a changing cosmos - Whittier Union High School District
... A supernova is an unimaginably powerful explosive event. It occurs when a very large star, over eight times the Sun's mass, has burned most of its nuclear fuel. When such a star's central fires go out, its core collapses releasing a huge amount of gravitational energy. A blast wave ejects the star's ...
... A supernova is an unimaginably powerful explosive event. It occurs when a very large star, over eight times the Sun's mass, has burned most of its nuclear fuel. When such a star's central fires go out, its core collapses releasing a huge amount of gravitational energy. A blast wave ejects the star's ...
Joint formation of QSOs and spheroids: QSOs as clocks of star
... (Jablonka, Martin & Arimoto 1996). These facts support the conclusion that spheroids formed stars very rapidly at early epochs (see, e.g., Renzini 1999). The rapid star formation can be strongly reduced or halted by the exhaustion of the gas in most massive objects, or by heating and winds, if SN ex ...
... (Jablonka, Martin & Arimoto 1996). These facts support the conclusion that spheroids formed stars very rapidly at early epochs (see, e.g., Renzini 1999). The rapid star formation can be strongly reduced or halted by the exhaustion of the gas in most massive objects, or by heating and winds, if SN ex ...
The Chemical Composition of Exoplanet
... A significant portion of stars occur as binary systems, in which two stellar components orbit a common center of mass. As the number of known exoplanet systems continues to grow, some binary systems are now known to harbor planets around one or both stellar components. As a first look into compositi ...
... A significant portion of stars occur as binary systems, in which two stellar components orbit a common center of mass. As the number of known exoplanet systems continues to grow, some binary systems are now known to harbor planets around one or both stellar components. As a first look into compositi ...
Type Ia Supernovae
... the core of a massive star. The observationally motivated classes Type II, Type Ib and Type Ic have been attributed to these events. This thesis, however is dedicated to the second group of supernovae, the thermonuclear explosions of degenerate carbon and oxygen rich material and lacking hydrogen - ...
... the core of a massive star. The observationally motivated classes Type II, Type Ib and Type Ic have been attributed to these events. This thesis, however is dedicated to the second group of supernovae, the thermonuclear explosions of degenerate carbon and oxygen rich material and lacking hydrogen - ...
Type Ia supernovae as stellar endpoints and cosmological tools
... without hydrogen or helium in their spectra, but with strong ionized silicon (SiII), which has observed absorption lines at 6,150, 5,800 and 4,000 Å (ref. 4). The progenitor of a Type Ia supernova has never been seen, but the consensus is that they are the result of the thermonuclear explosion of a ...
... without hydrogen or helium in their spectra, but with strong ionized silicon (SiII), which has observed absorption lines at 6,150, 5,800 and 4,000 Å (ref. 4). The progenitor of a Type Ia supernova has never been seen, but the consensus is that they are the result of the thermonuclear explosion of a ...
A Novel Test of the Modified Newtonian Dynamics with Gas Rich
... One striking fact about extragalactic systems is that they are many orders of magnitude larger than the solar system in which conventional dynamics is extraordinarily well tested. One idea is thus to modify gravity on some suitably large length scale such that the apparent need for dark matter would ...
... One striking fact about extragalactic systems is that they are many orders of magnitude larger than the solar system in which conventional dynamics is extraordinarily well tested. One idea is thus to modify gravity on some suitably large length scale such that the apparent need for dark matter would ...
XRaySNR_sm - Gettysburg College
... default for the student, and should not be made available to them. In reality, multiobject spectroscopy is not possible with XMM-Newton. This feature is included simply as an aid to the instructor. To enable it, in the Spectra tab under Options/Multi-Object Spectrometer, click either “Enable after 1 ...
... default for the student, and should not be made available to them. In reality, multiobject spectroscopy is not possible with XMM-Newton. This feature is included simply as an aid to the instructor. To enable it, in the Spectra tab under Options/Multi-Object Spectrometer, click either “Enable after 1 ...
Masses, Radii, and Equation of State of Neutron Stars
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
... We now know precise masses for ∼ 35 neutron stars spanning the range from 1.17 to 2.0 M⊙ and can pin down the radii of more than a dozen to the 9.9−11.2 km range. The combination of the heaviest known neutron star mass with the existing radius measurements already places significant constraints on t ...
Mass Estimate of Black Hole Candidates GRS 1758
... Santa Cruz Institute for Particle Physics Seminar May 23, 2006 ...
... Santa Cruz Institute for Particle Physics Seminar May 23, 2006 ...
Molecular Cloud Turbulence and Star Formation. Ballesteros
... exponentially on the value of Qsg (Li et al., 2005a). In more strongly gravitationally unstable regions towards the centers of galaxies, collapse occurs more generally, with molecular gas dominating over atomic gas, as observed by Wong and Blitz (2002). The multi-kiloparsec scale of spiral arms driv ...
... exponentially on the value of Qsg (Li et al., 2005a). In more strongly gravitationally unstable regions towards the centers of galaxies, collapse occurs more generally, with molecular gas dominating over atomic gas, as observed by Wong and Blitz (2002). The multi-kiloparsec scale of spiral arms driv ...
Zhu Qualifier Solutions - University of Toronto Astronomy
... 4.9.2. Why are there tectonic plates on Earth, but not other planets? ...
... 4.9.2. Why are there tectonic plates on Earth, but not other planets? ...
3011800000631
... higher multipoles, while disks like the one observed in 4U 0142+61 provide the spindown torques on the neutron star, in interaction with its dipole magnetic field. The possibility of such a hybrid situation, with higher multipole fields present on the neutron star surface, bears on several issues. T ...
... higher multipoles, while disks like the one observed in 4U 0142+61 provide the spindown torques on the neutron star, in interaction with its dipole magnetic field. The possibility of such a hybrid situation, with higher multipole fields present on the neutron star surface, bears on several issues. T ...
Multimessenger Astronomy: Modeling Gravitational and Electromagnetic Radiations from a Stellar Binary System
... is the ratio of the change in size of the object to the unaffected size. If we can understand how to detect gravitational waves, we can learn much more information about our galaxy. Just like there is a spectrum of electromagnetic waves, there exists a spectrum of different frequencies of gravitatio ...
... is the ratio of the change in size of the object to the unaffected size. If we can understand how to detect gravitational waves, we can learn much more information about our galaxy. Just like there is a spectrum of electromagnetic waves, there exists a spectrum of different frequencies of gravitatio ...
stellar rotation in m35: mass–period relations, spin
... Free of the ambiguities of v sin(i), Barnes identified, in each coeval stellar population, separate groups of fast and intermediate/ slowly rotating stars with different dependences on color (mass). He specifically proposed that coeval stars fall along two “rotational sequences” in the color versus ...
... Free of the ambiguities of v sin(i), Barnes identified, in each coeval stellar population, separate groups of fast and intermediate/ slowly rotating stars with different dependences on color (mass). He specifically proposed that coeval stars fall along two “rotational sequences” in the color versus ...
Star formation in a galactic outflow
... to the morphological evolution of galaxies12, to the evolution in size and velocity dispersion of the spheroidal component of galaxies11,13, and would contribute to the population of highvelocity stars, which could even escape the galaxy13. Such star formation could provide in-situ chemical enrichme ...
... to the morphological evolution of galaxies12, to the evolution in size and velocity dispersion of the spheroidal component of galaxies11,13, and would contribute to the population of highvelocity stars, which could even escape the galaxy13. Such star formation could provide in-situ chemical enrichme ...
The chemical composition of two supergiants in the dwarf
... globular cluster space velocities are not known. The distance to WLM puts the tip of the red giant branch at V ∼ 22, which is out of reach for detailed chemical abundance analyses of its RGB population. However, there are bright blue supergiants in WLM’s central star forming region with V ∼ 18. Thes ...
... globular cluster space velocities are not known. The distance to WLM puts the tip of the red giant branch at V ∼ 22, which is out of reach for detailed chemical abundance analyses of its RGB population. However, there are bright blue supergiants in WLM’s central star forming region with V ∼ 18. Thes ...
molecular cloud evolution. ii. from cloud formation to the
... We study the formation of giant dense cloud complexes and of stars within them using SPH numerical simulations of the collision of gas streams (‘‘inflows’’) in the WNM at moderately supersonic velocities. The collisions cause compression, cooling, and turbulence generation in the gas, forming a clou ...
... We study the formation of giant dense cloud complexes and of stars within them using SPH numerical simulations of the collision of gas streams (‘‘inflows’’) in the WNM at moderately supersonic velocities. The collisions cause compression, cooling, and turbulence generation in the gas, forming a clou ...
Ages of Young Stars
... resolution (R ≥ 3000) and signal-to-noise ratio to distinguish Li-depletion in very faint, cool stars is challenging. Table 1 lists the apparent Cousins I magnitude of the LDB in the clusters where this has been possible. A photometric survey for candidates is required and subsequent spectroscopy mu ...
... resolution (R ≥ 3000) and signal-to-noise ratio to distinguish Li-depletion in very faint, cool stars is challenging. Table 1 lists the apparent Cousins I magnitude of the LDB in the clusters where this has been possible. A photometric survey for candidates is required and subsequent spectroscopy mu ...
Evolutionary and pulsational properties of white dwarf stars
... of quantum mechanics. In fact, the existence of white dwarfs provided one of the first tests of the quantum theory of matter and a demonstration of the Pauli exclusion principle for electrons. The realization that completely degenerate electrons were the source of internal pressure in the interior o ...
... of quantum mechanics. In fact, the existence of white dwarfs provided one of the first tests of the quantum theory of matter and a demonstration of the Pauli exclusion principle for electrons. The realization that completely degenerate electrons were the source of internal pressure in the interior o ...
Ages of young stars
... resolution (R ≥ 3000) and signal-to-noise ratio to distinguish Li-depletion in very faint, cool stars is challenging. Table 1 lists the apparent Cousins I magnitude of the LDB in the clusters where this has been possible. A photometric survey for candidates is required and subsequent spectroscopy mu ...
... resolution (R ≥ 3000) and signal-to-noise ratio to distinguish Li-depletion in very faint, cool stars is challenging. Table 1 lists the apparent Cousins I magnitude of the LDB in the clusters where this has been possible. A photometric survey for candidates is required and subsequent spectroscopy mu ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.