View/Open - University of Hertfordshire
... universe2 . The Friedmann equations show that at a critical matter density, ρc , the universe will be flat. Modern cosmological measurements [Komatsu et al., 2011, Planck Collaboration et al., 2014b] show that the density of the universe is close to ρc [Coles and Lucchin, 2002]. The difficulty is th ...
... universe2 . The Friedmann equations show that at a critical matter density, ρc , the universe will be flat. Modern cosmological measurements [Komatsu et al., 2011, Planck Collaboration et al., 2014b] show that the density of the universe is close to ρc [Coles and Lucchin, 2002]. The difficulty is th ...
RADIO OBSERVATIONS RELATED TO STAR FORMATION P. G.
... which is four times the intrinsic flux density of Orion A.) Giant HII regions are known to define the main spiral structure in external galaxies. Georgelin and Georgelin (1976) used this fact to determine the spiral structure of our Galaxy on the basis of optical and radio observations of giant HII ...
... which is four times the intrinsic flux density of Orion A.) Giant HII regions are known to define the main spiral structure in external galaxies. Georgelin and Georgelin (1976) used this fact to determine the spiral structure of our Galaxy on the basis of optical and radio observations of giant HII ...
THE DEARTH OF UV-BRIGHT STARS IN M32
... branch (HB) population and other hot stars in late phases of stellar evolution. We find few post-asymptotic giant branch (PAGB) stars in the galaxy, implying that these stars either cross the HR diagram more rapidly than expected, and/or that they spend a significant fraction of their time enshroude ...
... branch (HB) population and other hot stars in late phases of stellar evolution. We find few post-asymptotic giant branch (PAGB) stars in the galaxy, implying that these stars either cross the HR diagram more rapidly than expected, and/or that they spend a significant fraction of their time enshroude ...
Radio Emission Toward Regions of Massive Star Formation
... Our understanding of high-mass star formation is not that simple. In this dissertation and per convention, stars with enough mass to end their lives as core-collapse supernovae (M∗ ≥ 8.0 M ) are considered ‘high-mass’ stars. High-mass stars have difficulty forming in this fashion, because the onset ...
... Our understanding of high-mass star formation is not that simple. In this dissertation and per convention, stars with enough mass to end their lives as core-collapse supernovae (M∗ ≥ 8.0 M ) are considered ‘high-mass’ stars. High-mass stars have difficulty forming in this fashion, because the onset ...
DEDUCING THE LIFETIME OF SHORT GAMMA
... Christensen et al. 2004), these observations clearly signify that, like Type Ia supernovae, short GRBs are triggered in galaxies of all types. What is more, it indicates that there is a time delay between short burst occurrence and the main epoch of star formation activity in the hosts, as determine ...
... Christensen et al. 2004), these observations clearly signify that, like Type Ia supernovae, short GRBs are triggered in galaxies of all types. What is more, it indicates that there is a time delay between short burst occurrence and the main epoch of star formation activity in the hosts, as determine ...
REVIEW Early star-forming galaxies and the reionization of the Universe
... Observations of distant quasars3 demonstrate that the IGM has been highly ionized since the Universe was ,1 billion years (Gyr) old, and the transition from a neutral medium is popularly interpreted as being caused by ionizing photons with energies greater than 13.6 eV (wavelength, l , 91.2 nm), gen ...
... Observations of distant quasars3 demonstrate that the IGM has been highly ionized since the Universe was ,1 billion years (Gyr) old, and the transition from a neutral medium is popularly interpreted as being caused by ionizing photons with energies greater than 13.6 eV (wavelength, l , 91.2 nm), gen ...
Modelling galaxy spectra in presence of interstellar dust – II. From
... ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main components: (i) the diffuse interstellar medium (ISM) composed of gas and dust, (ii) the large complexes of molecular clouds (MCs) in which new stars are formed and (iii) the stars of any age and ...
... ultraviolet–optical (UV–optical) light and re-emitting it in the infrared. The models contain three main components: (i) the diffuse interstellar medium (ISM) composed of gas and dust, (ii) the large complexes of molecular clouds (MCs) in which new stars are formed and (iii) the stars of any age and ...
Gravitationally lensed galaxies at 2 z 3.5: direct abundance
... λ5755 which, when related to other transitions from the same ionization stage, are sensitive to the gas temperature. Combining this with the knowledge of the density of the gas, it is possible to derive the abundances of various chemical elements directly (Osterbrock 1989). This approach is widely u ...
... λ5755 which, when related to other transitions from the same ionization stage, are sensitive to the gas temperature. Combining this with the knowledge of the density of the gas, it is possible to derive the abundances of various chemical elements directly (Osterbrock 1989). This approach is widely u ...
radioactive 26a1 in the galaxy: observations versus theory
... Nuclear Astrophysics emerged in the 40ies from the marriage of the old science of astronomy with the young discipline of nuclear physics. The purpose of this marriage was, essentially, twofold: to understand the energetics of stars in their various evolutionary stages and to explain the origin of th ...
... Nuclear Astrophysics emerged in the 40ies from the marriage of the old science of astronomy with the young discipline of nuclear physics. The purpose of this marriage was, essentially, twofold: to understand the energetics of stars in their various evolutionary stages and to explain the origin of th ...
Dust-free quasars in the early Universe
... evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them. More than 40 quasars have been discovered at redshift ...
... evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them. More than 40 quasars have been discovered at redshift ...
Research paper
... −100 to +120 km s−1 ; Figure 3 shows a moment 0 image over the same radial velocity range. Figure 4 shows a color version of the maximum temperature from VLSR = −100 to 0 km s−1 in blue and from VLSR = 20 to 120 km s−1 in red. The maximum brightness temperature better illustrates the relatively cons ...
... −100 to +120 km s−1 ; Figure 3 shows a moment 0 image over the same radial velocity range. Figure 4 shows a color version of the maximum temperature from VLSR = −100 to 0 km s−1 in blue and from VLSR = 20 to 120 km s−1 in red. The maximum brightness temperature better illustrates the relatively cons ...
Extragalactic Astronomical Masers I
... most likely to originate from starforming activity in host galaxies. On the other hand, the sub-population of H2O masers with 1 Lʘ < Liso < 10 Lʘ is known, most of them are considered to arise in starforming sites in galaxies, while some are in AGN like megamasers. The main reason of the low-luminos ...
... most likely to originate from starforming activity in host galaxies. On the other hand, the sub-population of H2O masers with 1 Lʘ < Liso < 10 Lʘ is known, most of them are considered to arise in starforming sites in galaxies, while some are in AGN like megamasers. The main reason of the low-luminos ...
A SPECTROSCOPIC STUDY OF A LARGE SAMPLE OF WOLF-RAYET GALAXIES
... hence cannot be distinguished from other WR stars in low-resolution spectra. Additionally, WNE stars are not as luminous as WNL stars in the optical range. The WR star lifetime in the WNE stage is short compared to that in the WNL stage for nearly all metallicities and progenitor star masses (Maeder ...
... hence cannot be distinguished from other WR stars in low-resolution spectra. Additionally, WNE stars are not as luminous as WNL stars in the optical range. The WR star lifetime in the WNE stage is short compared to that in the WNL stage for nearly all metallicities and progenitor star masses (Maeder ...
3 science case - Giant Magellan Telescope Organization
... giants. Observations at 3-5 micron wavelengths provide the largest contrast between the planet and star. Thus, high spatial resolution IR imaging and high spectral resolution IR spectroscopy enable the highest quality probes of the physical properties of gas giant planets. Nearby field stars, stell ...
... giants. Observations at 3-5 micron wavelengths provide the largest contrast between the planet and star. Thus, high spatial resolution IR imaging and high spectral resolution IR spectroscopy enable the highest quality probes of the physical properties of gas giant planets. Nearby field stars, stell ...
HI in Early-type Galaxies
... galaxies is quite large, but it appears that there are a few systematic trends in the data, and in particular that some of the HI properties may be connected to properties observed at other wavebands. Many low-luminosity early-type galaxies that have HI, have this HI in a regularly rotating disk. In ...
... galaxies is quite large, but it appears that there are a few systematic trends in the data, and in particular that some of the HI properties may be connected to properties observed at other wavebands. Many low-luminosity early-type galaxies that have HI, have this HI in a regularly rotating disk. In ...
AVS03ML - Brigham Young University
... The rainbow falls on a pinhole so that only one wavelength passes through. ...
... The rainbow falls on a pinhole so that only one wavelength passes through. ...
Study properties of dwarf galaxies in and around the nearby Lynx
... The galaxy evolution versus the global environment (clusters, groups, voids) is a long-studied problem. Voids are delineated by luminous (L > L*) massive objects and populated by dwarfs. The galaxy densities and other parameters vary significantly from one void to another. One expects that not only ...
... The galaxy evolution versus the global environment (clusters, groups, voids) is a long-studied problem. Voids are delineated by luminous (L > L*) massive objects and populated by dwarfs. The galaxy densities and other parameters vary significantly from one void to another. One expects that not only ...
UvA-DARE (Digital Academic Repository) Multi
... the first optical afterglow (Van Paradijs et al. 1997). This breakthrough was followed a few months later when the afterglow of GRB 970508 was also detected at the other end of the electromagnetic spectrum, in radio (Frail et al. 1997). The sub-arcsecond positions of X-ray and optical identification ...
... the first optical afterglow (Van Paradijs et al. 1997). This breakthrough was followed a few months later when the afterglow of GRB 970508 was also detected at the other end of the electromagnetic spectrum, in radio (Frail et al. 1997). The sub-arcsecond positions of X-ray and optical identification ...
observations and theory of star cluster formation
... Vogelaar and Wakker 1994). This power law structure includes both gas that is self-gravitating and gas that is non-self-gravitating, so the origin is not purely gravitational fragmentation. The most likely source is some combination of turbulence (see review in Falgarone and Phillips 1991), agglomer ...
... Vogelaar and Wakker 1994). This power law structure includes both gas that is self-gravitating and gas that is non-self-gravitating, so the origin is not purely gravitational fragmentation. The most likely source is some combination of turbulence (see review in Falgarone and Phillips 1991), agglomer ...
original version
... interacting and merging galaxies (Classes C, B and A) form stars at a lower rate than might be expected from their mass and type. We thus see that many interacting galaxies have no enhanced (S)SFR at all. 3.3. Interactions Do Increase the (S)SFR, but Not by Much The median SFR and SSFR enhancement v ...
... interacting and merging galaxies (Classes C, B and A) form stars at a lower rate than might be expected from their mass and type. We thus see that many interacting galaxies have no enhanced (S)SFR at all. 3.3. Interactions Do Increase the (S)SFR, but Not by Much The median SFR and SSFR enhancement v ...
Anisotropy of the Hectometer Cosmic Radio Background
... a 0.1 degree and the spacecraft rotation period. By way of illustration, Fig. 1 shows oscillograms of the signals from the S-antenna output in the December 27, 1997 session. When RAD1 is switched from the standard mode (the beginning and end of the records correspond to this mode) to the mode of sca ...
... a 0.1 degree and the spacecraft rotation period. By way of illustration, Fig. 1 shows oscillograms of the signals from the S-antenna output in the December 27, 1997 session. When RAD1 is switched from the standard mode (the beginning and end of the records correspond to this mode) to the mode of sca ...
Triggered/sequential star formation? A multi
... survey provides information on the atomic hydrogen gas. Results. We show that the bubble is spatially associated with G18.93, located at a kinematic near distance of 3.6 kpc. The total gas mass of ∼870 M splits up into 6 sub-clumps, of which G18.93/m is the most massive with 280 M . The virial ana ...
... survey provides information on the atomic hydrogen gas. Results. We show that the bubble is spatially associated with G18.93, located at a kinematic near distance of 3.6 kpc. The total gas mass of ∼870 M splits up into 6 sub-clumps, of which G18.93/m is the most massive with 280 M . The virial ana ...
Monitoring orbital period variations in eclipsing white dwarf binaries
... Combining precise ULTRACAM eclipse times with regular LT+RISE data enables us to detect any period variations in a large number of eclipsing white dwarf binaries. Most of the well enough studied binaries show some sort of variation in their orbital periods. If Applegate’s mechanism is the dominant c ...
... Combining precise ULTRACAM eclipse times with regular LT+RISE data enables us to detect any period variations in a large number of eclipsing white dwarf binaries. Most of the well enough studied binaries show some sort of variation in their orbital periods. If Applegate’s mechanism is the dominant c ...
Corrugations in the Disk of the Edge
... The arrows on the upper left panel of Figure 1 indicate the extent of the stellar disk of IC 2233, as determined from the 25 magnitude arcsec−2 B-band isophote. It can be seen that near the edge of the stellar disk, the H i layer twists to form an “integral sign” warp. On the side of the disk where ...
... The arrows on the upper left panel of Figure 1 indicate the extent of the stellar disk of IC 2233, as determined from the 25 magnitude arcsec−2 B-band isophote. It can be seen that near the edge of the stellar disk, the H i layer twists to form an “integral sign” warp. On the side of the disk where ...
Spin frequency distributions of binary millisecond pulsars
... D. R. Lorimer2 and P. C. C. Freire3 , corresponding to sources found in the Galactic field and globular clusters, respectively. As of January 2014, these lists contain 339 radio pulsars with a spin period shorter than 30 ms. Slightly fewer than half of them are isolated sources, or systems for which ...
... D. R. Lorimer2 and P. C. C. Freire3 , corresponding to sources found in the Galactic field and globular clusters, respectively. As of January 2014, these lists contain 339 radio pulsars with a spin period shorter than 30 ms. Slightly fewer than half of them are isolated sources, or systems for which ...
Astrophysical X-ray source
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays.There are a number of types of astrophysical objects which emit X-rays, from galaxy clusters, through black holes in active galactic nuclei (AGN) to galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf (cataclysmic variable stars and super soft X-ray sources), neutron star or black hole (X-ray binaries). Some solar system bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background. The X-ray continuum can arise from bremsstrahlung, either magnetic or ordinary Coulomb, black-body radiation, synchrotron radiation, inverse Compton scattering of lower-energy photons be relativistic electrons, knock-on collisions of fast protons with atomic electrons, and atomic recombination, with or without additional electron transitions.Furthermore, celestial entities in space are discussed as celestial X-ray sources. The origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period.