PH607lec08
... • Few E galaxies actually have flat luminosity profiles at small radii; instead, the profiles rise inward to the last measured point . • Cores may exhibit unusual kinematics; for example, about a quarter of all elliptical galaxies have cores which appear to counter-rotate with respect to the rest of ...
... • Few E galaxies actually have flat luminosity profiles at small radii; instead, the profiles rise inward to the last measured point . • Cores may exhibit unusual kinematics; for example, about a quarter of all elliptical galaxies have cores which appear to counter-rotate with respect to the rest of ...
Ch 33) Astrophysics and Cosmology
... NOTE In terms of numbers of stars, if they are like our Sun Am = 2.0 * 1030 kgB, there would be about A2 * 1041 kgB兾A2 * 1030 kgB L 1011 or very roughly on the order of 100 billion stars. SECTION 33–1 ...
... NOTE In terms of numbers of stars, if they are like our Sun Am = 2.0 * 1030 kgB, there would be about A2 * 1041 kgB兾A2 * 1030 kgB L 1011 or very roughly on the order of 100 billion stars. SECTION 33–1 ...
STELLAR AGE VERSUS MASS OF EARLY
... realistic population – with a finite duration of star formation rather than a delta-peak – can never become so red, since not all of its stars reach this period at the same time. Indeed, the model population that formed from a single burst of finite length lies within the observed color range, altho ...
... realistic population – with a finite duration of star formation rather than a delta-peak – can never become so red, since not all of its stars reach this period at the same time. Indeed, the model population that formed from a single burst of finite length lies within the observed color range, altho ...
Annual Report 2006/2007
... when the Universe was less than 5% of its present age. The theme of the NOVA Program is to unravel the history of the universe and to further develop the understanding of the life cycle of stars and galaxies. The NOVA research program concentrates on the following three interconnected areas: • Netw ...
... when the Universe was less than 5% of its present age. The theme of the NOVA Program is to unravel the history of the universe and to further develop the understanding of the life cycle of stars and galaxies. The NOVA research program concentrates on the following three interconnected areas: • Netw ...
IXO as an observatory in the large telescopes era
... It must also be borne in mind that luminous, optical QSOs, hosting among the most massive black holes (>109 M) in the Universe, are extremely rare. Typical AGN, which are of lower luminosity and often obscured, remain largely undiscovered. Uncovering such objects at z=6-7 (and even higher redshifts ...
... It must also be borne in mind that luminous, optical QSOs, hosting among the most massive black holes (>109 M) in the Universe, are extremely rare. Typical AGN, which are of lower luminosity and often obscured, remain largely undiscovered. Uncovering such objects at z=6-7 (and even higher redshifts ...
GALEX and Star Formation
... Massive stars drive the chemical evolution of the Universe, enriching the interstellar medium (ISM) with nucleosynthesis products via supenova explosions and intense mass loss during AGB and planetary nebula phases, and driving the dynamical evolution of the ISM through highly supersonic stellar win ...
... Massive stars drive the chemical evolution of the Universe, enriching the interstellar medium (ISM) with nucleosynthesis products via supenova explosions and intense mass loss during AGB and planetary nebula phases, and driving the dynamical evolution of the ISM through highly supersonic stellar win ...
The Scuti star XX Pyx is an ellipsoidal variable
... abundance values. We show that an increase in the relative number fraction of iron throughout the whole star or a large decrease in the initial hydrogen abundance make the stellar models matching the four selected modes satisfy all observational constraints and we provide the general properties of ...
... abundance values. We show that an increase in the relative number fraction of iron throughout the whole star or a large decrease in the initial hydrogen abundance make the stellar models matching the four selected modes satisfy all observational constraints and we provide the general properties of ...
Discoveries with the Green Bank Telescope
... Stars form in clusters in the densest parts of molecular clouds under conditions that are still uncertain. The GBT is a superb instrument for studying this process on a variety of angular scales in the Milky Way and other galaxies as well. Mapping clouds in multiple molecular species reveals the ove ...
... Stars form in clusters in the densest parts of molecular clouds under conditions that are still uncertain. The GBT is a superb instrument for studying this process on a variety of angular scales in the Milky Way and other galaxies as well. Mapping clouds in multiple molecular species reveals the ove ...
Annual report 2004 - Département d`Astrophysique, Géophysique et
... In the framework of a long-term spectroscopic and photometric monitoring of slowly pulsating B stars we studied thoroughly the northern target star HD 147394. We performed an end-to-end analysis, consisting of a frequency analysis, a mode identification from line-profile variations and a comparison ...
... In the framework of a long-term spectroscopic and photometric monitoring of slowly pulsating B stars we studied thoroughly the northern target star HD 147394. We performed an end-to-end analysis, consisting of a frequency analysis, a mode identification from line-profile variations and a comparison ...
Galaxies
... mutual gravity cannot hold them together is called a. a globular cluster. b. an open cluster. c. an association. d. a spherical component e. an accretion disk. 4. Our galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy a. rotates faster than expected in its outer ...
... mutual gravity cannot hold them together is called a. a globular cluster. b. an open cluster. c. an association. d. a spherical component e. an accretion disk. 4. Our galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy a. rotates faster than expected in its outer ...
Nebula
... A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. The name originates from a similarity in appearance to giant planets when viewed through a small optical telescope and is unrelated to planets of t ...
... A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. The name originates from a similarity in appearance to giant planets when viewed through a small optical telescope and is unrelated to planets of t ...
Recen t Scien ti c
... incorrectly classied. For example, these may actually be symbiotic stars with neutron star companions (similar to the galactic source GX 1+4). Future optical spectroscopy may help resolve this puzzle. There is unresolved emission in the central region of M31 that is easily seen near the center of t ...
... incorrectly classied. For example, these may actually be symbiotic stars with neutron star companions (similar to the galactic source GX 1+4). Future optical spectroscopy may help resolve this puzzle. There is unresolved emission in the central region of M31 that is easily seen near the center of t ...
On the nature and detectability of Type Ib/c supernova progenitors
... Context. The progenitors of many Type II supernovae have been observationally identified but the search for Type Ibc supernova (SN Ibc) progenitors has thus far been unsuccessful, despite the expectation that they are luminous Wolf-Rayet (WR) stars. Aims. We investigate how the evolution of massive ...
... Context. The progenitors of many Type II supernovae have been observationally identified but the search for Type Ibc supernova (SN Ibc) progenitors has thus far been unsuccessful, despite the expectation that they are luminous Wolf-Rayet (WR) stars. Aims. We investigate how the evolution of massive ...
Lecture 9: The interstellar medium (ISM)
... strengths of IS absorption lines. There is no correlation of depletion factor with atomic weight A, but a good correlation with the element’s condensation temperature Tc. ...
... strengths of IS absorption lines. There is no correlation of depletion factor with atomic weight A, but a good correlation with the element’s condensation temperature Tc. ...
Annual report 2002 - Département d`Astrophysique, Géophysique et
... variations. The photometric amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived earlier from the line profiles. Additional periods of low-amplitude modes (between 0.2-0.3 mmag) are also derived, including one s ...
... variations. The photometric amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived earlier from the line profiles. Additional periods of low-amplitude modes (between 0.2-0.3 mmag) are also derived, including one s ...
The accretion disk paradigm for young stars
... as data started to accumulate, these promising physical findings were clouded by what appeared to be contradictory observations, and it took 40 years to disentangle the various issues and understand “the nature of the objects of Joy”†. What was less evident in the late 1940s and early 1950s was the e ...
... as data started to accumulate, these promising physical findings were clouded by what appeared to be contradictory observations, and it took 40 years to disentangle the various issues and understand “the nature of the objects of Joy”†. What was less evident in the late 1940s and early 1950s was the e ...
Description of Pictures In the Dome
... The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years and is the closest region of massive star for ...
... The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years and is the closest region of massive star for ...
19_Testbank - Lick Observatory
... B) We cannot see the galactic center with visible or ultraviolet light, but radio and X rays from the center can be detected. C) The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there. D) We ...
... B) We cannot see the galactic center with visible or ultraviolet light, but radio and X rays from the center can be detected. C) The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there. D) We ...
VLT identifications in the Chandra/XMM
... sion lines and high-excitation lines indicating photoionization by a hard continuum source. However, already in the spectroscopic identifications of the ROSAT Deep Surveys it became apparent, that an increasing fraction of faint X-ray selected AGN shows a significant, sometimes dominant contribution ...
... sion lines and high-excitation lines indicating photoionization by a hard continuum source. However, already in the spectroscopic identifications of the ROSAT Deep Surveys it became apparent, that an increasing fraction of faint X-ray selected AGN shows a significant, sometimes dominant contribution ...
Option D – Astrophysics
... The solar system The Sun and all the objects orbiting it are collectively known as the solar system. Our Sun is a star and it is very similar to billions of other stars in the universe. It has many objects orbiting around it that are held in their orbits by gravity. The solar system is an example of ...
... The solar system The Sun and all the objects orbiting it are collectively known as the solar system. Our Sun is a star and it is very similar to billions of other stars in the universe. It has many objects orbiting around it that are held in their orbits by gravity. The solar system is an example of ...
Document
... A majority of the galaxies in rich clusters are ellipticals, not spirals. There is often a single, very large central elliptical galaxy (sometimes two) that is cannibalizing other galaxies in its vicinity, growing bigger with time (see figure, top). X-ray observations of rich clusters reveal a hot i ...
... A majority of the galaxies in rich clusters are ellipticals, not spirals. There is often a single, very large central elliptical galaxy (sometimes two) that is cannibalizing other galaxies in its vicinity, growing bigger with time (see figure, top). X-ray observations of rich clusters reveal a hot i ...
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.