4. Star Formation
... – at densities of 1011 cm−3 and at a radius of 1014 cm the gas becomes optically thick for dust radiation at even 300µ m. Hence, energy is trapped and the temperature rises; increasing temperature increases opacity further; collapse turns adiabatic – The high thermal pressure resists gravity and end ...
... – at densities of 1011 cm−3 and at a radius of 1014 cm the gas becomes optically thick for dust radiation at even 300µ m. Hence, energy is trapped and the temperature rises; increasing temperature increases opacity further; collapse turns adiabatic – The high thermal pressure resists gravity and end ...
The Main Sequence - University of Arizona
... CNO vs. PP Chain • Equate CNO and PP energy production to find where each dominates • T ~ 1.7x107(XH/50XCN)1/12.1 • Crossover point occurs at ~ 1.1 M for Pop I • At z=0 must reach He burning T and produce CNO catalysts • (PP)~X2H0(T/T0)4.6 ; (CNO) ~XHXCNOfN0(T/T0)16.7 • PP and CNO have to pr ...
... CNO vs. PP Chain • Equate CNO and PP energy production to find where each dominates • T ~ 1.7x107(XH/50XCN)1/12.1 • Crossover point occurs at ~ 1.1 M for Pop I • At z=0 must reach He burning T and produce CNO catalysts • (PP)~X2H0(T/T0)4.6 ; (CNO) ~XHXCNOfN0(T/T0)16.7 • PP and CNO have to pr ...
From studying our solar system to searching for worlds beyond and
... Vasily Belokurov enters his office every morning hoping to understand how the universe — and particularly the Milky Way — formed. “I am a survey scientist and a galactic archaeologist,” Belokurov says. “I trawl through the data of massive sky surveys for clues to the formation and evolution of our g ...
... Vasily Belokurov enters his office every morning hoping to understand how the universe — and particularly the Milky Way — formed. “I am a survey scientist and a galactic archaeologist,” Belokurov says. “I trawl through the data of massive sky surveys for clues to the formation and evolution of our g ...
Presentation - Harvard-Smithsonian Center for Astrophysics
... Suggests that high T plasma, 6.8 K (dex) is anchored close to the stellar surface reminiscent of low-lying coronal loops… ...
... Suggests that high T plasma, 6.8 K (dex) is anchored close to the stellar surface reminiscent of low-lying coronal loops… ...
Stellar Temperatures
... blackbodies, with stellar absorption lines on top. There is a great variety of stellar absorption lines; the strength of any individual line is determine by the star’s • Temperature (most important) • Gravity • Abundance Historically, stellar spectral types have been classified using letters; the ...
... blackbodies, with stellar absorption lines on top. There is a great variety of stellar absorption lines; the strength of any individual line is determine by the star’s • Temperature (most important) • Gravity • Abundance Historically, stellar spectral types have been classified using letters; the ...
Stellar Populations For many modern applications, one is not
... The above analytic solutions are only useful for guidance. To compare with observations, predictions must be made in specific bandpasses, or for specific absorption lines. This requires numerical calculations which include 1) sets of stellar isochrones, detailing the precise number of stars at any p ...
... The above analytic solutions are only useful for guidance. To compare with observations, predictions must be made in specific bandpasses, or for specific absorption lines. This requires numerical calculations which include 1) sets of stellar isochrones, detailing the precise number of stars at any p ...
The Triple-Ring Nebula: Fingerprint of a Binary Merger
... least 1,000 times the radius of the Sun4 . In addition, the composition of the star that exploded was very unusual; most importantly, the outer layers of the star had an abundance of helium (as a fraction of the total composition) that was about a factor of 2 larger than the expected abundance, as i ...
... least 1,000 times the radius of the Sun4 . In addition, the composition of the star that exploded was very unusual; most importantly, the outer layers of the star had an abundance of helium (as a fraction of the total composition) that was about a factor of 2 larger than the expected abundance, as i ...
smallest exoplanet - Forsyth Astronomical Society
... Astronomers plan to observe a rare cosmic cradle for the universe's largest stars, - baby bruisers that grow up to have 50 times the Sun's mass. The Carina cloud is also unusual in its rapid pace of collapse and the amount of dust and gas, an amount so large it eclipsed the large stars that had alre ...
... Astronomers plan to observe a rare cosmic cradle for the universe's largest stars, - baby bruisers that grow up to have 50 times the Sun's mass. The Carina cloud is also unusual in its rapid pace of collapse and the amount of dust and gas, an amount so large it eclipsed the large stars that had alre ...
Stellar Remnants White Dwarfs, Neutron Stars & Black Holes
... solids, liquids or gases. • They often have very strong magnetic fields and very rapid spin rates. ...
... solids, liquids or gases. • They often have very strong magnetic fields and very rapid spin rates. ...
30.4 Gravitational collapse & early protostellar evolution I (HB)
... gaining energy from the gravitational contraction. - Different evolution for low- and high-mass pre-main sequence stars: - Low-mass: Shrinking releases gravitational energy while surface temperature stays approximately constant. Since L = 4πR2sBTeff4 R*2, the luminosity decreases and falls below L ...
... gaining energy from the gravitational contraction. - Different evolution for low- and high-mass pre-main sequence stars: - Low-mass: Shrinking releases gravitational energy while surface temperature stays approximately constant. Since L = 4πR2sBTeff4 R*2, the luminosity decreases and falls below L ...
River - Phillips Indian Educators
... conscientize and decide how an Indigenous worldview/philosophy/CLAH not only had STEM and this “Milky Way-Big River-Astroscience”…but very early on… and even much more! The non-Indigenous view has recently begun to include some of our views of Sky-Earth relatedness under a sub-discipline called ARCH ...
... conscientize and decide how an Indigenous worldview/philosophy/CLAH not only had STEM and this “Milky Way-Big River-Astroscience”…but very early on… and even much more! The non-Indigenous view has recently begun to include some of our views of Sky-Earth relatedness under a sub-discipline called ARCH ...
The ISM and Stellar Birth
... • Near the Sun, Extinction amounts to 2 magnitudes per 1000 parsecs. That is, a star 1000pc from Earth will look about 2 magnitudes fainter than if space were empty completely • Dust thought to come from stellar ‘winds’, blowing out molecules of hydrogen, carbon, oxygen and other elements which coo ...
... • Near the Sun, Extinction amounts to 2 magnitudes per 1000 parsecs. That is, a star 1000pc from Earth will look about 2 magnitudes fainter than if space were empty completely • Dust thought to come from stellar ‘winds’, blowing out molecules of hydrogen, carbon, oxygen and other elements which coo ...
STANDARD 4a
... nebula, a cloud of dust and gas • Gravity pulls the dust and gas together to form a star at the center • When the star becomes dense enough, nuclear fusion begins and the star lights up ...
... nebula, a cloud of dust and gas • Gravity pulls the dust and gas together to form a star at the center • When the star becomes dense enough, nuclear fusion begins and the star lights up ...
Nucleosynthesis in asymptotic giant branch stars
... the so called hot bottom burning (HBB). This is an envelope convective burning, where the convective envelope reaches the top of the H-burning shell (see Fig. 2). But such a process does not occur unless the initial stellar mass is above 4 M¯ in case of initial solar-like metallicity, but it could a ...
... the so called hot bottom burning (HBB). This is an envelope convective burning, where the convective envelope reaches the top of the H-burning shell (see Fig. 2). But such a process does not occur unless the initial stellar mass is above 4 M¯ in case of initial solar-like metallicity, but it could a ...
The American Flag - US Citizenship Teachers
... At first one star and one stripe was added for each new state. This is the flag the flew over Fort McHenry during the War of 1812. It inspired the national anthem, “The Star Spangled Banner.” ...
... At first one star and one stripe was added for each new state. This is the flag the flew over Fort McHenry during the War of 1812. It inspired the national anthem, “The Star Spangled Banner.” ...
ppt - SLAC
... A W-R star is “A hot (25,000 to 50,000 K), massive (more than 25 solar masses), luminous star in an advanced stage of evolution, which is losing mass in the form a powerful stellar wind. Wolf-Rayets are believed to be O stars that have lost their hydrogen envelopes, leaving their helium cores expose ...
... A W-R star is “A hot (25,000 to 50,000 K), massive (more than 25 solar masses), luminous star in an advanced stage of evolution, which is losing mass in the form a powerful stellar wind. Wolf-Rayets are believed to be O stars that have lost their hydrogen envelopes, leaving their helium cores expose ...
network of amateur astronomers (CBA) to gather data on CV`s.
... e. Measurements made exactly like Tim described except no comp star is needed because it is a differential measurement. However the components of doubles may be of quite different colors and color transformation becomes an issue. With a single filter (V) no color info for most doubles to transform m ...
... e. Measurements made exactly like Tim described except no comp star is needed because it is a differential measurement. However the components of doubles may be of quite different colors and color transformation becomes an issue. With a single filter (V) no color info for most doubles to transform m ...
Document
... We have a unique data set that offers unprecedented temporal coverage of >1600 stars down to 19th magnitude, yielding a detection of variability in about 8% of the field stars. Have measured eclipsing binary periods down to tenths or hundredths of a second. Variation in orbital parameters gives info ...
... We have a unique data set that offers unprecedented temporal coverage of >1600 stars down to 19th magnitude, yielding a detection of variability in about 8% of the field stars. Have measured eclipsing binary periods down to tenths or hundredths of a second. Variation in orbital parameters gives info ...
stellar interiors instructor notes
... surface. Yet, one can construct abstract mathematical models of massive spheres of hot gas in equilibrium and deduce their properties from what is known about the physics of matter. Would it come as a surprise to scientists on such a planet if the constant canopy of surrounding clouds one day parted ...
... surface. Yet, one can construct abstract mathematical models of massive spheres of hot gas in equilibrium and deduce their properties from what is known about the physics of matter. Would it come as a surprise to scientists on such a planet if the constant canopy of surrounding clouds one day parted ...
Gravitational mass defect
... phenomenon does not find its thus far explanation and are not known those energy sources, which can lead to so immense an explosion. The process of the collision of neutron stars examined can be precisely such source. In its essence this explosion - this is the explosion of the nuclear charge of ver ...
... phenomenon does not find its thus far explanation and are not known those energy sources, which can lead to so immense an explosion. The process of the collision of neutron stars examined can be precisely such source. In its essence this explosion - this is the explosion of the nuclear charge of ver ...
AST 301 Introduction to Astronomy - University of Texas Astronomy
... made of) were made in the big bang. Many of the helium atoms in the Universe were also made in the big bang. The other atoms were made inside of stars or during explosions of stars. When the Sun becomes a red giant, carbon and maybe oxygen will be made in its core. But the core will be the left-over ...
... made of) were made in the big bang. Many of the helium atoms in the Universe were also made in the big bang. The other atoms were made inside of stars or during explosions of stars. When the Sun becomes a red giant, carbon and maybe oxygen will be made in its core. But the core will be the left-over ...
March 2011
... almost directly overhead, see the chart on page 6. The brilliant bright yellow / white star Capella is the sixth brightest star in the night sky at a magnitude of +0.08. At the beginning of March Capella is directly overhead at 18:30. By the end of the month it is directly overhead by 17:00. After a ...
... almost directly overhead, see the chart on page 6. The brilliant bright yellow / white star Capella is the sixth brightest star in the night sky at a magnitude of +0.08. At the beginning of March Capella is directly overhead at 18:30. By the end of the month it is directly overhead by 17:00. After a ...
B2 MOCK EXAM LISTENING COMPREHENSION I. Listen to a talk
... there are probably twice as many herons breeding in Britain today than in the late 1960s. ________________ This means herons can breed and survive in areas which were previously unavailable because they were either too cold or ruined by poisonous substances in the water. ...
... there are probably twice as many herons breeding in Britain today than in the late 1960s. ________________ This means herons can breed and survive in areas which were previously unavailable because they were either too cold or ruined by poisonous substances in the water. ...
How do we know what stars are
... Life Cycle of Stars Video https://www.youtube.com/watch?v=mzE7VZMT1z8 Age of a star is determined by the emission spectrum and the percentage of heavier elements. A star begins its life composed of _______________. Fusion creates ____________ in the core which increases as the star ages. When helium ...
... Life Cycle of Stars Video https://www.youtube.com/watch?v=mzE7VZMT1z8 Age of a star is determined by the emission spectrum and the percentage of heavier elements. A star begins its life composed of _______________. Fusion creates ____________ in the core which increases as the star ages. When helium ...
ASTR 1101-001 Spring 2008 - Louisiana State University
... fusion of He into C & O and into the “AGB” phase – But gravity is strong enough (because of the star’s larger mass) for succeeding stages of nuclear “burning” to be triggered – When the star exhausts a given variety of nuclear fuel in its core, the “ash” of the previous fusion stage is ignited – The ...
... fusion of He into C & O and into the “AGB” phase – But gravity is strong enough (because of the star’s larger mass) for succeeding stages of nuclear “burning” to be triggered – When the star exhausts a given variety of nuclear fuel in its core, the “ash” of the previous fusion stage is ignited – The ...
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.