PPT
... The Puzzle of “Spiral Nebulae” • Before Edwin Hubble, some scientists argued that “spiral nebulae” were entire galaxies like our Milky Way, while others maintained they were smaller collections of stars within the Milky Way • Hubble settled the debate by measuring the distance to the Andromeda Galax ...
... The Puzzle of “Spiral Nebulae” • Before Edwin Hubble, some scientists argued that “spiral nebulae” were entire galaxies like our Milky Way, while others maintained they were smaller collections of stars within the Milky Way • Hubble settled the debate by measuring the distance to the Andromeda Galax ...
OGU - What`s Out Tonight?
... galaxies, there is little gas and dust to form new stars. A second type of galaxy is the spiral, which resembles its name. The galaxy that we live in, the Milky Way Galaxy, is a spiral. Spirals are flatter looking, like a dish. They have round bulged centers out of which curved arms radiate. Spirals ...
... galaxies, there is little gas and dust to form new stars. A second type of galaxy is the spiral, which resembles its name. The galaxy that we live in, the Milky Way Galaxy, is a spiral. Spirals are flatter looking, like a dish. They have round bulged centers out of which curved arms radiate. Spirals ...
Introduction to Observational Cosmology
... about 1 L* galaxy / 100 Mpc3 ; M* (now)=-20.8 in r-band (Note: by convention H0=100) Schechter function is a good representation LF (= abundance distribution) depends on the intrinsic color of the galaxy Vatican 2003 Lecture 20 HWR ...
... about 1 L* galaxy / 100 Mpc3 ; M* (now)=-20.8 in r-band (Note: by convention H0=100) Schechter function is a good representation LF (= abundance distribution) depends on the intrinsic color of the galaxy Vatican 2003 Lecture 20 HWR ...
Chapter 17 - Astronomy
... 1. In 1912, Slipher found that spiral nebulae had redshifted spectra indicating that they were moving away from us at tremendous velocity. 2. In 1920s, Hubble and Humason showed that there is a relationship between the recessional velocities of galaxies and their distances. 3. Hubble showed that the ...
... 1. In 1912, Slipher found that spiral nebulae had redshifted spectra indicating that they were moving away from us at tremendous velocity. 2. In 1920s, Hubble and Humason showed that there is a relationship between the recessional velocities of galaxies and their distances. 3. Hubble showed that the ...
The Galaxy Luminosity Function
... Half of the luminosity density is contributed by galaxies with L/L* > ½. Though the number density diverges, we can determine the number density of galaxies in units of Milky Ways, ...
... Half of the luminosity density is contributed by galaxies with L/L* > ½. Though the number density diverges, we can determine the number density of galaxies in units of Milky Ways, ...
Beatrice Muriel Hill Tinsley
... other women astronomers whose early work made a big difference in important parts of astronomy. The first was Cecilia Helena Payne, who became a Gaposchkin by marriage. Born in England (again!) in 1900, she completed a PhD dissertation at Harvard in 1925 which established two very fundamental things ...
... other women astronomers whose early work made a big difference in important parts of astronomy. The first was Cecilia Helena Payne, who became a Gaposchkin by marriage. Born in England (again!) in 1900, she completed a PhD dissertation at Harvard in 1925 which established two very fundamental things ...
Chapter 17
... 1. In 1912, Slipher found that spiral nebulae had redshifted spectra indicating that they were moving away from us at tremendous velocity. 2. In 1920s, Hubble and Humason showed that there is a relationship between the recessional velocities of galaxies and their distances. 3. Hubble showed that the ...
... 1. In 1912, Slipher found that spiral nebulae had redshifted spectra indicating that they were moving away from us at tremendous velocity. 2. In 1920s, Hubble and Humason showed that there is a relationship between the recessional velocities of galaxies and their distances. 3. Hubble showed that the ...
AGN Science Collaboration - Active Galactic Nuclei Science
... - bias against AGN in SF galaxies - bias against low Eddington ratios • Selection bias can be partially overcome by: - variability (at least with nearby objects) - X-rays (not as deep as LSST) • LSST photometry / depth makes this problem more challenging than previous optical surveys. ...
... - bias against AGN in SF galaxies - bias against low Eddington ratios • Selection bias can be partially overcome by: - variability (at least with nearby objects) - X-rays (not as deep as LSST) • LSST photometry / depth makes this problem more challenging than previous optical surveys. ...
Redshift
In physics, redshift happens when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum. In general, whether or not the radiation is within the visible spectrum, ""redder"" means an increase in wavelength – equivalent to a lower frequency and a lower photon energy, in accordance with, respectively, the wave and quantum theories of light.Some redshifts are an example of the Doppler effect, familiar in the change of apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles. A redshift occurs whenever a light source moves away from an observer. Another kind of redshift is cosmological redshift, which is due to the expansion of the universe, and sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase in their distance from Earth. Finally, gravitational redshift is a relativistic effect observed in electromagnetic radiation moving out of gravitational fields. Conversely, a decrease in wavelength is called blueshift and is generally seen when a light-emitting object moves toward an observer or when electromagnetic radiation moves into a gravitational field. However, redshift is a more common term and sometimes blueshift is referred to as negative redshift.Knowledge of redshifts and blueshifts has been applied to develop several terrestrial technologies such as Doppler radar and radar guns. Redshifts are also seen in the spectroscopic observations of astronomical objects. Its value is represented by the letter z.A special relativistic redshift formula (and its classical approximation) can be used to calculate the redshift of a nearby object when spacetime is flat. However, in many contexts, such as black holes and Big Bang cosmology, redshifts must be calculated using general relativity. Special relativistic, gravitational, and cosmological redshifts can be understood under the umbrella of frame transformation laws. There exist other physical processes that can lead to a shift in the frequency of electromagnetic radiation, including scattering and optical effects; however, the resulting changes are distinguishable from true redshift and are not generally referred to as such (see section on physical optics and radiative transfer).