Astronomy Chapter 17 – Galaxies A. Main Ideas 1. Discovering
... ⇒ A Seyfert galaxy is a spiral galaxy whose nucleus is abnormally luminous. The core luminosity of a Seyfert galaxy is immense, amounting to the entire radiation output of the Milky Way, but coming from a region less than one light-year across • Quasars ⇒ Quasars are extremely luminous, extremely di ...
... ⇒ A Seyfert galaxy is a spiral galaxy whose nucleus is abnormally luminous. The core luminosity of a Seyfert galaxy is immense, amounting to the entire radiation output of the Milky Way, but coming from a region less than one light-year across • Quasars ⇒ Quasars are extremely luminous, extremely di ...
The cosmic distance scale
... dwarf star of the system explodes when it reaches a certain mass (which applies everywhere in the universe). This is however not exactly true, different white dwarfs have different atmospheric compositions and this in turn affects both how fast the supernovae fade and how bright they become, see Fig ...
... dwarf star of the system explodes when it reaches a certain mass (which applies everywhere in the universe). This is however not exactly true, different white dwarfs have different atmospheric compositions and this in turn affects both how fast the supernovae fade and how bright they become, see Fig ...
The Search for the Earliest Galaxies
... holes at their cores with gas. The accretion of material onto the black holes produced quasars which then emitted powerful, far-ultraviolet radiation that provided enough energy to reionize the helium. This radiation also interrupted the growth of some small galaxies because the gas clouds within th ...
... holes at their cores with gas. The accretion of material onto the black holes produced quasars which then emitted powerful, far-ultraviolet radiation that provided enough energy to reionize the helium. This radiation also interrupted the growth of some small galaxies because the gas clouds within th ...
Here
... It is not possible to see individual stars in galaxies beyond 10-20 Mpc. Hence the stellar populations characteristics of E galaxies must be derived from the integrated colors and spectra. As we saw before, the spectra of an E galaxy resembles that of a K giant ...
... It is not possible to see individual stars in galaxies beyond 10-20 Mpc. Hence the stellar populations characteristics of E galaxies must be derived from the integrated colors and spectra. As we saw before, the spectra of an E galaxy resembles that of a K giant ...
X-Ray Binaries
... . as seeds for star formation (triggering the collapse of gas clouds) . dark matter in galactic halos . forming the cores of globular clusters • argument in support: soft X-ray spectrum • association with starburst galaxies, interacting galaxies (e.g. Antennae) but: GRS 1915+105 is a Galactic counte ...
... . as seeds for star formation (triggering the collapse of gas clouds) . dark matter in galactic halos . forming the cores of globular clusters • argument in support: soft X-ray spectrum • association with starburst galaxies, interacting galaxies (e.g. Antennae) but: GRS 1915+105 is a Galactic counte ...
Expanding Universe and Big Bang
... Similarly, if the source is moving away from you, each successive wave has further to travel and so you observe a lower frequency (less than one wave per second). So there is a difference between the source frequency and the observed frequency. Doppler realized that this would also affect the wavele ...
... Similarly, if the source is moving away from you, each successive wave has further to travel and so you observe a lower frequency (less than one wave per second). So there is a difference between the source frequency and the observed frequency. Doppler realized that this would also affect the wavele ...
Gone in a flash: supernovae in the survey era
... brighter than a Type Ia supernova). The first of SLSN (Gal-Yam 2012), commonly defined as CFHT, or DECam on the Cerro Tololo Interevent, SCP 06F6, was identified in 2009 and had being brighter than –21 in absolute magnitude American Observatory 4 m Blanco telescope), broad, unexplained spectral abso ...
... brighter than a Type Ia supernova). The first of SLSN (Gal-Yam 2012), commonly defined as CFHT, or DECam on the Cerro Tololo Interevent, SCP 06F6, was identified in 2009 and had being brighter than –21 in absolute magnitude American Observatory 4 m Blanco telescope), broad, unexplained spectral abso ...
vswisher_sigmaxiposter2004
... Each individual emission line comes from an element that has been ionized in the hot X-ray emitting plasma. An emission line can be broad due to the Doppler shift: photons will be bluer or redder depending on their direction of motion, resulting in an overall broad line. We care about the Doppler sh ...
... Each individual emission line comes from an element that has been ionized in the hot X-ray emitting plasma. An emission line can be broad due to the Doppler shift: photons will be bluer or redder depending on their direction of motion, resulting in an overall broad line. We care about the Doppler sh ...
Document
... 4. The cosmic distance ladder • This lecture: • Measuring distances to – things within the solar system – things within the solar neighbourhood – things within the galaxy – nearby galaxies – distant galaxies ...
... 4. The cosmic distance ladder • This lecture: • Measuring distances to – things within the solar system – things within the solar neighbourhood – things within the galaxy – nearby galaxies – distant galaxies ...
Introduction
... A galaxy is a self-gravitating system composed of an interstellar medium, stars, and dark matter. It’s difficult to overstate the role of gravity in galaxies. While the electromagnetic force has the same r 2 dependence as gravity, charge cancellation insures that large-scale electromagnetic forces a ...
... A galaxy is a self-gravitating system composed of an interstellar medium, stars, and dark matter. It’s difficult to overstate the role of gravity in galaxies. While the electromagnetic force has the same r 2 dependence as gravity, charge cancellation insures that large-scale electromagnetic forces a ...
Galaxies
... 5. Limitations of the model There are several limitations of our computer model. First, it is only a two-dimensional demonstration of the galactic collision, but actually, the stars in the galaxies do not completely lie on the same plane. As a result, the model does not consider the 3-D component of ...
... 5. Limitations of the model There are several limitations of our computer model. First, it is only a two-dimensional demonstration of the galactic collision, but actually, the stars in the galaxies do not completely lie on the same plane. As a result, the model does not consider the 3-D component of ...
Word
... 5. Limitations of the model There are several limitations of our computer model. First, it is only a two-dimensional demonstration of the galactic collision, but actually, the stars in the galaxies do not completely lie on the same plane. As a result, the model does not consider the 3-D component of ...
... 5. Limitations of the model There are several limitations of our computer model. First, it is only a two-dimensional demonstration of the galactic collision, but actually, the stars in the galaxies do not completely lie on the same plane. As a result, the model does not consider the 3-D component of ...
Cosmological Aspects of Nucleosynthesis
... The decrease of below 4/3 is a consequence of the new particles which do not immediately add their contribution to the total pressure.. At high densities: >4/3, because the electron becomes more degenerate At high temperatures: >4/3 because the particles become relativistic such that the energy ...
... The decrease of below 4/3 is a consequence of the new particles which do not immediately add their contribution to the total pressure.. At high densities: >4/3, because the electron becomes more degenerate At high temperatures: >4/3 because the particles become relativistic such that the energy ...
Stellar population models in the Near-Infrared Meneses
... different stellar evolution tracers, such as line-strength indices (the relative strength of a spectral absorption line, determined by comparing the spectral flux on both sides of the feature with the flux inside the absorption line), integrated colours and Spectral Energy Distributions (SEDs). By c ...
... different stellar evolution tracers, such as line-strength indices (the relative strength of a spectral absorption line, determined by comparing the spectral flux on both sides of the feature with the flux inside the absorption line), integrated colours and Spectral Energy Distributions (SEDs). By c ...
It is now recognized that the vast majority of ellipticals are of
... • In contrast, E galaxies with close companions often have luminosity profiles which rise above a de Vaucouleurs law at large radii. These features may be plausibly blamed on tidal interactions. • E galaxies in closely interacting systems sometimes exhibit outer isophotes which are visibly eggshaped ...
... • In contrast, E galaxies with close companions often have luminosity profiles which rise above a de Vaucouleurs law at large radii. These features may be plausibly blamed on tidal interactions. • E galaxies in closely interacting systems sometimes exhibit outer isophotes which are visibly eggshaped ...
Powerpoint Presentation (large file)
... neutron stars produce novae and bursters • Material from an ordinary star in a close binary can fall onto the surface of the companion white dwarf or neutron star to produce a surface layer in which thermonuclear reactions can explosively ignite • Explosive hydrogen fusion may occur in the surface l ...
... neutron stars produce novae and bursters • Material from an ordinary star in a close binary can fall onto the surface of the companion white dwarf or neutron star to produce a surface layer in which thermonuclear reactions can explosively ignite • Explosive hydrogen fusion may occur in the surface l ...
Question 1
... The period–luminosity relationship is a crucial component of a) measuring distances with Cepheid variable stars. b) identifying the mass of the Galaxy’s central black hole. c) determining the masses of stars in an eclipsing binary system. d) using spectroscopic parallax to measure distances to stars ...
... The period–luminosity relationship is a crucial component of a) measuring distances with Cepheid variable stars. b) identifying the mass of the Galaxy’s central black hole. c) determining the masses of stars in an eclipsing binary system. d) using spectroscopic parallax to measure distances to stars ...
Cosmology and Particle Physics
... to the observer. Double the distance, and the red shift is doubled. While this cosmological red shift is often called a Doppler shift, it is notspace itself is expanding. There is no center of expansion in the universe. All observers see themselves as stationary; the other objects in space appear t ...
... to the observer. Double the distance, and the red shift is doubled. While this cosmological red shift is often called a Doppler shift, it is notspace itself is expanding. There is no center of expansion in the universe. All observers see themselves as stationary; the other objects in space appear t ...
Chapter 1 Introduction
... Much of astronomy plays out over timescales much longer than a human lifetime. From the gravitational dances of galaxies to the nuclear furnaces powering the stars within them, we typically see these processes as if frozen at a moment in time. Large ensembles of observations, along with the fortune ...
... Much of astronomy plays out over timescales much longer than a human lifetime. From the gravitational dances of galaxies to the nuclear furnaces powering the stars within them, we typically see these processes as if frozen at a moment in time. Large ensembles of observations, along with the fortune ...
pkt 14 Astrophysics
... A supernova causes a burst of radiation that may briefly outshine its entire host galaxy before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun would emit over 10 billion years. ...
... A supernova causes a burst of radiation that may briefly outshine its entire host galaxy before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun would emit over 10 billion years. ...
Our Local Group of Galaxies
... The Sgr dSph has proved to be a very interesting object - has 4, perhaps 6+, globular clusters of its own, and is currently being disrupted by the tidal field of the Galaxy. Sgr stars are spread over a large part of the sky, tracing out the orbit. See Law & Majewski 2010 ApJ 714 229 and refs ...
... The Sgr dSph has proved to be a very interesting object - has 4, perhaps 6+, globular clusters of its own, and is currently being disrupted by the tidal field of the Galaxy. Sgr stars are spread over a large part of the sky, tracing out the orbit. See Law & Majewski 2010 ApJ 714 229 and refs ...
Chapter 13
... 8. Why have no black dwarfs yet been observed in our galaxy? a. They can only be detected by their gravitational influence on a binary companion. b. They are too dim for our present-day telescopes to detect. c. Astronomers are not motivated to search for such objects. d. They are all too distant (in ...
... 8. Why have no black dwarfs yet been observed in our galaxy? a. They can only be detected by their gravitational influence on a binary companion. b. They are too dim for our present-day telescopes to detect. c. Astronomers are not motivated to search for such objects. d. They are all too distant (in ...
Nuclear Synthesis
... • Black holes can keep accumulating mass…including “colliding” Black holes. Very massive (million times mass Sun) at center of many galaxies ...
... • Black holes can keep accumulating mass…including “colliding” Black holes. Very massive (million times mass Sun) at center of many galaxies ...
Gamma-ray burst
Gamma-ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the brightest electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several hours. The initial burst is usually followed by a longer-lived ""afterglow"" emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio).Most observed GRBs are believed to consist of a narrow beam of intense radiation released during a supernova or hypernova as a rapidly rotating, high-mass star collapses to form a neutron star, quark star, or black hole. A subclass of GRBs (the ""short"" bursts) appear to originate from a different process – this may be due to the merger of binary neutron stars. The cause of the precursor burst observed in some of these short events may be due to the development of a resonance between the crust and core of such stars as a result of the massive tidal forces experienced in the seconds leading up to their collision, causing the entire crust of the star to shatter.The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per million years). All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction event.GRBs were first detected in 1967 by the Vela satellites, a series of satellites designed to detect covert nuclear weapons tests. Hundreds of theoretical models were proposed to explain these bursts in the years following their discovery, such as collisions between comets and neutron stars. Little information was available to verify these models until the 1997 detection of the first X-ray and optical afterglows and direct measurement of their redshifts using optical spectroscopy, and thus their distances and energy outputs. These discoveries, and subsequent studies of the galaxies and supernovae associated with the bursts, clarified the distance and luminosity of GRBs. These facts definitively placed them in distant galaxies and also connected long GRBs with the explosion of massive stars, the only possible source for the energy outputs observed.