The Milky Way-Pulsars and Isolated Neutron Stars
... Cygnus region and the first evidence for the existence of a diffuse isotropic X-ray background was also reported from that experiment (Giacconi et al. 1962). Subsequent flights launched to confirm these first results detected Tau X-1, a source in the constellation Taurus which coincided with the Cra ...
... Cygnus region and the first evidence for the existence of a diffuse isotropic X-ray background was also reported from that experiment (Giacconi et al. 1962). Subsequent flights launched to confirm these first results detected Tau X-1, a source in the constellation Taurus which coincided with the Cra ...
T Tauri stars Optical lucky imaging polarimetry of HL and XZ Tau
... place and creates complex molecules. The enormous density contrast between typical cloud densities and the hydrogen-burning centres of the final stars is typically about 24 orders of magnitude. The following is a description of the current star formation paradigm, which applies to low- and possibly ...
... place and creates complex molecules. The enormous density contrast between typical cloud densities and the hydrogen-burning centres of the final stars is typically about 24 orders of magnitude. The following is a description of the current star formation paradigm, which applies to low- and possibly ...
Photometric catalog of nearby globular clusters
... et al. 2000). We present the first CCD color magnitude diagram for NGC 6779 (M 56). All the CMDs extend from at least ∼ 2 magnitudes below the turn-off (i.e. Vlim ≥ 22) to the tip of the red giant branch. The calibration has been done using a large number of standard stars, and the absolute calibrat ...
... et al. 2000). We present the first CCD color magnitude diagram for NGC 6779 (M 56). All the CMDs extend from at least ∼ 2 magnitudes below the turn-off (i.e. Vlim ≥ 22) to the tip of the red giant branch. The calibration has been done using a large number of standard stars, and the absolute calibrat ...
The asymmetric nuclear region of M83 and its off
... The barred spiral galaxy M83 is one of the closest galaxies hosting a nuclear starburst. It is almost face-on (i=24◦ Comte 1981), and at a distance of 4.5 Mpc (Thim et al. 2003) it allows excellent spatial resolution (1′′ =22 pc) over the active region. The nuclear region has been studied in detail ...
... The barred spiral galaxy M83 is one of the closest galaxies hosting a nuclear starburst. It is almost face-on (i=24◦ Comte 1981), and at a distance of 4.5 Mpc (Thim et al. 2003) it allows excellent spatial resolution (1′′ =22 pc) over the active region. The nuclear region has been studied in detail ...
The colour–magnitude relation of globular clusters in Centaurus and
... equivalent to a scaling with mass of Z ∝ M 0.3−0.7 , that depends on environment. Results have so far indicated that the trend sets in already at masses slightly below a million solar masses, at several 105 M . The most common interpretation of this colour-metallicity relation is self-enrichment. W ...
... equivalent to a scaling with mass of Z ∝ M 0.3−0.7 , that depends on environment. Results have so far indicated that the trend sets in already at masses slightly below a million solar masses, at several 105 M . The most common interpretation of this colour-metallicity relation is self-enrichment. W ...
Observation of Circumstellar Disks: Dust and Gas Components
... that binarity strongly affects the dust and gas distribution as a result of tidal truncations. The material can be in a circumbinary ring as in the GG Tau disk (Dutrey et al., 1994) or confined in small, truncated, circumstellar disks. However, for simplicity, we will focus here on properties of dis ...
... that binarity strongly affects the dust and gas distribution as a result of tidal truncations. The material can be in a circumbinary ring as in the GG Tau disk (Dutrey et al., 1994) or confined in small, truncated, circumstellar disks. However, for simplicity, we will focus here on properties of dis ...
The extinction map of the OMC-1 molecular cloud behind the Orion
... still the only one covering the entire ONC field. However, its spatial resolution (6 ) is limited and the accuracy, in a region as complex as the OMC-1, remains questionable. In Sect. 3 we overcome most of the issues listed above using photometric data in the NIR bands, as they offer several well kn ...
... still the only one covering the entire ONC field. However, its spatial resolution (6 ) is limited and the accuracy, in a region as complex as the OMC-1, remains questionable. In Sect. 3 we overcome most of the issues listed above using photometric data in the NIR bands, as they offer several well kn ...
SUPERNOVA REMNANT SHOCKS IN AN INHOMOGENEOUS
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
... (McKee and Ostriker 1977). Although fh is high in the local ISM, its value at a typical point in the galactic disk remains controversial (Cox 1987). It is quite likely that fh depends on both the nature of the galaxy and the location within it. In principle, observations of SNRs could provide the me ...
150 Million ly - Northern Michigan University
... During the years from 1758 to 1782 Charles Messier, a French astronomer (1730 - 1817), compiled a list of approximately 100 diffuse objects that were difficult to distinguish from comets through the telescopes of the day. Discovering comets was the way to make a name for yourself in astronomy in the ...
... During the years from 1758 to 1782 Charles Messier, a French astronomer (1730 - 1817), compiled a list of approximately 100 diffuse objects that were difficult to distinguish from comets through the telescopes of the day. Discovering comets was the way to make a name for yourself in astronomy in the ...
View/Open - University of Hertfordshire
... Albada et al. [1985] and others. These studies show that the kinematics of objects, under Newtonian gravitational theory, cannot be fully accounted for by the mass of observed luminous matter in the universe, and additional matter must be added. While it is unlikely that all baryonic matter has been ...
... Albada et al. [1985] and others. These studies show that the kinematics of objects, under Newtonian gravitational theory, cannot be fully accounted for by the mass of observed luminous matter in the universe, and additional matter must be added. While it is unlikely that all baryonic matter has been ...
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 ...
Celestial Object Imaging Model and Parameter Optimization for an
... New image sensor designs are also proposed to attain an extended dynamic range. The photocurrent in logarithmic response image sensors is fed to a resistor with a logarithmic current-voltage characteristic [8–10]. Logarithmic-response image sensors can obtain a wide dynamic range, but it has several ...
... New image sensor designs are also proposed to attain an extended dynamic range. The photocurrent in logarithmic response image sensors is fed to a resistor with a logarithmic current-voltage characteristic [8–10]. Logarithmic-response image sensors can obtain a wide dynamic range, but it has several ...
The close circumstellar environment of Betelgeuse
... stars, among which the structure of their convection, the mechanism of their mass loss (Levesque 2010) and the way dust forms in their environment (Verhoelst et al. 2009). Josselin et al. (2000) showed that the dust mass-loss rate is not correlated with luminosity, and that the molecular gas-to-dust ...
... stars, among which the structure of their convection, the mechanism of their mass loss (Levesque 2010) and the way dust forms in their environment (Verhoelst et al. 2009). Josselin et al. (2000) showed that the dust mass-loss rate is not correlated with luminosity, and that the molecular gas-to-dust ...
Binocular Certificate Handbook
... If you have seen a picture of a total eclipse of the Sun you will have noticed that the black disk of the Moon just about covers the bright disk of The Sun. The Sun is 1·6 million km in diameter and the Moon is 3200 km. Yet they appear nearly equal. This is because they seem to take up the same amou ...
... If you have seen a picture of a total eclipse of the Sun you will have noticed that the black disk of the Moon just about covers the bright disk of The Sun. The Sun is 1·6 million km in diameter and the Moon is 3200 km. Yet they appear nearly equal. This is because they seem to take up the same amou ...
SNEWS - University of Minnesota
... SN Galore • Luminosity of a galaxy from one star for a few weeks – Visible across most of the universe – Ia are Standard Bombs used in cosmological work – These days the “year + letter” naming scheme is getting cumbersome, almost need to bar code the things ...
... SN Galore • Luminosity of a galaxy from one star for a few weeks – Visible across most of the universe – Ia are Standard Bombs used in cosmological work – These days the “year + letter” naming scheme is getting cumbersome, almost need to bar code the things ...
evolución química de la nube grande de magallanes.
... Taking this last scenario into account, plus the intriguing star cluster population and what little is known of the chemical evolution of our galaxy neighbour, the Large Magellanic Cloud(LMC), it was decided to proceed with a study of this galaxy based on three clear aims. First, to chemically const ...
... Taking this last scenario into account, plus the intriguing star cluster population and what little is known of the chemical evolution of our galaxy neighbour, the Large Magellanic Cloud(LMC), it was decided to proceed with a study of this galaxy based on three clear aims. First, to chemically const ...
Stellar activity in exoplanet hosts Enrique Herrero Casas
... period of 12.718 days, apart from photometric oscillations with the same periodicity and a phase lag of ∼ 100◦ from the eclipses, persisting for more than 500 days. The accurate modelling of the Kepler data allowed to explain these oscillations with the presence of active regions appearing at a spec ...
... period of 12.718 days, apart from photometric oscillations with the same periodicity and a phase lag of ∼ 100◦ from the eclipses, persisting for more than 500 days. The accurate modelling of the Kepler data allowed to explain these oscillations with the presence of active regions appearing at a spec ...
The Properties of Super Star Clusters in A Sample of
... Color image of HCG 31 constructed using the narrow-band H and continuum images from the WIYN telescope. A blue-green color is indicative of continuum emission, while a red-orange color is representative of H emission. North and east are indicated on the image, with north having the arrowhead. . . . ...
... Color image of HCG 31 constructed using the narrow-band H and continuum images from the WIYN telescope. A blue-green color is indicative of continuum emission, while a red-orange color is representative of H emission. North and east are indicated on the image, with north having the arrowhead. . . . ...
Early Star-Forming Galaxies and the Reionisation of the Universe
... forming galaxies is the Lyman α emission line at rest wavelength of 121.6nm, produced internally by gas heated by young stars. The observability of Lyman α emission is sensitive to the ionisation state of the IGM, as the observed line strength can be attenuated by intervening neutral hydrogen. The ...
... forming galaxies is the Lyman α emission line at rest wavelength of 121.6nm, produced internally by gas heated by young stars. The observability of Lyman α emission is sensitive to the ionisation state of the IGM, as the observed line strength can be attenuated by intervening neutral hydrogen. The ...
Investigating the Spectral Energy Distribution TARA JILL PARKIN
... photons. All stars enrich the ISM with their ejecta through this feedback effect, and impact how a galaxy evolves. Material (i.e. gas and dust) from the outer layers of evolved stars mixes with the contents of the ISM already present, changing the chemical make-up of the ISM over time. The abundance ...
... photons. All stars enrich the ISM with their ejecta through this feedback effect, and impact how a galaxy evolves. Material (i.e. gas and dust) from the outer layers of evolved stars mixes with the contents of the ISM already present, changing the chemical make-up of the ISM over time. The abundance ...
The white dwarf luminosity function
... the age, structure and evolution of our Galaxy but it also provides an independent test of the theory of dense plasmas (Isern et al., 1997, 1998a). Also, it directly constrains the current death rate of low- and intermediate-mass stars in the local neighborhood which, in turn, provides an important ...
... the age, structure and evolution of our Galaxy but it also provides an independent test of the theory of dense plasmas (Isern et al., 1997, 1998a). Also, it directly constrains the current death rate of low- and intermediate-mass stars in the local neighborhood which, in turn, provides an important ...
The effect of helium sedimentation on galaxy cluster masses and
... Sunyaev-Zel’dovich effect (SZE) may be used to infer the helium abundance in the ICM (Markevitch 2007); however, the limited resolution and sensitivity of current SZE interferometers have so far not enabled the measurement of the distribution of helium, even in the cluster cores where the sedimentati ...
... Sunyaev-Zel’dovich effect (SZE) may be used to infer the helium abundance in the ICM (Markevitch 2007); however, the limited resolution and sensitivity of current SZE interferometers have so far not enabled the measurement of the distribution of helium, even in the cluster cores where the sedimentati ...
A large-scale CO survey of the Rosette Molecular Cloud: assessing
... lines. The image also shows that many of the clumps and clouds are limb brightening on their edge facing the O stars. By consideration of the full data cube, we identify three distinct spatiovelocity structures: (1) relatively compact regions with broad line wings, identified as compact or well-coll ...
... lines. The image also shows that many of the clumps and clouds are limb brightening on their edge facing the O stars. By consideration of the full data cube, we identify three distinct spatiovelocity structures: (1) relatively compact regions with broad line wings, identified as compact or well-coll ...
The ATLAS3D Project – XXX. Star formation histories and stellar
... Filled symbols denote the galaxies where Fe5270 could be measured within the given aperture size, with the remainder plotted as open symbols. As found by numerous other authors (e.g. Trager et al. 2000; Thomas et al. 2005), there are rather tight, positive correlations between the metal-sensitive li ...
... Filled symbols denote the galaxies where Fe5270 could be measured within the given aperture size, with the remainder plotted as open symbols. As found by numerous other authors (e.g. Trager et al. 2000; Thomas et al. 2005), there are rather tight, positive correlations between the metal-sensitive li ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.