here - Atomki
... On the other hand, we can estimate the free-fall timescale, tff, by ignoring the pressure term in the eqn. of motion. We then can write: d2r/dt2 ≈ R/tff2 → tff ≈ √(R/g) (≈ 1/2√(G<ρ>) = tdyn ) Examples for tff/tdyn: 30 min for the sun, 18 days for red giant (100R⊙), 4.5 s for white dwarfs (R⊙/50) << ...
... On the other hand, we can estimate the free-fall timescale, tff, by ignoring the pressure term in the eqn. of motion. We then can write: d2r/dt2 ≈ R/tff2 → tff ≈ √(R/g) (≈ 1/2√(G<ρ>) = tdyn ) Examples for tff/tdyn: 30 min for the sun, 18 days for red giant (100R⊙), 4.5 s for white dwarfs (R⊙/50) << ...
Chapter 10 Hertzsprung-Russel Diagrams and Distance to Stars
... only its apparent brightness. As we’ve already said, a bright star that’s very far away would appear much fainter than a dim star that’s much closer. To overcome this problem, scientists began to look at stars that were found in clusters. In general, it’s safe to assume that all the stars in a clust ...
... only its apparent brightness. As we’ve already said, a bright star that’s very far away would appear much fainter than a dim star that’s much closer. To overcome this problem, scientists began to look at stars that were found in clusters. In general, it’s safe to assume that all the stars in a clust ...
4550-15Lecture33
... helium. The relationship results from the rate of hydrogen burning: large stars have hot, dense interiors and burn hydrogen much faster than smaller stars. Consequently there is an inverse relationship between the main sequence lifetime of a star and mass. The most massive stars, up to ~100 solar ma ...
... helium. The relationship results from the rate of hydrogen burning: large stars have hot, dense interiors and burn hydrogen much faster than smaller stars. Consequently there is an inverse relationship between the main sequence lifetime of a star and mass. The most massive stars, up to ~100 solar ma ...
27.1: Characteristics of Stars
... Surface Temperature of a Star White stars have a surface temperatures ranging from 7,500 – 10,000°K White stars are NOT the same thing as white dwarfs! White dwarfs happen at the end of a star’s life, and they can be as hot as 100,000 °K! ...
... Surface Temperature of a Star White stars have a surface temperatures ranging from 7,500 – 10,000°K White stars are NOT the same thing as white dwarfs! White dwarfs happen at the end of a star’s life, and they can be as hot as 100,000 °K! ...
Lecture 39
... helium. The relationship results from the rate of hydrogen burning: large stars have hot, dense interiors and burn hydrogen much faster than smaller stars. Consequently there is an inverse relationship between the main sequence lifetime of a star and mass. The most massive stars, up to ~100 solar ma ...
... helium. The relationship results from the rate of hydrogen burning: large stars have hot, dense interiors and burn hydrogen much faster than smaller stars. Consequently there is an inverse relationship between the main sequence lifetime of a star and mass. The most massive stars, up to ~100 solar ma ...
giant molecular clouds
... Star formation collapse of the cores of giant molecular clouds: Dark, cold, dense clouds obscuring the light of stars behind them. ...
... Star formation collapse of the cores of giant molecular clouds: Dark, cold, dense clouds obscuring the light of stars behind them. ...
charts_set_7
... Hot, massive stars produce huge amounts of these. Such short-lived stars spend all their lives in the stellar nursery of their birth, so emission nebulae mark sites of ongoing star formation. Many stars of lower mass are forming too, but emit few UV photons. ...
... Hot, massive stars produce huge amounts of these. Such short-lived stars spend all their lives in the stellar nursery of their birth, so emission nebulae mark sites of ongoing star formation. Many stars of lower mass are forming too, but emit few UV photons. ...
The life and times of stars
... The cause of the lines is not understood until Kirchoff and Bunsen explain them in 1860 ...
... The cause of the lines is not understood until Kirchoff and Bunsen explain them in 1860 ...
slides - Indico
... Require large samples of, in particular, r-process-enhanced, metal-poor stars in order to place constraints on the nature of the r-process, its site(s), examination of possible variation in abundance patterns from star to star, and of course… ...
... Require large samples of, in particular, r-process-enhanced, metal-poor stars in order to place constraints on the nature of the r-process, its site(s), examination of possible variation in abundance patterns from star to star, and of course… ...
Evolution of a Protostar
... A protostar looks starlike after the surrounding gas is blown away, but its thermal energy comes from gravitational contraction, not fusion. ...
... A protostar looks starlike after the surrounding gas is blown away, but its thermal energy comes from gravitational contraction, not fusion. ...
Announcements Evolution of High-Mass Stars: Red Supergiants
... • Parallax only works for nearby stars (within about 1000 light years) • For more distant stars, we use Standard Candles Car Headlights are standard candles: We use them to determine the car’s distance ...
... • Parallax only works for nearby stars (within about 1000 light years) • For more distant stars, we use Standard Candles Car Headlights are standard candles: We use them to determine the car’s distance ...
Phase Analysis of RV Tauri and Semi-regular Variables Abstract
... Z UMa is classified as a Semi-Regular variable star and has a period of 195.5 days. The graph below on the left is an example of a failed model-fit attempt and also illustrates Z UMa’s semi-regular light curve. The graph on the right shows the model-fit light curve used for the spectral date of 2453 ...
... Z UMa is classified as a Semi-Regular variable star and has a period of 195.5 days. The graph below on the left is an example of a failed model-fit attempt and also illustrates Z UMa’s semi-regular light curve. The graph on the right shows the model-fit light curve used for the spectral date of 2453 ...
Slides from Lecture06
... • A plot of light intensity versus wavelength always has the same general appearance (blackbody function): – Very little light at very short wavelengths – Very little light at very long wavelengths – Intensity of light peaks at some intermediate wavelength ...
... • A plot of light intensity versus wavelength always has the same general appearance (blackbody function): – Very little light at very short wavelengths – Very little light at very long wavelengths – Intensity of light peaks at some intermediate wavelength ...
November 2005 - Otterbein University
... • Too distant to resolve the individual stars • Can be viewed indirectly by observing the back-and-forth Doppler shifts of their spectral lines ...
... • Too distant to resolve the individual stars • Can be viewed indirectly by observing the back-and-forth Doppler shifts of their spectral lines ...
Chapter10 (with interactive links)
... The spectra of stars were first classified during the late 1800s. Stars with the strongest hydrogen lines were labelled “A,” stars with somewhat weaker hydrogen lines were labelled “B stars,” and … ...
... The spectra of stars were first classified during the late 1800s. Stars with the strongest hydrogen lines were labelled “A,” stars with somewhat weaker hydrogen lines were labelled “B stars,” and … ...
Stars, Galaxies & Universe
... • What type of telescope collect electromagnetic waves other than light? • radio telescope • How long ago did the Big Bang occur? • 10-15 billion years ago ...
... • What type of telescope collect electromagnetic waves other than light? • radio telescope • How long ago did the Big Bang occur? • 10-15 billion years ago ...
Kinds of Stars
... Example is a DIFFUSE NEBULA Brightest known is in constellation ORION. 2. Nebulae clouds contact each other and glow. These are called PROTOSTARS. – Dark Nebulae- Away from stars. “HorseHead” ...
... Example is a DIFFUSE NEBULA Brightest known is in constellation ORION. 2. Nebulae clouds contact each other and glow. These are called PROTOSTARS. – Dark Nebulae- Away from stars. “HorseHead” ...
Powerpoint for today
... The proton and electron each have “spin”. A result from quantum mechanics: if both spinning the same way, atom's energy is slightly higher. Eventually will make transition to state of opposite spins. Energy difference is small -> radio photon emitted, wavelength 21-cm. ...
... The proton and electron each have “spin”. A result from quantum mechanics: if both spinning the same way, atom's energy is slightly higher. Eventually will make transition to state of opposite spins. Energy difference is small -> radio photon emitted, wavelength 21-cm. ...
Hertzsprung-Russell Diagrams and Distance to Stars
... only its apparent brightness. As we’ve already said, a bright star that’s very far away would appear much fainter than a dim star that’s much closer. To overcome this problem, scientists began to look at stars that were found in clusters. In general, it’s safe to assume that all the stars in a clust ...
... only its apparent brightness. As we’ve already said, a bright star that’s very far away would appear much fainter than a dim star that’s much closer. To overcome this problem, scientists began to look at stars that were found in clusters. In general, it’s safe to assume that all the stars in a clust ...
Slide 1 - Personal.psu.edu
... Star formation happens when part of a dust cloud begins to contract under its own gravitational force; as it collapses, the center becomes hotter and hotter until nuclear fusion begins in the core. ...
... Star formation happens when part of a dust cloud begins to contract under its own gravitational force; as it collapses, the center becomes hotter and hotter until nuclear fusion begins in the core. ...
1. If a star`s temperature is doubled but radius is kept constant, by
... 1. If a star’s temperature is doubled but radius is kept constant, by how much does its luminosity go up by? 1a. Goes up by a factor of 24 = 16. 2. If a star’s temperature is increased by a factor of three, four, five and six, but in every case its radius is kept constant, what happens to its lumino ...
... 1. If a star’s temperature is doubled but radius is kept constant, by how much does its luminosity go up by? 1a. Goes up by a factor of 24 = 16. 2. If a star’s temperature is increased by a factor of three, four, five and six, but in every case its radius is kept constant, what happens to its lumino ...
White Dwarfs
... in their core become white dwarfs. • Hot exposed core of an evolved low mass star. • Supported by electron degeneracy pressure. This is the tendency of atoms to resist compression. • The more massive a white dwarf, the smaller it is. A solar mass white dwarf is about the size of the Earth. • As ...
... in their core become white dwarfs. • Hot exposed core of an evolved low mass star. • Supported by electron degeneracy pressure. This is the tendency of atoms to resist compression. • The more massive a white dwarf, the smaller it is. A solar mass white dwarf is about the size of the Earth. • As ...
FINAL EXAM Name: ASTRONOMY II - 79202 Spring 1995
... 15. Star clusters generally show a clear main sequence line which cuts off abruptly for effective temperatures greater than some value. This cutoff temperature indicates the cluster’s A. B. C. D. E. ...
... 15. Star clusters generally show a clear main sequence line which cuts off abruptly for effective temperatures greater than some value. This cutoff temperature indicates the cluster’s A. B. C. D. E. ...
Stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Light from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. A8, A9, F0, F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such class D for white dwarfs and class C for carbon stars.In the MK system a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ stars for hypergiants, class I stars for supergiants, class II for bright giants, class III for regular giants, class IV for sub-giants, class V for main-sequence stars, class sd for sub-dwarfs, and class D for white dwarfs. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800K.