The Milky Way galaxy Contents Summary
... Galaxies vary enormously in size from objects that contain only 100 000 stars, to ones with hundreds of billions of stars. The smaller galaxies are much more numerous than the larger ones, but not by a sufficient factor to compensate for their lower luminosities. So most of the luminosity in the Uni ...
... Galaxies vary enormously in size from objects that contain only 100 000 stars, to ones with hundreds of billions of stars. The smaller galaxies are much more numerous than the larger ones, but not by a sufficient factor to compensate for their lower luminosities. So most of the luminosity in the Uni ...
P - Inaf
... How much do aperture and resolution effects bias the comparison between observations at different redshifts and with models? ...
... How much do aperture and resolution effects bias the comparison between observations at different redshifts and with models? ...
Thermal history of the universe with dark energy
... Near the end of the twentieth century, the astronomical observations on the redshift of supernovae [5, 6] showed that the universe was expanding at an accelerated rate, which justified the introduction of an entity with negative pressure to account for it, the dark energy. This revived the cosmologi ...
... Near the end of the twentieth century, the astronomical observations on the redshift of supernovae [5, 6] showed that the universe was expanding at an accelerated rate, which justified the introduction of an entity with negative pressure to account for it, the dark energy. This revived the cosmologi ...
File 11 - School of Astronomy, IPM
... stellar disks • S0 galaxies also have bars – a bar can persist in the absence of gas • Bar patterns are not static, they rotate with a pattern speed, but unlike spiral arms they are not density waves. Stars in the bar stay in the bar • The asymmetric gravitational forces of a disk allow gas to lose ...
... stellar disks • S0 galaxies also have bars – a bar can persist in the absence of gas • Bar patterns are not static, they rotate with a pattern speed, but unlike spiral arms they are not density waves. Stars in the bar stay in the bar • The asymmetric gravitational forces of a disk allow gas to lose ...
The star formation history of galaxies in 3D: CALIFA perspective
... (Blanton & Moustakas 2009), following well the Hubble tuning-fork diagram. The bulge fraction seems to be one of the main physical parameters that produce the Hubble sequence, increasing from late to early spirals. In this scheme, S0 galaxies are a transition class between the spiral classes and the ...
... (Blanton & Moustakas 2009), following well the Hubble tuning-fork diagram. The bulge fraction seems to be one of the main physical parameters that produce the Hubble sequence, increasing from late to early spirals. In this scheme, S0 galaxies are a transition class between the spiral classes and the ...
Studies of dark matter in and around stars
... was that the mass distribution does not follow the gas distribution as would be expected in a world without dark matter [5]. In contrast to galactic rotation curves, this is very difficult to explain by modifying gravity, since one has to dislocate the gravitational impact from the source. To explai ...
... was that the mass distribution does not follow the gas distribution as would be expected in a world without dark matter [5]. In contrast to galactic rotation curves, this is very difficult to explain by modifying gravity, since one has to dislocate the gravitational impact from the source. To explai ...
12.1 Elliptical galaxies
... kinetic energy can be characterized by a velocity dispersion. You can think of the distribution as being pretty close to Gaussian. Because they're supported by random motions rather than rotation, they're called pressure-supported systems. The way we usually measure this is thr ...
... kinetic energy can be characterized by a velocity dispersion. You can think of the distribution as being pretty close to Gaussian. Because they're supported by random motions rather than rotation, they're called pressure-supported systems. The way we usually measure this is thr ...
Theory of Motion of Matter on the Formation of Galaxy and Star
... outwards primordial galaxy nebula center high density nuclear zone and dispersed matter, which has changed the motion direction of dispersed matter and made it move towards nebula center. Energy change occurs between primordial galaxy nebula center high density nuclear zone and dispersed matter, pro ...
... outwards primordial galaxy nebula center high density nuclear zone and dispersed matter, which has changed the motion direction of dispersed matter and made it move towards nebula center. Energy change occurs between primordial galaxy nebula center high density nuclear zone and dispersed matter, pro ...
Dark matter
... cosmologies, however, do not actually ascribe any 'physicality' to space. The Big Bang is a cosmological model of the universe that has become well supported by several independent observations. After Edwin Hubble discovered that galactic distances were generally proportional to their redshifts in 1 ...
... cosmologies, however, do not actually ascribe any 'physicality' to space. The Big Bang is a cosmological model of the universe that has become well supported by several independent observations. After Edwin Hubble discovered that galactic distances were generally proportional to their redshifts in 1 ...
The Formation and Evolution of Massive Black Holes - Ira-Inaf
... massive star is to collapse into a black hole with a mass similar to that of its progenitor. However, this is not the case when the content of heavy elements increases. In today’s universe, a very massive star would lose most of its mass in powerful winds before collapsing into a stellar mass black ...
... massive star is to collapse into a black hole with a mass similar to that of its progenitor. However, this is not the case when the content of heavy elements increases. In today’s universe, a very massive star would lose most of its mass in powerful winds before collapsing into a stellar mass black ...
1 Introduction - Wiley-VCH
... and lenticulars for 20% [12]. The fraction of late-type galaxies, however, strongly decreases in high-density environments such as in rich clusters [13, 14]. Dwarfs exceed in number massive objects. However, despite their relatively low number, ellipticals, lenticulars, and spiral bulges contain ...
... and lenticulars for 20% [12]. The fraction of late-type galaxies, however, strongly decreases in high-density environments such as in rich clusters [13, 14]. Dwarfs exceed in number massive objects. However, despite their relatively low number, ellipticals, lenticulars, and spiral bulges contain ...
The nature of the ultraluminous X-ray sources inside galaxies and
... (2000) are also QSOs in the process of ejection. If M 82 was observed at the distance of Arp 220, all of the QSOs which we have found to be associated with it would be much too faint, and much too close to the main body of the galaxy to be detectable. However, they will contribute significantly to i ...
... (2000) are also QSOs in the process of ejection. If M 82 was observed at the distance of Arp 220, all of the QSOs which we have found to be associated with it would be much too faint, and much too close to the main body of the galaxy to be detectable. However, they will contribute significantly to i ...
Dark matter
Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but would account for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, on radiation, and on the large-scale structure of the universe. Dark matter has not been detected directly, making it one of the greatest mysteries in modern astrophysics.Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy. Thus, dark matter is estimated to constitute 84.5% of the total matter in the universe, while dark energy plus dark matter constitute 95.1% of the total mass–energy content of the universe.Astrophysicists hypothesized the existence of dark matter to account for discrepancies between the mass of large astronomical objects determined from their gravitational effects, and their mass as calculated from the observable matter (stars, gas, and dust) that they can be seen to contain. Their gravitational effects suggest that their masses are much greater than the observable matter survey suggests. Dark matter was postulated by Jan Oort in 1932, albeit based upon insufficient evidence, to account for the orbital velocities of stars in the Milky Way. In 1933, Fritz Zwicky was the first to use the virial theorem to infer the existence of unseen matter, which he referred to as dunkle Materie 'dark matter'. More robust evidence from galaxy rotation curves was discovered by Horace W. Babcock in 1939, but was not attributed to dark matter. The first hypothesis to postulate ""dark matter"" based upon robust evidence was formulated by Vera Rubin and Kent Ford in the 1960s–1970s, using galaxy rotation curves. Subsequently, many other observations have indicated the presence of dark matter in the universe, including gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, the temperature distribution of hot gas in galaxies and clusters of galaxies and, more recently, the pattern of anisotropies in the cosmic microwave background. According to consensus among cosmologists, dark matter is composed primarily of a not yet characterized type of subatomic particle.The search for this particle, by a variety of means, is one of the major efforts in particle physics today.Although the existence of dark matter is generally accepted by the mainstream scientific community, some alternative theories of gravity have been proposed, such as MOND and TeVeS, which try to account for the anomalous observations without requiring additional matter. However, these theories cannot account for the properties of galaxy clusters.