Oscillating White Dwarf Stars Background on White Dwarfs
... temperatures of 100.000.000 K. 8Be is unstable and decays back into He in 2.6 × 10–16 secs, but in the stellar interior a small equilibrium of 8Be exists. The 8Be ground state has almost exactly the energy of two alpha particles. In the second step, 8Be + 4He has almost exactly the energy of an exci ...
... temperatures of 100.000.000 K. 8Be is unstable and decays back into He in 2.6 × 10–16 secs, but in the stellar interior a small equilibrium of 8Be exists. The 8Be ground state has almost exactly the energy of two alpha particles. In the second step, 8Be + 4He has almost exactly the energy of an exci ...
The Sun . . .
... 90% of stars are main sequence. Supergiant: 20 to 200 times larger than the Sun, but also much brighter, cooler and less dense. Dwarf: Small stars; fairly hot but very dim. Diameter is about the same as Earth, but their mass is equal to the sun . . . ...
... 90% of stars are main sequence. Supergiant: 20 to 200 times larger than the Sun, but also much brighter, cooler and less dense. Dwarf: Small stars; fairly hot but very dim. Diameter is about the same as Earth, but their mass is equal to the sun . . . ...
The Hidden Lives of Galaxies NSTA 2001
... Fusion begins Energy released from nuclear fusion counter-acts inward force of gravity. ...
... Fusion begins Energy released from nuclear fusion counter-acts inward force of gravity. ...
Planetary Configurations
... so m relates to apparent brightness • Absolute magnitude M is m at a particular distance, namely 10 parsecs, so M = -2.5 log [ L / 4p (10 pcs)2 ] + constant so M relates to intrinsic brightness, in terms of luminosity • Distance modulus is a way of relating an object’s distance to its magnitude m - ...
... so m relates to apparent brightness • Absolute magnitude M is m at a particular distance, namely 10 parsecs, so M = -2.5 log [ L / 4p (10 pcs)2 ] + constant so M relates to intrinsic brightness, in terms of luminosity • Distance modulus is a way of relating an object’s distance to its magnitude m - ...
The power plant of the Sun and stars
... MS stars fuse hydrogen into helium, releasing prodigious amounts of energy in the process. Their fuel source is the matter of which they are made ...
... MS stars fuse hydrogen into helium, releasing prodigious amounts of energy in the process. Their fuel source is the matter of which they are made ...
Solar Furnaces
... • If M < 0.08 Msun, then T is not high enough for sustained nuclear reactions: get a “BROWN DWARF” (failed star) (But fusion does occur for a short time.) • It is held up by “degeneracy pressure” (quantum mechanical pressure). • Until the mid-1990s, no confirmed brown dwarfs had been found, but now ...
... • If M < 0.08 Msun, then T is not high enough for sustained nuclear reactions: get a “BROWN DWARF” (failed star) (But fusion does occur for a short time.) • It is held up by “degeneracy pressure” (quantum mechanical pressure). • Until the mid-1990s, no confirmed brown dwarfs had been found, but now ...
A small mass difference between Hydrogen and Helium The
... Sun, but what is going on on the rest of the Main Sequence? ...
... Sun, but what is going on on the rest of the Main Sequence? ...
Integrative Studies 410 Our Place in the Universe
... distance ladder out as far as we can see Cepheids – about 50 million ly • In 1920 Hubble used this technique to measure the distance to Andromeda (about 2 million ly) • Works best for periodic variables ...
... distance ladder out as far as we can see Cepheids – about 50 million ly • In 1920 Hubble used this technique to measure the distance to Andromeda (about 2 million ly) • Works best for periodic variables ...
Shocking Truth about Massive Stars Lidia Oskinova Chandra’s First Decade of Discovery
... ’’A very energetic explosion of a massive star is likely to create a ... fireball.... the inner core of a massive, rapidly rotating star collapses into a ~10 M Kerr black hole ... A superstrong ~10 15 G magnetic field is needed to make the object ... a microquasar. Such events must be vary rare...to ...
... ’’A very energetic explosion of a massive star is likely to create a ... fireball.... the inner core of a massive, rapidly rotating star collapses into a ~10 M Kerr black hole ... A superstrong ~10 15 G magnetic field is needed to make the object ... a microquasar. Such events must be vary rare...to ...
Chapter 07
... Analyzing Absorption Spectra • Each element produces a specific set of absorption and emission lines. • Comparing the relative strengths of these sets of lines, we can study the gases from stars. Where to ...
... Analyzing Absorption Spectra • Each element produces a specific set of absorption and emission lines. • Comparing the relative strengths of these sets of lines, we can study the gases from stars. Where to ...
Integrative Studies 410 Our Place in the Universe
... • Light elements (hydrogen, helium) formed in Big Bang • Heavier elements formed by nuclear fusion in stars and thrown into space by supernovae – Condense into new stars and planets – Elements heavier than iron form during supernovae explosions ...
... • Light elements (hydrogen, helium) formed in Big Bang • Heavier elements formed by nuclear fusion in stars and thrown into space by supernovae – Condense into new stars and planets – Elements heavier than iron form during supernovae explosions ...
Stars and Galaxies
... • Not all stars are the same color because different elements burn different colors. Some are red, some are blue, etc. • Color tells the temperature of the star • Hot stars are bluish/white and cooler stars are reddish/orange • Astronomers call this a star’s spectral class. Spectral classes are O, B ...
... • Not all stars are the same color because different elements burn different colors. Some are red, some are blue, etc. • Color tells the temperature of the star • Hot stars are bluish/white and cooler stars are reddish/orange • Astronomers call this a star’s spectral class. Spectral classes are O, B ...
The Mass-Luminosity Relationship and Stellar Lifetimes
... • Our intuition would seem to say that since big stars have a lot more fuel to consume, they should last a lot longer than smaller stars. • It doesn’t work this way, however. If the luminosity of a star increases with the 4th power of the mass, that means that the star is producing energy and using ...
... • Our intuition would seem to say that since big stars have a lot more fuel to consume, they should last a lot longer than smaller stars. • It doesn’t work this way, however. If the luminosity of a star increases with the 4th power of the mass, that means that the star is producing energy and using ...
Futuro da Ci^encia no IAG
... GRB at z~8.2 = pop. III? -First generations of low mass stars should be still evolving, identified by a very low metallicity (or no metals) (z ~ 5 to 15) ...
... GRB at z~8.2 = pop. III? -First generations of low mass stars should be still evolving, identified by a very low metallicity (or no metals) (z ~ 5 to 15) ...
From the Everett and Seattle Astronomical
... There are several types of nebulae. Emission nebulae are clouds of high temperature gas. The atoms in the cloud are energized by ultraviolet light from a nearby star and emit radiation as they fall back into lower energy states. Emission nebulae are sites of recent and ongoing star formation. The Or ...
... There are several types of nebulae. Emission nebulae are clouds of high temperature gas. The atoms in the cloud are energized by ultraviolet light from a nearby star and emit radiation as they fall back into lower energy states. Emission nebulae are sites of recent and ongoing star formation. The Or ...
NASAexplores 9-12 Lesson: Classified Stars - Science
... you while gazing into the night sky. The absolute magnitude and luminosity are used for that. They give you the relative brightness based on all of the stars being the same distance away from the earth. On this diagram, you do not see all of the individual stars. Since there are so many stars, only ...
... you while gazing into the night sky. The absolute magnitude and luminosity are used for that. They give you the relative brightness based on all of the stars being the same distance away from the earth. On this diagram, you do not see all of the individual stars. Since there are so many stars, only ...
Measuring stars Part I
... •Vega is 22 light years away—its in the neighborhood •Note that Altair (about 30 lyrs) is probably flattened..its rotating very fast! •Apparent brightness depends on size, temp, and distance! ...
... •Vega is 22 light years away—its in the neighborhood •Note that Altair (about 30 lyrs) is probably flattened..its rotating very fast! •Apparent brightness depends on size, temp, and distance! ...
3.2 Spectra and Spectral Classification
... Brightness temperature: T. of a blackbody with the same flux density at some wavelength Kinetic temperature: related to the average speed of the gas particles Ionization temperature: T. necessary for ionizing the gas Remark: Since the stars are not exactly blackbodies, the values for the different t ...
... Brightness temperature: T. of a blackbody with the same flux density at some wavelength Kinetic temperature: related to the average speed of the gas particles Ionization temperature: T. necessary for ionizing the gas Remark: Since the stars are not exactly blackbodies, the values for the different t ...
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.