The Transfer Equation
... Teff = 4500 K. The two stars are of nearly equal V magnitude. What is the ratio of their fluxes at 2 microns? • In an eclipsing binary system, comprised of a B5V star at Teff = 16,000K and an F0III star at Teff = 7000K, the two stars are known to have nearly equal diameters. How deep will the primar ...
... Teff = 4500 K. The two stars are of nearly equal V magnitude. What is the ratio of their fluxes at 2 microns? • In an eclipsing binary system, comprised of a B5V star at Teff = 16,000K and an F0III star at Teff = 7000K, the two stars are known to have nearly equal diameters. How deep will the primar ...
Volume 20 Number 10 September 2012
... On July 23rd, a massive cloud of solar material erupted off the Sun’s right side and zoomed out into space. Scientists clocked this giant cloud (a coronal mass ejection) as traveling between 1,800 to 2,200 miles per second as it left the Sun. This was the fastest CME ever observed by the STEREO spac ...
... On July 23rd, a massive cloud of solar material erupted off the Sun’s right side and zoomed out into space. Scientists clocked this giant cloud (a coronal mass ejection) as traveling between 1,800 to 2,200 miles per second as it left the Sun. This was the fastest CME ever observed by the STEREO spac ...
Signatures of the first stars in the 21cm Emission and Absorption
... • Central gas cools only to T ≈ 200 K. Molecular hydrogen lines can be collisionally deexcited at density n > 104 cm-3, making the cooling rate independent of density and inhibiting fragmentation. • Jeans mass ≈ 300 Msun . • Accretion rate ≈ cs3/G ≈ 10-3 Msun/yr • The first metal-free stars were mas ...
... • Central gas cools only to T ≈ 200 K. Molecular hydrogen lines can be collisionally deexcited at density n > 104 cm-3, making the cooling rate independent of density and inhibiting fragmentation. • Jeans mass ≈ 300 Msun . • Accretion rate ≈ cs3/G ≈ 10-3 Msun/yr • The first metal-free stars were mas ...
5 Elements of nuclear physics 5.1 Strong interaction and structure of atomic nuclei
... This is the Chandrasekhar mass, the maximal possible mass of the white dwarf. For larger masses, the pressure of degenerate electrons is unable to balance the gravity force therefore the star collapses into the neutron star or black hole. Numerically MCh = 1.4MJ . In neutron stars, the gravity force ...
... This is the Chandrasekhar mass, the maximal possible mass of the white dwarf. For larger masses, the pressure of degenerate electrons is unable to balance the gravity force therefore the star collapses into the neutron star or black hole. Numerically MCh = 1.4MJ . In neutron stars, the gravity force ...
Diapositiva 1
... Side View of the Milky Way The “halo” is really the “stellar halo” – turns out there’s actually a larger halo we can’t even see! ...
... Side View of the Milky Way The “halo” is really the “stellar halo” – turns out there’s actually a larger halo we can’t even see! ...
Constellation Part II readingConstellation Part II reading(es)
... Why Do Most Stars and Constellations Move? The stars are distant objects. Their distances vary, but they are all very far away. Excluding our Sun, the nearest star, Proxima Centauri, is more than 4 light years away. As Earth spins on its axis, we, as Earth-bound observers, spin past this background ...
... Why Do Most Stars and Constellations Move? The stars are distant objects. Their distances vary, but they are all very far away. Excluding our Sun, the nearest star, Proxima Centauri, is more than 4 light years away. As Earth spins on its axis, we, as Earth-bound observers, spin past this background ...
luminosities
... Example: Star Radii Polaris has just about the same spectral type (and thus surface temperature) as our sun, but it is 10,000 times brighter than our sun. ...
... Example: Star Radii Polaris has just about the same spectral type (and thus surface temperature) as our sun, but it is 10,000 times brighter than our sun. ...
When you look up at the night sky, thousands of objects
... extremely massive stars age, they begin to collapse. Scientists think the matter in these stars is drawn inward, creating an extremely small yet dense object. A black hole the size of a pea could have the mass of Earth! Scientists once assumed the gravity of black holes pulled everything into them f ...
... extremely massive stars age, they begin to collapse. Scientists think the matter in these stars is drawn inward, creating an extremely small yet dense object. A black hole the size of a pea could have the mass of Earth! Scientists once assumed the gravity of black holes pulled everything into them f ...
AmiraPoster3
... by a precessing accretion disk. • Mode of mass transfer believed to have significant contributions from Roche-lobe overflow, as the stellar winds observed in Sk 160 are not strong enough to power accretion from the secondary onto the primary. • Mass of the neutron star was first found using image-tu ...
... by a precessing accretion disk. • Mode of mass transfer believed to have significant contributions from Roche-lobe overflow, as the stellar winds observed in Sk 160 are not strong enough to power accretion from the secondary onto the primary. • Mass of the neutron star was first found using image-tu ...
Time From the Perspective of a Particle Physicist
... 1. Determine Surface Temperature + spectral class of star 2. Determine where on HR diagram should go 3. Read off absolute luminosity from HR diagram 4. Measure apparent luminosity and calculate distance • works best if many close-by stars ...
... 1. Determine Surface Temperature + spectral class of star 2. Determine where on HR diagram should go 3. Read off absolute luminosity from HR diagram 4. Measure apparent luminosity and calculate distance • works best if many close-by stars ...
A Star is a ball of matter that is pulled together by gravity, and that
... –Scientists determine the composition by studying the _________________that comes from a star. How Light shows composition: when elements in a star burn, they give off certain colors of light. The ____________of _____________ corresponds to a specific _____________________of the light. ...
... –Scientists determine the composition by studying the _________________that comes from a star. How Light shows composition: when elements in a star burn, they give off certain colors of light. The ____________of _____________ corresponds to a specific _____________________of the light. ...
Project 4: The HR diagram. Open clusters
... or spectral class, while the vertical axis can be luminosity with respect to that of the Sun or the absolute magnitude MV. When luminosity is plotted as a function of the temperature for a large number of stars, stars do not fall randomly on the graph; rather they are confined to specific regions. T ...
... or spectral class, while the vertical axis can be luminosity with respect to that of the Sun or the absolute magnitude MV. When luminosity is plotted as a function of the temperature for a large number of stars, stars do not fall randomly on the graph; rather they are confined to specific regions. T ...
Lecture 18
... • Stars make new elements by fusion. • Dying stars expel gas and new elements, producing hot bubbles (~106 K). • Hot gas cools, allowing atomic hydrogen clouds to form (~100–10,000 K). • Further cooling permits molecules to form, making molecular clouds (~30 K). • Gravity forms new stars (and planet ...
... • Stars make new elements by fusion. • Dying stars expel gas and new elements, producing hot bubbles (~106 K). • Hot gas cools, allowing atomic hydrogen clouds to form (~100–10,000 K). • Further cooling permits molecules to form, making molecular clouds (~30 K). • Gravity forms new stars (and planet ...
The Temperature of Stars
... Because different elements absorb different wavelengths of light, scientists can determine the elements that make up a star by studying its spectrum. ...
... Because different elements absorb different wavelengths of light, scientists can determine the elements that make up a star by studying its spectrum. ...
Astronomy Directed Reading
... 19. How do the inner planets differ from the outer planets? __________________________________ _________________________________________________________________________________ 20. How did distance from the sun affect the formation of the outer planets? ____________________ _________________________ ...
... 19. How do the inner planets differ from the outer planets? __________________________________ _________________________________________________________________________________ 20. How did distance from the sun affect the formation of the outer planets? ____________________ _________________________ ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.