Galaxy Evolution
... has been shown that such ideas were incorrect, nonetheless the nomenclature has remained, and today it is common, for example, to refer to ellipticals and lenticulars as ‘earlytype galaxies’. The luminosity function One very powerful tool that describes in a quantitative way two of the most importan ...
... has been shown that such ideas were incorrect, nonetheless the nomenclature has remained, and today it is common, for example, to refer to ellipticals and lenticulars as ‘earlytype galaxies’. The luminosity function One very powerful tool that describes in a quantitative way two of the most importan ...
THE LUMINOSITY FUNCTION OF X
... (2Y8 keV) X-rayYselected surveys (Cowie et al. 2003; Ueda et al. 2003; Fiore et al. 2003; Barger et al. 2003b, 2005; Silverman et al. 2005b; La Franca et al. 2005). Using a highly complete soft (0.5Y2.0 keV) band selected sample of over 1000 type 1 AGNs, Hasinger et al. (2005) have shown that this L ...
... (2Y8 keV) X-rayYselected surveys (Cowie et al. 2003; Ueda et al. 2003; Fiore et al. 2003; Barger et al. 2003b, 2005; Silverman et al. 2005b; La Franca et al. 2005). Using a highly complete soft (0.5Y2.0 keV) band selected sample of over 1000 type 1 AGNs, Hasinger et al. (2005) have shown that this L ...
The Milky Way - The Independent School
... As you begin studying galaxies, you will discover they are classified into different types, and that will lead you to insights into how galaxies form and evolve. In the next chapter, you will discover that some galaxies are violently active, and that will give you more clues to the evolution of gala ...
... As you begin studying galaxies, you will discover they are classified into different types, and that will lead you to insights into how galaxies form and evolve. In the next chapter, you will discover that some galaxies are violently active, and that will give you more clues to the evolution of gala ...
R - Institut d`Astrophysique de Paris
... SVOM = Space-based multiband astronomical Variable Objects Monitor ...
... SVOM = Space-based multiband astronomical Variable Objects Monitor ...
REVIEWS 18 years of science with the Hubble Space Telescope Julianne J. Dalcanton
... resulting improvements is the dramatic increase in a telescope’s resolution—the smallest angular separation that can be reliably detected (Fig. 2). Images taken with the HST can distinguish features that are separated by less than a tenth of an arc second (comparable to the angle spanned by half a m ...
... resulting improvements is the dramatic increase in a telescope’s resolution—the smallest angular separation that can be reliably detected (Fig. 2). Images taken with the HST can distinguish features that are separated by less than a tenth of an arc second (comparable to the angle spanned by half a m ...
Chapter 31: Galaxies and the Universe
... astronomers been able to determine its shape. This is because radio waves can penetrate the interstellar gas and dust without being scattered or absorbed. Astronomers have discovered, by measuring radio waves as well as infrared radiation, that the galactic center, also called the nucleus, is surrou ...
... astronomers been able to determine its shape. This is because radio waves can penetrate the interstellar gas and dust without being scattered or absorbed. Astronomers have discovered, by measuring radio waves as well as infrared radiation, that the galactic center, also called the nucleus, is surrou ...
The Universe - the Scientia Review
... are similar to spiral or elliptical galaxies. Much like the spiral galaxy, lenticular masses have spiral arms; however, lenticular curves are not quite as distinct. In addition, lenticular galaxies have a disk-like This lenticular galaxy has both the brightness of an elliptical galaxy and shape, whi ...
... are similar to spiral or elliptical galaxies. Much like the spiral galaxy, lenticular masses have spiral arms; however, lenticular curves are not quite as distinct. In addition, lenticular galaxies have a disk-like This lenticular galaxy has both the brightness of an elliptical galaxy and shape, whi ...
– 1 – 1. Galaxy Observations 1.1.
... rate affecting the UV continuum, and the calibration for UV stellar photospheric features or UV ISM absorption to metallicity is not well understood at present (see Erb 2010 for details). So the best approach is to move into the near-IR, where the normal optical low redshift techniques and calibrati ...
... rate affecting the UV continuum, and the calibration for UV stellar photospheric features or UV ISM absorption to metallicity is not well understood at present (see Erb 2010 for details). So the best approach is to move into the near-IR, where the normal optical low redshift techniques and calibrati ...
Galaxies
... perhaps not surprising that this property should be related to luminosity. What is surprising, though, is how tight the correlation is. The Tully-Fisher relation, as it is now known (after its discoverers), allows us to obtain a remarkably accurate estimate of a spiral galaxy’s luminosity simply by ...
... perhaps not surprising that this property should be related to luminosity. What is surprising, though, is how tight the correlation is. The Tully-Fisher relation, as it is now known (after its discoverers), allows us to obtain a remarkably accurate estimate of a spiral galaxy’s luminosity simply by ...
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).