate in and collide with the star. They have a higher content of metals and thus pollute the outer layers of the stellar atmosphere. Because the convection zone for main sequence stars is not as deep, the „polluted“ layers survive f ...
... Pollution hypothesis: During planet formation the giant planets migrate in and collide with the star. They have a higher content of metals and thus pollute the outer layers of the stellar atmosphere. Because the convection zone for main sequence stars is not as deep, the „polluted“ layers survive f ...
Chapter 11. Stellar Brightness, Magnitudes, the Distance
... 50 solar masses or perhaps a little larger. M-type stars have masses down below 0.1 solar masses. The smallest mass object that can start its nuclear fusion of Hydrogen is thought to be about 0.07 solar masses, so this represents the smallest stars we see. These are of class M. We do find cooler obj ...
... 50 solar masses or perhaps a little larger. M-type stars have masses down below 0.1 solar masses. The smallest mass object that can start its nuclear fusion of Hydrogen is thought to be about 0.07 solar masses, so this represents the smallest stars we see. These are of class M. We do find cooler obj ...
Learning Targets
... 2 = It’s familiar, but I can’t tell you what it is. 3 = I know what it is, but can’t put it into words. 4 = I know this well enough to teach it to someone else. LEARNING TARGET ...
... 2 = It’s familiar, but I can’t tell you what it is. 3 = I know what it is, but can’t put it into words. 4 = I know this well enough to teach it to someone else. LEARNING TARGET ...
RADIUS (6371 KM) - Department of Earth and Planetary Sciences
... pulls matter from regions of lower density onto regions of higher density. Frame three captures the era of the first stars, 200 million years after the Big Bang. Gas has condensed and heated up to temperatures high enough to initiate nuclear fusion, the engine of the stars. Frame four shows more sta ...
... pulls matter from regions of lower density onto regions of higher density. Frame three captures the era of the first stars, 200 million years after the Big Bang. Gas has condensed and heated up to temperatures high enough to initiate nuclear fusion, the engine of the stars. Frame four shows more sta ...
Red Supergiants as the Progenitors of Type IIP Supernova
... While for a 2D model with explosion energy around 1.8× 1051 erg the Si and Ni containing structures still move with nearly 4000 km s-1 (oxygen has velocities up to even 5000 km s-1) at 300 s, a strong deceleration occurs when the metal clumps enter the relatively dense He-shell that forms after the ...
... While for a 2D model with explosion energy around 1.8× 1051 erg the Si and Ni containing structures still move with nearly 4000 km s-1 (oxygen has velocities up to even 5000 km s-1) at 300 s, a strong deceleration occurs when the metal clumps enter the relatively dense He-shell that forms after the ...
Planets around Stars Beyond the Main Sequence (Evolved Stars)
... Pollution hypothesis: During planet formation the giant planets migrate in and collide with the star. They have a higher content of metals and thus pollute the outer layers of the stellar atmosphere. Because the convection zone for main sequence stars is not as deep, the „polluted“ layers survive f ...
... Pollution hypothesis: During planet formation the giant planets migrate in and collide with the star. They have a higher content of metals and thus pollute the outer layers of the stellar atmosphere. Because the convection zone for main sequence stars is not as deep, the „polluted“ layers survive f ...
Origins of the Universe
... us the more it is red shifted • The only explanation for that is if everything is moving away from us. • This means the universe is expanding ...
... us the more it is red shifted • The only explanation for that is if everything is moving away from us. • This means the universe is expanding ...
– 1 – 1. A Gas
... that a 10% increase in T leads to a factor of 45 increase in the nuclear energy generation rate ! Ignoring gravitational contraction and other non-nuclear energy sources, L(r) must increase outward, until the r beyond which the gas is too cool for nuclear reactions to occur is reached, beyond which ...
... that a 10% increase in T leads to a factor of 45 increase in the nuclear energy generation rate ! Ignoring gravitational contraction and other non-nuclear energy sources, L(r) must increase outward, until the r beyond which the gas is too cool for nuclear reactions to occur is reached, beyond which ...
m 1
... 1. Use stars < 100pc to calibrate MV for spectral classes 2. For unknown star: a) use CCD to measure mV b) use spectrograph to find spectral class c) use calibration from (1) to get MV d) use distance modulus to calculate d ...
... 1. Use stars < 100pc to calibrate MV for spectral classes 2. For unknown star: a) use CCD to measure mV b) use spectrograph to find spectral class c) use calibration from (1) to get MV d) use distance modulus to calculate d ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.